WorldWideScience

Sample records for assisted reactive pulsed

  1. Reactive pulsed laser deposition with gas jet

    International Nuclear Information System (INIS)

    Rakowski, R.; Bartnik, A.; Fiedorowicz, H.; Jarocki, R.; Kostecki, J.; Szczurek, M.

    2001-01-01

    Different metal (Sn, Al, steel, Cu, W) thin films were synthesized by reactive pulsed laser deposition on steel, copper and glass wafers. In our work pulsed Nd:glass (10 J, 800μs) laser system was used. Jet of gas was created by electromagnetic valve perpendicularly to the laser beam. Nitrogen, oxygen and argon were used. We used several to tens laser shots to obtain visible with the naked eye layers. Thin layers were observed under an optical microscope. (author)

  2. Interaction of UV laser pulses with reactive dusty plasmas

    NARCIS (Netherlands)

    van de Wetering, F.M.J.H.; Beckers, J.; Nijdam, S.; Oosterbeek, W.; Kovacevic, E.; Berndt, J.

    2016-01-01

    This contribution deals with the effects of UV photons on the synthesis and transport of nanoparticles in reactive complex plasmas (capacitively coupled RF discharge). First measurements showed that the irradiation of a reactive acetylene-argon plasma with high-energy, ns UV laser pulses (355 nm, 75

  3. Interaction of nanosecond ultraviolet laser pulses with reactive dusty plasma

    International Nuclear Information System (INIS)

    Wetering, F. M. J. H. van de; Oosterbeek, W.; Beckers, J.; Nijdam, S.; Gibert, T.; Mikikian, M.; Rabat, H.; Kovačević, E.; Berndt, J.

    2016-01-01

    Even though UV laser pulses that irradiate a gas discharge are small compared to the plasma volume (≲3%) and plasma-on time (≲6 × 10 −6 %), they are found to dramatically change the discharge characteristics on a global scale. The reactive argon–acetylene plasma allows the growth of nanoparticles with diameters up to 1 μm, which are formed inside the discharge volume due to spontaneous polymerization reactions. It is found that the laser pulses predominantly accelerate and enhance the coagulation phase and are able to suppress the formation of a dust void.

  4. Optimisation of applied field pulses for microwave assisted magnetic recording

    Directory of Open Access Journals (Sweden)

    Simon John Greaves

    2017-05-01

    Full Text Available Grains in a recording medium experience field pulses from a write head during recording. In general, a short head field rise time and a square pulse shape have been viewed as optimal. This work investigates the optimum field pulse shape for microwave assisted magnetic recording on single layer and ECC media. A square pulse was found to give the best recording performance on single layer media, but an initially negative field pulse increasing at a constant rate was more suitable for ECC media.

  5. Pulsed neutron method for diffusion, slowing down, and reactivity measurements

    International Nuclear Information System (INIS)

    Sjoestrand, N.G.

    1985-01-01

    An outline is given on the principles of the pulsed neutron method for the determination of thermal neutron diffusion parameters, for slowing-down time measurements, and for reactivity determinations. The historical development is sketched from the breakthrough in the middle of the nineteen fifties and the usefulness and limitations of the method are discussed. The importance for the present understanding of neutron slowing-down, thermalization and diffusion are point out. Examples are given of its recent use for e.g. absorption cross section measurements and for the study of the properties of heterogeneous systems

  6. Social support and loneliness in college students: effects on pulse pressure reactivity to acute stress.

    Science.gov (United States)

    O'Donovan, Aoife; Hughes, Brian

    2007-01-01

    Socially supportive relationships at university may buffer against psychological stress in students, particularly in those experiencing loneliness. To examine the relation of social support at university and loneliness with pulse pressure (PP) reactivity to acute psychological stress in a sample of first-year undergraduate students. Sixty-five female, adolescent, first-year university students. Pulse pressure (PP) was calculated as the arithmetic difference between systolic blood pressure and diastolic blood pressure, which were measured during a resting baseline and during a stressful reading task. The difference between baseline and reading task PP represents PP reactivity. The Social Support at University Scale (SSUS) was used to assess social support availability in university, and the Revised UCLA Loneliness Scale was used to assess loneliness. Hierarchical linear regression was used to examine main and interactive effects of SSUS and loneliness on PP change scores, and simple slopes were computed to assist in the interpretation of interaction effects. Social support at university was associated with lower PP reactivity in students reporting medium (t = -2.03, p = .04) or high levels of loneliness (t = -2.93, p = .004), but not in those reporting low levels of loneliness (t = -0.20, p = .83). Psychosocial interventions designed to increase social support available at university, and targeted at students experiencing loneliness may buffer against the harmful effects of acute stressors in lonely first-year students.

  7. Water spray assisted ultrashort laser pulse ablation

    International Nuclear Information System (INIS)

    Silvennoinen, M.; Kaakkunen, J.J.J.; Paivasaari, K.; Vahimaa, P.

    2013-01-01

    Highlights: ► We show the novel method to use multibeam processing with ultrashort pulses efficiently. ► Sprayed thin water layer on ablation zone enhances ablation rate and quality. ► In some cases this method also enables ablation of the deeper and straighter holes compared to ones made without the water layer. ► Method also makes possible to directly write features without the self-organizing structures. - Abstract: We have studied femtosecond ablation under sprayed thin water film and its influence and benefits compared with ablation in the air atmosphere. These have been studied in case of the hole and the groove ablation using IR femtosecond laser. Water enhances the ablation rate and in some situations it makes possible to ablate the holes with a higher aspect ratio. While ablating the grooves, the water spray allows using the high fluences without the generation of the self-organized structures.

  8. Tracing the plasma interactions for pulsed reactive crossed-beam laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jikun; Stender, Dieter; Pichler, Markus; Pergolesi, Daniele; Schneider, Christof W.; Wokaun, Alexander; Lippert, Thomas, E-mail: thomas.lippert@psi.ch [General Energy Research Department, Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland); Döbeli, Max [Ion Beam Physics, ETH Zurich, CH-8093 Zurich (Switzerland)

    2015-10-28

    Pulsed reactive crossed-beam laser ablation is an effective technique to govern the chemical activity of plasma species and background molecules during pulsed laser deposition. Instead of using a constant background pressure, a gas pulse with a reactive gas, synchronized with the laser beam, is injected into vacuum or a low background pressure near the ablated area of the target. It intercepts the initially generated plasma plume, thereby enhancing the physicochemical interactions between the gaseous environment and the plasma species. For this study, kinetic energy resolved mass-spectrometry and time-resolved plasma imaging were used to study the physicochemical processes occurring during the reactive crossed beam laser ablation of a partially {sup 18}O substituted La{sub 0.6}Sr{sub 0.4}MnO{sub 3} target using oxygen as gas pulse. The characteristics of the ablated plasma are compared with those observed during pulsed laser deposition in different oxygen background pressures.

  9. Tracing the plasma interactions for pulsed reactive crossed-beam laser ablation

    Science.gov (United States)

    Chen, Jikun; Stender, Dieter; Pichler, Markus; Döbeli, Max; Pergolesi, Daniele; Schneider, Christof W.; Wokaun, Alexander; Lippert, Thomas

    2015-10-01

    Pulsed reactive crossed-beam laser ablation is an effective technique to govern the chemical activity of plasma species and background molecules during pulsed laser deposition. Instead of using a constant background pressure, a gas pulse with a reactive gas, synchronized with the laser beam, is injected into vacuum or a low background pressure near the ablated area of the target. It intercepts the initially generated plasma plume, thereby enhancing the physicochemical interactions between the gaseous environment and the plasma species. For this study, kinetic energy resolved mass-spectrometry and time-resolved plasma imaging were used to study the physicochemical processes occurring during the reactive crossed beam laser ablation of a partially 18O substituted La0.6Sr0.4MnO3 target using oxygen as gas pulse. The characteristics of the ablated plasma are compared with those observed during pulsed laser deposition in different oxygen background pressures.

  10. Lipase biofilm deposited by Matrix Assisted Pulsed Laser Evaporation technique

    International Nuclear Information System (INIS)

    Aronne, Antonio; Bloisi, Francesco; Calabria, Raffaela; Califano, Valeria; Depero, Laura E.; Fanelli, Esther; Federici, Stefania; Massoli, Patrizio; Vicari, Luciano R.M.

    2015-01-01

    Highlights: • A lipase film was deposited with Matrix Assisted Pulsed Laser Evaporation technique. • FTIR spectra show that laser irradiation do not damage lipase molecule. • Laser fluence controls the characteristics of complex structure generated by MAPLE. - Abstract: Lipase is an enzyme that finds application in biodiesel production and for detection of esters and triglycerides in biosensors. Matrix Assisted Pulsed Laser Evaporation (MAPLE), a technique derived from Pulsed Laser Deposition (PLD) for deposition of undamaged biomolecules or polymers, is characterized by the use of a frozen target obtained from a solution/suspension of the guest material (to be deposited) in a volatile matrix (solvent). The presence of the solvent avoids or at least reduces the potential damage of guest molecules by laser radiation but only the guest material reaches the substrate in an essentially solvent-free deposition. MAPLE can be used for enzymes immobilization, essential for industrial application, allowing the development of continuous processes, an easier separation of products, the reuse of the catalyst and, in some cases, enhancing enzyme properties (pH, temperature stability, etc.) and catalytic activity in non-aqueous media. Here we show that MAPLE technique can be used to deposit undamaged lipase and that the complex structure (due to droplets generated during extraction from target) of the deposited material can be controlled by changing the laser beam fluence

  11. Lipase biofilm deposited by Matrix Assisted Pulsed Laser Evaporation technique

    Energy Technology Data Exchange (ETDEWEB)

    Aronne, Antonio [Department of Chemical Engineering, Materials and Industrial Production, University of Naples “Federico II”, Napoli (Italy); Bloisi, Francesco, E-mail: bloisi@na.infn.it [SPIN – CNR, Naples (Italy); Department of Physics, University of Naples “Federico II”, Napoli (Italy); Calabria, Raffaela; Califano, Valeria [Istituto Motori – CNR, Naples (Italy); Depero, Laura E. [Department of Mechanical and Industrial Engineering, University of Brescia, Brescia (Italy); Fanelli, Esther [Department of Chemical Engineering, Materials and Industrial Production, University of Naples “Federico II”, Napoli (Italy); Federici, Stefania [Department of Mechanical and Industrial Engineering, University of Brescia, Brescia (Italy); Massoli, Patrizio [Istituto Motori – CNR, Naples (Italy); Vicari, Luciano R.M. [SPIN – CNR, Naples (Italy); Department of Physics, University of Naples “Federico II”, Napoli (Italy)

    2015-05-01

    Highlights: • A lipase film was deposited with Matrix Assisted Pulsed Laser Evaporation technique. • FTIR spectra show that laser irradiation do not damage lipase molecule. • Laser fluence controls the characteristics of complex structure generated by MAPLE. - Abstract: Lipase is an enzyme that finds application in biodiesel production and for detection of esters and triglycerides in biosensors. Matrix Assisted Pulsed Laser Evaporation (MAPLE), a technique derived from Pulsed Laser Deposition (PLD) for deposition of undamaged biomolecules or polymers, is characterized by the use of a frozen target obtained from a solution/suspension of the guest material (to be deposited) in a volatile matrix (solvent). The presence of the solvent avoids or at least reduces the potential damage of guest molecules by laser radiation but only the guest material reaches the substrate in an essentially solvent-free deposition. MAPLE can be used for enzymes immobilization, essential for industrial application, allowing the development of continuous processes, an easier separation of products, the reuse of the catalyst and, in some cases, enhancing enzyme properties (pH, temperature stability, etc.) and catalytic activity in non-aqueous media. Here we show that MAPLE technique can be used to deposit undamaged lipase and that the complex structure (due to droplets generated during extraction from target) of the deposited material can be controlled by changing the laser beam fluence.

  12. Comparative study on Pulsed Laser Deposition and Matrix Assisted Pulsed Laser Evaporation of urease thin films

    International Nuclear Information System (INIS)

    Smausz, Tomi; Megyeri, Gabor; Kekesi, Renata; Vass, Csaba; Gyoergy, Eniko; Sima, Felix; Mihailescu, Ion N.; Hopp, Bela

    2009-01-01

    Urease thin films were produced by Matrix Assisted Pulsed Laser Evaporation (MAPLE) and Pulsed Laser Deposition from two types of targets: frozen water solutions of urease with different concentrations (1-10% m/v) and pure urease pellets. The fluence of the ablating KrF excimer laser was varied between 300 and 2200 mJ/cm 2 . Fourier transform infrared spectra of the deposited films showed no difference as compared to the original urease. Morphologic studies proved that the films consist of a smooth 'base' layer with embedded micrometer-sized droplets. Absorption-coefficient measurements contradicted the traditional 'absorptive matrix' model for MAPLE deposition. The laser energy was absorbed by urease clusters leading to a local heating-up and evaporation of the frozen matrix from the uppermost layer accompanied by the release of dissolved urease molecules. Significant enzymatic activity of urease was preserved only during matrix assisted transfer.

  13. Oxygen-assisted multipass cutting of carbon fiber reinforced plastics with ultra-short laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Kononenko, T. V.; Komlenok, M. S.; Konov, V. I. [Natural Sciences Center, General Physics Institute, Vavilov str. 38, 119991 Moscow (Russian Federation); National Research Nuclear University, “MEPhI,” Kashirskoye shosse 31, 115409 Moscow (Russian Federation); Freitag, C. [Universität Stuttgart, Institut für Strahlwerkzeuge (IFSW), Pfaffenwaldring 43, 70569 Stuttgart (Germany); GSaME Graduate School of Excellence Advanced Manufacturing Engineering, Nobelstrasse 12, 70569 Stuttgart (Germany); Onuseit, V.; Weber, R.; Graf, T. [Universität Stuttgart, Institut für Strahlwerkzeuge (IFSW), Pfaffenwaldring 43, 70569 Stuttgart (Germany)

    2014-03-14

    Deep multipass cutting of bidirectional and unidirectional carbon fiber reinforced plastics (CFRP) with picosecond laser pulses was investigated in different static atmospheres as well as with the assistance of an oxygen or nitrogen gas flow. The ablation rate was determined as a function of the kerf depth and the resulting heat affected zone was measured. An assisting oxygen gas flow is found to significantly increase the cutting productivity, but only in deep kerfs where the diminished evaporative ablation due to the reduced laser fluence reaching the bottom of the kerf does not dominate the contribution of reactive etching anymore. Oxygen-supported cutting was shown to also solve the problem that occurs when cutting the CFRP parallel to the fiber orientation where a strong deformation and widening of the kerf, which temporarily slows down the process speed, is revealed to be typical for processing in standard air atmospheres.

  14. Oxygen-assisted multipass cutting of carbon fiber reinforced plastics with ultra-short laser pulses

    International Nuclear Information System (INIS)

    Kononenko, T. V.; Komlenok, M. S.; Konov, V. I.; Freitag, C.; Onuseit, V.; Weber, R.; Graf, T.

    2014-01-01

    Deep multipass cutting of bidirectional and unidirectional carbon fiber reinforced plastics (CFRP) with picosecond laser pulses was investigated in different static atmospheres as well as with the assistance of an oxygen or nitrogen gas flow. The ablation rate was determined as a function of the kerf depth and the resulting heat affected zone was measured. An assisting oxygen gas flow is found to significantly increase the cutting productivity, but only in deep kerfs where the diminished evaporative ablation due to the reduced laser fluence reaching the bottom of the kerf does not dominate the contribution of reactive etching anymore. Oxygen-supported cutting was shown to also solve the problem that occurs when cutting the CFRP parallel to the fiber orientation where a strong deformation and widening of the kerf, which temporarily slows down the process speed, is revealed to be typical for processing in standard air atmospheres

  15. Reactive ion assisted deposition of aluminum oxynitride thin films

    International Nuclear Information System (INIS)

    Hwangbo, C.K.; Lingg, L.J.; Lehan, J.P.; Macleod, H.A.; Suits, F.

    1989-01-01

    Optical properties, stoichiometry, chemical bonding states, and crystal structure of aluminum oxynitride (AlO/sub x/N/sub y/) thin films prepared by reactive ion assisted deposition were investigated. The results show that by controlling the amount of reactive gases the refractive index of aluminum oxynitride films at 550 nm is able to be varied from 1.65 to 1.83 with a very small extinction coefficient. Variations of optical constants and chemical bonding states of aluminum oxynitride films are related to the stoichiometry. From an x-ray photoelectron spectroscopy analysis it is observed that our aluminum oxynitride film is not simply a mixture of aluminum oxide and aluminum nitride but a continuously variable compound. The aluminum oxynitride films are amorphous from an x-ray diffraction analysis. A rugate filter using a step index profile of aluminum oxynitride films was fabricated by nitrogen ion beam bombardment of a growing Al film with backfill oxygen pressure as the sole variation. This filter shows a high resistivity to atmospheric moisture adsorption, suggesting that the packing density of aluminum oxynitride films is close to unity and the energetic ion bombardment densifies the film as well as forming the compound

  16. Pulsed EPR studies of small reactive radicals produced by ionizing radiation

    International Nuclear Information System (INIS)

    Lawler, R.G.

    1985-01-01

    For several years we have participated in a collaborative research effort to apply the pulsed EPR-pulse radiolysis technique to several problems associated with the dynamics of small reactive radicals formed during radiolysis of aqueous solutions using 3 MeV electrons from a Van de Graaff accelerator. We will discuss experimental techniques and applications arising from this work, with particular emphasis on problems requiring high initial radical concentrations and EPR time resolution of one microsecond or better. 2 figs., 2 tabs

  17. Deposition of zinc oxide thin films by reactive pulsed laser ablation

    Czech Academy of Sciences Publication Activity Database

    Bílková, Petra; Zemek, Josef; Mitu, B.; Marotta, V.; Orlando, S.

    2006-01-01

    Roč. 252, - (2006), s. 4604-4609 ISSN 0169-4332 Grant - others:NATO-CNR Outreach Fellowships Programm 2001(XE) 219.34 Institutional research plan: CEZ:AV0Z10100521 Keywords : reactive pulsed laser deposition * zinc oxide * thin films Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.436, year: 2006

  18. Guanosine radical reactivity explored by pulse radiolysis coupled with transient electrochemistry.

    Science.gov (United States)

    Latus, A; Alam, M S; Mostafavi, M; Marignier, J-L; Maisonhaute, E

    2015-06-04

    We follow the reactivity of a guanosine radical created by a radiolytic electron pulse both by spectroscopic and electrochemical methods. This original approach allows us to demonstrate that there is a competition between oxidation and reduction of these intermediates, an important result to further analyse the degradation or repair pathways of DNA bases.

  19. Analysis of rod drop and pulsed source measurements of reactivity in the Winfrith SGHWR

    International Nuclear Information System (INIS)

    Brittain, I.

    1970-05-01

    Reactivity measurements by the rod-drop and pulsed source methods in the Winfrith SGHWR are seriously affected by spatial harmonics. A method of calculation is described which enables the spatial harmonics to be calculated in non-uniform cores in two or three dimensions, and thus allows a much more rigorous analysis of the experimental results than the usual point model. The method is used to analyse all the rod-drop measurements made during commissioning of the Winfrith SGHWR, and to comment on the results of pulsed source measurements. The reactivity worths of banks of ten and twelve shut-down tubes deduced from rod-drop and pulsed source experiments are in satisfactory agreement with each other and also with AIMAZ calculated values. The ability to calculate higher spatial harmonics in nonuniform cores is thought to be new, and may have a wider application to reactor kinetics through the method of Modal Analysis. (author)

  20. A novel non-sequential hydrogen-pulsed deep reactive ion etching of silicon

    International Nuclear Information System (INIS)

    Gharooni, M; Mohajerzadeh, A; Sandoughsaz, A; Khanof, S; Mohajerzadeh, S; Asl-Soleimani, E

    2013-01-01

    A non-sequential pulsed-mode deep reactive ion etching of silicon is reported that employs continuous etching and passivation based on SF 6 and H 2 gases. The passivation layer, as an important step for deep vertical etching of silicon, is feasible by hydrogen pulses in proper time-slots. By adjusting the etching parameters such as plasma power, H 2 and SF 6 flows and hydrogen pulse timing, the process can be controlled for minimum underetch and high etch-rate at the same time. High-aspect-ratio features can be realized with low-density plasma power and by controlling the reaction chemistry. The so-called reactive ion etching lag has been minimized by operating the reactor at higher pressures. X-ray photoelectron spectroscopy and scanning electron microscopy have been used to study the formation of the passivation layer and the passivation mechanism. (paper)

  1. Hydroxyapatite thin films grown by pulsed laser deposition and matrix assisted pulsed laser evaporation: Comparative study

    Science.gov (United States)

    Popescu-Pelin, G.; Sima, F.; Sima, L. E.; Mihailescu, C. N.; Luculescu, C.; Iordache, I.; Socol, M.; Socol, G.; Mihailescu, I. N.

    2017-10-01

    Pulsed Laser Deposition (PLD) and Matrix Assisted Pulsed Laser Evaporation (MAPLE) techniques were applied for growing hydroxyapatite (HA) thin films on titanium substrates. All experiments were conducted in a reaction chamber using a KrF* excimer laser source (λ = 248 nm, τFWHM ≈ 25 ns). Half of the samples were post-deposition thermally treated at 500 °C in a flux of water vapours in order to restore crystallinity and improve adherence. Coating surface morphologies and topographies specific to the deposition method were evidenced by scanning electron, atomic force microscopy investigations and profilometry. They were shown to depend on deposition technique and also on the post-deposition treatment. Crystalline structure of the coatings evaluated by X-ray diffraction was improved after thermal treatment. Biocompatibility of coatings, cellular adhesion, proliferation and differentiation tests were conducted using human mesenchymal stem cells (MSCs). Results showed that annealed MAPLE deposited HA coatings were supporting MSCs proliferation, while annealed PLD obtained films were stimulating osteogenic differentiation.

  2. Method of analysis to determine subcritical reactivity from the pulsed neutron experiment

    International Nuclear Information System (INIS)

    Parks, P.B.

    1975-06-01

    The published methods for the deduction of reactivity from pulsed neutron experiments on subcritical reactors are reviewed. Each method is categorized as inherently yielding a result that is either spatially independent or spatially dependent. The spatially independent results are formally identical with the static reactivity; the result does not depend, in principle, on the location of either the pulsed neutron source or the neutron detector during data collection. The spatially dependent results only approximate the static reactivity; the results are affected, in varying degrees, by the locations of the source and detector. Among the techniques yielding spatially independent results are the Space-Time method of Parks and Stewart and the Inhour method of Preskitt et al. Spatially dependent results are obtained with the Sjoestrand, Gozani, and Garelis-Russell methods which are examined with and without the kinetic distortion corrections given by Becker and Quisenberry. Intercomparisons of all methods are made with reference to pulsed neutron experiments on both unreflected and reflected reactors. Recommendations are made concerning the best choice of method under the various experimental conditions that are likely to be encountered. 14 references. (U.S.)

  3. Pulsed Electromagnetic Field Assisted in vitro Electroporation: A Pilot Study

    Science.gov (United States)

    Novickij, Vitalij; Grainys, Audrius; Lastauskienė, Eglė; Kananavičiūtė, Rūta; Pamedytytė, Dovilė; Kalėdienė, Lilija; Novickij, Jurij; Miklavčič, Damijan

    2016-09-01

    Electroporation is a phenomenon occurring due to exposure of cells to Pulsed Electric Fields (PEF) which leads to increase of membrane permeability. Electroporation is used in medicine, biotechnology, and food processing. Recently, as an alternative to electroporation by PEF, Pulsed ElectroMagnetic Fields (PEMF) application causing similar biological effects was suggested. Since induced electric field in PEMF however is 2-3 magnitudes lower than in PEF electroporation, the membrane permeabilization mechanism remains hypothetical. We have designed pilot experiments where Saccharomyces cerevisiae and Candida lusitaniae cells were subjected to single 100-250 μs electrical pulse of 800 V with and without concomitant delivery of magnetic pulse (3, 6 and 9 T). As expected, after the PEF pulses only the number of Propidium Iodide (PI) fluorescent cells has increased, indicative of membrane permeabilization. We further show that single sub-millisecond magnetic field pulse did not cause detectable poration of yeast. Concomitant exposure of cells to pulsed electric (PEF) and magnetic field (PMF) however resulted in the increased number PI fluorescent cells and reduced viability. Our results show increased membrane permeability by PEF when combined with magnetic field pulse, which can explain electroporation at considerably lower electric field strengths induced by PEMF compared to classical electroporation.

  4. The dynamics of Al/Pt reactive multilayer ignition via pulsed-laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, Ryan D.; Reeves, Robert V.; Yarrington, Cole D.; Adams, David P. [Sandia National Laboratories, Albuquerque, New Mexico 87123 (United States)

    2015-12-07

    Reactive multilayers consisting of alternating layers of Al and Pt were irradiated by single laser pulses ranging from 100 μs to 100 ms in duration, resulting in the initiation of rapid, self-propagating reactions. The threshold intensities for ignition vary with the focused laser beam diameter, bilayer thickness, and pulse length and are affected by solid state reactions and conduction of heat away from the irradiated regions. High-speed photography was used to observe ignition dynamics during irradiation and elucidate the effects of heat transfer into a multilayer foil. For an increasing laser pulse length, the ignition process transitioned from a more uniform to a less uniform temperature profile within the laser-heated zone. A more uniform temperature profile is attributed to rapid heating rates and heat localization for shorter laser pulses, and a less uniform temperature profile is due to slower heating of reactants and conduction during irradiation by longer laser pulses. Finite element simulations of laser heating using measured threshold intensities indicate that micron-scale ignition of Al/Pt occurs at low temperatures, below the melting point of both reactants.

  5. InTaO4-based nanostructures synthesized by reactive pulsed laser ablation

    International Nuclear Information System (INIS)

    Yoshida, Takehito; Toyoyama, Hirokazu; Umezu, Ikurou; Sugimura, Akira

    2008-01-01

    Nanostructured Ni-doped indium-tantalum-oxides (InTaO 4 ) were synthesized by a reactive pulsed laser ablation process, aiming at the final goal of direct splitting of water under visible sunbeam irradiation. The third harmonics beam of a Nd:YAG laser was focused onto a sintered In 0.9 Ni 0.1 TaO 4-δ target in pure oxygen background gases (0.05-1.00 Torr). Increasing the oxygen gas pressure, via thin films having nanometer-sized strong morphologies, single-crystalline nanoparticles were synthesized in the reactive vapor phases. The nanostructured deposited materials have the monoclinic layered wolframite-type structure of bulk InTaO 4 , without oxygen deficiency. (orig.)

  6. Control Rod Reactivity Measurements in the Aagesta Reactor with the Pulsed Neutron Method

    Energy Technology Data Exchange (ETDEWEB)

    Bjoereus, K

    1969-07-01

    An extensive series of control rod measurements was made in the Aagesta reactor during the low power experimental period following the first criticality. This report describes the part of these investigations made with the pulsed neutron method, comprising nearly 300 measurements. The main objective was the determination of control rod reactivity worths for different rods and groups of rods, but some supplementary measurements were also made, e.g. a determination of the prompt neutron decay constant for the delayed critical condition and four different cores. The cores consisted of 20, 32, 68, and 140 fuel elements respectively, and measurements were made at room temperature and with the moderator level close to critical for each core, and for the 140-element core also with full moderator height and at the temperatures 140 deg C and 215 deg C. Both fully and partly inserted control rod groups were investigated. The measurements at critical water level give directly the control rod reactivity worths, whereas those with full water height give the shut-down reactivity. A comparison was made between measured reactivity worths for a number of rod groups and those calculated with the HETERO code. The prompt neutron decay constant at delayed criticality {alpha}{sub 0}={beta}/l, for the full core at 215 deg C was found to be 9.60 {+-} 0.30/sec, corresponding to l = 0.76 {+-} 0.02 msec. The shut-down reactivity with 16 coarse control rods in pos. A-D 22, 40-04, 44, 26 is -5% at 25 deg C and -13% at 215 deg C. The relative error is usually around 8% in the reactivity worths, originating mainly from the higher harmonics content in the measured curves.

  7. Biomimetic nanocrystalline apatite coatings synthesized by Matrix Assisted Pulsed Laser Evaporation for medical applications

    Energy Technology Data Exchange (ETDEWEB)

    Visan, A. [National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, RO-77125, MG-36, Magurele-Ilfov (Romania); Grossin, D. [CIRIMAT – Carnot Institute, University of Toulouse, ENSIACET, 4 Allée Emile Monso, 31030 Toulouse Cedex 4 (France); Stefan, N.; Duta, L.; Miroiu, F.M. [National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, RO-77125, MG-36, Magurele-Ilfov (Romania); Stan, G.E. [National Institute of Materials Physics, RO-077125, Magurele-Ilfov (Romania); Sopronyi, M.; Luculescu, C. [National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, RO-77125, MG-36, Magurele-Ilfov (Romania); Freche, M.; Marsan, O.; Charvilat, C. [CIRIMAT – Carnot Institute, University of Toulouse, ENSIACET, 4 Allée Emile Monso, 31030 Toulouse Cedex 4 (France); Ciuca, S. [Politehnica University of Bucharest, Faculty of Materials Science and Engineering, Bucharest (Romania); Mihailescu, I.N., E-mail: ion.mihailescu@inflpr.ro [National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, RO-77125, MG-36, Magurele-Ilfov (Romania)

    2014-02-15

    Highlights: • We report the deposition by MAPLE of biomimetic apatite coatings on Ti substrates. • This is the first report of MAPLE deposition of hydrated biomimetic apatite films. • Biomimetic apatite powder was synthesized by double decomposition process. • Non-apatitic environments, of high surface reactivity, are preserved post-deposition. • We got the MAPLE complete transfer as thin film of a hydrated, delicate material. -- Abstract: We report the deposition by Matrix Assisted Pulsed Laser Evaporation (MAPLE) technique of biomimetic nanocrystalline apatite coatings on titanium substrates, with potential application in tissue engineering. The targets were prepared from metastable, nanometric, poorly crystalline apatite powders, analogous to mineral bone, synthesized through a biomimetic approach by double decomposition process. For the deposition of thin films, a KrF* excimer laser source was used (λ = 248 nm, τ{sub FWHM} ≤ 25 ns). The analyses revealed the existence, in synthesized powders, of labile non-apatitic mineral ions, associated with the formation of a hydrated layer at the surface of the nanocrystals. The thin film analyses showed that the structural and chemical nature of the nanocrystalline apatite was prevalently preserved. The perpetuation of the non-apatitic environments was also observed. The study indicated that MAPLE is a suitable technique for the congruent transfer of a delicate material, such as the biomimetic hydrated nanohydroxyapatite.

  8. Biomimetic nanocrystalline apatite coatings synthesized by Matrix Assisted Pulsed Laser Evaporation for medical applications

    International Nuclear Information System (INIS)

    Visan, A.; Grossin, D.; Stefan, N.; Duta, L.; Miroiu, F.M.; Stan, G.E.; Sopronyi, M.; Luculescu, C.; Freche, M.; Marsan, O.; Charvilat, C.; Ciuca, S.; Mihailescu, I.N.

    2014-01-01

    Highlights: • We report the deposition by MAPLE of biomimetic apatite coatings on Ti substrates. • This is the first report of MAPLE deposition of hydrated biomimetic apatite films. • Biomimetic apatite powder was synthesized by double decomposition process. • Non-apatitic environments, of high surface reactivity, are preserved post-deposition. • We got the MAPLE complete transfer as thin film of a hydrated, delicate material. -- Abstract: We report the deposition by Matrix Assisted Pulsed Laser Evaporation (MAPLE) technique of biomimetic nanocrystalline apatite coatings on titanium substrates, with potential application in tissue engineering. The targets were prepared from metastable, nanometric, poorly crystalline apatite powders, analogous to mineral bone, synthesized through a biomimetic approach by double decomposition process. For the deposition of thin films, a KrF* excimer laser source was used (λ = 248 nm, τ FWHM ≤ 25 ns). The analyses revealed the existence, in synthesized powders, of labile non-apatitic mineral ions, associated with the formation of a hydrated layer at the surface of the nanocrystals. The thin film analyses showed that the structural and chemical nature of the nanocrystalline apatite was prevalently preserved. The perpetuation of the non-apatitic environments was also observed. The study indicated that MAPLE is a suitable technique for the congruent transfer of a delicate material, such as the biomimetic hydrated nanohydroxyapatite

  9. Growth and characterization of polycrystalline Ge1-xCx by reactive pulsed laser deposition

    International Nuclear Information System (INIS)

    Hernandez, M.P.; Farias, M.H.; Castillon, F.F.; Diaz, Jesus A.; Avalos, M.; Ulloa, L.; Gallegos, J.A.; Yee-Madeiros, H.

    2011-01-01

    Polycrystalline thin films of Ge-C were grown on Si (1 1 1) substrates by means of reactive pulsed laser deposition with methane pressure of 100 mTorr. Effect substrate temperature, T s , on C incorporation to substitutional sites (x) in Ge 1-x C x was investigated systematically by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyzes. The substrate temperatures were ranging from 250 to 400 deg. C. The substitutional C composition x in the films by XRD were estimated using the Vegard's linear law. The maximum value of x calculated by XRD was 0.032 for T s of 350 deg. C. The position of the C 1s peak at 283.4 eV in the XPS spectrum confirmed the germanium-carbon alloys. XRD measurements indicated that x increased with T s from 250 deg. C to 350 deg. C. At T s = 400 deg. C, the estimation of x was lowered. However, the C content calculated by XPS analyzes increased with T s being more these values than substitutional C composition x. XPS and XRD analyzes demonstrate that the remaining C atoms are incorporated to interstitial sites. The use of the T s plays important roles in the incorporation of substitutional C and in restraining C-cluster formation in the reactive pulsed laser deposition growth of Ge-C/Si.

  10. Sandia Pulsed Reactor Facility (SPRF) calculator-assisted pulse analysis and display system

    International Nuclear Information System (INIS)

    Estes, B.F.; Berry, D.T.

    1980-02-01

    Two solid-metal fast burst type reactors (SPR II and SPR III) are operated at the Sandia Pulsed Reactor Facility. Since startup of the reactors, oscilloscope traces have been used to record (by camera) the pulse (power) shape while log N systems have measured initial reactor period. Virtually no other pulse information is available. A decision was made to build a system that could collect the basic input data available from the reactor - fission chambers, photodiodes, and thermocouples - condition the signals and output the various parameters such as power, energy, temperature, period and lifetime on hard copy that would provide a record for operations personnel as well as the experimenter. Because the reactors operate in short time frames - pulse operation - it is convenient to utilize the classical Nordheim-Fuchs approximation of the diffusion equation to describe reactor behavior. This report describes the work performed to date in developing the calculator system and analytical models for computing the desired parameters

  11. Aluminum oxide films deposited in low pressure conditions by reactive pulsed dc magnetron sputtering

    CERN Document Server

    Seino, T

    2002-01-01

    The reactive pulsed dc sputtering technique is widely used for the deposition of oxide films. The operating pressure for sputtering is commonly above 0.13 Pa. In this study, however, aluminum oxide (alumina) films were deposited at operating pressures from 0.06 to 0.4 Pa using a sputtering system equipped with a scanning magnetron cathode and a pulsed dc power supply. The pulsed dc power was found to be useful not only to reduce arcing, but also to sustain the discharge at low pressure. The electrical breakdown field, intrinsic stress, O/Al ratio, refractive index, and surface roughness were investigated. Both a low intrinsic stress and an O/Al ratio around the stoichiometry were required to get the film having a high breakdown field. A low operating pressure of 0.1 Pa was found to provide the necessary stress and O/Al ratio targets. A 50-nm-thick alumina film having a maximum breakdown field of 7.4 MV/cm was obtained.

  12. Fermentation Assisted by Pulsed Electric Field and Ultrasound: A Review

    Directory of Open Access Journals (Sweden)

    Leandro Galván-D’Alessandro

    2018-01-01

    Full Text Available Various novel techniques are proposed to improve process efficiency, quality, and safety of fermented food products. Ultrasound and pulsed electric field (PEF are versatile technologies that can be employed in conjunction with fermentation processes to enhance process efficiency and production rates by improving mass transfer and cell permeability. The aim of this review is to highlight current and potential applications of ultrasound and PEF techniques in food fermentation processes. Their effects on microbial enzymes, along with mechanisms of action, are also discussed.

  13. Gain assisted coherent control of microwave pulse in a one dimensional array of artificial atoms

    Science.gov (United States)

    Waqas, Mohsin; Ayaz, M. Q.; Waseem, M.; Qamar, Sajid; Qamar, Shahid

    2018-06-01

    We study the coherent propagation of a microwave pulse through a one-dimensional array of artificial atoms. The scheme is based upon gain assisted propagation of the pulse using two-photon Raman transition in a three-level superconducting artificial atoms (SAAs) coupled to a microwave transmission line. Our results show that the group velocity can be significantly reduced by increasing the Rabi frequency of the pump fields which in turn can lead to an efficient storage of the pulse inside a 1D array of SAAs. Further, the intensity of the transmitted pulse increases with the number of artificial atoms owing to the gain associated with the two-photon Raman transition. Our results also show that the window width decreases for both scattering and negligible scattering cases with the increase in the number of SAAs. The fidelity of the system also remains high even after the passage of the pulse through a large number of SAAs.

  14. WOx cluster formation in radio frequency assisted pulsed laser deposition

    International Nuclear Information System (INIS)

    Filipescu, M.; Ossi, P.M.; Dinescu, M.

    2007-01-01

    The influence of oxygen gas pressure and radio-frequency power on the characteristics of the WO x films produced by laser ablation of a W target at room temperature in oxygen reactive atmosphere were investigated. Changing buffer gas pressure in the hundreds of Pa range affects the bond coordination, roughness and morphology of the deposited films, as investigated by micro-Raman spectroscopy, atomic force microscopy and scanning electron microscopy. The combination of radio-frequency discharge and buffer gas pressure on film nanostructure, as reflected by bond coordination, surface morphology and roughness is discussed

  15. Surface Texturing of CVD Diamond Assisted by Ultrashort Laser Pulses

    Directory of Open Access Journals (Sweden)

    Daniele M. Trucchi

    2017-11-01

    Full Text Available Diamond is a wide bandgap semiconductor with excellent physical properties which allow it to operate under extreme conditions. However, the technological use of diamond was mostly conceived for the fabrication of ultraviolet, ionizing radiation and nuclear detectors, of electron emitters, and of power electronic devices. The use of nanosecond pulse excimer lasers enabled the microstructuring of diamond surfaces, and refined techniques such as controlled ablation through graphitization and etching by two-photon surface excitation are being exploited for the nanostructuring of diamond. On the other hand, ultrashort pulse lasers paved the way for a more accurate diamond microstructuring, due to reduced thermal effects, as well as an effective surface nanostructuring, based on the formation of periodic structures at the nanoscale. It resulted in drastic modifications of the optical and electronic properties of diamond, of which “black diamond” films are an example for future high-temperature solar cells as well as for advanced optoelectronic platforms. Although experiments on diamond nanostructuring started almost 20 years ago, real applications are only today under implementation.

  16. Transmission of reactive pulsed laser deposited VO{sub 2} films in the THz domain

    Energy Technology Data Exchange (ETDEWEB)

    Émond, Nicolas; Hendaoui, Ali; Ibrahim, Akram; Al-Naib, Ibraheem; Ozaki, Tsuneyuki; Chaker, Mohamed, E-mail: chaker@emt.inrs.ca

    2016-08-30

    Highlights: • Synthesis of vanadium dioxide (VO{sub 2}) thin films as a function of oxygen pressure (2–25 mTorr) using Reactive Pulsed Laser Deposition (RPLD). • Characterization of RPLD-grown VO{sub 2} thin films in the THz frequency range. • THz switches and/or sensors require VO{sub 2} films deposited at low oxygen pressure (i.e. low transition temperature, large amplitude contrast of THz transmission, narrow hysteresis width). • THz optical memory applications require VO{sub 2} films deposited at high oxygen pressure (broad hysteresis width). - Abstract: This work reports on the characteristics of the insulator-to-metal transition (IMT) of reactive pulsed laser deposited vanadium dioxide (VO{sub 2}) films in the terahertz (THz) frequency range, namely the transition temperature T{sub IMT}, the amplitude contrast of the THz transmission over the IMT ΔA, the transition sharpness ΔT and the hysteresis width ΔH. XRD analysis shows the sole formation of VO{sub 2} monoclinic structure with an enhancement of (011) preferential orientation when varying the O{sub 2} pressure (P{sub O2}) during the deposition process from 2 to 25 mTorr. THz transmission measurements as a function of temperature reveal that VO{sub 2} films obtained at low P{sub O2} exhibit low T{sub IMT}, large ΔA, and narrow ΔH. Increasing P{sub O2} results in VO{sub 2} films with higher T{sub IMT}, smaller ΔA, broader ΔH and asymmetric hysteresis loop. The good control of the VO{sub 2} IMT features in the THz domain could be further exploited for the development of advanced smart devices, such as ultrafast switches, modulators, memories and sensors.

  17. Pulsed reactivity measurements of large 235U--Al castings in H2O

    International Nuclear Information System (INIS)

    Pellarin, D.J.; Jarriel, J.L.

    1977-01-01

    The safe storage and handling of large 235 U-Al castings at the Savannah River Plant are assured by limiting the number of fuel pieces and their spacing such that the k/sub eff/ calculated by KENO-IV with Hansen-Roach cross sections does not exceed some conservative limit with complete, accidental water immersion. For economic reasons, the conservative limit on the calculated k/sub eff/ is generally chosen as high as possible consistent with an accurate knowledge of the margin of error in the k/sub eff/ calculation. The margin of error for arrays of large, hollow cylinders of highly enriched 235 U-Al alloy fuel in H 2 O is presented. The subcritical reactivities were derived from pulsed neutron measurements. The measurements are extended to castings with 17.39 kg 235 U/m, the pulsed experiments are more accurately analyzed by the αv -1 method, and measurements for both 7-assembly hexagonal and 2 x 3 square pitch lattices are compared with KENO-IV calculations

  18. Production of active lysozyme films by matrix assisted pulsed laser evaporation at 355 nm

    DEFF Research Database (Denmark)

    Purice, Andreea; Schou, Jørgen; Kingshott, P.

    2007-01-01

    Thin lysozyme films have been produced in a dry environment by MAPLE (matrix assisted pulsed laser evaporation) from a water ice matrix irradiated by laser light at 355 nm above the absorption threshold of the protein. A significant part of the lysozyme molecules are transferred to the film without...

  19. The minimum amount of "matrix " needed for matrix-assisted pulsed laser deposition of biomolecules

    DEFF Research Database (Denmark)

    Tabetah, Marshall; Matei, Andreea; Constantinescu, Catalin

    2014-01-01

    The ability of matrix-assisted pulsed laser evaporation (MAPLE) technique to transfer and deposit high-quality thin organic, bioorganic, and composite films with minimum chemical modification of the target material has been utilized in numerous applications. One of the outstanding problems in MAPLE...

  20. Processing of C60 thin films by Matrix-Assisted Pulsed Laser Evaporation (MAPLE)

    DEFF Research Database (Denmark)

    Canulescu, Stela; Schou, Jørgen; Fæster, Søren

    2011-01-01

    Thin films of fullerenes (C60) were deposited onto silicon using matrix-assisted pulsed laser evaporation (MAPLE). The deposition was carried out from a frozen homogeneous dilute solution of C60 in anisole (0.67 wt%), and over a broad range of laser fluences, from 0.15 J/cm2 up to 3.9 J/cm2. MAPLE...

  1. Characterization of lysozyme films produced by matrix assisted pulsed laser evaporation (MAPLE)

    DEFF Research Database (Denmark)

    Purice, Andreea; Schou, Jørgen; Kingshott, Peter

    2007-01-01

    Thin lysozyme films of thickness up to more than 100 nm have been produced in a dry environment by MAPLE (matrix assisted pulsed laser evaporation) from a water ice matrix. Analysis of the films demonstrates that a significant part of the lysozyme molecules is transferred to the substrate without...

  2. Structural and optical properties of surface-hydrogenated silicon nanocrystallites prepared by reactive pulsed laser ablation

    International Nuclear Information System (INIS)

    Makino, Toshiharu; Inada, Mitsuru; Umezu, Ikurou; Sugimura, Akira

    2005-01-01

    Pulsed laser ablation (PLA) in an inert background gas is a promising technique for preparing Si nanoparticles. Although an inert gas is appropriate for preparing pure material, a reactive background gas can be used to prepare compound nanoparticles. We performed PLA in hydrogen gas to prepare hydrogenated silicon nanoparticles. The mean diameter of the primary particles measured using transmission electron microscopy was approximately 5 nm. The hydrogen content in the deposits was very high and estimated to be about 20%. The infrared absorption corresponding to Si-H n (n = 1, 2, 3) bonds on the surface were observed at around 2100 cm -1 . The Raman scattering peak corresponding to crystalline Si was observed, and that corresponding to amorphous Si was negligibly small. These results indicate that the Si nanoparticles were not an alloy of Si and hydrogen but Si nanocrystallite (nc-Si) covered by hydrogen or hydrogenated amorphous silicon. This means that PLA in reactive H 2 gas is a promising technique for preparing surface passivated nc-Si. The deposition mechanism and optical properties of the surface passivated silicon nanocrystallites are discussed

  3. Models of WO x films growth during pulsed laser deposition at elevated pressures of reactive gas

    Science.gov (United States)

    Gnedovets, A. G.; Fominski, V. Y.; Nevolin, V. N.; Romanov, R. I.; Fominski, D. V.; Soloviev, A. A.

    2017-12-01

    The films of tungsten oxides were prepared by pulsed laser ablation of W target in a reactive gas atmosphere (air of laboratory humidity). Optical analysis and ion signal measurements for the laser plume allowed to recognise a threshold gas pressure that suppresses the deposition of non-scattered atomic flux from the plume. When the pressure exceeds about 40 Pa, the films grow due to the deposition of species that could be formed in collisions of W atoms with reactive molecules (e.g., O2). Kinetic Monte Carlo method was used for modelling film growth. Comparison of the model structures with the experimentally prepared films has shown that the growth mechanism of ballistic deposition at a pressure of 40 Pa could be changed on the diffusion limited aggregation at a pressure of ~100 Pa. Thus, a cauliflower structure of the film transformed to a web-like structure. For good correlation of experimental and model structures of WO x , a dimension of structural elements in the model should coincide with W-O cluster size.

  4. Assessment of macrovascular endothelial function using pulse wave analysis and its association with microvascular reactivity in healthy subjects.

    Science.gov (United States)

    Ibrahim, N N I N; Rasool, A H G

    2017-08-01

    Pulse wave analysis (PWA) and laser Doppler fluximetry (LDF) are non-invasive methods of assessing macrovascular endothelial function and microvascular reactivity respectively. The aim of this study was to assess the correlation between macrovascular endothelial function assessed by PWA and microvascular reactivity assessed by LDF. 297 healthy and non-smoking subjects (159 females, mean age (±SD) 23.56 ± 4.54 years) underwent microvascular reactivity assessment using LDF followed by macrovascular endothelial function assessments using PWA. Pearson's correlation showed no correlation between macrovascular endothelial function and microvascular reactivity (r = -0.10, P = 0.12). There was no significant correlation between macrovascular endothelial function assessed by PWA and microvascular reactivity assessed by LDF in healthy subjects. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  5. Effect of applied voltage and inter-pulse delay in spark-assisted LIBS

    Science.gov (United States)

    Robledo-Martinez, A.; Sobral, H.; Garcia-Villarreal, A.

    2018-06-01

    We report the results obtained in an investigation on the effect of the time delay between the laser and electrical pulses in a spark-assisted laser-induced breakdown spectroscopy (LIBS) experiment. The electrical discharge is produced by the discharge of a charged coaxial cable. This arrangement produces a fast unipolar current pulse (500 ns) that applies high power ( 600 kW) to the laser ablation plasma. The delay between the laser pulse and the electric pulse can be controlled at will in order to find the optimal time in terms of enhancement of the emitted lines. It was found that the application of the high voltage pulse enhances the ionic lines emitted by up to two orders of magnitude. An additional enhancement by a factor of 2-4 can be obtained delaying the application of the electric pulse by a time of 0.6-20 μs. In the tests it was noticed that the ionic lines were found to be clearly responsive to increments in the applied electric energy while the neutral lines did so marginally. Our results show that the intensification of the lines is mainly due to reheating of the ablation plasma as the application of the electrical pulse increments the temperature of the ablation plasma by about 50%. It is demonstrated that the present technique is an efficient way of intensifying the lines emitted without incurring in additional damage to the sample.

  6. An experimental investigation of pulsed laser-assisted machining of AISI 52100 steel

    Science.gov (United States)

    Panjehpour, Afshin; Soleymani Yazdi, Mohammad R.; Shoja-Razavi, Reza

    2014-11-01

    Grinding and hard turning are widely used for machining of hardened bearing steel parts. Laser-assisted machining (LAM) has emerged as an efficient alternative to grinding and hard turning for hardened steel parts. In most cases, continuous-wave lasers were used as a heat source to cause localized heating prior to material removal by a cutting tool. In this study, an experimental investigation of pulsed laser-assisted machining of AISI 52100 bearing steel was conducted. The effects of process parameters (i.e., laser mean power, pulse frequency, pulse energy, cutting speed and feed rate) on state variables (i.e., material removal temperature, specific cutting energy, surface roughness, microstructure, tool wear and chip formation) were investigated. At laser mean power of 425 W with frequency of 120 Hz and cutting speed of 70 m/min, the benefit of LAM was shown by 25% decrease in specific cutting energy and 18% improvement in surface roughness, as compared to those of the conventional machining. It was shown that at constant laser power, the increase of laser pulse energy causes the rapid increase in tool wear rate. Pulsed laser allowed efficient control of surface temperature and heat penetration in material removal region. Examination of the machined subsurface microstructure and microhardness profiles showed no change under LAM and conventional machining. Continuous chips with more uniform plastic deformation were produced in LAM.

  7. Surface morphology of thin lysozyme films produced by matrix-assisted pulsed laser evaporation (MAPLE)

    DEFF Research Database (Denmark)

    Purice, Andreea; Schou, Jørgen; Pryds, Nini

    2007-01-01

    Thin films of the protein, lysozyme, have been deposited by the matrix-assisted pulsed laser evaporation (MAPLE) technique. Frozen targets of 0.3-1.0 wt.% lysozyme dissolved in ultrapure water were irradiated by laser light at 355 mn with a fluence of 2 J/cm(2). The surface quality of the thin....... The concentration of lysozyme in the ice matrix apparently does not play any significant role for the morphology of the film. The morphology obtained with MAPLE has been compared with results for direct laser irradiation of a pressed lysozyme sample (i.e. pulsed laser deposition (PLD)). (C) 2007 Elsevier B.V. All...

  8. Pulse Oximeter Derived Blood Pressure Measurement in Patients With a Continuous Flow Left Ventricular Assist Device.

    Science.gov (United States)

    Hellman, Yaron; Malik, Adnan S; Lane, Kathleen A; Shen, Changyu; Wang, I-Wen; Wozniak, Thomas C; Hashmi, Zubair A; Munson, Sarah D; Pickrell, Jeanette; Caccamo, Marco A; Gradus-Pizlo, Irmina; Hadi, Azam

    2017-05-01

    Currently, blood pressure (BP) measurement is obtained noninvasively in patients with continuous flow left ventricular assist device (LVAD) by placing a Doppler probe over the brachial or radial artery with inflation and deflation of a manual BP cuff. We hypothesized that replacing the Doppler probe with a finger-based pulse oximeter can yield BP measurements similar to the Doppler derived mean arterial pressure (MAP). We conducted a prospective study consisting of patients with contemporary continuous flow LVADs. In a small pilot phase I inpatient study, we compared direct arterial line measurements with an automated blood pressure (ABP) cuff, Doppler and pulse oximeter derived MAP. Our main phase II study included LVAD outpatients with a comparison between Doppler, ABP, and pulse oximeter derived MAP. A total of five phase I and 36 phase II patients were recruited during February-June 2014. In phase I, the average MAP measured by pulse oximeter was closer to arterial line MAP rather than Doppler (P = 0.06) or ABP (P < 0.01). In phase II, pulse oximeter MAP (96.6 mm Hg) was significantly closer to Doppler MAP (96.5 mm Hg) when compared to ABP (82.1 mm Hg) (P = 0.0001). Pulse oximeter derived blood pressure measurement may be as reliable as Doppler in patients with continuous flow LVADs. © 2016 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  9. Growth of thin films of low molecular weight proteins by matrix assisted pulsed laser evaporation (MAPLE)

    DEFF Research Database (Denmark)

    Matei, Andreea; Schou, Jørgen; Constantinescu, C.

    2011-01-01

    Thin films of lysozyme and myoglobin grown by matrix assisted pulsed laser evaporation (MAPLE) from a water ice matrix have been investigated. The deposition rate of these two low molecular weight proteins (lysozyme: 14307 amu and myoglobin: 17083 amu) exhibits a maximum of about 1–2 ng/cm2 per....... The results for lysozyme demonstrate that the fragmentation rate of the proteins during the MAPLE process is not influenced by the pH of the water solution prior to freezing....

  10. Huge increase in gas phase nanoparticle generation by pulsed direct current sputtering in a reactive gas admixture

    Science.gov (United States)

    Polonskyi, Oleksandr; Peter, Tilo; Mohammad Ahadi, Amir; Hinz, Alexander; Strunskus, Thomas; Zaporojtchenko, Vladimir; Biederman, Hynek; Faupel, Franz

    2013-07-01

    Using reactive DC sputtering in a gas aggregation cluster source, we show that pulsed discharge gives rise to a huge increase in deposition rate of nanoparticles by more than one order of magnitude compared to continuous operation. We suggest that this effect is caused by an equilibrium between slight target oxidation (during "time-off") and subsequent sputtering of Ti oxides (sub-oxides) at "time-on" with high power impulse.

  11. Study of sterilization-treatment in pure and N- doped carbon thin films synthesized by inductively coupled plasma assisted pulsed-DC magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Javid, Amjed [Center for Advanced Plasma Surface Technology (CAPST), NU-SKKU Joint Institute for Plasma Nano-Materials (IPNM), Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Department of Textile Processing, National Textile University, Faisalabad 37610 (Pakistan); Kumar, Manish, E-mail: manishk@skku.edu [Center for Advanced Plasma Surface Technology (CAPST), NU-SKKU Joint Institute for Plasma Nano-Materials (IPNM), Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Han, Jeon Geon, E-mail: hanjg@skku.edu [Center for Advanced Plasma Surface Technology (CAPST), NU-SKKU Joint Institute for Plasma Nano-Materials (IPNM), Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2017-01-15

    Highlights: • Pure and N-doped nanocrystallie carbon films are synthesized by ICP assisted pulsed DC plasma process. • ICP power induces the increase in average graphitic crystallite size from 4.86 nm to 6.42 nm. • Beneficial role of ICP source assistance to achieve high sputtering throughput (deposition rate ∼55 nm/min). • Post-sterilization electron-transport study shows N-doped carbon films having promising stability. - Abstract: Electrically-conductive nanocrystalline carbon films, having non-toxic and non-immunogenic characteristics, are promising candidates for reusable medical devices. Here, the pure and N- doped nanocrystalline carbon films are deposited by the assistance of inductively coupled plasma (ICP) in an unbalanced facing target pulsed-DC magnetron sputtering process. Through the optical emission spectroscopy study, the role of ICP assistance and N-doping on the reactive components/radicals during the synthesis is presented. The N-doping enhances the three fold bonding configurations by increasing the ionization and energies of the plasma species. Whereas, the ICP addition increases the plasma density to control the deposition rate and film structure. As a result, sputtering-throughput (deposition rate: 31–55 nm/min), electrical resistivity (4–72 Ωcm) and water contact angle (45.12°–54°) are significantly tailored. Electric transport study across the surface microchannel confirms the superiority of N-doped carbon films for sterilization stability over the undoped carbon films.

  12. Control of Reactive Species Generated by Low-frequency Biased Nanosecond Pulse Discharge in Atmospheric Pressure Plasma Effluent

    Science.gov (United States)

    Takashima, Keisuke; Kaneko, Toshiro

    2016-09-01

    The control of hydroxyl radical and the other gas phase species generation in the ejected gas through air plasma (air plasma effluent) has been experimentally studied, which is a key to extend the range of plasma treatment. Nanosecond pulse discharge is known to produce high reduced electric field (E/N) discharge that leads to efficient generation of the reactive species than conventional low frequency discharge, while the charge-voltage cycle in the low frequency discharge is known to be well-controlled. In this study, the nanosecond pulse discharge biased with AC low frequency high voltage is used to take advantages of these discharges, which allows us to modulate the reactive species composition in the air plasma effluent. The utilization of the gas-liquid interface and the liquid phase chemical reactions between the modulated long-lived reactive species delivered from the air plasma effluent could realize efficient liquid phase chemical reactions leading to short-lived reactive species production far from the air plasma, which is crucial for some plasma agricultural applications.

  13. Octane-Assisted Reverse Micellar Dyeing of Cotton with Reactive Dyes

    Directory of Open Access Journals (Sweden)

    Alan Yiu-lun Tang

    2017-12-01

    Full Text Available In this study, we investigated the computer colour matching (CCM of cotton fabrics dyed with reactive dye using the octane-assisted reverse micellar approach. The aim of this study is to evaluate the colour quality and compare the accuracy between CCM forecasting and simulated dyeing produced by conventional water-based dyeing and octane-assisted reverse micellar dyeing. First, the calibration of dyeing databases for both dyeing methods was established. Standard samples were dyed with known dye concentrations. Computer colour matching was conducted by using the colour difference formula of International Commission on Illumination (CIE L*a*b*. Experimental results revealed that the predicted concentrations were nearly the same as the expected known concentrations for both dyeing methods. This indicates that octane-assisted reverse micellar dyeing system can achieve colour matching as good as the conventional water-based dyeing system. In addition, when comparing the colour produced by the conventional water-based dyeing system and the octane-assisted reverse micellar dyeing system, the colour difference (ΔE is ≤1, which indicates that the reverse micellar dyeing system could be applied for industrial dyeing with CCM.

  14. Wave Intensity Analysis of Right Ventricular Function during Pulsed Operation of Rotary Left Ventricular Assist Devices.

    Science.gov (United States)

    Bouwmeester, J Christopher; Park, Jiheum; Valdovinos, John; Bonde, Pramod

    2018-05-29

    Changing the speed of left ventricular assist devices (LVADs) cyclically may be useful to restore aortic pulsatility; however, the effects of this pulsation on right ventricular (RV) function are unknown. This study investigates the effects of direct ventricular interaction by quantifying the amount of wave energy created by RV contraction when axial and centrifugal LVADs are used to assist the left ventricle. In 4 anesthetized pigs, pressure and flow were measured in the main pulmonary artery and wave intensity analysis was used to identify and quantify the energy of waves created by the RV. The axial pump depressed the intensity of waves created by RV contraction compared with the centrifugal pump. In both pump designs, there were only minor and variable differences between the continuous and pulsed operation on RV function. The axial pump causes the RV to contract with less energy compared with a centrifugal design. Diminishing the ability of the RV to produce less energy translates to less pressure and flow produced, which may lead to LVAD-induced RV failure. The effects of pulsed LVAD operation on the RV appear to be minimal during acute observation of healthy hearts. Further study is necessary to uncover the effects of other modes of speed modulation with healthy and unhealthy hearts to determine if pulsed operation will benefit patients by reducing LVAD complications.

  15. UV and RIR matrix assisted pulsed laser deposition of organic MEH-PPV films

    International Nuclear Information System (INIS)

    Toftmann, B.; Papantonakis, M.R.; Auyeung, R.C.Y.; Kim, W.; O'Malley, S.M.; Bubb, D.M.; Horwitz, J.S.; Schou, J.; Johansen, P.M.; Haglund, R.F.

    2004-01-01

    A comparative study of thin film production based on gentle laser-ablation techniques has been carried out with the luminescent polymer poly[2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylene vinylene]. Using a free-electron laser films were made by resonant infrared pulsed laser deposition (RIR-PLD). For the first time resonant infrared matrix assisted pulsed laser evaporation (RIR-MAPLE) was successfully demonstrated on a luminescent polymer system. In addition to this, an excimer laser has been used for UV-MAPLE depositions at 193 and 248-nm irradiation. Films deposited onto NaCl and quartz substrates were analyzed by Fourier transform infrared spectroscopy, UV-visible absorbance and photoluminescence. Photoluminescent material was deposited by RIR-MAPLE and 248-nm MAPLE, while the RIR-PLD and 193-nm-MAPLE depositions displayed the smoothest surfaces but did not show photoluminescence

  16. Characterization of ethylcellulose and hydroxypropyl methylcellulose thin films deposited by matrix-assisted pulsed laser evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Palla-Papavlu, A., E-mail: apalla@nipne.ro [National Institute for Lasers, Plasma and Radiation Physics, PO Box MG-36, Magurele, RO-077125 Bucharest (Romania); Rusen, L.; Dinca, V.; Filipescu, M. [National Institute for Lasers, Plasma and Radiation Physics, PO Box MG-36, Magurele, RO-077125 Bucharest (Romania); Lippert, T. [Paul Scherrer Institut, General Energy Research Department, 5232 Villigen PSI (Switzerland); Dinescu, M. [National Institute for Lasers, Plasma and Radiation Physics, PO Box MG-36, Magurele, RO-077125 Bucharest (Romania)

    2014-05-01

    In this study is reported the deposition of hydroxypropyl methylcellulose (HPMC) and ethylcellulose (EC) by matrix-assisted pulsed laser evaporation (MAPLE). Both HPMC and EC were deposited on silicon substrates using a Nd:YAG laser (266 nm, 5 ns laser pulse and 10 Hz repetition rate) and then characterized by atomic force microscopy and Fourier transform infrared spectroscopy. It was found that for laser fluences up to 450 mJ/cm{sup 2} the structure of the deposited HPMC and EC polymer in the thin film resembles to the bulk. Morphological investigations reveal island features on the surface of the EC thin films, and pores onto the HPMC polymer films. The obtained results indicate that MAPLE may be an alternative technique for the fabrication of new systems with desired drug release profile.

  17. Characterization of ethylcellulose and hydroxypropyl methylcellulose thin films deposited by matrix-assisted pulsed laser evaporation

    Science.gov (United States)

    Palla-Papavlu, A.; Rusen, L.; Dinca, V.; Filipescu, M.; Lippert, T.; Dinescu, M.

    2014-05-01

    In this study is reported the deposition of hydroxypropyl methylcellulose (HPMC) and ethylcellulose (EC) by matrix-assisted pulsed laser evaporation (MAPLE). Both HPMC and EC were deposited on silicon substrates using a Nd:YAG laser (266 nm, 5 ns laser pulse and 10 Hz repetition rate) and then characterized by atomic force microscopy and Fourier transform infrared spectroscopy. It was found that for laser fluences up to 450 mJ/cm2 the structure of the deposited HPMC and EC polymer in the thin film resembles to the bulk. Morphological investigations reveal island features on the surface of the EC thin films, and pores onto the HPMC polymer films. The obtained results indicate that MAPLE may be an alternative technique for the fabrication of new systems with desired drug release profile.

  18. UV and RIR matrix assisted pulsed laser deposition of organic MEH-PPV films

    DEFF Research Database (Denmark)

    Christensen, Bo Toftmann; Papantonalis, M.R.; Auyeung, R.C.Y.

    2004-01-01

    -PLD). For the first time resonant infrared matrix assisted pulsed laser evaporation (RIR-MAPLE) was successfully demonstrated on a luminescent polymer system. In addition to this, an excimer laser has been used for UV-MAPLE depositions at 193 and 248-nm irradiation. Films deposited onto NaCl and quartz substrates......A comparative study of thin film production based on gentle laser-ablation techniques has been carried out with the luminescent polymer poly [2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylene vinylene]. Using a free-electron laser films were made by resonant infrared pulsed laser deposition (RIR...... were analyzed by Fourier transform infrared spectroscopy, UV-visible absorbance and photoluminescence. Photoluminescent material was deposited by RIR-MAPLE and 248-nm MAPLE, while the RIR-PLD and 193-nm-MAPLE depositions displayed the smoothest surfaces but did not show photoluminescence. (C) 2003...

