WorldWideScience

Sample records for rapid laser heating

  1. Rapid heating of matter using high power lasers

    Energy Technology Data Exchange (ETDEWEB)

    Bang, Woosuk [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-04-08

    This slide presentation describes motivation (uniform and rapid heating of a target, opportunity to study warm dense matter, study of nuclear fusion reactions), rapid heating of matter with intense laser-driven ion beams, visualization of the expanding warm dense gold and diamond, and nuclear fusion experiments using high power lasers (direct heating of deuterium spheres (radius ~ 10nm) with an intense laser pulse.

  2. Rapid heating of solid density material by a petawatt laser

    Science.gov (United States)

    Evans, R. G.; Clark, E. L.; Eagleton, R. T.; Dunne, A. M.; Edwards, R. D.; Garbett, W. J.; Goldsack, T. J.; James, S.; Smith, C. C.; Thomas, B. R.; Clarke, R.; Neely, D. J.; Rose, S. J.

    2005-05-01

    Time-resolved x-ray spectra from solid targets irradiated by the VULCAN Petawatt laser focused to 1020Wcm-2 show that material at solid density is heated to temperatures above 500 eV to a depth of about 15 μm and for a duration of more than 30 ps. Modeling with the implicit hybrid plasma code LSP shows that the heating is sensitive to the laser prepulse through resistive inhibition of the laser accelerated electrons in the blow off layer.

  3. Rapid Embedded Wire Heating via Resistive Guiding of Laser-Generated Fast Electrons as a Hydrodynamic Driver

    CERN Document Server

    Robinson, A P L; Pasley, J

    2014-01-01

    Resistively guiding laser-generated fast electron beams in targets consisting of a resistive wire embedded in lower $Z$ material should allow one to rapidly heat the wire to over 100eV over a substantial distance without strongly heating the surrounding material. On the multi-ps timescale this can drive hydrodynamic motion in the surrounding material. Thus ultra-intense laser solid interactions have the potential as a controlled driver of radiation hydrodynamics in solid density material. In this paper we assess the laser and target parameters needed to achieve such rapid and controlled heating of the embedded wire.

  4. Blast-Wave Generation and Propagation in Rapidly Heated Laser-Irradiated Targets

    Science.gov (United States)

    Ivancic, S. T.; Stillman, C. R.; Nilson, P. M.; Solodov, A. A.; Froula, D. H.

    2017-10-01

    Time-resolved extreme ultraviolet (XUV) spectroscopy was used to study the creation and propagation of a >100-Mbar blast wave in a target irradiated by an intense (>1018WWcm2 cm2) laser pulse. Blast waves provide a platform to generate immense pressures in the laboratory. A temporal double flash of XUV radiation was observed when viewing the rear side of the target, which is attributed to the emergence of a blast wave following rapid heating by a fast-electron beam generated from the laser pulse. The time-history of XUV emission in the photon energy range of 50 to 200 eV was recorded with an x-ray streak camera with 7-ps temporal resolution. The heating and expansion of the target was simulated with an electron transport code coupled to 1-D radiation-hydrodynamics simulations. The temporal delay between the two flashes measured in a systematic study of target thickness and composition was found to evolve in good agreement with a Sedov-Taylor blast-wave solution. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944 and Department of Energy Office of Science Award Number DE-SC-0012317.

  5. Incubation behavior of silicon nanowire growth investigated by laser-assisted rapid heating

    Energy Technology Data Exchange (ETDEWEB)

    Ryu, Sang-gil; Kim, Eunpa; Grigoropoulos, Costas P., E-mail: cgrigoro@berkeley.edu [Department of Mechanical Engineering, University of California, Berkeley, California 94720-1740 (United States); Allen, Frances I.; Minor, Andrew M. [Department of Materials Science and Engineering, University of California, Berkeley, California 94720-1740 (United States); National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Hwang, David J. [Department of Mechanical Engineering, Stony Brook University, Stony Brook, New York 11794 (United States)

    2016-08-15

    We investigate the early stage of silicon nanowire growth by the vapor-liquid-solid mechanism using laser-localized heating combined with ex-situ chemical mapping analysis by energy-filtered transmission electron microscopy. By achieving fast heating and cooling times, we can precisely determine the nucleation times for nanowire growth. We find that the silicon nanowire nucleation process occurs on a time scale of ∼10 ms, i.e., orders of magnitude faster than the times reported in investigations using furnace processes. The rate-limiting step for silicon nanowire growth at temperatures in the vicinity of the eutectic temperature is found to be the gas reaction and/or the silicon crystal growth process, whereas at higher temperatures it is the rate of silicon diffusion through the molten catalyst that dictates the nucleation kinetics.

  6. Sinterable Ceramic Powders from Laser Heated Gas Phase Reactions and Rapidly Solidified Ceramic Materials.

    Science.gov (United States)

    1984-07-01

    Gattuso, T. R., Meunier, M., Adler, D., and Haggerty, J. S., "IR Laser- Induced Deposition of Silicon Thin Films ", to be published in the Proceedings of...and Thin Films by Laser Induced Gas Phase Reactions", presented at the Nineteenth University Conference on Ceramic Science, Emergent Process Methods... Silicon Carbonitrides from Monomeric Organosilicon Precursors". To be presented at the 1983 Annual Meeting of the American Ceramic Society, April 1983

  7. Laser Processed Heat Exchangers

    Science.gov (United States)

    Hansen, Scott

    2017-01-01

    The Laser Processed Heat Exchanger project will investigate the use of laser processed surfaces to reduce mass and volume in liquid/liquid heat exchangers as well as the replacement of the harmful and problematic coatings of the Condensing Heat Exchangers (CHX). For this project, two scale unit test articles will be designed, manufactured, and tested. These two units are a high efficiency liquid/liquid HX and a high reliability CHX.

  8. In Situ Synchrotron X-Ray Diffraction and Small Angle X-Ray Scattering Studies on Rapidly Heated and Cooled Ti-Al and Al-Cu-Mg Alloys Using Laser-Based Heating

    Science.gov (United States)

    Kenel, C.; Schloth, P.; Van Petegem, S.; Fife, J. L.; Grolimund, D.; Menzel, A.; Van Swygenhoven, H.; Leinenbach, C.

    2016-03-01

    Beam-based additive manufacturing (AM) typically involves high cooling rates in a range of 103-104 K/s. Therefore, new techniques are required to understand the non-equilibrium evolution of materials at appropriate time scales. Most technical alloys have not been optimized for such rapid solidification, and microstructural, phase, and elemental solubility behavior can be very different. In this work, the combination of complementary in situ synchrotron micro-x-ray diffraction (microXRD) and small angle x-ray scattering (SAXS) studies with laser-based heating and rapid cooling is presented as an approach to study alloy behavior under processing conditions similar to AM techniques. In rapidly solidified Ti-48Al, the full solidification and phase transformation sequences are observed using microXRD with high temporal resolution. The high cooling rates are achieved by fast heat extraction. Further, the temperature- and cooling rate-dependent precipitation of sub-nanometer clusters in an Al-Cu-Mg alloy can be studied by SAXS. The sensitivity of SAXS on the length scales of the newly formed phases allows their size and fraction to be determined. These techniques are unique tools to help provide a deeper understanding of underlying alloy behavior and its influence on resulting microstructures and properties after AM. Their availability to materials scientists is crucial for both in-depth investigations of novel alloys and also future production of high-quality parts using AM.

  9. Rapid freeze-drying cycle optimization using computer programs developed based on heat and mass transfer models and facilitated by tunable diode laser absorption spectroscopy (TDLAS).

    Science.gov (United States)

    Kuu, Wei Y; Nail, Steven L

    2009-09-01

    Computer programs in FORTRAN were developed to rapidly determine the optimal shelf temperature, T(f), and chamber pressure, P(c), to achieve the shortest primary drying time. The constraint for the optimization is to ensure that the product temperature profile, T(b), is below the target temperature, T(target). Five percent mannitol was chosen as the model formulation. After obtaining the optimal sets of T(f) and P(c), each cycle was assigned with a cycle rank number in terms of the length of drying time. Further optimization was achieved by dividing the drying time into a series of ramping steps for T(f), in a cascading manner (termed the cascading T(f) cycle), to further shorten the cycle time. For the purpose of demonstrating the validity of the optimized T(f) and P(c), four cycles with different predicted lengths of drying time, along with the cascading T(f) cycle, were chosen for experimental cycle runs. Tunable diode laser absorption spectroscopy (TDLAS) was used to continuously measure the sublimation rate. As predicted, maximum product temperatures were controlled slightly below the target temperature of -25 degrees C, and the cascading T(f)-ramping cycle is the most efficient cycle design. In addition, the experimental cycle rank order closely matches with that determined by modeling.

  10. Rapid prototyping with high power fiber lasers

    Energy Technology Data Exchange (ETDEWEB)

    Miranda, R.M. [Faculty of Sciences and Technology, New University Lisbon (Portugal); IDMEC, Instituto Superior Tecnico, TULISBON, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Lopes, G. [Welding Engineering Research Centre, Building 46, Cranfield University, Bedfordshire, MK43 0AL (United Kingdom); Quintino, L. [IDMEC, Instituto Superior Tecnico, TULISBON, Av. Rovisco Pais, 1049-001 Lisboa (Portugal)], E-mail: lquintino@ist.utl.pt; Rodrigues, J.P. [IDMEC, Instituto Superior Tecnico, TULISBON, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Williams, S. [Welding Engineering Research Centre, Building 46, Cranfield University, Bedfordshire, MK43 0AL (United Kingdom)

    2008-12-15

    Laser rapid prototyping technologies comprise a set of technologies used in a wide range of materials to produce prototypes or small batches of complex shaped components. This paper presents a research work on rapid prototyping technology with laser additive manufacture of wire based alloy Ti-6Al-4V with an 8 kW fiber laser for the production of components with cylindrical geometry. For this, an engineering system was developed, a demonstration part produced and the deposition process was characterized. Two processing parameters were investigated: and these were the relative position between the wire feeding system and the substrate and the laser beam to wire width ratio. The former affects the molten metal transfer mode and the pressure exerted by the wire tip on the molten pool, while the laser beam to wire width ratio affects the process efficiency, since this is a compromise of process stability and process speed. Both parameters control surface finishing and the smoothness of the part. The melting efficiency of the process is low when compared to alternative processes involving powder pre deposition, but the density of the part is improved with homogeneous structural characteristics.

  11. Rapid determination of vial heat transfer parameters using tunable diode laser absorption spectroscopy (TDLAS) in response to step-changes in pressure set-point during freeze-drying.

    Science.gov (United States)

    Kuu, Wei Y; Nail, Steven L; Sacha, Gregory

    2009-03-01

    The purpose of this study was to perform a rapid determination of vial heat transfer parameters, that is, the contact parameter K(cs) and the separation distance l(v), using the sublimation rate profiles measured by tunable diode laser absorption spectroscopy (TDLAS). In this study, each size of vial was filled with pure water followed by a freeze-drying cycle using a LyoStar II dryer (FTS Systems) with step-changes of the chamber pressure set-point at to 25, 50, 100, 200, 300, and 400 mTorr. K(cs) was independently determined by nonlinear parameter estimation using the sublimation rates measured at the pressure set-point of 25 mTorr. After obtaining K(cs), the l(v) value for each vial size was determined by nonlinear parameter estimation using the pooled sublimation rate profiles obtained at 25 to 400 mTorr. The vial heat transfer coefficient K(v), as a function of the chamber pressure, was readily calculated, using the obtained K(cs) and l(v) values. It is interesting to note the significant difference in K(v) of two similar types of 10 mL Schott tubing vials, primary due to the geometry of the vial-bottom, as demonstrated by the images of the contact areas of the vial-bottom. (c) 2008 Wiley-Liss, Inc. and the American Pharmacists Association

  12. Heat generation in laser irradiated tissue.

    Science.gov (United States)

    Welch, A J; Pearce, J A; Diller, K R; Yoon, G; Cheong, W F

    1989-02-01

    Many medical applications involving lasers rely upon the generation of heat within the tissue for the desired therapeutic effect. Determination of the absorbed light energy in tissue is difficult in many cases. Although UV wavelengths of the excimer laser and 10.6 microns wavelength of the CO2 laser are absorbed within the first 20 microns of soft tissue, visible and near infrared wavelengths are scattered as well as absorbed. Typically, multiple scattering is a significant factor in the distribution of light in tissue and the resulting heat source term. An improved model is presented for estimating heat generation due to the absorption of a collimated (axisymmetric) laser beam and scattered light at each point r and z in tissue. Heat generated within tissue is a function of the laser power, the shape and size of the incident beam and the optical properties of the tissue at the irradiation wavelength. Key to the calculation of heat source strength is accurate estimation of the light distribution. Methods for experimentally determining the optical parameters of tissue are discussed in the context of the improved model.

  13. Heat pump processes induced by laser radiation

    Science.gov (United States)

    Garbuny, M.; Henningsen, T.