  19. Effects of gamma irradiations on reactive pulsed laser deposited vanadium dioxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Madiba, I.G., E-mail: madibagiven@gmail.com [UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, P O Box 392, Pretoria (South Africa); Empa, Swiss Federal Laboratories Materials Science and Technology, CH-8600 Dübendorf (Switzerland); Émond, N.; Chaker, M. [Institut National de la Recherche Scientifique (INRS),1650 Blvd. Lionel-Boulet, Varennes, Québec J3X1S2 (Canada); Thema, F.T. [UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, P O Box 392, Pretoria (South Africa); iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); Tadadjeu, S.I. [iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); Department of Electrical, Electronics and Computer Engineering, French South African Institute of Technology/Cape Peninsula University of Technology, Bellville campus, PO Box 1906, Bellville, 7530 (South Africa); Muller, U.; Zolliker, P. [Empa, Swiss Federal Laboratories Materials Science and Technology, CH-8600 Dübendorf (Switzerland); Braun, A. [ETH Zurich, Swiss Federal Institute of Technology, CH-8057, Zurich (Switzerland); Empa, Swiss Federal Laboratories Materials Science and Technology, CH-8600 Dübendorf (Switzerland); Kotsedi, L. [iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); and others

    2017-07-31

    Highlights: • Synthesis of VO{sub 2} thin films by Reactive pulsed laser deposition has been achieved. • Properties VO{sub 2} remain mainly unaffected when subjected to gamma ray doses similar to those encountered during space missions. • The long range crystal structure of VO{sub 2} remains intact upon irradiation on different doses up to 100 kGy. • XPS reveals a shift from V{sup 4+} to V{sup 5+} oxidation state upon irradiation, due to the frenkel pair formation on the surface. • Irradiated films show the characteristic SMT of VO{sub 2}, although the electrical and optical properties are slightly affected. - Abstract: Vanadium oxide films are considered suitable coatings for various applications such as thermal protective coating of small spacecrafts because of their thermochromic properties. While in outer space, such coating will be exposed to cosmic radiations which include γ-rays. To study the effect of these γ-rays on the coating properties, we have deposited vanadium dioxide (VO{sub 2}) films on silicon substrates and subjected them to extensive γ-irradiations with typical doses encountered in space missions. The prevalent crystallographic phase after irradiation remains the monoclinic VO{sub 2} phase but the films preferential orientation shifts to lower angles due to the presence of disordered regions caused by radiations. Raman spectroscopy measurements also evidences that the VO{sub 2} structure is slightly affected by gamma irradiation. Indeed, increasing the gamma rays dose locally alters the crystalline and electronic structures of the films by modifying the V–V inter-dimer distance, which in turns favours the presence of the VO{sub 2} metallic phase. From the XPS measurements of V2p and O1s core level spectra, an oxidation of vanadium from V{sup 4+} towards V{sup 5+} is revealed. The data also reveal a hydroxylation upon irradiation which is corroborated by the vanishing of a low oxidation state peak near the Fermi energy in the

  20. Layered double hydroxides/polymer thin films grown by matrix assisted pulsed laser evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Birjega, R.; Matei, A.; Mitu, B.; Ionita, M.D.; Filipescu, M.; Stokker-Cheregi, F.; Luculescu, C.; Dinescu, M. [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 77125 Bucharest–Magurele (Romania); Zavoianu, R.; Pavel, O.D. [University of Bucharest, Faculty of Chemistry, Department of Chemical Technology and Catalysis, 4-12 Regina Elisabeta Bd., Bucharest (Romania); Corobea, M.C. [National R. and S. Institute for Chemistry and Petrochemistry, ICECHIM, 202 Splaiul Independentei Str., CP-35-274, 060021, Bucharest (Romania)

    2013-09-30

    Due to their highly tunable properties, layered double hydroxides (LDHs) are an emerging class of the favorably layered crystals used for the preparation of multifunctional polymer/layered crystal nanocomposites. In contrast to cationic clay materials with negatively charge layers, LDHs are the only host lattices with positively charged layers (brucite-like), with interlayer exchangeable anions and intercalated water. In this work, the deposition of thin films of Mg and Al based LDH/polymers nanocomposites by laser techniques is reported. Matrix assisted pulsed laser evaporation was the method used for thin films deposition. The Mg–Al LDHs capability to act as a host for polymers and to produce hybrid LDH/polymer films has been investigated. Polyethylene glycol with different molecular mass compositions and ethylene glycol were used as polymers. The structure and surface morphology of the deposited LDH/polymers films were examined by X-ray diffraction, Fourier transform infra-red spectroscopy, atomic force microscopy and scanning electron microscopy. - Highlights: • Hybrid composites deposited by matrix assisted pulsed laser evaporation (MAPLE). • Mg–Al layered double hydroxides (LDH) and polyethylene glycol (PEG) are used. • Mixtures of PEG1450 and LDH were deposited by MAPLE. • Deposited thin films preserve the properties of the starting material. • The film wettability can be controlled by the amount of PEG.

  1. Effect of deposition parameters on properties of ITO films prepared by reactive middle frequency pulsed dual magnetron sputtering

    International Nuclear Information System (INIS)

    Rogozin, A.I.; Vinnichenko, M.V.; Kolitsch, A.; Moeller, W.

    2004-01-01

    ITO layers with low resistivity and high visible transmittance were produced by means of middle frequency reactive dual magnetron sputtering. The influence of base pressure, Ar/O 2 ratio and magnetron pulse duration on the film composition, structure, electrical, and optical properties has been investigated. The deposition rate is proportional to the magnetron operation power at changing pulse duration and constant Ar and O 2 flows. At enhanced O 2 flows an onset of the magnetron target oxidation is discussed as a reason for the decrease of the deposition rate. The presence of water vapor in the residual gas is determined to be a reason for deterioration of resistivity and optical transmittance observed for ITO films produced at a base pressures higher than 5·10 -4 Pa. It is demonstrated that spectroscopic ellipsometry can be used as a noncontact tool to monitor the resistivity of ITO films

  2. Properties of amorphous silicon thin films synthesized by reactive particle beam assisted chemical vapor deposition

    International Nuclear Information System (INIS)

    Choi, Sun Gyu; Wang, Seok-Joo; Park, Hyeong-Ho; Jang, Jin-Nyoung; Hong, MunPyo; Kwon, Kwang-Ho; Park, Hyung-Ho

    2010-01-01

    Amorphous silicon thin films were formed by chemical vapor deposition of reactive particle beam assisted inductively coupled plasma type with various reflector bias voltages. During the deposition, the substrate was heated at 150 o C. The effects of reflector bias voltage on the physical and chemical properties of the films were systematically studied. X-ray diffraction and Raman spectroscopy results showed that the deposited films were amorphous and the films under higher reflector voltage had higher internal energy to be easily crystallized. The chemical state of amorphous silicon films was revealed as metallic bonding of Si atoms by using X-ray photoelectron spectroscopy. An increase in reflector voltage induced an increase of surface morphology of films and optical bandgap and a decrease of photoconductivity.

  3. The determination of reactivity at a compact core with low absorption reflector by means of the pulsed neutron method

    International Nuclear Information System (INIS)

    Hecker, R.; Drueke, V.; Ahmad, S.K.; Kacmary, S.; Paul, N.

    1976-09-01

    Pulsed measurements at a compact critical facility with low absorption reflector are described. By a number of such measurements at different points of the system a proper value for the reactivity can be determined, which allows a meaningful comparison with values calculated by static computer codes in spite of the presence of kinetic distortion in the system. A modified area ratio method is developed and applied to the measurements; furthermore a method is shown, which allows to suppress in this systems the kinetic distortion in the fundamental mode by application of special detectors. (orig.) [de

  4. On the estimation of subcritical reactivity by the pulsed α-method

    International Nuclear Information System (INIS)

    Shulepin, V.S.

    1974-01-01

    A technique for calculating the neutron generation time is considered. It is based on the use of only basic (non-conjugate) conditionally critical reactor equations. The formula is drawn to show the relation between the reactivity coefficient Ksub(eff), damping decrement and neutron generation time. Some transformations result in a conditionally critical equation at Ksub(eff) equal to unit, from which the neutron generation time is found that is necessary to measure subcritical reactivity by the α-method

  5. Growth and characterization of polycrystalline Ge{sub 1-x}C{sub x} by reactive pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez, M.P., E-mail: mayrap@fisica.uh.cu [Instituto de Ciencia y Tecnologia de Materiales, Zapata y G, P.O. Box 10400, Universidad de La Habana (Cuba); Farias, M.H.; Castillon, F.F.; Diaz, Jesus A.; Avalos, M. [Centro de Nanociencias y Nanotecnologia, Universidad Nacional Autonoma de Mexico, Km 107 Carretera Tijuana-Ensenada, C.P. 22800 Ensenada, Baja California (Mexico); Ulloa, L. [Universidad de Guadalajara, (CUCEI) Blvd. Marcelino Garcia Barragan 1421, C.P. 44430 Guadalajara, Jalisco (Mexico); Gallegos, J.A.; Yee-Madeiros, H. [Escuela Superior de Fisica y Matematicas-IPN, UP' ALM' , Colonia Lindavista 07738 (Mexico)

    2011-03-15

    Polycrystalline thin films of Ge-C were grown on Si (1 1 1) substrates by means of reactive pulsed laser deposition with methane pressure of 100 mTorr. Effect substrate temperature, T{sub s}, on C incorporation to substitutional sites (x) in Ge{sub 1-x}C{sub x} was investigated systematically by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyzes. The substrate temperatures were ranging from 250 to 400 deg. C. The substitutional C composition x in the films by XRD were estimated using the Vegard's linear law. The maximum value of x calculated by XRD was 0.032 for T{sub s} of 350 deg. C. The position of the C 1s peak at 283.4 eV in the XPS spectrum confirmed the germanium-carbon alloys. XRD measurements indicated that x increased with T{sub s} from 250 deg. C to 350 deg. C. At T{sub s} = 400 deg. C, the estimation of x was lowered. However, the C content calculated by XPS analyzes increased with T{sub s} being more these values than substitutional C composition x. XPS and XRD analyzes demonstrate that the remaining C atoms are incorporated to interstitial sites. The use of the T{sub s} plays important roles in the incorporation of substitutional C and in restraining C-cluster formation in the reactive pulsed laser deposition growth of Ge-C/Si.

  6. Optical, electrical and mechanical properties of the tantalum oxynitride thin films deposited by pulsing reactive gas sputtering

    International Nuclear Information System (INIS)

    Le Dreo, H.; Banakh, O.; Keppner, H.; Steinmann, P.-A.; Briand, D.; Rooij, N.F. de

    2006-01-01

    Thin films of tantalum oxynitride were prepared by reactive magnetron sputtering using a Ta target and N 2 and O 2 as reactive gases. The nitrogen flow was kept constant while the oxygen flow was pulsed periodically. The film composition evolves progressively from TaO 0.25 N 1.51 to TaO 2.42 N 0.25 while increasing the oxygen pulse duty cycle without any abrupt change in the elemental content. The optical transmission spectra of the films deposited on glass show a 'blue shift' of the absorption edge with increasing oxygen content. X-ray diffraction (XRD) patterns of all films exhibit broad peaks typical for nanocrystalline materials. Cross-section film morphology is rather featureless and surface topography is smooth exhibiting very small grains, in agreement with the results obtained by XRD. The optical properties of the films are very sensitive to their chemical composition. All films exhibit semiconducting behaviour with an optical band gap changing from 1.85 to 4.0 eV with increasing oxygen content. In order to evaluate the potential of the tantalum oxynitride films for microelectronic applications some Ta-O-N films were integrated in a MOS structure. The results of the capacitance-voltage measurements of the system Al//Ta-O-N//p-Si are discussed with respect to the chemical composition of the Ta-O-N films

  7. Launch and capture of a single particle in a pulse-laser-assisted dual-beam fiber-optic trap

    Science.gov (United States)

    Fu, Zhenhai; She, Xuan; Li, Nan; Hu, Huizhu

    2018-06-01

    The rapid loading and manipulation of microspheres in optical trap is important for its applications in optomechanics and precision force sensing. We investigate the microsphere behavior under coaction of a dual-beam fiber-optic trap and a pulse laser beam, which reveals a launched microsphere can be effectively captured in a spatial region. A suitable order of pulse duration for launch is derived according to the calculated detachment energy threshold of pulse laser. Furthermore, we illustrate the effect of structural parameters on the launching process, including the spot size of pulse laser, the vertical displacement of beam waist and the initial position of microsphere. Our result will be instructive in the optimal design of the pulse-laser-assisted optical tweezers for controllable loading mechanism of optical trap.

  8. Functionalized porphyrin conjugate thin films deposited by matrix assisted pulsed laser evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Iordache, S. [University of Bucharest, 3Nano-SAE Research Center, PO Box MG-38, Bucharest-Magurele (Romania); Cristescu, R., E-mail: rodica.cristescu@inflpr.ro [National Institute for Lasers, Plasma and Radiation Physics, Lasers Department, P.O. Box MG-36, Bucharest-Magurele (Romania); Popescu, A.C.; Popescu, C.E.; Dorcioman, G.; Mihailescu, I.N. [National Institute for Lasers, Plasma and Radiation Physics, Lasers Department, P.O. Box MG-36, Bucharest-Magurele (Romania); Ciucu, A.A. [University of Bucharest, Faculty of Chemistry, Bucharest (Romania); Balan, A.; Stamatin, I. [University of Bucharest, 3Nano-SAE Research Center, PO Box MG-38, Bucharest-Magurele (Romania); Fagadar-Cosma, E. [Institute of Chemistry Timisoara of Romanian Academy, M. Viteazul Ave. 24, 300223-Timisoara (Romania); Chrisey, D.B. [Tulane University, Departments of Physics and Biomedical Engineering, New Orleans, LA 70118 (United States)

    2013-08-01

    We report on the deposition of nanostructured porphyrin-base, 5(4-carboxyphenyl)-10,15,20-tris(4-phenoxyphenyl)-porphyrin thin films by matrix assisted pulsed laser evaporation onto silicon substrates with screen-printed electrodes. AFM investigations have shown that at 400 mJ/cm{sup 2} fluence a topographical transition takes place from the platelet-like stacking porphyrin-based nanostructures in a perpendicular arrangement to a quasi-parallel one both relative to the substrate surface. Raman spectroscopy has shown that the chemical structure of the deposited thin films is preserved for fluences within the range of 200–300 mJ/cm{sup 2}. Cyclic voltammograms have demonstrated that the free porphyrin is appropriate as a single mediator for glucose in a specific case of screen-printed electrodes, suggesting potential for designing a new class of biosensors.

  9. Growth of thin fullerene films by matrix assisted pulsed laser evaporation

    DEFF Research Database (Denmark)

    Canulescu, Stela; Schou, Jørgen; Fæster, Søren

    C60 fullerene thin films of average thickness of more than 100 nm on silicon substrates can be produced in vacuum by matrix-assisted pulsed laser evaporation (MAPLE). A 355 nm Nd:YAG laser was directed onto a frozen target of anisole with a concentration of 0.67 wt% C60. At laser fluences below 1.......5 J/cm2 the dominant fraction of the film molecules are C60 transferred to the substrate without any fragmentation. For high fluences high-resolution SEM images of MAPLE deposited films reveal large circular features on the surface with high amount of material concentrated at edges. These features......, observed over a wide range of laser fluences, are caused by ejection of large matrix-fullerene liquid droplets into the gas-phase and subsequent deposition. At similar laser energies, but using an unfocused laser beam, MAPLE favours evaporation of matrix and organic molecules, resulting in films...

  10. Matrix Assisted Pulsed Laser Evaporation for growth of fullerene thin films

    DEFF Research Database (Denmark)

    Canulescu, Stela; Schou, Jørgen; Fæster Nielsen, Søren

    C60 fullerene thin films of average thickness of more than 100 nm can be produced in vacuum by matrix-assisted pulsed laser evaporation (MAPLE). A 355 nm Nd:YAG laser was directed onto a frozen target of anisole with a concentration of 0.67 wt% C60. At laser fluences below 1.5 J/cm2, a dominant...... fraction of the film molecules are C60 transferred to the substrate without any fragmentation. Highresolution SEM images of MAPLE deposited films reveal large circular droplets on the surface with high amount of material concentrated at edges (Fig. 1A). These features, observed over a wide range of laser...... fluences, are caused by ejection of large matrix-fullerene liquid droplets into the gas-phase and subsequent deposition. At similar laser energies, but using an unfocused laser beam, MAPLE favours evaporation of matrix and organic molecules, resulting in production of films with smooth surfaces and minimal...

  11. Pulsed electric field-assisted modification of pectin from sugar beet pulp.

    Science.gov (United States)

    Ma, Sen; Wang, Zhong-he

    2013-02-15

    This current work is concerned with the modification of sugar beet pulp (SBP) pectin assisted by pulsed electric filed (PEF) without solvent. Pectin-arachates with degree of esterification (DE) ranging from 49 to 84 were prepared in one-step modification. The results showed that the DE of pectin derivatives increased significantly with the PEF intensity from 18 to 30 kV cm((1) and total specific energy input from 124 to 345 J mL((1). Evidence of modification of pectin was provided by FT-IR, X-ray diffraction patterns and NMR spectra. Thermogravimetric investigation of modified pectin indicated a higher thermal stability than the untreated one. Results revealed that PEF technology is a promising method for industrial manufacture of pectin derivatives. Copyright © 2012 Elsevier Ltd. All rights reserved.

  12. Re-activation of degraded nickel cermet anodes - Nano-particle formation via reverse current pulses

    DEFF Research Database (Denmark)

    Hauch, Anne; Marchese, M.; Lanzini, A.

    2018-01-01

    The Ni/yttria-stabilized-zirconia (YSZ) cermet is the most commonly applied fuel electrode for solid oxide cells (SOCs). Loss of Ni/YSZ electrode activity is a key life-time limiting factor of the SOC. Developing means to mitigate this loss of performance or re-activate a fuel electrode is theref......The Ni/yttria-stabilized-zirconia (YSZ) cermet is the most commonly applied fuel electrode for solid oxide cells (SOCs). Loss of Ni/YSZ electrode activity is a key life-time limiting factor of the SOC. Developing means to mitigate this loss of performance or re-activate a fuel electrode...

  13. Reactivity of OH and O– with aqueous methyl viologen studied by pulse radiolysis

    DEFF Research Database (Denmark)

    Solar, Sonja; Solar, Wolfgang; Getoff, Nikola

    1985-01-01

    The behaviour of aqueous MV2+ towards oxidizing radicals (OH and O–) has been investigated in the pH range from 6 to 14 by means of pulse radiolysis. A semi-linear optimization method was applied for resolving the complex reaction mechanism. In the pH range from 6 to 8 the rate constant for attac...

  14. Nanoparticle Thin Films for Gas Sensors Prepared by Matrix Assisted Pulsed Laser Evaporation

    Directory of Open Access Journals (Sweden)

    Roberto Rella

    2009-04-01

    Full Text Available The matrix assisted pulsed laser evaporation (MAPLE technique has been used for the deposition of metal dioxide (TiO2, SnO2 nanoparticle thin films for gas sensor applications. For this purpose, colloidal metal dioxide nanoparticles were diluted in volatile solvents, the solution was frozen at the liquid nitrogen temperature and irradiated with a pulsed excimer laser. The dioxide nanoparticles were deposited on Si and Al2O3 substrates. A rather uniform distribution of TiO2 nanoparticles with an average size of about 10 nm and of SnO2 nanoparticles with an average size of about 3 nm was obtained, as demonstrated by high resolution scanning electron microscopy (SEM-FEG inspections. Gas-sensing devices based on the resistive transduction mechanism were fabricated by depositing the nanoparticle thin films onto suitable rough alumina substrates equipped with interdigitated electrical contacts and heating elements. Electrical characterization measurements were carried out in controlled environment. The results of the gas-sensing tests towards low concentrations of ethanol and acetone vapors are reported. Typical gas sensor parameters (gas responses, response/recovery time, sensitivity, and low detection limit towards ethanol and acetone are presented.

  15. Nanoparticle thin films for gas sensors prepared by matrix assisted pulsed laser evaporation.

    Science.gov (United States)

    Caricato, Anna Paola; Luches, Armando; Rella, Roberto

    2009-01-01

    The matrix assisted pulsed laser evaporation (MAPLE) technique has been used for the deposition of metal dioxide (TiO(2), SnO(2)) nanoparticle thin films for gas sensor applications. For this purpose, colloidal metal dioxide nanoparticles were diluted in volatile solvents, the solution was frozen at the liquid nitrogen temperature and irradiated with a pulsed excimer laser. The dioxide nanoparticles were deposited on Si and Al(2)O(3) substrates. A rather uniform distribution of TiO(2) nanoparticles with an average size of about 10 nm and of SnO(2) nanoparticles with an average size of about 3 nm was obtained, as demonstrated by high resolution scanning electron microscopy (SEM-FEG) inspections. Gas-sensing devices based on the resistive transduction mechanism were fabricated by depositing the nanoparticle thin films onto suitable rough alumina substrates equipped with interdigitated electrical contacts and heating elements. Electrical characterization measurements were carried out in controlled environment. The results of the gas-sensing tests towards low concentrations of ethanol and acetone vapors are reported. Typical gas sensor parameters (gas responses, response/recovery time, sensitivity, and low detection limit) towards ethanol and acetone are presented.

  16. Protein-resistant polymer coatings obtained by matrix assisted pulsed laser evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Rusen, L. [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Street, PO Box MG-16, 077125, Magurele, Bucharest (Romania); Mustaciosu, C. [Horia Hulubei National Institute of Physics and Nuclear Engineering - IFIN HH, Magurele, Bucharest (Romania); Mitu, B.; Filipescu, M.; Dinescu, M. [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Street, PO Box MG-16, 077125, Magurele, Bucharest (Romania); Dinca, V., E-mail: dinali@nipne.ro [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Street, PO Box MG-16, 077125, Magurele, Bucharest (Romania)

    2013-08-01

    Adsorption of proteins and polysaccharides is known to facilitate microbial attachment and subsequent formation of biofilm on surfaces that ultimately results in its biofouling. Therefore, protein repellent modified surfaces are necessary to block the irreversible attachment of microorganisms. Within this context, the feasibility of using the Poly(ethylene glycol)-block-poly(ε-caprolactone) methyl ether (PEG-block-PCL Me) copolymer as potential protein-resistant coating was explored in this work. The films were deposited using Matrix Assisted Pulsed Laser Evaporation (MAPLE), a technique that allows good control of composition, thickness and homogeneity. The chemical and morphological characteristics of the films were examined using Fourier Transform Infrared Spectroscopy (FTIR), contact angle measurements and Atomic Force Microscopy (AFM). The FTIR data demonstrates that the functional groups in the MAPLE-deposited films remain intact, especially for fluences below 0.5 J cm{sup −2}. Optical Microscopy and AFM images show that the homogeneity and the roughness of the coatings are related to both laser parameters (fluence, number of pulses) and target composition. Protein adsorption tests were performed on the PEG-block-PCL Me copolymer coated glass and on bare glass surface as a control. The results show that the presence of copolymer as coating significantly reduces the adsorption of proteins.

  17. Effect of reactive atmosphere on pulsed laser deposition of hydroxyapatite thin films

    Czech Academy of Sciences Publication Activity Database

    Mroz, W.; Jedynski, M.; Hoffman, J.; Jelínek, Miroslav; Major, B.; Prokopiuk, A.; Szymanski, Z.

    2007-01-01

    Roč. 59, - (2007), s. 720-723 ISSN 1742-6588 Grant - others:PBZ-KBN(PL) 100/TO8/2003 and 0028/TOO/2005/29 Institutional research plan: CEZ:AV0Z10100522 Keywords : PLD * hydroxyapatite * reactive atmosphere * thin layers Subject RIV: BM - Solid Matter Physics ; Magnetism

  18. Treatment of Hemorrhagic Vocal Polyps by Pulsed Dye Laser-Assisted Laryngomicrosurgery

    Directory of Open Access Journals (Sweden)

    Hyung Kwon Byeon

    2015-01-01

    Full Text Available Objective. Conventional surgical techniques of laryngomicrosurgery (LMS on hemorrhagic vocal polyps are often difficult due to obscuration of the surgical field by inadvertent bleeding from the lesion, and there are often significant amounts of mucosal epithelium loss. Here, we introduce our surgical technique using pulsed dye laser (PDL, which can effectively resect the polyp with vocal fold mucosa preservation. Methods. Patients who were diagnosed with hemorrhagic vocal polyp and who were surgically managed using PDL from March 2013 to October 2014 were retrospectively reviewed. Preoperative and postoperative clinical outcomes and surgical findings were evaluated. Results. A total of 39 patients were treated with PDL-assisted enucleation LMS. The average age was 43.7 years (range 20–73, and there were 20 males and 19 females (17 professional voice users. In all cases, the hemorrhagic polyp was successfully enucleated after application of PDL, thereby preserving the overlying epithelium. Postoperative voice outcomes were favorable with clear preservation of the vocal fold mucosal wave. Conclusion. PDL-assisted enucleation LMS for the treatment of hemorrhagic vocal polyps can be a safe and effective surgical technique. It can be considered a promising treatment option for hemorrhagic vocal polyps.

  19. Selective Oxidation and Reactive Wetting during Galvanizing of a CMnAl TRIP-Assisted Steel

    Science.gov (United States)

    Bellhouse, E. M.; McDermid, J. R.

    2011-09-01

    A transformation induced plasticity (TRIP)-assisted steel with 0.2 pct C, 1.5 pct Mn, and 1.5 pct Al was successfully galvanized using a thermal cycle previously shown to produce an excellent combination of strength and ductility. The steel surface chemistry and oxide morphology were determined as a function of process atmosphere oxygen partial pressure. For the 220 K (-53 °C) dew point (dp) + 20 pct H2 atmosphere, the oxide morphology was a mixture of films and nodules. For the 243 K (-30 °C) dp + 5 pct H2 atmosphere, nodules of MnO were found primarily at grain boundaries. For the 278 K (+5 °C) dp + 5 pct H2 atmosphere, nodules of metallic Fe were found on the surface as a result of alloy element internal oxidation. The steel surface chemistry and oxide morphology were then related to the reactive wetting behavior during continuous hot dip galvanizing. Good wetting was obtained using the two lower oxygen partial pressure process atmospheres [220 K dp and 243 K dp (-53 °C dp and -30 °C dp)]. An increase in the number of bare spots was observed when using the higher oxygen partial pressure process atmosphere (+5 °C dp) due to the increased thickness of localized oxide films.

  20. Surface morphology of polyethylene glycol films produced by matrix-assisted pulsed laser evaporation (MAPLE): Dependence on substrate temperature

    DEFF Research Database (Denmark)

    Rodrigo, K.; Czuba, P.; Toftmann, B.

    2006-01-01

    The dependence of the surface morphology on the substrate temperature during film deposition was investigated for polyethylene glycol (PEG) films by matrix-assisted pulsed laser evaporation (MAPLE). The surface structure was studied with a combined technique of optical imaging and AFM measurements...

  1. Re-activation of degraded nickel cermet anodes - Nano-particle formation via reverse current pulses

    Science.gov (United States)

    Hauch, A.; Marchese, M.; Lanzini, A.; Graves, C.

    2018-02-01

    The Ni/yttria-stabilized-zirconia (YSZ) cermet is the most commonly applied fuel electrode for solid oxide cells (SOCs). Loss of Ni/YSZ electrode activity is a key life-time limiting factor of the SOC. Developing means to mitigate this loss of performance or re-activate a fuel electrode is therefore important. In this work, we report a series of five tests on state-of-the-art Ni/YSZ-YSZ-CGObarrier-LSC/CGO cells. All cells were deliberately degraded via gas stream impurities in CO2/CO or harsh steam electrolysis operation. The cells were re-activated via a variety of reverse current treatments (RCTs). Via electrochemical impedance spectroscopy, we found that the Ni/YSZ electrode performance could be recovered via RCT, but not via constant fuel cell operation. For optimized RCT, we obtained a lower Ni/YSZ electrode resistance than the initial resistance. E.g. at 700 °C we measured fuel electrode resistance of 180 mΩ cm2, 390 mΩ cm2, and 159 mΩ cm2 before degradation, after degradation and after re-activation via RCT, respectively. Post-test SEM revealed that the RCT led to formation of nano-particles in the fuel electrode. Besides the remarkable improvement, the results also showed that RCTs can weaken Ni/YSZ interfaces and the electrode/electrolyte interface. This indicates that finding an optimum RCT profile is crucial for achieving maximum benefit.

  2. Deposition of PZT thin film onto copper-coated polymer films by mean of pulsed-DC and RF-reactive sputtering

    Czech Academy of Sciences Publication Activity Database

    Suchaneck, G.; Labitzke, R.; Adolphi, B.; Jastrabík, Lubomír; Adámek, Petr; Drahokoupil, Jan; Hubička, Zdeněk; Kiselev, D.A.; Kholkin, A. L.; Gerlach, G.; Dejneka, Alexandr

    2011-01-01

    Roč. 205, č. 2 (2011), S241-S244 ISSN 0257-8972 R&D Projects: GA ČR GC202/09/J017; GA AV ČR KAN301370701; GA MŠk(CZ) 1M06002 Institutional research plan: CEZ:AV0Z10100522 Keywords : pulsed DC reactive sputtering * RF reactive sputtering * complex oxide film deposition * polymer substrate Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.867, year: 2011

  3. Interface description using computational methods and tribological characteristic of Ti N/Ti C films prepared by reactive pulse arc evaporation technique

    International Nuclear Information System (INIS)

    Devia N, D. M.; Gonzalez C, J. M.; Ruden M, A.

    2013-01-01

    The Ti N/Ti C bilayers have been deposited by Plasma Assisted Physical Vapor Deposition Technique - Reactive Pulsed Arc. The coatings were analyzed by X-ray photoelectron spectroscopy (XP S) and X-ray diffraction (XRD). From the signal treatment of the narrow XP S spectra and the XRD diffraction patterns, the formation of Ti N (titanium nitride), Ti C (titanium carbide) and Ti CN (titanium carbonitride) was confirmed, with fm-3m spatial group, corresponding to the Fcc phase of the synthesized compounds. The multilayer was simulated using Density Functional Theory (DFT) by the Unrestricted Hartree Fock method. Charge distributions and electron total density were obtained; finding bond formation at the interphase, electrical neutrality and system stability. Anomalies in the corners of the structures due to edge effect, simulation ideality and the no internal tension inclusion, intrinsic to the growing, are observed. The ball on disc tribometer was used to measure the friction and wear coefficient to verify the interface formation. (Author)

  4. Interface description using computational methods and tribological characteristic of Ti N/Ti C films prepared by reactive pulse arc evaporation technique

    Energy Technology Data Exchange (ETDEWEB)

    Devia N, D. M. [Universidad Nacional de Colombia, Sede Manizales, Campus La Nubia, Manizales, Caldas (Colombia); Gonzalez C, J. M.; Ruden M, A., E-mail: dmdevian@utp.edu.co [Universidad del Valle, Edificio 349, espacio 1003, Ciudad Universitaria Melendez, Cali (Colombia)

    2013-10-01

    The Ti N/Ti C bilayers have been deposited by Plasma Assisted Physical Vapor Deposition Technique - Reactive Pulsed Arc. The coatings were analyzed by X-ray photoelectron spectroscopy (XP S) and X-ray diffraction (XRD). From the signal treatment of the narrow XP S spectra and the XRD diffraction patterns, the formation of Ti N (titanium nitride), Ti C (titanium carbide) and Ti CN (titanium carbonitride) was confirmed, with fm-3m spatial group, corresponding to the Fcc phase of the synthesized compounds. The multilayer was simulated using Density Functional Theory (DFT) by the Unrestricted Hartree Fock method. Charge distributions and electron total density were obtained; finding bond formation at the interphase, electrical neutrality and system stability. Anomalies in the corners of the structures due to edge effect, simulation ideality and the no internal tension inclusion, intrinsic to the growing, are observed. The ball on disc tribometer was used to measure the friction and wear coefficient to verify the interface formation. (Author)

  5. Stress and piezoelectric properties of aluminum nitride thin films deposited onto metal electrodes by pulsed direct current reactive sputtering

    International Nuclear Information System (INIS)

    Dubois, Marc-Alexandre; Muralt, Paul

    2001-01-01

    Polycrystalline aluminum nitride thin films were deposited onto platinum, aluminum, and titanium electrodes by reactive magnetron sputtering in the pulsed direct current mode. The films exhibited all a columnar microstructure and a c-axis texture. The built-in stress and the piezoelectric properties of these films were studied as a function of both the processing conditions and the electrode material. Stress was found to be very much dependent on the growth conditions, and values ranging from strong compression to high tension were observed. The piezoelectric d 33,f coefficient was shown to rely on substrate quality and ionic bombardment: The nucleation surface must be stable with regard to the nitrogen plasma and present a hexagonal symmetry and, on the other hand, enough energy must be delivered to the growing film through ionic bombardment. [copyright] 2001 American Institute of Physics

  6. Bonding structure and morphology of chromium oxide films grown by pulsed-DC reactive magnetron sputter deposition

    Energy Technology Data Exchange (ETDEWEB)

    Gago, R., E-mail: rgago@icmm.csic.es [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas, E-28049 Madrid (Spain); Vinnichenko, M. [Fraunhofer-Institut für Keramische Technologien und Systeme IKTS, D-01277 Dresden (Germany); Hübner, R. [Helmholtz-Zentrum Dresden – Rossendorf, Institute of Ion Beam Physics and Materials Research, Bautzner Landstraße 400, 01328 Dresden (Germany); Redondo-Cubero, A. [Departamento de Física Aplicada and Centro de Microanálisis de Materiales, Universidad Autónoma de Madrid, E-28049 Madrid (Spain)

    2016-07-05

    Chromium oxide (CrO{sub x}) thin films were grown by pulsed-DC reactive magnetron sputter deposition in an Ar/O{sub 2} discharge as a function of the O{sub 2} fraction in the gas mixture (ƒ) and for substrate temperatures, T{sub s}, up to 450 °C. The samples were analysed by Rutherford backscattering spectrometry (RBS), spectroscopic ellipsometry (SE), atomic force microscopy (AFM), scanning (SEM) and transmission (TEM) electron microscopy, X-ray diffraction (XRD), and X-ray absorption near-edge structure (XANES). On unheated substrates, by increasing ƒ the growth rate is higher and the O/Cr ratio (x) rises from ∼2 up to ∼2.5. Inversely, by increasing T{sub s} the atomic incorporation rate drops and x falls to ∼1.8. XRD shows that samples grown on unheated substrates are amorphous and that nanocrystalline Cr{sub 2}O{sub 3} (x = 1.5) is formed by increasing T{sub s}. In amorphous CrO{sub x}, XANES reveals the presence of multiple Cr environments that indicate the growth of mixed-valence oxides, with progressive promotion of hexavalent states with ƒ. XANES data also confirms the formation of single-phase nanocrystalline Cr{sub 2}O{sub 3} at elevated T{sub s}. These structural changes also reflect on the optical and morphological properties of the films. - Highlights: • XANES of CrO{sub x} thin films grown by pulsed-DC reactive magnetron sputtering. • Identification of mixed-valence amorphous CrO{sub x} oxides on unheated substrates. • Promotion of amorphous chromic acid (Cr{sup VI}) by increasing O{sub 2} partial pressure. • Production of single-phase Cr{sub 2}O{sub 3} films by increasing substrate temperature. • Correlation of bonding structure with morphological and optical properties.

  7. Organic/hybrid thin films deposited by matrix-assisted pulsed laser evaporation (MAPLE)

    Science.gov (United States)

    Stiff-Roberts, Adrienne D.; Ge, Wangyao

    2017-12-01

    Some of the most exciting materials research in the 21st century attempts to resolve the challenge of simulating, synthesizing, and characterizing new materials with unique properties designed from first principles. Achievements in such development for organic and organic-inorganic hybrid materials make them important options for electronic and/or photonic devices because they can impart multi-functionality, flexibility, transparency, and sustainability to emerging systems, such as wearable electronics. Functional organic materials include small molecules, oligomers, and polymers, while hybrid materials include inorganic nanomaterials (such as zero-dimensional quantum dots, one-dimensional carbon nanotubes, or two-dimensional nanosheets) combined with organic matrices. A critically important step to implementing new electronic and photonic devices using such materials is the processing of thin films. While solution-based processing is the most common laboratory technique for organic and hybrid materials, vacuum-based deposition has been critical to the commercialization of organic light emitting diodes based on small molecules, for example. Therefore, it is desirable to explore vacuum-based deposition of organic and hybrid materials that include larger macromolecules, such as polymers. This review article motivates the need for physical vapor deposition of polymeric and hybrid thin films using matrix-assisted pulsed laser evaporation (MAPLE), which is a type of pulsed laser deposition. This review describes the development of variations in the MAPLE technique, discusses the current understanding of laser-target interactions and growth mechanisms for different MAPLE variations, surveys demonstrations of MAPLE-deposited organic and hybrid materials for electronic and photonic devices, and provides a future outlook for the technique.

  8. Reactive pulsed laser deposition of Cu2ZnSnS4 thin films in H2S

    International Nuclear Information System (INIS)

    Surgina, G.D.; Zenkevich, A.V.; Sipaylo, I.P.; Nevolin, V.N.; Drube, W.; Teterin, P.E.; Minnekaev, M.N.

    2013-01-01

    Cu 2 ZnSnS 4 (CZTS) thin films have been grown by reactive pulsed laser deposition in H 2 S atmosphere, combining the alternate ablation from the metallic (Cu) and alloyed (Zn x Sn) targets at room temperature. The morphological, structural and optical properties of as grown CZTS thin films with varying compositions as well as upon annealing in N 2 atmosphere are investigated by Rutherford backscattering spectrometry, X-ray diffraction, Raman spectroscopy and optical spectrophotometry. The chemical bonding in the “bulk” of the CZTS films is elucidated via hard X-ray photoemission spectroscopy measurements. The formation of the good quality stoichiometric polycrystalline CZTS films is demonstrated upon optimization of the growth parameters. - Highlights: ► The new method of Cu 2 ZnSnS 4 (CZTS) thin films growth in H 2 S was realized. ► CZTS films were grown by pulsed laser deposition from Cu and alloyed Zn–Sn targets. ► The effect of the processing parameters on the CZTS properties was investigated. ► The chemical bonding in the “bulk” of CZTS films was studied

  9. Gas-phase mechanisms in the growth of ZrCyN1-y thin films by pulsed reactive crossed-beam laser ablation

    International Nuclear Information System (INIS)

    Spillmann, H.; Clerc, C.; Doebeli, M.; Willmott, P.R.

    2002-01-01

    Superhard zirconium carbonitride films have been grown via pulsed reactive crossed-beam laser ablation (PRCLA) using zirconium metal and a nitrogen- and carbon-containing gas pulse mixture. The control of stoichiometry was much simplified by using the thermally stable gas-phase species N 2 and CH 4 . The gas-phase processes are investigated using quadrupole mass spectroscopy and optical emission spectroscopy. The excitation of the ablation plume depends intimately on the collision partner of the gas pulse, in particular on its density of states and the probability of energy transfer to internal degrees of freedom

  10. The influence of wavelength, temporal sequencing, and pulse duration on resonant infrared matrix-assisted laser processing of polymer films

    Science.gov (United States)

    O'Malley, S. M.; Schoeffling, Jonathan; Jimenez, Richard; Zinderman, Brian; Yi, SunYong; Bubb, D. M.

    2014-06-01

    We have carried out a systematic investigation of laser ablation plume interactions in resonant infrared matrix-assisted pulsed laser evaporation. The laser source utilized in this study was a mid-infrared OPO capable of dual sequential ns pulses with adjustable delay ranging from 1 to 100 μs. This unique capability enabled us both to probe the ablation plume with a second laser pulse, and to effectively double the laser fluence. The primary ablation target used for this study consisted of poly(methyl methacrylate) dissolved in a binary mixture of methanol and toluene. Both the critical thermodynamic and optical properties of the binary mixture were determined and used to interpret our results. We found that deposition rates associated with single pulse irradiation tracks with the optical absorption coefficient in the spectral range from 2,700 to 3,800 nm. In the case of dual sequential pulses, discrepancies in this trend have been linked to the rate of change in the optical absorption coefficient with temperature. The influence of fluence on deposition rate was found to follow a sigmoidal dependence. Surface roughness was observed to have a diametrically opposed trend with pulse delay depending on whether the OH or CH vibrational mode was excited. In the case of CH excitation, we suggest that the rougher films are due to the absorbance of the second pulse by droplets within the plume containing residual solvent which leads to the formation of molecular balloons and hence irregularly shaped features on the substrate.

  11. Growth and characterization of nitrogen-doped TiO2 thin films prepared by reactive pulsed laser deposition

    International Nuclear Information System (INIS)

    Sauthier, G.; Ferrer, F.J.; Figueras, A.; Gyoergy, E.

    2010-01-01

    Nitrogen-doped titanium dioxide (TiO 2 ) thin films were grown on (001) SiO 2 substrates by reactive pulsed laser deposition. A KrF* excimer laser source (λ = 248 nm, τ FWHM ≅ 10 ns, ν = 10 Hz) was used for the irradiations of pressed powder targets composed by both anatase and rutile phase TiO 2 . The experiments were performed in a controlled reactive atmosphere consisting of oxygen or mixtures of oxygen and nitrogen gases. The obtained thin film crystal structure was investigated by X-ray diffraction, while their chemical composition as well as chemical bonding states between the elements were studied by X-ray photoelectron spectroscopy. An interrelation was found between nitrogen concentration, crystalline structure, bonding states between the elements, and the formation of titanium oxinitride compounds. Moreover, as a result of the nitrogen incorporation in the films a continuous red-shift of the optical absorption edge accompanied by absorption in the visible spectral range between 400 and 500 nm wavelength was observed.

  12. Experimental subcritical reactivity determinations employing APSD measurements with pulse mode detectors in the IPEN/MB-01 reactor

    International Nuclear Information System (INIS)

    Santos, Adimir dos; Lee, Seung Min; Diniz, Ricardo; Jerez, Rogerio

    2011-01-01

    This work aims to determine experimentally the subcritical reactivity levels of several configurations of the IPEN/MB-01 reactor in an approach based on the subcritical kinetic model developed by Gandini and Salvatores. The procedure employs the measurements of the APSD (Auto Power Spectral Density) using pulse mode detectors. The proposed approach is based only on measured quantities such as counting rates and the parameters arising from the least square approach of the APSD. Other difficult quantity such as detector efficiencies is not needed in the method. Several measurements of APSD were performed in varying degrees of sub-criticality (up to around -7000 pcm). The APSD data were least-square fitted to get the prompt decay mode (α). Beside the startup source, an external neutron sources of Am-Be was installed near the core in order to improve neutron count statistics. The final experimental results are of very good quality. The experiment shows clearly that the classical one point kinetic theory cannot describe the measured reactivity. MCNP K eff results were compared to the corresponding experimental results. The agreement was fairly good. (author)

  13. A novel water-assisted pulsed light processing for decontamination of blueberries.

    Science.gov (United States)

    Huang, Yaoxin; Chen, Haiqiang

    2014-06-01

    Sample heating and shadowing effect have limited the application of pulsed light (PL) technology for decontamination of fresh produce. In this study, a novel setup using water-assisted PL processing was developed to overcome these limitations. Blueberries inoculated with Escherichia coli O157:H7 or Salmonella were either treated with PL directly (dry PL treatment) or immersed in agitated water during the PL treatment (wet PL treatment) for 5-60 s. Although both pathogens were effectively inactivated by the dry PL treatments, the appearance of the blueberries was adversely affected and a maximum temperature of 64.8 °C on the blueberry surface was recorded. On the other hand, the visual appearance of blueberries remained unchanged after wet PL treatments and sample heating was significantly reduced. The wet PL treatments were more effective than chlorine washing on inactivating both pathogens. After a 60-s wet PL treatment, the populations of E. coli O157:H7 inoculated on calyx and skin of blueberries were reduced by 3.0 and >5.8 log CFU/g, respectively. Salmonella on blueberry calyx and skin was reduced by 3.6 and >5.9 log CFU/g, respectively. No viable bacterial cells were recovered from the water used in the wet PL treatments, demonstrating that this setup could prevent the risk of cross-contamination during fresh produce washing. Our results suggest that this new water-assisted PL treatment could be a potential non-chemical alternative (residue free) to chlorine washing since it is both more effective and environmentally friendly than chlorine washing. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. Ion-Assisted Pulsed Laser Deposition of amorphous tetrahedral-coordinated carbon films

    Science.gov (United States)

    Friedmann, T. A.; Tallant, D. R.; Sullivan, J. P.; Siegal, M. P.; Simpson, R. L.

    1994-04-01

    A parametric study has been performed of amorphous tetrahedral carbon (a-tC) films produced by ion-assisted pulsed laser deposition (IAPLD). The ion voltage, current density, and feed gas composition (nitrogen in argon) have been varied. The resultant films were characterized by thickness, residual stress, Raman spectroscopy, and electrical resistivity. The Raman spectra have been fit to two gaussian peaks, the so called graphitic (G) peak and the disorder (D) peak. It has been found that the magnitude of the D peak and the residual compressive stress are inversely correlated. At low beam voltages and currents, the magnitude of the D peak is low, increasing as the ion beam voltage and current are raised. The ion beam voltage has the most dramatic effect on the magnitude of the D peak. At low voltages (200-500 V) the magnitude of the D peak is greater for ion beams with high percentages of nitrogen possibly indicative of C-N bonding in the films. At higher voltages (500-1500 V) the D peak intensity is less sensitive to the nitrogen content of the beam.

  15. Deposition of Methylammonium Lead Triiodide by Resonant Infrared Matrix-Assisted Pulsed Laser Evaporation

    Science.gov (United States)

    Barraza, E. Tomas; Dunlap-Shohl, Wiley A.; Mitzi, David B.; Stiff-Roberts, Adrienne D.

    2018-02-01

    Resonant infrared matrix-assisted pulsed laser evaporation (RIR-MAPLE) was used to deposit the metal-halide perovskite (MHP) CH3NH3PbI3 (methylammonium lead triiodide, or MAPbI), creating phase-pure films. Given the moisture sensitivity of these crystalline, multi-component organic-inorganic hybrid materials, deposition of MAPbI by RIR-MAPLE required a departure from the use of water-based emulsions as deposition targets. Different chemistries were explored to create targets that properly dissolved MAPbI components, were stable under vacuum conditions, and enabled resonant laser energy absorption. Secondary phases and solvent contamination in the resulting films were studied through Fourier transform infrared (FTIR) absorbance and x-ray diffraction (XRD) measurements, suggesting that lingering excess methylammonium iodide (MAI) and low-vapor pressure solvents can distort the microstructure, creating crystalline and amorphous non-perovskite phases. Thermal annealing of films deposited by RIR-MAPLE allowed for excess solvent to be evaporated from films without degrading the MAPbI structure. Further, it was demonstrated that RIR-MAPLE does not require excess MAI to create stoichiometric films with optoelectronic properties, crystal structure, and film morphology comparable to films created using more established spin-coating methods for processing MHPs. This work marks the first time a MAPLE-related technique was used to deposit MHPs.

  16. Phase transition and thermal expansion studies of alumina thin films prepared by reactive pulsed laser deposition.

    Science.gov (United States)

    Balakrishnan, G; Thirumurugesan, R; Mohandas, E; Sastikumar, D; Kuppusami, P; Songl, J I

    2014-10-01

    Aluminium oxide (Al2O3) thin films were deposited on Si (100) substrates at an optimized oxygen partial pressure of 3 x 10(-3) mbar at room temperature by pulsed laser deposition (PLD). The films were characterized by high temperature X-ray diffraction (HTXRD), field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). The HTXRD pattern showed the cubic y-Al2O3 phase in the temperature range 300-973 K. At temperatures ≥ 1073 K, the δ and θ-phases of Al2O3 were observed. The mean linear thermal expansion coefficient and volume thermal expansion coefficient of γ-Al2O3 was found to be 12.66 x 10(-6) K(-1) and 38.87 x 10(-6) K(-1) in the temperature range 300 K-1073 K. The field emission scanning electron microscopy revealed a smooth and structureless morphology of the films deposited on Si (100). The atomic force microscopy study indicated the increased crystallinity and surface roughness of the films after annealing at high temperature.

  17. TiCN thin films grown by reactive crossed beam pulsed laser deposition

    Science.gov (United States)

    Escobar-Alarcón, L.; Camps, E.; Romero, S.; Muhl, S.; Camps, I.; Haro-Poniatowski, E.

    2010-12-01

    In this work, we used a crossed plasma configuration where the ablation of two different targets in a reactive atmosphere was performed to prepare nanocrystalline thin films of ternary compounds. In order to assess this alternative deposition configuration, titanium carbonitride (TiCN) thin films were deposited. Two crossed plasmas were produced by simultaneously ablating titanium and graphite targets in an Ar/N2 atmosphere. Films were deposited at room temperature onto Si (100) and AISI 4140 steel substrates whilst keeping the ablation conditions of the Ti target constant. By varying the laser fluence on the carbon target it was possible to study the effect of the carbon plasma on the characteristics of the deposited TiCN films. The structure and composition of the films were analyzed by X-ray Diffraction, Raman Spectroscopy and non-Rutherford Backscattering Spectroscopy. The hardness and elastic modulus of the films was also measured by nanoindentation. In general, the experimental results showed that the TiCN thin films were highly oriented in the (111) crystallographic direction with crystallite sizes as small as 6.0 nm. It was found that the hardness increased as the laser fluence was increased, reaching a maximum value of about 33 GPa and an elastic modulus of 244 GPa. With the proposed configuration, the carbon content could be easily varied from 42 to 5 at.% by changing the laser fluence on the carbon target.

  18. Inverse correlation between reactive oxygen species in unwashed semen and sperm motion parameters as measured by a computer-assisted semen analyzer.

    Science.gov (United States)

    Takeshima, Teppei; Yumura, Yasushi; Yasuda, Kengo; Sanjo, Hiroyuki; Kuroda, Shinnosuke; Yamanaka, Hiroyuki; Iwasaki, Akira

    2017-01-01

    This study investigated the correlation between sperm motion parameters obtained by a computer-assisted semen analyzer and levels of reactive oxygen species in unwashed semen. In total, 847 patients, except for azoospermic patients were investigated. At the time of each patient's first consultation, semen parameters were measured using SMAS™ or CellSoft 3000™, and production of reactive oxygen species was measured using a computer-driven LKB Wallac Luminometer 1251 Analyzer. The patients were divided into two groups: reactive oxygen species - positive and negative. The semen parameters within each group were measured using one of the two computer-assisted semen analyzer systems and then compared. Correlations between reactive oxygen species levels and sperm motion parameters in semen from the reactive oxygen species - positive group were also investigated. Reactive oxygen species were detected in semen samples of 282 cases (33.3%). Sperm concentration (P semen damage sperm concentration, motility, and other sperm motion parameters.

  19. A global plasma model for reactive deposition of compound films by modulated pulsed power magnetron sputtering discharges

    Science.gov (United States)

    Zheng, B. C.; Wu, Z. L.; Wu, B.; Li, Y. G.; Lei, M. K.

    2017-05-01

    A spatially averaged, time-dependent global plasma model has been developed to describe the reactive deposition of a TiAlSiN thin film by modulated pulsed power magnetron sputtering (MPPMS) discharges in Ar/N2 mixture gas, based on the particle balance and the energy balance in the ionization region, and considering the formation and erosion of the compound at the target surface. The modeling results show that, with increasing the N2 partial pressure from 0% to 40% at a constant working pressure of 0.3 Pa, the electron temperature during the strongly ionized period increases from 4 to 7 eV and the effective power transfer coefficient, which represents the power fraction that effectively heats the electrons and maintains the discharge, increases from about 4% to 7%; with increasing the working pressure from 0.1 to 0.7 Pa at a constant N2 partial pressure of 25%, the electron temperature decreases from 10 to 4 eV and the effective power transfer coefficient decreases from 8% to 5%. Using the modeled plasma parameters to evaluate the kinetic energy of arriving ions, the ion-to-neutral flux ratio of deposited species, and the substrate heating, the variations of process parameters that increase these values lead to an enhanced adatom mobility at the target surface and an increased input energy to the substrate, corresponding to the experimental observation of surface roughness reduction, the microstructure transition from the columnar structure to the dense featureless structure, and the enhancement of phase separation. At higher N2 partial pressure or lower working pressure, the modeling results demonstrate an increase in electron temperature, which shifts the discharge balance of Ti species from Ti+ to Ti2+ and results in a higher return fraction of Ti species, corresponding to the higher Al/Ti ratio of deposited films at these conditions. The modeling results are well correlated with the experimental observation of the composition variation and the microstructure

  20. Single attosecond pulse from terahertz-assisted high-order harmonic generation

    Science.gov (United States)

    Balogh, Emeric; Kovacs, Katalin; Dombi, Peter; Fulop, Jozsef A.; Farkas, Gyozo; Hebling, Janos; Tosa, Valer; Varju, Katalin

    2011-08-01

    High-order harmonic generation by few-cycle 800 nm laser pulses in neon gas in the presence of a strong terahertz (THz) field is investigated numerically with propagation effects taken into account. Our calculations show that the combination of THz fields with up to 12 fs laser pulses can be an effective gating technique to generate single attosecond pulses. We show that in the presence of the strong THz field only a single attosecond burst can be phase matched, whereas radiation emitted during other half cycles disappears during propagation. The cutoff is extended and a wide supercontinuum appears in the near-field spectra, extending the available spectral width for isolated attosecond pulse generation from 23 to 93 eV. We demonstrate that phase-matching effects are responsible for the generation of isolated attosecond pulses, even in conditions when single-atom response yields an attosecond pulse train.

  1. Single attosecond pulse from terahertz-assisted high-order harmonic generation

    International Nuclear Information System (INIS)

    Balogh, Emeric; Kovacs, Katalin; Dombi, Peter; Farkas, Gyozo; Fulop, Jozsef A.; Hebling, Janos; Tosa, Valer; Varju, Katalin

    2011-01-01

    High-order harmonic generation by few-cycle 800 nm laser pulses in neon gas in the presence of a strong terahertz (THz) field is investigated numerically with propagation effects taken into account. Our calculations show that the combination of THz fields with up to 12 fs laser pulses can be an effective gating technique to generate single attosecond pulses. We show that in the presence of the strong THz field only a single attosecond burst can be phase matched, whereas radiation emitted during other half cycles disappears during propagation. The cutoff is extended and a wide supercontinuum appears in the near-field spectra, extending the available spectral width for isolated attosecond pulse generation from 23 to 93 eV. We demonstrate that phase-matching effects are responsible for the generation of isolated attosecond pulses, even in conditions when single-atom response yields an attosecond pulse train.

  2. Single attosecond pulse from terahertz-assisted high-order harmonic generation

    Energy Technology Data Exchange (ETDEWEB)

    Balogh, Emeric [Department of Optics and Quantum Electronics, University of Szeged, H-6701 Szeged (Hungary); Kovacs, Katalin [Department of Optics and Quantum Electronics, University of Szeged, H-6701 Szeged (Hungary); National Institute for R and D of Isotopic and Molecular Technologies, RO-400293 Cluj-Napoca (Romania); Dombi, Peter; Farkas, Gyozo [Research Institute for Solid State Physics and Optics, H-1525 Budapest (Hungary); Fulop, Jozsef A.; Hebling, Janos [Department of Experimental Physics, University of Pecs, H-7624 Pecs (Hungary); Tosa, Valer [National Institute for R and D of Isotopic and Molecular Technologies, RO-400293 Cluj-Napoca (Romania); Varju, Katalin [HAS Research Group on Laser Physics, University of Szeged, H-6701 Szeged (Hungary)

    2011-08-15

    High-order harmonic generation by few-cycle 800 nm laser pulses in neon gas in the presence of a strong terahertz (THz) field is investigated numerically with propagation effects taken into account. Our calculations show that the combination of THz fields with up to 12 fs laser pulses can be an effective gating technique to generate single attosecond pulses. We show that in the presence of the strong THz field only a single attosecond burst can be phase matched, whereas radiation emitted during other half cycles disappears during propagation. The cutoff is extended and a wide supercontinuum appears in the near-field spectra, extending the available spectral width for isolated attosecond pulse generation from 23 to 93 eV. We demonstrate that phase-matching effects are responsible for the generation of isolated attosecond pulses, even in conditions when single-atom response yields an attosecond pulse train.

  3. Polarity inversion of AlN film grown on nitrided a-plane sapphire substrate with pulsed DC reactive sputtering

    Directory of Open Access Journals (Sweden)

    Marsetio Noorprajuda

    2018-04-01

    Full Text Available The effect of oxygen partial pressure (PO2 on polarity and crystalline quality of AlN films grown on nitrided a-plane sapphire substrates by pulsed direct current (DC reactive sputtering was investigated as a fundamental study. The polarity inversion of AlN from nitrogen (−c-polarity to aluminum (+c-polarity occurred during growth at a high PO2 of 9.4×103 Pa owing to Al-O octahedral formation at the interface of nitrided layer and AlN sputtered film which reset the polarity of AlN. The top part of the 1300 nm-thick AlN film sputtered at the high PO2 was polycrystallized. The crystalline quality was improved owing to the high kinetic energy of Al sputtered atom in the sputtering phenomena. Thinner AlN films were also fabricated at the high PO2 to eliminate the polycrystallization. For the 200 nm-thick AlN film sputtered at the high PO2, the full width at half-maximum values of the AlN (0002 and (10−12 X-ray diffraction rocking curves were 47 and 637 arcsec, respectively.

  4. Amplification of pressure waves in laser-assisted endodontics with synchronized delivery of Er:YAG laser pulses.

    Science.gov (United States)

    Lukač, Nejc; Jezeršek, Matija

    2018-05-01

    When attempting to clean surfaces of dental root canals with laser-induced cavitation bubbles, the resulting cavitation oscillations are significantly prolonged due to friction on the cavity walls and other factors. Consequently, the collapses are less intense and the shock waves that are usually emitted following a bubble's collapse are diminished or not present at all. A new technique of synchronized laser-pulse delivery intended to enhance the emission of shock waves from collapsed bubbles in fluid-filled endodontic canals is reported. A laser beam deflection probe, a high-speed camera, and shadow photography were used to characterize the induced photoacoustic phenomena during synchronized delivery of Er:YAG laser pulses in a confined volume of water. A shock wave enhancing technique was employed which consists of delivering a second laser pulse at a delay with regard to the first cavitation bubble-forming laser pulse. Influence of the delay between the first and second laser pulses on the generation of pressure and shock waves during the first bubble's collapse was measured for different laser pulse energies and cavity volumes. Results show that the optimal delay between the two laser pulses is strongly correlated with the cavitation bubble's oscillation period. Under optimal synchronization conditions, the growth of the second cavitation bubble was observed to accelerate the collapse of the first cavitation bubble, leading to a violent collapse, during which shock waves are emitted. Additionally, shock waves created by the accelerated collapse of the primary cavitation bubble and as well of the accompanying smaller secondary bubbles near the cavity walls were observed. The reported phenomena may have applications in improved laser cleaning of surfaces during laser-assisted dental root canal treatments.

  5. Low-threshold ablation of enamel and dentin using Nd:YAG laser assisted with chromophore with different pulse shapes

    Science.gov (United States)

    Bonora, Stefano; Benazzato, Paolo; Stefani, Alessandro; Villoresi, Paolo

    2004-05-01

    Neodimium laser treatment has several drawbacks when used in the hard tissue cutting, because of the low absorption of the dental tissues at its wavelength. This investigation proved that the Nd:YAG radiation is a powerful ablation tool if it is used with the dye assisted method. Several in vitro tests on enamel and dentin were accomplished changing some laser parameters to have different pulse shapes and durations from 125μs up to 1.4ms. The importance of short time high power peaks, typical of crystal lasers, in the ablation process was investigated. The pulse shapes were analyzed by their intensity in space and time profiles. A first set of results found the optimum dye concentration be used in all the following tests. Furthermore the ablation threshold for this technique was found for each different pulse shapes and durations. A low energy ablation method was found to avoid temperature increase and surface cracks formation. In vitro temperature analysis was reported comparing the differences between no dye application laser treatment and with a dye spray applied. A strong reduction of the temperature increase was found in the dye assisted method. A discussion on the general findings and their possible clinical applications is presented.

  6. Composition, structure and properties of SiN x films fabricated by pulsed reactive closed-field unbalanced magnetron sputtering

    International Nuclear Information System (INIS)

    Yao, Zh.Q.; Yang, P.; Huang, N.; Sun, H.; Wan, G.J.; Leng, Y.X.; Chen, J.Y.

    2005-01-01

    Silicon nitride (SiN x ) thin films are of special interest in both scientific research and industrial applications due to their remarkable properties such as high thermal stability, chemical inertness, high hardness and good dielectric properties. In this work, SiN x films were fabricated by pulsed reactive closed-field unbalanced magnetron sputtering of high purity single crystal silicon targets in an Ar-N 2 mixture. The effect of N 2 partial pressure on the film composition, chemical bonding configurations, surface morphology, surface free energy, optical and mechanical properties were investigated. We showed that with increased N 2 partial pressure, the N to Si ratio (N/Si) in the film increased and N atoms are preferentially incorporated in the NSi 3 stoichiometric configuration. It leads the Si-N network a tendency to chemical order. Films deposited at a high N 2 fraction were consistently N-rich. The film surface transformed from a loose granular structure with microporosity to a homogeneous, continuous, smooth and dense structure. A progressive densification of the film microstructure occurs as the N 2 fraction is increased. The reduced surface roughness and the increased N incorporation in the film give rise to the increased contact angle with double-distilled water from 24 o to 49.6 o . To some extent, the SiN x films deposited by pulsed magnetron sputtering are hydrophilic in nature. The as-deposited SiN x films exhibit good optical transparency in the visible region and the optical band gap E opt can be varied from 1.68 eV for a-Si to 3.62 eV for SiN x films, depending on the synthesis parameters. With the increase of the N/Si atomic ratio, wear resistance of the SiN x films was improved, a consequence of increased hardness and elastic modulus. The SiN x films have lower friction coefficient and better wear resistance than 316L stainless steel under dry sliding friction, where the SiN x films experienced only fatigue wear

  7. Determination of reactivity of multiplying systems filled with spherical HTGR-fuel elements using kinetic methods with regard to the pulsed-neutron method

    International Nuclear Information System (INIS)

    Drueke, V.

    1978-06-01

    At three critical or subcritical facilities - two of them filled with spherical HTGR-fuel elements - the reactivity is determined using kinetic methods. Besides the inverskinetic method the applicability of the pulsed-neutron method is investigated. The experimental results using the pulsed-neutron method are compared partly with the inverskinetic method and partly with diffusion-calculations. It is shown, that in the HTGR the space dependence of the reactivity in radial direction is not remarkable in spite of the 'kinetic distortion'; on the contrary in axial direction - the direction of the external neutron source - space dependent reactivity worths are measured. The results of the pulsed-neutron methods of Sjoestrand and Simmons-King are rather good applicable in all configurations. For the method of Sjoestrand it is necessary to select the detector positions, whereas for Simmons-King the calculated life-time determines the results. Therefore it is proposed to compare calculated and measured decay constants of the prompt neutron field in future. (orig.) [de

  8. Nanoscale multilayered and porous carbide interphases prepared by pressure-pulsed reactive chemical vapor deposition for ceramic matrix composites

    International Nuclear Information System (INIS)

    Jacques, S.; Jouanny, I.; Ledain, O.; Maillé, L.; Weisbecker, P.

    2013-01-01

    In Ceramic Matrix Composites (CMCs) reinforced by continuous fibers, a good toughness is achieved by adding a thin film called “interphase” between the fiber and the brittle matrix, which acts as a mechanical fuse by deflecting the matrix cracks. Pyrocarbon (PyC), with or without carbide sub-layers, is typically the material of choice to fulfill this role. The aim of this work was to study PyC-free nanoscale multilayered carbide coatings as interphases for CMCs. Nanoscale multilayered (SiC–TiC) n interphases were deposited by pressure-Pulsed Chemical Vapor Deposition (P-CVD) on single filament Hi-Nicalon fibers and embedded in a SiC matrix sheath. The thicknesses of the carbide interphase sub-layers could be made as low as a few nanometers as evidenced by scanning and transmission electron microscopy. By using the P-ReactiveCVD method (P-RCVD), in which the TiC growth involves consumption of SiC, it was not only possible to obtain multilayered (SiC–TiC) n films but also TiC films with a porous multilayered microstructure as a result of the Kirkendall effect. The porosity in the TiC sequences was found to be enhanced when some PyC was added to SiC prior to total RCVD consumption. Because the porosity volume fraction was still not high enough, the role of mechanical fuse of the interphases could not be evidenced from the tensile curves, which remained fully linear even when chemical attack of the fiber surface was avoided.

  9. Nanoscale multilayered and porous carbide interphases prepared by pressure-pulsed reactive chemical vapor deposition for ceramic matrix composites

    Science.gov (United States)

    Jacques, S.; Jouanny, I.; Ledain, O.; Maillé, L.; Weisbecker, P.

    2013-06-01

    In Ceramic Matrix Composites (CMCs) reinforced by continuous fibers, a good toughness is achieved by adding a thin film called "interphase" between the fiber and the brittle matrix, which acts as a mechanical fuse by deflecting the matrix cracks. Pyrocarbon (PyC), with or without carbide sub-layers, is typically the material of choice to fulfill this role. The aim of this work was to study PyC-free nanoscale multilayered carbide coatings as interphases for CMCs. Nanoscale multilayered (SiC-TiC)n interphases were deposited by pressure-Pulsed Chemical Vapor Deposition (P-CVD) on single filament Hi-Nicalon fibers and embedded in a SiC matrix sheath. The thicknesses of the carbide interphase sub-layers could be made as low as a few nanometers as evidenced by scanning and transmission electron microscopy. By using the P-ReactiveCVD method (P-RCVD), in which the TiC growth involves consumption of SiC, it was not only possible to obtain multilayered (SiC-TiC)n films but also TiC films with a porous multilayered microstructure as a result of the Kirkendall effect. The porosity in the TiC sequences was found to be enhanced when some PyC was added to SiC prior to total RCVD consumption. Because the porosity volume fraction was still not high enough, the role of mechanical fuse of the interphases could not be evidenced from the tensile curves, which remained fully linear even when chemical attack of the fiber surface was avoided.

  10. High C reactive protein associated with increased pulse wave velocity among urban men with metabolic syndrome in Malaysia.

    Science.gov (United States)

    Aminuddin, Amilia; Zakaria, Zaiton; Fuad, Ahmad F; Kamsiah, Jaarin; Othman, Faizah; Das, Srijit; Kamisah, Yusof; Qodriyah, Haji S; Jubri, Zakiah; Nordin, Nor Anita M; Ngah, Wan Z

    2013-03-01

    To determine the association between carotid femoral pulse wave velocity (PWVCF); augmentation index (AI); and high-sensitivity C reactive protein (hs-CRP) with metabolic syndrome (MetS), and to determine the influence of ethnicity on PWVCF and AI, and the association between high hs-CRP and increased PWV, and AI in MetS. A cross-sectional study was conducted at Universiti Kebangsaan Malaysia Medical Center, Kuala Lumpur, Malaysia from September 2009 to September 2011. Three hundred and eighty men (Chinese and Malays) were recruited from the study. The PWVCF and AI were measured by Vicorder (SMT Medical, Wuerzburg, Germany). The hs-CRP level was also determined. We defined MetS using the International Diabetes Federation (IDF) and harmonized criteria. Malays had higher AI compared to the Malaysian Chinese. Patients with MetS had higher PWVCF (IDF criteria: 8.5 [8.3-8.7] versus 8.2 [8.0-8.4] m/s, p=0.03; harmonized criteria: 8.5 [8.4-8.7] versus 8.2 [8.0-8.4] m/s, p=0.007) and hs-CRP (IDF criteria: 0.9+/-2.0 versus 0.4+/-1.1 mg/L, p=0.0007; harmonized criteria: 0.8+/-1.9 versus 0.4+/-1.1 mg/L, p=0.002) compared to non-MetS. In subjects with MetS, those with high hs-CRP (>3 mg/L) had higher PWVCF. Augmentation index values were significantly higher in Malays compared with Malaysian Chinese. Metabolic syndrome was associated with increased PWVCF and hs-CRP. Patients with MetS and high hs-CRP were associated with higher PWVCF. The measurement of hs-CRP reflects the degree of subclinical vascular damage in MetS.

  11. Design challenges for matrix assisted pulsed laser evaporation and infrared resonant laser evaporation equipment

    Science.gov (United States)

    Greer, James A.

    2011-11-01

    Since the development of the Matrix Assisted Pulsed Laser Evaporation (MAPLE) process by the Naval Research Laboratory (NRL) in the late 1990s, MAPLE has become an active area of research for the deposition of a variety of polymer, biological, and organic thin films. As is often the case with advancements in thin-film deposition techniques new technology sometimes evolves by making minor or major adjustments to existing deposition process equipment and techniques. This is usually the quickest and least expensive way to try out new ideas and to "push the envelope" in order to obtain new and unique scientific results as quickly as possible. This process of "tweaking" current equipment usually works to some degree, but once the new process is further refined overall designs for a new deposition tool based on the critical attributes of the new process typically help capitalize more fully on the all the salient features of the new and improved process. This certainly has been true for the MAPLE process. In fact the first MAPLE experiments the polymer/solvent matrix was mixed and poured into a copper holder held at LN2 temperature on a laboratory counter top. The holder was then quickly placed onto a LN2 cooled reservoir in a vacuum deposition chamber and placed in a vertical position on a LN2 cooled stage and pumped down as quickly as possible. If the sample was not placed into the chamber quickly enough the frozen matrix would melt and drip into the bottom of the chamber onto the chambers main gate valve making a bit of a mess. However, skilled and motivated scientists usually worked quickly enough to make this process work most of the time. The initial results from these experiments were encouraging and led to several publications which sparked considerable interest in this newly developed technique Clearly this approach provided the vision that MAPLE was a viable deposition process, but the equipment was not optimal for conducting MAPLE experiments on a regular basis

  12. Long-pulsed dye laser versus long-pulsed dye laser-assisted photodynamic therapy for acne vulgaris: A randomized controlled trial

    DEFF Research Database (Denmark)

    Haedersdal, M.; Togsverd, K.; Wiegell, S.R.

    2008-01-01

    Background: Long-pulsed dye laser (LPDL)-assisted photodynamic therapy has been suggested to be superior to laser alone for acne vulgaris but no evidence is available. Objective: To evaluate the efficacy and safety of LPDL alone versus LPDL in photodynamic therapy with methylaminolevulinic acid...... (MAL-LPDL) for acne vulgaris. Methods: Fifteen patients received a series of 3 full-face LPDL treatments and half-face prelaser MAL treatments; the latter being randomly assigned to the left or right side. Results: Inflammatory lesions were reduced more on MAL-LPDL-treated than on LPDL-treated sides...... to draw conclusions about the efficacy of the LPDL, only about the efficacy of MAL-LPDL compared with LPDL alone. Conclusions: MAL-LPDL is slightly superior to LPDL for the treatment of inflammatory acne Udgivelsesdato: 2008/3...

  13. Photoluminescence of Eu-doped LiYF4 thin films grown by pulsed laser deposition and matrix-assisted pulsed laser evaporation

    International Nuclear Information System (INIS)

    Stokker-Cheregi, F; Matei, A; Dinescu, M; Secu, C E; Secu, M

    2014-01-01

    Matrix-assisted pulsed laser evaporation (MAPLE) has been investigated as an alternative to the pulsed laser deposition (PLD) technique for Eu 3+ -doped crystalline LiYF 4 thin-films deposition. MAPLE assumes laser ablation of a frozen target made of the material of interest diluted in a solvent, rather than that of a bulk target, of either pressed powder or single crystal, used in the case of PLD. Our approach stems from the assumption that laser ablation of a frozen dilute target would result in thin films with improved morphology, as compared to PLD. Indeed, we find that roughness values of samples obtained by the MAPLE technique are four times lower than in the case of PLD. A lower transmittance was noticed for PLD obtained layers with respect to those grown by MAPLE due to strong scattering of light by the morphological defects. Photoluminescence spectra are showing characteristic Eu 3+ -ion luminescence bands at 578, 591, 612, 650 and 698 nm ( 5 D 0  →  7 F J ); crystal field splitting of the bands indicates dopant ions incorporation in the host material during transfer by either PLD or MAPLE. (paper)

  14. Uniform thin films of TiO2 nanoparticles deposited by matrix-assisted pulsed laser evaporation

    International Nuclear Information System (INIS)

    Caricato, A.P.; Manera, M.G.; Martino, M.; Rella, R.; Romano, F.; Spadavecchia, J.; Tunno, T.; Valerini, D.

    2007-01-01

    We report morphological and optical properties of a colloidal TiO 2 nanoparticle film, deposited on a quartz substrate by using the Matrix-Assisted Pulsed Laser Evaporation (MAPLE) technique. Atomic Force Microscopy demonstrated that a good uniformity of the deposition can be obtained. The presence of agglomerates with dimensions of about 1 μm in size was noticed. Form UV-vis transmission spectra, recorded in the 200-800 nm range, the optical constants and the energy gap were determined besides the film thickness. The optical constants resulted in agreement with the values reported in literature for TiO 2 nanoparticle thin films

  15. Deposition of matrix-free fullerene films with improved morphology by matrix-assisted pulsed laser evaporation (MAPLE)

    DEFF Research Database (Denmark)

    Canulescu, Stela; Schou, Jørgen; Fæster, Søren

    2013-01-01

    Thin films of C60 were deposited by matrix-assisted pulsed laser evaporation (MAPLE) from a frozen target of anisole with 0.67 wt% C60. Above a fluence of 1.5 J/cm2 the C60 films are strongly non-uniform and are resulting from transfer of matrix-droplets containing fullerenes. At low fluence...... the fullerene molecules in the films are intact, the surface morphology is substantially improved and there are no measurable traces of the matrix molecules in the film. This may indicate a regime of dominant evaporation at low fluence which merges into the MAPLE regime of liquid ejection of the host matrix...

  16. Synthesis of benzamides by microwave assisted ring opening of less reactive dimethylaminobenzylidene oxazolone

    Directory of Open Access Journals (Sweden)

    Saurabh C. Khadse

    2017-02-01

    Full Text Available This paper presents the synthesis of some benzamide compounds (B1–B10 by microwave-assisted ring opening of 4-(4-dimethylaminobenzylidene-2-phenyl-5-oxazolone (AZ4. By conventional synthesis involving heating, it was found difficult to obtain ring-opened products, probably due to poor tendency of the carbonyl carbon (C5 of AZ4 to undergo nucleophilic attack by mono/or disubstituted anilines. Microwave assisted reactions were easy to perform, have reduced the reaction time and produced good yields.

  17. Decolourisation of simulated reactive dyebath effluents by electrochemical oxidation assisted by UV light.

    Science.gov (United States)

    López-Grimau, V; Gutiérrez, M C

    2006-01-01

    This study is focused on the optimisation of the electrochemical decolourisation of textile effluents containing reactive dyes with the aim of making feasible-technically and economically-this method at industrial scale. Coloured waters were treated in continuous at low current density, to reduce the electrical consumption. Ti/PtO(x) electrodes were used to oxidize simulated dyebaths prepared with an azo/dichlorotriazine reactive dye (C.I. Reactive Orange 4). The decolourisation yield was dependent on the dyeing electrolyte (NaCl or Na(2)SO(4)). Dyeing effluents which contained from 0.5 to 20 gl(-1) of NaCl reached a high decolourisation yield, depending on the current density, immediately after the electrochemical process. These results were improved when the effluents were stored for several hours under solar light. After the electrochemical treatment the effluents were stored in a tank and exposed under different lighting conditions: UV light, solar light and darkness. The evolution of the decolourisation versus the time of storage was reported and kinetic constants were calculated. The time of storage was significantly reduced by the application of UV light. A dye mineralization study was also carried out on a concentrated dyebath. A TOC removal of 81% was obtained when high current density was applied for a prolonged treatment with recirculation. This treatment required a high electrical consumption.

  18. High fluence deposition of polyethylene glycol films at 1064 nm by matrix assisted pulsed laser evaporation (MAPLE)

    DEFF Research Database (Denmark)

    Purice, Andreea; Schou, Jørgen; Kingshott, P.

    2007-01-01

    Matrix assisted pulsed laser evaporation (MAPLE) has been applied for deposition of thin polyethylene glycol (PEG) films with infrared laser light at 1064 nm. We have irradiated frozen targets (of 1 wt.% PEG dissolved in water) and measured the deposition rate in situ with a quartz crystal 2...... microbalance. The laser fluence needed to produce PEG films turned out to be unexpectedly high with a threshold of 9 J/cm(2) and the deposition rate was much lower than that with laser light at 355 nm. Results from matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI......-TOF-MS) analysis demonstrate that the chemistry, molecular weight and polydispersity of the PEG films were identical to the starting material. Studies of the film surface with scanning electron microscopy (SEM) indicate that the Si-substrate is covered by a relatively homogenous PEG film with few bare spots. (c...

  19. Efficient and controllable thermal ablation induced by short-pulsed HIFU sequence assisted with perfluorohexane nanodroplets.

    Science.gov (United States)

    Chang, Nan; Lu, Shukuan; Qin, Dui; Xu, Tianqi; Han, Meng; Wang, Supin; Wan, Mingxi

    2018-07-01

    A HIFU sequence with extremely short pulse duration and high pulse repetition frequency can achieve thermal ablation at a low acoustic power using inertial cavitation. Because of its cavitation-dependent property, the therapeutic outcome is unreliable when the treatment zone lacks cavitation nuclei. To overcome this intrinsic limitation, we introduced perfluorocarbon nanodroplets as extra cavitation nuclei into short-pulsed HIFU-mediated thermal ablation. Two types of nanodroplets were used with perfluorohexane (PFH) as the core material coated with bovine serum albumin (BSA) or an anionic fluorosurfactant (FS) to demonstrate the feasibility of this study. The thermal ablation process was recorded by high-speed photography. The inertial cavitation activity during the ablation was revealed by sonoluminescence (SL). The high-speed photography results show that the thermal ablation volume increased by ∼643% and 596% with BSA-PFH and FS-PFH, respectively, than the short-pulsed HIFU alone at an acoustic power of 19.5 W. Using nanodroplets, much larger ablation volumes were created even at a much lower acoustic power. Meanwhile, the treatment time for ablating a desired volume significantly reduced in the presence of nanodroplets. Moreover, by adjusting the treatment time, lesion migration towards the HIFU transducer could also be avoided. The SL results show that the thermal lesion shape was significantly dependent on the inertial cavitation in this short-pulsed HIFU-mediated thermal ablation. The inertial cavitation activity became more predictable by using nanodroplets. Therefore, the introduction of PFH nanodroplets as extra cavitation nuclei made the short-pulsed HIFU thermal ablation more efficient by increasing the ablation volume and speed, and more controllable by reducing the acoustic power and preventing lesion migration. Copyright © 2018. Published by Elsevier B.V.

  20. Dipole-resonance assisted isomerization in the electronic ground state using few-cycle infrared pulses.

    Science.gov (United States)

    Skocek, Oliver; Uiberacker, Christoph; Jakubetz, Werner

    2011-06-30

    A computational investigation of HCN → HNC isomerization in the electronic ground state by one- and few-cycle infrared pulses is presented. Starting from a vibrationally pre-excited reagent state, isomerization yields of more than 50% are obtained using single one- to five-cycle pulses. The principal mechanism includes two steps of population transfer by dipole-resonance (DR), and hence, the success of the method is closely linked to the polarity of the system and, in particular, the stepwise change of the dipole moment from reactant to transition state and on to products. The yield drops massively if the diagonal dipole matrix elements are artificially set to zero. In detail, the mechanism includes DR-induced preparation of a delocalized vibrational wavepacket, which traverses the barrier region and is finally trapped in the product well by DR-dominated de-excitation. The excitation and de-excitation steps are triggered by pulse lobes of opposite field direction. As the number of optical cycles is increased, the leading field lobes prepare a vibrational superposition state by off-resonant ladder climbing, which is then subjected to the three steps of the principal isomerization mechanism. DR excitation is more efficient from a preformed vibrational wavepacket than from a molecular eigenstate. The entire process can be loosely described as Tannor-Kosloff-Rice type transfer mechanism on a single potential surface effected by a single pulse, individual field lobes assuming the roles of pump- and dump-pulses. Pre-excitation to a transient wavepacket can be enhanced by applying a separate, comparatively weak few-cycle prepulse, in which the prepulse prepares a vibrational wavepacket. The two-pulse setup corresponds to a double Tannor-Kosloff-Rice control scheme on a single potential surface.

  1. Validation of Noninvasive MOEMS-Assisted Measurement System Based on CCD Sensor for Radial Pulse Analysis

    Directory of Open Access Journals (Sweden)

    Rolanas Dauksevicius

    2013-04-01

    Full Text Available Examination of wrist radial pulse is a noninvasive diagnostic method, which occupies a very important position in Traditional Chinese Medicine. It is based on manual palpation and therefore relies largely on the practitioner’s subjective technical skills and judgment. Consequently, it lacks reliability and consistency, which limits practical applications in clinical medicine. Thus, quantifiable characterization of the wrist pulse diagnosis method is a prerequisite for its further development and widespread use. This paper reports application of a noninvasive CCD sensor-based hybrid measurement system for radial pulse signal analysis. First, artery wall deformations caused by the blood flow are calibrated with a laser triangulation displacement sensor, following by the measurement of the deformations with projection moiré method. Different input pressures and fluids of various viscosities are used in the assembled artificial blood flow system in order to test the performance of laser triangulation technique with detection sensitivity enhancement through microfabricated retroreflective optical element placed on a synthetic vascular graft. Subsequently, the applicability of double-exposure whole-field projection moiré technique for registration of blood flow pulses is considered: a computational model and representative example are provided, followed by in vitro experiment performed on a vascular graft with artificial skin atop, which validates the suitability of the technique for characterization of skin surface deformations caused by the radial pulsation.

  2. Reactivity of lignin and lignin models towards UV-assisted peroxide

    International Nuclear Information System (INIS)

    Sun, Y.P.; Wallis, A.F.A.; Nguyen, K.L.

    1997-01-01

    The comparative reactivities of a series of guaiacyl and syringyl lignin model compounds and their methylated analogues towards alkaline peroxide and UV-alkaline peroxide were investigated. The overall reaction was followed by monitoring the reduction of the substrate as a function of time, and in every case, the reaction showed pseudo-first-order kinetics. The reaction rates of most lignin models having identical sidechains with alkaline peroxide and with UV-alkaline peroxide were in the order syringyl guaiacyl 3,4,5-trimethoxyphenyl veratryl. Thus phenols react faster than their methyl ethers, and an extra ortho methoxyl group promotes the reaction. Lignin models possessing electron-donating sidechains had generally higher reaction rates than those with electron-withdrawing sidechains. The reaction rates of the series of benzoic acids were 2-4 times higher at pH 11 than at pH 5. UV-peroxide degradation of a eucalypt kraft lignin was faster than that of a pine kraft lignin, and degradation was 1.4-1.6 times faster at pH 11 than at pH 5. The data are consistent with the formation of higher amounts of reactive radicals under alkaline conditions, and aromatic rings with greater electronegativities promoting reactions with the radicals

  3. Stresses and Temperature Stability of Dense Wavelength Division Multiplexing Filters Prepared by Reactive Ion-Assisted E-Gun Evaporation

    Science.gov (United States)

    Wei, Chao-Tsang; Shieh, Han-Ping D.

    2005-10-01

    In this paper, we report the in situ measurement of the temperature stability of narrow-band-pass filters on different types of substrate, for dense wavelength division multiplexing (DWDM) filters in optical-fiber transmission systems. The DWDM filters were designed as all-dielectric Fabry-Perot filters and fabricated by reactive ion-assisted deposition. Ta2O5 and SiO2 were used as high- and low-refractive-index layers, respectively, for constructing the DWDM filters. The accuracy and stability of the coating process were evaluated for fabricating the DWDM filters for the temperature stability of the center wavelength. The center wavelength shift was determined to be greatly dependent on the coefficient of thermal expansion of the substrate on which the filter is deposited.

  4. Temperature dependence of InN film deposition by an RF plasma-assisted reactive ion beam sputtering deposition technique

    International Nuclear Information System (INIS)

    Shinoda, Hiroyuki; Mutsukura, Nobuki

    2005-01-01

    Indium nitride (InN) films were deposited on Si(100) substrates using a radiofrequency (RF) plasma-assisted reactive ion beam sputtering deposition technique at various substrate temperatures. The X-ray diffraction patterns of the InN films suggest that the InN films deposited at substrate temperatures up to 370 deg C were cubic crystalline InN; and at 500 deg C, the InN film was hexagonal crystalline InN. In a scanning electron microscope image of the InN film surface, facets of cubic single-crystalline InN grains were clearly observed on the InN film deposited at 370 deg C. The inclusion of metallic indium appeared on the InN film deposited at 500 deg C

  5. A study on matrix assisted pulsed evaporation (MAPLE) of organic materials

    DEFF Research Database (Denmark)

    Matei, Andreea; Canulescu, Stela; Constantinescu, Catalin

    2012-01-01

    Organic films can be produced either by MAPLE or directly by PLD (Pulsed laser deposition). For a reasonable deposition rate of ng/cm2 per pulse for film production by MAPLE a fluence of 1-1.5 J/cm2 is required at the laser wavelength of 355 nm, while the fluence can be considerably lower at 248 nm....... At high fluence the deposition rate of proteins by MAPLE seems to decrease. The surface roughness is still an issue, but at low fluence it seems to be acceptable. The fragmentation rate increases with fluence, and seems to be less pronounced for MAPLE than for PLD. Also this issue is not yet resolved....

  6. Edge reactivity and water-assisted dissociation on cobalt oxide nanoislands

    International Nuclear Information System (INIS)

    Fester, J.; García-Melchor, M.; Walton, A. S.; Bajdich, M.

    2017-01-01

    Here, transition metal oxides show great promise as Earth-abundant catalysts for the oxygen evolution reaction in electrochemical water splitting. However, progress in the development of highly active oxide nanostructures is hampered by a lack of knowledge of the location and nature of the active sites. Here we show, through atom-resolved scanning tunnelling microscopy, X-ray spectroscopy and computational modelling, how hydroxyls form from water dissociation at under coordinated cobalt edge sites of cobalt oxide nanoislands. Surprisingly, we find that an additional water molecule acts to promote all the elementary steps of the dissociation process and subsequent hydrogen migration, revealing the important assisting role of a water molecule in its own dissociation process on a metal oxide. Inspired by the experimental findings, we theoretically model the oxygen evolution reaction activity of cobalt oxide nanoislands and show that the nanoparticle metal edges also display favourable adsorption energetics for water oxidation under electrochemical conditions.

  7. Laser-assisted electron scattering in strong-field ionization of dense water vapor by ultrashort laser pulses

    International Nuclear Information System (INIS)

    Wilke, M; Al-Obaidi, R; Moguilevski, A; Kothe, A; Engel, N; Metje, J; Kiyan, I Yu; Aziz, E F

    2014-01-01

    We report on strong-field ionization of dense water gas in a short infrared laser pulse. By employing a unique combination of photoelectron spectroscopy with a liquid micro-jet technique, we observe how the character of electron emission at high kinetic energies changes with the increase of the medium density. This change is associated with the process of laser-assisted electron scattering (LAES) on neighboring particles, which becomes a dominant mechanism of hot electron emission at higher medium densities. The manifestation of this mechanism is found to require densities that are orders of magnitude lower than those considered for heating the laser-generated plasmas via the LAES process. The experimental results are supported by simulations of the LAES yield with the use of the Kroll–Watson theory. (paper)

  8. Pulse-reverse electrodeposition for mesoporous metal films: combination of hydrogen evolution assisted deposition and electrochemical dealloying.

    Science.gov (United States)

    Cherevko, Serhiy; Kulyk, Nadiia; Chung, Chan-Hwa

    2012-01-21

    Hydrogen evolution assisted electrodeposition is a new bottom-up technique allowing the fast and simple synthesis of nanometals. Electrochemical dealloying is a top-down approach with the same purpose. In this work, we show that a combination of these two methods in sequence by pulse-reverse electrodeposition can be used to prepare high-surface-area nanostructured metals. Highly porous adherent platinum is obtained by the deposition of CuPt alloy during the cathodic cycles and the selective dissolution of copper during the anodic cycles. The convection created by the movement of the hydrogen bubbles increases the deposition rate and removes the dissolved copper ions from the diffusion layer, which ensures the deposition of a film with the same stoichiometry throughout the whole process. Due to the relatively high ratio of copper atoms on the surface in the as-deposited layer, it is proposed that the dealloying kinetics is significantly higher than that usually observed during the dealloying process in a model system. The proposed approach has several advantages over other methods, such as a very high growth rate and needlessness of any post-treatment processes. A detailed analysis of the effect of pulse-reverse waveform parameters on the properties of the films is presented. Mesoporous platinum with pores and ligaments having characteristic sizes of less than 10 nm, an equivalent surface area of up to ca. 220 m(2) cm(-3), and a roughness factor of more than 1000 is fabricated.

  9. Surfactant assisted pulsed two-phase electromembrane extraction followed by GC analysis for quantification of basic drugs in biological samples.

    Science.gov (United States)

    Zahedi, Pegah; Davarani, Saied Saeed Hosseiny; Moazami, Hamid Reza; Nojavan, Saeed

    2016-01-05

    In this work, a simple and efficient surfactant assisted pulsed two-phase electromembrane extraction (SA-PEME) procedure combined with gas chromatography (GC) has been developed for the determination of alfentanil, sufentanil and methadone in various samples. It has been found that the addition of anionic surfactant causes the accumulation of the cationic analytes at the SLM/solution interface resulting in an easier transfer of the analytes into the organic phase. The method was accomplished with 1-octanol as the acceptor phase and supported liquid membrane (SLM) by means of an 80 V pulsed electrical driving force and the extraction time of 20 min. The model analytes were extracted from 3.0 mL sample solution (pH 4.0) containing 0.02% w/v surfactant (sodium dodecyl sulfate). The duty cycle of 92% and frequency of 0.357 Hz gave the best performance. Extraction recoveries in the range of 70.5-95.2% and satisfactory repeatability (7.6samples. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Binary Solvent Extraction System and Extraction Time Effects on Phenolic Antioxidants from Kenaf Seeds (Hibiscus cannabinus L.) Extracted by a Pulsed Ultrasonic-Assisted Extraction

    OpenAIRE

    Yu Hua Wong; Hwee Wen Lau; Chin Ping Tan; Kamariah Long; Kar Lin Nyam

    2014-01-01

    The aim of this study was to determine the best parameter for extracting phenolic-enriched kenaf (Hibiscus cannabinus L.) seeds by a pulsed ultrasonic-assisted extraction. The antioxidant activities of ultrasonic-assisted kenaf seed extracts (KSE) were determined by a 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity assay, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging assay, β -carotene bleaching inhibition assay, and ferric reducing antioxi...

  11. C-phycocyanin extraction assisted by pulsed electric field from Artrosphira platensis.

    Science.gov (United States)

    Martínez, Juan Manuel; Luengo, Elisa; Saldaña, Guillermo; Álvarez, Ignacio; Raso, Javier

    2017-09-01

    This paper assesses the application of pulsed electric fields (PEF) to the fresh biomass of Artrhospira platensis in order to enhance the extraction of C-phycocyanin into aqueous media. Electroporation of A. platensis depended on both electric field strength and treatment duration. The minimum electric field intensity for detecting C-phycocyanin in the extraction medium was 15kV/cm after the application of a treatment time 150μs (50 pulses of 3μs). However higher electric field strength were required when shorter treatment times were applied. Response surface methodology was used in order to investigate the influence of electric field strength (15-25kV/cm), treatment time (60-150μs), and temperature of application of PEF (10-40°C) on C-phycocyanin extraction yield (PEY). The increment of the temperature PEF treatment reduced the electric field strength and the treatment time required to obtain a given PEY and, consequently decreased the total specific energy delivered by the treatment. For example, the increment of temperature from 10°C to 40°C permitted to reduce the electric field strength required to extract 100mg/g d w of C-phycocyanin from 25 to 18kV/cm, and the specific energy input from 106.7 to 67.5kJ/Kg. Results obtained in this investigation demonstrated PEF's potential for selectively extraction C-phycocyanin from fresh A. platensis biomass. The purity of the C-phycocyanin extract obtained from the electroporated cells was higher than that obtained using other techniques based on the cell complete destruction. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Production and correlation of reactive oxygen and nitrogen species in gas- and liquid-phase generated by helium plasma jets under different pulse widths

    Science.gov (United States)

    Liu, Zhijie; Zhou, Chunxi; Liu, Dingxin; Xu, Dehui; Xia, Wenjie; Cui, Qingjie; Wang, Bingchuan; Kong, Michael G.

    2018-01-01

    In this paper, we present the effects of the pulse width (PW) on the plasma jet's discharge characteristics, particularly focusing on the production and correlation of the reactive oxygen and nitrogen species (RONS) in gas- and liquid-phase. It is found that the length of plasma jet plume first increases before the PW of 10 μs, then gradually decreases and finally almost remains unchanged beyond 150 μs. The plasma bullet disappears after the falling edge of the voltage pulse at low PW, while it terminates far ahead of the falling edge of voltage pulse at high PW. This is mainly attributed to accumulation of space charges that lead to weakening of the reduced electric field with an increase of PW from low to high. More important, it is found that the excited reactive species, the positive and negative ions from plasma jet, and the concentrations of NO2- and NO3- in deionized water exposed to plasma jet also display the first increasing and then decreasing change trend with increase of PW, while the concentration of H2O2 in water almost displays the linearly increasing trend. This mainly results from the formation of the H3O+ and HO2-, as well as their ion water clusters that can produce more OH radicals to be converted into H2O2, while the NO2- and NO3- in gas phase can transport into water and exist most stably in water. The water cluster formation at gas-liquid interface is an important key process that can affect the chemical nature and dose of aqueous RONS in water; this is beneficial for understanding how the RONS are formed in liquid-phase.

  13. High-rate deposition of photocatalytic TiO2 films by oxygen plasma assist reactive evaporation method

    International Nuclear Information System (INIS)

    Sakai, Tetsuya; Kuniyoshi, Yuji; Aoki, Wataru; Ezoe, Sho; Endo, Tatsuya; Hoshi, Yoichi

    2008-01-01

    High-rate deposition of titanium dioxide (TiO 2 ) film was attempted using oxygen plasma assisted reactive evaporation (OPARE) method. Photocatalytic properties of the film were investigated. During the deposition, the substrate temperature was fixed at 400 deg. C. The film deposition rate can be increased by increasing the supply of titanium atoms to the substrate, although oversupply of the titanium atoms causes oxygen deficiency in the films, which limits the deposition rate. The film structure depends strongly on the supply ratio of oxygen molecules to titanium atoms O 2 /Ti and changes from anatase to rutile structure as the O 2 /Ti supply ratio increased. Consequently, the maximum deposition rates of 77.0 nm min -1 and 145.0 nm min -1 were obtained, respectively, for the anatase and rutile film. Both films deposited at such high rates showed excellent hydrophilicity and organic decomposition performance. Even the film with rutile structure deposited at 145.0 nm min -1 had a contact angle of less than 2.5 deg. by UV irradiation for 5.0 h and an organics-decomposition performance index of 8.9 [μmol l -1 min -1 ] for methylene blue

  14. Pulsed counter-current ultrasound-assisted extraction and characterization of polysaccharides from Boletus edulis.

    Science.gov (United States)

    You, Qinghong; Yin, Xiulian; Ji, Chaowen

    2014-01-30

    Four methods for extracting polysaccharides from Boletus edulis, namely, hot-water extraction, ultrasonic clearer extraction, static probe ultrasonic extraction, and pulsed counter-current probe ultrasonic extraction (CCPUE), were studied. Results showed that CCPUE has the highest extraction efficiency among the methods studied. Under optimal CCPUE conditions, a B. edulis polysaccharide (BEP) yield of 8.21% was obtained. Three purified fractions, BEP-I, BEP-II, and BEP-III, were obtained through sequential purification by DEAE-52 and Sephadex G-75 chromatography. The average molecular weights of BEP-I, BEP-II, and BEP-III were 10,278, 23,761, and 42,736 Da, respectively. The polysaccharides were mainly composed of xylose, mannose, galactose, and glucose; of these, mannose contents were the highest. The antioxidant activities of the BEPs were further investigated by measurement of their ability to scavenge DPPH and hydroxyl radicals as well as their reducing power. The results indicated that the BEPs have good antioxidant activity. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. Pulsed ion beam-assisted carburizing of titanium in methane discharge

    International Nuclear Information System (INIS)

    Shafiq, M.; Shahzad, K.; Zakaullah, M.; Hassan, M.; Qayyum, A.; Ahmad, S.; Rawat, R. S.

    2010-01-01

    The carburizing of titanium (Ti) is accomplished by utilizing energetic ion pulses of a 1.5 kJ Mather type dense plasma focus (DPF) device operated in methane discharge. X-ray diffraction (XRD) analysis confirms the deposition of polycrystalline titanium carbide (TiC). The samples carburized at lower axial and angular positions show an improved texture for a typical (200)TiC plane. The Williamson–Hall method is employed to estimate average crystallite size and microstrains in the carburized Ti surface. Crystallite size is found to vary from ∼ 50 to 100 nm, depending on the deposition parameters. Microstrains vary with the sample position and hence ion flux, and are converted from tensile to compressive by increasing the flux. The carburizing of Ti is confirmed by two major doublets extending from 300 to 390 cm −1 and from 560 to 620 cm −1 corresponding to acoustic and optical active modes in Raman spectra, respectively. Analyses by scanning electron microscopy/energy dispersive x-ray spectroscopy (SEM/EDS) have provided qualitative and quantitative profiles of the carburized surface. The Vickers microhardness of Ti is significantly improved after carburizing. (nuclear physics)

  16. Stoichiometry and characterization of aluminum oxynitride thin films grown by ion-beam-assisted pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Zabinski, J.S. [Materials and Manufacturing Directorate, Air Force Research Laboratory (AFRL), Wright-Patterson Air Force Base, Dayton, Ohio 45433 (United States); Hu, J.J. [Materials and Manufacturing Directorate, Air Force Research Laboratory (AFRL), Wright-Patterson Air Force Base, Dayton, Ohio 45433 (United States)], E-mail: Jianjun.Hu@WPAFB.AF.MIL; Bultman, J.E. [Materials and Manufacturing Directorate, Air Force Research Laboratory (AFRL), Wright-Patterson Air Force Base, Dayton, Ohio 45433 (United States); Pierce, N.A. [Propulsion Directorate, Air Force Research Laboratory (AFRL), Wright-Patterson Air Force Base, Dayton, Ohio 45433 (United States); Voevodin, A.A. [Materials and Manufacturing Directorate, Air Force Research Laboratory (AFRL), Wright-Patterson Air Force Base, Dayton, Ohio 45433 (United States)

    2008-07-31

    Oxides are inherently stable in air at elevated temperatures and may serve as wear resistant matrices for solid lubricants. Aluminum oxide is a particularly good candidate for a matrix because it has good diffusion barrier properties and modest hardness. Most thin film deposition techniques that are used to grow alumina require high temperatures to impart crystallinity. Crystalline films are about twice as hard as amorphous ones. Unfortunately, the mechanical properties of most engineering steels are degraded at temperatures above 250-350 deg. C. This work is focused on using energetic reactive ion bombardment during simultaneous pulsed laser deposition to enhance film crystallization at low temperatures. Alumina films were grown at several background gas pressures and temperatures, with and without Ar ion bombardment. The films were nearly stoichiometric except for depositions in vacuum. Using nitrogen ion bombardment, nitrogen was incorporated into the films and formed the Al-O-N matrix. Nitrogen concentration could be controlled through selection of gas pressure and ion energy. Crystalline Al-O-N films were grown at 330 deg. C with a negative bias voltage to the substrate, and showed improved hardness in comparison to amorphous films.

  17. Studies on the reactive pulsed-magnetron sputtering of ITO from metallic targets; Untersuchungen zum reaktiven Pulsmagnetronsputtern von ITO von metallischen Targets

    Energy Technology Data Exchange (ETDEWEB)

    Gnehr, W.M.

    2006-06-15

    The thesis deals with a reactive sputter process for the deposition of ITO- films. In contrast to the usual technique, the sputter targets consists of indium-tin-alloy instead of ceramic ITO. All experiments were conducted on an inline coater with 600 mm target-width. The process is stabilized by a control loop based on optical emission detection. The experiments prove, that this control loop guarantees a long term stability of the outcomes of the coating process.Process parameters, that are crucial for the optical and electrical properties of the deposited thin films are identified and studied. Among them are the flow of oxygen and the substrate temperature but also less obvious parameters such as the distance between target and substrate.Througout the work the focus is on the film deposition with pulsed plasmas. Novel bipolar DC pulse- and pulse package generators are employed for the deposition.In order to shed some light onto the influence of certain pulse parameters on the outcome of a particular coating process, a Monte-Carlo-Simulation of the particle flow in pulsed plasmas is developed. This simulation yields the distribution of particles and their respective energies on deliberately placed planes in the process chamber. Particles under investigation are both sputtered species and neutral sputter gas atoms reflected at the target. The results of this simulation provide an explanation for the influence of certain pulse parameters on the outcome of the coating process. The further investigations deal with the influence of the construction of the process chamber on the coating process. For this purpose, locally resolved optical spectra are recorded. In order to analyse these spectra, a novel connected fit algorithm is developed.This algorithm yields the distribution of certain fitparameters on the substrate. Provided the most complex of the discussed parametrizations of the dielectric function are used, these can be crucial properties such as the carrier

  18. Chemical analysis of reactive species and antimicrobial activity of/nwater treated by nanosecond pulsed DBD air plasma

    Czech Academy of Sciences Publication Activity Database

    Laurita, R.; Barbieri, D.; Gherardi, M.; Colombo, V.; Lukeš, Petr

    2015-01-01

    Roč. 3, č. 2 (2015), s. 53-61 ISSN 2212-8166 R&D Projects: GA MŠk(CZ) LD14080 Grant - others:European Cooperation in Science and Technology(XE) COST TD1208 Institutional support: RVO:61389021 Keywords : Dielectric barrier discharge * Plasma activated water * Reactive species * Peroxynitrite * Phenol degradation * Candida albicans * Staphylococcus aureus * Antimicrobial activity * Nosocomial infections Subject RIV: BL - Plasma and Gas Discharge Physics http://www.sciencedirect.com/science/article/pii/S2212816615300081

  19. Optical emission and mass spectroscopy of plasma processes in reactive DC pulsed magnetron sputtering of aluminium oxide

    Czech Academy of Sciences Publication Activity Database

    Novotný, Michal; Bulíř, Jiří; Pokorný, Petr; Bočan, Jiří; Fitl, Přemysl; Lančok, Ján; Musil, Jindřich

    2010-01-01

    Roč. 12, č. 3 (2010), 697-700 ISSN 1454-4164 R&D Projects: GA AV ČR IAA100100718; GA AV ČR KAN400100653; GA ČR GP202/09/P324 Institutional research plan: CEZ:AV0Z10100522 Keywords : reactive magnetron sputtering * alumina * plasma spectroscopy * mass spectroscopy * optical emission spectroscopy Subject RIV: BH - Optics, Masers, Lasers Impact factor: 0.412, year: 2010

  20. Investigation of reactivity of inorganic free radicals relative to ferrocyanide- and octacyanomolybdate-ions in aqueous solutions by the method of pulse radiolysis

    International Nuclear Information System (INIS)

    Gogolev, A.V.; Fedoseev, A.M.; Makarov, I.F.; Pikaev, A.K.

    1989-01-01

    In aqueous solutions by the method of pulse radiolysis (dose per impulse-7.96-47.8 Gy, electron energy-5 MeV) the reactivity of Cl 2 - , Br 2 - , I 2 - , (SCN) 2 - , CO 3 - , SeO 3 - , SO 4 - radicals towards ferrocyanide ions and of Br 2 - , CO 3 - , SO 4 - radicals tawards octacyanomolybdate ions is studied. Linear dependence of rate constant logarithm of Cl 2 - , Br 2 - , I 2 - reactions with cyanide complexes on the difference of redox potentials of reacting particles ΔE 0 is obtained. Radicals containing oxygen react with cyanide complexes more rapidly than can be expected on the basis of ΔE 0 values. The effect of solution ionic strength, charge of reacting particles and radical nature on the reaction rate is discussed

  1. Studies of the composition, tribology and wetting behavior of silicon nitride films formed by pulsed reactive closed-field unbalanced magnetron sputtering

    International Nuclear Information System (INIS)

    Yao, Zh.Q.; Yang, P.; Huang, N.; Wang, J.; Wen, F.; Leng, Y.X.

    2006-01-01

    Silicon nitride films were formed by pulsed reactive closed-field unbalanced magnetron sputtering of high purity Si targets in an Ar-N 2 mixture. The effects of N 2 fraction on the chemical composition, and tribological and wetting behaviors were investigated. The films deposited at a high N 2 fraction were consistently N-rich. The surface microstructure changed from continuous granular surrounded by tiny void regions to a homogeneous and dense microstructure, and densitied as the N 2 fraction is increased. The as-deposited films have a relatively low friction coefficient and better wear resistance than 316L stainless steel under dry sliding friction and experienced only abrasive wear. The decreased surface roughness and increased nitrogen incorporation in the film give rise to increased contact angle with double-stilled water from 24 deg. to 49.6 deg. To some extent, the silicon nitride films deposited are hydrophilic in nature

  2. Oxygen diffusion kinetics and reactive lifetimes in bacterial and mammalian cells irradiated with nanosecond pulses of high intensity electrons

    International Nuclear Information System (INIS)

    Epp, E.R.; Weiss, H.; Ling, C.C.; Djordjevic, B.; Kessaris, N.D.

    1975-01-01

    Experiaments have been designed to gain information on the lifetime of oxygen-sensitive species suspected to be produced in critical molecules in irradiated cells and on the time-diffusion of oxygen in cells. An approach developed in this laboratory involves the delivery of two high intensity electron pulses each of 3 ns duration to a thin layer of cells equilibrated with a known concentration of oxygen. The first pulse serves to render the cells totally anoxic by the radiochemical depletion of oxygen; the second is delivered at a time electronically delayed after the first allowing for diffusion of oxygen during this time. Under these conditions the radiosensitivity of E coli B/r has been measured over six decades of interpulse time. Cellular time-diffusion curves constructed from the measurements show that oxygen establishes its sensitizing effect within 10 -4 s after the creation of intracellular anoxia establishing this time as an upper limit to the lifetime of the species. Unusual behaviour of the diffusion curve observed for longer delay times can be explained by a model wherein it is postulated that a radiation-induced inhibiting agent slows down diffusion. Application of this model to the experimental data yields a value of 0.4x10 -5 cm 2 s -1 for the cellular oxygen diffusion coefficient. Similar experiments recently carried out for Serratia marcescens will also be described. The oxygen effect in cultured HeLa cells exposed to single short electron pulses has been examined over a range of oxygen concentrations. A family of breaking survival curves was obtained similar to those previously measured for E coli B/r by this laboratory. The data appear to be reasonably consistent with a physicochemical mechanism involving the radiochemical depletion of oxygen previously invoked for bacteria. (author)

  3. Reactivity of OH radicals with chlorobenzoic acids-A pulse radiolysis and steady-state radiolysis study

    DEFF Research Database (Denmark)

    Zona, Robert; Solar, Sonja; Getoff, Nikola

    2010-01-01

    The reactions of OH radicals with 2-, 3-, 4-chlorobenzoic acids (ClBzA) and chlorobenzene (ClBz), k(OH+substrates)=(4.5−6.2)×109 dm3 mol−1 s−1, have been studied by pulse radiolysis in N2O saturated solutions. The absorption maxima of the OH-adducts were in the range of 320−340 nm. Their decay wa...... to degradation. The order for the efficiency of dehalogenation was 4->2->3-ClBzA. Several primary radiolytic products could be detected by HPLC. To evaluate the toxicity of final products a bacterial bioluminescence test was carried out....

  4. Deposition of organic dyes for dye-sensitized solar cell by using matrix-assisted pulsed laser evaporation

    Directory of Open Access Journals (Sweden)

    Chih-Ping Yen

    2016-08-01

    Full Text Available The deposition of various distinct organic dyes, including ruthenium complex N3, melanin nanoparticle (MNP, and porphyrin-based donor-π-acceptor dye YD2-o-C8, by using matrix-assisted pulsed laser evaporation (MAPLE for application to dye-sensitized solar cell (DSSC is investigated systematically. It is found that the two covalently-bonded organic molecules, i.e., MNP and YD2-o-C8, can be transferred from the frozen target to the substrate with maintained molecular integrity. In contrast, N3 disintegrates in the process, presumably due to the lower bonding strength of metal complex compared to covalent bond. With the method, DSSC using YD2-o-C8 is fabricated, and an energy conversion efficiency of 1.47% is attained. The issue of the low penetration depth of dyes deposited by MAPLE and the possible resolution to it are studied. This work demonstrates that MAPLE could be an alternative way for deposition of organic dyes for DSSC.

  5. Study of titania nanorod films deposited by matrix-assisted pulsed laser evaporation as a function of laser fluence

    Science.gov (United States)

    Caricato, A. P.; Belviso, M. R.; Catalano, M.; Cesaria, M.; Cozzoli, P. D.; Luches, A.; Manera, M. G.; Martino, M.; Rella, R.; Taurino, A.

    2011-11-01

    Chemically synthesized brookite titanium dioxide (TiO2) nanorods with average diameter and length dimensions of 3-4 nm and 35-50 nm, respectively, were deposited by the matrix-assisted pulsed laser evaporation technique. A toluene nanorod solution was frozen at the liquid-nitrogen temperature and irradiated with a KrF excimer laser ( λ=248 nm, τ=20 ns) at the repetition rate of 10 Hz, at different fluences (25 to 350 mJ/cm2). The deposited films were structurally characterized by high-resolution scanning and transmission electron microscopy. single-crystal Si wafers and carbon-coated Cu grids were used as substrates. Structural analyses evidenced the occurrence of brookite-phase crystalline nanospheres coexisting with individually distinguishable TiO2 nanorods in the films deposited at fluences varying from 50 to 350 mJ/cm2. Nanostructured TiO2 films comprising only nanorods were deposited by lowering the laser fluence to 25 mJ/cm2. The observed shape and phase transitions of the nanorods are discussed taking into account the laser-induced heating effects, reduced melting temperature and size-dependent thermodynamic stability of nanoscale TiO2.

  6. Time-Resolved Quantum Cascade Laser Absorption Spectroscopy of Pulsed Plasma Assisted Chemical Vapor Deposition Processes Containing BCl3

    Science.gov (United States)

    Lang, Norbert; Hempel, Frank; Strämke, Siegfried; Röpcke, Jürgen

    2011-08-01

    In situ measurements are reported giving insight into the plasma chemical conversion of the precursor BCl3 in industrial applications of boriding plasmas. For the online monitoring of its ground state concentration, quantum cascade laser absorption spectroscopy (QCLAS) in the mid-infrared spectral range was applied in a plasma assisted chemical vapor deposition (PACVD) reactor. A compact quantum cascade laser measurement and control system (Q-MACS) was developed to allow a flexible and completely dust-sealed optical coupling to the reactor chamber of an industrial plasma surface modification system. The process under the study was a pulsed DC plasma with periodically injected BCl3 at 200 Pa. A synchronization of the Q-MACS with the process control unit enabled an insight into individual process cycles with a sensitivity of 10-6 cm-1·Hz-1/2. Different fragmentation rates of the precursor were found during an individual process cycle. The detected BCl3 concentrations were in the order of 1014 molecules·cm-3. The reported results of in situ monitoring with QCLAS demonstrate the potential for effective optimization procedures in industrial PACVD processes.

  7. Deposition of organic dyes for dye-sensitized solar cell by using matrix-assisted pulsed laser evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Yen, Chih-Ping [Department of Physics, National Taiwan University, Taipei 106, Taiwan (China); Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan (China); Yu, Pin-Feng [Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan (China); Department of Physics, National Chung Cheng University, Chiayi 621, Taiwan (China); Wang, Jyhpyng [Department of Physics, National Taiwan University, Taipei 106, Taiwan (China); Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan (China); Department of Physics, National Central University, Taoyuan 320, Taiwan (China); Lin, Jiunn-Yuan [Department of Physics, National Chung Cheng University, Chiayi 621, Taiwan (China); Chen, Yen-Mu [SuperbIN Co., Ltd., Taipei 114, Taiwan (China); Chen, Szu-yuan, E-mail: sychen@ltl.iams.sinica.edu.tw [Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan (China); Department of Physics, National Central University, Taoyuan 320, Taiwan (China)

    2016-08-15

    The deposition of various distinct organic dyes, including ruthenium complex N3, melanin nanoparticle (MNP), and porphyrin-based donor-π-acceptor dye YD2-o-C8, by using matrix-assisted pulsed laser evaporation (MAPLE) for application to dye-sensitized solar cell (DSSC) is investigated systematically. It is found that the two covalently-bonded organic molecules, i.e., MNP and YD2-o-C8, can be transferred from the frozen target to the substrate with maintained molecular integrity. In contrast, N3 disintegrates in the process, presumably due to the lower bonding strength of metal complex compared to covalent bond. With the method, DSSC using YD2-o-C8 is fabricated, and an energy conversion efficiency of 1.47% is attained. The issue of the low penetration depth of dyes deposited by MAPLE and the possible resolution to it are studied. This work demonstrates that MAPLE could be an alternative way for deposition of organic dyes for DSSC.

  8. Temperature responsive functional polymeric thin films obtained by matrix assisted pulsed laser evaporation for cells attachment–detachment study

    Energy Technology Data Exchange (ETDEWEB)

    Rusen, L. [NILPRP, National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Street, PO Box MG-16, RO-077125 Magurele, Bucharest (Romania); Dinca, V., E-mail: dinali@nipne.ro [NILPRP, National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Street, PO Box MG-16, RO-077125 Magurele, Bucharest (Romania); Mitu, B. [NILPRP, National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Street, PO Box MG-16, RO-077125 Magurele, Bucharest (Romania); Mustaciosu, C. [Horia Hulubei National Institute of Physics and Nuclear Engineering, IFIN HH, Magurele, Bucharest (Romania); Dinescu, M. [NILPRP, National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Street, PO Box MG-16, RO-077125 Magurele, Bucharest (Romania)

    2014-05-01

    Multifunctional thin films used as thermoresponsive substrate for engineering cell sheets represent an important area in tissue engineering. As the morphology and the chemical characteristics of the thin films directly control their interaction with cells, it is important to correlate these characteristics with the biological answer. In this study, thermally sensitive poly(N-isopropylacrylamide), (pNIPAAm) thin films were prepared by matrix assisted pulsed laser evaporation and utilized in L929 cell adhesion and detachment studies. Fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM) were used to determine the pNIPAAm thin films chemical and morphological characteristics. The FTIR data demonstrated that the functional groups in the MAPLE-deposited films remained intact for fluences in the range of 200–600 mJ cm{sup −2}. Within this fluence range, the AFM topographical studies showed that the roughness of the coatings was dependent on laser fluence and the obtained surfaces were characterized by a granular aspect. L929 cell viability studies onto the pNIPAAm coatings showed little or no toxic effect for fluences below 600 mJ cm{sup −2}, while for higher fluences, viability was decreased with more than 50%. The adhesion and detachment of the cell was found to be mainly dependent on the film surface morphology.

  9. Thin films of polymer blends deposited by matrix-assisted pulsed laser evaporation: Effects of blending ratios

    International Nuclear Information System (INIS)

    Paun, Irina Alexandra; Ion, Valentin; Moldovan, Antoniu; Dinescu, Maria

    2011-01-01

    In this work, we show successful use of matrix-assisted pulsed laser evaporation (MAPLE) for obtaining thin films of PEG:PLGA blends, in the view of their use for controlled drug delivery. In particular, we investigate the influence of the blending ratios on the characteristics of the films. We show that the roughness of the polymeric films is affected by the ratio of each polymer within the blend. In addition, we perform Fourier transformed infrared spectroscopy (FTIR) measurements and we find that the intensities ratios of the infrared absorption bands of the two polymers are consistent with the blending ratios. Finally, we assess the optical constants of the polymeric films by spectroscopic ellipsometry (SE). We point out that the blending ratios exert an influence on the optical characteristics of the films and we validate the SE results by atomic force microscopy and UV-vis spectrophotometry. In all, we stress that the ratios in which the two polymers are blended have significant impact on the morphology, chemical structure and optical characteristics of the polymeric films deposited by MAPLE.

  10. Composite biocompatible hydroxyapatite-silk fibroin coatings for medical implants obtained by Matrix Assisted Pulsed Laser Evaporation

    International Nuclear Information System (INIS)

    Miroiu, F.M.; Socol, G.; Visan, A.; Stefan, N.; Craciun, D.; Craciun, V.; Dorcioman, G.; Mihailescu, I.N.; Sima, L.E.; Petrescu, S.M.; Andronie, A.; Stamatin, I.; Moga, S.; Ducu, C.

    2010-01-01

    The aim of this study was to obtain biomimetic inorganic-organic thin films as coatings for metallic medical implants. These contain hydroxyapatite, the inorganic component of the bony tissues, and a natural biopolymer - silk fibroin - added in view to induce the surface functionalization. Hydroxyapatite (HA), silk fibroin (FIB) and composite HA-FIB films were obtained by Matrix Assisted Pulsed Laser Evaporation (MAPLE) in order to compare their physical and biological performances as coatings on metallic prostheses. We used an excimer laser source (KrF*, λ = 248 nm, τ = 25 ns) operated at 10 Hz repetition rate. Coatings were deposited on quartz, Si and Ti substrates and then subjected to physical (FTIR, XRD, AFM, SEM) analyses, correlated with the results of the cytocompatibility in vitro tests. The hybrid films were synthesized from frozen targets of aqueous suspensions with 3:2 or 3:4 weight ratio of HA:FIB. An appropriate stoichiometric and functional transfer was obtained for 0.4-0.5 J/cm 2 laser fluence. FTIR spectra of FIB and HA-FIB films exhibited distinctive absorption maxima, in specific positions of FIB random coil form: 1540 cm -1 amide II, 1654 cm -1 amide I, 1243 cm -1 amide III, while the peak from 1027 cm -1 appeared only for HA and composite films. Osteosarcoma SaOs2 cells cultured 72 h on FIB and HA-FIB films showed increased viability, good spreading and normal cell morphology. The well-elongated, flattened cells are a sign of an appropriate interaction with the MAPLE FIB and composite HA-FIB coatings.

  11. Composite biocompatible hydroxyapatite-silk fibroin coatings for medical implants obtained by Matrix Assisted Pulsed Laser Evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Miroiu, F.M., E-mail: marimona.miroiu@inflpr.ro [National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, RO-77125, MG-36, Magurele-Ilfov (Romania); Socol, G.; Visan, A.; Stefan, N.; Craciun, D.; Craciun, V.; Dorcioman, G.; Mihailescu, I.N. [National Institute for Lasers, Plasma, and Radiation Physics, 409 Atomistilor Street, RO-77125, MG-36, Magurele-Ilfov (Romania); Sima, L.E.; Petrescu, S.M. [Institute of Biochemistry, Romanian Academy, 296 Splaiul Independentei, 060031 Bucharest (Romania); Andronie, A.; Stamatin, I. [3Nano-SAE Alternative Energy Sources-University of Bucharest, Faculty of Physics, 409 Atomistilor Street, RO-77125, Magurele-Ilfov (Romania); Moga, S.; Ducu, C. [University of Pitesti, Targul din Vale Str, no. 1, 110040 Pitesti (Romania)

    2010-05-25

    The aim of this study was to obtain biomimetic inorganic-organic thin films as coatings for metallic medical implants. These contain hydroxyapatite, the inorganic component of the bony tissues, and a natural biopolymer - silk fibroin - added in view to induce the surface functionalization. Hydroxyapatite (HA), silk fibroin (FIB) and composite HA-FIB films were obtained by Matrix Assisted Pulsed Laser Evaporation (MAPLE) in order to compare their physical and biological performances as coatings on metallic prostheses. We used an excimer laser source (KrF*, {lambda} = 248 nm, {tau} = 25 ns) operated at 10 Hz repetition rate. Coatings were deposited on quartz, Si and Ti substrates and then subjected to physical (FTIR, XRD, AFM, SEM) analyses, correlated with the results of the cytocompatibility in vitro tests. The hybrid films were synthesized from frozen targets of aqueous suspensions with 3:2 or 3:4 weight ratio of HA:FIB. An appropriate stoichiometric and functional transfer was obtained for 0.4-0.5 J/cm{sup 2} laser fluence. FTIR spectra of FIB and HA-FIB films exhibited distinctive absorption maxima, in specific positions of FIB random coil form: 1540 cm{sup -1} amide II, 1654 cm{sup -1} amide I, 1243 cm{sup -1} amide III, while the peak from 1027 cm{sup -1} appeared only for HA and composite films. Osteosarcoma SaOs2 cells cultured 72 h on FIB and HA-FIB films showed increased viability, good spreading and normal cell morphology. The well-elongated, flattened cells are a sign of an appropriate interaction with the MAPLE FIB and composite HA-FIB coatings.

  12. Resonant Infrared Matrix-Assisted Pulsed Laser Evaporation Of Inorganic Nanoparticles And Organic/Inorganic Hybrid Nanocomposites

    Science.gov (United States)

    Pate, Ryan; Lantz, Kevin R.; Dhawan, Anuj; Vo-Dinh, Tuan; Stiff-Roberts, Adrienne D.

    2010-10-01

    In this research, resonant infrared matrix-assisted pulsed laser evaporation (RIR-MAPLE) has been used to deposit different classes of inorganic nanoparticles, including bare, un-encapsulated ZnO and Au nanoparticles, as well as ligand-encapsulated CdSe colloidal quantum dots (CQDs). RIR-MAPLE has been used for thin-film deposition of different organic/inorganic hybrid nanocomposites using some of these inorganic nanoparticles, including CdSe CQD-poly[2-methoxy-5-(2'-ethylhexyloxy)-1,4-(1-cyanovinylene)phenylene] (MEH-CN-PPV) nanocomposites and Au nanoparticle-poly(methyl methacrylate) (PMMA) nanocomposites. The unique contribution of this research is that a technique is demonstrated for the deposition of organic-based thin-films requiring solvents with bond energies that do not have to be resonant with the laser energy. By creating an emulsion of solvent and ice in the target, RIR-MAPLE using a 2.94 μm laser can deposit most material systems because the hydroxyl bonds in the ice component of the emulsion matrix are strongly resonant with the 2.94 μm laser. In this way, the types of materials that can be deposited using RIR-MAPLE has been significantly expanded. Furthermore, materials with different solvent bond energies can be co-deposited without concern for material degradation and without the need to specifically tune the laser energy to each material solvent bond energy, thereby facilitating the realization of organic/inorganic hybrid nanocomposite thin-films. In addition to the structural characterization of the inorganic nanoparticle and hybrid nanocomposite thin-films deposited using this RIR-MAPLE technique, optical characterization is presented to demonstrate the potential of such films for optoelectronic device applications.

  13. Resonant Infrared Matrix-Assisted Pulsed Laser Evaporation Of Inorganic Nanoparticles And Organic/Inorganic Hybrid Nanocomposites

    International Nuclear Information System (INIS)

    Pate, Ryan; Lantz, Kevin R.; Stiff-Roberts, Adrienne D.; Dhawan, Anuj; Vo-Dinh, Tuan

    2010-01-01

    In this research, resonant infrared matrix-assisted pulsed laser evaporation (RIR-MAPLE) has been used to deposit different classes of inorganic nanoparticles, including bare, un-encapsulated ZnO and Au nanoparticles, as well as ligand-encapsulated CdSe colloidal quantum dots (CQDs). RIR-MAPLE has been used for thin-film deposition of different organic/inorganic hybrid nanocomposites using some of these inorganic nanoparticles, including CdSe CQD-poly[2-methoxy-5-(2'-ethylhexyloxy )-1,4-(1-cyanovinylene)phenylene](MEH-CN-PPV) nanocomposites and Au nanoparticle-poly(methyl methacrylate)(PMMA) nanocomposites. The unique contribution of this research is that a technique is demonstrated for the deposition of organic-based thin-films requiring solvents with bond energies that do not have to be resonant with the laser energy. By creating an emulsion of solvent and ice in the target, RIR-MAPLE using a 2.94 μm laser can deposit most material systems because the hydroxyl bonds in the ice component of the emulsion matrix are strongly resonant with the 2.94 μm laser. In this way, the types of materials that can be deposited using RIR-MAPLE has been significantly expanded. Furthermore, materials with different solvent bond energies can be co-deposited without concern for material degradation and without the need to specifically tune the laser energy to each material solvent bond energy, thereby facilitating the realization of organic/inorganic hybrid nanocomposite thin-films. In addition to the structural characterization of the inorganic nanoparticle and hybrid nanocomposite thin-films deposited using this RIR-MAPLE technique, optical characterization is presented to demonstrate the potential of such films for optoelectronic device applications.

  14. Tube Inner Coating of Non-Conductive Films by Pulsed Reactive Coaxial Magnetron Plasma with Outer Anode

    Directory of Open Access Journals (Sweden)

    Musab Timan Idriss Gasab

    2018-03-01

    Full Text Available The double-ended coaxial magnetron pulsed plasma (DCMPP method with auxiliary outer anode was introduced in order to achieve the uniform coating of non-conductive thin films on the inner walls of insulator tubes. In this study, titanium (Ti was employed as a cathode (sputtering target, and a glass tube was used as a substrate. In an argon (Ar and oxygen (O2 gas mixture, magnetron plasma was generated. Oxygen gas was introduced to deposit a titanium oxide (TiO2 film. A comparison between films coated with and without an auxiliary outer anode was made. As a result, it was clearly shown that the DCMPP method using an auxiliary outer anode enhanced the uniformity of the deposited non-conductive film compared to the conventional DCMPP method. Moreover, the optimum conditions under which the thin TiO2 film was deposited on the inner wall of the glass tube were revealed. From the results, it was supposed that the auxiliary outer anode contributed to the uniformity of the distributions of deposited negative charge on the non-conductive film and consequently the electric field and the plasma density uniform.

  15. Study by γ radiolysis and pulsed radiolysis of the reactivity of the superoxide ion in the oxyhemoglobin-methemoglobin system

    International Nuclear Information System (INIS)

    Haristoy, Didier.

    1976-01-01

    γ radiolysis of aqueous solutions of methemoglobin (MetHb) in the presence of formate ions, shows that only 25% of the total protein is reduced in oxyhemoglobin (HbO 2 ) by superoxide ions O 2 - according to the reaction MetHb+O 2 - →HbO 2 . The result can be attributed neither to the reactions of O 2 - with HbO 2 , nor the oxidation of HbO 2 by H 2 O 2 produced in the radiolysis of water and by dismutation of O 2 - . Pulse radiolysis studies of this reaction strongly suggest the formation of a transient complex 'MetHbO 2 - ' during the reaction. In addition to the well known self-oxidation of HbO 2 , these results show the existence of an equilibrium between HbO 2 and MetHb+O 2 - . Such an equilibrium could give rise, 'in vivo' to a nearly steady concentration of superoxide ions which could initiate a reaction favoring oxidation by oxygen [fr

  16. Kinetic and mechanistic studies of reactive intermediates in photochemical and transition metal-assisted oxidation, decarboxylation and alkyl transfer reactions

    Energy Technology Data Exchange (ETDEWEB)

    Carraher, Jack McCaslin [Iowa State Univ., Ames, IA (United States)

    2014-01-01

    Reactive species like high-valent metal-oxo complexes and carbon and oxygen centered radicals are important intermediates in enzymatic systems, atmospheric chemistry, and industrial processes. Understanding the pathways by which these intermediates form, their relative reactivity, and their fate after reactions is of the utmost importance. Herein are described the mechanistic detail for the generation of several reactive intermediates, synthesis of precursors, characterization of precursors, and methods to direct the chemistry to more desirable outcomes yielding ‘greener’ sources of commodity chemicals and fuels.

  17. Reactivity of OH radicals with chlorobenzoic acids-A pulse radiolysis and steady-state radiolysis study

    Energy Technology Data Exchange (ETDEWEB)

    Zona, Robert [University of Vienna, Department of Nutritional Sciences, Section Radiation Biology, UZAII, Althanstrasse 14, A-1090 Vienna (Austria); Solar, Sonja, E-mail: sonja.solar@univie.ac.a [University of Vienna, Department of Nutritional Sciences, Section Radiation Biology, UZAII, Althanstrasse 14, A-1090 Vienna (Austria); Getoff, Nikola [University of Vienna, Department of Nutritional Sciences, Section Radiation Biology, UZAII, Althanstrasse 14, A-1090 Vienna (Austria); Sehested, Knud; Holcman, Jerzy [RISO National Laboratory Environmental Science and Technology Department, DK-4000, Roskilde (Denmark)

    2010-05-15

    The reactions of OH radicals with 2-, 3-, 4-chlorobenzoic acids (ClBzA) and chlorobenzene (ClBz), k({sup c}entre dotOH+substrates)=(4.5-6.2)x10{sup 9} dm{sup 3} mol{sup -1} s{sup -1}, have been studied by pulse radiolysis in N{sub 2}O saturated solutions. The absorption maxima of the OH-adducts were in the range of 320-340 nm. Their decay was according to a second-order reaction, 2k=(1-9)x10{sup 8} dm{sup 3} mol{sup -1} s{sup -1}. In the presence of N{sub 2}O/O{sub 2} the formation of peroxyl radicals was detectable for 2-, 4-ClBzA and ClBz, k(OH-adduct+O{sub 2})=(2-4)x10{sup 7} dm{sup 3} mol{sup -1} s{sup -1}, while this reaction for 3-ClBzA was too slow to be registered. In the presence of N{sub 2}O the degradation rates induced by gamma radiation were very similar for all chlorobenzoic acids, yet the chloride formation was distinctly higher for 3-ClBzA. In the presence of oxygen the initial degradation of 2-and 4-ClBzA equaled the OH-radical concentration, whereas in case of 3-ClBzA only approx60% of {sup c}entre dotOH led to degradation. The order for the efficiency of dehalogenation was 4->2->3-ClBzA. Several primary radiolytic products could be detected by HPLC. To evaluate the toxicity of final products a bacterial bioluminescence test was carried out.