    1980-01-01

    A carbon dioxide laser system was constructed for the demonstration of heat pump processes induced by laser radiation. The system consisted of a frequency doubling stage, a gas reaction cell with its vacuum and high purity gas supply system, and provisions to measure the temperature changes by pressure, or alternatively, by density changes. The theoretical considerations for the choice of designs and components are dicussed.

  14. Laser Processed Condensing Heat Exchanger Technology Development

    Science.gov (United States)

    Hansen, Scott; Wright, Sarah; Wallace, Sarah; Hamilton, Tanner; Dennis, Alexander; Zuhlke, Craig; Roth, Nick; Sanders, John

    2017-01-01

    The reliance on non-permanent coatings in Condensing Heat Exchanger (CHX) designs is a significant technical issue to be solved before long-duration spaceflight can occur. Therefore, high reliability CHXs have been identified by the Evolvable Mars Campaign (EMC) as critical technologies needed to move beyond low earth orbit. The Laser Processed Condensing Heat Exchanger project aims to solve these problems through the use of femtosecond laser processed surfaces, which have unique wetting properties and potentially exhibit anti-microbial growth properties. These surfaces were investigated to identify if they would be suitable candidates for a replacement CHX surface. Among the areas researched in this project include microbial growth testing, siloxane flow testing in which laser processed surfaces were exposed to siloxanes in an air stream, and manufacturability.

  15. Laser Pulse Heating of Spherical Metal Particles

    Directory of Open Access Journals (Sweden)

    Michael I. Tribelsky

    2011-12-01

    Full Text Available We consider the general problem of laser pulse heating of spherical metal particles with the sizes ranging from nanometers to millimeters. We employ the exact Mie solution of the diffraction problem and solve the heat-transfer equation to determine the maximum temperature rise at the particle surface as a function of optical and thermometric parameters of the problem. Primary attention is paid to the case when the thermal diffusivity of the particle is much larger than that of the environment, as it is in the case of metal particles in fluids. We show that, in this case, for any given duration of the laser pulse, the maximum temperature rise as a function of the particle size reaches a maximum at a certain finite size of the particle. We suggest simple approximate analytical expressions for this dependence, which cover the entire parameter range of the problem and agree well with direct numerical simulations.

  16. Hybrid heat capacity-moving slab solid-state laser

    Science.gov (United States)

    Stappaerts, Eddy A.

    2005-03-01

    Laser material is pumped and its stored energy is extracted in a heat capacity laser mode at a high duty factor. When the laser material reaches a maximum temperature, it is removed from the lasing region and a subsequent volume of laser material is positioned into the lasing region to repeat the lasing process. The heated laser material is cooled passively or actively outside the lasing region.

  17. Tritium Removal by Laser Heating and Its Application to Tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    C.H. Skinner; C.A. Gentile; G. Guttadora; A. Carpe; S. Langish; K.M. Young; M. Nishi; W. Shu

    2001-11-16

    A novel laser heating technique has recently been applied to removing tritium from carbon tiles that had been exposed to deuterium-tritium (DT) plasmas in the Tokamak Test Fusion Reactor (TFTR). A continuous wave neodymium laser, of power up to 300 watts, was used to heat the surface of the tiles. The beam was focused to an intensity, typically 8 kW/cm{sup 2}, and rapidly scanned over the tile surface by galvanometer-driven scanning mirrors. Under the laser irradiation, the surface temperature increased dramatically, and temperatures up to 2,300 degrees C were recorded by an optical pyrometer. Tritium was released and circulated in a closed-loop system to an ionization chamber that measured the tritium concentration. Most of the tritium (up to 84%) could be released by the laser scan. This technique appears promising for tritium removal in a next-step DT device as it avoids oxidation, the associated deconditioning of the plasma facing surfaces, and the expense of processing large quantities of tritium oxide. Some engineering aspects of the implementation of this method in a next-step fusion device will be discussed.

  18. Nozzle flow of laser-heated radiating hydrogen with application to a laser-heated rocket

    Science.gov (United States)

    Kemp, N. H.; Root, R. G.

    1977-01-01

    This paper presents a model for the steady heating of flowing hydrogen by a CW 10.6 micron laser, to consider the feasibility of a laser-heated rocket. The hydrogen flow and the laser beam are parallel, and move into a converging-diverging nozzle. The absorption of laser energy is initiated by a laser-supported combustion wave. The hydrogen is in chemical equilibrium, absorbs laser energy by inverse Bremsstrahlung, and loses energy by radiation. The hydrogen flow was calculated from the rear of the LSC wave to the throat. Estimates of convective heat losses were made using a hydrogen boundary layer analysis. Specific impulse, obtained by expanding isentropically from the throat to 1 atm or a vacuum, varies from 1400 to 3000 s. Radiation losses are 5 to 20%, though the energy fluxes to the walls are quite high. Convective loss estimates are high enough to indicate that coupling to the hot gas flow is required for a 10 kW engine, but not for a 5 MW engine.

  19. Induction heat treatment of laser welds

    DEFF Research Database (Denmark)

    Bagger, Claus; Olsen, Flemming Ove; Sørensen, Joakim Ilsing

    2003-01-01

    750º to 450º C. Initially, a simple analytical model was used to calculate the ideal energy contributions from a CO2 high power laser source together with an induction heat source such that the temperature can be kept at 600º C for 2.5 seconds. This knowledge was then used for the design......In this paper, a new approach based on induction heat-treatment of flat laser welded sheets is presented. With this new concept, the ductility of high strength steels GA260 with a thickness of 1.8 mm and CMn with a thickness of 2.13 mm is believed to be improved by prolonging the cooling time from...... of an induction coil. A number of systematic laboratory tests were then performed in order to study the effects of the coil on bead-on-plate laser welded samples. In these tests, important parameters such as coil current and distance between coil and sample were varied. Temperature measurements were made...

  20. Deuterium desorption from tungsten using laser heating

    Directory of Open Access Journals (Sweden)

    J.H. Yu

    2017-08-01

    Full Text Available Retention and desorption of hydrogenic species need to be accurately modeled to predict the tritium inventory of next generation fusion devices, which is needed both for tritium fuel recovery and for tritium safety concerns. In this paper, experiments on thermal desorption of deuterium from intrinsic polycrystalline tungsten defects using laser heating are compared to TMAP-7 modeling. The samples during deuterium plasma exposure were at a temperature of 373K for this benchmark study with ion fluence of 0.7–1.0 ×1024Dm−2. Following plasma exposure, a fiber laser (λ= 1100nm heated the samples to peak surface temperatures ranging from ∼500 to 1400K with pulse widths from 10ms to 1s, and 1 to 10 pulses applied to each sample. The remaining deuterium retention was measured using temperature programmed desorption (TPD. Results show that > 95% of deuterium is desorbed when the peak surface temperature reached ∼950K for > 1s. TMAP-7 is used to predict deuterium desorption from tungsten for a range of surface temperatures and heating durations, and is compared to previous work on desorption from beryllium codeposits.

  1. Process map for laser heat treatment of carbon steels

    Science.gov (United States)

    Ki, Hyungson; So, Sangwoo

    2012-10-01

    We propose a process map for diode-laser heat treatment of carbon steels. After first identifying a heat treatable region in terms of laser intensity and interaction time using a heat conduction model, two most important factors in heat treatment, carbon diffusion time in austenite and cooling time, are calculated and plotted in the heat treatable region. Because overall characteristics of laser heat treatment for a given steel type can be graphically visualized on a map, this map can be used in the determination of optimal process parameters. Hardening depth is also calculated using the concept of the critical effective carbon diffusion time. For demonstration and validation purposes, we have systematically conducted laser heat treatment on AISI 1020 and 1035 steel specimens using a 3 kW diode laser and measured surface hardness and hardening depth. The experimental results are in agreement with the calculated process map.

  2. Bone tissue heating and ablation by short and ultrashort laser pulses

    Science.gov (United States)

    Letfullin, Renat R.; Rice, Colin E. W.; George, Thomas F.

    2010-02-01

    Biological hard tissues, such as those found in bone and teeth, are complex tissues that build a strong mineral structure over an organic matrix framework. The laser-matter interaction for bone hard tissues holds great interest to laser surgery and laser dentistry; the use of short/ultrashort pulses, in particular, shows interesting behaviors not seen in continuous wave lasers. High laser energy densities in ultrashort pulses can be focused on a small irradiated surface (spot diameter is 10-50 μm) leading to rapid temperature rise and thermal ablation of the bone tissue. Ultrashort pulses, specifically those in the picosecond and femtosecond ranges, impose several challenges in modeling bone tissue response. In the present paper we perform time-dependent thermal simulations of short and ultrashort pulse laser-bone interactions in singlepulse and multipulse (set of ultrashort pulses) modes of laser heating. A comparative analysis for both radiation modes is discussed for laser heating of different types of the solid bone on the nanosecond, picosecond and femtosecond time scales. It is shown that ultrashort laser pulses with high energy densities can ablate bone tissue without heating tissues bordering the ablation creator. This reaction is particularly desirable as heat accumulation and thermal damage are the main factors affecting tissue regrowth rates, and thus patient recovery times.

  3. In-volume heating using high-power laser diodes

    NARCIS (Netherlands)

    Denisenkov, V.S.; Kiyko, V.V.; Vdovin, G.V.

    2015-01-01

    High-power lasers are useful instruments suitable for applications in various fields; the most common industrial applications include cutting and welding. We propose a new application of high-power laser diodes as in-bulk heating source for food industry. Current heating processes use surface

  4. Ultrashort Laser Pulse Heating of Nanoparticles: Comparison of Theoretical Approaches

    Directory of Open Access Journals (Sweden)

    Renat R. Letfullin

    2008-01-01

    Full Text Available The interaction between nanoparticles and ultrashort laser pulses holds great interest in laser nanomedicine, introducing such possibilities as selective cell targeting to create highly localized cell damage. Two models are studied to describe the laser pulse interaction with nanoparticles in the femtosecond, picosecond, and nanosecond regimes. The first is a two-temperature model using two coupled diffusion equations: one describing the heat conduction of electrons, and the other that of the lattice. The second model is a one-temperature model utilizing a heat diffusion equation for the phonon subsystem and applying a uniform heating approximation throughout the particle volume. A comparison of the two modeling strategies shows that the two-temperature model gives a good approximation for the femtosecond mode, but fails to accurately describe the laser heating for longer pulses. On the contrary, the simpler one-temperature model provides an adequate description of the laser heating of nanoparticles in the femtosecond, picosecond, and nanosecond modes.

  5. Laser pulse heating of surfaces and thermal stress analysis

    CERN Document Server

    Yilbas, Bekir S; Al-Aqeeli, Nasser; Al-Qahtani, Hussain M

    2013-01-01

    This book introduces laser pulse heating and thermal stress analysis in materials surface. Analytical temperature treatments and stress developed in the surface region are also explored. The book will help the reader analyze the laser induced stress in the irradiated region and presents solutions for the stress field. Detailed thermal stress analysis in different laser pulse heating situations and different boundary conditions are also presented. Written for surface engineers.

  6. Optical heating and rapid transformation of functionalized fullerenes.

    Science.gov (United States)

    Krishna, Vijay; Stevens, Nathanael; Koopman, Ben; Moudgil, Brij

    2010-05-01

    Irradiating single-walled carbon nanotubes can lead to heat generation or ignition. These processes could be used in medical and industrial applications, but the poor solvent compatibility and high aspect ratios of nanotubes have led to concerns about safety. Here, we show that certain functionalized fullerenes, including polyhydroxy fullerenes (which are known to be environmentally safe and to have therapeutic properties) are heated or ignited by exposure to low-intensity (fullerenes and other functionalized fullerenes can be transformed into single-walled nanotubes, multiwalled nanotubes and carbon onions without the presence of a catalyst by exposure to low-intensity laser irradiation in an oxygen-free environment. To demonstrate the potential usefulness of these processes in applications, we disrupted animal cells dosed with polyhydroxy fullerenes by exposing them to a near-infrared laser for a few seconds, and also ignited an explosive charge in contact with a particle of carboxy fullerenes.

  7. Thermodynamic properties of pulverized coal during rapid heating devolatilization processes

    Energy Technology Data Exchange (ETDEWEB)

    Proscia, W.M.; Freihaut, J.D. [United Technologies Research Center, E. Hartford, CT (United States); Rastogi, S.; Klinzing, G.E. [Univ. of Pittsburg, PA (United States)

    1994-07-01

    The thermodynamic properties of coal under conditions of rapid heating have been determined using a combination of UTRC facilities including a proprietary rapid heating rate differential thermal analyzer (RHR-DTA), a microbomb calorimeter (MBC), an entrained flow reactor (EFR), an elemental analyzer (EA), and a FT-IR. The total heat of devolatilization, was measured for a HVA bituminous coal (PSOC 1451D, Pittsburgh No. 8) and a LV bituminous coal (PSOC 1516D, Lower Kittaning). For the HVA coal, the contributions of each of the following components to the overall heat of devolatilization were measured: the specific heat of coal/char during devolatilization, the heat of thermal decomposition of the coal, the specific heat capacity of tars, and the heat of vaporization of tars. Morphological characterization of coal and char samples was performed at the University of Pittsburgh using a PC-based image analysis system, BET apparatus, helium pcynometer, and mercury porosimeter. The bulk density, true density, CO{sub 2} surface area, pore volume distribution, and particle size distribution as a function of extent of reaction are reported for both the HVA and LV coal. Analyses of the data were performed to obtain the fractal dimension of the particles as well as estimates for the external surface area. The morphological data together with the thermodynamic data obtained in this investigation provides a complete database for a set of common, well characterized coal and char samples. This database can be used to improve the prediction of particle temperatures in coal devolatilization models. Such models are used both to obtain kinetic rates from fundamental studies and in predicting furnace performance with comprehensive coal combustion codes. Recommendations for heat capacity functions and heats of devolatilization for the HVA and LV coals are given. Results of sample particle temperature calculations using the recommended thermodynamic properties are provided.

  8. Cavitation and acoustic emission around laser-heated microparticles

    Science.gov (United States)

    Lin, Charles P.; Kelly, Michael W.

    1998-06-01

    We studied transient cavitation bubble formation and acoustic emission around individual laser-heated microparticles using subnanosecond time-resolved microscopy. Microcavitation bubbles were observed as early as 0.5 ns after the particles were heated by a 30 ps laser pulse. The bubbles expanded to a few micrometers in size and collapsed on the time scale of 0.1-1 μsec. We discuss microcavitation as the origin of anomalously large photoacoustic effects and nonlinear optical responses observed in laser-heated colloidal suspensions, as well as a mechanism for cellular damage in biologic tissue containing pigment particles.

  9. Rapid Nanoparticle Synthesis by Magnetic and Microwave Heating

    Directory of Open Access Journals (Sweden)

    Viktor Chikan

    2016-05-01

    Full Text Available Traditional hot-injection (HI syntheses of colloidal nanoparticles (NPs allows good separation of the nucleation and growth stages of the reaction, a key limitation in obtaining monodisperse NPs, but with limited scalability. Here, two methods are presented for obtaining NPs via rapid heating: magnetic and microwave-assisted. Both of these techniques provide improved engineering control over the separation of nucleation and growth stages of nanomaterial synthesis when the reaction is initiated from room temperature. The advantages of these techniques with preliminary data are presented in this prospective article. It is shown here that microwave assisted heating could possibly provide some selectivity in activating the nanomaterial precursor materials, while magnetic heating can produce very tiny particles in a very short time (even on the millisecond timescale, which is important for scalability. The fast magnetic heating also allows for synthesizing larger particles with improved size distribution, therefore impacting, not only the quantity, but the quality of the nanomaterials.

  10. Laser production and heating of plasma for MHD application

    Science.gov (United States)

    Jalufka, N. W.

    1988-01-01

    Experiments have been made on the production and heating of plasmas by the absorption of laser radiation. These experiments were performed to ascertain the feasibility of using laser-produced or laser-heated plasmas as the input for a magnetohydrodynamic (MHD) generator. Such a system would have a broad application as a laser-to-electricity energy converter for space power transmission. Experiments with a 100-J-pulsed CO2 laser were conducted to investigate the breakdown of argon gas by a high-intensity laser beam, the parameters (electron density and temperature) of the plasma produced, and the formation and propagation of laser-supported detonation (LSD) waves. Experiments were also carried out using a 1-J-pulsed CO2 laser to heat the plasma produced in a shock tube. The shock-tube hydrogen plasma reached electron densities of approximately 10 to the 17th/cu cm and electron temperatures of approximately 1 eV. Absorption of the CO2 laser beam by the plasma was measured, and up to approximately 100 percent absorption was observed. Measurements with a small MHD generator showed that the energy extraction efficiency could be very large with values up to 56 percent being measured.

  11. Synthesis of CVD-graphene on rapidly heated copper foils.

    Science.gov (United States)

    Kim, Sang-Min; Kim, Jae-Hyun; Kim, Kwang-Seop; Hwangbo, Yun; Yoon, Jong-Hyuk; Lee, Eun-Kyu; Ryu, Jaechul; Lee, Hak-Joo; Cho, Seungmin; Lee, Seung-Mo

    2014-05-07

    Most chemical vapor deposition (CVD) systems used for graphene growth mainly employ convection and radiation heat transfer between the heating source and the metal catalyst in order to reach the activation temperature of the reaction, which in general leads to a long synthesis time and poor energy efficiency. Here, we report a highly time- and energy-efficient CVD setup, in which the metal catalyst (Cu) is designed to be physically contacted with a heating source to give quick heat transfer by conduction. The induced conduction heating enabled the usual effects of the pretreatment and annealing of Cu (i.e., annihilation of surface defects, impurities and contaminants) to be achieved in a significantly shorter time compared to conventional CVD. Notably, the rapid heating was observed to lead to larger grains of Cu with high uniformity as compared to the Cu annealed by conventional CVD, which are believed to be beneficial for the growth of high quality graphene. Through this CVD setup, bundles of high quality (∼252 Ω per square) and large area (over 16 inch) graphenes were able to be readily synthesized in 40 min in a significantly efficient way. When considering ease of scalability, high energy effectiveness and considerable productivity, our method is expected to be welcomed by industrialists.

  12. Study, optimization, and design of a laser heat engine

    Science.gov (United States)

    1978-01-01

    Laser heat engine concepts, proposed for satellite applications, were analyzed to determine which engine concepts best meet the requirements of high efficiency (50 percent or better) continuous operation in space. The best laser heat engine for a near-term experimental demonstration, selected on the basis of high overall operating efficiency, high power-to-weight characteristics, and availability of the required technology, is an Otto/Diesel cycle piston engine using a diamond window to admit CO2 laser radiation. The technology with the greatest promise of scaling to megawatt power levels in the long term is the energy exchanger/gas turbine combination.

  13. Rapid Heat Treatment of Aluminum High-Pressure Diecastings

    Science.gov (United States)

    Lumley, R. N.; Polmear, I. J.; Curtis, P. R.

    2009-07-01

    Recently, it has been demonstrated that common high-pressure diecasting (HPDC) alloys, such as those based on the Al-Si-Cu and Al-Si-Mg-(Cu) systems, may be successfully heat treated without causing surface blistering or dimensional instability. In some compositions, the capacity to exploit age hardening may allow the proof stress values to be doubled when compared to the as-cast condition. This heat treatment procedure involves the use of severely truncated solution treatment cycles conducted at lower than normal temperatures, followed by quenching and natural or artificial aging. The potential therefore exists to develop and evaluate secondary HPDC alloys designed specifically for rapid heat treatment, while still displaying high castability. This article reports results of an experimental program in which responses of various alloy compositions to age hardening have been investigated with the primary aim of further reducing the duration and cost of the heat treatment cycle while maintaining high tensile properties. Composition ranges have been established for which values of 0.2 pct proof stress exceeding 300 MPa ( i.e., increases of ~100 pct above as-cast values) can be achieved using a procedure that involves a total time for solution treatment plus age hardening of only 30 minutes. This rapid aging behavior is shown to be related to precipitation of the complex Q' phase, which forms primarily when Mg contents of the alloys are above ~0.2 wt pct.

  14. Surface hardening using cw CO2 laser: laser heat treatment, modelation, and experimental work

    Science.gov (United States)

    Muniz, German; Alum, Jorge

    1996-02-01

    In the present work are given the results of the application of laser metal surface hardening techniques using a cw carbon dioxide laser as an energy source on steel 65 G. The laser heat treatment results are presented theoretically and experimentally. Continuous wave carbon dioxide laser of 0.6, 0.3, and 0.4 kW were used. A physical model for the descriptions of the thermophysical laser metal interactions process is given and a numerical algorithm is used to solve this problem by means of the LHT code. The results are compared with the corresponding experimental ones and a very good agreement is observed. The LHT code is able to do predictions of transformation hardening by laser heating. These results will be completed with other ones concerning laser alloying and cladding presented in a second paper.

  15. Advances in rapid cooling treatment for heat stroke

    Directory of Open Access Journals (Sweden)

    Jia-jia ZHAO

    2014-10-01

    Full Text Available Heat stroke is a life-threatening disease characterized clinically by central nervous system dysfunction and severe hyperthermia (core temperature rises to higher than 40℃. The unchecked rise of body core temperature overwhelms intrinsic or extrinsic heat generation mechanism, thus overwhelms homoeostatic thermoregulation. Hyperthermia causes cellular and organ dysfunction with progressive exacerbation resulting in multi-organ failure and death. Rapid cooling to reduce core temperature as quickly as possible is the primary and most effective treatment, as it has been shown that the major determinant of outcome in heatstroke is the degree and duration of hyperthermia. If suppression of body temperature is delayed, the fatality rate will be elevated. Several cooling methods are available, including physical cooling by conduction, convection and evaporation with ice/cold water immersion, internal cooling by invasive methods such as hemofiltration, intravascular cooling, cold water gastric and rectal lavage, and cooling with drugs. It is crucial to formulate a scientific and reasonable strategy for the subsequent treatment in accordance with the patient's physical condition, the condition of cooling equipment, and the manipulator's proficiency in cooling methods and equipment usage. This article reviews the domestic and international advances in study of rapid and efficient cooling measures for heat stroke. DOI: 10.11855/j.issn.0577-7402.2014.10.17

  16. Update on Modular Laser Launch System and Heat Exchanger Thruster

    Science.gov (United States)

    Kare, Jordin T.

    2011-11-01

    The heat-exchanger (HX) thruster and modular laser array provide a comparatively low-risk route to a ground-to-orbit laser launch system. Recently, the reference designs for the propulsion system, laser array, and overall launch system have evolved significantly. By combining a variable flow of dense propellant with the primary hydrogen propellant, the heat exchanger thruster can trade reduced Isp for increased thrust at liftoff, with minimal increase in tank mass. Single-mode CW fiber lasers up to 10 kW power allow a beam module to be built with off-the-shelf commercial lasers. Low-cost high-radiance laser diode arrays can deliver launch-level fluxes of 5-10 MW/m2 over tens of kilometers, sufficient to power a vehicle through the atmosphere, and high enough to hand off propulsion to a main laser array several hundred kilometers downrange. These and other enhancements enable a system design with a true single-stage vehicle in which the only component not yet demonstrated is the silicon-carbide heat exchanger itself.

  17. Stochastic heating in laser interaction with ultra-thin foils

    Science.gov (United States)

    Luis Martins, Joana; Siminos, Evangelos; Fulop, Tunde

    2017-10-01

    Stochastic heating of electrons in multiple counter-propagating electromagnetic waves has been investigated theoretically and numerically in numerous works since the 80s (e.g. Ref.). Stochastic heating has been invoked as a possible mechanism responsible for electron heating in scenarios such as laser interaction with thin foils for ion acceleration and electron heating in beat-wave injection. However, a clear experimental verification of this heating process has not been done, to our knowledge. In this work, we examine electron heating during the interaction of multiple laser pulses with ultra-thin foils (a few atomic layers wide) through numerical particle-in-cell and particle-particle simulations. Such targets could prevent the development of instabilities/processes which could hinder the interpretation of observations. We include realistic temporally and spatially finite laser pulses and targets and explore in detail possible setups for an experimental observation of stochastic heating, analyzing signatures in the electron energy spectra, angular distribution, and radiation emission.

  18. Enthalpy model for heating, melting, and vaporization in laser ablation

    Directory of Open Access Journals (Sweden)

    Vasilios Alexiades

    2010-09-01

    Full Text Available Laser ablation is used in a growing number of applications in various areas including medicine, archaeology, chemistry, environmental and materials sciences. In this work the heat transfer and phase change phenomena during nanosecond laser ablation of a copper (Cu target in a helium (He background gas at atmospheric pressure are presented. An enthalpy model is outlined, which accounts for heating, melting, and vaporization of the target. As far as we know, this is the first model that connects the thermodynamics and underlying kinetics of this challenging phase change problem in a self-consistent way.

  19. Rapid solidification in laser welding of stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Zambon, A. (Univ. di Padova (Italy)); Bonollo, F.

    1994-04-30

    The microstructural characterization of both weld beads and heat affected zones (HAZ) was carried out on austenitic (AISI 304, 316) and duplex (UNS 31803) stainless steels, laser welded under various working parameters (power, traverse speed, shielding gas), by means of light microscopy, SEM, TEM, and image analysis, with the aim of pointing out changes in the amounts of the present phases, with respect to those predicted by equilibrium diagrams. Moreover, an analytical thermal model of laser beam welding was employed in order to evaluate the cooling rates involved in the process. The thermal field analysis, checked by comparing the calculated and the actual weld beads, has been used as a tool aimed at correlating cooling rates and microstructural characteristics. (orig.)