  18. Design and preliminary characterization of a miniature pulsed RF APGD torch with downstream injection of the source of reactive species

    International Nuclear Information System (INIS)

    Leveille, V; Coulombe, S

    2005-01-01

    The design of a miniature low-power atmospheric pressure glow discharge torch (APGD-t) and the results of its preliminary electrical and spectroscopic characterization are presented. A capacitively-coupled pulsed RF (13.56 MHz) helium plasma jet is formed in a converging confinement tube and O 2 is injected downstream in the plasma afterglow region through a capillary electrode. With 1 SLM He, the APGD-t produced a non-thermal plasma jet of 500 μm-diameter and ∼2.5 mm-long at power levels ranging from 1 to 5 W. At ∼1 W, the gas temperature and He excitation temperature near the nozzle exit were ∼50 0 C and slightly below 2000 K, respectively. The breakdown voltage in 1 SLM He is approximately 220 V pk-to-0 . Careful electric probe measurements and circuit analysis revealed the strong effect of the voltage probe on the total load impedance. The injection of 10 SCCM O 2 through the capillary electrode led to the transport of atomic O further downstream in the plasma jet and to a slight increase of the He excitation temperature without significant effects on the electrical properties and jet length. Alternatively, the addition of an equivalent amount of O 2 (1 v/v%) to the plasma-forming gas affected the electrical properties slightly, but led to a drastic contraction of the plasma jet. The atomic oxygen production and transport conditions provided by the APGD-t are promising for precise bio-applications such as the treatment of skin tissues and cells

  19. Long-term clinical evaluation of a 800-nm long-pulsed diode laser with a large spot size and vacuum-assisted suction for hair removal.

    Science.gov (United States)

    Ibrahimi, Omar A; Kilmer, Suzanne L

    2012-06-01

    The long-pulsed diode (800-810-nm) laser is one of the most commonly used and effective lasers for hair removal. Limitations of currently available devices include a small treatment spot size, treatment-associated pain, and the need for skin cooling. To evaluate the long-term hair reduction capabilities of a long-pulsed diode laser with a large spot size and vacuum assisted suction. Thirty-five subjects were enrolled in a prospective, self-controlled, single-center study of axillary hair removal. The study consisted of three treatments using a long-pulsed diode laser with a large spot size and vacuum-assisted suction at 4- to 6-week intervals with follow-up visits 6 and 15 months after the last treatment. Hair clearance was quantified using macro hair-count photographs taken at baseline and at 6- and 15-month follow-up visits. Changes in hair thickness and color, levels of treatment-associated pain, and adverse events were additional study endpoints. There was statistically significant hair clearance at the 6 (54%) and 15-month (42%) follow-up visits. Remaining hairs were thinner and lighter at the 15-month follow-up visit, and the majority of subjects reported feeling up to mild to moderate pain during treatment without the use of pretreatment anesthesia or skin cooling. A long-pulsed diode laser with a large spot size and vacuum-assisted suction is safe and effective for long-term hair removal. This is the largest prospective study to evaluate long-term hair removal and the first to quantify decreases in hair thickness and darkness with treatment. © 2012 by the American Society for Dermatologic Surgery, Inc. Published by Wiley Periodicals, Inc.

  20. Improved irradiation tolerance of reactive gas pulse sputtered TiN coatings with a hybrid architecture of multilayered and compositionally graded structures

    Science.gov (United States)

    Liang, Wei; Yang, Jijun; Zhang, Feifei; Lu, Chenyang; Wang, Lumin; Liao, Jiali; Yang, Yuanyou; Liu, Ning

    2018-04-01

    This study investigates the improved irradiation tolerance of reactive gas pulse (RGP) sputtered TiN coatings which has hybrid architecture of multilayered and compositionally graded structures. The multilayered RGP-TiN coating is composed of hexagonal close-packed Ti phase and face-centred cubic TiN phase sublayers, where the former sublayer has a compositionally graded structure and the latter one maintains constant stoichiometric atomic ratio of Ti:N. After 100 keV He ion irradiation, the RGP-TiN coating exhibits improved irradiation resistance compared with its single layered (SL) counterpart. The size and density of He bubbles are smaller in the RGP-TiN coating than in the SL-TiN coating. The irradiation-induced surface blistering of the coatings shows a similar tendency. Meanwhile, the irradiation hardening and adhesion strength of the RGP-TiN coatings were not greatly affected by He irradiation. Moreover, the irradiation damage tolerance of the coatings can be well tuned by changing the undulation period number of N2 gas flow rate. Detailed analysis suggested that this improved irradiation tolerance could be related to the combined contribution of the multilayered and compositionally graded structures.

  1. Epitaxial growth of indium oxyfluoride thin films by reactive pulsed laser deposition: Structural change induced by fluorine insertion into vacancy sites in bixbyite structure

    Energy Technology Data Exchange (ETDEWEB)

    Okazaki, Sohei [Kanagawa Academy of Science and Technology (KAST), 3-2-1 Sakado, Takatsu-ku, Kawasaki 213-0012 (Japan); CREST, Japan Science and Technology Agency (JST), 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Hirose, Yasushi, E-mail: hirose@chem.s.u-tokyo.ac.jp [Kanagawa Academy of Science and Technology (KAST), 3-2-1 Sakado, Takatsu-ku, Kawasaki 213-0012 (Japan); CREST, Japan Science and Technology Agency (JST), 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Department of Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Nakao, Shoichiro [Kanagawa Academy of Science and Technology (KAST), 3-2-1 Sakado, Takatsu-ku, Kawasaki 213-0012 (Japan); CREST, Japan Science and Technology Agency (JST), 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Yang, Chang [Kanagawa Academy of Science and Technology (KAST), 3-2-1 Sakado, Takatsu-ku, Kawasaki 213-0012 (Japan); CREST, Japan Science and Technology Agency (JST), 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Department of Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Harayama, Isao; Sekiba, Daiichiro [Tandem Accelerator Complex, University of Tsukuba, Tennodai 1-1-1, Tsukuba, Ibaraki 305-8577 (Japan); Hasegawa, Tetsuya [Kanagawa Academy of Science and Technology (KAST), 3-2-1 Sakado, Takatsu-ku, Kawasaki 213-0012 (Japan); CREST, Japan Science and Technology Agency (JST), 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Department of Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)

    2014-05-30

    InO{sub x}F{sub y} thin films were epitaxially grown on Y-stabilized ZrO{sub 2} (111) substrates by reactive pulsed laser deposition. By changing the substrate temperature (T{sub S}), we were able to control the fluorine content of the film. Phase-pure epitaxial thin films with bixbyite-like ordering in the anion-site occupancy were obtained at high T{sub S} (≥ 240 °C), where fluorine was inserted into the vacancy sites in the bixbyite lattice up to y / (x + y) ∼ 0.3. By decreasing T{sub S}, y / (x + y) increased and the bixbyite-like ordering disappeared; simultaneously, fluorine-rich and fluorine-poor subphases emerged. The films grown at T{sub S} ≤ 150 °C were amorphous and exhibited higher optical absorbance and electrical resistivity than the epitaxial films. - Highlights: • InO{sub x}F{sub y} epitaxial thin films with high fluorine concentration were grown on Y:ZrO{sub 2}. • Anion composition and structural, optical and transport properties were studied. • Fluorine is topotactically inserted into the oxygen vacancy sites in bixbyite cell. • Bixbyite-like ordering of the anion site occupancy was conserved in y / (x + y) ≤ ∼ 0.3.

  2. Epitaxial growth of indium oxyfluoride thin films by reactive pulsed laser deposition: Structural change induced by fluorine insertion into vacancy sites in bixbyite structure

    International Nuclear Information System (INIS)

    Okazaki, Sohei; Hirose, Yasushi; Nakao, Shoichiro; Yang, Chang; Harayama, Isao; Sekiba, Daiichiro; Hasegawa, Tetsuya

    2014-01-01

    InO x F y thin films were epitaxially grown on Y-stabilized ZrO 2 (111) substrates by reactive pulsed laser deposition. By changing the substrate temperature (T S ), we were able to control the fluorine content of the film. Phase-pure epitaxial thin films with bixbyite-like ordering in the anion-site occupancy were obtained at high T S (≥ 240 °C), where fluorine was inserted into the vacancy sites in the bixbyite lattice up to y / (x + y) ∼ 0.3. By decreasing T S , y / (x + y) increased and the bixbyite-like ordering disappeared; simultaneously, fluorine-rich and fluorine-poor subphases emerged. The films grown at T S ≤ 150 °C were amorphous and exhibited higher optical absorbance and electrical resistivity than the epitaxial films. - Highlights: • InO x F y epitaxial thin films with high fluorine concentration were grown on Y:ZrO 2 . • Anion composition and structural, optical and transport properties were studied. • Fluorine is topotactically inserted into the oxygen vacancy sites in bixbyite cell. • Bixbyite-like ordering of the anion site occupancy was conserved in y / (x + y) ≤ ∼ 0.3

  3. Study of temperature dependence and angular distribution of poly(9,9-dioctylfluorene) polymer films deposited by matrix-assisted pulsed laser evaporation (MAPLE)

    International Nuclear Information System (INIS)

    Caricato, A.P.; Anni, M.; Manera, M.G.; Martino, M.; Rella, R.; Romano, F.; Tunno, T.; Valerini, D.

    2009-01-01

    Poly(9,9-dioctylfluorene) (PFO) polymer films were deposited by matrix-assisted pulsed laser evaporation (MAPLE) technique. The polymer was diluted (0.5 wt%) in tetrahydrofuran and, once cooled to liquid nitrogen temperature, it was irradiated with a KrF excimer laser. 10,000 laser pulses were used to deposit PFO films on Si substrates at different temperatures (-16, 30, 50 and 70 deg. C). One PFO film was deposited with 16,000 laser pulses at a substrate temperature of 50 deg. C. The morphology, optical and structural properties of the films were investigated by SEM, AFM, PL and FTIR spectroscopy. SEM inspection showed different characteristic features on the film surface, like deflated balloons, droplets and entangled polymer filaments. The roughness of the films was, at least partially, controlled by substrate heating, which however had the effect to reduce the deposition rate. The increase of the laser pulse number modified the target composition and increased the surface roughness. The angular distribution of the material ejected from the target confirmed the forward ejection of the target material. PFO films presented negligible modification of the chemical structure respect to the bulk material.

  4. Role of Laser Power, Wavelength, and Pulse Duration in Laser Assisted Tin-Induced Crystallization of Amorphous Silicon

    Directory of Open Access Journals (Sweden)

    V. B. Neimash

    2018-01-01

    Full Text Available This work describes tin-induced crystallization of amorphous silicon studied with Raman spectroscopy in thin-film structures Si-Sn-Si irradiated with pulsed laser light. We have found and analyzed dependencies of the nanocrystals’ size and concentration on the laser pulse intensity for 10 ns and 150 μm duration laser pulses at the wavelengths of 535 nm and 1070 nm. Efficient transformation of the amorphous silicon into a crystalline phase during the 10 ns time interval of the acting laser pulse in the 200 nm thickness films of the amorphous silicon was demonstrated. The results were analyzed theoretically by modeling the spatial and temporal distribution of temperature in the amorphous silicon sample within the laser spot location. Simulations confirmed importance of light absorption depth (irradiation wavelength in formation and evolution of the temperature profile that affects the crystallization processes in irradiated structures.

  5. Nonlinear optical studies on 4-(ferrocenylmethylimino)-2-hydroxy-benzoic acid thin films deposited by matrix-assisted pulsed laser evaporation (MAPLE)

    Energy Technology Data Exchange (ETDEWEB)

    Matei, Andreea [INFLPR - National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor Str., Magurele RO-077125, Bucharest (Romania); Marinescu, Maria, E-mail: maria.marinescu@chimie.unibuc.ro [UB - University of Bucharest, Faculty of Chemistry, 90-92 Şoseaua Panduri, Sector 5, RO-010184, Bucharest (Romania); Constantinescu, Catalin, E-mail: catalin.constantinescu@inflpr.ro [INFLPR - National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor Str., Magurele RO-077125, Bucharest (Romania); Ion, Valentin; Mitu, Bogdana [INFLPR - National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor Str., Magurele RO-077125, Bucharest (Romania); Ionita, Iulian [INFLPR - National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor Str., Magurele RO-077125, Bucharest (Romania); UB - University of Bucharest, Faculty of Physics, 405 Atomistilor Str., Magurele RO-077125, Bucharest (Romania); Dinescu, Maria [INFLPR - National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor Str., Magurele RO-077125, Bucharest (Romania); Emandi, Ana [INFLPR - National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor Str., Magurele RO-077125, Bucharest (Romania); UB - University of Bucharest, Faculty of Chemistry, 90-92 Şoseaua Panduri, Sector 5, RO-010184, Bucharest (Romania)

    2016-06-30

    Graphical abstract: - Highlights: • A newly synthesized ferrocene-derivative exhibits SHG potential. • Matrix-assisted pulsed laser evaporation is employed for thin film fabrication. • The optical properties of the films are investigated, presented and discussed. • At maximum laser output power, the SHG signal is strongly influenced by thin film thickness. - Abstract: We present results on a new, laboratory synthesized ferrocene-derivative, i.e. 4-(ferrocenylmethylimino)-2-hydroxy-benzoic acid. Thin films with controlled thickness are deposited by matrix-assisted pulsed laser evaporation (MAPLE), on quartz and silicon substrates, with the aim of evaluating the nonlinear optical properties for potential optoelectronic applications. Dimethyl sulfoxide was used as matrix, with 1% wt. concentration of the guest compound. The frozen target is irradiated by using a Nd:YAG laser (4ω/266 nm, 7 ns pulse duration, 10 Hz repetition rate), at low fluences ranging from 0.1 to 1 J/cm{sup 2}. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) are used to probe the surface morphology of the films. Fourier transform infrared (FTIR) and Raman spectroscopy reveal similar structure of the thin film material when compared to the starting material. The optical properties of the thin films are investigated by spectroscopic-ellipsometry (SE), and the refractive index dependence with respect to temperature is studied. The second harmonic generation (SHG) potential is assessed by using a femtosecond Ti:sapphire laser (800 nm, 60–100 fs pulse duration, 80 MHz repetition rate), at 200 mW maximum output power, revealing that the SHG signal intensity is strongly influenced by the films’ thickness.

  6. Pulsed laser-assisted focused electron-beam-induced etching of titanium with XeF2: enhanced reaction rate and precursor transport.

    Science.gov (United States)

    Noh, J H; Fowlkes, J D; Timilsina, R; Stanford, M G; Lewis, B B; Rack, P D

    2015-02-25

    In order to enhance the etch rate of electron-beam-induced etching, we introduce a laser-assisted focused electron-beam-induced etching (LA-FEBIE) process which is a versatile, direct write nanofabrication method that allows nanoscale patterning and editing. The results demonstrate that the titanium electron stimulated etch rate via the XeF2 precursor can be enhanced up to a factor of 6 times with an intermittent pulsed laser assist. The evolution of the etching process is correlated to in situ stage current measurements and scanning electron micrographs as a function of time. The increased etch rate is attributed to photothermally enhanced Ti-F reaction and TiF4 desorption and in some regimes enhanced XeF2 surface diffusion to the reaction zone.

  7. Selective Oxidation and Reactive Wetting During Hot-Dip Galvanizing of a 1.0 pct Al-0.5 pct Si TRIP-Assisted Steel

    Science.gov (United States)

    Bellhouse, E. M.; McDermid, J. R.

    2012-07-01

    Selective oxidation and reactive wetting during continuous galvanizing were studied for a low-alloy transformation induced plasticity (TRIP)-assisted steel with 0.2 pct C, 1.5 pct Mn, 1.0 pct Al and 0.5 pct Si. Three process atmospheres were tested during annealing prior to galvanizing: 220 K (-53 °C) dew point (dp) N2-20 pct H2, 243 K (-30 °C) dp N2-5 pct H2 and 278 K (+5 °C) dp N2-5 pct H2. The process atmosphere oxygen partial pressure affected the oxide chemistry, morphology and thickness. For the 220 K (-53 °C) dp and 243 K (-30 °C) dp process atmospheres, film and nodule-type manganese, silicon and aluminum containing oxides were observed at the surface. For the 278 K (+5 °C) dp atmosphere, MnO was observed at the grain boundaries and as thicker localized surface films. Oxide morphology, thickness and chemistry affected reactive wetting, with complete wetting being observed for the 220 K (-53 °C) dp and 243 K (-30 °C) dp process atmospheres and incomplete reactive wetting being observed for the 278 K (+5 °C) dp atmosphere. Complete reactive wetting for the 220 K (-53 °C) dp and 243 K (-30 °C) dp process atmospheres was attributed to a combination of zinc bridging of oxides, aluminothermic reduction of surface oxides and wetting of the oxides. Incomplete wetting for the 278 K (+5 °C) dp atmosphere was attributed to localized thick MnO films.

  8. Organic Thin Films Deposited by Emulsion-Based, Resonant Infrared, Matrix-Assisted Pulsed Laser Evaporation: Fundamentals and Applications

    Science.gov (United States)

    Ge, Wangyao

    Thin film deposition techniques are indispensable to the development of modern technologies as thin film based optical coatings, optoelectronic devices, sensors, and biological implants are the building blocks of many complicated technologies, and their performance heavily depends on the applied deposition technique. Particularly, the emergence of novel solution-processed materials, such as soft organic molecules, inorganic compounds and colloidal nanoparticles, facilitates the development of flexible and printed electronics that are inexpensive, light weight, green and smart, and these thin film devices represent future trends for new technologies. One appealing feature of solution-processed materials is that they can be deposited into thin films using solution-processed deposition techniques that are straightforward, inexpensive, high throughput and advantageous to industrialize thin film based devices. However, solution-processed techniques rely on wet deposition, which has limitations in certain applications, such as multi-layered film deposition of similar materials and blended film deposition of dissimilar materials. These limitations cannot be addressed by traditional, vacuum-based deposition techniques because these dry approaches are often too energetic and can degrade soft materials, such as polymers, such that the performance of resulting thin film based devices is compromised. The work presented in this dissertation explores a novel thin film deposition technique, namely emulsion-based, resonant infrared, matrix-assisted pulsed laser evaporation (RIR-MAPLE), which combines characteristics of wet and dry deposition techniques for solution-processed materials. Previous studies have demonstrated the feasibility of emulsion-based RIR-MAPLE to deposit uniform and continuous organic, nanoparticle and blended films, as well as hetero-structures that otherwise are difficult to achieve. However, fundamental understanding of the growth mechanisms that govern

  9. The relationship of chronic and momentary work stress to cardiac reactivity in female managers: feasibility of a smart phone-assisted assessment system.

    Science.gov (United States)

    Lumley, Mark A; Shi, Weisong; Wiholm, Clairy; Slatcher, Richard B; Sandmark, Helene; Wang, Shinan; Hytter, Anders; Arnetz, Bengt B

    2014-09-01

    To evaluate a wireless smart phone-assisted (SPA) system that assesses ongoing heart rate (HR) and HR-triggered participant reports of momentary stress when HR is elevated during daily life. This SPA system was used to determine the independent and interactive roles of chronic and momentary work stress on HR reactivity among female managers. A sample of 40 female managers reported their chronic work stress and wore the SPA system during a regular workday. They provided multiple reports of their momentary stress, both when triggered by increased HR and at random times. Relationships among chronic stress, momentary stress, and HR were analyzed with hierarchical linear modeling. Both chronic work stress (b = 0.08, standard error [SE] = 0.03, p = .003) and momentary work stress (b = 1.25, SE = 0.62, p = .052) independently predicted greater HR reactivity, adjusting for baseline HR, age, smoking, caffeine, alcohol use, and momentary physical activity levels. More importantly, chronic and momentary stress significantly interacted (b = 1.00, SE = 0.04, p = .036); high momentary stress predicted elevated HR only in the context of high chronic stress. Female managers who experience chronic work stress displayed elevated cardiac reactivity during momentary stress at work. The joint assessment of chronic stress and momentary stress and their relationship to physiological functioning during work clarifies the potential health risks associated with work stress. Moreover, this wireless SPA system captures the immediate subjective context of individuals when physiological arousal occurs, which may lead to tailored stress management programs in the workplace.

  10. Computer Color Matching and Levelness of PEG-Based Reverse Micellar Decamethyl cyclopentasiloxane (D5 Solvent-Assisted Reactive Dyeing on Cotton Fiber

    Directory of Open Access Journals (Sweden)

    Alan Y. L. Tang

    2017-07-01

    Full Text Available The color matching and levelness of cotton fabrics dyed with reactive dye, in a non-aqueous environmentally-friendly medium of decamethylcyclopentasiloxane (D5, was investigated using the non-ionic surfactant reverse-micellar approach comprised of poly(ethylene glycol-based surfactant. The calibration dyeing databases for both conventional water-based dyeing and D5-assisted reverse micellar dyeing were established, along with the dyeing of standard samples with predetermined concentrations. Computer color matching (CCM was conducted by using different color difference formulae for both dyeing methods. Experimental results reveal that the measured concentrations were nearly the same as the expected concentrations for both methods. This indicates that the D5-assisted non-ionic reverse micellar dyeing approach can achieve color matching as good as the conventional dyeing system. The levelness of the dyed samples was measured according to the relative unlevelness indices (RUI, and the results reveal that the samples dyed by the D5 reverse micellar dyeing system can achieve good to excellent levelness comparable to that of the conventional dyeing system.

  11. Surfactant-assisted direct biodiesel production from wet Nannochloropsis occulata by in situ transesterification/reactive extraction

    Directory of Open Access Journals (Sweden)

    Kamoru A. Salam

    2016-03-01

    Full Text Available This article reports an in situ transesterification/reactive extraction of Nannochloropsis occulata for fatty acid methyl ester (FAME production using H2SO4, sodium dodecyl sulphate (SDS plus H2SO4 and zirconium dodecyl sulphate (ZDS. A maximum 67 % FAME yield was produced by ZDS. Effect of inclusion of sodium dodecyl sulphate (SDS in H2SO4 for FAME enhancement and water tolerance was also studied by hydrating the algae with 10 % - 30 % distilled water (w/w dry algae. Treatment with SDS in H2SO4 increases the FAME production rate and water tolerance of the process. Inclusion of SDS in H2SO4 produced a maximum 98.3 % FAME yield at 20 % moisture in the algae. The FAME concentration began to diminish only at 30 % moisture in the algae. Furthermore, the presence of a small amount of water in the biomass or methanol increased the lipid extraction efficiency, improving the FAME yield, rather than inhibiting the reaction.

  12. Kinetic and mechanistic studies of reactive intermediates in photochemical and transition metal-assisted oxidation, decarboxylation and alkyl transfer reactions

    Science.gov (United States)

    Carraher, Jack McCaslin

    Reactive species like high-valent metal-oxo complexes and carbon and oxygen centered radicals are important intermediates in enzymatic systems, atmospheric chemistry, and industrial processes. Understanding the pathways by which these intermediates form, their relative reactivity, and their fate after reactions is of the utmost importance. Herein are described the mechanistic detail for the generation of several reactive intermediates, synthesis of precursors, characterization of precursors, and methods to direct the chemistry to more desirable outcomes yielding 'greener' sources of commodity chemicals and fuels. High-valent Chromium from Hydroperoxido-Chromium(III). The decomposition of pentaaquahydroperoxido chromium(III) ion (hereafter Cr aqOOH2+) in acidic aqueous solutions is kinetically complex and generates mixtures of products (Craq3+, HCrO 4-, H2O2, and O2). The yield of high-valent chromium products (known carcinogens) increased from a few percent at pH 1 to 70 % at pH 5.5 (near biological pH). Yields of H 2O2 increased with acid concentration. The reproducibility of the kinetic data was poor, but became simplified in the presence of H2O2 or 2,2‧-azinobis(3-ethylbenzothiazoline-6-sulfonate) dianion (ABTS2-). Both are capable of scavenging strongly oxidizing intermediates). The observed rate constants (pH 1, [O2] ≤ 0.03 mM) in the presence of these scavengers are independent of [scavenger] and within the error are the same (k,ABTS2- = (4.9 +/- 0.2) x 10-4 s-1 and kH2O2 = (5.3 +/- 0.7) x 10-4 s-1); indicating involvement of the scavengers in post-rate determining steps. In the presence of either scavenger, decomposition of CrOOH2+ obeyed a two-term rate law, k obs / s-1 = (6.7 +/- 0.7) x 10-4 + (7.6 +/- 1.1) x 10-4 [H+]. Effect of [H+] on the kinetics and the product distribution, cleaner kinetics in the presence of scavengers, and independence of kobs on [scavenger] suggest a dual-pathway mechanism for the decay of Craq OOH2+. The H+-catalyzed path

  13. Films of brookite TiO2 nanorods/nanoparticles deposited by matrix-assisted pulsed laser evaporation as NO2 gas-sensing layers

    Science.gov (United States)

    Caricato, A. P.; Buonsanti, R.; Catalano, M.; Cesaria, M.; Cozzoli, P. D.; Luches, A.; Manera, M. G.; Martino, M.; Taurino, A.; Rella, R.

    2011-09-01

    Titanium dioxide (TiO2) nanorods in the brookite phase, with average dimensions of 3-4 nm × 20-50 nm, were synthesized by a wet-chemical aminolysis route and used as precursors for thin films that were deposited by the matrix-assisted pulsed laser evaporation (MAPLE) technique. A nanorod solution in toluene (0.016 wt% TiO2) was frozen at the liquid-nitrogen temperature and irradiated with a KrF excimer laser at a fluence of 350 mJ/cm2 and repetition rate of 10 Hz. Single-crystal Si wafers, silica slides, carbon-coated Cu grids and alumina interdigitated slabs were used as substrates to allow performing different characterizations. Films fabricated with 6000 laser pulses had an average thickness of ˜150 nm, and a complete coverage of the selected substrate as achieved. High-resolution scanning and transmission electron microscopy investigations evidenced the formation of quite rough films incorporating individually distinguishable TiO2 nanorods and crystalline spherical nanoparticles with an average diameter of ˜13 nm. Spectrophotometric analysis showed high transparency through the UV-Vis spectral range. Promising resistive sensing responses to 1 ppm of NO2 mixed in dry air were obtained.

  14. Films of brookite TiO{sub 2} nanorods/nanoparticles deposited by matrix-assisted pulsed laser evaporation as NO{sub 2} gas-sensing layers

    Energy Technology Data Exchange (ETDEWEB)

    Caricato, A.P.; Cesaria, M.; Luches, A.; Martino, M. [University of Salento, Department of Physics, Lecce (Italy); Buonsanti, R. [Istituto di Nanoscienze del CNR, National Nanotechnology Laboratory (NNL), Lecce (Italy); Catalano, M.; Manera, M.G.; Taurino, A.; Rella, R. [IMM-CNR, Institute for Microelectronics and Microsystems, Lecce (Italy); Cozzoli, P.D. [Istituto di Nanoscienze del CNR, National Nanotechnology Laboratory (NNL), Lecce (Italy); University of Salento, Department of Innovation Engineering, Lecce (Italy)

    2011-09-15

    Titanium dioxide (TiO{sub 2}) nanorods in the brookite phase, with average dimensions of 3-4 nm x 20-50 nm, were synthesized by a wet-chemical aminolysis route and used as precursors for thin films that were deposited by the matrix-assisted pulsed laser evaporation (MAPLE) technique. A nanorod solution in toluene (0.016 wt% TiO{sub 2}) was frozen at the liquid-nitrogen temperature and irradiated with a KrF excimer laser at a fluence of 350 mJ/cm{sup 2} and repetition rate of 10 Hz. Single-crystal Si wafers, silica slides, carbon-coated Cu grids and alumina interdigitated slabs were used as substrates to allow performing different characterizations. Films fabricated with 6000 laser pulses had an average thickness of {proportional_to}150 nm, and a complete coverage of the selected substrate as achieved. High-resolution scanning and transmission electron microscopy investigations evidenced the formation of quite rough films incorporating individually distinguishable TiO{sub 2} nanorods and crystalline spherical nanoparticles with an average diameter of {proportional_to}13 nm. Spectrophotometric analysis showed high transparency through the UV-Vis spectral range. Promising resistive sensing responses to 1 ppm of NO{sub 2} mixed in dry air were obtained. (orig.)

  15. Studies on the cross-magnetron effect in the reactive indium tin oxide deposition. Effects of an inhomogeneous plasma distribution on the coating properties in dynamic and static coating by means of a pulsed dual magnetron

    International Nuclear Information System (INIS)

    Kleinhempel, Ronny

    2008-01-01

    In the present thesis the reactive ITO deposition process under application of metallic In:Sn targets is intensively studied. The coating deposition pursues at a symmetric bipolarly pulsed dual magnetron both on resting and moving substrates. The thesis comprehends two partial fields. On the one hand the dynamic deposition process was comprehensively characterized at an near-industry test facility and successfully transformed by means of its physical parameters to an industrial coating facility. On the other hand static depositions were performed. These allow the analysis of the lateral distribution of the functional coating properties. By this a correlation to the lateral distributions of the measured plasma parameters could be elaborated [de

  16. Reactivity of Surface Nitrates in H2-Assisted SCR of NOx Over Ag/Al2O3 Catalyst

    DEFF Research Database (Denmark)

    Sadokhina, N. A.; Doronkin, Dmitry E.; Baeva, G. N.

    2013-01-01

    The role of nitrate ad-species in H2-assisted SCR over Ag/Al2O3 was compared in NH3-SCR and n-C6H14-SCR processes. It was found that nitrates could be reduced by NH3 or n-C6H14 at similar rates with H2 co-feeding which indicates a common rate-limiting step. However, contributions of surface nitrate...... reduction to the overall NH3-SCR or n-C6H14-SCR are different as revealed by comparing the rates of nitrate reduction with the rates of steady-state processes. The rate of the steady-state n-C6H14-SCR is virtually identical to the rate of surface nitrate reduction suggesting a significant contribution...... of the surface nitrates reduction to the overall n-C6H14-SCR process. On the other hand, the steady-state rate of NH3-SCR is by ~15 times higher, which indicates that the reduction of surface nitrates plays a marginal role in the overall NH3-SCR....

  17. Binary solvent extraction system and extraction time effects on phenolic antioxidants from kenaf seeds (Hibiscus cannabinus L.) extracted by a pulsed ultrasonic-assisted extraction.

    Science.gov (United States)

    Wong, Yu Hua; Lau, Hwee Wen; Tan, Chin Ping; Long, Kamariah; Nyam, Kar Lin

    2014-01-01

    The aim of this study was to determine the best parameter for extracting phenolic-enriched kenaf (Hibiscus cannabinus L.) seeds by a pulsed ultrasonic-assisted extraction. The antioxidant activities of ultrasonic-assisted kenaf seed extracts (KSE) were determined by a 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity assay, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging assay, β -carotene bleaching inhibition assay, and ferric reducing antioxidant power (FRAP) assay. Total phenolic content (TPC) and total flavonoid content (TFC) evaluations were carried out to determine the phenolic and flavonoid contents in KSE. The KSE from the best extraction parameter was then subjected to high performance liquid chromatography (HPLC) to quantify the phenolic compounds. The optimised extraction condition employed 80% ethanol for 15 min, with the highest values determined for the DPPH, ABTS, and FRAP assay. KSE contained mainly tannic acid (2302.20 mg/100 g extract) and sinapic acid (1198.22 mg/100 g extract), which can be used as alternative antioxidants in the food industry.

  18. Binary Solvent Extraction System and Extraction Time Effects on Phenolic Antioxidants from Kenaf Seeds (Hibiscus cannabinus L.) Extracted by a Pulsed Ultrasonic-Assisted Extraction

    Science.gov (United States)

    Lau, Hwee Wen; Nyam, Kar Lin

    2014-01-01

    The aim of this study was to determine the best parameter for extracting phenolic-enriched kenaf (Hibiscus cannabinus L.) seeds by a pulsed ultrasonic-assisted extraction. The antioxidant activities of ultrasonic-assisted kenaf seed extracts (KSE) were determined by a 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity assay, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging assay, β-carotene bleaching inhibition assay, and ferric reducing antioxidant power (FRAP) assay. Total phenolic content (TPC) and total flavonoid content (TFC) evaluations were carried out to determine the phenolic and flavonoid contents in KSE. The KSE from the best extraction parameter was then subjected to high performance liquid chromatography (HPLC) to quantify the phenolic compounds. The optimised extraction condition employed 80% ethanol for 15 min, with the highest values determined for the DPPH, ABTS, and FRAP assay. KSE contained mainly tannic acid (2302.20 mg/100 g extract) and sinapic acid (1198.22 mg/100 g extract), which can be used as alternative antioxidants in the food industry. PMID:24592184

  19. Binary Solvent Extraction System and Extraction Time Effects on Phenolic Antioxidants from Kenaf Seeds (Hibiscus cannabinus L. Extracted by a Pulsed Ultrasonic-Assisted Extraction

    Directory of Open Access Journals (Sweden)

    Yu Hua Wong

    2014-01-01

    Full Text Available The aim of this study was to determine the best parameter for extracting phenolic-enriched kenaf (Hibiscus cannabinus L. seeds by a pulsed ultrasonic-assisted extraction. The antioxidant activities of ultrasonic-assisted kenaf seed extracts (KSE were determined by a 2,2-diphenyl-1-picrylhydrazyl (DPPH radical scavenging capacity assay, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS radical scavenging assay, β-carotene bleaching inhibition assay, and ferric reducing antioxidant power (FRAP assay. Total phenolic content (TPC and total flavonoid content (TFC evaluations were carried out to determine the phenolic and flavonoid contents in KSE. The KSE from the best extraction parameter was then subjected to high performance liquid chromatography (HPLC to quantify the phenolic compounds. The optimised extraction condition employed 80% ethanol for 15 min, with the highest values determined for the DPPH, ABTS, and FRAP assay. KSE contained mainly tannic acid (2302.20 mg/100 g extract and sinapic acid (1198.22 mg/100 g extract, which can be used as alternative antioxidants in the food industry.

  20. Resonance hairpin and Langmuir probe-assisted laser photodetachment measurements of the negative ion density in a pulsed dc magnetron discharge

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, James W.; Dodd, Robert; You, S.-D.; Sirse, Nishant; Karkari, Shantanu Kumar [Department of Electrical Engineering and Electronics, University of Liverpool, Liverpool (United Kingdom); National Centre for Plasma Science and Technology, Dublin City University, Dublin 9, Republic of Ireland (Ireland); National Centre for Plasma Science and Technology, Dublin City University, Dublin 9, Republic of Ireland and Institute for Plasma Research, Bhat Gandhinagar, Gujarat (India)

    2011-05-15

    The time-resolved negative oxygen ion density n{sub -} close to the center line in a reactive pulsed dc magnetron discharge (10 kHz and 50% duty cycle) has been determined for the first time using a combination of laser photodetachment and resonance hairpin probing. The discharge was operated at a power of 50 W in 70% argon and 30% oxygen gas mixtures at 1.3 Pa pressure. The results show that the O{sup -} density remains pretty constant during the driven phase of the discharge at values typically below 5x10{sup 14} m{sup -3}; however, in the off-time, the O{sup -} density grows reaching values several times those in the on-time. This leads to the negative ion fraction (or degree of electronegativity) {alpha}=n{sub -}/n{sub e} being higher in the off phase (maximum value {alpha}{approx}1) than in the on phase ({alpha}=0.05-0.3). The authors also see higher values of {alpha} at positions close to the magnetic null than in the more magnetized region of the plasma. This fractional increase in negative ion density during the off-phase is attributed to the enhanced dissociative electron attachment of highly excited oxygen molecules in the cooling plasma. The results show that close to the magnetic null the photodetached electron density decays quickly after the laser pulse, followed by a slow decay over a few microseconds governed by the negative ion temperature. However, in the magnetized regions of the plasma, this decay is more gradual. This is attributed to the different cross-field transport rates for electrons in these two regions. The resonance hairpin probe measurements of the photoelectron densities are compared directly to photoelectron currents obtained using a conventional Langmuir probe. There is good agreement in the general trends, particularly in the off-time.

  1. Low-loss interference filter arrays made by plasma-assisted reactive magnetron sputtering (PARMS) for high-performance multispectral imaging

    Science.gov (United States)

    Broßmann, Jan; Best, Thorsten; Bauer, Thomas; Jakobs, Stefan; Eisenhammer, Thomas

    2016-10-01

    Optical remote sensing of the earth from air and space typically utilizes several channels in the visible and near infrared spectrum. Thin-film optical interference filters, mostly of narrow bandpass type, are applied to select these channels. The filters are arranged in filter wheels, arrays of discrete stripe filters mounted in frames, or patterned arrays on a monolithic substrate. Such multi-channel filter assemblies can be mounted close to the detector, which allows a compact and lightweight camera design. Recent progress in image resolution and sensor sensitivity requires improvements of the optical filter performance. Higher demands placed on blocking in the UV and NIR and in between the spectral channels, in-band transmission and filter edge steepness as well as scattering lead to more complex filter coatings with thicknesses in the range of 10 - 25μm. Technological limits of the conventionally used ion-assisted evaporation process (IAD) can be overcome only by more precise and higher-energetic coating technologies like plasma-assisted reactive magnetron sputtering (PARMS) in combination with optical broadband monitoring. Optics Balzers has developed a photolithographic patterning process for coating thicknesses up to 15μm that is fully compatible with the advanced PARMS coating technology. This provides the possibility of depositing multiple complex high-performance filters on a monolithic substrate. We present an overview of the performance of recently developed filters with improved spectral performance designed for both monolithic filter-arrays and stripe filters mounted in frames. The pros and cons as well as the resulting limits of the filter designs for both configurations are discussed.

  2. Physical model of reactor pulse

    International Nuclear Information System (INIS)

    Petrovic, A.; Ravnik, M.

    2004-01-01

    Pulse experiments have been performed at J. Stefan Institute TRIGA reactor since 1991. In total, more than 130 pulses have been performed. Extensive experimental information on the pulse physical characteristics has been accumulated. Fuchs-Hansen adiabatic model has been used for predicting and analysing the pulse parameters. The model is based on point kinetics equation, neglecting the delayed neutrons and assuming constant inserted reactivity in form of step function. Deficiencies of the Fuchs-Hansen model and systematic experimental errors have been observed and analysed. Recently, the pulse model was improved by including the delayed neutrons and time dependence of inserted reactivity. The results explain the observed non-linearity of the pulse energy for high pulses due to finite time of pulse rod withdrawal and the contribution of the delayed neutrons after the prompt part of the pulse. The results of the improved model are in good agreement with experimental results. (author)

  3. OPTIMIZATION OF PATCHOULI OIL (POGOSTEMON CABLIN, BENTH WITH STEAM DISTILLATION ASSISTED BY PULSED ELECTRIC FIELD VIA RESPONSE SURFACE METHODOLOGY

    Directory of Open Access Journals (Sweden)

    SUKARDI

    2017-08-01

    Full Text Available The study was aimed to determine the role of pulsed electric field (PEF treatment before hydro-distillation of the patchouli oil. Response Surface Methodology (RSM was employed to optimize PEF treatment (voltages, frequencies and times of distillation of patchouli oil from dried patchouli crops. The experimental design and analysis the result to obtain the optimal processing parameters was a Box-Behnken Design (BBD. Three variables were examined in this study: voltages (1,000-2,000 volt; frequencies (1,000-2,000 Hz; and distillation time (4-8 hours. The results showed that the voltage greatly affects the volume of patchouli oil obtained and optimum condition of PEF was voltages of 2,000 volts, frequencies of 1,874 Hz, and 8 hours distillation. The patchouli oil obtained is 8.037 ml of 300 g of dry material (±2.7%. The verification of the model shows that 96.6% (7.76±0.15 ml can adequately for reflecting the expected optimization.

  4. Pulsed ion-beam assisted deposition of Ge nanocrystals on SiO2 for non-volatile memory device

    International Nuclear Information System (INIS)

    Stepina, N.P.; Dvurechenskii, A.V.; Armbrister, V.A.; Kirienko, V.V.; Novikov, P.L.; Kesler, V.G.; Gutakovskii, A.K.; Smagina, Z.V.; Spesivtzev, E.V.

    2008-01-01

    A floating gate memory structure, utilizing Ge nanocrystals (NCs) deposited on tunnel SiO 2 , have been fabricated using pulsed low energy ion-beam induced molecular-beam deposition (MBD) in ultra-high vacuum. The ion-beam action is shown to stimulate the nucleation of Ge NCs when being applied after thin Ge layer deposition. Growth conditions for independent change of NCs size and array density were established allowing to optimize the structure parameters required for memory device. Activation energy E = 0.25 eV was determined from the temperature dependence of NCs array density. Monte Carlo simulation has shown that the process, determining NCs array density, is the surface diffusion. Embedding of the crystalline Ge dots into silicon oxide was carried out by selective oxidation of Si(100)/SiO 2 /Ge(NCs)/poly-Si structure. MOS-capacitor obtained after oxidation showed a hysteresis in its C-V curves attributed to charge retention in the Ge dots

  5. TiO2 nanoparticle thin film deposition by matrix assisted pulsed laser evaporation for sensing applications

    International Nuclear Information System (INIS)

    Caricato, A.P.; Capone, S.; Ciccarella, G.; Martino, M.; Rella, R.; Romano, F.; Spadavecchia, J.; Taurino, A.; Tunno, T.; Valerini, D.

    2007-01-01

    The MAPLE technique has been used for the deposition of nanostructured titania (TiO 2 ) nanoparticles thin films to be used for gas sensors applications. An aqueous solution of TiO 2 nanoparticles, synthesised by a novel chemical route, was frozen at liquid nitrogen temperature and irradiated with a pulsed ArF excimer laser in a vacuum chamber. A uniform distribution of TiO 2 nanoparticles with an average size of about 10 nm was deposited on Si and interdigitated Al 2 O 3 substrates as demonstrated by high resolution scanning electron microscopy-field emission gun inspection (SEM-FEG). Energy dispersive X-ray (EDX) analysis revealed the presence of only the titanium and oxygen signals and FTIR (Fourier transform infra-red) revealed the TiO 2 characteristic composition and bond. A comparison with a spin coated thin film obtained from the same solution of TiO 2 nanoparticles is reported. The sensing properties of the films deposited on interdigitated substrates were investigated, too

  6. Development of a non-thermal accelerated pulsed UV photolysis assisted digestion method for fresh and dried food samples

    International Nuclear Information System (INIS)

    Solis, C.; Lagunas-Solar, M.C.; Perley, B.P.; Pina, C.; Aguilar, L.F.; Flocchini, R.G.

    2002-01-01

    A simple, fast digestion procedure for fresh and dried foods, using high-power pulsed UV photolysis in the presence of hydrogen peroxide, is being developed. The homogenized food samples were mixed with H 2 O 2 or with a mixture of H 2 O 2 and HNO 3 , and irradiated for short times with a 248-nm UV excimer laser. After centrifugation, a clear, colorless solution was obtained and aliquots were deposited on Teflon filters for XRF and/or PIXE analyses. Standard reference materials (NIST Peach Leaves; Typical Diet) were also analyzed to compare recoveries and detection limits. Improvements in detection limits were observed, but a few trace elements (<1 ppm) were not reproducibly detected (Fe, Sr). This method proved to be practical for the accelerated digestion of food samples and preparing analytes in short-time intervals. In combination with PIXE and XRF, it allows high-sensitivity multi-elemental analyses for screening the nutritional elements and for food safety purposes regarding the potential presence of toxic elements. Further development to optimize and validate this procedure for a broader range of analytes is in progress

  7. Olive oil pilot-production assisted by pulsed electric field: impact on extraction yield, chemical parameters and sensory properties.

    Science.gov (United States)

    Puértolas, Eduardo; Martínez de Marañón, Iñigo

    2015-01-15

    The impact of the use of pulsed electric field (PEF) technology on Arroniz olive oil production in terms of extraction yield and chemical and sensory quality has been studied at pilot scale in an industrial oil mill. The application of a PEF treatment (2 kV/cm; 11.25 kJ/kg) to the olive paste significantly increased the extraction yield by 13.3%, with respect to a control. Furthermore, olive oil obtained by PEF showed total phenolic content, total phytosterols and total tocopherols significantly higher than control (11.5%, 9.9% and 15.0%, respectively). The use of PEF had no negative effects on general chemical and sensory characteristics of the olive oil, maintaining the highest quality according to EU legal standards (EVOO; extra virgin olive oil). Therefore, PEF could be an appropriate technology to improve olive oil yield and produce EVOO enriched in human-health-related compounds, such as polyphenols, phytosterols and tocopherols. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Microwave-assisted reactive sintering and lithium ion conductivity of Li1.3Al0.3Ti1.7(PO4)3 solid electrolyte

    Science.gov (United States)

    Hallopeau, Leopold; Bregiroux, Damien; Rousse, Gwenaëlle; Portehault, David; Stevens, Philippe; Toussaint, Gwenaëlle; Laberty-Robert, Christel

    2018-02-01

    Li1.3Al0.3Ti1.7(PO4)3 (LATP) materials are made of a three-dimensional framework of TiO6 octahedra and PO4 tetrahedra, which provides several positions for Li+ ions. The resulting high ionic conductivity is promising to yield electrolytes for all-solid-state Li-ion batteries. In order to elaborate dense ceramics, conventional sintering methods often use high temperature (≥1000 °C) with long dwelling times (several hours) to achieve high relative density (∼90%). In this work, an innovative synthesis and processing approach is proposed. A fast and easy processing technique called microwave-assisted reactive sintering is used to both synthesize and sinter LATP ceramics with suitable properties in one single step. Pure and crystalline LATP ceramics can be achieved in only 10 min at 890 °C starting from amorphous, compacted LATP's precursors powders. Despite a relative density of 88%, the ionic conductivity measured at ambient temperature (3.15 × 10-4 S cm-1) is among the best reported so far. The study of the activation energy for Li+ conduction confirms the high quality of the ceramic (purity and crystallinity) achieved by using this new approach, thus emphasizing its interest for making ion-conducting ceramics in a simple and fast way.

  9. Biocompatible Au@Carbynoid/Pluronic-F127 nanocomposites synthesized by pulsed laser ablation assisted CO2 recycling

    Science.gov (United States)

    Del Rosso, T.; Louro, S. R. W.; Deepak, F. L.; Romani, E. C.; Zaman, Q.; Tahir; Pandoli, O.; Cremona, M.; Freire Junior, F. L.; De Beule, P. A. A.; De St. Pierre, T.; Aucelio, R. Q.; Mariotto, G.; Gemini-Piperni, S.; Ribeiro, A. R.; Landi, S. M.; Magalhães, A.

    2018-05-01

    Ligand-free carbynoid-encapsulated gold nanocomposites (Au@Carbynoid NCs) with blue-shifted localized surface plasmon resonance (LSPR) have been synthesized by CO2 recycling induced by pulsed laser ablation (PLA) of a solid gold target in aqueous solution with NaOH at pH 7.0. High Resolution Transmission Electron Microscopy (HRTEM) images at not destructive acceleration voltage of 80 kV revealed carbynoid nanocrystals around the gold core, associated to the intense bond length alternation (BLA) Raman mode of the carbon atomic wires (CAWs), centered at 2124 cm-1, observed in the Surface Enhanced Raman Scattering (SERS) spectra. It was verified that interlinking process with sp to sp2 conversion of the CAWs is induced both by high acceleration voltage in HRTEM and high irradiance of the excitation beam used in SERS measurements. Post synthesis mixing of Pluronic-F127 copolymer with pre-synthesized Au@Carbynoid NCs allows the formation of a fully biocompatible colloidal solution of Au@Carbynoid/Copolymer NCs. SERS investigation highlights that the Raman band of the BLA mode can be used as efficient Raman tag to monitor the functionalization of the NCs with the copolymer. The biocompatibility of the NCs was demonstrated performing a study of cytotoxicity using human skin fibroblasts. As proof of principle, it was demonstrated that the photodynamic activity of the bifunctional Au@Carbynoid/PF127 NCs in the presence of chlorin e6 (Ce6) drug can be enhanced inducing the aggregation state of the colloidal suspension. The stability of the colloidal dispersions of Au@Carbynoid NCs functionalized with Pluronic-F127 is verified after centrifugation in PBS (0.15 mol L-1 NaCl) solutions, confirming the possibility to use the green carbynoid based NCs as drug-carrier in biological applications.

  10. Crystalline phase control and growth selectivity of β-MnO{sub 2} thin films by remote plasma assisted pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Abi-Akl, M.; Tabbal, M., E-mail: malek.tabbal@aub.edu.lb; Kassem, W.

    2016-08-01

    In this paper, we exploit the effect of coupling an oxygen remote plasma source to Pulsed Laser Deposition (PLD) for the growth of pure and well crystallized β-MnO{sub 2} films. Films were grown on Si substrates by laser ablation of a MnO target in oxygen ambient and remote plasma. X-Ray Diffraction, Fourier Transform Infra-Red spectroscopy and Raman scattering were used to determine the crystalline structure and bonding in the grown layers, whereas Atomic Force Microscopy was used to study their morphology and surface roughness. Deposition at 500 °C and high oxygen pressure (33.3–66.6 Pa) resulted in the formation of films with roughness of 12 nm consisting of nsutite γ-MnO{sub 2}, a structure characterized by the intergrowth of the pyrolusite β-MnO{sub 2} in a ramsdellite R-MnO{sub 2} matrix. Deposition at the same temperature but low pressure (1.33–3.33 Pa) in oxygen ambient lead to the formation of Mn{sub 2}O{sub 3} whereas plasma activation within the same pressure range induced the growth of single phase highly crystalline β-MnO{sub 2} having smooth surfaces with a roughness value of 0.6 nm. Such results underline the capability of remote plasma assisted PLD in selecting and controlling the crystalline phase of manganese oxide layers. - Highlights: • MnO{sub 2} films were grown by Remote Plasma Assisted Pulsed Laser Deposition. • Crystalline MnO{sub 2} is formed at a substrate temperature of 500 °C. • Smooth crystalline single phase β-MnO{sub 2} films were obtained at 1.33–3.33 Pa. • Deposition at 1.33–3.33 Pa without plasma activation lead to the growth of Mn{sub 2}O{sub 3}. • Without plasma, mixed phases of MnO{sub 2} polymorphs are obtained at 33.3 Pa and above.

  11. Biocompatibility assessment of graphene oxide-hydroxyapatite coating applied on TiO2 nanotubes by ultrasound-assisted pulse electrodeposition.

    Science.gov (United States)

    Fathyunes, Leila; Khalil-Allafi, Jafar; Sheykholeslami, Seyed Omid Reza; Moosavifar, Maryam

    2018-06-01

    In this study, the ultrasound-assisted pulse electrodeposition was introduced to fabricate the graphene oxide (GO)-hydroxyapatite (HA) coating on TiO 2 nanotubes. The results of the X-ray diffraction (XRD), Fourier Transform Infrared spectroscope (FTIR), Transmission Electron Microscope (TEM) and micro-Raman spectroscopy showed the successful synthesis of GO. The Scanning Electron Microscope (SEM) images revealed that in the presence of ultrasonic waves and GO sheets a more compact HA-based coating with refined microstructure could be formed on the pretreated titanium. The results of micro-Raman analysis confirmed the successful incorporation of the reinforcement filler of GO into the coating electrodeposited by the ultrasound-assisted method. The FTIR analysis showed that the GO-HA coating was consisted predominantly of the B-type carbonated HA (CHA) phase. The pretreatment of the substrate and incorporation of the GO sheets into the HA coating had a significant effect on improving the bonding strength at the coating-substrate interface. Moreover, the results of the fibroblast cell culture and 3‑(4,5‑dimethylthiazolyl‑2)‑2, 5‑diphenyltetrazolium bromide (MTT) assay after 2 days demonstrated a higher percentage of cell activity for the GO-HA coated sample. Finally, the 7-day exposure to simulated body fluid (SBF) showed a faster rate of apatite precipitation on the GO-HA coating, as compared to the HA coating and pretreated titanium. Copyright © 2018 Elsevier B.V. All rights reserved.

  12. Photoelectrochemical behavior of Al{sub x}In{sub 1−x}N thin films grown by plasma-assisted dual source reactive evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Alizadeh, M., E-mail: alizadeh_kozerash@yahoo.com; Ganesh, V.; Pandikumar, A.; Goh, B.T.; Azianty, S.; Huang, N.M.; Rahman, S.A., E-mail: saadah@um.edu.my

    2016-06-15

    In this work the dependence of photoelectrochemical (PEC) behavior of Al{sub x}In{sub 1−x}N (0.48 ≤x ≤ 0.66) thin films grown by plasma-assisted dual source reactive evaporation, on the plasma dynamics and the alloys properties was studied. The influence of nitrogen flow rate on the compositional, morphological, structural and optical properties of the as-prepared films were investigated using X-ray photoelectron spectroscopy (XPS), Field emission scanning electron microscopy (FESEM), micro Raman spectroscopy and UV–vis spectroscopy. The PEC study of the as-grown Al{sub x}In{sub 1−x}N thin films targeted for water splitting application were performed in the presence of simulated solar irradiation of AM 1.5G (100 mW/cm{sup 2}). The PEC results revealed that the photocurrent for the Al{sub x}In{sub 1−x}N thin film grown at nitrogen flow rate of 80 sccm is ∼10-fold higher than the dark current. From the Mott–Schottky (MS) plots it was deduced that by increasing N{sub 2} flow rate up to 80 sccm, the flat band potential shifts toward more negative values. The good photoelectrochemical behavior of Al{sub x}In{sub 1−x}N thin films showed that this material could be a potential candidate for PEC water splitting. - Highlights: • Al{sub x}In{sub 1−x}N films were grown by Plasma-aided dual source reactive evaporation. • Effect of nitrogen flow rate on the films properties was investigated. • The band gap of the films decreased from 2.33 to 1.92 eV. • A good photoelectrochemical behavior of the Al{sub x}In{sub 1−x}N thin films was shown. • The photocurrent for the Al{sub 0.55}In{sub 0.45}N films is ∼10-fold higher than dark current.

  13. Influence of pulse ratio on codeposition of copper species with calcium phosphate coatings on titanium by means of electrochemically assisted deposition.

    Science.gov (United States)

    Wolf-Brandstetter, Cornelia; Oswald, Steffen; Bierbaum, Susanne; Wiesmann, Hans-Peter; Scharnweber, Dieter

    2014-01-01

    Aim of this study was to combine the well-known biocompatibility and ostoeconductivity of thin calcium phosphate coatings on titanium with proangiogenic signals from codeposited copper species. Copper species could be integrated in mineral layers based on hydroxyapatite by means of electrochemically assisted deposition from electrolytes containing calcium, phosphate, and copper ions. Different combinations of duration and intensity of galvanostatic pulses result in different amounts of deposited calcium phosphate and of copper species even for the same applied total charge. Absolute amounts of copper varied between 2.1 and 6.9 μg/cm², and the copper was distributed homogeneously as shown by EDX mapping. The presence of copper did not change the crystalline phase of deposited calcium phosphate (hydroxyapatite) but provoked a significant decrease in deposited amounts by factor 3 to 4. The copper was deposited mainly as Cu(I) species with a minor fraction of basic copper phosphates. Reduction of copper occurred not only at the surface of titanium but also within the hydroxyapatite coating due to the reaction with hydrogen produced by the electrolysis of water during the cathodic polarization of the substrate. Copyright © 2013 Wiley Periodicals, Inc.

  14. Growth modes and epitaxy of FeAl thin films on a-cut sapphire prepared by pulsed laser and ion beam assisted deposition

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Xiang; Trautvetter, Moritz; Ziemann, Paul [Institut für Festkörperphysik, Universität Ulm, Albert-Einstein-Allee 11, 89069 Ulm (Germany); Wiedwald, Ulf [Institut für Festkörperphysik, Universität Ulm, Albert-Einstein-Allee 11, 89069 Ulm (Germany); Fakultät für Physik, Universität Duisburg-Essen, Lotharstraße 1, 47057 Duisburg (Germany)

    2014-01-14

    FeAl films around equiatomic composition are grown on a-cut (112{sup ¯}0) sapphire substrates by ion beam assisted deposition (IBAD) and pulsed laser deposition (PLD) at ambient temperature. Subsequent successive annealing is used to establish chemical order and crystallographic orientation of the films with respect to the substrate. We find a strongly [110]-textured growth for both deposition techniques. Pole figures prove the successful preparation of high quality epitaxial films by PLD with a single in-plane orientation. IBAD-grown films, however, exhibit three in-plane orientations, all of them with broad angular distributions. The difference of the two growth modes is attributed to the existence of a metastable intermediate crystalline orientation as concluded from nonassisted sputter depositions at different substrate temperatures. The formation of the chemically ordered crystalline B2 phase is accompanied by the expected transition from ferromagnetic to paramagnetic behavior of the films. In accordance with the different thermally induced structural recovery, we find a step-like magnetic transition to paramagnetic behavior after annealing for 1 h at T{sub A} = 300 °C for IBAD deposition, while PLD-grown films show a gradual decrease of ferromagnetic signals with rising annealing temperatures.

  15. New bio-active, antimicrobial and adherent coatings of nanostructured carbon double-reinforced with silver and silicon by Matrix-Assisted Pulsed Laser Evaporation for medical applications

    Science.gov (United States)

    Duta, L.; Ristoscu, C.; Stan, G. E.; Husanu, M. A.; Besleaga, C.; Chifiriuc, M. C.; Lazar, V.; Bleotu, C.; Miculescu, F.; Mihailescu, N.; Axente, E.; Badiceanu, M.; Bociaga, D.; Mihailescu, Ion N.

    2018-05-01

    We report on Matrix-Assisted Pulsed Laser Evaporation (MAPLE) deposition of Carbon thin films, simple or reinforced with intended concentrations of Ag and Si. A KrF∗ (λ = 248 nm, τFWHM ≤ 25 ns, ν = 10 Hz) excimer laser was used for irradiation. The effect of a post-deposition thermal treatment in vacuum was studied. Besides detailed morphological, compositional, structural and pull-out adherence characterizations, the potential of the carbonaceous films for medical applications was investigated in vitro by anti-biofilm and cytocompatibility assays. The microscopic images evidenced no delaminations. Micro-Raman spectroscopy revealed a graphitization tendency depending on preparation conditions, thermal treatment and reinforcing agents' presence. Adherence values improved considerably after thermal treatment. In vitro biological evaluation showed that the films containing ∼1.85 at.% Ag were non-cytotoxic for MG63 cells, while eliciting a limited antimicrobial activity. The increase of Ag content to 3.6 at.% results in a significant enhancement of antimicrobial activity, whilst maintaining the cytotoxic action and adherence characteristics at acceptable levels. We propose a new class of metamaterials based on C reinforced with Ag and Si obtained by MAPLE for medical applications, i.e. the prevention and treatment of various infections associated with biofilms developed on implants and other medical equipments.

  16. Numerical analysis and simulation of behavior of high burn-up PWR fuel pulse-irradiated in reactivity-initiated accident conditions

    International Nuclear Information System (INIS)

    Suzuki, M.; Sugiyama, T.; Udagawa, Y.; Nagase, F.; Fuketa, T.

    2010-01-01

    The four cases of the NSRR experiments, consisting of two room temperature tests and two high temperature tests, using high burn-up PWR fuel rods are analyzed by using the RANNS code to discuss the fuel behavior in hypothetical pulse-irradiation conditions, and the results are compared with metallography observations of ruptured claddings. The cladding rupture occurred by a shear sliding which starts from the tip of incipient crack generated in the hydride dense layer. The analyses reveal that the onset of shear sliding leading to cladding rupture can be closely associated with the stress intensity factor KI at the crack tip and local plastic strain evolution around the tip as well, and that these two factors depend also on the temperature of cladding. Simulation calculations on the basis of experimental conditions reveals that the cladding stress is dependent on the height and half-width of pulse power, and for the same integral enthalpy of pulse a larger half-width mitigates the severity of transient and decreases KI to allow plastic strain by temperature rise, thus failure possibility would be markedly decreased

  17. Morphology and structure evolution of Cu(In,Ga)S{sub 2} films deposited by reactive magnetron co-sputtering with electron cyclotron resonance plasma assistance

    Energy Technology Data Exchange (ETDEWEB)

    Nie, Man, E-mail: man.nie@helmholtz-berlin.de; Ellmer, Klaus [Department of Solar Fuels and Energy Storage Materials, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, D14109 Berlin (Germany)

    2014-02-28

    Cu(In,Ga)S{sub 2} (CIGS) films were deposited on Mo coated soda lime glass substrates using an electron cyclotron resonance plasma enhanced one-step reactive magnetron co-sputtering process (ECR-RMS). The crystalline quality and the morphology of the Cu(In,Ga)S{sub 2} films were investigated by X-ray diffraction, atomic force microscopy, scanning electron microscopy, and X-ray fluorescence. We also compared these CIGS films with films previously prepared without ECR assistance and find that the crystallinity of the CIGS films is correlated with the roughness evolution during deposition. Atomic force microscopy was used to measure the surface topography and to derive one-dimensional power spectral densities (1DPSD). All 1DPSD spectra of CIGS films exhibit no characteristic peak which is typical for the scaling of a self-affine surface. The growth exponent β, characterizing the roughness R{sub q} evolution during the film growth as R{sub q} ∼ d{sup β}, changes with film thickness. The root-mean-square roughness at low temperatures increases only slightly with a growth exponent β = 0.013 in the initial growth stage, while R{sub q} increases with a much higher exponent β = 0.584 when the film thickness is larger than about 270 nm. Additionally, we found that the H{sub 2}S content of the sputtering atmosphere and the Cu- to-(In + Ga) ratio has a strong influence of the morphology of the CIGS films in this one-step ECR-RMS process.

  18. Obtainment of the subcritical reactivity by mean of measurement of APSD and CPSD employing pulse mode detectors in the IPEN/MB-01 reactor

    International Nuclear Information System (INIS)

    Lee, Seung Min

    2014-01-01

    This work presents a new experimental approach to determine the reactivity levels of subcritical systems. The method employs the subcritical kinetic model developed by Gandini and Salvatores and it is based only on measured quantities such as counting rates of the detectors employed in the experiments and the parameters arising from the least squares fitting of the APSD (Auto Power Spectral Density) and CPSD (Cross Power Spectral Density). Detector efficiencies, quantity required in other procedures such as Neutron Source Multiplication (NSM) method, are not needed in the proposed method. The only hypothesis made in the method was the independence of the effective delayed neutron fraction and the prompt neutron generation time to the subcriticality level of the system. The proposed method was applied to measure the reactivity of several subcritical configurations of the IPEN/MB-01 reactor. Measurements of APSD and CPSD were performed in several degrees of subcriticality (up to around -7000 pcm). The spectral densities data were least squares fitted to get the prompt decay mode (α) and other quantities. Beside the startup source of the facility, an external neutron source of Am-Be was installed near the core in order to improve neutron counting statistics. The final experimental results are of good quality. The proposed experimental method shows clearly that the classical point kinetic theory cannot describe the measured reactivity. Instead, the reactivity inferred from this model follows closely the subcriticality index (ζ) for the source arrangements in the experiment. The agreement of the MCNP5 and GPT-TORT results, both with ENDF/B-VII.0 as the basic nuclear data library, when compared to the corresponding experimental ones was also good. (author)

  19. Effect of nitrogen doping on TiO.sub.x./sub.N.sub.y./sub. thin film formation at reactive high-power pulsed magnetron sputtering

    Czech Academy of Sciences Publication Activity Database

    Straňák, Vítězslav; Quaas, M.; Bogdanowicz, R.; Steffen, H.; Wulff, H.; Hubička, Zdeněk; Tichý, M.; Hippler, R.