  20. Transport of laser accelerated proton beams and isochoric heating of matter

    Energy Technology Data Exchange (ETDEWEB)

    Roth, M; Alber, I; Guenther, M; Harres, K [Inst. fuer Kernphysik, Technische Universitaet Darmstadt, 64289 Darmstadt (Germany); Bagnoud, V [GSI Helmholtzzentrum f. Schwerionenforschung GmbH, 64291 Darmstadt (Germany); Brown, C; Gregori, G [Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Clarke, R; Heathcote, R; Li, B [STFC, Rutherford Appleton Laboratory, Chilton, Didcot, OX14 OQX (United Kingdom); Daido, H [Photo Medical Research Center, JAEA, Kizugawa-City, Kyoto 619-0215 (Japan); Fernandez, J; Flippo, K; Gaillard, S; Gauthier, C [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Glenzer, S; Kritcher, A; Kugland, N; LePape, S [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Makita, M, E-mail: markus.roth@physik.tu-darmstadt.d [School of Mathematics and Physics, Queen' s University of Belfast, Belfast BT7 1NN (United Kingdom)

    2010-08-01

    The acceleration of intense proton and ion beams by ultra-intense lasers has matured to a point where applications in basic research and technology are being developed. Crucial for harvesting the unmatched beam parameters driven by the relativistic electron sheath is the precise control of the beam. We report on recent experiments using the PHELIX laser at GSI, the VULCAN laser at RAL and the TRIDENT laser at LANL to control and use laser accelerated proton beams for applications in high energy density research. We demonstrate efficient collimation of the proton beam using high field pulsed solenoid magnets, a prerequisite to capture and transport the beam for applications. Furthermore we report on two campaigns to use intense, short proton bunches to isochorically heat solid targets up to the warm dense matter state. The temporal profile of the proton beam allows for rapid heating of the target, much faster than the hydrodynamic response time thereby creating a strongly coupled plasma at solid density. The target parameters are then probed by X-ray Thomson scattering (XRTS) to reveal the density and temperature of the heated volume. This combination of two powerful techniques developed during the past few years allows for the generation and investigation of macroscopic samples of matter in states present in giant planets or the interior of the earth.

  1. Simulation of Microstructure during Laser Rapid Forming Solidification Based on Cellular Automaton

    Directory of Open Access Journals (Sweden)

    Zhi-jian Wang

    2014-01-01

    Full Text Available The grain microstructure of molten pool during the solidification of TC4 titanium alloy in the single point laser cladding was investigated based on the CAFE model which is the cellular automaton (CA coupled with the finite element (FE method. The correct temperature field is the prerequisite for simulating the grain microstructure during the solidification of the molten pool. The model solves the energy equation by the FE method to simulate the temperature distribution in the molten pool of the single point laser cladding. Based on the temperature field, the solidification microstructure of the molten pool is also simulated with the CAFE method. The results show that the maximum temperature in the molten pool increases with the laser power and the scanning rate. The laser power has a larger influence on the temperature distribution of the molten pool than the scanning rate. During the solidification of the molten pool, the heat at the bottom of the molten pool transfers faster than that at the top of the molten pool. The grains rapidly grow into the molten pool, and then the columnar crystals are formed. This study has a very important significance for improving the quality of the structure parts manufactured through the laser cladding forming.

  2. Interaction of gold nanoparticles with nanosecond laser pulses: Nanoparticle heating

    Energy Technology Data Exchange (ETDEWEB)

    Nedyalkov, N.N., E-mail: nnn_1900@yahoo.com [Institute of Electronics, Bulgarian Academy of Sciences, Tzarigradsko shousse 72, Sofia 1784 (Bulgaria); Imamova, S.E.; Atanasov, P.A. [Institute of Electronics, Bulgarian Academy of Sciences, Tzarigradsko shousse 72, Sofia 1784 (Bulgaria); Toshkova, R.A.; Gardeva, E.G.; Yossifova, L.S.; Alexandrov, M.T. [Institute of Experimental Pathology and Parasitology, Bulgarian Academy of Sciences, G. Bonchev Street, bl. 25, Sofia 1113 (Bulgaria); Obara, M. [Department of Electronics and Electrical Engineering, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan)

    2011-04-01

    Theoretical and experimental results on the heating process of gold nanoparticles irradiated by nanosecond laser pulses are presented. The efficiency of particle heating is demonstrated by in-vitro photothermal therapy of human tumor cells. Gold nanoparticles with diameters of 40 and 100 nm are added as colloid in the cell culture and the samples are irradiated by nanosecond pulses at wavelength of 532 nm delivered by Nd:YAG laser system. The results indicate clear cytotoxic effect of application of nanoparticle as more efficient is the case of using particles with diameter of 100 nm. The theoretical analysis of the heating process of nanoparticle interacting with laser radiation is based on the Mie scattering theory, which is used for calculation of the particle absorption coefficient, and two-dimensional heat diffusion model, which describes the particle and the surrounding medium temperature evolution. Using this model the dependence of the achieved maximal temperature in the particles on the applied laser fluence and time evolution of the particle temperature is obtained.

  3. Moving heat source in a confined channel: Heat transfer and boiling in endovenous laser ablation of varicose veins

    NARCIS (Netherlands)

    de Boer, Amit; Oliveira, Jorge L. G.; van der Geld, Cees W. M.; Malskat, Wendy S. J.; van den Bos, Renate; Nijsten, Tamar; van Gemert, Martin J. C.

    2017-01-01

    Motion of a moving laser light heat source in a confined volume has important applications such as in endovenous laser ablation (EVLA) of varicose veins. This light heats up the fluid and the wall volume by absorption and heat conduction. The present study compares the flow and temperature fields in

  4. Quantitative effects of rapid heating on soot-particle sizing through analysis of two-pulse LII

    KAUST Repository

    Cenker, Emre

    2017-02-27

    During the rapid laser pulse heating and consecutive cooling in laser-induced incandescence (LII), soot particles may undergo thermal annealing and sublimation processes which lead to a permanent change in its optical properties and its primary particle size, respectively. Overall, effects of these two processes on soot and LII model-based particle sizing are investigated by measuring the two-color time-resolved (2C-TiRe) LII signal decay from in-flame soot after two consecutive laser pulses at 1064-nm wavelength. Experiments are carried out on a non-premixed laminar ethylene/air flame from a Santoro burner with both low and moderate laser fluences suitable for particle sizing. The probe volume is set to a radial position close to the flame axis where the soot particles are known to be immature or less graphitic. With the first pulse, soot is pre-heated, and the LII signal after the consecutive second pulse is used for analysis. The two-color incandescence emission technique is used for the pyrometric determination of the LII-heated peak soot temperature at the second pulse. A new LII simulation tool is developed which accounts for particle heating via absorption and annealing, and cooling via sublimation, conduction, and radiation with various existing sub-models from the literature. The same approach of using two laser pulses is implemented in the simulations. Measurements indicate that thermal annealing and associated absorption enhancement becomes important at laser fluences above 0.17 J/cm2 for the immature in-flame soot. After a heating pulse at 0.33 J/cm2, the increase of the soot absorption function is calculated as 35% using the temperature measured at the second pulse and an absorption model based on the Rayleigh approximation. Present annealing model, on the other hand, predicts graphitization of soot even in the absence of laser heating at typical flame temperatures. Recorded experimental LII signal decays and LII-heated peak soot temperature

  5. Numerical modeling of the laser heated solenoid

    Energy Technology Data Exchange (ETDEWEB)

    Chung, C.S.

    1973-01-01

    A numerical model of the interaction of laser radiation with the magnetically confined plasma in an infinitive solenoid was given. An approximate solution which includes the balance of total pressure instead of momentum equation was also developed. Thus, the time step in computing is not bounded by the characteristics given by the Alfven speed. This approximation approach makes the efficient computing of this problem possible. The results of the approximate solution agree very well with those of the exact solution. They have the same final steady state solution.

  6. Group Velocity Measurements in Laser-Heated Capillary Discharge Waveguides for Laser-Plasma Accelerators

    Science.gov (United States)

    Pieronek, C. V.; Daniels, J.; Gonsalves, A. J.; Benedetti, C.; Leemans, W. P.

    2017-10-01

    To date, the most energetic electron beams from laser-plasma accelerators have been produced using gas-filled capillary discharge waveguides, which increase the acceleration length by mitigating diffraction of the driving laser pulse. To reach higher electron beam energies, lower plasma density is required to reduce bunch dephasing. However, confinement of the driver is reduced for lower plasma density, reducing the acceleration length. A laser-heated capillary discharge waveguide, where the discharge is heated by a coaxial laser pulse, was proposed to create a steeper density gradient at lower density. Here the first measurements of group velocity in laser-heated capillary discharges, obtained via spectral interferometry, are presented. Increase of the driver group velocity and reduction in on-axis plasma density by laser-heating are shown. Work supported by the U.S. Dept. of Energy, Office of Science, Office of High Energy Physics, under Contract No. DE-AC02-05CH11231. Additional support by the National Science Foundation under Grant PHY-1415596.

  7. Bio-heat transfer simulation of retinal laser irradiation.

    Science.gov (United States)

    Narasimhan, Arunn; Jha, Kaushal Kumar

    2012-05-01

    Retinopathy is a surgical process in which maladies of the human eye are treated by laser irradiation. A two-dimensional numerical model of the human eye geometry has been developed to investigate transient thermal effects due to laser radiation. In particular, the influence of choroidal pigmentation and that of choroidal blood convection-parameterized as a function of choroidal blood perfusion-are investigated in detail. The Pennes bio-heat transfer equation is invoked as the governing equation, and finite volume formulation is employed in the numerical method. For a 500-μm diameter spot size, laser power of 0.2 W, and 100% absorption of laser radiation in the retinal pigmented epithelium (RPE) region, the peak RPE temperature is observed to be 103 °C at 100 ms of the transient simulation of the laser surgical period. Because of the participation of pigmented layer of choroid in laser absorption, peak temperature is reduced to 94 °C after 100 ms of the laser surgery period. The effect of choroidal blood perfusion on retinal cooling is found to be negligible during transient simulation of retinopathy. A truncated three-dimensional model incorporating multiple laser irradiation of spots is also developed to observe the spatial effect of choroidal blood perfusion and choroidal pigmentation. For a circular array of seven uniformly distributed spots of identical diameter and laser power of 0.2 W, transient temperature evolution using simultaneous and sequential mode of laser surgical process is presented with analysis. Copyright © 2012 John Wiley & Sons, Ltd.

  8. Versatile and Rapid Plasma Heating Device for Steel and Aluminum

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, G.S.

    2006-03-14

    The main objective of the research was to enhance steel and aluminum manufacturing with the development of a new plasma RPD device. During the project (1) plasma devices were manufactured (2) testing for the two metals were carried out and (3) market development strategies were explored. Bayzi Corporation has invented a Rapid Plasma Device (RPD) which produces plasma, comprising of a mixture of ionized gas and free electrons. The ions, when they hit a conducting surface, deposit heat in addition to the convective heat. Two generic models called the RPD-Al and RPD-S have been developed for the aluminum market and the steel market. Aluminum melting rates increased to as high as 12.7 g/s compared to 3 g/s of the current industrial practice. The RPD melting furnace operated at higher energy efficiency of 65% unlike most industrial processes operating in the range of 13 to 50%. The RPD aluminum melting furnace produced environment friendly cleaner melts with less than 1% dross. Dross is the residue in the furnace after the melt is poured out. Cast ingots were extremely clean and shining. Current practices produce dross in the range of 3 to 12%. The RPD furnace uses very low power ~0.2 kWh/Lb to melt aluminum. RPDs operate in one atmosphere using ambient air to produce plasma while the conventional systems use expensive gases like argon, or helium in air-tight chambers. RPDs are easy to operate and do not need intensive capital investment. Narrow beam, as well as wide area plasma have been developed for different applications. An RPD was developed for thermal treatments of steels. Two different applications have been pursued. Industrial air hardening steel knife edges were subjected to plasma beam hardening. Hardness, as measured, indicated uniform distribution without any distortion. The biggest advantage with this method is that the whole part need not be heated in a furnace which will lead to oxidation and distortion. No conventional process will offer localized

  9. High temperature thermographic measurements of laser heated silica

    Energy Technology Data Exchange (ETDEWEB)

    Elhadj, S; Yang, S T; Matthews, M J; Cooke, D J; Bude, J D; Johnson, M; Feit, M; Draggoo, V; Bisson, S E

    2009-11-02

    In situ spatial and temporal surface temperature profiles of CO{sub 2} laser-heated silica were obtained using a long wave infrared (LWIR) HgCdTe camera. Solutions to the linear diffusion equation with volumetric and surface heating are shown to describe the temperature evolution for a range of beam powers, over which the peak surface temperature scales linearly with power. These solutions were used with on-axis steady state and transient experimental temperatures to extract thermal diffusivity and conductivity for a variety of materials, including silica, spinel, sapphire, and lithium fluoride. Experimentally-derived thermal properties agreed well with reported values and, for silica, thermal conductivity and diffusivity are shown to be approximately independent of temperature between 300 and 2800K. While for silica our analysis based on a temperature independent thermal conductivity is shown to be accurate, for other materials studied this treatment yields effective thermal properties that represent reasonable approximations for laser heating. Implementation of a single-wavelength radiation measurement in the semi-transparent regime is generally discussed, and estimates of the apparent temperature deviation from the actual outer surface temperature are also presented. The experimental approach and the simple analysis presented yield surface temperature measurements that can be used to validate more complex physical models, help discriminate dominant heat transport mechanisms, and to predict temperature distribution and evolution during laser-based material processing.

  10. Proton Beam Focusing and Heating in Petawatt Laser-Solid Interactions

    Energy Technology Data Exchange (ETDEWEB)

    Snavely, R A; Gu, P; King, J; Hey, D; Akli, K; Zhang, B B; Freeman, R; Hatchett, S; Key, M H; Koch, J; Langdon, A B; Lasinsky, B; MacKinnon, A; Patel, P; Town, R; Wilks, S; Stephens, R; Tsutsumi, T; Chen, Z; Yabuuchi, T; Kurahashi, T; Sato, T; Adumi, K; Toyama, Y; Zheng, J; Kodama, R; Tanaka, K A; Yamanaka, T

    2003-08-13

    It has recently been demonstrated that femtosecond-laser generated proton beams may be focused. These protons, following expansion of the Debye sheath, emit off the inner concave surface of hemispherical shell targets irradiated at their outer convex pole. The sheath normal expansion produces a rapidly converging proton beam. Such focused proton beams provide a new and powerful means to achieve isochoric heating to high temperatures. They are potentially important for measuring the equation of state of materials at high energy density and may provide an alternative route to fast ignition. We present the first results of proton focusing and heating experiments performed at the Petawatt power level at the Gekko XII Laser Facility at ILE Osaka Japan. Solid density Aluminum slabs are placed in the proton focal region at various lengths. The degree of proton focusing is measured via XUV imaging of Planckian emission of the heated zone. Simultaneous with the XUV measurement a streaked optical imaging technique, HISAK, gave temporal optical emission images of the focal region. Results indicate excellent coupling between the laser-proton conversion and subsequent heating.

  11. Melting and thermal ablation of a silver film induced by femtosecond laser heating: a multiscale modeling approach

    Science.gov (United States)

    Ji, Pengfei; Zhang, Yuwen

    2017-10-01

    The femtosecond laser pulse heating of silver film is investigated by performing quantum mechanics (QM), molecular dynamics (MD), and two-temperature model (TTM) integrated multiscale simulation. The laser excitation dependent electron thermophysical parameters (electron heat capacity, electron thermal conductivity, and effective electron-phonon coupling factor) are determined from ab initio QM calculation, and implemented into TTM description of electron thermal excitation, heat conduction, as well as electron-phonon coupled thermal energy transport. The kinetics of atomic motion is modeled by MD simulation. Energy evolution of excited electron subsystem is described by TTM in continuum. The MD and TTM are coupled by utilizing the effective electron-phonon coupling factor. Laser heating with varying laser fluences is systematically studied to determine the thresholds of homogeneous melting and ablation. The thermal ablation induced by rapid expansion of locally and excessively superheated silver is reported. This paper provides a basis for interpreting the phase-change process induced by laser heating, and facilitates the advancement of femtosecond laser pulse processing of material.

  12. Laser heating of aqueous samples on a micro-optical-electro-mechanical system

    Science.gov (United States)

    Beer, Neil Reginald; Kennedy, Ian

    2013-02-05

    A system of heating a sample on a microchip includes the steps of providing a microchannel flow channel in the microchip; positioning the sample within the microchannel flow channel, providing a laser that directs a laser beam onto the sample for heating the sample; providing the microchannel flow channel with a wall section that receives the laser beam and enables the laser beam to pass through wall section of the microchannel flow channel without being appreciably heated by the laser beam; and providing a carrier fluid in the microchannel flow channel that moves the sample in the microchannel flow channel wherein the carrier fluid is not appreciably heated by the laser beam.

  13. Rapid laser prototyping of valves for microfluidic autonomous systems

    Science.gov (United States)

    Mohammed, M. I.; Abraham, E.; Y Desmulliez, M. P.

    2013-03-01

    Capillary forces in microfluidics provide a simple yet elegant means to direct liquids through flow channel networks. The ability to manipulate the flow in a truly automated manner has proven more problematic. The majority of valves require some form of flow control devices, which are manually, mechanically or electrically driven. Most demonstrated capillary systems have been manufactured by photolithography, which, despite its high precision and repeatability, can be labour intensive, requires a clean room environment and the use of fixed photomasks, limiting thereby the agility of the manufacturing process to readily examine alternative designs. In this paper, we describe a robust and rapid CO2 laser manufacturing process and demonstrate a range of capillary-driven microfluidic valve structures embedded within a microfluidic network. The manufacturing process described allows for advanced control and manipulation of fluids such that flow can be halted, triggered and delayed based on simple geometrical alterations to a given microchannel. The rapid prototyping methodology has been employed with PMMA substrates and a complete device has been created, ready for use, within 2-3 h. We believe that this agile manufacturing process can be applied to produce a range of complex autonomous fluidic platforms and allows subsequent designs to be rapidly explored.

  14. Measurement of heat pump processes induced by laser radiation

    Science.gov (United States)

    Garbuny, M.; Henningsen, T.

    1983-01-01

    A series of experiments was performed in which a suitably tuned CO2 laser, frequency doubled by a Tl3AsSe37 crystal, was brought into resonance with a P-line or two R-lines in the fundamental vibration spectrum of CO. Cooling or heating produced by absorption in CO was measured in a gas-thermometer arrangement. P-line cooling and R-line heating could be demonstrated, measured, and compared. The experiments were continued with CO mixed with N2 added in partial pressures from 9 to 200 Torr. It was found that an efficient collisional resonance energy transfer from CO to N2 existed which increased the cooling effects by one to two orders of magnitude over those in pure CO. Temperature reductions in the order of tens of degrees Kelvin were obtained by a single pulse in the core of the irradiated volume. These measurements followed predicted values rather closely, and it is expected that increase of pulse energies and durations will enhance the heat pump effects. The experiments confirm the feasibility of quasi-isentropic engines which convert laser power into work without the need for heat rejection. Of more immediate potential interest is the possibility of remotely powered heat pumps for cryogenic use, such applications are discussed to the extent possible at the present stage.

  15. Heating of heat-conducting targets by laser pulses with a high-intensity leading spike

    Science.gov (United States)

    Ageev, V. P.; Burdin, S. G.; Konov, V. I.; Uglov, S. A.; Chapliev, N. I.

    1983-04-01

    The results of an analysis of the solution of a one-dimensional heat conduction equation are used to study the specific features of the thermal effects of laser pulses with a leading spike on a target. Simple criteria are obtained for establishing the ability of a pulse to cause a given increase in the target surface temperature during the leading edge of a spike and also during the tail of the laser pulse. A study is made of the influence of the inhomogeneity of the distribution of surface heat sources on the realization of processes characterized by a threshold in respect of the temperature of the irradiated surface. The results obtained are compared with the experimental delay time in the process of initiation of an air breakdown plasma by interaction of CO2 laser pulses with a metal target.

  16. Maxwell-Cattaneo Heat Convection and Thermal Stresses Responses of a Semi-Infinite Medium to High-Speed Laser Heating due to High Speed Laser Heating

    Directory of Open Access Journals (Sweden)

    Abdallah I. A.

    2009-07-01

    Full Text Available Based on Maxwell-Cattaneo convection equation, the thermoelasticity problem is in- vestigated in this paper. The analytic solution of a boundary value problem for a semi- infinite medium with traction free surface heated by a high-speed laser-pulses have Dirac temporal profile is solved. The temperature, the displacement and the stresses distributions are obtained analytically using the Laplace transformation, and discussed at small time duration of the laser pulses. A numerical study for Cu as a target is performed. The results are presented graphically. The obtained results indicate that the small time duration of the laser pulses has no e ect on the finite velocity of the heat con- ductivity, but the behavior of the stress and the displacement distribution are affected due to the pulsed heating process and due to the structure of the governing equations.

  17. Sinterable Ceramic Powders from Laser-Heated Gases.

    Science.gov (United States)

    1988-02-01

    Reactions 25 3. Crystal Structure of Silicon Powders Produced from Laser-Heated Silane 37 IV . Post Synthesis Processing 1. Wetting and Dispersion of Silicon...Society, Session IV , High Temperature Materials Synthesis, Honolulu, Hawaii, Oct. 18-23, 1987 p87-05 IAS S! SIZM CAauiC POWDES: Sy XDS, c ZMUISTICS...ether. carboxylic acid. and aldehyde clases : water is also included.Acrigto William and Goodman.’ a single crystalline sili- The single-crstalline

  18. Laser-ion acceleration via anomalous electron heating

    CERN Document Server

    Yogo, A; Iwata, N; Tosaki, S; Morace, A; Arikawa, Y; Fujioka, S; Nishimura, H; Sagisaka, A; Johzaki, T; Matsuo, K; Kamitsukasa, N; Kojima, S; Nagatomo, H; Nakai, M; Shiraga, H; Murakami, M; Tokita, S; Kawanaka, J; Miyanaga, N; Yamanoi, K; Norimatsu, T; Sakagami, H; Bulanov, S V; Kondo, K; Azechi, H

    2016-01-01

    Using a kilojoule class laser, we demonstrate for the first time that high-contrast picosecond pulses are advantageous for ion acceleration. We show that a laser pulse with optimum duration and a large focal spot accelerates electrons beyond the ponderomotive energy. This anomalous electron heating enables efficient ion acceleration reaching 52 MeV at an intensity of 1.2X10^19 Wcm^-2. The proton energy observed agrees quantitatively with a one-dimensional plasma expansion model newly developed by taking the anomalous heating effect into account. The heating process is confirmed by both measurements with an electron spectrometer and a one-dimensional particle-in-cell simulation. By extending the pulse duration to 6 ps, 5% energy conversion efficiency to protons (50 J out of 1 kJ laser energy) is achieved with an intensity of 10^18-Wcm^-2. The present results are quite encouraging for realizing ion-driven fast ignition and novel ion beamlines.

  19. Heat transfer and fluid flow during laser spot welding of 304 stainless steel

    CERN Document Server

    He, X; Debroy, T

    2003-01-01

    The evolution of temperature and velocity fields during laser spot welding of 304 stainless steel was studied using a transient, heat transfer and fluid flow model based on the solution of the equations of conservation of mass, momentum and energy in the weld pool. The weld pool geometry, weld thermal cycles and various solidification parameters were calculated. The fusion zone geometry, calculated from the transient heat transfer and fluid flow model, was in good agreement with the corresponding experimentally measured values for various welding conditions. Dimensional analysis was used to understand the importance of heat transfer by conduction and convection and the roles of various driving forces for convection in the weld pool. During solidification, the mushy zone grew at a rapid rate and the maximum size of the mushy zone was reached when the pure liquid region vanished. The solidification rate of the mushy zone/liquid interface was shown to increase while the temperature gradient in the liquid zone at...

  20. Impact of two CO(2) laser heatings for damage repairing on fused silica surface.

    Science.gov (United States)

    Cormont, P; Gallais, L; Lamaignère, L; Rullier, J L; Combis, P; Hebert, D

    2010-12-06

    CO(2) laser is an interesting tool to repair defects on silica optics. We studied UV nanosecond laser-induced damage in fused silica after CO(2) laser heating. The localization of damage sites and the laser damage threshold are closely related to stress area in silica induced by heating. By applying a suitable second laser heating, we managed to eliminate the debris issued from redeposited silica and to modify the stress area. As a consequence, a significant increase of laser resistance has been observed. This process offers the possibility to improve damage repairing sufficiently to extend the lifetime of the silica components.

  1. Rapid heating effects on grain-size, texture and magnetic properties ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 34; Issue 7. Rapid heating effects on ... The rapid heating effects on the microstructure, texture and magnetic properties of 3% Si nonoriented electrical steel has been investigated through optical microscopy, X-ray diffraction and Epstein frame. The results show that ...

  2. Effects of particle size and laser wavelength on heating of silver ...

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 87; Issue 2. Effects of ... Nanoparticles, pulsed laser, heating, absorbance. Abstract. Laser energy absorption results in significant heating of metallic nanoparticles and controlling the heating of nanoparticles is one of the essential stages of selective cell targeting.

  3. Analysis of High-Power Diode Laser Heating Effects on HY-80 Steel for Laser Assisted Friction Stir Welding Applications

    Energy Technology Data Exchange (ETDEWEB)

    Wiechec, Maxwell; Baker, Brad; McNelley, Terry; Matthews, Manyalibo; Rubenchik, Alexander; Rotter, Mark; Beach, Ray; Wu, Sheldon

    2017-01-01

    In this research, several conditions of high power diode laser heated HY-80 steel were characterized to determine the viability of using such lasers as a preheating source before friction stir welding in order to reduce frictional forces thereby reducing tool wear and increasing welding speeds. Differences in microstructures within heat affected zones were identified at specific laser powers and traverse speeds. Vickers hardness values were recorded and analyzed to validate the formation of additional martensite in diode laser heated regions of HY-80 steel. Conditions that produced little to no additional martensite were identified and relationships among high power diode laser power, traverse speed, and martensite formation were determined. The development of heat affected zones, change in grain structure, and creation of additional martensite in HY-80 can be prevented through the optimization of laser amperage and transverse speed.