    2010-01-01

    Roč. 43, č. 28 (2010), s. 1-7 ISSN 0022-3727 R&D Projects: GA AV ČR KAN301370701; GA MŠk(CZ) 1M06002 Grant - others:AVČR(CZ) M100100915 Institutional research plan: CEZ:AV0Z10100522 Keywords : magnetron sputtering * TiO 2 * pulse discharge * XRD * band gap Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.105, year: 2010 http://iopscience.iop.org/0022-3727/43/28/285203/

  20. Influence of the reactive atmosphere on the formation of nanoparticles in the plasma plume induced by nanosecond pulsed laser irradiation of metallic targets at atmospheric pressure and high repetition rate

    Energy Technology Data Exchange (ETDEWEB)

    Girault, M. [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS-Univ. Bourgogne Franche-Comté, 9 Av. A. Savary, BP 47 870, F-21078 Dijon Cedex (France); Le Garrec, J.-L.; Mitchell, J.B.A. [Institut de Physique de Rennes, UMR 6251 CNRS-Université de Rennes 1, 35042 Rennes Cedex (France); Jouvard, J.-M. [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS-Univ. Bourgogne Franche-Comté, 9 Av. A. Savary, BP 47 870, F-21078 Dijon Cedex (France); Carvou, E. [Institut de Physique de Rennes, UMR 6251 CNRS-Université de Rennes 1, 35042 Rennes Cedex (France); Menneveux, J.; Yu, J. [Institut Lumière Matière, UMR5306 Université Lyon 1-CNRS, Université de Lyon, 69622 Villeurbanne Cedex (France); Ouf, F.-X. [Institut de Radioprotection et de Sureté Nucléaire IRSN/PSN-RES/SCA/LPMA BP 68, 91192 Gif-Sur-Yvette (France); Carles, S. [Institut de Physique de Rennes, UMR 6251 CNRS-Université de Rennes 1, 35042 Rennes Cedex (France); Potin, V.; Pillon, G.; Bourgeois, S. [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS-Univ. Bourgogne Franche-Comté, 9 Av. A. Savary, BP 47 870, F-21078 Dijon Cedex (France); Perez, J. [Synchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin, F-91192 Gif-sur-Yvette Cedex (France); Marco de Lucas, M.C., E-mail: delucas@u-bourgogne.fr [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS-Univ. Bourgogne Franche-Comté, 9 Av. A. Savary, BP 47 870, F-21078 Dijon Cedex (France); and others

    2016-06-30

    Highlights: • NPs formed in a plasma-plume during laser irradiation of metals (Al, Ti, Ag) were studied. • In situ SAXS and ex situ TEM, XRD and Raman spectra were measured. • NPs size decreased when increasing the O{sub 2} fraction in a controlled O{sub 2}+N{sub 2} atmosphere. • The oxidation of metal NPs in the plasma restricts the increase of the size of the NPs. - Abstract: The influence of a reactive atmosphere on the formation of nanoparticles (NPs) in the plasma plume generated by nanosecond pulsed laser irradiation of metal targets (Ti, Al, Ag) was probed in situ using Small Angle X-ray Scattering (SAXS). Air and different O{sub 2}–N{sub 2} gas mixtures were used as reactive gas within atmospheric pressure. SAXS results showed the formation of NPs in the plasma-plume with a mean radius varying in the 2–5 nm range. A decrease of the NPs size with increasing the O{sub 2} percentage in the O{sub 2}–N{sub 2} gas mixture was also showed. Ex situ observations by transmission electron microscopy and structural characterizations by X-ray diffraction and Raman spectroscopy were also performed for powders collected in experiments done using air as ambient gas. The stability of the different metal oxides is discussed as being a key parameter influencing the formation of NPs in the plasma-plume.

  1. SPF-RR sequential photothermal fractional resurfacing and remodeling with the variable pulse Er:YAG laser and scanner-assisted Nd:YAG laser.

    Science.gov (United States)

    Marini, Leonardo

    2009-12-01

    Many different lasers, polychromatic high-intensity light sources (PCLs), and RF devices have claimed clinical efficacy in rejuvenating the skin. In this study, the sequential combination of two different laser wavelengths was evaluated to produce reliably significant clinical improvements optimizing treatment parameters. The left volar aspects of the forearms of four volunteers were treated with nine different parameter settings using a variable pulsewidth fractional Er:YAG 2940-nm laser with and without air cooling. The pain perception level was recorded on a 0-10 point scale (0=No pain; 10=Most severe pain). Three evaluations were made: during treatment, immediately after treatment, and 5 minutes after treatment. The same investigation was made on the right volar aspects of the same four volunteers using a short-pulse, random pattern, 3-mm spot, scanner-assisted Nd-YAG 1064-nm laser at 0.3 ms pulsewidth at seven different parameter settings. Clinical evaluations were made concerning erythema and edema 3 days after treatment, as well as pre-operative and 60 days postoperative skin texture plus color uniformity. Considering that the majority of cosmetic patients are willing to accept a relatively short and uneventful downtime (2-4 days according to a study we are presently conducting) and do prefer to limit their intra- and postoperative pain to a minimum, the best combination of clinical improvement matching these two important parameters were selected for our study. A treatment strategy combining two sequential passes of long-pulse Nd:YAG laser (Nd:YAG-LP) at 0.3 and 35 ms followed by two passes of long-pulse fractional Er:YAG laser (Er:YAG-FT) at 600 micros was designed to treat the facial regions of 10 volunteers affected by a combination of intrinsic (chrono-) and extrinsic (mostly photo-) aging. The pain perception level was recorded on a 0-10 scale (0=No pain; 10=Most severe pain). Three evaluations were made: during, immediately after, and 5 minutes after

  2. In vitro behavior of human mesenchymal stem cells on poly(N-isopropylacrylamide) based biointerfaces obtained by matrix assisted pulsed laser evaporation

    Science.gov (United States)

    Icriverzi, Madalina; Rusen, Laurentiu; Sima, Livia Elena; Moldovan, Antoniu; Brajnicov, Simona; Bonciu, Anca; Mihailescu, Natalia; Dinescu, Maria; Cimpean, Anisoara; Roseanu, Anca; Dinca, Valentina

    2018-05-01

    The use of smart coatings with tunable characteristics in bioengineering fields is directly correlated with the surface chemical and topographical properties, the method of preparation, and also with the type of cells implied for the specific application. In this work, a versatile surface modification technique based on the use of lasers (Matrix-Assisted Pulsed Laser Evaporation (MAPLE)) was used to yield poly(N-isopropylacrylamide) (pNIPAM) and its derivatives (amine, azide and amide terminated pNIPAM) functional and termoresponsive thin films. Surface properties of pNIPAM and its derivative films such as morphology, roughness and hydrophobic/hydrophilic character, as well as the thermoresponsive capacity were investigated by atomic force microscopy and contact angle measurements. The chemical characteristics of the pNIPAM based thin films were analysed by Fourier Transform Infrared Spectroscopy (FTIR). The chemical functionality was kept for all the samples obtained by MAPLE and the thermoresponse was demonstrated by the change in the contact angle and thickness values when the temperature was shifted from 37 °C to 24 °C for all the materials tested, with a smaller change for maleimide terminated pNIPAM. Biological assays performed in vitro (fluorescence microscopy and Scanning Electron Microscopy (SEM)) confirmed the conditioning of the early mesenchymal stem cell (MSC) growth by specific chemistry of the coatings. The cell imaging analysis revealed no cytotoxic effect of pNIPAM surfaces irrespective of type of functionalization. An increased proliferation rate of the cells grown on pNIPAM-azide surfaces and a lower cell density on pNIPAM-maleimide surfaces compared to the pNIPAM surfaces was observed, which can direct their use to potential surfaces in regenerative medicine approaches.

  3. A comparison of reactive plasma pre-treatments on PET substrates by Cu and Ti pulsed-DC and HIPIMS discharges

    Energy Technology Data Exchange (ETDEWEB)

    Audronis, M., E-mail: m.audronis@yahoo.co.uk [Gencoa Ltd, Physics Road, Speke, Liverpool, L24 9HP (United Kingdom); Hinder, S.J. [The Surface Analysis Laboratory, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, GU2 7XH (United Kingdom); Mack, P. [ThermoFisher Scientific Ltd, Imberhorne Lane, East Grinstead, Sussex, RH19 1UB (United Kingdom); Bellido-Gonzalez, V. [Gencoa Ltd, Physics Road, Speke, Liverpool, L24 9HP (United Kingdom); Bussey, D.; Matthews, A. [Department of Engineering Materials, University of Sheffield, Sheffield S1 3JD (United Kingdom); Baker, M.A. [The Surface Analysis Laboratory, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, GU2 7XH (United Kingdom)

    2011-12-30

    PET web samples have been treated by magnetically enhanced glow discharges powered using either medium frequency pulse direct current (p-DC) or low frequency high power pulse (HIPIMS) sources. The plasma pre-treatment processes were carried out in an Ar-O{sub 2} atmosphere using either Cu or Ti sputter targets. XPS, AFM and sessile drop water contact angle measurements have been employed to examine changes in surface chemistry and morphology for different pre-treatment process parameters. Deposition of metal oxide onto the PET surface is observed as a result of the sputter magnetron-based glow discharge web treatment. Using the Cu target, both the p-DC and HIPIMS processes result in the formation of a thin CuO layer (with a thickness between 1 and 11 nm) being deposited onto the PET surface. Employing the Ti target, both p-DC and HIPIMS processes give rise to a much lower concentration of Ti (< 5 at.%), in the form of TiO{sub 2} on the PET treated surface. The TiO{sub 2} is probably distributed as an island-like distribution covering the PET surface. Presence of Cu and Ti oxide constituents on the treated PET is beneficial in aiding the adhesion but alone (i.e. without oxygen plasma activation) is not enough to provide very high levels of hydrophilicity as is clear from sessile drop water contact angle measurements on aged samples. Exposure to the plasma treatments leads to a small amount of roughening of the substrate surface, but the average surface roughness in all cases is below 2.5 nm. The PET structure at the interface with a coating is mostly or wholly preserved. The oxygen plasma treatment, metal oxide deposition and surface roughening resulting from the HIPIMS and p-DC treatments will promote adhesion to any subsequent thin film that is deposited immediately following the plasma treatment.

  4. Surface treatment of diamond-like carbon films by reactive Ar/CF{sub 4} high-power pulsed magnetron sputtering plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, Takashi, E-mail: t-kimura@nitech.ac.jp [Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan); Nishimura, Ryotaro [Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan); Azuma, Kingo [Department of Electrical Engineering and Computer Sciences, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280 (Japan); Nakao, Setsuo; Sonoda, Tsutomu; Kusumori, Takeshi; Ozaki, Kimihiro [National Institute of Advanced Industrial Science and Technology (AIST) - Chubu, 2266-98 Anagahora, Moriyama, Nagoya 463-8560 (Japan)

    2015-12-15

    Surface modification of diamond-like carbon films deposited by a high-power pulsed magnetron sputtering (HPPMS) of Ar was carried out by a HPPMS of Ar/CF{sub 4} mixture, changing a CF{sub 4} fraction from 2.5% to 20%. The hardness of the modified films markedly decreased from about 13 to about 3.5 GPa with increasing CF{sub 4} fraction, whereas the water contact angle of the modified films increased from 68° to 109° owing to the increase in the CF{sub x} content on the film surface. C 1s spectra in X-ray photoelectron spectroscopy indicated that a graphitic structure of modified films was formed at CF{sub 4} fractions less than 5%, above which the modified films possessed a polymer-like structure. Influence of treatment time on the properties of the modified films was also investigated in the range of treatment time from 5 to 30 min. The properties of the modified films did not depend on the treatment time in the range of treatment time longer than 10 min, whereas the water contact angle was not sensitive to the treatment time at any treatment time.

  5. Effects of Temperature on the Microstructure and Magnetic Property of Cr-Doped ZnO DMS Prepared by Hydrothermal Route Assisted by Pulsed Magnetic Fields

    Directory of Open Access Journals (Sweden)

    Shiwei Wang

    2013-01-01

    Full Text Available In the present work, Cr-doped ZnO diluted magnetic semiconductor was synthesized by hydrothermal method under pulsed magnetic fields. The samples were characterized by XRD, SEM, VSM, Raman, and XPS techniques. Results demonstrated that Zn ions in the ZnO crystal lattice were partially displaced by Chromium (III ions. All samples show room temperature ferromagnetism which was enhanced by pulsed magnetic fields. The mechanism of ferromagnetism of Cr-doped ZnO particles was discussed.

  6. Deposition of single-layer and graded aluminum nitride coatings on vanadium substrates using ion-beam assisted reactive evaporation (ITER task no. ETA-EC-BLR26)

    International Nuclear Information System (INIS)

    Jamarani, F.; Lang, R.; Owles, R.

    1994-06-01

    The objective of the project has been to develop a reactive evaporation process for the fabrication of aluminum nitride coatings on pure vanadium substrates. The aluminum nitride coatings are to be used as electrical insulators on the surfaces of structural materials in contact with liquid metal coolants. (author). 9 refs., 2 tabs., 5 figs

  7. Pulse Generator

    Science.gov (United States)

    Greer, Lawrence (Inventor)

    2017-01-01

    An apparatus and a computer-implemented method for generating pulses synchronized to a rising edge of a tachometer signal from rotating machinery are disclosed. For example, in one embodiment, a pulse state machine may be configured to generate a plurality of pulses, and a period state machine may be configured to determine a period for each of the plurality of pulses.

  8. Pulsed electric fields

    Science.gov (United States)

    The concept of pulsed electric fields (PEF) was first proposed in 1967 to change the behavior or microorganisms. The electric field phenomenon was identified as membrane rupture theory in the 1980s. Increasing the membrane permeability led to the application of PEF assisted extraction of cellular co...

  9. Improving tribological properties of (Zn–Ni)/nano Al{sub 2}O{sub 3} composite coatings produced by ultrasonic assisted pulse plating

    Energy Technology Data Exchange (ETDEWEB)

    Ataie, Sayed Alireza, E-mail: ataie_s_alireza@metaleng.iust.ac.ir; Zakeri, Alireza

    2016-07-25

    In this study pulse electroplating was used to deposit the composite coating of (Zn–Ni) strengthened by Al{sub 2}O{sub 3} nanoparticles on mild steel plate. The effect of Al{sub 2}O{sub 3} fraction and ultrasonic irradiation on the properties of the composite coating was also investigated. Scanning electron microscopy and energy dispersive spectroscopy techniques were employed to characterize the morphology and composition of the coating. Topography and surface roughness were investigated by atomic force microscopy. Also in order to evaluate the mechanical properties of the coating micro hardness and wear tests were conducted. It was found that coating hardness was increased from 538 HV to 750 HV and friction coefficient was decreased from 0.588 to 0.392. Results revealed that tribological properties of coating could be improved significantly by using suitable ultrasonic intensity simultaneously with pulse plating. - Highlights: • SEM indicated on the elimination of cracks and pores when ultrasounds were used. • XRD result showed nano sized grains of Zn–Ni matrix was developed in this research. • Simultaneous pulse plating and ultrasonic conditions improved the properties of the coating. • A (Zn–Ni)/nano alumina uniform composite coating for especial applications was developed. • Micro hardness and wear behavior of the coating was modified by intensifying the ultrasound.

  10. Laser assisted removal of synthetic painting-conservation materials using UV radiation of ns and fs pulse duration: Morphological studies on model samples

    International Nuclear Information System (INIS)

    Pouli, P.; Nevin, A.; Andreotti, A.; Colombini, P.; Georgiou, S.; Fotakis, C.

    2009-01-01

    In an effort to establish the optimal parameters for the cleaning of complex layers of polymers (mainly based on acrylics, vinyls, epoxys known as Elvacite, Laropal, Paraloid B72, among others) applied during past conservation treatments on the surface of wall paintings, laser cleaning tests were performed with particular emphasis on the plausible morphological modifications induced in the remaining polymeric material. Pulse duration effects were studied using laser systems of different pulse durations (ns and fs) at 248 nm. Prior to tests on real fragments from the Monumental Cemetery in Pisa (Italy) which were coated with different polymers, attention was focused on the study of model samples consisting of analogous polymer films cast on quartz disks. Ultraviolet irradiation is strongly absorbed by the studied materials both in ns and fs irradiation regimes. However, it is demonstrated that ultrashort laser pulses result in reduced morphological alterations in comparison to ns irradiation. In addition, the dependence of the observed alterations on the chemical composition of the consolidation materials in both regimes was examined. Most importantly, it was shown that in this specific conservation problem, an optimum cleaning process may rely not only on the minimization of laser-induced morphological changes but also on the exploitation of the conditions that favour the disruption of the adhesion between the synthetic material and the painting.

  11. Amino-terminal pro-B-type natriuretic peptide and high-sensitivity C-reactive protein but not cystatin C predict cardiovascular events in male patients with peripheral artery disease independently of ambulatory pulse pressure.

    Science.gov (United States)

    Skoglund, Per H; Arpegård, Johannes; Ostergren, Jan; Svensson, Per

    2014-03-01

    Patients with peripheral arterial disease (PAD) are at high risk for cardiovascular (CV) events. We have previously shown that ambulatory pulse pressure (APP) predicts CV events in PAD patients. The biomarkers amino-terminal pro-B-type natriuretic peptide (NT-proBNP), high-sensitivity C-reactive protein (hs-CRP), and cystatin C are related to a worse outcome in patients with CV disease, but their predictive values have not been studied in relation to APP. Blood samples and 24-hour measurements of ambulatory blood pressure were examined in 98 men referred for PAD evaluation during 1998-2001. Patients were followed for a median of 71 months. The outcome variable was CV events defined as either CV mortality or any hospitalization for myocardial infarction, stroke, or coronary revascularization. The predictive values of log(NT-proBNP), log(hs-CRP), and log(cystatin C) alone and together with APP were assessed by multivariable Cox regression. Area under the curve (AUC) and net reclassification improvement (NRI) were calculated compared with a model containing other significant risk factors. During follow-up, 36 patients had at least 1 CV event. APP, log(NT-proBNP), and log(hs-CRP) all predicted CV events in univariable analysis, whereas log(cystatin C) did not. In multivariable analysis log(NT-proBNP) (hazard ratio (HR) = 1.62; 95% confidence interval (CI) = 1.05-2.51) and log(hs-CRP) (HR = 1.63; 95% CI = 1.19-2.24) predicted events independently of 24-hour PP. The combination of log(NT-proBNP), log(hs-CRP), and average day PP improved risk discrimination (AUC = 0.833 vs. 0.736; P < 0.05) and NRI (37%; P < 0.01) when added to other significant risk factors. NT-proBNP and hs-CRP predict CV events independently of APP and the combination of hs-CRP, NT-proBNP, and day PP improves risk discrimination in PAD patients.

  12. Effect of nitrogen environment on NdFeB thin films grown by radio frequency plasma beam assisted pulsed laser deposition

    International Nuclear Information System (INIS)

    Constantinescu, C.; Patroi, E.; Codescu, M.; Dinescu, M.

    2013-01-01

    Highlights: ► NdFeB thin films grown by PLD, in vacuum and in nitrogen, are presented. ► Nitrogen inclusion in thin film structures is related to improved coercitivity. ► Magnetical, optical and morphological properties of the thin films are discussed. - Abstract: NdFeB is a very attractive material for applications in electrical engineering and in electronics, for high-tech devices where high coercive field and high remanence are needed. In this paper we demonstrate that the deposition of nitrogen doped NdFeB thin films by pulsed laser deposition, in the presence of a nitrogen radiofrequency plasma beam, exhibit improved magnetic properties and surface morphology, when compared to vacuum deposited NdFeB layers. A Nd:YAG pulsed laser (3ω and 4ω) was focused on a NdFeB target, in vacuum, or in the presence of a nitrogen plasma beam. Substrate temperature (RT-850 °C), nitrogen gas pressure, and radiofrequency power (75–150 W), were particularly varied. The thin films were investigated by means of X-ray diffraction, atomic force microscopy, scanning electron microscopy, spectroscopic-ellipsometry, and vibrating sample magnetometry.

  13. Effect of nitrogen environment on NdFeB thin films grown by radio frequency plasma beam assisted pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Constantinescu, C., E-mail: catalin.constantinescu@inflpr.ro [National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor bd., Magurele, RO-077125, Bucharest (Romania); Patroi, E.; Codescu, M. [National Institute for Research and Development in Electrical Engineering - Advanced Research, 313 Spl. Unirii, Sector 3, RO-030138, Bucharest (Romania); Dinescu, M. [National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor bd., Magurele, RO-077125, Bucharest (Romania)

    2013-03-01

    Highlights: Black-Right-Pointing-Pointer NdFeB thin films grown by PLD, in vacuum and in nitrogen, are presented. Black-Right-Pointing-Pointer Nitrogen inclusion in thin film structures is related to improved coercitivity. Black-Right-Pointing-Pointer Magnetical, optical and morphological properties of the thin films are discussed. - Abstract: NdFeB is a very attractive material for applications in electrical engineering and in electronics, for high-tech devices where high coercive field and high remanence are needed. In this paper we demonstrate that the deposition of nitrogen doped NdFeB thin films by pulsed laser deposition, in the presence of a nitrogen radiofrequency plasma beam, exhibit improved magnetic properties and surface morphology, when compared to vacuum deposited NdFeB layers. A Nd:YAG pulsed laser (3{omega} and 4{omega}) was focused on a NdFeB target, in vacuum, or in the presence of a nitrogen plasma beam. Substrate temperature (RT-850 Degree-Sign C), nitrogen gas pressure, and radiofrequency power (75-150 W), were particularly varied. The thin films were investigated by means of X-ray diffraction, atomic force microscopy, scanning electron microscopy, spectroscopic-ellipsometry, and vibrating sample magnetometry.

  14. Reactive Arthritis

    Directory of Open Access Journals (Sweden)

    Eren Erken

    2013-06-01

    Full Text Available Reactive arthritis is an acute, sterile, non-suppurative and inflammatory arthropaty which has occured as a result of an infectious processes, mostly after gastrointestinal and genitourinary tract infections. Reiter syndrome is a frequent type of reactive arthritis. Both reactive arthritis and Reiter syndrome belong to the group of seronegative spondyloarthropathies, associated with HLA-B27 positivity and characterized by ongoing inflammation after an infectious episode. The classical triad of Reiter syndrome is defined as arthritis, conjuctivitis and urethritis and is seen only in one third of patients with Reiter syndrome. Recently, seronegative asymmetric arthritis and typical extraarticular involvement are thought to be adequate for the diagnosis. However, there is no established criteria for the diagnosis of reactive arthritis and the number of randomized and controlled studies about the therapy is not enough. [Archives Medical Review Journal 2013; 22(3.000: 283-299

  15. Identification and Removal of High Frequency Temporal Noise in a Nd:YAG Macro-Pulse Laser Assisted with a Diagnostic Streak Camera

    International Nuclear Information System (INIS)

    Kent Marlett; Ke-Xun Sun

    2004-01-01

    This paper discusses the use of a reference streak camera (SC) to diagnose laser performance and guide modifications to remove high frequency noise from Bechtel Nevada's long-pulse laser. The upgraded laser exhibits less than 0.1% high frequency noise in cumulative spectra, exceeding National Ignition Facility (NIF) calibration specifications. Inertial Confinement Fusion (ICF) experiments require full characterization of streak cameras over a wide range of sweep speeds (10 ns to 480 ns). This paradigm of metrology poses stringent spectral requirements on the laser source for streak camera calibration. Recently, Bechtel Nevada worked with a laser vendor to develop a high performance, multi-wavelength Nd:YAG laser to meet NIF calibration requirements. For a typical NIF streak camera with a 4096 x 4096 pixel CCD, the flat field calibration at 30 ns requires a smooth laser spectrum over 33 MHz to 68 GHz. Streak cameras are the appropriate instrumentation for measuring laser amplitude noise at these very high frequencies since the upper end spectral content is beyond the frequency response of typical optoelectronic detectors for a single shot pulse. The SC was used to measure a similar laser at its second harmonic wavelength (532 nm), to establish baseline spectra for testing signal analysis algorithms. The SC was then used to measure the new custom calibration laser. In both spatial-temporal measurements and cumulative spectra, 6-8 GHz oscillations were identified. The oscillations were found to be caused by inter-surface reflections between amplifiers. Additional variations in the SC spectral data were found to result from temperature instabilities in the seeding laser. Based on these findings, laser upgrades were made to remove the high frequency noise from the laser output

  16. Synthesis of high Al content AlxGa1−xN ternary films by pulsed laser co-ablation of GaAs and Al targets assisted by nitrogen plasma

    International Nuclear Information System (INIS)

    Cai, Hua; You, Qinghu; Hu, Zhigao; Guo, Shuang; Yang, Xu; Sun, Jian; Xu, Ning; Wu, Jiada

    2014-01-01

    Highlights: • Al x Ga 1−x N films were synthesized by co-ablation of an Al target and a GaAs target. • Nitrogen plasma was used to assist the synthesis of Al x Ga 1−x N ternary films. • The Al x Ga 1−x N films are slightly rich in N with an Al content above 0.6. • The Al x Ga 1−x N films are hexagonal wurtzite in crystal structure. • The Al x Ga 1−x N films have an absorption edge of 260 nm and a band gap of 4.7 eV. - Abstract: We present the synthesis of Al x Ga 1−x N ternary films by pulsed laser co-ablation of a polycrystalline GaAs target and a metallic Al target in the environment of nitrogen plasma which provides nitrogen for the films and assists the formation of nitride films. Field emission scanning electron microscopy exposes the smooth surface appearance and dense film structure. X-ray diffraction, Fourier-transform infrared spectroscopy and Raman scattering spectroscopy reveal the hexagonal wurtzite structure. Optical characterization shows high optical transmittance with an absorption edge of about 260 nm and a band gap of 4.7 eV. Compositional analysis gives the Al content of about 0.6. The structure and optical properties of the Al x Ga 1−x N films are compared with those of binary GaN and AlN films synthesized by ablating GaAs or Al target with the same nitrogen plasma assistance

  17. PUSPATI Triga Reactor pulsing parameters

    Energy Technology Data Exchange (ETDEWEB)

    Auu, Gui Ah; Abu, Puad Haji; Yunus, Yaziz [PUSPATI, Selangor (Malaysia)

    1984-06-01

    The pulsing experiment was carried out as part of the commissioning activites of PUSPATI TRIGA Reactor (PTR). Several parameters of PTR were deduced from the experiment. It was found that the maximum temperature of the fuel was far below the safety limit when the maximum allowable positive reactivity of $3.00 was inserted into the core. The peak power achieved was 1354 Mw.

  18. Pulsed ion-beam assisted deposition of Ge nanocrystals on SiO{sub 2} for non-volatile memory device

    Energy Technology Data Exchange (ETDEWEB)

    Stepina, N.P. [Institute of Semiconductor Physics, Lavrenteva 13, 630090 Novosibirsk (Russian Federation)], E-mail: nstepina@mail.ru; Dvurechenskii, A.V.; Armbrister, V.A.; Kirienko, V.V.; Novikov, P.L.; Kesler, V.G.; Gutakovskii, A.K.; Smagina, Z.V.; Spesivtzev, E.V. [Institute of Semiconductor Physics, Lavrenteva 13, 630090 Novosibirsk (Russian Federation)

    2008-11-03

    A floating gate memory structure, utilizing Ge nanocrystals (NCs) deposited on tunnel SiO{sub 2}, have been fabricated using pulsed low energy ion-beam induced molecular-beam deposition (MBD) in ultra-high vacuum. The ion-beam action is shown to stimulate the nucleation of Ge NCs when being applied after thin Ge layer deposition. Growth conditions for independent change of NCs size and array density were established allowing to optimize the structure parameters required for memory device. Activation energy E = 0.25 eV was determined from the temperature dependence of NCs array density. Monte Carlo simulation has shown that the process, determining NCs array density, is the surface diffusion. Embedding of the crystalline Ge dots into silicon oxide was carried out by selective oxidation of Si(100)/SiO{sub 2} /Ge(NCs)/poly-Si structure. MOS-capacitor obtained after oxidation showed a hysteresis in its C-V curves attributed to charge retention in the Ge dots.

  19. Effect of nitrogen flow rate on structural, morphological and optical properties of In-rich In{sub x}Al{sub 1−x}N thin films grown by plasma-assisted dual source reactive evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Alizadeh, M., E-mail: alizadeh_kozerash@yahoo.com [Low Dimensional Materials Research Centre (LDMRC), Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Ganesh, V.; Goh, B.T. [Low Dimensional Materials Research Centre (LDMRC), Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Dee, C.F.; Mohmad, A.R. [Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, Bangi, Selangor (Malaysia); Rahman, S.A., E-mail: saadah@um.edu.my [Low Dimensional Materials Research Centre (LDMRC), Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2016-08-15

    Highlights: • In-rich In{sub x}Al{sub 1−x}N films were grown by Plasma-aided reactive evaporation. • Effect of nitrogen flow rate on the films properties was investigated. • The band gap of the films was varied from 1.17 to 0.90 eV. • By increasing N{sub 2} flow rate the In{sub x}Al{sub 1−x}N films tend to turn into amorphous state. • At higher N{sub 2} flow rate agglomeration of the particles is highly enhanced. - Abstract: In-rich In{sub x}Al{sub 1−x}N thin films were deposited on quartz substrate at various nitrogen flow rates by plasma-assisted dual source reactive evaporation technique. The elemental composition, surface morphology, structural and optical properties of the films were investigated by X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), Raman spectroscopy, X-ray diffraction (XRD), UV–vis spectrophotometer and photoluminescence (PL) measurements. XPS results revealed that the indium composition (x) of the In{sub x}Al{sub 1−x}N films increases from 0.90 to 0.97 as the nitrogen flow rate is increased from 40 to 100 sccm, respectively. FESEM images of the surface and cross-sectional microstructure of the In{sub x}Al{sub 1−x}N films showed that by increasing the N{sub 2} flow rate, the grown particles are highly agglomerated. Raman and XRD results indicated that by increasing nitrogen flow rate the In-rich In{sub x}Al{sub 1−x}N films tend to turn into amorphous state. It was found that band gap energy of the films are in the range of 0.90–1.17 eV which is desirable for the application of full spectra solar cells.

  20. Reactive Systems

    DEFF Research Database (Denmark)

    Aceto, Luca; Ingolfsdottir, Anna; Larsen, Kim Guldstrand

    A reactive system comprises networks of computing components, achieving their goals through interaction among themselves and their environment. Thus even relatively small systems may exhibit unexpectedly complex behaviours. As moreover reactive systems are often used in safety critical systems......, the need for mathematically based formal methodology is increasingly important. There are many books that look at particular methodologies for such systems. This book offers a more balanced introduction for graduate students and describes the various approaches, their strengths and weaknesses, and when...... they are best used. Milner's CCS and its operational semantics are introduced, together with the notions of behavioural equivalences based on bisimulation techniques and with recursive extensions of Hennessy-Milner logic. In the second part of the book, the presented theories are extended to take timing issues...

  1. Kinetic studies on a repetitively pulsed fast reactor

    International Nuclear Information System (INIS)

    Das, S.

    1982-01-01

    Neutronic analysis of an earlier proposed periodically pulsed fast reactor at Kalpakkam (KPFR) has been carried out numerically under equilibrium and transient conditions using the one-point model of reactor kinetics and the experimentally measured total worth of reactivity modulator, the parabolic coefficient of reactivity of the movable reflector and the mean prompt neutron lifetime. Results of steady-state calculations - treated on the basis of delayed neutron precursor and energy balances during a period of operation - have been compared with the analytical formulae of Larrimore for a parabolic reactivity input. Empirical relations for half-width of the fast neutron pulse, the peak pulse power and the power at first crossing of prompt criticality have been obtained and shown to be accurate enough for predicting steady-state power pulse characteristics of a periodically pulsed fast reactor. The concept of a subprompt-critical reactor has been used to calculate the fictitious delayed neutron fraction, β of the KPFR through a numerical experiment. Relative pulse height stability and pulse shape sensitivity to changes of maximum reactivity is discussed. With the aid of new safety concepts, the Power Amplification Factor (PAF) and the Pulse Growth Factor (Rsub(p)), the dynamics KPFR under accidental conditions has been studied for step and ramp reactivity perturbations. All the analysis has been done without taking account of reactivity feedback. (orig.)

  2. Additional ion bombardment in PVD processes generated by a superimposed pulse bias voltage

    International Nuclear Information System (INIS)

    Olbrich, W.; Kampschulte, G.

    1993-01-01

    The superimposed pulse bias voltage is a tool to apply an additional ion bombardment during deposition in physical vapour deposition (PVD) processes. It is generated by the combination of a d.c. ground voltage and a higher d.c. pulse voltage. Using a superimposed pulse bias voltage in ion-assisted PVD processes effects an additional all-around ion bombardment on the surface with ions of higher energy. Both metal and reactive or inert-gas ions are accelerated to the surface. The basic principles and important characteristics of this newly developed process such as ion fluxes or deposition rates are shown. Because of pulsing the high voltage, the deposition temperature does not increase much. The adhesion, structure, morphology and internal stresses are influenced by these additional ion impacts. The columnar growth of the deposited films could be suppressed by using the superimposed pulse bias voltage without increasing the deposition temperature. Different metallizations (Cr and Cu) produced by arc and sputter ion plating are investigated. Carbon-fibre-reinforced epoxy are coated with PVD copper films for further treatment in electrochemical processes. (orig.)

  3. Pulse plating

    CERN Document Server

    Hansal, Wolfgang E G; Green, Todd; Leisner, Peter; Reichenbach, Andreas

    2012-01-01

    The electrodeposition of metals using pulsed current has achieved practical importance in recent years. Although it has long been known that changes in potential, with or without polarity reversal, can significantly affect the deposition process, the practical application of this has been slow to be adopted. This can largely be explained in terms of the complex relationship between the current regime and its effect on the electrodeposition process. In order to harness these effects, an understanding of the anodic and cathodic electrochemical processes is necessary, together with the effects of polarity reversal and the rate of such reversals. In this new monograph, the basics of metal electrodeposition from solution are laid out in great detail in seven distinct chapters. With this knowledge, the reader is able to predict how a given pulse train profile can be adopted to achieve a desired outcome. Equally important is the choice of a suitable rectifier and the ancillary control circuits to enable pulse platin...

  4. Orifice microreactor for the production of an organic peroxide – non-reactive and reactive characterization

    NARCIS (Netherlands)

    Illg, T.; Hessel, V.; Löb, P.; Schouten, J.C.

    2012-01-01

    In this article, the transfer of a two-step, biphasic, and exothermic peroxide synthesis into a microreactor assisted process is discussed as well as the non-reactive and reactive characterization of the developed orifice microreactor. Residence time distribution measurements showed nearly ideal

  5. PUSPATI Triga Reactor pulsing parameters

    International Nuclear Information System (INIS)

    Gui Ah Auu; Puad Haji Abu; Yaziz Yunus

    1984-01-01

    The pulsing experiment was carried out as part of the commissioning activites of PUSPATI TRIGA Reactor (PTR). Several parameters of PTR were deduced from the experiment. It was found that the maximum temperature of the fuel was far below the safety limit when the maximum allowable positive reactivity of $3.00 was inserted into the core. The peak power achieved was 1354 Mw. (author)

  6. The Measurement of Reactivity In Multiregion Subcritical Systems by the Pulsed Neutron Technique; Mesure de la Reactivite dans les Systemes Sous-Critiques a Plusieurs Regions par la Methode des Neutrons Pulses; Izmerenie reaktivnosti v mnogozonnykh podkriticheskikh sistemakh metodom impul'snykh nejtronov; Mediciones de la Reactividad en Sistemas Subcriticos de Varias Regiones Mediante la Tecnica de los Neutrones Pulsados

    Energy Technology Data Exchange (ETDEWEB)

    Sherwin, J.; Leng, J. H. [United Kingdom Atomic Energy Authority, Windscale Works, Cumberland (United Kingdom)

    1965-10-15

    The prompt decay of a thermalized burst of neutrons in a multiregion subcritical system is examined using a two-group diffusion theory. It is shown that a relationship can be established between the prompt decay constant of the fundamental mode and the effective multiplication factor of the system in terms of two parameters, defined, for the purposes of this paper, as the reactor response coefficient and the prompt decay correction and which depend to a large extent on the spatial flux patterns within the system. For the uniform bare system, the response coefficient can be identified with the mean neutron lifetime in the system; for a multiregion system it represents a compound of the lifetimes in each region weighted by perturbation type integrals. The second parameter, the decay correction, can have no physical meaning in that it arises from an attempt to relate the two scales of reactivity involved; that is the scale using the prompt decay constant and the scale derived using the effective multiplication factor. The properties of these parameters are examined here with reference to an enriched uranium graphitemoderated reactor consisting of uniform core and reflector and it is shown that the two parameters are not uniquely defined by the reactivity of the system but depend on the method chosen to make the system subcritical. Two sets of measurements are treated by the theory. In one, the Windscale Advanced Gas-Cooled Reactor was shut down by a uniform poison. In the other the reactivity of a core in the zero-energy reactor HERO was varied by altering the loaded radius. The neutron pulse measurements are all shown to be in good agreement with more conventional methods of reactivity determination. Some discussion of the experimental techniques and the difficulties encountered in the graphite-moderated systems is presented. (author) [French] Les auteurs etudient la decroissance des neutrons instantanes d'une bouffee thermalisee de neutrons dans un systeme sous

  7. Pulsed power

    International Nuclear Information System (INIS)

    Anon.

    1977-01-01

    The key element of our pulsed power program is concentration of power in time and space by suppression of breakdown in dielectrics and in vacuum. Magnetically insulated vacuum transmission lines and magnetic suppression of insulator flashover have continued as the main reserch directions. Vacuum insulated line studies at Physics International have been expanded and a test bed at Sandia, called MITE (Magnetically Insulated Transmission Experiment), is under development. The choice for the baseline EBFA design will depend on the outcome of these studies and should be made in July 1977. The slow and intermediate speed pulsed power approaches to EBFA will be based on Proto I and Proto II results and several of the projected EBFA subsystems are presently being tested in Proto II. A further stage of power concentration, within the vacuum diode itself, would considerably ease the burden on dielectrics; methods of power multiplication involving magnetically imploded plasmas are being considered and tests have begun using the Ripple III apparatus

  8. The reactivity meter and core reactivity

    International Nuclear Information System (INIS)

    Siltanen, P.

    1999-01-01

    This paper discussed in depth the point kinetic equations and the characteristics of the point kinetic reactivity meter, particularly for large negative reactivities. From a given input signal representing the neutron flux seen by a detector, the meter computes a value of reactivity in dollars (ρ/β), based on inverse point kinetics. The prompt jump point of view is emphasised. (Author)

  9. Effects of pulse-to-pulse residual species on discharges in repetitively pulsed discharges through packed bed reactors

    Science.gov (United States)

    Kruszelnicki, Juliusz; Engeling, Kenneth W.; Foster, John E.; Kushner, Mark J.

    2016-09-01

    Atmospheric pressure dielectric barrier discharges (DBDs) sustained in packed bed reactors (PBRs) are being investigated for conversion of toxic and waste gases, and CO2 removal. These discharges are repetitively pulsed having varying flow rates and internal geometries, which results in species from the prior pulse still being in the discharge zone at the time the following discharge pulse occurs. A non-negligible residual plasma density remains, which effectively acts as preionization. This residual charge changes the discharge properties of subsequent pulses, and may impact important PBR properties such as chemical selectivity. Similarly, the residual neutral reactive species produced during earlier pulses will impact the reaction rates on subsequent pulses. We report on results of a computational investigation of a 2D PBR using the plasma hydrodynamics simulator nonPDPSIM. Results will be discussed for air flowing though an array of dielectric rods at atmospheric pressure. The effects of inter-pulse residual species on PBR discharges will be quantified. Means of controlling the presence of residual species in the reactor through gas flow rate, pulse repetition, pulse width and geometry will be described. Comparisons will be made to experiments. Work supported by US DOE Office of Fusion Energy Science and the National Science Foundation.

  10. PULSE COLUMN

    Science.gov (United States)

    Grimmett, E.S.

    1964-01-01

    This patent covers a continuous countercurrent liquidsolids contactor column having a number of contactor states each comprising a perforated plate, a layer of balls, and a downcomer tube; a liquid-pulsing piston; and a solids discharger formed of a conical section at the bottom of the column, and a tubular extension on the lowest downcomer terminating in the conical section. Between the conical section and the downcomer extension is formed a small annular opening, through which solids fall coming through the perforated plate of the lowest contactor stage. This annular opening is small enough that the pressure drop thereacross is greater than the pressure drop upward through the lowest contactor stage. (AEC)

  11. Pulse radiolysis

    International Nuclear Information System (INIS)

    Greenshields, H.; Seddon, W.A.

    1982-03-01

    This supplement to two bibliographies published in 1970 and 1972 lists 734 references to the literature of pulse radiolysis, arranged under eight broad subject headings. The references were compiled by searching Biological Abstracts, Chemical Abstracts, Nuclear Science Abstracts and the Weekly List of Papers in Radiation Chemistry issued by the Radiation Chemistry Data Center of Notre Dame University. Full bibliographic data is given for papers published in the period 1971 to 1974. A personal author index listing more than 600 authors and a similar number of co-authors is included

  12. Pulse pile-up. I: Short pulses

    International Nuclear Information System (INIS)

    Wilkinson, D.H.

    1990-07-01

    The search for rare large pulses against an intense background of smaller ones involves consideration of pulse pile-up. Approximate methods are presented, based on ruin theory, by which the probability of such pile-up may be estimated for pulses of arbitrary form and of arbitrary pulse-height distribution. These methods are checked against cases for which exact solutions are available. The present paper is concerned chiefly with short pulses of finite total duration. (Author) (5 refs., 24 figs.)

  13. Calculation of concentration profiles and their experimental verification with a pulsed sieve-plate column and the reactive material system of uranyl nitrate, nitric acid/tributyl phosphate, kerosine

    International Nuclear Information System (INIS)

    Ihle, E.

    1985-01-01

    The present study is concerned with the calculation of stationary and non-stationary concentration profiles as well as with the starting and disturbance behaviour of a pulsed sieve-plate extraction column. It investigates into the material system HNO 3 /uranyl nitrate in water with 30 per cent by volume of tributyl phosphate in kerosine. During the measurements of the concentration profiles for HNO 3 transition, which were effected in the direction of extraction and reextraction, it was shown that the concentration profiles measured in the mixer-settler range, in spite of a sixfold enlargement of the specific heat transfer area, do not differ essentially from those measured in the dispersion range. During the measurements of concentration profiles for HNO 3 /uranium transition, which were effected in the direction of coextraction and co-reextraction only for mixer-settler range, it was discovered that with increasing phase ratios, there is a depletion of the uranium concentration in the aqueous phase. If the phase ratio is further raised, it is the nitric acid, and not the uranium, that is depleted. (orig./PW) [de

  14. Reactivity estimation for subcritical and critical reactors

    International Nuclear Information System (INIS)

    Benhaim A; Bellino P; Gomez A

    2012-01-01

    We developed a digital reactimeter that works in both current and pulse mode. This reactimeter will allow to estimate the reactivity of the reactor at any state. We st obtained for the measurements taken in the experimental reactor RA-1 the reactivity around the critical state without a neutron source. Measurements were made using simultaneously a compensated ionization chamber and a 3He proportional counter. The results were compared with the ones obtained from the digital reactimeter of reference with matching results within the experimental errors (author)

  15. Temperature measurement of plasma-assisted flames: comparison between optical emission spectroscopy and 2-color laser induced fluorescence techniques

    KAUST Repository

    Lacoste, Deanna A.

    2015-03-30

    Accurate thermometry of highly reactive environments, such as plasma-assisted combustion, is challenging. With the help of conical laminar premixed methane-air flames, this study compares two thermometry techniques for the temperature determination in a combustion front enhanced by nanosecond repetitively pulsed (NRP) plasma discharges. Based on emission spectroscopic analysis, the results show that the rotational temperature of CH(A) gives a reasonable estimate for the adiabatic flame temperature, only for lean and stoichiometric conditions. The rotational temperature of N2(C) is found to significantly underestimate the flame temperature. The 2-color OH-PLIF technique gives correct values of the flame temperature.

  16. Temperature measurement of plasma-assisted flames: comparison between optical emission spectroscopy and 2-color laser induced fluorescence techniques

    KAUST Repository

    Lacoste, Deanna A.; Heitz, Sylvain A.; Moeck, Jonas P.

    2015-01-01

    Accurate thermometry of highly reactive environments, such as plasma-assisted combustion, is challenging. With the help of conical laminar premixed methane-air flames, this study compares two thermometry techniques for the temperature determination in a combustion front enhanced by nanosecond repetitively pulsed (NRP) plasma discharges. Based on emission spectroscopic analysis, the results show that the rotational temperature of CH(A) gives a reasonable estimate for the adiabatic flame temperature, only for lean and stoichiometric conditions. The rotational temperature of N2(C) is found to significantly underestimate the flame temperature. The 2-color OH-PLIF technique gives correct values of the flame temperature.

  17. Reactive Kripke semantics

    CERN Document Server

    Gabbay, Dov M

    2013-01-01

    This text offers an extension to the traditional Kripke semantics for non-classical logics by adding the notion of reactivity. Reactive Kripke models change their accessibility relation as we progress in the evaluation process of formulas in the model. This feature makes the reactive Kripke semantics strictly stronger and more applicable than the traditional one. Here we investigate the properties and axiomatisations of this new and most effective semantics, and we offer a wide landscape of applications of the idea of reactivity. Applied topics include reactive automata, reactive grammars, rea

  18. The experimental study of digital reactivity meter with space effect elimination

    International Nuclear Information System (INIS)

    Xie, Y.Q.; Jian, Z.B.; Zhang, Y.S.

    1988-01-01

    The paper summarizes a digital reactivity measurement theory with space effect elimination. On the basis of the theory, we have prepared an on-line digital reactivity meter with space effect elimination. This system is composed of neutron detector and magnifying, data acquisition channel, monoplate microprocessor and data output channel. Measured results of reactivity using the method described in this paper are in agreement with measured results of reactivity using the pulsed neutron method and 'ρ-shape' method within experimental error. (author)

  19. Reactive perforating collagenosis

    Directory of Open Access Journals (Sweden)

    Yadav Mukesh

    2009-01-01

    Full Text Available Reactive perforating collagenosis is a rare cutaneous disorder of unknown etiology. We hereby describe a case of acquired reactive perforating collagenosis in a patient of diabetes and chronic renal failure.

  20. Reactivity on the Web

    OpenAIRE

    Bailey, James; Bry, François; Eckert, Michael; Patrânjan, Paula Lavinia

    2005-01-01

    Reactivity, the ability to detect simple and composite events and respond in a timely manner, is an essential requirement in many present-day information systems. With the emergence of new, dynamic Web applications, reactivity on the Web is receiving increasing attention. Reactive Web-based systems need to detect and react not only to simple events but also to complex, real-life situations. This paper introduces XChange, a language for programming reactive behaviour on the Web,...

  1. Random pulse generator

    International Nuclear Information System (INIS)

    Guo Ya'nan; Jin Dapeng; Zhao Dixin; Liu Zhen'an; Qiao Qiao; Chinese Academy of Sciences, Beijing

    2007-01-01

    Due to the randomness of radioactive decay and nuclear reaction, the signals from detectors are random in time. But normal pulse generator generates periodical pulses. To measure the performances of nuclear electronic devices under random inputs, a random generator is necessary. Types of random pulse generator are reviewed, 2 digital random pulse generators are introduced. (authors)

  2. Monadic Functional Reactive Programming

    NARCIS (Netherlands)

    A.J. van der Ploeg (Atze); C Shan

    2013-01-01

    htmlabstractFunctional Reactive Programming (FRP) is a way to program reactive systems in functional style, eliminating many of the problems that arise from imperative techniques. In this paper, we present an alternative FRP formulation that is based on the notion of a reactive computation: a

  3. Programmable pulse generator

    International Nuclear Information System (INIS)

    Xue Zhihua; Lou Binqiao; Duan Xiaohui

    2002-01-01

    The author introduces the design of programmable pulse generator that is based on a micro-controller and controlled by RS232 interface of personal computer. The whole system has good stability. The pulse generator can produce TTL pulse and analog pulse. The pulse frequency can be selected by EPLD. The voltage amplitude and pulse width of analog pulse can be adjusted by analog switches and digitally-controlled potentiometers. The software development tools of computer is National Instruments LabView5.1. The front panel of this virtual instrumentation is intuitive and easy-to-use. Parameters can be selected and changed conveniently by knob and slide

  4. High-energy-throughput pulse compression by off-axis group-delay compensation in a laser-induced filament

    International Nuclear Information System (INIS)

    Voronin, A. A.; Alisauskas, S.; Muecke, O. D.; Pugzlys, A.; Baltuska, A.; Zheltikov, A. M.

    2011-01-01

    Off-axial beam dynamics of ultrashort laser pulses in a filament enable a radical energy-throughput improvement for filamentation-assisted pulse compression. We identify regimes where a weakly diverging wave, produced on the trailing edge of the pulse, catches up with a strongly diverging component, arising in the central part of the pulse, allowing sub-100-fs millijoule infrared laser pulses to be compressed to 20-25-fs pulse widths with energy throughputs in excess of 70%. Theoretical predictions have been verified by experimental results on filamentation-assisted compression of 70-fs, 1.5-μm laser pulses in high-pressure argon.

  5. Digital reactivity meter

    International Nuclear Information System (INIS)

    Akkus, B.; Anac, H.; Alsan, S.; Erk, S.

    1991-01-01

    Nowadays, various digital methods making use of microcomputers for neutron detector signals and determining the reactivity by numerical calculations are used in reactor control systems in place of classical reactivity meters. In this work, a calculation based on the ''The Time Dependent Transport Equation'' has been developed for determining the reactivity numerically. The reactivity values have been obtained utilizing a computer-based data acquisition and control system and compared with the analog reactivity meter values as well as the values calculated from the ''Inhour Equation''

  6. Method of controlling reactivity

    International Nuclear Information System (INIS)

    Tochihara, Hiroshi.

    1982-01-01

    Purpose: To improve the reactivity controlling characteristics by artificially controlling the leakage of neutron from a reactor and providing a controller for controlling the reactivity. Method: A reactor core is divided into several water gaps to increase the leakage of neutron, its reactivity is reduced, a gas-filled control rod or a fuel assembly is inserted into the gap as required, the entire core is coupled in a system to reduce the leakage of the neutron, and the reactivity is increased. The reactor shutdown is conducted by the conventional control rod, and to maintain critical state, boron density varying system is used together. Futher, a control rod drive is used with that similar to the conventional one, thereby enabling fast reactivity variation, and the positive reactivity can be obtained by the insertion, thereby improving the reactivity controlling characteristics. (Yoshihara, H.)

  7. Pulsed water jet generated by pulse multiplication

    Czech Academy of Sciences Publication Activity Database

    Dvorský, R.; Sitek, Libor; Sochor, T.

    2016-01-01

    Roč. 23, č. 4 (2016), s. 959-967 ISSN 1330-3651 R&D Projects: GA MŠk(CZ) LO1406; GA MŠk ED2.1.00/03.0082 Institutional support: RVO:68145535 Keywords : high- pressure pulses * pulse intensifier * pulsed water jet * water hammer effect Subject RIV: JQ - Machines ; Tools Impact factor: 0.723, year: 2016 http://hrcak.srce.hr/163752?lang=en

  8. Assistive Technology

    Science.gov (United States)

    ... Page Resize Text Printer Friendly Online Chat Assistive Technology Assistive technology (AT) is any service or tool that helps ... be difficult or impossible. For older adults, such technology may be a walker to improve mobility or ...

  9. Assisted Living

    Science.gov (United States)

    ... it, too. Back to top What is the Cost for Assisted Living? Although assisted living costs less than nursing home ... Primarily, older persons or their families pay the cost of assisted living. Some health and long-term care insurance policies ...

  10. Development of ultra-short high voltage pulse technology using magnetic pulse compression

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Byung Heon; Kim, S. G.; Nam, S. M.; Lee, B. C.; Lee, S. M.; Jeong, Y. U.; Cho, S. O.; Jin, J. T.; Choi, H. L

    1998-01-01

    The control circuit for high voltage switches, the saturable inductor for magnetic assist, and the magnetic pulse compression circuit were designed, constructed, and tested. The core materials of saturable inductors in magnetic pulse compression circuit were amorphous metal and ferrite and total compression stages were 3. By the test, in high repetition rate, high pulse compression were certified. As a result of this test, it became possible to increase life-time of thyratrons and to replace thyratrons by solid-state semiconductor switches. (author). 16 refs., 16 tabs.

  11. Development of ultra-short high voltage pulse technology using magnetic pulse compression

    International Nuclear Information System (INIS)

    Cha, Byung Heon; Kim, S. G.; Nam, S. M.; Lee, B. C.; Lee, S. M.; Jeong, Y. U.; Cho, S. O.; Jin, J. T.; Choi, H. L.

    1998-01-01

    The control circuit for high voltage switches, the saturable inductor for magnetic assist, and the magnetic pulse compression circuit were designed, constructed, and tested. The core materials of saturable inductors in magnetic pulse compression circuit were amorphous metal and ferrite and total compression stages were 3. By the test, in high repetition rate, high pulse compression were certified. As a result of this test, it became possible to increase life-time of thyratrons and to replace thyratrons by solid-state semiconductor switches. (author). 16 refs., 16 tabs

  12. Laser pulse stacking method

    Science.gov (United States)

    Moses, E.I.

    1992-12-01

    A laser pulse stacking method is disclosed. A problem with the prior art has been the generation of a series of laser beam pulses where the outer and inner regions of the beams are generated so as to form radially non-synchronous pulses. Such pulses thus have a non-uniform cross-sectional area with respect to the outer and inner edges of the pulses. The present invention provides a solution by combining the temporally non-uniform pulses in a stacking effect to thus provide a more uniform temporal synchronism over the beam diameter. 2 figs.

  13. Pulse to pulse klystron diagnosis system

    International Nuclear Information System (INIS)

    Nowak, J.; Davidson, V.; Genova, L.; Johnson, R.; Reagan, D.

    1981-03-01

    This report describes a system used to study the behavior of SLAC high powered klystrons operating with a twice normal pulse width of 5 μs. At present, up to eight of the klystrons installed along the accelerator can be operated with long pulses and monitored by this system. The report will also discuss some of the recent findings and investigations

  14. Electron emitter pulsed-type cylindrical IEC

    International Nuclear Information System (INIS)

    Miley, G.H.; Gu, Y.; Stubbers, R.; Zich, R.; Anderl, R.; Hartwell, J.

    1997-01-01

    A cylindrical version of the single grid Inertial Electrostatic Confinement (IEC) device (termed the C-device) has been developed for use as a 2.5-MeV D-D fusion neutron source for neutron activation analysis. The C-device employs a hollow-tube type cathode with similar anodes backed up by ''reflector'' dishes. The resulting discharge differs from a conventional hollow cathode discharge, by creating an explicit ion beam which is ''pinched'' in the cathode region. Resulting fusion reactions generate ∼10 6 neutron/s. A pulsed version is under development for applications requiring higher fluxes. Several pulsing techniques are under study, including an electron emitter (e-emitter) assisted discharge in a thorated tungsten wire emitter located behind a slotted area in the reflector dishes. Pulsing is initiated after establishing a low power steady-state discharge by pulsing the e-emitter current using a capacitor switch type circuit. The resulting electron jet, coupled with the discharge by the biased slot array, creates a strong pulse in the pinched ion beam. The pulse length/repetition rate are controlled by the e-emitter pulse circuit. Typical parameters in present studies are ∼30micros, 10Hz and 1-amp ion current. Corresponding neutron measurements are an In-foil type activation counter for time averaged rates. Results for a wide variety of operating conditions are presented

  15. Reactive Programming in Java

    CERN Document Server

    CERN. Geneva

    2017-01-01

    Reactive Programming in gaining a lot of excitement. Many libraries, tools, and frameworks are beginning to make use of reactive libraries. Besides, applications dealing with big data or high frequency data can benefit from this programming paradigm. Come to this presentation to learn about what reactive programming is, what kind of problems it solves, how it solves them. We will take an example oriented approach to learning the programming model and the abstraction.

  16. BN600 reactivity definition

    International Nuclear Information System (INIS)

    Zheltyshev, V.; Ivanov, A.

    2000-01-01

    Since 1980, the fast BN600 reactor with sodium coolant has been operated at Beloyarsk Nuclear Power Plant. The periodic monitoring of the reactivity modifications should be implemented in compliance with the standards and regulations applied in nuclear power engineering. The reactivity measurements are carried out in order to confirm the basic neutronic features of a BN600 reactor. The reactivity measurements are aimed to justify that nuclear safety is provided in course of the in-reactor installation of the experimental core components. Two reactivity meters are to be used on BN600 operation: 1. Digital on-line reactivity calculated under stationary reactor operation on power (approximation of the point-wise kinetics is applied). 2. Second reactivity meter used to define the reactor control rod operating components efficiency under reactor startup and take account of the changing efficiency of the sensor, however, this is more time-consumptive than the on-line reactivity meter. The application of two reactivity meters allows for the monitoring of the reactor reactivity under every operating mode. (authors)

  17. Neural network and area method interpretation of pulsed experiments

    Energy Technology Data Exchange (ETDEWEB)

    Dulla, S.; Picca, P.; Ravetto, P. [Politecnico di Torino, Dipartimento di Energetica, Corso Duca degli Abruzzi, 24 - 10129 Torino (Italy); Canepa, S. [Lab of Reactor Physics and Systems Behaviour LRS, Paul Scherrer Inst., 5232 Villigen (Switzerland)

    2012-07-01

    The determination of the subcriticality level is an important issue in accelerator-driven system technology. The area method, originally introduced by N. G. Sjoestrand, is a classical technique to interpret flux measurement for pulsed experiments in order to reconstruct the reactivity value. In recent times other methods have also been developed, to account for spatial and spectral effects, which were not included in the area method, since it is based on the point kinetic model. The artificial neural network approach can be an efficient technique to infer reactivities from pulsed experiments. In the present work, some comparisons between the two methods are carried out and discussed. (authors)

  18. Pulsed dc self-sustained magnetron sputtering

    International Nuclear Information System (INIS)

    Wiatrowski, A.; Posadowski, W. M.; Radzimski, Z. J.

    2008-01-01

    The magnetron sputtering has become one of the commonly used techniques for industrial deposition of thin films and coatings due to its simplicity and reliability. At standard magnetron sputtering conditions (argon pressure of ∼0.5 Pa) inert gas particles (necessary to sustain discharge) are often entrapped in the deposited films. Inert gas contamination can be eliminated during the self-sustained magnetron sputtering (SSS) process, where the presence of the inert gas is not a necessary requirement. Moreover the SSS process that is possible due to the high degree of ionization of the sputtered material also gives a unique condition during the transport of sputtered particles to the substrate. So far it has been shown that the self-sustained mode of magnetron operation can be obtained using dc powering (dc-SSS) only. The main disadvantage of the dc-SSS process is its instability related to random arc formation. In such case the discharge has to be temporarily extinguished to prevent damaging both the magnetron source and power supply. The authors postulate that pulsed powering could protect the SSS process against arcs, similarly to reactive pulsed magnetron deposition processes of insulating thin films. To put this concept into practice, (i) the high enough plasma density has to be achieved and (ii) the type of pulsed powering has to be chosen taking plasma dynamics into account. In this article results of pulsed dc self-sustained magnetron sputtering (pulsed dc-SSS) are presented. The planar magnetron equipped with a 50 mm diameter and 6 mm thick copper target was used during the experiments. The maximum target power was about 11 kW, which corresponded to the target power density of ∼560 W/cm 2 . The magnetron operation was investigated as a function of pulse frequency (20-100 kHz) and pulse duty factor (50%-90%). The discharge (argon) extinction pressure level was determined for these conditions. The plasma emission spectra (400-410 nm range) and deposition

  19. Steady State versus Pulsed Tokamak DEMO

    Energy Technology Data Exchange (ETDEWEB)

    Orsitto, F.P., E-mail: francesco.orsitto@enea.it [Associazione EURATOM-ENEA Unita Tecnica Fusione, Frascati (Italy); Todd, T. [CCFE/Fusion Association, Culham Science Centre, Abingdon (United Kingdom)

    2012-09-15

    Full text: The present report deals with a Review of problems for a Steady state(SS) DEMO, related argument is treated about the models and the present status of comparison between the characteristics of DEMO pulsed versus a Steady state device.The studied SS DEMO Models (SLIM CS, PPCS model C EU-DEMO, ARIES-RS) are analyzed from the point of view of the similarity scaling laws and critical issues for a steady state DEMO. A comparison between steady state and pulsed DEMO is therefore carried out: in this context a new set of parameters for a pulsed (6 - 8 hours pulse) DEMO is determined working below the density limit, peak temperature of 20 keV, and requiring a modest improvement in the confinement factor(H{sub IPBy2} = 1.1) with respect to the H-mode. Both parameters density and confinement parameter are lower than the DEMO models presently considered. The concept of partially non-inductive pulsed DEMO is introduced since a pulsed DEMO needs heating and current drive tools for plasma stability and burn control. The change of the main parameter design for a DEMO working at high plasma peak temperatures T{sub e} {approx} 35 keV is analyzed: in this range the reactivity increases linearly with temperature, and a device with smaller major radius (R = 7.5 m) is compatible with high temperature. Increasing temperature is beneficial for current drive efficiency and heat load on divertor, being the synchrotron radiation one of the relevant components of the plasma emission at high temperatures and current drive efficiency increases with temperature. Technology and engineering problems are examined including efficiency and availability R&D issues for a high temperature DEMO. Fatigue and creep-fatigue effects of pulsed operations on pulsed DEMO components are considered in outline to define the R&D needed for DEMO development. (author)

  20. Pulsed-DC selfsputtering of copper

    International Nuclear Information System (INIS)

    Wiatrowski, A; Posadowski, W M; Radzimski, Z J

    2008-01-01

    At standard magnetron sputtering conditions (argon pressure ∼0.5 Pa) inert gas particles are often entrapped in the formed films. Inert gas contamination can be eliminated by using the self-sustained magnetron sputtering process because it is done in the absence of the inert gas atmosphere. The self-sustained sputtering (SSS) gives also a unique condition during the transport of sputtered particles to the substrate. It is especially useful for filling high aspect ratio submicron scale structures for microelectronics. So far it has been shown that the self-sputtering process can be sustained in the DC operation mode (DC-SSS) only. The main disadvantage of DC-SSS process is instability related to possible arc formation. Usage of pulsed sputtering, similarly to reactive pulsed magnetron sputtering, could eliminate this problem. In this paper results of pulsed-DC self-sustained magnetron sputtering (pulsed DC-SSS) of copper are presented for the first time. The planar magnetron equipped with a 50 mm in diameter and 6 mm thick copper target was powered by DC-power supply modulated by power switch. The maximum target power was about 11 kW (∼550W/cm 2 ). The magnetron operation was investigated as a function of pulsing frequency (20-100 kHz) and duty factor (50-90%). The discharge extinction pressure was determined for these conditions. The plasma emission spectra (400-410nm range) and deposition rates were observed for both DC and pulsed DC sustained self-sputtering processes. The presented results illustrate that stable pulsed DC-SSS process can be obtained at pulsing frequency in the range of 60-100 kHz and duty factor of 70-90%

  1. Pulsed-DC selfsputtering of copper

    Science.gov (United States)

    Wiatrowski, A.; Posadowski, W. M.; Radzimski, Z. J.

    2008-03-01

    At standard magnetron sputtering conditions (argon pressure ~0.5 Pa) inert gas particles are often entrapped in the formed films. Inert gas contamination can be eliminated by using the self-sustained magnetron sputtering process because it is done in the absence of the inert gas atmosphere. The self-sustained sputtering (SSS) gives also a unique condition during the transport of sputtered particles to the substrate. It is especially useful for filling high aspect ratio submicron scale structures for microelectronics. So far it has been shown that the self-sputtering process can be sustained in the DC operation mode (DC-SSS) only. The main disadvantage of DC-SSS process is instability related to possible arc formation. Usage of pulsed sputtering, similarly to reactive pulsed magnetron sputtering, could eliminate this problem. In this paper results of pulsed-DC self-sustained magnetron sputtering (pulsed DC-SSS) of copper are presented for the first time. The planar magnetron equipped with a 50 mm in diameter and 6 mm thick copper target was powered by DC-power supply modulated by power switch. The maximum target power was about 11 kW (~550W/cm2). The magnetron operation was investigated as a function of pulsing frequency (20-100 kHz) and duty factor (50-90%). The discharge extinction pressure was determined for these conditions. The plasma emission spectra (400-410nm range) and deposition rates were observed for both DC and pulsed DC sustained self-sputtering processes. The presented results illustrate that stable pulsed DC-SSS process can be obtained at pulsing frequency in the range of 60-100 kHz and duty factor of 70-90%.

  2. Electrospinning of reactive mesogens

    NARCIS (Netherlands)

    Yao, J.; Picot, O.T.; Hughes-Brittain, N.F.; Bastiaansen, C.W.M.; Peijs, T.

    2016-01-01

    The reinforcement potential of reactive liquid crystals or reactive mesogens (RMs) in electrospun fibers was investigated through the blending of two types of RMs (RM257 and RM82) with two types of thermoplastics; polyamide 6 (PA6) and poly(methyl methacrylate) (PMMA). Polymer/RM blends were

  3. Pulse radiolysis studies of fast reactions in molecular systems. Progress report, November 1976--October 1977

    International Nuclear Information System (INIS)

    Dorfman, L.M.

    1977-01-01

    Results from research in the following two areas are given: formation, properties, and reactivity of molecular ionic species in irradiated liquid systems; and pulse radiolysis of elementary reactions in protein function

  4. Laser pulse heating of nuclear fuels for simulation of reactor power

    Indian Academy of Sciences (India)

    Laser applications; nuclear fuel elements; nuclear safety. ... accident (LOCA) and reactivity initiated accident (RIA), a laser pulse heating system is under ... As a prelude to work on irradiated nuclear fuel specimens, pilot studies on unirradiated ...