  4. Heat Treatment Development for a Rapidly Solidified Heat Resistant Cast Al-Si Alloy

    Science.gov (United States)

    Kasprzak, W.; Chen, D. L.; Shaha, S. K.

    2013-07-01

    Existing heat treatment standards do not properly define tempers for thin-walled castings that solidified with high solidification rates. Recently emerged casting processes such as vacuum high pressure die casting should not require long solution treatment times due to the fine microstructures arising from rapid solidification rates. The heat treatment studies involving rapidly solidified samples with secondary dendrite arm spacing between 10 and 35 μm were conducted for solution times between 30 min and 9 h and temperatures of 510 and 525 °C and for various aging parameters. The metallurgical analysis revealed that an increase in microstructure refinement could enable a reduction of solution time up to 88%. Solution treatment resulted in the dissolution of Al2Cu and Al5Mg8Si6Cu2, while Fe- and TiZrV-based phases remained partially in the microstructure. The highest strength of approximately 351 ± 9.7 and 309 ± 3.4 MPa for the UTS and YS, respectively, was achieved for a 2-step solution treatment at 510 and 525 °C in the T6 peak aging conditions, i.e., 150 °C for 100 h. The T6 temper did not yield dimensionally stable microstructure since exceeding 250 °C during in-service operation could result in phase transformation corresponding to the over-aging reaction. The microstructure refinement had a statistically stronger effect on the alloy strength than the increase in solutionizing time. Additionally, thermal analysis and dilatometer results were presented to assess the dissolution of phases during solution treatment, aging kinetics as well as dimensional stability.

  5. Rapidly tuning miniature transversely excited atmospheric-pressure CO2 laser.

    Science.gov (United States)

    Qu, Yanchen; Ren, Deming; Hu, Xiaoyong; Liu, Fengmei; Zhao, Jingshan

    2002-08-20

    An experimental study of a rapidly tuning miniature transversely excited atmospheric-pressure CO2 laser is reported. To rapidly shift laser wavelengths over selected transitions in the 9-11 microm wavelength region, we have utilized a high-frequency stepping motor and a diffraction grating. The laser is highly automated with a monolithic microprocessor controlled laser line selection. For the achievement of stable laser output, a system of laser excitation with a voltage of 10 kV, providing effective surface corona preionization and allowing one to work at various gas pressures, is utilized. Laser operation at 59 emission lines of the CO2 molecule rotational transition is obtained and at 51 lines, the pulse energy of laser radiation exceeds 30 mJ. The system can be tuned between two different rotational lines spanning the wavelength range from 9.2 to 10.8 microm within 10 ms.

  6. Numerical investigation of vessel heating using a copper vapor laser and a pulsed dye laser in treating vascular skin lesions

    Science.gov (United States)

    Pushkareva, A. E.; Ponomarev, I. V.; Isaev, A. A.; Klyuchareva, S. V.

    2018-02-01

    A computer simulation technique was employed to study the selective heating of a tissue vessel using emission from a pulsed copper vapor laser and a pulsed dye laser. The depth and size of vessels that could be selectively and safely removed were determined for the lasers under examination.

  7. Laser Heating of the Core-Shell Nanowires

    Science.gov (United States)

    Astefanoaei, Iordana; Dumitru, Ioan; Stancu, Alexandru

    2016-12-01

    The induced thermal stress in a heating process is an important parameter to be known and controlled in the magnetization process of core-shell nanowires. This paper analyses the stress produced by a laser heating source placed at one end of a core-shell type structure. The thermal field was computed with the non-Fourier heat transport equation using a finite element method (FEM) implemented in Comsol Multiphysics. The internal stresses are essentially due to thermal gradients and different expansion characteristics of core and shell materials. The stress values were computed using the thermo elastic formalism and are depending on the laser beam parameters (spot size, power etc.) and system characteristics (dimensions, thermal characteristics). Stresses in the GPa range were estimated and consequently we find that the magnetic state of the system can be influenced significantly. A shell material as the glass which is a good thermal insulator induces in the magnetic core, the smaller stresses and consequently the smaller magnetoelastic energy. These results lead to a better understanding of the switching process in the magnetic materials.

  8. Combined laser ultrasonics, laser heating, and Raman scattering in diamond anvil cell system

    Science.gov (United States)

    Zinin, Pavel V.; Prakapenka, Vitali B.; Burgess, Katherine; Odake, Shoko; Chigarev, Nikolay; Sharma, Shiv K.

    2016-12-01

    We developed a multi-functional in situ measurement system under high pressure equipped with a laser ultrasonics (LU) system, Raman device, and laser heating system (LU-LH) in a diamond anvil cell (DAC). The system consists of four components: (1) a LU-DAC system (probe and pump lasers, photodetector, and oscilloscope) and DAC; (2) a fiber laser, which is designed to allow precise control of the total power in the range from 2 to 100 W by changing the diode current, for heating samples; (3) a spectrometer for measuring the temperature of the sample (using black body radiation), fluorescence spectrum (spectrum of the ruby for pressure measurement), and Raman scattering measurements inside a DAC under high pressure and high temperature (HPHT) conditions; and (4) an optical system to focus laser beams on the sample and image it in the DAC. The system is unique and allows us to do the following: (a) measure the shear and longitudinal velocities of non-transparent materials under HPHT; (b) measure temperature in a DAC under HPHT conditions using Planck's law; (c) measure pressure in a DAC using a Raman signal; and (d) measure acoustical properties of small flat specimens removed from the DAC after HPHT treatment. In this report, we demonstrate that the LU-LH-DAC system allows measurements of velocities of the skimming waves in iron at 2580 K and 22 GPa.

  9. Study, optimization, and design of a laser heat engine. [for satellite applications

    Science.gov (United States)

    Taussig, R. T.; Cassady, P. E.; Zumdieck, J. F.

    1978-01-01

    Laser heat engine concepts, proposed for satellite applications, are analyzed to determine which engine concept best meets the requirements of high efficiency (50 percent or better), continuous operation in space using near-term technology. The analysis of laser heat engines includes the thermodynamic cycles, engine design, laser power sources, collector/concentrator optics, receiving windows, absorbers, working fluids, electricity generation, and heat rejection. Specific engine concepts, optimized according to thermal efficiency, are rated by their technological availability and scaling to higher powers. A near-term experimental demonstration of the laser heat engine concept appears feasible utilizing an Otto cycle powered by CO2 laser radiation coupled into the engine through a diamond window. Higher cycle temperatures, higher efficiencies, and scalability to larger sizes appear to be achievable from a laser heat engine design based on the Brayton cycle and powered by a CO laser.

  10. Investigation of electron heating in laser-plasma interaction

    Directory of Open Access Journals (Sweden)

    A Parvazian

    2013-03-01

    Full Text Available  In this paper, stimulated Raman scattering (SRS and electron heating in laser plasma propagating along the plasma fusion is investigated by particle-in cell simulation. Applying an external magnetic field to plasma, production of whistler waves and electron heating associated with whistler waves in the direction perpendicular to external magnetic field was observed in this simulation. The plasma waves with low phase velocities, generated in backward-SRS and dominateing initially in time and space, accelerated the backward electrons by trapping them. Then these electrons promoted to higher energies by the forward-SRS plasma waves with high phase velocities. This tow-stage electron acceleration is more efficient due to the coexistence of these two instabilities.

  11. Effect of soft-core potentials on inverse bremsstrahlung heating during laser matter interactions

    Science.gov (United States)

    Pandit, Rishi R.; Sentoku, Yasuhiko; Becker, Valerie R.; Barrington, Kasey; Thurston, Jeremy; Cheatham, Jonathan; Ramunno, Lora; Ackad, Edward

    2017-07-01

    Inverse bremsstrahlung heating (IBH) is studied by using scattering theory for the interaction of intense lasers with matter using soft-core potentials. This involves three different kinds of interactions: (i) the interaction of the electrons with the external laser field, (ii) the electron-ion interaction, and (iii) the electron-electron interaction. In the interaction of rare-gas clusters with ultrashort laser pulses, nano-plasmas with high densities are created. A new scaling for the differential cross-section and the rate of energy absorption via IBH is derived which depends on the external laser field as well as electric field due to the other particles. When the particles are treated as charge distributions, the electric fields due to the other particles depend on a parameter of the non-Coulombic soft-core field, the potential depth, often used to avoid the Coulomb singularity. Thus, the rate of IBH also depends on the potential depth. Calculations are performed for electrons in a range of wavelength regimes from the vacuum ultraviolet to the mid-infrared. The rate of energy absorption via IBH is found to increase rapidly with increases in the potential depth and then quickly becomes mostly saturated at the Coulomb value for greater depths. The rate of energy absorption via IBH is found to be non-linear with laser intensities. The differential cross-section as well as the rate of energy absorption of IBH is found to increase with increases in laser wavelength. Finally, lower laser intensities saturate more slowly, requiring a larger potential depth to saturate.

  12. Melt Flow and Heat Transfer in Laser Drilling

    CERN Document Server

    Yang, Youqing; Zhang, Yuwen

    2016-01-01

    During the laser drilling process the recoil pressure drives melt flow and affects the heat transfer and material removal rate. To get a more realistic picture of the melt flow, a series of differential equations are formulated here that govern the process from pre-heating to melting and evaporation. In particular, the Navier-Stokes equation governing the melt flow is solved with the use of the boundary layer theory and integral methods. Heat conduction in solid is investigated by using the classical method with the corrections that reflect the change in boundary condition from the constant heat flux to Stefan condition. The dependence of saturation temperature on the vapor pressure is taken into account by using the Clausius-Clapeyron equation. Both constantly rising radial velocity profiles and rising-fall velocity profiles are considered. The proposed approach is compared with existing ones. In spite of the assumed varying velocity profiles, the proposed model predicts that the drilling hole profiles are v...

  13. Thermal pressure in the laser-heated diamond anvil cell

    Science.gov (United States)

    Heinz, Dion L.

    1990-07-01

    Estimation of the thermal elastic effect is necessary for the calibration of the pressure and temperature conditions during laser-heated diamond anvil cell experiments, since above 800K, the standard technique of using ruby florescence to measure pressure fails. Continuum calculations based upon the thermoelastic equations for an elastic medium were used to estimate the thermal pressure resulting from a radially symmetric temperature gradient in an elastic sphere with zero displacement on its surface. This calculation corresponds to the thermal pressure generated in a laser-heated diamond anvil cell sample that is compressed without a pressure medium. This solution must fall between circumstances where the sample is held at constant pressure and where the sample is held at constant volume. It is shown here that the thermal pressure in an elastic medium with a Gaussian temperature gradient is approximately 40-60% of the thermodynamic value of the thermal pressure in a material raised to some constant temperature with the volume constrained to be constant. Even though the thermal pressure correction can be significant in terms of the total pressure that the sample experiences, these calculations indicate that the correction can be estimated to approximately 10%.

  14. Plasma column development in the CO2 laser-heated solenoid

    Science.gov (United States)

    Tighe, W.; Offenberger, A. A.; Capjack, C. E.

    1987-08-01

    Axial and radial plasma dynamics in the CO2 laser-heated solenoid have been studied experimentally and numerically. The axial behavior is found to be well described by a self-regulated bleaching wave model. The radial expansion is found to be strongly dependent on the focusing ratio of the input laser beam. With a fast focus ( f/5), the early radial expansion rate is twice that found with a slower focusing arrangement ( f/15). The faster focusing ratio also results in a significantly wider plasma column. On the other hand, no significant dependence of f/♯ on the axial propagation was found. A finite ionization time and the rapid formation of a density minimum on axis are observed and verify earlier experimental results. Detailed comparisons are made with a 2-D magnetohydrodynamic (MHD) and laser propagation code. The axial and radial plasma behavior and, in particular, the dependence of the radial behavior on the focal ratio of the laser are reasonably well supported by the simulation results. Computational results are also in good agreement with experimental measurements of temperature and density using stimulated scattering (Brillouin, Raman) and interferometry diagnostic techniques.

  15. Rapid IV Versus Oral Rehydration: Responses to Subsequent Exercise Heat Stress

    National Research Council Canada - National Science Library

    Kenefick, Robert W; O'Moore, Kathleen M; Mahood, Nicholas V; Castellani, John W

    2006-01-01

    This study sought to determine the effect of rapid intravenous (IV) versus oral (ORAL) rehydration immediately after dehydration, on cardiovascular, thermoregulatory, and perceptual responses during subsequent exercise in the heat.

  16. Rapid shift in thermal resistance between generations through maternal heat exposure

    NARCIS (Netherlands)

    Zizzari, Z.V.; Ellers, J.

    2014-01-01

    Given the current rapid climate change, understanding the mechanisms underlying heat tolerance and its plasticity is an important goal of global change biology. Soil fauna communities are especially vulnerable because of their limited dispersal ability. It is generally recognized that

  17. The Effective Fracture Toughness of Aluminum at Rapid Heating Rates.

    Science.gov (United States)

    1987-12-01

    Load (lb) y Load at Yield (lb) 1 Plate thickness N Number of Fatigue Cucles n Ramberg - Osgood exponent for true plastic tensile strain S P Laser power on...l Etftl tun-i ( [I ___nlhfu t _(_t )__l] C10) n + l y toa t I t u t E t where n - the Ramberg - Osgood exponent for true plastic tensile v strain...n htpuatu (at n+l E tf tl ,tu, n uhu n+l [ (-) hf u -0tu tut t where n - the Ramberg - Osgood exponent for true plastic tensile strain atpu - true

  18. Feasibility of computed tomography based thermometry during interstitial laser heating in bovine liver

    NARCIS (Netherlands)

    Pandeya, G. D.; Klaessens, J. H. G. M.; Greuter, M. J. W.; Schmidt, B.; Flohr, T.; van Hillegersberg, R.; Oudkerk, M.

    To assess the feasibility of computed tomography (CT) based thermometry during interstitial laser heating in the bovine liver. Four freshly exercised cylindrical blocks of bovine tissue were heated using a continuous laser of Nd:YAG (wavelength: 1064 nm, active length: 30 mm, power: 10-30 W). All

  19. Rapid Solidification: Selective Laser Melting of AlSi10Mg

    Science.gov (United States)

    Tang, Ming; Pistorius, P. Chris; Narra, Sneha; Beuth, Jack L.

    2016-03-01

    Rapid movement of the melt pool (at a speed around 1 m/s) in selective laser melting of metal powder directly implies rapid solidification. In this work, the length scale of the as-built microstructure of parts built with the alloy AlSi10Mg was measured and compared with the well-known relationship between cell size and cooling rate. Cooling rates during solidification were estimated using the Rosenthal equation. It was found that the solidification structure is the expected cellular combination of silicon with α-aluminum. The dependence of measured cell spacing on calculated cooling rate follows the well-established relationship for aluminum alloys. The implication is that cell spacing can be manipulated by changing the heat input. Microscopy of polished sections through particles of the metal powder used to build the parts showed that the particles have a dendritic-eutectic structure; the dendrite arm spacings in metal powder particles of different diameters were measured and also agree with literature correlations, showing the expected increase in secondary dendrite arm spacing with increasing particle diameter.

  20. Transient Response to Rapid Cooling of a Stainless Steel Sodium Heat Pipe

    Science.gov (United States)

    Mireles, Omar R.; Houts, Michael G.

    2011-01-01

    Compact fission power systems are under consideration for use in long duration space exploration missions. Power demands on the order of 500 W, to 5 kW, will be required for up to 15 years of continuous service. One such small reactor design consists of a fast spectrum reactor cooled with an array of in-core alkali metal heat pipes coupled to thermoelectric or Stirling power conversion systems. Heat pipes advantageous attributes include a simplistic design, lack of moving parts, and well understood behavior. Concerns over reactor transients induced by heat pipe instability as a function of extreme thermal transients require experimental investigations. One particular concern is rapid cooling of the heat pipe condenser that would propagate to cool the evaporator. Rapid cooling of the reactor core beyond acceptable design limits could possibly induce unintended reactor control issues. This paper discusses a series of experimental demonstrations where a heat pipe operating at near prototypic conditions experienced rapid cooling of the condenser. The condenser section of a stainless steel sodium heat pipe was enclosed within a heat exchanger. The heat pipe - heat exchanger assembly was housed within a vacuum chamber held at a pressure of 50 Torr of helium. The heat pipe was brought to steady state operating conditions using graphite resistance heaters then cooled by a high flow of gaseous nitrogen through the heat exchanger. Subsequent thermal transient behavior was characterized by performing an energy balance using temperature, pressure and flow rate data obtained throughout the tests. Results indicate the degree of temperature change that results from a rapid cooling scenario will not significantly influence thermal stability of an operating heat pipe, even under extreme condenser cooling conditions.

  1. Laser heating of finite two-dimensional dust clusters: A. Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Schablinski, Jan; Block, Dietmar; Piel, Alexander [Institut fuer Experimentelle und Angewandte Physik, Christian-Albrechts-Universitaet zu Kiel, 24098 Kiel (Germany); Melzer, Andre [Institut fuer Physik, Ernst-Moritz-Arndt-Universitaet Greifswald, 17487 Greifswald (Germany); Thomsen, Hauke; Kaehlert, Hanno; Bonitz, Michael [Institut fuer Theoretische Physik und Astrophysik, Christian-Albrechts-Universitaet zu Kiel, 24098 Kiel (Germany)

    2012-01-15

    Laser manipulation allows to control the kinetic particle temperature in dusty plasmas. Different methods of laser heating for plasma crystals are benchmarked experimentally. The methods are analyzed with respect to homogeneity and isotropy in a spatial, temporal, and statistical sense. It is shown that it is possible to achieve particle dynamics very close to thermal equilibrium and that laser heating methods allow for a detailed study of phase transitions in finite size systems.

  2. Self-consistent viscous heating of rapidly compressed turbulence

    Science.gov (United States)

    Campos, Alejandro; Morgan, Brandon; Olson, Britton; Greenough, Jeffrey

    2016-11-01

    Given turbulence subjected to infinitely rapid deformations, linear terms representing interactions between the mean flow and the turbulence dictate the flow evolution, whereas non-linear terms corresponding to turbulence-turbulence interactions are safely ignored. For rapidly deformed flows where the turbulence Reynolds number is not sufficiently large, viscous effects can't be neglected and tend to play a prominent role, as shown in Davidovits & Fisch (2016). For such a case, the rapid increase of viscosity in a plasma-as compared to the weaker scaling of viscosity in a fluid-leads to the sudden viscous dissipation of turbulent kinetic energy. As described in Davidovits & Fisch, increases in temperature caused by the direct compression of the plasma drive sufficiently large values of viscosity. We report on numerical simulations of turbulence where the increase in temperature is the result of both the direct compression (an inviscid mechanism) and the self-consistent viscous transfer of energy from the turbulent scales towards the thermal energy. A comparison between implicit large-eddy simulations against well-resolved direct numerical simulations is included to asses the effect of the numerical and subgrid-scale dissipation on the self-consistent viscous energy transfer. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  3. Analysis of the heat affected zone in CO2 laser cutting of stainless steel

    Directory of Open Access Journals (Sweden)

    Madić Miloš J.

    2012-01-01

    Full Text Available This paper presents an investigation into the effect of the laser cutting parameters on the heat affected zone in CO2 laser cutting of AISI 304 stainless steel. The mathematical model for the heat affected zone was expressed as a function of the laser cutting parameters such as the laser power, cutting speed, assist gas pressure and focus position using the artificial neural network. To obtain experimental database for the artificial neural network training, laser cutting experiment was planned as per Taguchi’s L27 orthogonal array with three levels for each of the cutting parameter. Using the 27 experimental data sets, the artificial neural network was trained with gradient descent with momentum algorithm and the average absolute percentage error was 2.33%. The testing accuracy was then verified with 6 extra experimental data sets and the average predicting error was 6.46%. Statistically assessed as adequate, the artificial neural network model was then used to investigate the effect of the laser cutting parameters on the heat affected zone. To analyze the main and interaction effect of the laser cutting parameters on the heat affected zone, 2-D and 3-D plots were generated. The analysis revealed that the cutting speed had maximum influence on the heat affected zone followed by the laser power, focus position and assist gas pressure. Finally, using the Monte Carlo method the optimal laser cutting parameter values that minimize the heat affected zone were identified.

  4. Numerical analysis of thermal deformation in laser beam heating of a steel plate

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Chao; Kim, Yong-Rae; Kim, Jae-Woong [Yeungnam University, Kyongsan (Korea, Republic of)

    2017-05-15

    Line heating is a widely used process for plate forming or thermal straightening. Flame heating and induction heating are the traditional heating processes used by industry for line heating. However, these two heating processes are ineffective when used on small steel plates. Thus, the laser beam heating with various power profiles were carried out in this study. A comparison of numerical simulation results and experimental results found a significant difference in the thermal deformation when apply a different power profile of laser beam heating. The one-sinusoid power profile produced largest thermal deformation in this study. The laser beam heating process was simulated by established a combined heat source model, and simulated results were compared with experimental results to confirm the model’s accuracy. The mechanism of thermal deformation was investigated and the effects of model parameters were studied intensively with the finite element method. Thermal deformation was found to have a significant relationship with the amount of central zone plastic deformation. Scientists and engineers could use this study’s verified model to select appropriate parameters in laser beam heating process. Moreover, by using the developed laser beam model, the analysis of welding residual stress or hardness could also be investigated from a power profile point of view.

  5. Firearm suppressor having enhanced thermal management for rapid heat dissipation

    Science.gov (United States)

    Moss, William C.; Anderson, Andrew T.

    2014-08-19

    A suppressor is disclosed for use with a weapon having a barrel through which a bullet is fired. The suppressor has an inner portion having a bore extending coaxially therethrough. The inner portion is adapted to be secured to a distal end of the barrel. A plurality of axial flow segments project radially from the inner portion and form axial flow paths through which expanding propellant gasses discharged from the barrel flow through. The axial flow segments have radially extending wall portions that define sections which may be filled with thermally conductive material, which in one example is a thermally conductive foam. The conductive foam helps to dissipate heat deposited within the suppressor during firing of the weapon.

  6. Rapid die manufacturing using direct laser metal deposition

    CSIR Research Space (South Africa)

    Pereira, MFVT

    2009-01-01

    Full Text Available This paper highlights the work undertaken at the CSIR on the issue of rapid die manufacturing through the application and evaluation of a rapid prototyping technique and coating technologies applied to die components of a high pressure casting die...

  7. Army Solid State Laser Program: Design, Operation, and Mission Analysis for a Heat-Capacity Laser

    Energy Technology Data Exchange (ETDEWEB)

    Dane, C B; Flath, L; Rotter, M; Fochs, S; Brase, J; Bretney, K

    2001-05-18

    Solid-state lasers have held great promise for the generation of high-average-power, high-quality output beams for a number of decades. However, the inherent difficulty of scaling the active solid-state gain media while continuing to provide efficient cooling has limited demonstrated powers to <5kW. Even at the maximum demonstrated average powers, the output is most often delivered as continuous wave (CW) or as small energy pulses at high pulse repetition frequency (PRF) and the beam divergence is typically >10X the diffraction limit. Challenges posed by optical distortions and depolarization arising from internal temperature gradients in the gain medium of a continuously cooled system are only increased for laser designs that would attempt to deliver the high average power in the form of high energy pulses (>25J) from a single coherent optical aperture. Although demonstrated phase-locking of multiple laser apertures may hold significant promise for the future scaling of solid-state laser systems,1 the continuing need for additional technical development and innovation coupled with the anticipated complexity of these systems effectively limits this approach for near-term multi-kW laser operation outside of a laboratory setting. We have developed and demonstrated a new operational mode for solid-state laser systems in which the cooling of the gain medium is separated in time from the lasing cycle. In ''heat-capacity'' operation, no cooling takes place during lasing. The gain medium is pumped very uniformly and the waste heat from the excitation process is stored in the solid-state gain medium. By depositing the heat on time scales that are short compared to thermal diffusion across the optical aperture, very high average power operation is possible while maintaining low optical distortions. After a lasing cycle, aggressive cooling can then take place in the absence of lasing, limited only by the fracture limit of the solid-state medium. This mode

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

    Indian Academy of Sciences (India)

    It is important to study the behaviour of nuclear fuels under transient heating conditions from the point of view of nuclear safety. To simulate the transient heating conditions occurring in the known reactor accidents like loss of coolant accident (LOCA) and reactivity initiated accident (RIA), a laser pulse heating system is under ...

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

    Indian Academy of Sciences (India)

    Abstract. It is important to study the behaviour of nuclear fuels under transient heating conditions from the point of view of nuclear safety. To simulate the transient heating conditions occurring in the known reactor accidents like loss of coolant accident (LOCA) and reactivity initiated accident (RIA), a laser pulse heating ...

  10. Rapid prototyping of polymeric microstructures with a UV laser

    DEFF Research Database (Denmark)

    Jensen, Martin F.; McCormack, John E.; Helbo, Bjarne

    2003-01-01

    ion implantation of the master tool to prolong the lifetime has also been investigated. For injection moulding, where the pressure and temperature is higher than in hot embossing a positive laser ablated Acrylonitrile-butadien-styrene co-polymer (ABS) structure was used, which subsequently has been...