  5. Aplicação da metodologia da assistência a pacientes com Lúpus Eritematoso Sistêmico em pulsoterapia: uma experiência docente Uso de la metodología de la asistencia a pacientes con Lupus Eritematoso Sistémico en quimioterapia por pulso: una experiencia de enseñanza Application of assistance methodology in patients suffering Systemic Erythematosus Lupus in drug pulse therapy: a teaching experience

    Directory of Open Access Journals (Sweden)

    Maria Gorette dos Reis

    2007-04-01

    éncia ofrecidas por los servícios públicos de salud.This research is an experience report of clinical teaching for undergraduate nursing students, to whom it was used the assistance methodology as a teaching strategy. It was applied in adults, sufferingSystemic Erythematosus Lupus, young women, in majority, who were submitted to drug pulse therapy, a therapeutic modality which, through immunesuppression, reduces the inflammatory process caused by selfantibody. This way, the assistance is systemized, individualized and integral and it allows single opportunities of theoric-pratic correlation for the students, with the application of basic knowledge of the formation area, context of the health-disease process and the focus going beyond the biologic, including emotional, social and spiritual aspects and opportunities for the student to evaluate several factors that interfere in the assistance conditions offered by public health services.

  6. Reactively loaded arrays based on overlapping sub-arrays with flat-top radiation pattern

    NARCIS (Netherlands)

    Maximidis, R. T.; Smolders, A. B.; Toso, G.; Caratelli, D.

    2017-01-01

    The design of reactively-loaded antenna arrays featuring a pulse-shaped radiation pattern for limited scan-angle applications is presented. The use of the reactive loading allows reducing the complexity of the feeding structure, eliminating the need for complex overlapping beam-forming networks and

  7. Safety aspects of pulsed YAYOI and Japan Linac Booster

    International Nuclear Information System (INIS)

    An, S.; Oka, Y.; Wakabayashi, J.

    1976-01-01

    The paper consists of two parts. The first part is concerned with safety aspects of pulsed YAYOI. Reactivity pulsed operation of YAYOI is performed with reactivity oscillating devices. Inherent safety characteristics due to dilation of metal fuel, a small amount of f.p. build up, reactor operation preserving fuel integrity and experience on transient experiments are the principal basis for safety assurance. Conditions for pulsed operation, namely, maximum allowable temperature, maximum number of repetition of pulsed operation and so on are derived from the consideration on the integrity of fuel. Instrumentation and control systems are reinforced by displacement meter in the core, interlock system, special timer for pulsed operation, additional scram conditions and reactivity meter. Accident analysis and safety evaluation indicate the conservative safety features of the facility. Concerning pulsed operation of YAYOI combined with Linac, special attention must be given to the design of Linac target placed in the core. In the second part are described the principal guide-lines and basic ideas for safety design of Japan Linac Booster (JLB). JLB is a U-Mo fueled and sodium cooled fast reactor with rotating reflector and Linac target in the core. The pulsed neutrons are injected into the core coincidentally with repetitive peaks of reactivity. Design of rotating reflector and Linac target system are the new and important safety problems not yet encountered in the usual sodium fast reactor design. The axis of the rotating reflector is horizontal, which avoids the collision of reflector block with core in the case of failure of rotating reflector. The separate cooling channels for target and the Linac electron beam control system are provided. Reactor shut down and power control systems must be carefully designed. Core meltdown and disassembly accident is considered as a hypothetical accident which is a basis for containment system design. (auth.)

  8. Ultrashort X-ray pulse science

    Energy Technology Data Exchange (ETDEWEB)

    Chin, Alan Hap [Univ. of California, Berkeley, CA (US). Dept. of Physics; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    1998-05-01

    A variety of phenomena involves atomic motion on the femtosecond time-scale. These phenomena have been studied using ultrashort optical pulses, which indirectly probe atomic positions through changes in optical properties. Because x-rays can more directly probe atomic positions, ultrashort x-ray pulses are better suited for the study of ultrafast structural dynamics. One approach towards generating ultrashort x-ray pulses is by 90° Thomson scattering between terawatt laser pulses and relativistic electrons. Using this technique, the author generated ~ 300 fs, 30 keV (0.4 Å) x-ray pulses. These x-ray pulses are absolutely synchronized with ultrashort laser pulses, allowing femtosecond optical pump/x-ray probe experiments to be performed. Using the right-angle Thomson scattering x-ray source, the author performed time-resolved x-ray diffraction studies of laser-perturbated InSb. These experiments revealed a delayed onset of lattice expansion. This delay is due to the energy relaxation from a dense electron-hole plasma to the lattice. The dense electron-hole plasma first undergoes Auger recombination, which reduces the carrier concentration while maintaining energy content. Longitudinal-optic (LO) phonon emission then couples energy to the lattice. LO phonon decay into acoustic phonons, and acoustic phonon propagation then causes the growth of a thermally expanded layer. Source characterization is instrumental in utilizing ultrashort x-ray pulses in time-resolved x-ray spectroscopies. By measurement of the electron beam diameter at the generation point, the pulse duration of the Thomson scattered x-rays is determined. Analysis of the Thomson scattered x-ray beam properties also provides a novel means of electron bunch characterization. Although the pulse duration is inferred for the Thomson scattering x-ray source, direct measurement is required for other x-ray pulse sources. A method based on the laser-assisted photoelectric effect (LAPE) has been demonstrated as a

  9. Ultrashort X-ray pulse science

    International Nuclear Information System (INIS)

    Chin, A.H.; Lawrence Berkeley National Lab., CA

    1998-01-01

    A variety of phenomena involves atomic motion on the femtosecond time-scale. These phenomena have been studied using ultrashort optical pulses, which indirectly probe atomic positions through changes in optical properties. Because x-rays can more directly probe atomic positions, ultrashort x-ray pulses are better suited for the study of ultrafast structural dynamics. One approach towards generating ultrashort x-ray pulses is by 90 o Thomson scattering between terawatt laser pulses and relativistic electrons. Using this technique, the author generated ∼ 300 fs, 30 keV (0.4 (angstrom)) x-ray pulses. These x-ray pulses are absolutely synchronized with ultrashort laser pulses, allowing femtosecond optical pump/x-ray probe experiments to be performed. Using the right-angle Thomson scattering x-ray source, the author performed time-resolved x-ray diffraction studies of laser-perturbated InSb. These experiments revealed a delayed onset of lattice expansion. This delay is due to the energy relaxation from a dense electron-hole plasma to the lattice. The dense electron-hole plasma first undergoes Auger recombination, which reduces the carrier concentration while maintaining energy content. Longitudinal-optic (LO) phonon emission then couples energy to the lattice. LO phonon decay into acoustic phonons, and acoustic phonon propagation then causes the growth of a thermally expanded layer. Source characterization is instrumental in utilizing ultrashort x-ray pulses in time-resolved x-ray spectroscopies. By measurement of the electron beam diameter at the generation point, the pulse duration of the Thomson scattered x-rays is determined. Analysis of the Thomson scattered x-ray beam properties also provides a novel means of electron bunch characterization. Although the pulse duration is inferred for the Thomson scattering x-ray source, direct measurement is required for other x-ray pulse sources. A method based on the laser-assisted photoelectric effect (LAPE) has been

  10. International assistance. Licensing assistance project

    International Nuclear Information System (INIS)

    Aleev, A.

    1999-01-01

    Description of licensing assistance project for VATESI is presented. In licensing of unit No.1 of INPP VATESI is supported by many western countries. Experts from regulatory bodies or scientific organizations of those countries assist VATESI staff in reviewing documentation presented by INPP. Among bilateral cooperation support is provided by European Commission through Phare programme

  11. Digital reactivity meter

    International Nuclear Information System (INIS)

    Jiang Zongbing

    1996-02-01

    The importance and the usual methods of reactivity measurement in a nuclear reactor are presented. Emphasis is put upon the calculation principle, software and hardware components, main specifications, application, as well as the features of the digital reactivity meter. The test results of operation in various reactors shown that the meter possess the following features: high accuracy, short response time, low output noise, high resolution, wide measuring range, simple and flexible to operate, high stability and reliability. In addition, the reactivity meter can save the measuring data automatically and have a perfect capability of self-verifying. It not only meet the requirement of the reactivity measurement in nuclear power plant, but also can be applied to various types of reactors. (1 tab.)

  12. Stress Reactivity in Insomnia.

    Science.gov (United States)

    Gehrman, Philip R; Hall, Martica; Barilla, Holly; Buysse, Daniel; Perlis, Michael; Gooneratne, Nalaka; Ross, Richard J

    2016-01-01

    This study examined whether individuals with primary insomnia (PI) are more reactive to stress than good sleepers (GS). PI and GS (n = 20 per group), matched on gender and age, completed three nights of polysomnography. On the stress night, participants received a mild electric shock and were told they could receive additional shocks during the night. Saliva samples were obtained for analysis of cortisol and alpha amylase along with self-report and visual analog scales (VAS). There was very little evidence of increased stress on the stress night, compared to the baseline night. There was also no evidence of greater stress reactivity in the PI group for any sleep or for salivary measures. In the GS group, stress reactivity measured by VAS scales was positively associated with an increase in sleep latency in the experimental night on exploratory analyses. Individuals with PI did not show greater stress reactivity compared to GS.

  13. Structure, Reactivity and Dynamics

    Indian Academy of Sciences (India)

    Understanding structure, reactivity and dynamics is the core issue in chemical ... functional theory (DFT) calculations, molecular dynamics (MD) simulations, light- ... between water and protein oxygen atoms, the superionic conductors which ...

  14. Taskable Reactive Agent Communities

    National Research Council Canada - National Science Library

    Myers, Karen

    2002-01-01

    The focus of Taskable Reactive Agent Communities (TRAC) project was to develop mixed-initiative technology to enable humans to supervise and manage teams of agents as they perform tasks in dynamic environments...

  15. Reactive sputter deposition

    CERN Document Server

    Mahieu, Stijn

    2008-01-01

    In this valuable work, all aspects of the reactive magnetron sputtering process, from the discharge up to the resulting thin film growth, are described in detail, allowing the reader to understand the complete process. Hence, this book gives necessary information for those who want to start with reactive magnetron sputtering, understand and investigate the technique, control their sputtering process and tune their existing process, obtaining the desired thin films.

  16. Ultrashort Laser Pulse Phenomena

    CERN Document Server

    Diels, Jean-Claude

    2006-01-01

    Ultrashort Laser Pulse Phenomena, 2e serves as an introduction to the phenomena of ultra short laser pulses and describes how this technology can be used to examine problems in areas such as electromagnetism, optics, and quantum mechanics. Ultrashort Laser Pulse Phenomena combines theoretical backgrounds and experimental techniques and will serve as a manual on designing and constructing femtosecond (""faster than electronics"") systems or experiments from scratch. Beyond the simple optical system, the various sources of ultrashort pulses are presented, again with emphasis on the basic

  17. Pulse radiolysis of 9,10-anthraquinone in methanol

    International Nuclear Information System (INIS)

    Mayer, J.; Krasiukianis, R.

    1990-01-01

    The reactions of anthraquinone with intermediates in methanol (e 2 - , . CH 2 O - , . CH 2 OH) were investigated using γ-radiolysis and pulse radiolysis method. The anthraquinone radical anions are reactive towards O 2 (ca 3 x 10 8 mol -1 dm 3 s -1 ) and can disproportionate giving corresponding dianion. (author)

  18. Reactive power compensator

    Science.gov (United States)

    El-Sharkawi, Mohamed A.; Venkata, Subrahmanyam S.; Chen, Mingliang; Andexler, George; Huang, Tony

    1992-01-01

    A system and method for determining and providing reactive power compensation for an inductive load. A reactive power compensator (50,50') monitors the voltage and current flowing through each of three distribution lines (52a, 52b, 52c), which are supplying three-phase power to one or more inductive loads. Using signals indicative of the current on each of these lines when the voltage waveform on the line crosses zero, the reactive power compensator determines a reactive power compensator capacitance that must be connected to the lines to maintain a desired VAR level, power factor, or line voltage. Alternatively, an operator can manually select a specific capacitance for connection to each line, or the capacitance can be selected based on a time schedule. The reactive power compensator produces control signals, which are coupled through optical fibers (102/106) to a switch driver (110, 110') to select specific compensation capacitors (112) for connections to each line. The switch driver develops triggering signals that are supplied to a plurality of series-connected solid state switches (350), which control charge current in one direction in respect to ground for each compensation capacitor. During each cycle, current flows from ground to charge the capacitors as the voltage on the line begins to go negative from its positive peak value. The triggering signals are applied to gate the solid state switches into a conducting state when the potential on the lines and on the capacitors reaches a negative peak value, thereby minimizing both the potential difference and across the charge current through the switches when they begin to conduct. Any harmonic distortion on the potential and current carried by the lines is filtered out from the current and potential signals used by the reactive power compensator so that it does not affect the determination of the required reactive compensation.

  19. Reactive power compensator

    Energy Technology Data Exchange (ETDEWEB)

    El-Sharkawi, Mohamed A. (Renton, WA); Venkata, Subrahmanyam S. (Woodinville, WA); Chen, Mingliang (Kirkland, WA); Andexler, George (Everett, WA); Huang, Tony (Seattle, WA)

    1992-01-01

    A system and method for determining and providing reactive power compensation for an inductive load. A reactive power compensator (50,50') monitors the voltage and current flowing through each of three distribution lines (52a, 52b, 52c), which are supplying three-phase power to one or more inductive loads. Using signals indicative of the current on each of these lines when the voltage waveform on the line crosses zero, the reactive power compensator determines a reactive power compensator capacitance that must be connected to the lines to maintain a desired VAR level, power factor, or line voltage. Alternatively, an operator can manually select a specific capacitance for connection to each line, or the capacitance can be selected based on a time schedule. The reactive power compensator produces control signals, which are coupled through optical fibers (102/106) to a switch driver (110, 110') to select specific compensation capacitors (112) for connections to each line. The switch driver develops triggering signals that are supplied to a plurality of series-connected solid state switches (350), which control charge current in one direction in respect to ground for each compensation capacitor. During each cycle, current flows from ground to charge the capacitors as the voltage on the line begins to go negative from its positive peak value. The triggering signals are applied to gate the solid state switches into a conducting state when the potential on the lines and on the capacitors reaches a negative peak value, thereby minimizing both the potential difference and across the charge current through the switches when they begin to conduct. Any harmonic distortion on the potential and current carried by the lines is filtered out from the current and potential signals used by the reactive power compensator so that it does not affect the determination of the required reactive compensation.

  20. A digital instrument for reactivity measurements in a nuclear reactor

    International Nuclear Information System (INIS)

    Chwaszczewski, S.

    1979-01-01

    An instrument for digital determination of the reactivity in nuclear reactors is described. It is based on the CAMAC standard apparatus, suitable for the use of pulse or current type neutron detectors and operates with prompt response and an output signal proportional to the core neutron flux. The measured data of neutron flux and reactivity can be registered by a digital display unit, an indicator, or, by request of the operator, a paper type punch. The algorithms used for reactivity calculation are considered and the results of numerical studies on those algorithms are discussed. The instrument has been used for determining the reactivity of the control elements in the fast-thermal assembly ANNA and in the research reactor MARIA. Some results of these measurements are given. (author)

  1. Digital instrument for reactivity measurements in a nuclear reactor

    Energy Technology Data Exchange (ETDEWEB)

    Chwaszczewski, S [Institute of Nuclear Research, Warsaw (Poland)

    1979-07-01

    An instrument for digital determination of the reactivity in nuclear reactors is described. It is based on the CAMAC standard apparatus, suitable for the use of pulse or current type neutron detectors and operates with prompt response and an output signal proportional to the core neutron flux. The measured data of neutron flux and reactivity can be registered by a digital display unit, an indicator, or, by request of the operator, a paper type punch. The algorithms used for reactivity calculation are considered and the results of numerical studies on those algorithms are discussed. The instrument has been used for determining the reactivity of the control elements in the fast-thermal assembly ANNA and in the research reactor MARIA. Some results of these measurements are given.

  2. Gas phase pulse radiolysis

    International Nuclear Information System (INIS)

    Jonah, C.D.; Andong Liu; Mulac, W.A.

    1987-01-01

    Gas phase pulse radiolysis, a technique which can be used to study many different phenomena in chemistry and physics, is discussed. As a source of small radicals, pulse radiolysis is important to the field of chemistry, particularly to combustion and atmospheric kinetics. The reactions of 1,3-butadiene, allene, ethylene and acetylene with OH are presented. 52 refs., 1 fig., 1 tab

  3. Pulse duration discriminator

    International Nuclear Information System (INIS)

    Kosakovskij, L.F.

    1980-01-01

    Basic circuits of a discriminator for discrimination of pulses with the duration greater than the preset one, and of a multifunctional discriminator allowing to discriminate pulses with the duration greater (tsub(p)>tsub(s)) and lesser (tsub(p) tsub(s) and with the duration tsub(p) [ru

  4. Sources of pulsed radiation

    International Nuclear Information System (INIS)

    Sauer, M.C. Jr.

    1981-01-01

    Characteristics of various sources of pulsed radiation are examined from the viewpoint of their importance to the radiation chemist, and some examples of uses of such sources are mentioned. A summary is given of the application of methods of physical dosimetry to pulsed sources, and the calibration of convenient chemical dosimeters by physical dosimetry is outlined. 7 figures, 1 table

  5. Pulsed neutron generator

    International Nuclear Information System (INIS)

    Bespalov, D.F.; Bykovskii, Yu.A.; Vergun, I.I.; Kozlovskii, K.I.; Kozyrev, Yu.P.; Leonov, R.K.; Simagin, B.I.; Tsybin, A.S.; Shikanov, A.Ie.

    1986-03-01

    The paper describes a new device for generating pulsed neutron fields, utilized in nuclear geophysics for carrying out pulsed neutron logging and activation analysis under field conditions. The invention employs a sealed-off neutron tube with a laser ion source which increases neutron yield to the level of 10 neutrons per second or higher. 2 refs., 1 fig

  6. Bipolar pulse generator for intense pulsed ion beam accelerator

    International Nuclear Information System (INIS)

    Ito, H.; Igawa, K.; Kitamura, I.; Masugata, K.

    2007-01-01

    A new type of pulsed ion beam accelerator named ''bipolar pulse accelerator'' (BPA) has been proposed in order to improve the purity of intense pulsed ion beams. To confirm the principle of the BPA, we developed a bipolar pulse generator for the bipolar pulse experiment, which consists of a Marx generator and a pulse forming line (PFL) with a rail gap switch on its end. In this article, we report the first experimental result of the bipolar pulse and evaluate the electrical characteristics of the bipolar pulse generator. When the bipolar pulse generator was operated at 70% of the full charge condition of the PFL, the bipolar pulse with the first (-138 kV, 72 ns) and the second pulse (+130 kV, 70 ns) was successfully obtained. The evaluation of the electrical characteristics indicates that the developed generator can produce the bipolar pulse with fast rise time and sharp reversing time

  7. Pulse induction heating

    Energy Technology Data Exchange (ETDEWEB)

    Vasiliev, A S; Kachanov, B Y; Kogan, B V

    1993-12-31

    Induction heating and three types of pulse processes were studied. It was found that in pulse processes the frequency and pulse duration of heat treatments do not remain constant. High frequency pulse heat treatments can be used on sprayed coatings; such treatments will result in stronger surfaces with no cracks. For induction hardening, the rate of specific power was 1 to 1.5 kW/sq.cm, for forging it was 0.2 to 0.3 kW/sq.cm and for melting it was 0.05 to 0.1 kW/sq.cm. The application of pulse heating will result in higher rates of specific power.

  8. Transcanalicular laser-assisted dacryocystorhinostomy.

    Science.gov (United States)

    Rosen, N; Barak, A; Rosner, M

    1997-09-01

    Current techniques of laser-assisted dacryocystorhinostomy are mostly endonasal. In this report, the authors describe their technique of laser-assisted dacryocystorhinostomy performed through the canaliculi and the surgical results they achieved. Fourteen patients with nasolacrimal duct obstruction underwent transcanalicular laser-assisted dacryocystorhinostomy. The bony ostium was perforated using a fiber optic-transmitting, giant-pulse Nd:YAG laser, with an energy of 0.5 to 4 J per pulse. The total energy used to create an ostium was 18 to 34 J. A silicone tube was inserted through the canaliculi and the ostium into the nasal cavity and kept in place for 5 to 7 months. Patients were observed for 18 to 22 months. Nine of the 14 patients (64%) reported the disappearance of epiphora following surgery. In 3 patients, no relief of epiphora was obtained. In 1 patient the operation was not completed because of severe nasal bleeding. In another, tearing began 12 months after surgery (6 months after tube removal). Transcanalicular laser-assisted dacryocystorhinostomy is a potentially useful method for performing dacryocystorhinostomy. Technical modifications and improvements are needed to increase the success rate.

  9. Digital reactivity meter

    International Nuclear Information System (INIS)

    Copie, M.; Valantic, B.

    1978-01-01

    Digital reactivity meters (DRM) are mostly used as measuring instruments, e.g. for calibration of control rods, and there are only a few cases of their incorporation into the control systems of the reactors. To move in this direction there is more development work needed. First of all, fast algorithms are needed for inverse kinetics equations to relieve the computer for more important tasks of reactor model solving in real time. The next problem, currently under investigation, is the incorporation of the reactor thermal-hydraulic model into the DRM so that it can be used in the power range. Such an extension of DHM allows presentation not only of the instantaneous reactivity of the system, but also the inserted reactivity can be estimated from the temperature reactivity feed-backs. One of the applications of this concept is the anomalous digital reactivity monitor (ADRN) as part of the reactor protection system. As a solution of the first problem, a fast algorithm for solving the inverse kinetics equations has been implemented in the off-line program RODCAL on CDC 1700 computer and tested for its accuracy by performing different control rod calibrations on the reactor TRIGA

  10. Pulse Distortion in Saturated Fiber Optical Parametric Chirped Pulse Amplification

    DEFF Research Database (Denmark)

    Lali-Dastjerdi, Zohreh; Da Ros, Francesco; Rottwitt, Karsten

    2012-01-01

    Fiber optical parametric chirped pulse amplification is experimentally compared for different chirped pulses in the picosecond regime. The amplified chirped pulses show distortion appearing as pedestals after recompression when the amplifier is operated in saturation.......Fiber optical parametric chirped pulse amplification is experimentally compared for different chirped pulses in the picosecond regime. The amplified chirped pulses show distortion appearing as pedestals after recompression when the amplifier is operated in saturation....

  11. Fundamentals of laser-assisted fabrication of inorganic and organic films

    DEFF Research Database (Denmark)

    Schou, Jørgen

    2008-01-01

    The standard method for producing films by laser-assisted methods, Pulsed Laser Deposition (PLD) will be reviewed. The films considered are usually inorganic films, but also films of organic materials have been produced. Also the deposition of organic films by MAPLE (Matrix Assisted Pulsed Laser...

  12. Optical pulse compression

    International Nuclear Information System (INIS)

    Glass, A.J.

    1975-01-01

    The interest in using large lasers to achieve a very short and intense pulse for generating fusion plasma has provided a strong impetus to reexamine the possibilities of optical pulse compression at high energy. Pulse compression allows one to generate pulses of long duration (minimizing damage problems) and subsequently compress optical pulses to achieve the short pulse duration required for specific applications. The ideal device for carrying out this program has not been developed. Of the two approaches considered, the Gires--Tournois approach is limited by the fact that the bandwidth and compression are intimately related, so that the group delay dispersion times the square of the bandwidth is about unity for all simple Gires--Tournois interferometers. The Treacy grating pair does not suffer from this limitation, but is inefficient because diffraction generally occurs in several orders and is limited by the problem of optical damage to the grating surfaces themselves. Nonlinear and parametric processes were explored. Some pulse compression was achieved by these techniques; however, they are generally difficult to control and are not very efficient. (U.S.)

  13. RF Pulsed Heating

    Energy Technology Data Exchange (ETDEWEB)

    Pritzkau, David P.

    2002-01-03

    RF pulsed heating is a process by which a metal is heated from magnetic fields on its surface due to high-power pulsed RF. When the thermal stresses induced are larger than the elastic limit, microcracks and surface roughening will occur due to cyclic fatigue. Pulsed heating limits the maximum magnetic field on the surface and through it the maximum achievable accelerating gradient in a normal conducting accelerator structure. An experiment using circularly cylindrical cavities operating in the TE{sub 011} mode at a resonant frequency of 11.424 GHz is designed to study pulsed heating on OFE copper, a material commonly used in normal conducting accelerator structures. The high-power pulsed RF is supplied by an X-band klystron capable of outputting 50 MW, 1.5 {micro}s pulses. The test pieces of the cavity are designed to be removable to allow testing of different materials with different surface preparations. A diagnostic tool is developed to measure the temperature rise in the cavity utilizing the dynamic Q change of the resonant mode due to heating. The diagnostic consists of simultaneously exciting a TE{sub 012} mode to steady-state in the cavity at 18 GHz and measuring the change in reflected power as the cavity is heated from high-power pulsed RF. Two experimental runs were completed. One run was executed at a calculated temperature rise of 120 K for 56 x 10{sup 6} pulses. The second run was executed at a calculated temperature rise of 82 K for 86 x 10{sup 6} pulses. Scanning electron microscope pictures show extensive damage occurring in the region of maximum temperature rise on the surface of the test pieces.

  14. Comparison of pulsed corona plasma and pulsed electric fields for the decontamination of water containing Legionella pneumophila as model organism.

    Science.gov (United States)

    Banaschik, Robert; Burchhardt, Gerhard; Zocher, Katja; Hammerschmidt, Sven; Kolb, Juergen F; Weltmann, Klaus-Dieter

    2016-12-01

    Pulsed corona plasma and pulsed electric fields were assessed for their capacity to kill Legionella pneumophila in water. Electrical parameters such as in particular dissipated energy were equal for both treatments. This was accomplished by changing the polarity of the applied high voltage pulses in a coaxial electrode geometry resulting in the generation of corona plasma or an electric field. For corona plasma, generated by high voltage pulses with peak voltages of +80kV, Legionella were completely killed, corresponding to a log-reduction of 5.4 (CFU/ml) after a treatment time of 12.5min. For the application of pulsed electric fields from peak voltages of -80kV a survival of log 2.54 (CFU/ml) was still detectable after this treatment time. Scanning electron microscopy images of L. pneumophila showed rupture of cells after plasma treatment. In contrast, the morphology of bacteria seems to be intact after application of pulsed electric fields. The more efficient killing for the same energy input observed for pulsed corona plasma is likely due to induced chemical processes and the generation of reactive species as indicated by the evolution of hydrogen peroxide. This suggests that the higher efficacy and efficiency of pulsed corona plasma is primarily associated with the combined effect of the applied electric fields and the promoted reaction chemistry. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Dynamic pulse difference circuit

    International Nuclear Information System (INIS)

    Erickson, G.L.

    1978-01-01

    A digital electronic circuit of especial use for subtracting background activity pulses in gamma spectrometry is disclosed which comprises an up-down counter connected to count up with signal-channel pulses and to count down with background-channel pulses. A detector responsive to the count position of the up-down counter provides a signal when the up-down counter has completed one scaling sequence cycle of counts in the up direction. In an alternate embodiment, a detector responsive to the count position of the up-down counter provides a signal upon overflow of the counter

  16. Coaxial pulse matching transformer

    International Nuclear Information System (INIS)

    Ledenev, V.V.; Khimenko, L.T.

    1986-01-01

    This paper describes a coaxial pulse matching transformer with comparatively simple design, increased mechanical strength, and low stray inductance. The transformer design makes it easy to change the turns ratio. The circuit of the device and an expression for the current multiplication factor are presented; experiments confirm the efficiency of the transformer. Apparatus with a coaxial transformer for producing high-power pulsed magnetic fields is designed (current pulses of 1-10 MA into a load and a natural frequency of 100 kHz)

  17. Pulse-width discriminators

    International Nuclear Information System (INIS)

    Budyashov, Yu.G.; Grebenyuk, V.M.; Zinov, V.G.

    1978-01-01

    A pulse duration discriminator is described which is intended for processing signals from multilayer scintillators. The basic elements of the scintillator are: an input gate, a current generator, an integrating capacitor, a Schmidt trigger and an anticoincidence circuit. The basic circuit of the discriminator and its time diagrams explaining its operating are given. The discriminator is based on microcircuits. Pulse duration discrimination threshold changes continuously from 20 to 100 ns, while its amplitude threshold changes within 20 to 100 mV. The temperature instability of discrimination thresholds (both in pulse width and in amplitude) is better than 0.1 per cent/deg C

  18. Multimode pulse counter

    International Nuclear Information System (INIS)

    Natanzon, D.D.

    1982-01-01

    A pulse counter with code conversion is described. The counter is based on the integrated circuits of direct-counting devices of medium integration. The counter ensures various modes of pulse counting depending on the logical control signals: reversible, two-channel summing, one-channel summing binary, summing with ''storage'' signal code fixation without interrupting pulse counting. Arrangement of the suggested structure as a microcircuit of medium integration might contribute to reduction in the counter type nomenclature in digital families of widely used integrated circuits

  19. Pulsed atomic soliton laser

    International Nuclear Information System (INIS)

    Carr, L.D.; Brand, J.

    2004-01-01

    It is shown that simultaneously changing the scattering length of an elongated, harmonically trapped Bose-Einstein condensate from positive to negative and inverting the axial portion of the trap, so that it becomes expulsive, results in a train of self-coherent solitonic pulses. Each pulse is itself a nondispersive attractive Bose-Einstein condensate that rapidly self-cools. The axial trap functions as a waveguide. The solitons can be made robustly stable with the right choice of trap geometry, number of atoms, and interaction strength. Theoretical and numerical evidence suggests that such a pulsed atomic soliton laser can be made in present experiments

  20. DogPulse

    DEFF Research Database (Denmark)

    Skovgaard, Christoffer; Thomsen, Josephine Raun; Verdezoto, Nervo

    2015-01-01

    This paper presents DogPulse, an ambient awareness system to support the coordination of dog walking among family members at home. DogPulse augments a dog collar and leash set to activate an ambient shape-changing lamp and visualize the last time the dog was taken for a walk. The lamp gradually...... changes its form and pulsates its lights in order to keep the family members aware of the dog walking activity. We report the iterative prototyping of DogPulse, its implementation and its preliminary evaluation. Based on our initial findings, we present the limitations and lessons learned as well...

  1. Study of startup conditions of a pulsed annular reactor

    International Nuclear Information System (INIS)

    Silva, Mario Augusto Bezerra da

    2003-10-01

    A new concept of reactor, which combines features of pulsed and stationary reactors, was proposed so as to produce intense neutronic fluxes. Such a reactor, known as VICHFPR (Very Intense Continuous High Flux Pulsed Reactor), consists of a subcritical core with an annular geometry and pulsed by a rotating reflector which acts as a reactivity modulator as it produces a short pulse (approximately equal to 1 ms) of high intensity, guiding the region near the pulser to super-prompt critical state. This dissertation intends to analyze the startup conditions of a Pulsed Annular Reactor. The evolution of the neutron pulse intensity is analyzed when the reactivity modulator is brought upwards according to a helicoidal path from its initial position (far away from the core), when the multiplication factor has a subcritical value, up to the final position (near the core), in which a super-prompt critical state is reached. Part of the analysis is based on the variation of neutron reflection, which is a uniform function of the exit and reflection angles between the core and the modulator. It must be emphasized that this work is an approximation of the real situation. As the initial and final reactor parameters are known, a programming code in Fortran is worked out to provide the multiplication factor and the flux intensity evolution. According to the results obtained with this code, the conditions under which the modulator must be lifted up during the startup are established. Basically, these conditions are related to the analysis of the rising and the rotation velocities, the reflector saving and the initial distance between the reactor and the modulator. The Pulsed Annular Reactor startup was divided into three stages. Because of its negative reactivity in the first two stages, the neutron multiplication is not large, while the last one, having a positive reactivity, shows an intense multiplication as is usually expected when handling pulsed systems. This last stage is quite

  2. Assisted Living

    Science.gov (United States)

    ... a resident's needs depends as much on the philosophy and services of the assisted living facility as it does on the quality of care. The Administration on Aging, a part of the U.S. Department of Health and Human Services (HHS), offers these suggestions to help you ...

  3. Assistive Devices

    Science.gov (United States)

    If you have a disability or injury, you may use a number of assistive devices. These are tools, products or types of equipment that help you perform tasks and activities. They may help you move around, see, communicate, eat, or get ...

  4. Spring 5 & reactive streams

    CERN Multimedia

    CERN. Geneva; Clozel, Brian

    2017-01-01

    Spring is a framework widely used by the world-wide Java community, and it is also extensively used at CERN. The accelerator control system is constituted of 10 million lines of Java code, spread across more than 1000 projects (jars) developed by 160 software engineers. Around half of this (all server-side Java code) is based on the Spring framework. Warning: the speakers will assume that people attending the seminar are familiar with Java and Spring’s basic concepts. Spring 5.0 and Spring Boot 2.0 updates (45 min) This talk will cover the big ticket items in the 5.0 release of Spring (including Kotlin support, @Nullable and JDK9) and provide an update on Spring Boot 2.0, which is scheduled for the end of the year. Reactive Spring (1h) Spring Framework 5.0 has been released - and it now supports reactive applications in the Spring ecosystem. During this presentation, we'll talk about the reactive foundations of Spring Framework with the Reactor project and the reactive streams specification. We'll al...

  5. Reactivity of nitriles

    International Nuclear Information System (INIS)

    Kukushkin, Yu.N.

    1987-01-01

    Reactivity of coordination nitriles in transition metal (Ru, Mo, W, Zr, Hf) complexes, namely: transformation of nitriles of the first coordination sphere into N-acyl-substituted amides, amidines, nitrile interaction; with water, alkalines, alcoholes, hydrogen, azide and cyanide ions is considered. Introduction of acetonitrile molecule to uranium (4)-carbon double bond is discussed

  6. Clojure reactive programming

    CERN Document Server

    Borges, Leonardo

    2015-01-01

    If you are a Clojure developer who is interested in using Reactive Programming to build asynchronous and concurrent applications, this book is for you. Knowledge of Clojure and Leiningen is required. Basic understanding of ClojureScript will be helpful for the web chapters, although it is not strictly necessary.

  7. A Universal Reactive Machine

    DEFF Research Database (Denmark)

    Andersen, Henrik Reif; Mørk, Simon; Sørensen, Morten U.

    1997-01-01

    Turing showed the existence of a model universal for the set of Turing machines in the sense that given an encoding of any Turing machine asinput the universal Turing machine simulates it. We introduce the concept of universality for reactive systems and construct a CCS processuniversal...

  8. Chemical Reactivity Test (CRT)

    Energy Technology Data Exchange (ETDEWEB)

    Zaka, F. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-12-13

    The Chemical Reactivity Test (CRT) is used to determine the thermal stability of High Explosives (HEs) and chemical compatibility between (HEs) and alien materials. The CRT is one of the small-scale safety tests performed on HE at the High Explosives Applications Facility (HEAF).

  9. Reactive power compensating system

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Timothy J. (Redondo Beach, CA); El-Sharkawi, Mohamed A. (Renton, WA); Venkata, Subrahmanyam S. (Seattle, WA)

    1987-01-01

    The reactive power of an induction machine is compensated by providing fixed capacitors on each phase line for the minimum compensation required, sensing the current on one line at the time its voltage crosses zero to determine the actual compensation required for each phase, and selecting switched capacitors on each line to provide the balance of the compensation required.

  10. Reactive Power Compensating System.

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Timothy J.; El-Sharkawi, Mohamed A.; Venkata, Subrahmanyam S.

    1985-01-04

    The circuit was designed for the specific application of wind-driven induction generators. It has great potential for application in any situation where a varying reactive power load is present, such as with induction motors or generators, or for transmission network compensation.

  11. The iodine reactivity

    International Nuclear Information System (INIS)

    2003-01-01

    The iodine is an important element because it has long life isotopes (such as iodine 129) and a great mobility in natural media. Iodine presents a complex chemistry because of its volatility and its strong redox reactivity. The S.E.C.R. works to better understand the reactivity of this element in different natural, industrial or biological environments. It plays a part in thermochemical sites as a possible way of hydrogen formation. This seminar gives some aspects relative to the chemical reactivity of iodine, since its thermochemistry in the I/S cycles to produce hydrogen to its reactivity in the natural medium and its potential radiological impact. This document includes 4 presentations transparencies) dealing with: the 129 I cycle rejected in the low radioactive gaseous and liquid effluents of the La Hague reprocessing plant (C. Frechou); a bibliographic review of iodine retention in soils (F. Bazer-Bachi); the hydrogen production and the iodine/sulfur thermochemical cycle (role of iodine in the process); and the direct characterization by electro-spray ionization mass spectroscopy of iodine fixation by fulvic acids (P. Reiller, B. Amekraz, C. Moulin, V. Moulin)

  12. Upscaling of reactive flows

    NARCIS (Netherlands)

    Kumar, K.

    2012-01-01

    The thesis deals with the upscaling of reactive flows in complex geometry. The reactions which may include deposition or dissolution take place at a part of the boundary and depending on the size of the reaction domain, the changes in the pore structure that are due to the deposition process may or

  13. Plasma ``anti-assistance'' and ``self-assistance'' to high power impulse magnetron sputtering

    Science.gov (United States)

    Anders, André; Yushkov, Georgy Yu.

    2009-04-01

    A plasma assistance system was investigated with the goal to operate high power impulse magnetron sputtering (HiPIMS) at lower pressure than usual, thereby to enhance the utilization of the ballistic atoms and ions with high kinetic energy in the film growth process. Gas plasma flow from a constricted plasma source was aimed at the magnetron target. Contrary to initial expectations, such plasma assistance turned out to be contraproductive because it led to the extinction of the magnetron discharge. The effect can be explained by gas rarefaction. A better method of reducing the necessary gas pressure is operation at relatively high pulse repetition rates where the afterglow plasma of one pulse assists in the development of the next pulse. Here we show that this method, known from medium-frequency (MF) pulsed sputtering, is also very important at the much lower pulse repetition rates of HiPIMS. A minimum in the possible operational pressure is found in the frequency region between HiPIMS and MF pulsed sputtering.

  14. Plasma 'anti-assistance' and 'self-assistance' to high power impulse magnetron sputtering

    International Nuclear Information System (INIS)

    Anders, Andre; Yushkov, Georgy Yu.

    2009-01-01

    A plasma assistance system was investigated with the goal to operate high power impulse magnetron sputtering (HiPIMS) at lower pressure than usual, thereby to enhance the utilization of the ballistic atoms and ions with high kinetic energy in the film growth process. Gas plasma flow from a constricted plasma source was aimed at the magnetron target. Contrary to initial expectations, such plasma assistance turned out to be contraproductive because it led to the extinction of the magnetron discharge. The effect can be explained by gas rarefaction. A better method of reducing the necessary gas pressure is operation at relatively high pulse repetition rates where the afterglow plasma of one pulse assists in the development of the next pulse. Here we show that this method, known from medium-frequency (MF) pulsed sputtering, is also very important at the much lower pulse repetition rates of HiPIMS. A minimum in the possible operational pressure is found in the frequency region between HiPIMS and MF pulsed sputtering

  15. Rapid thermal pulse annealing

    International Nuclear Information System (INIS)

    Miller, M.G.; Koehn, B.W.; Chaplin, R.L.

    1976-01-01

    Characteristics of recovery processes have been investigated for cases of heating a sample to successively higher temperatures by means of isochronal annealing or by using a rapid pulse annealing. A recovery spectra shows the same features independent of which annealing procedure is used. In order to determine which technique provides the best resolution, a study was made of how two independent first-order processes are separated for different heating rates and time increments of the annealing pulses. It is shown that the pulse anneal method offers definite advantages over isochronal annealing when annealing for short time increments. Experimental data by means of the pulse anneal techniques are given for the various substages of stage I of aluminium. (author)

  16. Pulse holographic measurement techniques

    International Nuclear Information System (INIS)

    Kim, Cheol Jung; Baik, Seong Hoon; Hong, Seok Kyung; Kim, Jeong Moog; Kim, Duk Hyun

    1992-01-01

    With the development of laser, remote inspection techniques using laser have been growing on. The inspection and measurement techniques by pulse holography are well-established technique for precise measurement, and widely used in various fields of industry now. In nuclear industry, this technology is practically used because holographic inspection is remote, noncontact, and precise measurement technique. In relation to remote inspection technology in nuclear industry, state-of-the art of pulse HNDT (Holographic non-destructive testing) and holographic measurement techniques are examined. First of all, the fundamental principles as well as practical problems for applications are briefly described. The fields of pulse holography have been divided into the HNDT, flow visualization and distribution study, and other application techniques. Additionally holographic particle study, bubble chamber holography, and applications to other visualization techniques are described. Lastly, the current status for the researches and applications of pulse holography to nuclear industry which are carried out actively in Europe and USA, is described. (Author)

  17. IAE pulsed electrostatic accelerator

    International Nuclear Information System (INIS)

    Afanas'ev, V.P.; Ganzhelyuk, M.L.; Kozlov, L.D.; Koltypin, E.A.; Molchanov, Yu.D.; Otroshchenko, G.A.; Yan'kov, G.B.

    1976-01-01

    The modernized pulse electrostatic accelerator using the klystron ion grouping and the beam interruption system prior to acceleration is described. The accelerator is modernized in order to improve parameters of a current pulse and to decrease the background in the measurement room. The ion beam of needed dimensions is obtained with the help of a high-frequency source and a beam grouping and deflection system. The general view of the beam grouping and deflection system is shown. The ion beam forming process is considered in detail. The modernized electrostatic accelerator permits to obtain a pulse current with a pulse length of 1.5 ns and an amplitude of 1.5 - 2 μA. With the repetition frequency of 2 MHz, the average target current is about 6 μA

  18. International Year of Pulses 2016 | 2016 International Year of Pulses

    Science.gov (United States)

    the Year in collaboration with Governments, relevant organizations, non-governmental organizations and the composition of pulses Image 4 Wrapping up the International Year of Pulses The 5 key messages to food security Infographic Pulses and climate change International Year of Pulses 2016 The 68th UN

  19. Realtime aspects of pulse-to-pulse modulation

    International Nuclear Information System (INIS)

    Steiner, R.; Riedel, C.; Roesch, W.

    1992-01-01

    The pulse-to-pulse modulation of the SIS-ESR control system is described. Fast response to operator interaction and to changes in process conditions is emphasized as well as the essential part played by the timing system in pulse-to-pulse modulation. (author)

  20. Pulsed spallation Neutron Sources

    International Nuclear Information System (INIS)

    Carpenter, J.M.

    1994-01-01

    This paper reviews the early history of pulsed spallation neutron source development at Argonne and provides an overview of existing sources world wide. A number of proposals for machines more powerful than currently exist are under development, which are briefly described. The author reviews the status of the Intense Pulsed Neutron Source, its instrumentation, and its user program, and provides a few examples of applications in fundamental condensed matter physics, materials science and technology

  1. Pulsed spallation neutron sources

    International Nuclear Information System (INIS)

    Carpenter, J.M.

    1996-01-01

    This paper reviews the early history of pulsed spallation neutron source development ar Argonne and provides an overview of existing sources world wide. A number of proposals for machines more powerful than currently exist are under development, which are briefly described. The author reviews the status of the Intense Pulsed Neutron Source, its instrumentation, and its user program, and provide a few examples of applications in fundamental condensed matter physics, materials science and technology

  2. Foreign assistance

    International Nuclear Information System (INIS)

    1991-07-01

    This paper reports that providing energy assistance to developing countries remains a relatively low priority of the Agency for International Development. AID is helping some developing countries meet their energy needs, but this assistance varies substantially because of the agency's decentralized structure. Most AID energy funding has gone to a handful of countries-primarily Egypt and Pakistan. With limited funding in most other countries, AID concentrates on providing technical expertise and promoting energy policy reforms that will encourage both energy efficiency and leverage investment by the private sector and other donors. Although a 1989 congressional directive to pursue a global warming initiative has had a marginal impact on the agency's energy programming, many AID energy programs, including those directed at energy conservation, help address global warming concerns

  3. Immune reactivities against gums.

    Science.gov (United States)

    Vojdani, Aristo; Vojdani, Charlene

    2015-01-01

    Different kinds of gums from various sources enjoy an extremely broad range of commercial and industrial use, from food and pharmaceuticals to printing and adhesives. Although generally recognized as safe by the US Food and Drug Administration (FDA), gums have a history of association with sensitive or allergic reactions. In addition, studies have shown that gums have a structural, molecular similarity to a number of common foods. A possibility exists for cross-reactivity. Due to the widespread use of gums in almost every aspect of modern life, the overall goal of the current investigation was to determine the degree of immune reactivity to various gum antigens in the sera of individuals representing the general population. The study was a randomized, controlled trial. 288 sera purchased from a commercial source. The sera was screened for immunoglobulin G (IgG) and immunoglobulin E (IgE) antibodies against extracts of mastic gum, carrageenan, xantham gum, guar gum, gum tragacanth, locust bean gum, and β-glucan, using indirect enzyme-linked immunosorbent assay (ELISA) testing. For each gum antigen, inhibition testing was performed on the 4 sera that showed the highest IgG and IgE immune reactivity against the different gums used in the study. Inhibition testing on these same sera for sesame albumin, lentil, corn, rice, pineapple, peanut, pea protein, shrimp, or kidney bean was used to determine the cross-reactivity of these foods with the gum. Of the 288 samples, 4.2%-27% of the specimens showed a significant elevation in IgG antibodies against various gums. Only 4 of 288, or 1.4%, showed a simultaneous elevation of the IgG antibody against all 7 gum extracts. For the IgE antibody, 15.6%-29.1% of the specimens showed an elevation against the various gums. A significant percentage of the specimens, 12.8%, simultaneously produced IgE antibodies against all 7 tested extracts. Overall, the percentage of elevation in IgE antibodies against different gum extracts, with

  4. Particle acceleration by electromagnetic pulses

    International Nuclear Information System (INIS)

    Lai, H.M.

    1982-01-01

    Particle interaction with plane electromagnetic pulses is studied. It is shown that particle acceleration by a wavy pulse, depending on the shape of the pulse, may not be small. Further, a diffusive-type particle acceleration by multiple weak pulses is described and discussed. (author)

  5. Pulsed-laser atom-probe field-ion microscopy

    International Nuclear Information System (INIS)

    Kellogg, G.L.; Tsong, T.T.

    1980-01-01

    A time-of-flight atom-probe field-ion microscope has been developed which uses nanosecond laser pulses to field evaporate surface species. The ability to operate an atom-probe without using high-voltage pulses is advantageous for several reasons. The spread in energy arising from the desorption of surface species prior to the voltage pulse attaining its maximum amplitude is eliminated, resulting in increased mass resolution. Semiconductor and insulator samples, for which the electrical resistivity is too high to transmit a short-duration voltage pulse, can be examined using pulsed-laser assisted field desorption. Since the electric field at the surface can be significantly smaller, the dissociation of molecular adsorbates by the field can be reduced or eliminated, permitting well-defined studies of surface chemical reactions. In addition to atom-probe operation, pulsed-laser heating of field emitters can be used to study surface diffusion of adatoms and vacancies over a wide range of temperatures. Examples demonstrating each of these advantages are presented, including the first pulsed-laser atom-probe (PLAP) mass spectra for both metals (W, Mo, Rh) and semiconductors (Si). Molecular hydrogen, which desorbs exclusively as atomic hydrogen in the conventional atom probe, is shown to desorb undissociatively in the PLAP. Field-ion microscope observations of the diffusion and dissociation of atomic clusters, the migration of adatoms, and the formation of vacancies resulting from heating with a 7-ns laser pulse are also presented

  6. What makes ecological systems reactive?

    Science.gov (United States)

    Snyder, Robin E

    2010-06-01

    Although perturbations from a stable equilibrium must ultimately vanish, they can grow initially, and the maximum initial growth rate is called reactivity. Reactivity thus identifies systems that may undergo transient population surges or drops in response to perturbations; however, we lack biological and mathematical intuition about what makes a system reactive. This paper presents upper and lower bounds on reactivity for an arbitrary linearized model, explores their strictness, and discusses their biological implications. I find that less stable systems (i.e. systems with long transients) have a smaller possible range of reactivities for which no perturbations grow. Systems with more species have a higher capacity to be reactive, assuming species interactions do not weaken too rapidly as the number of species increases. Finally, I find that in discrete time, reactivity is determined largely by mean interaction strength and neither discrete nor continuous time reactivity are sensitive to food web topology. 2010 Elsevier Inc. All rights reserved.

  7. Dynamics of traveling reaction pulses

    International Nuclear Information System (INIS)

    Dovzhenko, A. Yu.; Rumanov, E. N.

    2007-01-01

    The growth of activator losses is accompanied by the decay of a traveling reaction pulse. In a ring reactor, this propagation threshold is present simultaneously with a threshold related to the ring diameter. The results of numerical experiments with pulses of an exothermal reaction reveal the transition from pulse propagation to a homogeneous hot regime, established regimes with periodic variations of the pulse velocity, and oscillatory decay of the pulse. When the medium becomes 'bistable' as a result of the variation in parameters, this factor does not prevent the propagation of pulses, but leads to changes in the pulse structure

  8. Bearing for the reactivation

    International Nuclear Information System (INIS)

    Santamaria Alexandra

    2003-01-01

    Ecopetrol undertook an aggressive plan to reactivate the activities of seismic that allows fulfilling the goals proposed for this year (2003). Although the production registered a descent of 9%, the financial results throw utilities for $1.1 trillion pesos to the closing of September and contributions in bonuses for $1.2 trillions. The author also refers to the general balance, to the finances, raw production, taxes and transfers

  9. Processing and analyses of the pulsed-neutron experimental data of the YALINA facility

    International Nuclear Information System (INIS)

    Cao, Y.; Gohar, Y.; Smith, D.; Talamo, A.; Zhong, Z.; Kiyavitskaya, H.; Bournos, V.; Fokov, Y.; Routkovskaya, C.; Sadovich, S.

    2010-01-01

    Full text: The YALINA subcritical assembly of the Joint Institute for Power and Nuclear Research (JIPNR)-Sosny, Belarus has been utilized to study the physics parameters of accelerator driven systems (ADS) with high intensity Deuterium-Tritium and Deuterium-Deuterium pulsed neutron sources. In particular, with the fast and thermal neutron zones of the YALINA-Booster subcritical assembly, the pulsed neutron experiments have been utilized to evaluate the pulsed neutron methods for determining the reactivity of the subcritical system. In this paper, the pulsed-neutron experiments performed in the YALINA-Booster 1141 configuration with 90% U 235 fuel and 1185 configuration with 36% and 21% U fuel are examined and analized. The Sjo:strand area-ratio method is utilized to determine the reactivities of the subcritical assembly configurations. The linear regression method is applied to obtain the prompt neutron decay constants from the pulsed-neutron experimental data. The reactivity values obtained from experimental data are shown to be dependent on the detector locations and also on the detector types. The large discrepancies between the reactivity values given by the detectors in the fast neutron zone was reduced by spatial correction methods, and the estimated reactivity after the spatial corrections are almost spatially independent.

  10. TEMPLATE-ASSISTED FABRICATION AND DIELECTROPHORETIC MANIPULATION OF PZT MICROTUBES

    Directory of Open Access Journals (Sweden)

    VLADIMÍR KOVAĽ

    2012-09-01

    Full Text Available Mesoscopic high aspect ratio ferroelectric tube structures of a diverse range of compositions with tailored physical properties can be used as key components in miniaturized flexible electronics, nano- and micro-electro-mechanical systems, nonvolatile FeRAM memories, and tunable photonic applications. They are usually produced through advanced “bottom-up” or “topdown” fabrication techniques. In this study, a template wetting approach is employed for fabrication of Pb(Zr0.52Ti0.48O3 (PZT microtubes. The method is based on repeated infiltration of precursor solution into macroporous silicon (Si templates at a sub-atmospheric pressure. Prior to crystallization at 750°C, free-standing tubes of a 2-μm outer diameter, extending to over 30 μm in length were released from the Si template using a selective isotropic-pulsed XeF2 reactive ion etching. To facilitate rapid electrical characterization and enable future integration process, directed positioning and aligning of the PZT tubes was performed by dielectrophoresis. The electric field-assisted technique involves an alternating electric voltage that is applied through pre-patterned microelectrodes to a colloidal suspension of PZT tubes dispersed in isopropyl alcohol. The most efficient biasing for the assembly of tubes across the electrode gap of 12 μm was a square wave signal of 5 Vrms and 10 Hz. By varying the applied frequency in between 1 and 10 Hz, an enhancement in tube alignment was obtained.

  11. Pulsed rf excited spectrometer having improved pulse width control

    International Nuclear Information System (INIS)

    1977-01-01

    RF excitation for a spectrometer is obtained by pulse width modulating an RF carrier to produce the desired broadband RF exciting spectrum. The RF excitation includes a train of composite RF pulses, each composite pulse having a primary pulse portion of a first RF phase and a second pulse portion of a second RF phase opposite that of the first. In this manner, the finite rise and fall times of the primary pulse portion are compensated for by the corresponding rise and fall times of the secondary pulse portion. The primary pulse portion is lengthened by an amount equal to the secondary pulse portion so that the secondary pulse portion cancels the added primary pulse portion. In a spectrometer, the compensating second pulse component removes certain undesired side bands of the RF excitation caused by the finite rise and fall times of the applied RF pulses. The compensating second pulse component removes certain undesired side bands associated with each of the resonant lines of the excited resonance spectrum of the sample under analysis, particularly for wide band RF excitation

  12. Multilayered metal oxide thin film gas sensors obtained by conventional and RF plasma-assisted laser ablation

    International Nuclear Information System (INIS)

    Mitu, B.; Marotta, V.; Orlando, S.

    2006-01-01

    Multilayered thin films of In 2 O 3 and SnO 2 have been deposited by conventional and RF plasma-assisted reactive pulsed laser ablation, with the aim to evaluate their behaviour as toxic gas sensors. The depositions have been carried out by a frequency doubled Nd-YAG laser (λ = 532 nm, τ = 7 ns) on Si(1 0 0) substrates, in O 2 atmosphere. The thin films have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrical resistance measurements. A comparison of the electrical response of the simple (indium oxide, tin oxide) and multilayered oxides to toxic gas (nitric oxide, NO) has been performed. The influence on the structural and electrical properties of the deposition parameters, such as substrate temperature and RF power is reported

  13. Herophilus on pulse

    Directory of Open Access Journals (Sweden)

    Afonasin, Eugene

    2015-01-01

    Full Text Available The first detailed study of the pulse (sphygmology is associated in antiquity with Herophilus (the end of the 4th century BCE, an Alexandrian physician, renowned for his anatomical discoveries. The scholars also attribute to him a discovery of a portable and adjustable water-clock, used for measuring ‘natural’ and ‘unnatural’ pulse and, accordingly, temperature of the patient. In the article we translate the principal ancient evidences and comment upon them. We study both the practical aspects of ancient sphygmology and the theoretical speculations associated with it. Ancient theory of proportion and musical harmony allowed to build a classification of the pulses, but the medical experience did not fit well in the Procrustean bed of this rather simple theory.

  14. Current Extensions on PULSE

    Directory of Open Access Journals (Sweden)

    Sanda Dragos

    2010-09-01

    Full Text Available Using a learning management system (LMS is a common practise nowadays. Such instruments are used in educational institutions to enhance and support the teaching act as well as in industry for training purposes. In a computer science department of an university such instrument tends to be a basic requirement. That is because not only it allows a better management of courses and a better communication between students and professors, but can also serve as a perfect instrument for presenting teaching related materials for computer science subjects. During the years I have created and used several such instruments: a System with Interactive ackNowledgement and Evaluation of students work during laboratory sessions (SINE, a Php Utility used in Laboratories for Student Evaluation (PULSE, and PULSE Extended. The aim of this paper is to present the current enhancements of PULSE.

  15. Programming Reactive Extensions and LINQ

    CERN Document Server

    Liberty, Jesse

    2011-01-01

    Pro Reactive Extensions and LINQ is a deep dive into the next important technology for .NET developers: Reactive Extensions. This in-depth tutorial goes beyond what is available anywhere else to teach how to write WPF, Silverlight, and Windows Phone applications using the Reactive Extensions (Rx) to handle events and asynchronous method calls. Reactive programming allows you to turn those aspects of your code that are currently imperative into something much more event-driven and flexible. For this reason, it's sometimes referred to as LINQ for Events. Reactive programming hinges on the concep

  16. Theory of laser-assisted autoionization by attosecond light pulses

    International Nuclear Information System (INIS)

    Zhao, Z.X.; Lin, C.D.

    2005-01-01

    We present a quantum theory of the decay of an autoionizing state created in the attosecond xuv (extreme ultraviolet) pump and laser probe measurements within the strong field approximation employing resonance parameters from Fano's theory. From the electron spectra versus the pump-probe time delay, we show how the lifetimes of the resonances can be extracted directly from the time domain measurements

  17. Millimicrosecond pulse techniques

    CERN Document Server

    Lewis, Ian A D

    1959-01-01

    Millimicrosecond Pulse Techniques, Second Edition focuses on millimicrosecond pulse techniques and the development of devices of large bandwidth, extending down to comparatively low frequencies (1 Mc/s). Emphasis is on basic circuit elements and pieces of equipment of universal application. Specific applications, mostly in the field of nuclear physics instrumentation, are considered. This book consists of eight chapters and opens with an introduction to some of the terminology employed by circuit engineers as well as theoretical concepts, including the laws of circuit analysis, Fourier analysi

  18. Pulsed Plasma Electron Sources

    Science.gov (United States)

    Krasik, Yakov

    2008-11-01

    Pulsed (˜10-7 s) electron beams with high current density (>10^2 A/cm^2) are generated in diodes with electric field of E > 10^6 V/cm. The source of electrons in these diodes is explosive emission plasma, which limits pulse duration; in the case E Saveliev, J. Appl. Phys. 98, 093308 (2005). Ya. E. Krasik, A. Dunaevsky, and J. Felsteiner, Phys. Plasmas 8, 2466 (2001). D. Yarmolich, V. Vekselman, V. Tz. Gurovich, and Ya. E. Krasik, Phys. Rev. Lett. 100, 075004 (2008). J. Z. Gleizer, Y. Hadas and Ya. E. Krasik, Europhysics Lett. 82, 55001 (2008).

  19. Spallation neutrons pulsed sources

    International Nuclear Information System (INIS)

    Carpenter, J.

    1996-01-01

    This article describes the range of scientific applications which can use these pulsed neutrons sources: Studies on super fluids, measures to verify the crawling model for the polymers diffusion; these sources are also useful to study the neutron disintegration, the ultra cold neutrons. In certain applications which were not accessible by neutrons diffusion, for example, radiations damages, radionuclides production and activation analysis, the spallation sources find their use and their improvement will bring new possibilities. Among others contributions, one must notice the place at disposal of pulsed muons sources and neutrinos sources. (N.C.). 3 figs

  20. Pulse Doppler radar

    CERN Document Server

    Alabaster, Clive

    2012-01-01

    This book is a practitioner's guide to all aspects of pulse Doppler radar. It concentrates on airborne military radar systems since they are the most used, most complex, and most interesting of the pulse Doppler radars; however, ground-based and non-military systems are also included. It covers the fundamental science, signal processing, hardware issues, systems design and case studies of typical systems. It will be a useful resource for engineers of all types (hardware, software and systems), academics, post-graduate students, scientists in radar and radar electronic warfare sectors and milit

  1. Pulse Synchronization System (PSS)

    International Nuclear Information System (INIS)

    1977-06-01

    This document is intended to serve as an operations manual, as well as a documentation of the backup analyses pertinent to the design as delivered. A history of earlier unsuccessful versions of the Pulse Synchronization System (PSS) is not included. The function of the PSS is to synchronize the time of arrival at the fusion target of laser pulses that are propagated through the 20 amplifier chains of the SHIVA laser. The positional accuracy requirement is +-1.5 mm (+-5 psec), and is obtained by the PSS with a wide margin factor

  2. Reactivity costs in MARIA reactor

    International Nuclear Information System (INIS)

    Marcinkowska, Zuzanna E.; Pytel, Krzysztof M.; Frydrysiak, Andrzej

    2017-01-01

    Highlights: • The methodology for calculating consumed fuel cost of excess reactivity is proposed. • Correlation between time integral of the core excess reactivity and released energy. • Reactivity price gives number of fuel elements required for given excess reactivity. - Abstract: For the reactor operation at high power level and carrying out experiments and irradiations the major cost of reactor operation is the expense of nuclear fuel. In this paper the methodology for calculating consumed fuel cost-relatedness of excess reactivity is proposed. Reactivity costs have been determined on the basis of operating data. A number of examples of calculating the reactivity costs for processes such as: strong absorbing material irradiation, molybdenium-99 production, beryllium matrix poisoning and increased moderator temperature illustrates proposed method.

  3. Studies on pulsed hollow cathode capillary discharges

    Energy Technology Data Exchange (ETDEWEB)

    Choi, P; Dumitrescu-Zoita, C; Larour, J; Rous, J [Ecole Polytechnique, 91 - Palaiseau (France). Lab. de Physique des Milieux Ionises; Favre, M; Moreno, J; Chuaqui, H; Wyndham, E [Pontificia Univ. Catolica de Chile, Santiago (Chile). Facultad de Fisica; Zambra, M [Comision Chilena de Energia Nuclear, Santiago (Chile); Wong, C S [Univ. of Malaya, Kuala Lumpur (Malaysia). Plasma Research Lab

    1997-12-31

    Preliminary results on radiation characteristics of pulsed hollow cathode capillary discharges are presented. The device combines the on axis electron beam assisted ionization capabilities of the transient hollow cathode discharge with a novel high voltage low inductance geometrical design, which integrates the local energy storage into the electrode system. A nanosecond regime high temperature plasma is produced in a long, high aspect ratio capillary, with light emission in the UV to XUV region. The discharge is operated from near vacuum to pressure in the 1000 mTorr range. (author). 2 figs., 7 refs.

  4. Reactivity insertion accident analysis

    International Nuclear Information System (INIS)

    Moreira, J.M.L.; Nakata, H.; Yorihaz, H.

    1990-04-01

    The correct prediction of postulated accidents is the fundamental requirement for the reactor licensing procedures. Accident sequences and severity of their consequences depend upon the analysis which rely on analytical tools which must be validated against known experimental results. Present work presents a systematic approach to analyse and estimate the reactivity insertion accident sequences. The methodology is based on the CINETHICA code which solves the point-kinetics/thermohydraulic coupled equations with weighted temperature feedback. Comparison against SPERT experimental results shows good agreement for the step insertion accidents. (author) [pt

  5. Development of novel control system to grow ZnO thin films by reactive evaporation

    Directory of Open Access Journals (Sweden)

    Gerardo Gordillo

    2016-07-01

    Full Text Available This work describes a novel system implemented to grow ZnO thin films by plasma assisted reactive evaporation with adequate properties to be used in the fabrication of photovoltaic devices with different architectures. The innovative aspect includes both an improved design of the reactor used to activate the chemical reaction that leads to the formation of the ZnO compound as an electronic system developed using the virtual instrumentation concept. ZnO thin films with excellent opto-electrical properties were prepared in a reproducible way, controlling the deposition system through a virtual instrument (VI with facilities to control the amount of evaporated zinc involved in the process that gives rise to the formation of ZnO, by means of the incorporation of PID (proportional integral differential and PWM (pulse width modulation control algorithms. The effectiveness and reliability of the developed system was verified by obtaining with good reproducibility thin films of n+-ZnO and i-ZnO grown sequentially in situ with thicknesses and resistivities suitable for use as window layers in chalcopyrite based thin film solar cells.

  6. Pulse power modulators - an overview

    International Nuclear Information System (INIS)

    Venkatramani, N.

    2006-01-01

    Pulse power modulators are electronic devices to provide, high voltage, high current, power bursts. Ideally, a modulator, with the means to shape and control the pulses, acts as a switch between a high voltage power supply and its load. This article gives an overview of the pulse power modulators: starting with the basics of pulse and modulation, it covers modulation topologies, different types of modulators, major subsystems and pulse measurement techniques. The various applications of pulse power modulators and the recent trends have been included at the end. (author)

  7. Obtainment of the subcritical reactivity by mean of measurement of APSD and CPSD employing pulse mode detectors in the IPEN/MB-01 reactor; Obtencao de reatividade subcritica por meio de medidas de APSD e CPSD utilizando detectores modo pulso no Reator IPEN/MB-01

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seung Min

    2014-07-01

    This work presents a new experimental approach to determine the reactivity levels of subcritical systems. The method employs the subcritical kinetic model developed by Gandini and Salvatores and it is based only on measured quantities such as counting rates of the detectors employed in the experiments and the parameters arising from the least squares fitting of the APSD (Auto Power Spectral Density) and CPSD (Cross Power Spectral Density). Detector efficiencies, quantity required in other procedures such as Neutron Source Multiplication (NSM) method, are not needed in the proposed method. The only hypothesis made in the method was the independence of the effective delayed neutron fraction and the prompt neutron generation time to the subcriticality level of the system. The proposed method was applied to measure the reactivity of several subcritical configurations of the IPEN/MB-01 reactor. Measurements of APSD and CPSD were performed in several degrees of subcriticality (up to around -7000 pcm). The spectral densities data were least squares fitted to get the prompt decay mode (α) and other quantities. Beside the startup source of the facility, an external neutron source of Am-Be was installed near the core in order to improve neutron counting statistics. The final experimental results are of good quality. The proposed experimental method shows clearly that the classical point kinetic theory cannot describe the measured reactivity. Instead, the reactivity inferred from this model follows closely the subcriticality index (ζ) for the source arrangements in the experiment. The agreement of the MCNP5 and GPT-TORT results, both with ENDF/B-VII.0 as the basic nuclear data library, when compared to the corresponding experimental ones was also good. (author)

  8. Proton Pulse Radiolysis

    Energy Technology Data Exchange (ETDEWEB)

    Christensen, H C; Nilsson, G; Reitberger, T; Thuomas, K A

    1973-03-15

    A 5 MeV proton accelerator (Van de Graaff) has been used for pulse radiolysis of a number of organic gases and the transient spectra obtained from the alkanes methane, ethane, propane, n-butane and neopentane have tentatively been assigned to alkyl radicals. Some methodological aspects of this new technique are discussed

  9. Lectures on pulsed NMR

    International Nuclear Information System (INIS)

    Pines, A.

    1988-08-01

    These lectures discuss some recent developments in pulsed NMR, emphasizing fundamental principles with selected illustrative applications. Major topics covered include multiple-quantum spectroscopy, spin decoupling, the interaction of spins with a quantized field, adiabatic rapid passage, spin temperature and statistics of cross-polarization, coherent averaging, and zero field NMR. 32 refs., 56 figs

  10. Lectures on pulsed NMR

    International Nuclear Information System (INIS)

    Pines, A.

    1986-09-01

    These lectures discuss some recent developments in pulsed NMR, emphasizing fundamental principles with selected illustrative applications. Major topics covered include multiple-quantum spectroscopy, spin decoupling, the interaction of spins with a quantized field, adiabatic rapid passage, spin temperature and statistics of cross-polarization, coherent averaging, and zero field NMR. 55 figs

  11. Pulsed inductive HF laser

    Energy Technology Data Exchange (ETDEWEB)

    Razhev, A M; Kargapol' tsev, E S [Institute of Laser Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation); Churkin, D S; Demchuk, S V [Novosibirsk State University, Novosibirsk (Russian Federation)

    2016-03-31

    We report the results of experimentally investigated dependences of temporal, spectral and spatial characteristics of an inductive HF-laser generation on the pump conditions. Gas mixtures H{sub 2} – F{sub 2}(NF{sub 3} or SF6{sub 6}) and He(Ne) – H{sub 2} – F{sub 2}(NF{sub 3} or SF{sub 6}) were used as active media. The FWHM pulse duration reached 0.42 μs. This value corresponded to a pulsed power of 45 kW. For the first time, the emission spectrum of an inductive HF laser was investigated, which consisted of seven groups of bands with centres around the wavelengths of 2732, 2736, 2739, 2835, 2837, 2893 and 2913 nm. The cross section profile of the laser beam was a ring with a diameter of about 20 mm and width of about 5 mm. Parameters of laser operation in the repetitively pulsed regime were sufficiently stable. The amplitude instability of light pulses was no greater than 5% – 6%. (lasers)

  12. Optimum transformer design for a pulsed power system

    International Nuclear Information System (INIS)

    Broverman, A.Y.

    1987-11-01

    Electromagnetic forces resulting from peak pulsed current require special design consideration to prevent failure of the coils of the transformer. Procedures for interleaving transformer windings to reduce both electromagnetic short-circuit forces and reactive voltage drop while reducing procurement costs are described. The basics of transformer design principles and cost trade-offs are included to enhance understanding of the interleaving procedures. 3 refs., 3 figs

  13. Reactive documentation system

    Science.gov (United States)

    Boehnlein, Thomas R.; Kramb, Victoria

    2018-04-01

    Proper formal documentation of computer acquired NDE experimental data generated during research is critical to the longevity and usefulness of the data. Without documentation describing how and why the data was acquired, NDE research teams lose capability such as their ability to generate new information from previously collected data or provide adequate information so that their work can be replicated by others seeking to validate their research. Despite the critical nature of this issue, NDE data is still being generated in research labs without appropriate documentation. By generating documentation in series with data, equal priority is given to both activities during the research process. One way to achieve this is to use a reactive documentation system (RDS). RDS prompts an operator to document the data as it is generated rather than relying on the operator to decide when and what to document. This paper discusses how such a system can be implemented in a dynamic environment made up of in-house and third party NDE data acquisition systems without creating additional burden on the operator. The reactive documentation approach presented here is agnostic enough that the principles can be applied to any operator controlled, computer based, data acquisition system.

  14. Pulse-train control of branching processes: Elimination of background and intruder state population

    International Nuclear Information System (INIS)

    Seidl, Markus; Uiberacker, Christoph; Jakubetz, Werner; Etinski, Mihajlo

    2008-01-01

    The authors introduce and describe pulse train control (PTC) of population branching in strongly coupled processes as a novel control tool for the separation of competing multiphoton processes. Control strategies are presented based on the different responses of processes with different photonicities and/or different frequency detunings to the pulse-to-pulse time delay and the pulse-to-pulse phase shift in pulse trains. The control efficiency is further enhanced by the property of pulse trains that complete population transfer can be obtained over an extended frequency range that replaces the resonance frequency of simple pulses. The possibility to freely tune the frequency assists the separation of the competing processes and reduces the number of subpulses required for full control. As a sample application, PTC of leaking multiphoton resonances is demonstrated by numerical simulations. In model systems exhibiting sizable background (intruder) state population if excited with single pulses, PTC leading to complete accumulation of population in the target state and elimination of background population is readily achieved. The analysis of the results reveals different mechanisms of control and provides clues on the mechanisms of the leaking process itself. In an alternative setup, pulse trains can be used as a phase-sensitive tool for level switching. By changing only the pulse-to-pulse phase shift of a train with otherwise unchanged parameters, population can be transferred to any of two different target states in a near-quantitative manner.

  15. Reactivation of Rate Remapping in CA3.

    Science.gov (United States)

    Schwindel, C Daniela; Navratilova, Zaneta; Ali, Karim; Tatsuno, Masami; McNaughton, Bruce L

    2016-09-07

    The hippocampus is thought to contribute to episodic memory by creating, storing, and reactivating patterns that are unique to each experience, including different experiences that happen at the same location. Hippocampus can combine spatial and contextual/episodic information using a dual coding scheme known as "global" and "rate" remapping. Global remapping selects which set of neurons can activate at a given location. Rate remapping readjusts the firing rates of this set depending on current experience, thus expressing experience-unique patterns at each location. But can the experience-unique component be retrieved spontaneously? Whereas reactivation of recent, spatially selective patterns in hippocampus is well established, it is never perfect, raising the issue of whether the experiential component might be absent. This question is key to the hypothesis that hippocampus can assist memory consolidation by reactivating and broadcasting experience-specific "index codes" to neocortex. In CA3, global remapping exhibits attractor-like dynamics, whereas rate remapping apparently does not, leading to the hypothesis that only the former can be retrieved associatively and casting doubt on the general consolidation hypothesis. Therefore, we studied whether the rate component is reactivated spontaneously during sleep. We conducted neural ensemble recordings from CA3 while rats ran on a circular track in different directions (in different sessions) and while they slept. It was shown previously that the two directions of running result in strong rate remapping. During sleep, the most recent rate distribution was reactivated preferentially. Therefore, CA3 can retrieve patterns spontaneously that are unique to both the location and the content of recent experience. The hippocampus is required for memory of events and their spatial contexts. The primary correlate of hippocampal activity is location in space, but multiple memories can occur in the same location. To be useful

  16. PULSTRI-1 computer program for mixed core pulse calculation

    International Nuclear Information System (INIS)

    Ravnik, M.; Mele, I.; Dimic, V.

    1990-01-01

    PUISTRI-1 is a computer code designed for calculations of the pulse parameters of TRIGA Mark II reactor with mixed core. The code is provided with data for four types of fuel elements: standard 8.5 and 12 w/o, LEU and FLIP. The pulse parameters, such as maximum power, prompt pulse energy and average fuel temperatures are calculated in adiabatic point kinetics, approximation, modified by taking into account temperature dependence of fuel temperature reactivity coefficient and thermal capacity factor averaged over all elements in the core. Maximal fuel temperature at power peaking location is calculated from total released energy using total power peaking factor and heat capacity of the element at the location of the power peaking. Results of the code were compared to data found in references (mainly General Atomics safety analysis reports) showing good agreement for all main pulse parameters. The most important parameters, average and maximal fuel temperature, are found to be systematically slightly overpredicted (20 C and 50 C, respectively). Other parameters (energy, peak power, width) agree within ± 10 % to the reference values. The code is written in FORTRAN for IBM PC computer. The input is user friendly. running time of IBM PC AT is a few seconds. It is designed for practical applications in pulse experiments as an analytical tool for predicting pulse parameters. (orig.)

  17. Heteronuclear proton assisted recoupling

    Science.gov (United States)

    De Paëpe, Gaël; Lewandowski, Józef R.; Loquet, Antoine; Eddy, Matt; Megy, Simon; Böckmann, Anja; Griffin, Robert G.

    2011-03-01

    We describe a theoretical framework for understanding the heteronuclear version of the third spin assisted recoupling polarization transfer mechanism and demonstrate its potential for detecting long-distance intramolecular and intermolecular 15N-13C contacts in biomolecular systems. The pulse sequence, proton assisted insensitive nuclei cross polarization (PAIN-CP) relies on a cross term between 1H-15N and 1H-13C dipolar couplings to mediate zero- and/or double-quantum 15N-13C recoupling. In particular, using average Hamiltonian theory we derive effective Hamiltonians for PAIN-CP and show that the transfer is mediated by trilinear terms of the form N±C∓Hz (ZQ) or N±C±Hz (DQ) depending on the rf field strengths employed. We use analytical and numerical simulations to explain the structure of the PAIN-CP optimization maps and to delineate the appropriate matching conditions. We also detail the dependence of the PAIN-CP polarization transfer with respect to local molecular geometry and explain the observed reduction in dipolar truncation. In addition, we demonstrate the utility of PAIN-CP in structural studies with 15N-13C spectra of two uniformly 13C,15N labeled model microcrystalline proteins—GB1, a 56 amino acid peptide, and Crh, a 85 amino acid domain swapped dimer (MW = 2 × 10.4 kDa). The spectra acquired at high magic angle spinning frequencies (ωr/2π > 20 kHz) and magnetic fields (ω0H/2π = 700-900 MHz) using moderate rf fields, yield multiple long-distance intramonomer and intermonomer 15N-13C contacts. We use these distance restraints, in combination with the available x-ray structure as a homology model, to perform a calculation of the monomer subunit of the Crh protein.

  18. Sequentially pulsed traveling wave accelerator

    Science.gov (United States)

    Caporaso, George J [Livermore, CA; Nelson, Scott D [Patterson, CA; Poole, Brian R [Tracy, CA

    2009-08-18

    A sequentially pulsed traveling wave compact accelerator having two or more pulse forming lines each with a switch for producing a short acceleration pulse along a short length of a beam tube, and a trigger mechanism for sequentially triggering the switches so that a traveling axial electric field is produced along the beam tube in synchronism with an axially traversing pulsed beam of charged particles to serially impart energy to the particle beam.

  19. Reactive Power from Distributed Energy

    Energy Technology Data Exchange (ETDEWEB)

    Kueck, John; Kirby, Brendan; Rizy, Tom; Li, Fangxing; Fall, Ndeye

    2006-12-15

    Distributed energy is an attractive option for solving reactive power and distribution system voltage problems because of its proximity to load. But the cost of retrofitting DE devices to absorb or produce reactive power needs to be reduced. There also needs to be a market mechanism in place for ISOs, RTOs, and transmission operators to procure reactive power from the customer side of the meter where DE usually resides. (author)

  20. Reactive Power from Distributed Energy

    International Nuclear Information System (INIS)

    Kueck, John; Kirby, Brendan; Rizy, Tom; Li, Fangxing; Fall, Ndeye

    2006-01-01

    Distributed energy is an attractive option for solving reactive power and distribution system voltage problems because of its proximity to load. But the cost of retrofitting DE devices to absorb or produce reactive power needs to be reduced. There also needs to be a market mechanism in place for ISOs, RTOs, and transmission operators to procure reactive power from the customer side of the meter where DE usually resides. (author)

  1. Reactive programming in eventsourcing systems

    OpenAIRE

    Kučinskas, Žilvinas

    2017-01-01

    Eventsourcing describes current state as series of events that occurred in a system. Events hold all information that is needed to recreate current state. This method allows to achieve high volume of transactions, and enables efficient replication. Whereas reactive programming lets implement reactive systems in declarative style, decomposing logic into smaller, easier to understand components. Thesis aims to create reactive programming program interface, incorporating both principles. Applyin...

  2. Reactive Programming in Standard ML

    OpenAIRE

    Pucella, Riccardo

    2004-01-01

    Reactive systems are systems that maintain an ongoing interaction with their environment, activated by receiving input events from the environment and producing output events in response. Modern programming languages designed to program such systems use a paradigm based on the notions of instants and activations. We describe a library for Standard ML that provides basic primitives for programming reactive systems. The library is a low-level system upon which more sophisticated reactive behavi...

  3. A compact plasma pre-ionized TEA-CO2 laser pulse clipper for material processing

    Science.gov (United States)

    Gasmi, Taieb

    2017-08-01

    An extra-laser cavity CO2-TEA laser pulse clipper using gas breakdown techniques for high spatial resolution material processing and shallow material engraving and drilling processes is presented. Complete extinction of the nitrogen tail, that extends the pulse width, is obtained at pressures from 375 up to 1500 torr for nitrogen and argon gases. Excellent energy stability and pulse repeatability were further enhanced using high voltage assisted preionized plasma gas technique. Experimental data illustrates the direct correlation between laser pulse width and depth of engraving in aluminum and alumina materials.

  4. Attosecond pulse generation in noble gases in the presence of extreme high intensity THz pulses

    International Nuclear Information System (INIS)

    Balogh, E.; Varju, K.

    2010-01-01

    Complete text of publication follows. The shortest - attosecond - light pulses available today are produced by high harmonic generation (HHG) of near-infrared (NIR) laser pulses in noble gas jets, providing a broad spectral plateau of XUV radiation ending in a cutoff. The minimum pulse duration is determined by the achievable bandwidth (i.e. the position of the cutoff), and the chirp of the produced pulses. The extension of the cutoff by increasing the laser intensity is limited by the depletion and phase matching problems of the medium. An alternative method demonstrated to produce higher harmonic orders is by using longer pump pulse wavelength, with the disadvantage of decreased efficiency. Recently it was shown that application of a quasi-DC high strength electric field results in an increase of more than a factor of two in the order of efficiently generated high harmonics. However, the possibility to implement the method proposed in [3] of using a CO 2 laser to create a quasi-DC field for assisting HHG of the NIR laser is questionable, because it's technically very challenging to synchronize pulses from different laser sources. Alternatively, synchronous production of THz pulses with the NIR laser pulse offers a more promising route. The first numerical test of this idea has been reported in [4]. In this contribution we further investigate the method for realistic THz field strengths and short driving pulses, exploring the effect of longer pump laser wavelength on the process. We assume the presence of high intensity THz pulses for supplying the high-strength quasi-DC electric field. The spectrum as well as the chirp of the produced radiation is calculated. We use the non-adiabatic saddle point method to determine the generated radiation described in [6]. We simulate harmonic generation in noble gas atoms, with few cycle NIR pulses of peak intensity at and above 2 x 10 14 W/cm 2 (388 MV/cm) and wavelengths 800 nm and 1560 nm. The THz field strength is varied

  5. Pulse pile-up IV

    International Nuclear Information System (INIS)

    Wilkinson, D.H.

    1991-05-01

    The study of pulse pile-up is extended from the case of unipolar pulses, for which ruin theory is an excellent approximation, to the case of bipolar pulses for which ruin theory is not applicable to the effect of the back-kicks in reducing the pile-up: an appropriate solution is presented. (Author) 3 refs., 11 figs

  6. Positive void reactivity

    International Nuclear Information System (INIS)

    Diamond, D.J.

    1992-09-01

    This report is a review of some of the important aspects of the analysis of large loss-of-coolant accidents (LOCAs). One important aspect is the calculation of positive void reactivity. To study this subject the lattice physics codes used for void worth calculations and the coupled neutronic and thermal-hydraulic codes used for the transient analysis are reviewed. Also reviewed are the measurements used to help validate the codes. The application of these codes to large LOCAs is studied with attention focused on the uncertainty factor for the void worth used to bias the results. Another aspect of the subject dealt with in the report is the acceptance criteria that are applied. This includes the criterion for peak fuel enthalpy and the question of whether prompt criticality should also be a criterion. To study the former, fuel behavior measurements and calculations are reviewed. (Author) (49 refs., 2 figs., tab.)

  7. Massive florid reactive periostitis

    International Nuclear Information System (INIS)

    Nance, K.V.; Renner, J.B.; Brashear, H.R.; Siegal, G.P.; North Carolina Univ., Chapel Hill, NC

    1990-01-01

    Florid reactive periostitis is a rare, benign process usually occurring in the small, tubular bones of the hands and feet. Typically the lesion occurs in an adolescent or young adult and presents as a small area of pain and erythema over the affected bone. Although the histologic features may suggest malignancy, there is usually little radiographic evidence to support such a diagnosis. In the following report an unusual example of this entity is described whose large size and relentless local progression led to initial diagnostic uncertainty and eventual aggressive management. This case suggests that a wide spectrum of radiologic and morphologic changes may be seen in this entity and that a seemingly unrelated genetic disease may alter the typical clinical course. (orig.)

  8. Pembrolizumab reactivates pulmonary granulomatosis

    Directory of Open Access Journals (Sweden)

    Majdi Al-dliw

    2017-01-01

    Full Text Available Sarcoid like reaction is a well-known entity that occurs as a consequence to several malignancies or their therapies. Immunotherapy has gained a lot of interest in the past few years and has recently gained approval as first line therapy in multiple advanced stage malignancies. Pneumonitis has been described as complication of such therapy. Granulomatous inflammation has been only rarely reported subsequent to immunotherapy. We describe a case of granulomatous inflammation reactivation affecting the lungs in a patient previously exposed to Pembrolizumab and have evidence of a distant granulomatous infection. We discuss potential mechanisms of the inflammation and assert the importance of immunosuppression in controlling the dis-inhibited immune system.

  9. Reactive Oxygen Species

    DEFF Research Database (Denmark)

    Franchina, Davide G.; Dostert, Catherine; Brenner, Dirk

    2018-01-01

    T cells are a central component of defenses against pathogens and tumors. Their effector functions are sustained by specific metabolic changes that occur upon activation, and these have been the focus of renewed interest. Energy production inevitably generates unwanted products, namely reactive...... and transcription factors, influencing the outcome of the T cell response. We discuss here how ROS can directly fine-tune metabolism and effector functions of T cells....... oxygen species (ROS), which have long been known to trigger cell death. However, there is now evidence that ROS also act as intracellular signaling molecules both in steady-state and upon antigen recognition. The levels and localization of ROS contribute to the redox modeling of effector proteins...

  10. Weigle Reactivation in Acinetobacter Calcoaceticus

    DEFF Research Database (Denmark)

    Berenstein, Dvora

    1982-01-01

    phage and host survivals of about 5 times 10-6 and 1 times 10-1, respectively. Intracellular development of W-reactivated P78 was followed by one-step growth experiments. Conditions which allowed maximal W-reactivation also extended the period of phage production and yielded a somewhat reduced burst......Weigle (W)-reactivation was demonstrated in Acinetobacter calcoaceticus for the UV-irra-diated lysogenic phage P78. The reactivation factor (survival of irradiated phage on irradiated bacteria/ survival on unirradiated bacteria) reached a maximum value of 20. This was obtained at UV-doses giving...

  11. Pulsed atmospheric fluidized bed combustion

    Energy Technology Data Exchange (ETDEWEB)

    1989-11-01

    In order to verify the technical feasibility of the MTCI Pulsed Atmospheric Fluidized Bed Combustor technology, a laboratory-scale system was designed, built and tested. Important aspects of the operational and performance parameters of the system were established experimentally. A considerable amount of the effort was invested in the initial task of constructing an AFBC that would represent a reasonable baseline against which the performance of the PAFBC could be compared. A summary comparison of the performance and emissions data from the MTCI 2 ft {times} 2 ft facility (AFBC and PAFBC modes) with those from conventional BFBC (taller freeboard and recycle operation) and circulating fluidized bed combustion (CFBC) units is given in Table ES-1. The comparison is for typical high-volatile bituminous coals and sorbents of average reactivity. The values indicated for BFBC and CFBC were based on published information. The AFBC unit that was designed to act as a baseline for the comparison was indeed representative of the larger units even at the smaller scale for which it was designed. The PAFBC mode exhibited superior performance in relation to the AFBC mode. The higher combustion efficiency translates into reduced coal consumption and lower system operating cost; the improvement in sulfur capture implies less sorbent requirement and waste generation and in turn lower operating cost; lower NO{sub x} and CO emissions mean ease of site permitting; and greater steam-generation rate translates into less heat exchange surface area and reduced capital cost. Also, the PAFBC performance generally surpasses those of conventional BFBC, is comparable to CFBC in combustion and NO{sub x} emissions, and is better than CFBC in sulfur capture and CO emissions even at the scaled-down size used for the experimental feasibility tests.

  12. Thermoelastic expansion in prompt-critical neutron pulse idealized in a fissile metallic sphere

    International Nuclear Information System (INIS)

    Barroso, D.E.G.; Ribeiro, S.G.

    1985-01-01

    Prompt critical pulses in solid and homogeneous spheres of enriched uranium (93%) and metallic plutonium are studied. The feedback mechanism of the negative inserted reactivity is given by the elastic expansion due to the increase of the temperature in the sphere. Thermomechanical behavior and the capability of the system to become subcritical without a very large increase of energy released in the pulse are analysed. The neutronic and thermoelasticity equations are solved in the time. (M.C.K.) [pt

  13. Comparison between the water activation effects by pulsed and sinusoidal helium plasma jets

    Science.gov (United States)

    Xu, Han; Liu, Dingxin; Xia, Wenjie; Chen, Chen; Wang, Weitao; Liu, Zhijie; Wang, Xiaohua; Kong, Michael G.

    2018-01-01

    Comparisons between pulsed and sinusoidal plasma jets have been extensively reported for the discharge characteristics and gaseous reactive species, but rarely for the aqueous reactive species in water solutions treated by the two types of plasma jets. This motivates us to compare the concentrations of aqueous reactive species induced by a pulsed and a sinusoidal plasma jet, since it is widely reported that these aqueous reactive species play a crucial role in various plasma biomedical applications. Experimental results show that the aqueous H2O2, OH/O2-, and O2-/ONOO- induced by the pulsed plasma jet have higher concentrations, and the proportional difference increases with the discharge power. However, the emission intensities of OH(A) and O(3p5P) are higher for the sinusoidal plasma jet, which may be attributed to its higher gas temperature since more water vapor could participate in the plasma. In addition, the efficiency of bacterial inactivation induced by the pulsed plasma jet is higher than that for the sinusoidal plasma jet, in accordance with the concentration relation of aqueous reactive species for the two types of plasma jets.

  14. Pulse counting period meter output during startup transients

    International Nuclear Information System (INIS)

    Cummins, J.D.

    1962-12-01

    The time response of a period meter whose input signal comes from a pulse counting channel may be calculated using a Ferranti Mercury autocode programme details of which are given. The period meter considered is the type for which the logarithmic characteristic is approximated by several diode pump circuits. The input excitation is a terminated ramp of reactivity. Other reactivity inputs may be treated. In particular the step change of reactivity may be used as the input excitation. Allowance is made for the effective time constants of the diode pump circuits and the period meter. The programme may be used for instrument assessment and for safety and operations studies on reactors which use this type of period meter. An example of the use of the programme is given. (author)

  15. Pulsed electron beam generation with fast repetitive double pulse system

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Surender Kumar; Deb, Pankaj; Shyam, Anurag, E-mail: surender80@gmail.com [Energetics and Electromagnetics Division, Bhabha Atomic Research Centre, Visakhapatnam (India); Sharma, Archana [Accelerator and Pulse Power Division, Bhabha Atomic Research Centre, Mumbai (India)

    2014-07-01

    Longer duration high voltage pulse (∼ 100 kV, 260 ns) is generated and reported using helical pulse forming line in compact geometry. The transmission line characteristics of the helical pulse forming line are also used to develop fast repetition double pulse system with very short inter pulse interval. It overcomes the limitations caused due to circuit parameters, power supplies and load characteristics for fast repetitive high voltage pulse generation. The high voltage double pulse of 100 kV, 100 ns with an inter pulse repetition interval of 30 ns is applied across the vacuum field emission diode for pulsed electron beam generation. The electron beam is generated from cathode material by application of negative high voltage (> 100 kV) across the diode by explosive electron emission process. The vacuum field emission diode is made of 40 mm diameter graphite cathode and SS mesh anode. The anode cathode gap was 6 mm and the drift tube diameter was 10 cm. The initial experimental results of pulsed electron beam generation with fast repetitive double pulse system are reported and discussed. (author)

  16. Pulsed current generator

    International Nuclear Information System (INIS)

    Semenov, V.D.; Furman, Eh.G.

    1974-01-01

    The paper describes a current pulse generator with an auxiliary network consisting of a choke and diode in series designed to enlarge the range of pulse frequency control. One output of the network is connected to an adjustable valve cathode and via antoher auxiliary condenser to the point where the cathode of the main key unit is joined to the start of the magnetizing coil. A second output is connected to the anode of another adjustable valve and via another auxiliary condenser to the point where the anode of the other main key unit is joined to the end of the magnetizing coil. The generator can be used to excite the electromagnets of charged particle accelerators or in devices designed to produce magnetic fields. (author)

  17. Fast pulse amplifier

    International Nuclear Information System (INIS)

    Lepetit, J.; Poussier, E.

    1984-01-01

    This amplifier comprises an inverter transformer, the primary circuit of which receives a pulse and the secondary circuit of which is connected to several amplifying elements in parallel. The inverter transformer is made of coaxial cable segments winded around a magnetic torus; the cable cores connected in series constitute the primary circuit and the braiding of cables, connected in parallel, are the secondary circuit. The transformer comprises, besides, delay lines in series with each braiding of the secondary circuit, these ones are such that pulses issued from each braiding arrive together to the secondary circuit connectors. This invention applies, noticeably in the case of a high voltage amplifier, to the control of deflection blocks of particles used in medicine or in particle accelerators [fr

  18. Linear pulse amplifier

    International Nuclear Information System (INIS)

    Tjutju, R.L.

    1977-01-01

    Pulse amplifier is standard significant part of spectrometer. Apart from other type of amplification, it's a combination of amplification and pulse shaping. Because of its special purpose the device should fulfill the following : High resolution is desired to gain a high yield comparable to its actual state of condition. High signal to noise is desired to nhν resolution. High linearity to facilitate calibration. A good overload recovery, in order to the device will capable of analizing a low energy radiation which appear joinly on the high energy fields. Other expections of the device are its economical and practical use its extentive application. For that reason it's built on a standard NIM principle. Taking also into account the above mentioned considerations. High quality component parts are used throughout, while its availability in the domestic market is secured. (author)

  19. Pulsed fusion reactors

    International Nuclear Information System (INIS)

    1975-01-01

    This summer school specialized in examining specific fusion center systems. Papers on scientific feasibility are first presented: confinement of high-beta plasma, liners, plasma focus, compression and heating and the use of high power electron beams for thermonuclear reactors. As for technological feasibility, lectures were on the theta-pinch toroidal reactors, toroidal diffuse pinch, electrical engineering problems in pulsed magnetically confined reactors, neutral gas layer for heat removal, the conceptual design of a series of laser fusion power plants with ''Saturn'', implosion experiments and the problem of the targets, the high brightness lasers for plasma generation, and topping and bottoming cycles. Some problems common to pulsed reactors were examined: energy storage and transfer, thermomechanical and erosion effects in the first wall and blanket, the problems of tritium production, radiation damage and neutron activation in blankets, and the magnetic and inertial confinement

  20. Short pulse neutron generator

    Science.gov (United States)

    Elizondo-Decanini, Juan M.

    2016-08-02

    Short pulse neutron generators are described herein. In a general embodiment, the short pulse neutron generator includes a Blumlein structure. The Blumlein structure includes a first conductive plate, a second conductive plate, a third conductive plate, at least one of an inductor or a resistor, a switch, and a dielectric material. The first conductive plate is positioned relative to the second conductive plate such that a gap separates these plates. A vacuum chamber is positioned in the gap, and an ion source is positioned to emit ions in the vacuum chamber. The third conductive plate is electrically grounded, and the switch is operable to electrically connect and disconnect the second conductive plate and the third conductive plate. The at least one of the resistor or the inductor is coupled to the first conductive plate and the second conductive plate.

  1. Pulsed rf operation analysis

    International Nuclear Information System (INIS)

    Puglisi, M.; Cornacchia, M.

    1981-01-01

    The need for a very low final amplifier output impedance, always associated with class A operation, requires a very large power waste in the final tube. The recently suggested pulsed rf operation, while saving a large amount of power, increases the inherent final amplifier non linearity. A method is presented for avoiding the large signal non linear analysis and it is shown how each component of the beam induced voltage depends upon all the beam harmonics via some coupling coefficients which are evaluated

  2. PULSE Pilot Certification Results

    Directory of Open Access Journals (Sweden)

    Pamela Pape-Lindstrom

    2015-08-01

    Full Text Available The pilot certification process is an ambitious, nationwide endeavor designed to motivate important changes in life sciences education that are in line with the recommendations of the 2011 Vision and Change Report: A Call to Action (American Association for the Advancement of Science [AAAS], 2011.  It is the goal of the certification process to acknowledge departments that have progressed towards full implementation of the tenets of Vision and Change and to motivate departments that have not begun to adopt the recommendations to consider doing so.  More than 70 life science departments applied to be part of the pilot certification process, funded by a National Science Foundation grant, and eight were selected based on initial evidence of transformed and innovative educational practices.  The programs chosen represent a wide variety of schools, including two-year colleges, liberal-arts institutions, regional comprehensive colleges, research universities and minority serving institutions.  Outcomes from this pilot were released June 1, 2015 (www.pulsecommunity.org, with all eight programs being recognized as having progressed along a continuum of change.  Five levels of achievement were defined as PULSE Pilot Progression Levels.  Of the eight departments in the pilot, one achieved “PULSE Progression Level III: Accomplished”.  Six departments achieved “PULSE Progression Level II: Developing” and one pilot department achieved “PULSE Progression Level I: Beginning”.  All of the schools have made significant movement towards the recommendations of Vision and Change relative to a traditional life sciences curriculum.  Overall, the response from the eight pilot schools has been positive. 

  3. STUCTURE OF PULSED BED

    Directory of Open Access Journals (Sweden)

    I. A. Bokun

    2014-01-01

    Full Text Available The structure of pulsed layer is proposed which can be suggested as a state of particulates that is blown by intermittent gas flow with speed which has the force to start material moving. Layer during one cycle is in a suspension, falling down and immobile state resulting in changes of particles arrangement as well as ways of gas flowing through layer. Moreover, it allows carrying out effective interphase heat exchange even adamant real granulation.The process of formation of impact flows is considered aw well as their influence on formation of air bubbles in pulsed layer. At startup of air blast the balance between the force of hydro-dynamic resistance is broken, on one side, and forces of gravity, particles inertia and their links with walls on the other side. The layer is transferred in the state of pulsed pseudo-fluidization, and presents gas-disperse mixture, inside of which impulse of pressure increasing is spreading to all sides as pressure waves (compression. These waves are the sources of impact flows’ formation, the force of which is two times more than during the stationary flow.The waves of pressure are divided into weak and strong ones depending on movement velocity within gas-disperse system. Weak waves are moving with a sound speed and strong ones in active phase of pulsed layer are moving over the speed of sound limit within gas-disperse system. The peculiarity of strong wave is that parameters of system (pressure, density and others are changing in discrete steps.The article describes the regime of layer’s falling down in the passive stage of cycle, which begins after finishing of gas impulse action. And suspension layer of moving up granular material is transferred in the state of falling resulting in change of the layer structure.

  4. Downhole pulse radar

    Science.gov (United States)

    Chang, Hsi-Tien

    1987-09-28

    A borehole logging tool generates a fast rise-time, short duration, high peak-power radar pulse having broad energy distribution between 30 MHz and 300 MHz through a directional transmitting and receiving antennas having barium titanate in the electromagnetically active region to reduce the wavelength to within an order of magnitude of the diameter of the antenna. Radar returns from geological discontinuities are sampled for transmission uphole. 7 figs.

  5. Pulse radiolysis of gases

    International Nuclear Information System (INIS)

    Nielsen, O.J.

    1984-04-01

    The pulse radiolysis equipment and technique are described and its relevance to atmospheric chemistry is discussed. Pulse radiolysis of a number of different chemical systems have been used to check the validity of the proposed mechanisms: 1) The hydrogen atom yield in the pulse radiolysis of H 2 was measured by four independent calibration techniques, using reactions of H with O 2 , C1NO, and HI. The H atom yield was compared with O 2 yields in pure O 2 and in O 2 /SF 6 mixtures which lead to a value G(H) = 17.6. The rate constants at room temperature of several reactions were determined. 2) OH radical reactions with tetraalkyllead at room temperature and with ethane, methane, and a series of C1- and F-substituted methanes at 300-400 K were studied. Arrhenius parameters, A and Esub(a), were determined for several reactions. The lifetime of Pb(CH 3 ) 4 and Pb(C 2 H 5 ) 4 in ambient air is estimated. CF 2 C1 2 was found to be a very efficient third body, M, in the reaction OH + OH + M arrow H 2 O 2 + M. 3) In the H 2 S systems the HS extinction coefficient at 3242 AA was determined to 9.5 x 10 2 cm -1 mol -1 . Four rate constants at room temperature were determined. (author)

  6. Comparison of power pulses from homogeneous and time-average-equivalent models

    International Nuclear Information System (INIS)

    De, T.K.; Rouben, B.

    1995-01-01

    The time-average-equivalent model is an 'instantaneous' core model designed to reproduce the same three dimensional power distribution as that generated by a time-average model. However it has been found that the time-average-equivalent model gives a full-core static void reactivity about 8% smaller than the time-average or homogeneous models. To investigate the consequences of this difference in static void reactivity in time dependent calculations, simulations of the power pulse following a hypothetical large-loss-of-coolant accident were performed with a homogeneous model and compared with the power pulse from the time-average-equivalent model. The results show that there is a much smaller difference in peak dynamic reactivity than in static void reactivity between the two models. This is attributed to the fact that voiding is not complete, but also to the retardation effect of the delayed-neutron precursors on the dynamic flux shape. The difference in peak reactivity between the models is 0.06 milli-k. The power pulses are essentially the same in the two models, because the delayed-neutron fraction in the time-average-equivalent model is lower than in the homogeneous model, which compensates for the lower void reactivity in the time-average-equivalent model. (author). 1 ref., 5 tabs., 9 figs

  7. Petawatt pulsed-power accelerator

    Science.gov (United States)

    Stygar, William A.; Cuneo, Michael E.; Headley, Daniel I.; Ives, Harry C.; Ives, legal representative; Berry Cottrell; Leeper, Ramon J.; Mazarakis, Michael G.; Olson, Craig L.; Porter, John L.; Wagoner; Tim C.

    2010-03-16

    A petawatt pulsed-power accelerator can be driven by various types of electrical-pulse generators, including conventional Marx generators and linear-transformer drivers. The pulsed-power accelerator can be configured to drive an electrical load from one- or two-sides. Various types of loads can be driven; for example, the accelerator can be used to drive a high-current z-pinch load. When driven by slow-pulse generators (e.g., conventional Marx generators), the accelerator comprises an oil section comprising at least one pulse-generator level having a plurality of pulse generators; a water section comprising a pulse-forming circuit for each pulse generator and a level of monolithic triplate radial-transmission-line impedance transformers, that have variable impedance profiles, for each pulse-generator level; and a vacuum section comprising triplate magnetically insulated transmission lines that feed an electrical load. When driven by LTD generators or other fast-pulse generators, the need for the pulse-forming circuits in the water section can be eliminated.

  8. Foundations of pulsed power technology

    CERN Document Server

    Lehr, Janet

    2018-01-01

    Pulsed power technologies could be an answer to many cutting-edge applications. The challenge is in how to develop this high-power/high-energy technology to fit current market demands of low-energy consuming applications. This book provides a comprehensive look at pulsed power technology and shows how it can be improved upon for the world of today and tomorrow. Foundations of Pulsed Power Technology focuses on the design and construction of the building blocks as well as their optimum assembly for synergetic high performance of the overall pulsed power system. Filled with numerous design examples throughout, the book offers chapter coverage on various subjects such as: Marx generators and Marx-like circuits; pulse transformers; pulse-forming lines; closing switches; opening switches; multi-gigawatt to multi-terawatt systems; energy storage in capacitor banks; electrical breakdown in gases; electrical breakdown in solids, liquids and vacuum; pulsed voltage and current measurements; electromagnetic interferen...

  9. Pulsed neutron source very intense, Booster

    International Nuclear Information System (INIS)

    Abbate, J.M.

    1978-09-01

    A compact Accelerator-Booster (fast, pulsed and modulate reactivity research reactor) is a new and appropriate conception to use as a very intense thermal neutrons source. Its definition and feasibility have been already described in several studies showing its relative advantages in comparison with others kinds of facilities. This work, wich is part of one of those studies, contains a general analysis on the meis facility parameters and core and shielding theoretical calculations. The following results were obtained: Selection and test of a calculation system suitable to use in compact fast reactors; Development a method to perform estimations in some safety and shielding problems and obtainment of adequate theoretical predictions on the general performance. Moreover, final results for importent parameters of the feasibility study and predesign (critical mass and volume, lifetime, etc.) and others related to the use of plutonium oxide as fuel are given and then evaluations of different basic functions are showed. (author) [es

  10. Electron transfer reactivity of the Arabidopsis thaliana sulfhydryl oxidase AtErv1

    DEFF Research Database (Denmark)

    Farver, Ole; Vitu, Elvira; Wherland, Scot

    2009-01-01

    The redox reactivity of the three disulfide bridges and the flavin present in each protomer of the wild-type Arabidopsis thaliana mitochondrial sulfhydryl oxidase (AtErv1) homodimer has been investigated. Pulse radiolytically produced CO2- radical ions were found to reduce the disulfide bridges...

  11. Engagement, resilience and empathy in nursing assistants.

    Science.gov (United States)

    Navarro-Abal, Yolanda; López-López, M José; Climent-Rodríguez, José A

    To analyse the levels of engagement, resilience and empathy, and the relationship between them, in a sample of nursing assistants working in different private institutions in Huelva. A transversal, descriptive study. The sample comprised 128 nursing assistants working in private health centres of Huelva. They were given the following instruments: resilience scale Wagnild and Young, Interpersonal Reactivity Index and Utrech Work Engagement Scale. There is a relationship between the cognitive and emotional components of engagement and empathy. Certain sociodemographic variables associated with the organisation of work and working conditions are associated with level of engagement. Copyright © 2017 Elsevier España, S.L.U. All rights reserved.

  12. Regarding KUR Reactivity Measurement System

    International Nuclear Information System (INIS)

    Nakamori, Akira; Hasegawa, Kei; Tsuchiyama, Tatsuo; Yamamoto, Toshihiro; Okumura, Ryo; Sano, Tadafumi

    2012-01-01

    This article reported: (1) the outline of the reactivity measurement system of Kyoto University Research Reactor (KUR), (2) the calibration data of control rod, (3) the problems and the countermeasures for range switching of linear output meter. For the laptop PC for the reactivity measurement system, there are four input signals: (1) linear output meter, (2) logarithmic output meter, (3) core temperature gauge, and (4) control rod position. The hardware of reactivity measurement system is controlled with Labview installed on the laptop. Output, reactivity, reactor period, and the change in reactivity due to temperature effect or Xenon effect are internally calculated and displayed in real-time with Labview based on the four signals above. Calculation results are recorded in the form of a spreadsheet. At KUR, the reactor core arrangement was changed, so the control rod was re-calibrated. At this time, calculated and experimental values of reactivity based on the reactivity measurement system were compared, and it was confirmed that the reactivity calculation by Labview was accurate. The range switching of linear output meter in the nuclear instrumentation should automatically change within the laptop, however sometimes this did not function properly in the early stage. It was speculated that undefined percent values during the transition of percent value were included in the calculation and caused calculation errors. The range switching started working properly after fixing this issue. (S.K.)

  13. Reactive agents and perceptual ambiguity

    NARCIS (Netherlands)

    Dartel, M. van; Sprinkhuizen-Kuyper, I.G.; Postma, E.O.; Herik, H.J. van den

    2005-01-01

    Reactive agents are generally believed to be incapable of coping with perceptual ambiguity (i.e., identical sensory states that require different responses). However, a recent finding suggests that reactive agents can cope with perceptual ambiguity in a simple model (Nolfi, 2002). This paper

  14. Assisted Vaginal Delivery

    Science.gov (United States)

    ... Education & Events Advocacy For Patients About ACOG Assisted Vaginal Delivery Home For Patients Search FAQs Assisted Vaginal ... Vaginal Delivery FAQ192, February 2016 PDF Format Assisted Vaginal Delivery Labor, Delivery, and Postpartum Care What is ...

  15. A Tariff for Reactive Power

    Energy Technology Data Exchange (ETDEWEB)

    Kueck, John D [ORNL; Kirby, Brendan J [ORNL; Li, Fangxing [ORNL; Tufon, Christopher [Pacific Gas and Electric Company; Isemonger, Alan [California Independent System Operator

    2008-07-01

    Two kinds of power are required to operate an electric power system: real power, measured in watts, and reactive power, measured in volt-amperes reactive or VARs. Reactive power supply is one of a class of power system reliability services collectively known as ancillary services, and is essential for the reliable operation of the bulk power system. Reactive power flows when current leads or lags behind voltage. Typically, the current in a distribution system lags behind voltage because of inductive loads such as motors. Reactive power flow wastes energy and capacity and causes voltage droop. To correct lagging power flow, leading reactive power (current leading voltage) is supplied to bring the current into phase with voltage. When the current is in phase with voltage, there is a reduction in system losses, an increase in system capacity, and a rise in voltage. Reactive power can be supplied from either static or dynamic VAR sources. Static sources are typically transmission and distribution equipment, such as capacitors at substations, and their cost has historically been included in the revenue requirement of the transmission operator (TO), and recovered through cost-of-service rates. By contrast, dynamic sources are typically generators capable of producing variable levels of reactive power by automatically controlling the generator to regulate voltage. Transmission system devices such as synchronous condensers can also provide dynamic reactive power. A class of solid state devices (called flexible AC transmission system devices or FACTs) can provide dynamic reactive power. One specific device has the unfortunate name of static VAR compensator (SVC), where 'static' refers to the solid state nature of the device (it does not include rotating equipment) and not to the production of static reactive power. Dynamic sources at the distribution level, while more costly would be very useful in helping to regulate local voltage. Local voltage regulation would

  16. Canine assisted reading

    OpenAIRE

    Sever, Jerneja

    2016-01-01

    The diploma thesis presents various aspects of animals included in animal-assisted interventions. In theoretical part, I introduced different possible ways of animal-assisted interventions: animal-assisted therapy, animal-assisted activities and animal-assisted education. Animals became common visitors in educational settings all over the world. I presented positive influences on various aspects of human life, as well limitations when animal-assisted interventions are not possible to perform ...

  17. PROCEEDINGS: MULTIPOLLUTANT SORBENT REACTIVITY ...

    Science.gov (United States)

    The report is a compilation of technical papers and visual aids presented by representatives of industry, academia, and government agencies at a workshop on multipollutant sorbent reactivity that was held at EPA's Environmental Research Center in Research Triangle Park, NC, on July 19-20, 1994. There were 16 technical presentations in three sessions, and a panel discussion between six research experts. The workshop was a forum for the exchange of ideas and information on the use of sorbents to control air emissions of acid gases (sulfur dioxide, nitrogen oxides, and hydrogen chloride); mercury and dioxins; and toxic metals, primarily from fossil fuel combustion. A secondary purpose for conducting the workshop was to help guide EPA's research planning activities. A general theme of the workshop was that a strategy of controlling many pollutants with a single system rather than systems to control individual pollutants should be a research goal. Some research needs cited were: hazardous air pollutant removal by flue gas desulfurization systems, dioxin formation and control, mercury control, waste minimization, impact of ash recycling on metals partitioning, impact of urea and sorbents on other pollutants, high temperature filtration, impact of coal cleaning on metals partitioning, and modeling dispersion of sorbents in flue gas. information

  18. Reactivation with productivity

    International Nuclear Information System (INIS)

    Garcia, Carlos Hernando

    2002-01-01

    A market to five years that it will move near $63.000 millions, starting from the production of 254.000 reserves that Ecopetrol requires for its maintenance and operation, it was projected with base in the offer study and it demands that they carried out the universities Javeriana and Industrial of Santander for the Colombian Company of Petroleum around the metal mechanic sector. In accordance with the figures of the report, Ecopetrol, like one of the state entities selected by the national government to design pilot programs, guided to reactivate the Colombian industry; it is projecting a good perspective for the Colombian economy and the invigoration of the national productive sector. In practical terms, the report points out that Ecopetrol, in its different operative centers, will require in next five years the quantity of had restored before mentioned in the lines of mechanical stamps, centrifugal bombs, inter chambers of heat, compressors and valves of security; pieces that are elaborated by international makers in 99%. To produce them nationally would represent to the company an economy of 52% of the total value of the purchases in next five years and a reduction of time of delivery of 17 weeks to one week

  19. PulseCam: high-resolution blood perfusion imaging using a camera and a pulse oximeter.

    Science.gov (United States)

    Kumar, Mayank; Suliburk, James; Veeraraghavan, Ashok; Sabharwal, Ashutosh

    2016-08-01

    Measuring blood perfusion is important in medical care as an indicator of injury and disease. However, currently available devices to measure blood perfusion like laser Doppler flowmetry are bulky, expensive, and cumbersome to use. An alternative low-cost and portable camera-based blood perfusion measurement system has recently been proposed, but such camera-only system produces noisy low-resolution blood perfusion maps. In this paper, we propose a new multi-sensor modality, named PulseCam, for measuring blood perfusion by combining a traditional pulse oximeter with a video camera in a unique way to provide low noise and high-resolution blood perfusion maps. Our proposed multi-sensor modality improves per pixel signal to noise ratio of measured perfusion map by up to 3 dB and improves the spatial resolution by 2 - 3 times compared to best known camera-only methods. Blood perfusion measured in the palm using our PulseCam setup during a post-occlusive reactive hyperemia (PORH) test replicates standard PORH response curve measured using laser Doppler flowmetry device but with much lower cost and a portable setup making it suitable for further development as a clinical device.

  20. Development of the pulse transformer for NLC klystron pulse modulator

    International Nuclear Information System (INIS)

    Akemoto, M.; Gold, S.; Koontz, R.; Krasnykh, A.

    1997-05-01

    We have studied a conventional pulse transformer for the NLC klystron pulse modulator. The transformer has been analyzed using a simplified lumped circuit model. It is found that a fast rise time requires low leakage inductance and low distributed capacitance and can be realized by reducing the number of secondary turns, but it produces larger pulse droop and core size. After making a tradeoff among these parameters carefully, a conventional pulse transformer with a rise time of 250ns and pulse droop of 3.6% has been designed and built. The transmission characteristics and pulse time-response were measured. The data were compared with the model. The agreement with the model was good when the measured values were used in the model simulation. The results of the high voltage tests are also presented

  1. Pulse transformer R and D for NLC klystron pulse modulator

    International Nuclear Information System (INIS)

    Akemoto, M.; Gold, S.; Krasnykh, A.; Koontz, R.

    1997-07-01

    The authors have studied a conventional pulse transformer for the NLC klystron pulse modulator. The transformer has been analyzed using a simplified lumped circuit model. It is found that a fast rise time requires low leakage inductance and low distributed capacitance and can be realized by reducing the number of secondary turns, but it produces larger pulse droop and requires a larger core size. After making a tradeoff among these parameters carefully, a conventional pulse transformer with a rise time of 250ns and a pulse droop of 3.6% has been designed and built. The transmission characteristics and pulse time-response were measured. The data were compared with the model. The agreement with the model was good when the measured values were used in the model simulation. The results of the high voltage tests using a klystron load are also presented

  2. Coiled transmission line pulse generators

    Science.gov (United States)

    McDonald, Kenneth Fox

    2010-11-09

    Methods and apparatus are provided for fabricating and constructing solid dielectric "Coiled Transmission Line" pulse generators in radial or axial coiled geometries. The pour and cure fabrication process enables a wide variety of geometries and form factors. The volume between the conductors is filled with liquid blends of monomers, polymers, oligomers, and/or cross-linkers and dielectric powders; and then cured to form high field strength and high dielectric constant solid dielectric transmission lines that intrinsically produce ideal rectangular high voltage pulses when charged and switched into matched impedance loads. Voltage levels may be increased by Marx and/or Blumlein principles incorporating spark gap or, preferentially, solid state switches (such as optically triggered thyristors) which produce reliable, high repetition rate operation. Moreover, these Marxed pulse generators can be DC charged and do not require additional pulse forming circuitry, pulse forming lines, transformers, or an a high voltage spark gap output switch. The apparatus accommodates a wide range of voltages, impedances, pulse durations, pulse repetition rates, and duty cycles. The resulting mobile or flight platform friendly cylindrical geometric configuration is much more compact, light-weight, and robust than conventional linear geometries, or pulse generators constructed from conventional components. Installing additional circuitry may accommodate optional pulse shape improvements. The Coiled Transmission Lines can also be connected in parallel to decrease the impedance, or in series to increase the pulse length.

  3. High current transistor pulse generator

    International Nuclear Information System (INIS)

    Nesterov, V.; Cassel, R.

    1991-05-01

    A solid state pulse generator capable of delivering high current trapezoidally shaped pulses into an inductive load has been developed at SLAC. Energy stored in the capacitor bank of the pulse generator is switched to the load through a pair of Darlington transistors. A combination of diodes and Darlington transistors is used to obtain trapezoidal or triangular shaped current pulses into an inductive load and to recover the remaining energy in the same capacitor bank without reversing capacitor voltage. The transistors work in the switch mode, and the power losses are low. The rack mounted pulse generators presently used at SLAC contain a 660 microfarad storage capacitor bank and can deliver 400 amps at 800 volts into inductive loads up to 3 mH. The pulse generators are used in several different power systems, including pulse to pulse bipolar power supplies and in application with current pulses distributed into different inductive loads. The current amplitude and discharge time are controlled by the central computer system through a specially developed multichannel controller. Several years of operation with the pulse generators have proven their consistent performance and reliability. 8 figs

  4. Versatile pulse programmer for pulsed nuclear magnetic resonance spectroscopy

    International Nuclear Information System (INIS)

    Adduci, D.J.

    1979-05-01

    A description of the sequence of events and the decisions leading to the design of a versatile pulse programmer for pulsed NMR are presented. Background and application information is discussed in order that the reader might better understand the role of the pulse programmer in a NMR spectrometer. Various other design approaches are presented as a basis for comparison. Specifications for this design are proposed, the hardware implementation of the specifications is discussed, and the software operating system is presented

  5. Versatile pulse programmer for pulsed nuclear magnetic resonance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Adduci, D.J.

    1979-05-01

    A description of the sequence of events and the decisions leading to the design of a versatile pulse programmer for pulsed NMR are presented. Background and application information is discussed in order that the reader might better understand the role of the pulse programmer in a NMR spectrometer. Various other design approaches are presented as a basis for comparison. Specifications for this design are proposed, the hardware implementation of the specifications is discussed, and the software operating system is presented.

  6. Pulsed power for fusion

    International Nuclear Information System (INIS)

    Martin, T.H.

    1976-01-01

    A review which traces the development of high power pulsed accelerators from the original inception at the Atomic Weapons Research Establishment, Aldermaston, England, for Bremsstrahlung output, through the low impedance accelerators, to the double-sided accelerators for fusion will be given. Proto II is presently being assembled at Sandia and preliminary testing on the Marx has been completed. Examples of various techniques will be shown from Sandia accelerators. Requirements for accelerators capable of achieving fusion levels will be developed and problem areas outlined. The diode insulator flashover problem presently limits the maximum current available from the accelerators

  7. A Pulsed Sphere Tutorial

    Energy Technology Data Exchange (ETDEWEB)

    Cullen, Dermott E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-01-30

    Here I attempt to explain what physically happens when we pulse an object with neutrons, specifically what we expect the time dependent behavior of the neutron population to look like. Emphasis is on the time dependent emission of both prompt and delayed neutrons. I also describe how the TART Monte Carlo transport code models this situation; see the appendix for a complete description of the model used by TART. I will also show that, as we expect, MCNP and MERCURY, produce similar results using the same delayed neutron model (again, see the appendix).

  8. PULSE SYNTHESIZING GENERATOR

    Science.gov (United States)

    Kerns, Q.A.

    1963-08-01

    >An electronlc circuit for synthesizing electrical current pulses having very fast rise times includes several sinewave generators tuned to progressively higher harmonic frequencies with signal amplitudes and phases selectable according to the Fourier series of the waveform that is to be synthesized. Phase control is provided by periodically triggering the generators at precisely controlled times. The outputs of the generators are combined in a coaxial transmission line. Any frequency-dependent delays that occur in the transmission line can be readily compensated for so that the desired signal wave shape is obtained at the output of the line. (AEC)

  9. Charge pulse preamplifier

    International Nuclear Information System (INIS)

    Libs, Gerard.

    1973-01-01

    A charge pulse preamplifier with very low background noise is described. The inlet stage of that preamplifier comprises a cooled field-effect transistor receiving the signal to be amplified at its gate input. Preferably, the charge resistor of said transistor is a field effect transistor, the source inlet of which is connected to the drain inlet of the former transistor through a self-induction coil and a resistor mounted in series. This can be applied to the treatment of the signals delivered by a particle detector in the form of a semi-conductor [fr

  10. Narrowband pulse-enhanced upconversion of chirped broadband pulses

    International Nuclear Information System (INIS)

    Zhao, Kun; Yuan, Peng; Zhong, Haizhe; Zhang, Dongfang; Zhu, Heyuan; Qian, Liejia; Chen, Liezun; Wen, Shuangchun

    2010-01-01

    We propose and demonstrate an efficient sum-frequency mixing scheme based on narrowband and chirped broadband pulses. It combines the advantages of wider spectral acceptance bandwidth and of alleviating the temporal walk-off, which are both beneficial to higher conversion efficiency. Chirped sum-frequency pulses at 455 nm with energy up to 360 µJ, corresponding to a conversion efficiency of ∼ 40%, are obtained and the pulses can be compressed to ∼ 110 fs. The sum-frequency mixing scheme may provide a promising route to the efficient generation of deep-ultraviolet femtosecond pulses

  11. Supercoherent phenomena in pulsed power

    International Nuclear Information System (INIS)

    O'Rourke, R.C.

    1983-01-01

    This chapter proposes the formulation of programs of basic physics research to transform Pulsed Power Technology (PPT) to Pulsed Power Science and Technology (PPS and T) by formulating the laws of the quantized microscopic electromagnetic field; applying the microscopic electromagnetic field theory to the generation, propagation and deposition of pulses in nonlinear networks; learning more about the basic super coherent ''micro-structure'' in space and time of the many-photon states of pulsed laser beams; learning more about the basic super coherent ''micro-structure'' in space and time of the many-electronstates of pulsed electron and ion laser beams; and learning everything about the ''micro-picture'' of so-called ''dielectric breakdown'' and the associated absolute time delays. Promotes the idea that laser, electron and ion beams are similar kinds of pulses in the microscopic electromagnetic field. Presents expression for the microscopic electromagnetic field in order to show the role of supercoherence in PPS and T

  12. Present art of reactivity determination

    International Nuclear Information System (INIS)

    Kaneko, Yoshihiko; Nakano, Masafumi; Matsuura, Shojiro

    1977-01-01

    Experimental techniques for reactivity determination of a reactor have been one of the long standing subjects in reactor physics. Recently, such a requirement was proposed by the reactor designers and operators that the values of reactivity should be measured more accurately. This is because importance is emphasized for the role of reactivity to the performance of reactor safety, economics and operability. Motivated by the requirement, some remarkable progresses are being made for the improvement of the experimental techniques. Then, the present review summarizes the research activities on this subject, identifies several reactor physics problems to be overcome, and makes mention of the future targets. (auth.)

  13. Bipolar pulse forming line

    Science.gov (United States)

    Rhodes, Mark A.

    2008-10-21

    A bipolar pulse forming transmission line module for linear induction accelerators having first, second, third, fourth, and fifth planar conductors which form an interleaved stack with dielectric layers between the conductors. Each conductor has a first end, and a second end adjacent an acceleration axis. The first and second planar conductors are connected to each other at the second ends, the fourth and fifth planar conductors are connected to each other at the second ends, and the first and fifth planar conductors are connected to each other at the first ends via a shorting plate adjacent the first ends. The third planar conductor is electrically connectable to a high voltage source, and an internal switch functions to short a high voltage from the first end of the third planar conductor to the first end of the fourth planar conductor to produce a bipolar pulse at the acceleration axis with a zero net time integral. Improved access to the switch is enabled by an aperture through the shorting plate and the proximity of the aperture to the switch.

  14. Heat driven pulse pump

    Science.gov (United States)

    Benner, Steve M (Inventor); Martins, Mario S. (Inventor)

    2000-01-01

    A heat driven pulse pump includes a chamber having an inlet port, an outlet port, two check valves, a wick, and a heater. The chamber may include a plurality of grooves inside wall of the chamber. When heated within the chamber, a liquid to be pumped vaporizes and creates pressure head that expels the liquid through the outlet port. As liquid separating means, the wick, disposed within the chamber, is to allow, when saturated with the liquid, the passage of only liquid being forced by the pressure head in the chamber, preventing the vapor from exiting from the chamber through the outlet port. A plurality of grooves along the inside surface wall of the chamber can sustain the liquid, which is amount enough to produce vapor for the pressure head in the chamber. With only two simple moving parts, two check valves, the heat driven pulse pump can effectively function over the long lifetimes without maintenance or replacement. For continuous flow of the liquid to be pumped a plurality of pumps may be connected in parallel.

  15. Compensated pulsed alternator

    International Nuclear Information System (INIS)

    Weldon, W.F.; Driga, M.D.; Woodson, H.H.

    1980-01-01

    This invention relates to an electromechanical energy converter with inertial energy storage. The device, a single phase, two or multi-pole alternator with stationary field coils, and a rotating armature is provided. The rotor itself may be of laminated steel for slower pulses or for faster pulses should be nonmagnetic and electrically nonconductive in order to allow rapid penetration of the field as the armature coil rotates. The armature coil comprises a plurality of power generating conductors mounted on the rotor. The alternator may also include a stationary or counterrotating compensating coil to increase the output voltage thereof and to reduce the internal impedance of the alternator at the moment of peak output. As the machine voltage rises sinusoidally, an external trigger switch is adapted to be closed at the appropriate time to create the desired output current from said alternator to an external load circuit, and as the output current passes through zero a self-commutating effect is provided to allow the switch to disconnect the generator from the external circuit

  16. Homogenous and heterogenous advanced oxidation of two commercial reactive dyes.

    Science.gov (United States)

    Balcioglu, I A; Arslan, I; Sacan, M T

    2001-07-01

    Two commercial reactive dyes, the azo dye Reactive Black 5 and the copper phythalocyanine dye Reactive Blue 21, have been treated at a concentration of 75 mg l(-1) by titanium dioxide mediated photocatalytic (TiO2/UV), dark and UV-light assisted Fenton (Fe2+/H2O2) and Fenton-like (Fe3+/H2O2) processes in acidic medium. For the treatment of Reactive Black 5, all investigated advanced oxidation processes were quite effective in terms of colour, COD as well as TOC removal. Moreover, the relative growth inhibition of the azo dye towards the marine algae Dunaliella tertiolecta that was initially 70%, did not exhibit an increase during the studied advanced oxidation reactions and complete detoxification at the end of the treatment period could be achieved for all investigated treatment processes. However, for Reactive Blue 21, abatement in COD and UV-VIS absorbance values was mainly due to the adsorption of the dye on the photocatalyst surface and/or the coagulative effect of Fe3+/Fe2+ ions. Although only a limited fraction of the copper phythalocyanine dye underwent oxidative degradation, 47% of the total copper in the dye was already released after 1 h photocatalytic treatment.

  17. Pulsed neutron sources at KAON

    International Nuclear Information System (INIS)

    Thorson, I.M.; Egelstaff, P.A.; Craddock, M.K.

    1991-01-01

    The proposed KAON Factory facility at TRIUMF consists of a number of synchrotrons and storage rings which offer proton beams of energies between 0.45 and 30 GeV with varying pulse amplitudes, widths and repetition rates. Various possibilities for feeding these beams to a pulsed neutron facility and their potential for future development are examined. The incremental cost of such a pulsed neutron facility is estimated approximately. (author)

  18. Assembly delay line pulse generators

    CERN Multimedia

    CERN PhotoLab

    1971-01-01

    Assembly of six of the ten delay line pulse generators that will power the ten kicker magnet modules. One modulator part contains two pulse generators. Capacitors, inductances, and voltage dividers are in the oil tank on the left. Triggered high-pressure spark gap switches are on the platforms on the right. High voltage pulse cables to the kicker magnet emerge under the spark gaps. In the centre background are the assembled master gaps.

  19. Processing of polymers using reactive solvents

    NARCIS (Netherlands)

    Lemstra, P.J.; Kurja, J.; Meijer, H.E.H.; Meijer, H.E.H.

    1997-01-01

    A review with many refs. on processing of polymers using reactive solvents including classification of synthetic polymers, guidelines for the selection of reactive solvents, basic aspects of processing, examples of intractable and tractable polymer/reactive solvent system

  20. Femtosecond-laser assisted cell reprogramming

    Science.gov (United States)

    Breunig, Hans Georg; Uchugonova, Aisada; Batista, Ana; König, Karsten

    2017-02-01

    Femtosecond-laser pulses can assist to transfect cells by creating transient holes in the cell membrane, thus making them temporarily permeable for extraneous genetic material. This procedure offers the advantage of being completely "virus free" since no viruses are used for the delivery and integration of gene factors into the host genome and, thereby, avoiding serious side effects which so far prevent clinical application. Unfortunately, focusing of the laser radiation onto individual cell membranes is quite elaborate and time consuming. Regarding these obstacles, we briefly review two optical setups for fast, efficient and high throughput laser-assisted cell transfection based on femtosecond laser pulse excitation. The first setup aims at assisting the transfection of adherent cells. It comprises of a modified laser-scanning microscope with beamshaping optics as well as home-made software to automate the detection, targeting and laser-irradiation process. The second setup aims at laser-assisted transfection of non-adherent cells in suspension which move in a continuous flow through the laser focus region. The setup allows to address a large number of cells, however, with much lower transfection efficiency than the individual-cell targeting approach.

  1. Powerful nanosecond pulse train generator

    International Nuclear Information System (INIS)

    Isakov, I.F.; Logachev, E.I.; Opekunov, M.S.; Pechenkin, S.A.; Remnev, G.E.; Usov, Yu.P.

    1987-01-01

    A generator permitting to shape on the load pulsed with the repetition frequency of 10 3 -10 6 Hz and more is described. The amplitude of shaped voltage pulses is up to 150 kV at pulse duration equal to 50 ns. The generator comprises connected in-series with the load two shaping and two transmission lines realized on the base of the KVI-300 low-ohmic cable. The shaping lines are supplied from two independently connected pulse voltage generators for obtaining time interval between pulses > 10 -6 s; they may be also supplied from one generator for obtaining time interval -6 s. At the expense of reducing losses in the discharge circuit the amplitude of the second pulse grows with increase of time interval between pulses up to 300 ns, further on the curve flat-topping exists. The described generator is used in high-current accelerators, in which the primary negative pulse results in generation of explosive-emission plasma, and the second positive pulse provides ion beam shaping including ions of heavy metal used for production of a potential electrode. The generator multipulse mode is used for successive ion acceleration in the transport system

  2. Reactive Collision Avoidance Algorithm

    Science.gov (United States)

    Scharf, Daniel; Acikmese, Behcet; Ploen, Scott; Hadaegh, Fred

    2010-01-01

    The reactive collision avoidance (RCA) algorithm allows a spacecraft to find a fuel-optimal trajectory for avoiding an arbitrary number of colliding spacecraft in real time while accounting for acceleration limits. In addition to spacecraft, the technology can be used for vehicles that can accelerate in any direction, such as helicopters and submersibles. In contrast to existing, passive algorithms that simultaneously design trajectories for a cluster of vehicles working to achieve a common goal, RCA is implemented onboard spacecraft only when an imminent collision is detected, and then plans a collision avoidance maneuver for only that host vehicle, thus preventing a collision in an off-nominal situation for which passive algorithms cannot. An example scenario for such a situation might be when a spacecraft in the cluster is approaching another one, but enters safe mode and begins to drift. Functionally, the RCA detects colliding spacecraft, plans an evasion trajectory by solving the Evasion Trajectory Problem (ETP), and then recovers after the collision is avoided. A direct optimization approach was used to develop the algorithm so it can run in real time. In this innovation, a parameterized class of avoidance trajectories is specified, and then the optimal trajectory is found by searching over the parameters. The class of trajectories is selected as bang-off-bang as motivated by optimal control theory. That is, an avoiding spacecraft first applies full acceleration in a constant direction, then coasts, and finally applies full acceleration to stop. The parameter optimization problem can be solved offline and stored as a look-up table of values. Using a look-up table allows the algorithm to run in real time. Given a colliding spacecraft, the properties of the collision geometry serve as indices of the look-up table that gives the optimal trajectory. For multiple colliding spacecraft, the set of trajectories that avoid all spacecraft is rapidly searched on

  3. Mannuronic Acids : Reactivity and Selectivity

    NARCIS (Netherlands)

    Codee, Jeroen D. C.; Walvoort, Marthe T. C.; de Jong, Ana-Rae; Lodder, Gerrit; Overkleeft, Herman S.; van der Marel, Gijsbert A.

    2011-01-01

    This review describes our recent studies toward the reactivity and selectivity of mannopyranosyl uronic acid donors, which have been found to be very powerful donors for the construction of beta-mannosidic linkages.

  4. Fuel Temperature Coefficient of Reactivity

    Energy Technology Data Exchange (ETDEWEB)

    Loewe, W.E.

    2001-07-31

    A method for measuring the fuel temperature coefficient of reactivity in a heterogeneous nuclear reactor is presented. The method, which is used during normal operation, requires that calibrated control rods be oscillated in a special way at a high reactor power level. The value of the fuel temperature coefficient of reactivity is found from the measured flux responses to these oscillations. Application of the method in a Savannah River reactor charged with natural uranium is discussed.

  5. [Hyper-reactive malarial splenomegaly].

    Science.gov (United States)

    Maazoun, F; Deschamps, O; Barros-Kogel, E; Ngwem, E; Fauchet, N; Buffet, P; Froissart, A

    2015-11-01

    Hyper-reactive malarial splenomegaly is a rare and severe form of chronic malaria. This condition is a common cause of splenomegaly in endemic areas. The pathophysiology of hyper-reactive malarial splenomegaly involves an intense immune reaction (predominantly B cell-driven) to repeated/chronic infections with Plasmodium sp. The diagnosis may be difficult, due to a poorly specific clinical presentation (splenomegaly, fatigue, cytopenias), a long delay between residence in a malaria-endemic area and onset of symptoms, and a frequent absence of parasites on conventional thin and thick blood smears. A strongly contributive laboratory parameter is the presence of high levels of total immunoglobulin M. When the diagnostic of hyper-reactive malarial splenomegaly is considered, search for anti-Plasmodium antibodies and Plasmodium nucleic acids (genus and species) by PCR is useful. Diagnosis of hyper-reactive malarial splenomegaly relies on the simultaneous presence of epidemiological, clinical, biological and follow-up findings. Regression of both splenomegaly and hypersplenism following antimalarial therapy allows the differential diagnosis with splenic lymphoma, a common complication of hyper-reactive malarial splenomegaly. Although rare in Western countries, hyper-reactive malarial splenomegaly deserves increased medical awareness to reduce the incidence of incorrect diagnosis, to prevent progression to splenic lymphoma and to avoid splenectomy. Copyright © 2015 Société nationale française de médecine interne (SNFMI). Published by Elsevier SAS. All rights reserved.

  6. Model study of an automatic controller of the IBR-2 pulsed reactor

    International Nuclear Information System (INIS)

    Pepelyshev, Yu.N.; Popov, A.K.

    2007-01-01

    For calculation of power transients in the IBR-2 reactor a special mathematical model of dynamics taking into account the discontinuous jump of reactivity by an automatic controller with the step motor is created. In the model the nonlinear dependence of the energy of power pulse on the reactivity and the influence of warming up of the reactor on the reactivity by means of introduction of a nonlinear feedback 'power-pulse energy - reactivity' are taken into account. With the help of the model the transients of relative deviation of power-pulse energy are calculated at various (random, mixed and regular) reactivity disturbances at the reactor mean power 1.475 MW. It is shown that to improve the quality of processes the choice of such regular values of parameters of the automatic controller is expedient, at which the least effect of smoothing of a signal acting on an automatic controller and the least speed of an automatic controller are provided, and the reduction of efficiency of one step of the automatic controller and introduction of a five-percent dead space are also expedient

  7. New MR pulse sequence

    International Nuclear Information System (INIS)

    Harms, S.E.; Flamig, D.P.; Griffey, R.H.

    1990-01-01

    This paper describes a method for fat suppression for three-dimensional MR imaging. The FATS (fat-suppressed acquisition with echo time shortened) sequence employs a pair of opposing adiabatic half-passage RF pulses tuned on fat resonance. The imaging parameters are as follows: TR, 20 msec; TE, 21.7-3.2 msec; 1,024 x 128 x 128 acquired matrix; imaging time, approximately 11 minutes. A series of 54 examinations were performed. Excellent fat suppression with water excitation is achieved in all cases. The orbital images demonstrate superior resolution of small orbital lesions. The high signal-to-noise ratio (SNR) in cranial studies demonstrates excellent petrous bone and internal auditory canal anatomy

  8. Digital pulse shape discrimination

    International Nuclear Information System (INIS)

    Miller, L. F.; Preston, J.; Pozzi, S.; Flaska, M.; Neal, J.

    2007-01-01

    Pulse-shape discrimination (PSD) has been utilised for about 40 years as a method to obtain estimates for dose in mixed neutron and photon fields. Digitizers that operate close to GHz are currently available at a reasonable cost, and they can be used to directly sample signals from photomultiplier tubes. This permits one to perform digital PSD rather than the traditional, and well-established, analogous techniques. One issue that complicates PSD for neutrons in mixed fields is that the light output characteristics of typical scintillators available for PSD, such as BC501A, vary as a function of energy deposited in the detector. This behaviour is more easily accommodated with digital processing of signals than with analogous signal processing. Results illustrate the effectiveness of digital PSD. (authors)

  9. Pulsed Compression Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Roestenberg, T. [University of Twente, Enschede (Netherlands)

    2012-06-07

    The advantages of the Pulsed Compression Reactor (PCR) over the internal combustion engine-type chemical reactors are briefly discussed. Over the last four years a project concerning the fundamentals of the PCR technology has been performed by the University of Twente, Enschede, Netherlands. In order to assess the feasibility of the application of the PCR principle for the conversion methane to syngas, several fundamental questions needed to be answered. Two important questions that relate to the applicability of the PCR for any process are: how large is the heat transfer rate from a rapidly compressed and expanded volume of gas, and how does this heat transfer rate compare to energy contained in the compressed gas? And: can stable operation with a completely free piston as it is intended with the PCR be achieved?.

  10. Pulse-shaping strategies in short-pulse fiber amplifiers

    Energy Technology Data Exchange (ETDEWEB)

    Schimpf, Damian Nikolaus

    2010-02-09

    Ultrashort pulse lasers are an important tool in scientific and industrial applications. However, many applications are demanding higher average powers from these ultrashort pulse sources. This can be achieved by combining direct diode pumping with novel gain media designs. In particular, ultrashort pulse fiber lasers are now delivering average powers in the kW range. However, the design of fiber lasers, producing pulses with high peak-powers, is challenging due to the impact of nonlinear effects. To significantly reduce these detrimental effects in ultrashort pulse fiber amplifers, the combination of chirped pulse amplification (CPA) and large mode area fibers is employed. Using these methods, the pulse energy of fiber lasers has been steadily increasing for the past few years. Recently, a fiber-based CPA-system has been demonstrated which produces pulse energies of around 1 mJ. However, both the stretching and the enlargement of the mode area are limited, and therefore, the impact of nonlinearity is still noticed in systems employing such devices. The aim of this thesis is the analysis of CPA-systems operated beyond the conventional nonlinear limit, which corresponds to accumulated nonlinear phase-shifts around 1 rad. This includes a detailed discussion of the influence of the nonlinear effect self-phase modulation on the output pulse of CPA-systems. An analytical model is presented. Emphasis is placed on the design of novel concepts to control the impact of self-phase modulation. Pulse-shaping is regarded as a powerful tool to accomplish this goal. Novel methods to control the impact of SPM are experimentally demonstrated. The design of these concepts is based on the theoretical findings. Both amplitude- and phase-shaping are studied. Model-based phase-shaping is implemented in a state-of-the-art fiber CPA-system. The influence of the polarization state is also highlighted. Additionally, existing techniques and recent advances are put into context. (orig.)

  11. Pulse-shaping strategies in short-pulse fiber amplifiers

    International Nuclear Information System (INIS)

    Schimpf, Damian Nikolaus

    2010-01-01

    Ultrashort pulse lasers are an important tool in scientific and industrial applications. However, many applications are demanding higher average powers from these ultrashort pulse sources. This can be achieved by combining direct diode pumping with novel gain media designs. In particular, ultrashort pulse fiber lasers are now delivering average powers in the kW range. However, the design of fiber lasers, producing pulses with high peak-powers, is challenging due to the impact of nonlinear effects. To significantly reduce these detrimental effects in ultrashort pulse fiber amplifers, the combination of chirped pulse amplification (CPA) and large mode area fibers is employed. Using these methods, the pulse energy of fiber lasers has been steadily increasing for the past few years. Recently, a fiber-based CPA-system has been demonstrated which produces pulse energies of around 1 mJ. However, both the stretching and the enlargement of the mode area are limited, and therefore, the impact of nonlinearity is still noticed in systems employing such devices. The aim of this thesis is the analysis of CPA-systems operated beyond the conventional nonlinear limit, which corresponds to accumulated nonlinear phase-shifts around 1 rad. This includes a detailed discussion of the influence of the nonlinear effect self-phase modulation on the output pulse of CPA-systems. An analytical model is presented. Emphasis is placed on the design of novel concepts to control the impact of self-phase modulation. Pulse-shaping is regarded as a powerful tool to accomplish this goal. Novel methods to control the impact of SPM are experimentally demonstrated. The design of these concepts is based on the theoretical findings. Both amplitude- and phase-shaping are studied. Model-based phase-shaping is implemented in a state-of-the-art fiber CPA-system. The influence of the polarization state is also highlighted. Additionally, existing techniques and recent advances are put into context. (orig.)

  12. Role of Antioxidants in Assisted Reproductive Techniques

    Directory of Open Access Journals (Sweden)

    Ashok Agarwal

    2017-08-01

    Full Text Available Oxidative stress (OS has been recognized as a significant cause of suboptimal assisted reproductive outcome. Many of the sperm preparation and manipulation procedures that are necessary in the in vitro environment can result in excessive production of reactive oxygen species (ROS thereby exposing the gametes and growing embryos to significant oxidative damage. Antioxidants have long been utilized in the management of male subfertility as they can counterbalance the elevated levels of ROS inducing a high state of OS. Few studies have looked into the clinical effectiveness of antioxidants in patients undergoing assisted reproduction. While an overall favorable outcome has been perceived, the specific clinical indication and optimal antioxidant regimen remain unknown. The goal of our review is to explore the sources of ROS in the in vitro environment and provide a clinical scenario-based approach to identify the circumstances where antioxidant supplementation is most beneficial to enhance the outcome of assisted reproduction.

  13. Bringing Pulsed Laser Welding into Production

    DEFF Research Database (Denmark)

    Olsen, Flemmming Ove

    1996-01-01

    In this paper, some research and develop-ment activities within pulsed laser welding technology at the Tech-nical University of Denmark will be described. The laser group at the Insti-tute for Manufacturing Technology has nearly 20 years of experience in laser materials process-ing. Inter......-nationally the group is mostly known for its contri-butions to the development of the laser cutting process, but further it has been active within laser welding, both in assisting industry in bringing laser welding into production in several cases and in performing fundamental R & D. In this paper some research...... activities concerning the weldability of high alloyed austenitic stainless steels for mass production industry applying industrial lasers for fine welding will be described. Studies on hot cracking sensitivity of high alloyed austenitic stainless steel applying both ND-YAG-lasers and CO2-lasers has been...

  14. Crack imaging by pulsed laser spot thermography

    International Nuclear Information System (INIS)

    Li, T; Almond, D P; Rees, D A S; Weekes, B

    2010-01-01

    A surface crack close to a spot heated by a laser beam impedes lateral heat flow and produces alterations to the shape of the thermal image of the spot that can be monitored by thermography. A full 3D simulation has been developed to simulate heat flow from a laser heated spot in the proximity of a crack. The modelling provided an understanding of the ways that different parameters affect the thermal images of laser heated spots. It also assisted in the development of an efficient image processing strategy for extracting the scanned cracks. Experimental results show that scanning pulsed laser spot thermography has considerable potential as a remote, non-contact crack imaging technique.

  15. Formation of novel reactive intermediate by electron-laser dual beam irradiation

    International Nuclear Information System (INIS)

    Ishida, Akito; Takamuku, Setsuo

    1992-01-01

    The pulse radiolysis system of the Institute of Scientific and Industrial Research, Osaka University, (ISIR) has been progressed to observe a highly reactive species, which is produced by successive irradiation of electron and laser or of CW-UV-light and electron. The dual beam irradiation system, which consists of the beam synchronization system, the optical alignment, and the measurement system, is described in detail. Dual beam irradiation studies on 2-methylbenzophenone and some compounds with a C=N bond have been carried out by use of this system. Pulse radiolysis of 2-methylbenzophenone in benzene induced formation of an unstable photoenol via the triplet state, which was irradiated by a visible laser pulse to give dihydroanthrone. Pulse radiolysis of syn-benzalaniline and a nitrileylide in 2-methyltetrahydrofuran, which were produced by steady state photoirradiation at low temperature, enabled us to observe their very unstable radical anions. (author)

  16. Reactive sites influence in PMMA oligomers reactivity: a DFT study

    Science.gov (United States)

    Paz, C. V.; Vásquez, S. R.; Flores, N.; García, L.; Rico, J. L.

    2018-01-01

    In this work, we present a theoretical study of methyl methacrylate (MMA) living anionic polymerization. The study was addressed to understanding two important experimental observations made for Michael Szwarc in 1956. The unexpected effect of reactive sites concentration in the propagation rate, and the self-killer behavior of MMA (deactivating of living anionic polymerization). The theoretical calculations were performed by density functional theory (DFT) to obtain the frontier molecular orbitals values. These values were used to calculate and analyze the chemical interaction descriptors in DFT-Koopmans’ theorem. As a result, it was observed that the longest chain-length species (related with low concentration of reactive sites) exhibit the highest reactivity (behavior associated with the increase of the propagation rate). The improvement in this reactivity was attributed to the crosslinking produced in the polymethyl methacrylate chains. Meanwhile, the self-killer behavior was associated with the intermolecular forces present in the reactive sites. This behavior was associated to an obstruction in solvation, since the active sites remained active through all propagation species. The theoretical results were in good agreement with the Szwarc experiments.

  17. The Vulcan pulse generating system

    International Nuclear Information System (INIS)

    Danson, C.N.; Edwards, C.B.; Wyatt, R.W.W.

    1985-01-01

    During the past two years several changes have been made to the front end system on the VULCAN pulse generating system. These changes give greater flexibility and a wider choice of operating conditions. This note gives an updated description of the system capabilities, and gives users of the facility an idea of the various pulse combinations that are available. (author)

  18. NMR in pulsed magnetic field

    KAUST Repository

    Abou-Hamad, Edy; Bontemps, P.; Rikken, Geert L J A

    2011-01-01

    Nuclear magnetic resonance (NMR) experiments in pulsed magnetic fields up to 30.4 T focused on 1H and 93Nb nuclei are reported. Here we discuss the advantage and limitation of pulsed field NMR and why this technique is able to become a promising research tool. © 2011 Elsevier Inc. All Rights Reserved.

  19. Progress in pulsed power fusion

    Energy Technology Data Exchange (ETDEWEB)

    Quintenz, J P; Adams, R G; Bailey, J E [Sandia Labs., Albuquerque, NM (United States); and others

    1997-12-31

    Pulsed power offers an efficient, high energy, economical source of x-rays for inertial confinement fusion (ICF) research. Two main approaches to ICF driven with pulsed power accelerators are pursued: intense light ion beams and z-pinches. Recent progress in each approach and plans for future development is described. (author). 2 figs., 10 refs.

  20. NMR in pulsed magnetic field

    KAUST Repository

    Abou-Hamad, Edy

    2011-09-01

    Nuclear magnetic resonance (NMR) experiments in pulsed magnetic fields up to 30.4 T focused on 1H and 93Nb nuclei are reported. Here we discuss the advantage and limitation of pulsed field NMR and why this technique is able to become a promising research tool. © 2011 Elsevier Inc. All Rights Reserved.

  1. A Single-Pulse Integrator

    DEFF Research Database (Denmark)

    Miller, Arne

    1974-01-01

    A single-pulse integrator is described. It gives a relative measure of the integral of the output signal from a coil monitor on the Risø 10 MeV linear accelerator, and displays the value on a digital voltmeter. The reproduccibility is found to be better than ±1% for an accelerated pulse charge...

  2. Progress in pulsed power fusion

    International Nuclear Information System (INIS)

    Quintenz, J.P.; Adams, R.G.; Bailey, J.E.

    1996-01-01

    Pulsed power offers an efficient, high energy, economical source of x-rays for inertial confinement fusion (ICF) research. Two main approaches to ICF driven with pulsed power accelerators are pursued: intense light ion beams and z-pinches. Recent progress in each approach and plans for future development is described. (author). 2 figs., 10 refs

  3. Impact of pulse duration on Ho:YAG laser lithotripsy: fragmentation and dusting performance.

    Science.gov (United States)

    Bader, Markus J; Pongratz, Thomas; Khoder, Wael; Stief, Christian G; Herrmann, Thomas; Nagele, Udo; Sroka, Ronald

    2015-04-01

    In vitro investigations of Ho:YAG laser-induced stone fragmentation were performed to identify potential impacts of different pulse durations on stone fragmentation characteristics. A Ho:YAG laser system (Swiss LaserClast, EMS S.A., Nyon, Switzerland) with selectable long or short pulse mode was tested with regard to its fragmentation and laser hardware compatibility properties. The pulse duration is depending on the specific laser parameters. Fragmentation tests (hand-held, hands-free, single-pulse-induced crater) on artificial BEGO stones were performed under reproducible experimental conditions (fibre sizes: 365 and 200 µm; laser settings: 10 W through combinations of 0.5, 1, 2 J/pulse and 20, 10, 5 Hz, respectively). Differences in fragmentation rates between the two pulse duration regimes were detected with statistical significance for defined settings. Hand-held and motivated Ho:YAG laser-assisted fragmentation of BEGO stones showed no significant difference between short pulse mode and long pulse mode, neither in fragmentation rates nor in number of fragments and fragment sizes. Similarly, the results of the hands-free fragmentation tests (with and without anti-repulsion device) showed no statistical differences between long pulse and short pulse modes. The study showed that fragmentation rates for long and short pulse durations at identical power settings remain at a comparable level. Longer holmium laser pulse duration reduces stone pushback. Therefore, longer laser pulses may result in better clinical outcome of laser lithotripsy and more convenient handling during clinical use without compromising fragmentation effectiveness.

  4. Electromagnetic pulses, localized and causal

    Science.gov (United States)

    Lekner, John

    2018-01-01

    We show that pulse solutions of the wave equation can be expressed as time Fourier superpositions of scalar monochromatic beam wave functions (solutions of the Helmholtz equation). This formulation is shown to be equivalent to Bateman's integral expression for solutions of the wave equation, for axially symmetric solutions. A closed-form one-parameter solution of the wave equation, containing no backward-propagating parts, is constructed from a beam which is the tight-focus limit of two families of beams. Application is made to transverse electric and transverse magnetic pulses, with evaluation of the energy, momentum and angular momentum for a pulse based on the general localized and causal form. Such pulses can be represented as superpositions of photons. Explicit total energy and total momentum values are given for the one-parameter closed-form pulse.

  5. A digital long pulse integrator

    International Nuclear Information System (INIS)

    Broesch, J.D.; Strait, E.J.; Snider, R.T.

    1996-10-01

    A prototype digital integrator with very long integration capabilities has been developed and field tested on an inductive magnetic sensor on the DIII-D Tokamak. The integrator is being developed for use on ITER with a pulse length of 1000 s, and has direct applications for other long pulse Tokamaks. Inductive magnetic sensors are routinely used on existing Tokamaks, are well understood, and are extremely robust, however, they require integration of the signal to determine the magnetic field strength. The next generation of Tokamaks, will have pulse lengths of 1000 s or longer, require integrators with drift and noise characteristics compatible with the very long pulse lengths. This paper will discuss the architecture, algorithms, and programming of the Long Pulse Integrator (LPI). Of particular interest are the noise control and the built-in offset correction techniques used in this application

  6. Transport of reactive and nonreactive solutes

    International Nuclear Information System (INIS)

    Garabedian, S.P.; Leblanc, D.R.

    1990-01-01

    A natural-gradient tracer test was conducted on Cape Cod, Massachusetts, to examine the transport and dispersion of solutes in a sand and gravel aquifer. A nonreactive tracer, bromide, and two reactive tracers, lithium and molybdate, were injected as a pulse in July 1985 and monitored in three dimensions for 3 years as they moved 280 meters downgradient through an array of multilevel samplers. The tracer transport was quantified using spatial moments. The calculated total mass of bromide for each sampling date varied from 86 to 105 percent of the injected mass, and the center of mass moved at a nearly constant horizontal velocity of 0.42 meters per day. The bromide cloud also moved downward about 4 meters, probably because of density-induced sinking and accretion of areal recharge from precipitation. After 200 meters of transport, the bromide cloud was more than 80 meters long but only 14 meters wide and 6 meters thick. The change in longitudinal dispersivity had reached a constant value (0.96 meters). The transverse horizontal and transverse vertical dispersivities were much smaller (1.8 centimeters and 1.5 millimeters, respectively) than the longitudinal value. The lithium and molybdate clouds followed the same path as the bromide cloud, but a significant amount of their mass was adsorbed onto the aquifer sediments, and their rates of movement were retarded about 50 percent relative to the bromide movement. (Author) (5 figs., 23 refs.)

  7. Reactive Strength Index: A Poor Indicator of Reactive Strength?

    Science.gov (United States)

    Healy, Robin; Kenny, Ian; Harrison, Drew

    2017-11-28

    The primary aim was to assess the relationships between reactive strength measures and associated kinematic and kinetic performance variables achieved during drop jumps. A secondary aim was to highlight issues with the use of reactive strength measures as performance indicators. Twenty eight national and international level sprinters, consisting of fourteen men and women, participated in this cross-sectional analysis. Athletes performed drop jumps from a 0.3 m box onto a force platform with dependent variables contact time (CT), landing time (TLand), push-off time (TPush), flight time (FT), jump height (JH), reactive strength index (RSI, calculated as JH / CT), reactive strength ratio (RSR, calculated as FT / CT) and vertical leg spring stiffness (Kvert) recorded. Pearson's correlation test found very high to near perfect relationships between RSI and RSR (r = 0.91 to 0.97), with mixed relationships found between RSI, RSR and the key performance variables, (Men: r = -0.86 to -0.71 between RSI/RSR and CT, r = 0.80 to 0.92 between RSI/RSR and JH; Women: r = -0.85 to -0.56 between RSR and CT, r = 0.71 between RSI and JH). This study demonstrates that the method of assessing reactive strength (RSI versus RSR) may be influenced by the performance strategies adopted i.e. whether an athlete achieves their best reactive strength scores via low CTs, high JHs or a combination. Coaches are advised to limit the variability in performance strategies by implementing upper and / or lower CT thresholds to accurately compare performances between individuals.

  8. Pulsed neutron generator for use with pulsed neutron activation techniques

    International Nuclear Information System (INIS)

    Rochau, G.E.

    1980-01-01

    A high-output, transportable, pulsed neutron generator has been developed by Sandia National Laboratories for use with Pulsed Neutron Activation (PNA) techniques. The PNA neutron generator generates > 10 10 14 MeV D-T neutrons in a 1.2 millisecond pulse. Each operation of the unit will produce a nominal total neutron output of 1.2 x 10 10 neutrons. The generator has been designed to be easily repaired and modified. The unit requires no additional equipment for operation or measurement of output

  9. Laser ablation comparison by picosecond pulses train and nanosecond pulse

    Science.gov (United States)

    Lednev, V. N.; Filippov, M. N.; Bunkin, A. F.; Pershin, S. M.

    2015-12-01

    A comparison of laser ablation by a train of picosecond pulses and nanosecond pulses revealed a difference in laser craters, ablation thresholds, plasma sizes and spectral line intensities. Laser ablation with a train of picosecond pulses resulted in improved crater quality while ablated mass decreased up to 30%. A reduction in laser plasma dimensions for picosecond train ablation was observed while the intensity of atomic/ionic lines in the plasma spectra was greater by a factor of 2-4 indicating an improved excitation and atomization in the plasma.

  10. Effect of pulse current on acidification and removal of Cu, Cd, and As during suspended electrodialytic soil remediation

    DEFF Research Database (Denmark)

    Sun, Tian Ran; Ottosen, Lisbeth M.; Jensen, Pernille Erland

    2013-01-01

    The effect of pulse current on the acidification process and the removal of heavy metals during suspended electrodialytic soil remediation were investigated in this work. Eight experiments with constant and pulse current in two polluted soils were conducted using a 3-compartment membrane cell......, predominately working under overlimiting current density conditions. Soil 1 was sampled from a pile of excavated soil at a site with mixed industrial pollution (Cu and Cd), and soil 2 was sampled from the top layer of a wood preservation site (Cu and As). Results showed that pulse current improved...... the acidification by supplying more reactive H+ ions (defined as the H+ ions causing release of heavy metals from soil particles). The molar ratio of reactive H+ ions to total produced H+ ions (RH+/PH+) was higher in every pulse current experiment than in the corresponding constant current experiment. In addition...

  11. Pulse on pulse: modulation and signification in Rafael Lozano-Hemmer's Pulse Room

    Directory of Open Access Journals (Sweden)

    Merete Carlson

    2012-06-01

    Full Text Available This article investigates the relation between signifying processes and non-signifying material dynamism in the installation Pulse Room (2006 by Mexican Canadian artist Rafael Lozano-Hemmer. In Pulse Room the sense of pulse is ambiguous. Biorhythms are transmitted from the pulsing energy of the visitor's beating heart to the flashing of a fragile light bulb, thereby transforming each light bulb into a register of individual life. But at the same time the flashing light bulbs together produce a chaotically flickering light environment composed by various layers of repetitive rhythms, a vibrant and pulsating “room”. Hence, the visitor in Pulse Room is invited into a complex scenario that continuously oscillates between various aspects of signification (the light bulbs representing individual lives; the pulse itself as the symbolic “rhythm of life” and instants of pure material processuality (flickering light bulbs; polyrhythmic layers. Taking our point of departure in a discussion of Gilles Deleuze's concepts of modulation and signaletic material in relation to electronic media, we examine how the complex orchestration of pulsation between signification and material modulation produces a multilayered sense of time and space that is central to the sensory experience of Pulse Room as a whole. Pulse Room is, at the very same time, a relational subject–object intimacy and an all-encompassing immersive environment modulating continuously in real space-time.

  12. Biodecolorization and biodegradation of Reactive Blue by ...

    African Journals Online (AJOL)

    SERVER

    2007-06-18

    Jun 18, 2007 ... Aspergillus sp. effectively decolorized Reactive Blue and other structurally different synthetic dyes. Agitation was found to be an important ... Few chemically different dyes such as Reactive Black (75%), Reactive Yellow (70%),. Reactive Red (33%) and ..... Degradation of azo dyes by the lignin degrading ...

  13. Substation Reactive Power Regulation Strategy

    Science.gov (United States)

    Zhang, Junfeng; Zhang, Chunwang; Ma, Daqing

    2018-01-01

    With the increasing requirements on the power supply quality and reliability of distribution network, voltage and reactive power regulation of substations has become one of the indispensable ways to ensure voltage quality and reactive power balance and to improve the economy and reliability of distribution network. Therefore, it is a general concern of the current power workers and operators that what kind of flexible and effective control method should be used to adjust the on-load tap-changer (OLTC) transformer and shunt compensation capacitor in a substation to achieve reactive power balance in situ, improve voltage pass rate, increase power factor and reduce active power loss. In this paper, based on the traditional nine-zone diagram and combining with the characteristics of substation, a fuzzy variable-center nine-zone diagram control method is proposed and used to make a comprehensive regulation of substation voltage and reactive power. Through the calculation and simulation of the example, this method is proved to have satisfactorily reconciled the contradiction between reactive power and voltage in real-time control and achieved the basic goal of real-time control of the substation, providing a reference value to the practical application of the substation real-time control method.

  14. Pulse shaping using a spatial light modulator

    CSIR Research Space (South Africa)

    Botha, N

    2009-07-01

    Full Text Available Femtosecond pulse shaping can be done by different kinds of pulse shapers, such as liquid crystal spatial light modulators (LC SLM), acousto optic modulators (AOM) and deformable and movable mirrors. A few applications where pulse shaping...

  15. Enterprise Deployment Through PulseRider To Treat Anterior Communicating Artery Aneurysm Recurrence.

    Science.gov (United States)

    Valente, Iacopo; Limbucci, Nicola; Nappini, Sergio; Rosi, Andrea; Laiso, Antonio; Mangiafico, Salvatore

    2018-02-01

    PulseRider (Pulsar Vascular, Los Gatos, California, USA) is a new endovascular device designed to treat wide-neck bifurcation intracranial aneurysms. Deployment of a stent through a PulseRider to treat an aneurysm's recurrence has never been described before. We report the case of a 55-year-old man who underwent coiling of an 8-mm anterior communicating artery aneurysm with assistance of a PulseRider neck reconstruction device. The 6-month digital subtraction angiography control showed aneurysm recurrence, so we deployed an Enterprise 2 closed-cell stent (Codman, Miami Lakes, Florida, USA) in the A1-A2 segment passing across the previously implanted PulseRider. Enterprise correctly expanded and allowed for adequate coiling of the aneurysm. An Enterprise stent can be safely opened through a PulseRider in order to treat aneurysm recurrence. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. AIREK-PUL, Periodic Kinetics Problems of Pulsed Reactors

    International Nuclear Information System (INIS)

    Inzaghi, A.; Misenta, R.

    1984-01-01

    1 - Nature of physical problem solved: Solves periodic problems about the kinetics of pulsed reactors or problems where the reactivity has rapid variations. The program uses two constant steps for the integration of the system of differential equations, the first step during the first half-period and the second step during the second half-period. Available for either single or double precision. 2 - Method of solution: The differential equations are integrated using the fourth-order Runge-Kutta method as modified by E.R. Cohen (Geneva Conference, 1958). 3 - Restrictions on the complexity of the problem: The maximum number of differential equations that can be solved simultaneously is 50

  17. One-electron oxidations of ferrocenes: a pulse radiolysis study

    International Nuclear Information System (INIS)

    Faraggi, Moshe; Weinraub, Dany; Broitman, Federico; DeFelippis, M.R.; Klapper, M.H.

    1988-01-01

    Using the pulse radiolysis technique we have studied the oxidation by various inorganic radicals of four water soluble ferrocene derivatives, hydroxyethyl, dimethylaminomethyl, monocarboxylic acid and dicarboxylic acid. We report the second order rate constants for these reactions, the stabilities and spectral properties of the ferrocinium products, and the electrochemically determined ferrocinium/ferrocene redox potentials. We also present preliminary estimates of tyrosine and tryptophan radical redox potentials obtained with the dicarboxylic acid ferrocene derivative as reference, and we discuss the relationship between redox potential differences and the reactivities of the ferrocenes with the inorganic radicals. (author)

  18. The reactivity of natural phenols

    Energy Technology Data Exchange (ETDEWEB)

    Denisov, Evgenii T; Denisova, Taisa G [Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region (Russian Federation)

    2009-11-30

    This review surveys physicochemical data of natural phenols published in recent years. The structures of some compounds of this class are given. A complete set of the dissociation energies of the O-H bonds for 71 natural phenols is presented. Kinetic characteristics of the reactions of peroxyl, alkyl and thiyl radicals with natural phenols, exchange reactions of phenoxyl radicals with phenols and reactions of phenoxyl radicals with lipids, hydroperoxides, cysteine and ascorbic acid are compiled and described systematically. The reactivity of phenols in radical reactions and the factors that determine the reactivity (the enthalpy of reaction, triplet repulsion, the electronegativities of atoms at the reaction centre, the presence of pi-electrons adjacent to the reaction centre, the radii of atoms at the reaction centre, steric hindrance, the force constants of the reacting bonds) are discussed. An important role of hydrogen bonding between surrounding molecules and the OH groups of natural phenols in decreasing their reactivities is noted.

  19. Bomb pulse biology

    Energy Technology Data Exchange (ETDEWEB)

    Falso, Miranda J. Sarachine [Center for Accelerator Mass Spectrometry, Mail Stop L-397, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94551 (United States); Buchholz, Bruce A., E-mail: buchholz2@llnl.gov [Center for Accelerator Mass Spectrometry, Mail Stop L-397, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94551 (United States)

    2013-01-15

    The past decade has seen an explosion in use of the {sup 14}C bomb pulse to do fundamental cell biology. Studies in the 1960s used decay counting to measure tissue turnover when the atmospheric {sup 14}C/C concentration was changing rapidly. Today bulk tissue measurements are of marginal interest since most of the carbon in the tissue resides in proteins, lipids and carbohydrates that turn over rapidly. Specific cell types with specialized functions are the focus of cell turnover investigations. Tissue samples need to be fresh or frozen. Fixed or preserved samples contain petroleum-derived carbon that has not been successfully removed. Cell or nuclear surface markers are used to sort specific cell types, typically by fluorescence-activated cell sorting (FACS). Specific biomolecules need to be isolated with high purity and accelerator mass spectrometry (AMS) measurements must accommodate samples that generally contain less than 40 {mu}g of carbon. Furthermore, all separations must not add carbon to the sample. Independent means such as UV absorbance must be used to confirm molecule purity. Approaches for separating specific proteins and DNA and combating contamination of undesired molecules are described.

  20. Pulsed radiation decay logging

    International Nuclear Information System (INIS)

    Mills, W.R. Jr.

    1983-01-01

    There are provided new and improved well logging processes and systems wherein the detection of secondary radiation is accomplished during a plurality of time windows in a manner to accurately characterize the decay rate of the secondary radiation. The system comprises a well logging tool having a primary pulsed radiation source which emits repetitive time-spaced bursts of primary radiation and detector means for detecting secondary radiation resulting from the primary radiation and producing output signals in response to the detected radiation. A plurality of measuring channels are provided, each of which produces a count rate function representative of signals received from the detector means during successive time windows occurring between the primary radiation bursts. The logging system further comprises means responsive to the measuring channels for producing a plurality of functions representative of the ratios of the radiation count rates measured during adjacent pairs of the time windows. Comparator means function to compare the ratio functions and select at least one of the ratio functions to generate a signal representative of the decay rate of the secondary radiation

  1. NEMP (Nuclear Electromagnetic Pulse)

    International Nuclear Information System (INIS)

    Grunow, H.K.

    The variety of measures discussed in this contribution can be used to achieve with minimum effort a damping of 10 6 :1 (120 dB) between the interfering pulses in the networks and lines outside the buildings and the lines leading to the semiconductors. Expert knowledge, experience, and insight into the systems are required to solve this task optimally. The procedure to be adopted for NEMP protection differs only slightly from that used for achieving electromagnetic compatibility and lightning protection. Industry has developed the equipment for overvoltage protection and offers graded protection systems, experienced experts and systems engineers are available. This potential of the industry could be used to sponsor a pilot project, e.g. by public research funds. One of the goals of such a project could be to work out reliable data for cost estimated for large projects. Even if one would not accept the hypothetical probability of a nuclear war as a reason good anough to start such a project, it would not be justified to deny the necessity of additional expenditure for setting up a ''NEMP emergency system'' for protection waterborne traffic on purely financial grounds. (orig./RW) [de

  2. Institutionalizing Security Force Assistance

    National Research Council Canada - National Science Library

    Binetti, Michael R

    2008-01-01

    .... It looks at the manner in which security assistance guidance is developed and executed. An examination of national level policy and the guidance from senior military and civilian leaders highlights the important role of Security Force Assistance...

  3. ForeignAssistance.gov

    Data.gov (United States)

    US Agency for International Development — ForeignAssistance.gov provides a view of U.S. Government foreign assistance funds across agencies and enables users to explore, analyze, and review aid investments...

  4. Partnership for Prescription Assistance

    Science.gov (United States)

    ... may use our name without our permission. The Partnership for Prescription Assistance will help you find the ... Events Blog Facebook Twitter Start living better. The Partnership for Prescription Assistance helps qualifying patients without prescription ...

  5. Assisted delivery with forceps

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/patientinstructions/000509.htm Assisted delivery with forceps To use the sharing features on ... called vacuum assisted delivery . When is a Forceps Delivery Needed? Even after your cervix is fully dilated ( ...

  6. Vacuum-assisted delivery

    Science.gov (United States)

    ... medlineplus.gov/ency/patientinstructions/000514.htm Vacuum-assisted delivery To use the sharing features on this page, ... through the birth canal. When is Vacuum-assisted Delivery Needed? Even after your cervix is fully dilated ( ...

  7. Magnetic Alignment of Pulsed Solenoids Using the Pulsed Wire Method

    International Nuclear Information System (INIS)

    Arbelaez, D.; Madur, A.; Lipton, T.M.; Waldron, W.L.; Kwan, J.W.

    2011-01-01

    A unique application of the pulsed-wire measurement method has been implemented for alignment of 2.5 T pulsed solenoid magnets. The magnetic axis measurement has been shown to have a resolution of better than 25 (micro)m. The accuracy of the technique allows for the identification of inherent field errors due to, for example, the winding layer transitions and the current leads. The alignment system is developed for the induction accelerator NDCX-II under construction at LBNL, an upgraded Neutralized Drift Compression experiment for research on warm dense matter and heavy ion fusion. Precise alignment is essential for NDCX-II, since the ion beam has a large energy spread associated with the rapid pulse compression such that misalignments lead to corkscrew deformation of the beam and reduced intensity at focus. The ability to align the magnetic axis of the pulsed solenoids to within 100 pm of the induction cell axis has been demonstrated.

  8. Circuit designs for measuring reactor period, peak power, and pulse fluence on TRIGA and other pulse reactor

    International Nuclear Information System (INIS)

    Meyer, R.D.; Thome, F.V.; Williams, R.L.

    1976-01-01

    Inexpensive circuits for use in evaluating reactor pulse prompt period, peak power, and pulse fluence (NVT) are presented. In addition to low cost, these circuits are easily assembled and calibrated and operate with a high degree of accuracy. The positive period measuring system has been used in evaluating reactivity additions as small as 5 cents (with an accuracy of ±0.1 cents) and as large as $4.50 (accuracy ±2 cents). Reactor peak power is measured digitally with a system accuracy of ±0.04% of a 10 Volt input (±4 mV). The NVT circuit measures over a 2-1/2 decade range, has 3 place resolution and an accuracy of better than 1%. (author)

  9. Treatment of dyeing wastewater including reactive dyes (Reactive ...

    African Journals Online (AJOL)

    Fungal growth was not observed at pH 2. Maximum fungal decolourisation ocurred at pH 3 for anionic reactive dyes (RR, RBB, RB) and pH 6 for cationic MB dye. The fungal dye bioremoval was associated with the surface charge of the fungus due to electrostatic interactions. Growing R. arrhizus strain decolourised 100% of ...

  10. Pulsed ultrasonic stir welding method

    Science.gov (United States)

    Ding, R. Jeffrey (Inventor)

    2013-01-01

    A method of performing ultrasonic stir welding uses a welding head assembly to include a plate and a rod passing through the plate. The rod is rotatable about a longitudinal axis thereof. In the method, the rod is rotated about its longitudinal axis during a welding operation. During the welding operation, a series of on-off ultrasonic pulses are applied to the rod such that they propagate parallel to the rod's longitudinal axis. At least a pulse rate associated with the on-off ultrasonic pulses is controlled.

  11. Pulse timing for cataclysmic variables

    International Nuclear Information System (INIS)

    Chester, T.J.

    1979-01-01

    It is shown that present pulse timing measurements of cataclysmic variables can be explained by models of accretion disks in these systems, and thus such measurements can constrain disk models. The model for DQ Her correctly predicts the amplitude variation of the continuum pulsation and can also perhaps explain the asymmetric amplitude of the pulsed lambda4686 emission line. Several other predictions can be made from the model. In particular, if pulse timing measurements that resolve emission lines both in wavelength and in binary phase can be made, the projected orbital radius of the white dwarf could be deduced

  12. Memory reactivation improves visual perception.

    Science.gov (United States)

    Amar-Halpert, Rotem; Laor-Maayany, Rony; Nemni, Shlomi; Rosenblatt, Jonathan D; Censor, Nitzan

    2017-10-01

    Human perception thresholds can improve through learning. Here we report findings challenging the fundamental 'practice makes perfect' basis of procedural learning theory, showing that brief reactivations of encoded visual memories are sufficient to improve perceptual discrimination thresholds. Learning was comparable to standard practice-induced learning and was not due to short training per se, nor to an epiphenomenon of primed retrieval enhancement. The results demonstrate that basic perceptual functions can be substantially improved by memory reactivation, supporting a new account of perceptual learning dynamics.

  13. Hyper dispersion pulse compressor for chirped pulse amplification systems

    Science.gov (United States)

    Barty, Christopher P. J.

    2011-11-29

    A grating pulse compressor configuration is introduced for increasing the optical dispersion for a given footprint and to make practical the application for chirped pulse amplification (CPA) to quasi-narrow bandwidth materials, such as Nd:YAG. The grating configurations often use cascaded pairs of gratings to increase angular dispersion an order of magnitude or more. Increased angular dispersion allows for decreased grating separation and a smaller compressor footprint.

  14. The history of cholinesterase reactivation: hydroxylamine and pyridinium aldoximes.

    Science.gov (United States)

    Petroianu, G A

    2012-10-01

    Hydroxylamine (NH2OH) the substance which will turn out to be of importance to those interested in the treatment of organophosporus cholinesterase inhibitor exposure, was synthesized by Wilhem Clemens Lossen in 1865 while working in Halle as an assistant in the laboratory of Wilhelm Heinrich Heintz. The Lossen synthesis generated hydroxylamine in aqueous solution. Anhydrous hydroxylamine was prepared almost simultaneously by Lobry de Bruyn and Crismer (1891). Using hydroxylamine as a starting point Meyer synthesized aldoximes and ketoximes (1897). Lange, a PhD student of Ladenburg, isolated 2-methyl-pyridine (alpha-picoline). Some fifty years later Wilson, working in the laboratory of Nachmansohn, demonstrated the ability of hydroxylamine to reactivate cholinesterase inhibited by organophosphates. Finally Wilson and Ginsburg using 2-methyl-pyridine as a starting point synthesized the first pyridinium aldoxime reactivator of clinical relevance, pralidoxime (1955).

  15. Active gated imaging in driver assistance system

    Science.gov (United States)

    Grauer, Yoav

    2014-04-01

    In this paper, we shall present the active gated imaging system (AGIS) in relation to the automotive field. AGIS is based on a fast-gated camera and pulsed illuminator, synchronized in the time domain to record images of a certain range of interest. A dedicated gated CMOS imager sensor and near infra-red (NIR) pulsed laser illuminator, is presented in this paper to provide active gated technology. In recent years, we have developed these key components and learned the system parameters, which are most beneficial to nighttime (in all weather conditions) driving in terms of field of view, illumination profile, resolution, and processing power. We shall present our approach of a camera-based advanced driver assistance systems (ADAS) named BrightEye™, which makes use of the AGIS technology in the automotive field.

  16. Application of digital process controller for automatic pulse operation in the NSRR

    International Nuclear Information System (INIS)

    Ishijima, K.; Ueda, T.; Saigo, M.

    1992-01-01

    The NSRR at JAERI is a modified TRIGA Reactor. It was built for investigating reactor fuel behavior under reactivity initiated accident (RIA) conditions. Recently, there has been a need to improve the flexibility of pulsing operations in the NSRR to cover a wide range of accidental situations, including RIA events at elevated power levels, and various abnormal power transients. To satisfy this need, we developed a new reactor control system which allows us to perform 'Shaped Pulse Operation: SP' and 'Combined Pulse Operation: CP'. Quick, accurate and complicated manipulation of control rods was required to realize these operations. Therefore we installed a new reactor control system, which we call an automatic pulse control system. This control system is composed of digital processing controllers and other digital equipments, and is fully automated and highly accurate. (author)

  17. Harmonic generation with a dual frequency pulse.

    Science.gov (United States)

    Keravnou, Christina P; Averkiou, Michalakis A

    2014-05-01

    Nonlinear imaging was implemented in commercial ultrasound systems over the last 15 years offering major advantages in many clinical applications. In this work, pulsing schemes coupled with a dual frequency pulse are presented. The pulsing schemes considered were pulse inversion, power modulation, and power modulated pulse inversion. The pulse contains a fundamental frequency f and a specified amount of its second harmonic 2f. The advantages and limitations of this method were evaluated with both acoustic measurements of harmonic generation and theoretical simulations based on the KZK equation. The use of two frequencies in a pulse results in the generation of the sum and difference frequency components in addition to the other harmonic components. While with single frequency pulses, only power modulation and power modulated pulse inversion contained odd harmonic components, with the dual frequency pulse, pulse inversion now also contains odd harmonic components.

  18. Pulsed Corona for Sustainable Technology

    International Nuclear Information System (INIS)

    Heesch, E.J.M. van; Pemen, A.J.M.; Yan, K.; Blom, P.P.M.; Huijbrechts, P.A.H.J.; Der Laan, P.C.T. van

    2000-01-01

    Highly active coronas with a peak power of up to 25 MW p/m corona wire and kJ/liter energy densities in the streamer channels can be produced by pulsed power. Since the voltage pulses are short, full breakdown does not occur even though the discharge currents are hundreds of Amperes. A matched pulsed power source can deposit up to 80% of its electrical energy into such a controlled discharge. Reliable and efficient sources characterized by 100 kV,150 ns wide pulses at 1000 Hz have passed 400 hours of operation. The area of applications is growing: VOC control, hot gas cleanup, water and air purification and sterilization. (author)

  19. Next generation Chirped Pulse Amplification

    Energy Technology Data Exchange (ETDEWEB)

    Nees, J; Biswal, S; Mourou, G [Univ. Michigan, Center for Ultrafast Optical Science, Ann Arbor, MI (United States); Nishimura, Akihiko; Takuma, Hiroshi

    1998-03-01

    The limiting factors of Chirped Pulse Amplification (CPA) are discussed and experimental results of CPA in Yb:glass regenerative amplifier are given. Scaling of Yb:glass to the petawatt level is briefly discussed. (author)

  20. Pulsed ventilation in mines. II

    Energy Technology Data Exchange (ETDEWEB)

    Krause, D

    1975-06-01

    Using test results, an attempt is made to determine the form of the free jet and to derive design data for pulsed fans. The most suitable placing of these fans for the ventilation of headings is discussed.

  1. Quantitative pulsed eddy current analysis

    International Nuclear Information System (INIS)

    Morris, R.A.

    1975-01-01

    The potential of pulsed eddy current testing for furnishing more information than conventional single-frequency eddy current methods has been known for some time. However, a fundamental problem has been analyzing the pulse shape with sufficient precision to produce accurate quantitative results. Accordingly, the primary goal of this investigation was to: demonstrate ways of digitizing the short pulses encountered in PEC testing, and to develop empirical analysis techniques that would predict some of the parameters (e.g., depth) of simple types of defect. This report describes a digitizing technique using a computer and either a conventional nuclear ADC or a fast transient analyzer; the computer software used to collect and analyze pulses; and some of the results obtained. (U.S.)

  2. Pulsed high-power beams

    International Nuclear Information System (INIS)

    Reginato, L.L.; Birx, D.L.

    1988-01-01

    The marriage of induction linac technology with nonlinear magnetic modulators has produced some unique capabilities. It is now possible to produce short-pulse electron beams with average currents measured in amperes, at gradients approaching 1-MeV/m, and with power efficiencies exceeding 50%. This paper reports on a 70-MeV, 3-kA induction accelerator (ETA II) constructed at the Lawrence Livermore National Laboratory that incorporates the pulse technology concepts that have evolved over the past several years. The ETA II is a linear induction accelerator and provides a test facility for demonstration of the high-average-power components and high-brightness sources used in such accelerators. The pulse drive of the accelerator is based on state-of-the-art magnetic pulse compressors with very high peak-power capability, repetition rates exceeding 1 kHz, and excellent reliability

  3. Foreign Assistance: Treasury's Technical Assistance Program

    National Research Council Canada - National Science Library

    Ford, Jess

    1999-01-01

    After the collapse of communism in Central Europe and the dissolution of the Soviet Union, the United States developed programs of technical assistance to help countries transition to market economies and democracy...

  4. Hydroxyl radical reactivity with diethylhydroxylamine

    International Nuclear Information System (INIS)

    Gorse, R.A. Jr.; Lii, R.R.; Saunders, B.B.

    1977-01-01

    Diethylhydroxylamine (DEHA) reacts with gas-phase hydroxyl radicals on every third collision, whereas the corresponding reaction in aqueous solution is considerably slower. The high gas-phase reactivity explains the predicted inhibitory effect of DEHA in atmospheric smog processes. Results from the studies in the aqueous phase are helpful in predicting the mechanism of the reaction of DEHA with hydroxyl radicals

  5. Backup passive reactivity shutdown systems

    International Nuclear Information System (INIS)

    Ashurko, Yu.M.; Kuznetsov, L.A.

    1996-01-01

    The paper reviews self-actuated shutdown systems (SASSs) for liquid metal-cooled fast reactors (LMFRs). Principles of operation are described, advantages and drawbacks analyzed, and prospects for application in advanced fast reactors examined. Ways to improve reactor self-protection via reactivity feedback amplification and related problems are discussed. (author). 9 refs, 12 figs

  6. Insertion material for controlling reactivity

    International Nuclear Information System (INIS)

    Baba, Iwao.

    1994-01-01

    Moderators and a group of suspended materials having substantially the same density as the moderator are sealed in a hollow rod vertically inserted to a fuel assembly. Specifically, the group of suspended materials is adapted to have a density changing stepwise from density of the moderator at the exit temperature of the reactor core to that at the inlet temperature of the reactor core. Reactivity is selectively controlled for a portion of high power and a portion of high reactivity by utilizing the density of the moderator and the distribution of the density. That is, if the power distribution is flat, the density of the moderators changes at a constant rate over the vertical direction of the reactor core and the suspended materials stay at a portion of the same density, to form a uniform distribution. Further, upon reactor shutdown, since the liquid temperature of the moderators is lowered and the density is increased, all of beads are collected at the upper portion to remove water at the upper portion of the reactor core of low burnup degree thereby selectively controlling the reactivity at a portion of high power and a portion of high reactivity. (N.H.)

  7. Treating water-reactive wastes

    International Nuclear Information System (INIS)

    Lussiez, G.W.

    1993-01-01

    Some compounds and elements, such as lithium hydride, magnesium, sodium, and calcium react violently with water to generate much heat and produce hydrogen. The hydrogen can ignite or even form an explosive mixture with air. Other metals may react rapidly only if they are finely divided. Some of the waste produced at Los Alamos National Laboratory includes these metals that are contaminated with radioactivity. By far the greatest volume of water-reactive waste is lithium hydride contaminated with depleted uranium. Reactivity of the water-reactive wastes is neutralized with an atmosphere of humid nitrogen, which prevents the formation of an explosive mixture of hydrogen and air. When we adjust the temperature of the nitrogen and the humidifier, the nitrogen can be more or less humid, and the rate of reaction can be adjusted and controlled. Los Alamos has investigated the rates of reaction of lithium hydride as a function of the temperature and humidity, and, as anticipated, they in with in temperature and humidity. Los Alamos will investigate other variables. For example, the nitrogen flow will be optimized to conserve nitrogen and yet keep the reaction rates high. Reaction rates will be determined for various forms of lithium waste, from small chips to powder. Bench work will lead to the design of a skid-mounted process for treating wastes. Other water-reactive wastes will also be investigated

  8. Reactive surfactants in heterophase polymerization

    NARCIS (Netherlands)

    Guyot, A.; Tauer, K.; Asua, J.M.; Es, van J.J.G.S.; Gauthier, C.; Hellgren, A.C.; Sherrington, D.C.; Montoya-Goni, A.; Sjöberg, M.; Sindt, O.; Vidal, F.F.M.; Unzue, M.; Schoonbrood, H.A.S.; Schipper, E.T.W.M.; Lacroix-Desmazes, P.

    1999-01-01

    This paper summarizes the work carried out during 3 years in a Network of the program "Human Capital and Mobility" of the European Union CHRX 93-0159 entitled "Reactive surfactants in heterophase polymerization for high performance polymers". A series of about 25 original papers will be published in

  9. Backup passive reactivity shutdown systems

    Energy Technology Data Exchange (ETDEWEB)

    Ashurko, Yu M; Kuznetsov, L A [Institute of Physics and Power Engineering, Obninsk (Russian Federation)

    1996-12-01

    The paper reviews self-actuated shutdown systems (SASSs) for liquid metal-cooled fast reactors (LMFRs). Principles of operation are described, advantages and drawbacks analyzed, and prospects for application in advanced fast reactors examined. Ways to improve reactor self-protection via reactivity feedback amplification and related problems are discussed. (author). 9 refs, 12 figs.

  10. Quantitative reactive modeling and verification.

    Science.gov (United States)

    Henzinger, Thomas A

    Formal verification aims to improve the quality of software by detecting errors before they do harm. At the basis of formal verification is the logical notion of correctness , which purports to capture whether or not a program behaves as desired. We suggest that the boolean partition of software into correct and incorrect programs falls short of the practical need to assess the behavior of software in a more nuanced fashion against multiple criteria. We therefore propose to introduce quantitative fitness measures for programs, specifically for measuring the function, performance, and robustness of reactive programs such as concurrent processes. This article describes the goals of the ERC Advanced Investigator Project QUAREM. The project aims to build and evaluate a theory of quantitative fitness measures for reactive models. Such a theory must strive to obtain quantitative generalizations of the paradigms that have been success stories in qualitative reactive modeling, such as compositionality, property-preserving abstraction and abstraction refinement, model checking, and synthesis. The theory will be evaluated not only in the context of software and hardware engineering, but also in the context of systems biology. In particular, we will use the quantitative reactive models and fitness measures developed in this project for testing hypotheses about the mechanisms behind data from biological experiments.

  11. Separability of local reactivity descriptors

    Indian Academy of Sciences (India)

    Unknown

    Abstract. The size-dependence of different local reactivity descriptors of dimer A2 and AB type of sys- tems is discussed. We derive analytic results of these descriptors calculated using finite difference approximation. In particular, we studied Fukui functions, relative electrophilicity and relative nucleo- philicity, local softness ...

  12. Reactive dual magnetron sputtering for large area application

    International Nuclear Information System (INIS)

    Struempfel, J.

    2002-01-01

    Production lines for large area coating demand high productivity of reactive magnetron sputtering processes. Increased dynamic deposition rates for oxides and nitrides were already obtained by using of highly powered magnetrons in combination with advanced sputter techniques. However, besides high deposition rates the uniformity of such coatings has to be carefully considered. First the basics of reactive sputtering processes and dual magnetron sputtering are summarized. Different methods for process stabilization and control are commonly used for reactive sputtering. The Plasma Emission Monitor (PE M) offers the prerequisite for fast acting process control derived from the in-situ intensity measurements of a spectral line of the sputtered target material. Combined by multiple Plasma Emission Monitor control loops segmented gas manifolds are able to provide excellent thin film uniformity at high deposition rates. The Dual Magnetron allows a broad range of processing by different power supply modes. Medium frequency, DC and pulsed DC power supplies can be used for high quality layers. Whereas the large area coating of highly isolating layers like TiO 2 or SiO 2 is dominated by MF sputtering best results for coating with transparent conductive oxides are obtained by dual DC powering of the dual magnetron arrangement. (Author)

  13. Pulsed ultrasonic stir welding system

    Science.gov (United States)

    Ding, R. Jeffrey (Inventor)

    2013-01-01

    An ultrasonic stir welding system includes a welding head assembly having a plate and a rod passing through the plate. The rod is rotatable about a longitudinal axis thereof. During a welding operation, ultrasonic pulses are applied to the rod as it rotates about its longitudinal axis. The ultrasonic pulses are applied in such a way that they propagate parallel to the longitudinal axis of the rod.

  14. Pulsed feedback defers cellular differentiation.

    Directory of Open Access Journals (Sweden)

    Joe H Levine

    2012-01-01

    Full Text Available Environmental signals induce diverse cellular differentiation programs. In certain systems, cells defer differentiation for extended time periods after the signal appears, proliferating through multiple rounds of cell division before committing to a new fate. How can cells set a deferral time much longer than the cell cycle? Here we study Bacillus subtilis cells that respond to sudden nutrient limitation with multiple rounds of growth and division before differentiating into spores. A well-characterized genetic circuit controls the concentration and phosphorylation of the master regulator Spo0A, which rises to a critical concentration to initiate sporulation. However, it remains unclear how this circuit enables cells to defer sporulation for multiple cell cycles. Using quantitative time-lapse fluorescence microscopy of Spo0A dynamics in individual cells, we observed pulses of Spo0A phosphorylation at a characteristic cell cycle phase. Pulse amplitudes grew systematically and cell-autonomously over multiple cell cycles leading up to sporulation. This pulse growth required a key positive feedback loop involving the sporulation kinases, without which the deferral of sporulation became ultrasensitive to kinase expression. Thus, deferral is controlled by a pulsed positive feedback loop in which kinase expression is activated by pulses of Spo0A phosphorylation. This pulsed positive feedback architecture provides a more robust mechanism for setting deferral times than constitutive kinase expression. Finally, using mathematical modeling, we show how pulsing and time delays together enable "polyphasic" positive feedback, in which different parts of a feedback loop are active at different times. Polyphasic feedback can enable more accurate tuning of long deferral times. Together, these results suggest that Bacillus subtilis uses a pulsed positive feedback loop to implement a "timer" that operates over timescales much longer than a cell cycle.

  15. Artistic Representation with Pulsed Holography

    International Nuclear Information System (INIS)

    Ishii, S

    2013-01-01

    This thesis describes artistic representation through pulsed holography. One of the prevalent practical problems in making holograms is object movement. Any movement of the object or film, including movement caused by acoustic vibration, has the same fatal results. One way of reducing the chance of movement is by ensuring that the exposure is very quick; using a pulsed laser can fulfill this objective. The attractiveness of using pulsed laser is based on the variety of materials or objects that can be recorded (e.g., liquid material or instantaneous scene of a moving object). One of the most interesting points about pulsed holograms is that some reconstructed images present us with completely different views of the real world. For example, the holographic image of liquid material does not appear fluid; it looks like a piece of hard glass that would produce a sharp sound upon tapping. In everyday life, we are unfamiliar with such an instantaneous scene. On the other hand, soft-textured materials such as a feather or wool differ from liquids when observed through holography. Using a pulsed hologram, we can sense the soft touch of the object or material with the help of realistic three-dimensional (3-D) images. The images allow us to realize the sense of touch in a way that resembles touching real objects. I had the opportunity to use a pulsed ruby laser soon after I started to work in the field of holography in 1979. Since then, I have made pulsed holograms of activities, including pouring water, breaking eggs, blowing soap bubbles, and scattering feathers and popcorn. I have also created holographic art with materials and objects, such as silk fiber, fabric, balloons, glass, flowers, and even the human body. Whenever I create art, I like to present the spectator with a new experience in perception. Therefore, I would like to introduce my experimental artwork through those pulsed holograms.

  16. The Toulouse pulsed magnet facility

    International Nuclear Information System (INIS)

    2006-01-01

    The 'Laboratoire National des Champs Magnetiques Pulses' (LNCMP) is an international user facility providing access to pulsed magnetic fields up to and beyond 60 T. The laboratory disposes of 10 magnet stations equipped with long-pulse magnets operating in the 35-60 T range and a short-pulse system reaching magnetic fields in excess of 70 T. The experimental infrastructure includes various high and low-temperature systems ranging from ordinary flow-type cryostats to dilution refrigerators reaching 50 mK, as well as different types of high-pressure cells. Experimental techniques include magnetization, transport, luminescence, IR-spectroscopy and polarimetry. The LNCMP pursues an extensive in-house research program focussing on all technological and scientific aspects of pulsed magnetic fields. Recent technical developments include the implementation of 60 T rapid-cooling coils, an 80 T prototype, a pulsed dipole magnet for optical investigations of dilute matter and a transportable horizontal access magnet for small angle x-ray scattering experiments. Scientific activities cover a variety of domains, including correlated electron systems, magnetism, semiconductors and nanoscience

  17. Pulsed Laser Interactions with Silicon Nano structures in Emitter Formation

    International Nuclear Information System (INIS)

    Huat, V.L.C.; Leong, C.S.; Kamaruzzaman Sopian, Saleem Hussain Zaidi

    2015-01-01

    Silicon wafer thinning is now approaching fundamental limits for wafer thickness owing to thermal expansion mismatch between Al and Si, reduced yields in wet-chemical processing as a result of fragility, and reduced optical absorption. An alternate manufacturing approach is needed to eliminate current manufacturing issues. In recent years, pulsed lasers have become readily available and costs have been significantly reduced. Pulsed laser interactions with silicon, in terms of micromachining, diffusions, and edge isolation, are well known, and have become industrial manufacturing tools. In this paper, pulsed laser interactions with silicon nano structures were identified as the most desirable solution for the fundamental limitations discussed above. Silicon nano structures have the capability for extremely high absorption that significantly reduces requirements for laser power, as well as thermal shock to the thinner wafer. Laser-assisted crystallization, in the presence of doping materials, leads to nano structure profiles that are highly desirable for sunlight absorption. The objective of this paper is the replacement of high temperature POCl_3 diffusion by laser-assisted phosphorus layers. With these improvements, complete low-temperature processing of thinner wafers was achievable with 3.7 % efficiency. Two-dimensional laser scanning was proved to be able to form uniformly annealed surfaces with higher fill factor and open-circuit voltage. (author)

  18. Square pulse linear transformer driver

    Directory of Open Access Journals (Sweden)

    A. A. Kim

    2012-04-01

    Full Text Available The linear transformer driver (LTD technological approach can result in relatively compact devices that can deliver fast, high current, and high-voltage pulses straight out of the LTD cavity without any complicated pulse forming and pulse compression network. Through multistage inductively insulated voltage adders, the output pulse, increased in voltage amplitude, can be applied directly to the load. The usual LTD architecture [A. A. Kim, M. G. Mazarakis, V. A. Sinebryukhov, B. M. Kovalchuk, V. A. Vizir, S. N Volkov, F. Bayol, A. N. Bastrikov, V. G. Durakov, S. V. Frolov, V. M. Alexeenko, D. H. McDaniel, W. E. Fowler, K. LeCheen, C. Olson, W. A. Stygar, K. W. Struve, J. Porter, and R. M. Gilgenbach, Phys. Rev. ST Accel. Beams 12, 050402 (2009PRABFM1098-440210.1103/PhysRevSTAB.12.050402; M. G. Mazarakis, W. E. Fowler, A. A. Kim, V. A. Sinebryukhov, S. T. Rogowski, R. A. Sharpe, D. H. McDaniel, C. L. Olson, J. L. Porter, K. W. Struve, W. A. Stygar, and J. R. Woodworth, Phys. Rev. ST Accel. Beams 12, 050401 (2009PRABFM1098-440210.1103/PhysRevSTAB.12.050401] provides sine shaped output pulses that may not be well suited for some applications like z-pinch drivers, flash radiography, high power microwaves, etc. A more suitable power pulse would have a flat or trapezoidal (rising or falling top. In this paper, we present the design and first test results of an LTD cavity that generates such a type of output pulse by including within its circular array a number of third harmonic bricks in addition to the main bricks. A voltage adder made out of a square pulse cavity linear array will produce the same shape output pulses provided that the timing of each cavity is synchronized with the propagation of the electromagnetic pulse.

  19. Long Silver Nanowires Synthesis by Pulsed Electrodeposition

    Directory of Open Access Journals (Sweden)

    M.R. Batevandi

    2015-09-01

    Full Text Available Silver nanowires were pulse electrodeposited into nanopore anodic alumina oxide templates. The effects of continuous and pulse electrodeposition waveform on the microstructure properties of the nanowire arrays were studied. It is seen that the microstructure of nanowire is depend to pulse condition. The off time duration of pulse waveform enables to control the growth direction of Ag nanowires.

  20. System for increasing laser pulse rate

    International Nuclear Information System (INIS)

    1980-01-01

    A technique of static elements is disclosed for combining a plurality of laser beams having time sequenced, pulsed radiation to achieve an augmented pulse rate. The technique may also be applied in a system for combining both time sequenced pulses and frequency distinct pulses for use in a system for isotope enrichment. (author)