  11. Subsampling phase retrieval for rapid thermal measurements of heated microstructures.

    Science.gov (United States)

    Taylor, Lucas N; Talghader, Joseph J

    2016-07-15

    A subsampling technique for real-time phase retrieval of high-speed thermal signals is demonstrated with heated metal lines such as those found in microelectronic interconnects. The thermal signals were produced by applying a current through aluminum resistors deposited on soda-lime-silica glass, and the resulting refractive index changes were measured using a Mach-Zehnder interferometer with a microscope objective and high-speed camera. The temperatures of the resistors were measured both by the phase-retrieval method and by monitoring the resistance of the aluminum lines. The method used to analyze the phase is at least 60× faster than the state of the art but it maintains a small spatial phase noise of 16 nm, remaining comparable to the state of the art. For slowly varying signals, the system is able to perform absolute phase measurements over time, distinguishing temperature changes as small as 2 K. With angular scanning or structured illumination improvements, the system could also perform fast thermal tomography.

  12. Nanoscale Structural and Mechanical Analysis of Bacillus anthracis Spores Inactivated with Rapid Dry Heating

    Science.gov (United States)

    Felker, Daniel L.; Burggraf, Larry W.

    2014-01-01

    Effective killing of Bacillus anthracis spores is of paramount importance to antibioterrorism, food safety, environmental protection, and the medical device industry. Thus, a deeper understanding of the mechanisms of spore resistance and inactivation is highly desired for developing new strategies or improving the known methods for spore destruction. Previous studies have shown that spore inactivation mechanisms differ considerably depending upon the killing agents, such as heat (wet heat, dry heat), UV, ionizing radiation, and chemicals. It is believed that wet heat kills spores by inactivating critical enzymes, while dry heat kills spores by damaging their DNA. Many studies have focused on the biochemical aspects of spore inactivation by dry heat; few have investigated structural damages and changes in spore mechanical properties. In this study, we have inactivated Bacillus anthracis spores with rapid dry heating and performed nanoscale topographical and mechanical analysis of inactivated spores using atomic force microscopy (AFM). Our results revealed significant changes in spore morphology and nanomechanical properties after heat inactivation. In addition, we also found that these changes were different under different heating conditions that produced similar inactivation probabilities (high temperature for short exposure time versus low temperature for long exposure time). We attributed the differences to the differential thermal and mechanical stresses in the spore. The buildup of internal thermal and mechanical stresses may become prominent only in ultrafast, high-temperature heat inactivation when the experimental timescale is too short for heat-generated vapor to efficiently escape from the spore. Our results thus provide direct, visual evidences of the importance of thermal stresses and heat and mass transfer to spore inactivation by very rapid dry heating. PMID:24375142

  13. Rapid Prototyping — A Tool for Presenting 3-Dimensional Digital Models Produced by Terrestrial Laser Scanning

    Directory of Open Access Journals (Sweden)

    Juho-Pekka Virtanen

    2014-07-01

    Full Text Available Rapid prototyping has received considerable interest with the introduction of affordable rapid prototyping machines. These machines can be used to manufacture physical models from three-dimensional digital mesh models. In this paper, we compare the results obtained with a new, affordable, rapid prototyping machine, and a traditional professional machine. Two separate data sets are used for this, both of which were acquired using terrestrial laser scanning. Both of the machines were able to produce complex and highly detailed geometries in plastic material from models based on terrestrial laser scanning. The dimensional accuracies and detail levels of the machines were comparable, and the physical artifacts caused by the fused deposition modeling (FDM technique used in the rapid prototyping machines could be found in both models. The accuracy of terrestrial laser scanning exceeded the requirements for manufacturing physical models of large statues and building segments at a 1:40 scale.

  14. Study on VCSEL laser heating chip in nuclear magnetic resonance gyroscope

    Science.gov (United States)

    Liang, Xiaoyang; Zhou, Binquan; Wu, Wenfeng; Jia, Yuchen; Wang, Jing

    2017-10-01

    In recent years, atomic gyroscope has become an important direction of inertial navigation. Nuclear magnetic resonance gyroscope has a stronger advantage in the miniaturization of the size. In atomic gyroscope, the lasers are indispensable devices which has an important effect on the improvement of the gyroscope performance. The frequency stability of the VCSEL lasers requires high precision control of temperature. However, the heating current of the laser will definitely bring in the magnetic field, and the sensitive device, alkali vapor cell, is very sensitive to the magnetic field, so that the metal pattern of the heating chip should be designed ingeniously to eliminate the magnetic field introduced by the heating current. In this paper, a heating chip was fabricated by MEMS process, i.e. depositing platinum on semiconductor substrates. Platinum has long been considered as a good resistance material used for measuring temperature The VCSEL laser chip is fixed in the center of the heating chip. The thermometer resistor measures the temperature of the heating chip, which can be considered as the same temperature of the VCSEL laser chip, by turning the temperature signal into voltage signal. The FPGA chip is used as a micro controller, and combined with PID control algorithm constitute a closed loop control circuit. The voltage applied to the heating resistor wire is modified to achieve the temperature control of the VCSEL laser. In this way, the laser frequency can be controlled stably and easily. Ultimately, the temperature stability can be achieved better than 100mK.

  15. Structural stability of hydrogenated amorphous carbon overcoats used in heat-assisted magnetic recording investigated by rapid thermal annealing

    KAUST Repository

    Wang, N.

    2013-01-01

    Ultrathin amorphous carbon (a-C) films are extensively used as protective overcoats of magnetic recording media. Increasing demands for even higher storage densities have necessitated the development of new storage technologies, such as heat-assisted magnetic recording (HAMR), which uses laser-assisted heating to record data on high-stability media that can store single bits in extremely small areas (∼1 Tbit/in.2). Because HAMR relies on locally changing the coercivity of the magnetic medium by raising the temperature above the Curie temperature for data to be stored by the magnetic write field, it raises a concern about the structural stability of the ultrathin a-C film. In this study, rapid thermal annealing (RTA) experiments were performed to examine the thermal stability of ultrathin hydrogenated amorphous carbon (a-C:H) films deposited by plasma-enhanced chemical vapor deposition. Structural changes in the a-C:H films caused by RTA were investigated by x-ray photoelectron spectroscopy, Raman spectroscopy, x-ray reflectivity, and conductive atomic force microscopy. The results show that the films exhibit thermal stability up to a maximum temperature in the range of 400-450 °C. Heating above this critical temperature leads to hydrogen depletion and sp 2 clustering. The critical temperature determined by the results of this study represents an upper bound of the temperature rise due to laser heating in HAMR hard-disk drives and the Curie temperature of magnetic materials used in HAMR hard disks. © 2013 American Institute of Physics.

  16. Rapid microfabrication of transparent materials using filamented femtosecond laser pulses

    Science.gov (United States)

    Butkus, S.; Gaižauskas, E.; Paipulas, D.; Viburys, Ž.; Kaškelyė, D.; Barkauskas, M.; Alesenkov, A.; Sirutkaitis, V.

    2014-01-01

    Microfabrication of transparent materials using femtosecond laser pulses has showed good potential towards industrial application. Maintaining pulse energies exceeding the critical self-focusing threshold by more than 100-fold produced filaments that were used for micromachining purposes. This article demonstrates two different micromachining techniques using femtosecond filaments generated in different transparent media (water and glass). The stated micromachining techniques are cutting and welding of transparent samples. In addition, cutting and drilling experiments were backed by theoretical modelling giving a deeper insight into the whole process. We demonstrate cut-out holes in soda-lime glass having thickness up to 1 mm and aspect ratios close to 20, moreover, the fabrication time is of the order of tens of seconds, in addition, grooves and holes were fabricated in hardened 1.1 mm thick glass (Corning Gorilla glass). Glass welding was made possible and welded samples were achieved after several seconds of laser fabrication.

  17. Energy coupling and plume dynamics during high power laser heating of metals

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, S. [Univ. of California, Berkeley, CA (United States). Dept. of Mechanical Engineering]|[Lawrence Berkeley National Lab., CA (United States). Environmental Energy Technologies Div.

    1997-05-01

    High power laser heating of metals was studied utilizing experimental and numerical methods with an emphasis on the laser energy coupling with a target and on the dynamics of the laser generated vapor flow. Rigorous theoretical modeling of the heating, melting, and evaporation of metals due to laser radiation with a power density below the plasma shielding threshold was carried out. Experimentally, the probe beam deflection technique was utilized to measure the propagation of a laser induced shock wave. The effects of a cylindrical cavity in a metal surface on the laser energy coupling with a solid were investigated utilizing photothermal deflection measurements. A numerical calculation of target temperature and photothermal deflection was performed to compare with the measured results. Reflection of the heating laser beam inside the cavity was found to increase the photothermal deflection amplitude significantly and to enhance the overall energy coupling between a heating laser beam and a solid. Next, unsteady vaporization of metals due to nanosecond pulsed laser heating with an ambient gas at finite pressure was analyzed with a one dimensional thermal evaporation model for target heating and one dimensional compressible flow equations for inviscid fluid for the vapor flow. Lastly, the propagation of a shock wave during excimer laser heating of aluminum was measured with the probe beam deflection technique. The transit time of the shock wave was measured at the elevation of the probe beam above the target surface; these results were compared with the predicted behavior using ideal blast wave theory. The propagation of a gaseous material plume was also observed from the deflection of the probe beam at later times.

  18. A Novel Laser Direct Writing System Integrated with A&F XXY Alignment Platform for Rapid Fabrication of Flexible Electronics

    Directory of Open Access Journals (Sweden)

    Yi-Kai Liu

    2015-05-01

    Full Text Available In this study, a novel laser direct synthesis and pattering technology is applied in conjunction with an A&F XXY alignment platform to rapidly fabricate flexible conductors on a polymer substrate (polyimide film with designated patterns. In the process, a focused continuous wave green laser was focused onto the polymer substrate that is mounted and directed using the XXY alignment platform. The focused laser energy absorbed by the polymer substrate is used to heat the transparent and particle-free reactive silver ink on the polymer substrate surface. With appropriate programing of the XXY alignment platform motion to control the laser scanning parameters, silver patterns with good electrical conductivity were successfully obtained. This technology can be operated directly at atmospheric pressure and room temperature. It does not require the use of vacuum chamber, oven and photo-mask, etc. Therefore, this novel technology and system offers a new approach to the cost-effective and green fabrication for flexible electronics. The compact size and excellent stability of the XXY alignment platform make the fabrication system even more competitive. In particular, the programmable small radius plane rotation function of the XXY alignment platform provides flexibility in the pattern design with turnings while keeps the uniformity of the resulted micro metal lines.

  19. Welding of Semiconductor Nanowires by Coupling Laser-Induced Peening and Localized Heating

    Science.gov (United States)

    Rickey, Kelly M.; Nian, Qiong; Zhang, Genqiang; Chen, Liangliang; Suslov, Sergey; Bhat, S. Venkataprasad; Wu, Yue; Cheng, Gary J.; Ruan, Xiulin

    2015-11-01

    We demonstrate that laser peening coupled with sintering of CdTe nanowire films substantially enhances film quality and charge transfer while largely maintaining basic particle morphology. During the laser peening phase, a shockwave is used to compress the film. Laser sintering comprises the second step, where a nanosecond pulse laser beam welds the nanowires. Microstructure, morphology, material content, and electrical conductivities of the films are characterized before and after treatment. The morphology results show that laser peening can decrease porosity and bring nanowires into contact, and pulsed laser heating fuses those contacts. Multiphysics simulations coupling electromagnetic and heat transfer modules demonstrate that during pulsed laser heating, local EM field enhancement is generated specifically around the contact areas between two semiconductor nanowires, indicating localized heating. The characterization results indicate that solely laser peening or sintering can only moderately improve the thin film quality; however, when coupled together as laser peen sintering (LPS), the electrical conductivity enhancement is dramatic. LPS can decrease resistivity up to a factor of ~10,000, resulting in values on the order of ~105 Ω-cm in some cases, which is comparable to CdTe thin films. Our work demonstrates that LPS is an effective processing method to obtain high-quality semiconductor nanocrystal films.

  20. An inductively heated hot cavity catcher laser ion source

    CERN Document Server

    Reponen, M; Pohjalainen, I; Rothe, S; Savonen, M; Sonnenschein, V; Voss, A

    2015-01-01

    An inductively heated hot cavity catcher has been constructed for the production of low-energy ion beams of exotic, neutron-deficient Agisotopes. A proof-of-principle experiment has been realized by implanting primary 107Ag21+ ions from a heavy-ion cyclotron into a graphite catcher. A variable-thickness nickel foil was used to degrade the energy of the primary beam in order to mimic the implantation depth expected from the heavy-ion fusion-evaporation recoils of N = Z94Ag. Following implantation, the silver atoms diffused out of the graphite and effused into the catcher cavity and transfer tube, where they were resonantly laser ionized using a three-step excitation and ionization scheme. Following mass separation, the ions were identified by scanning the frequency of the first resonant excitation step while recording the ion count rate. Ion release time profiles were measured for different implantation depths and cavity temperatures with the mean delay time varying from 10 to 600 ms. In addition, the diffusio...

  1. An inductively heated hot cavity catcher laser ion source

    Energy Technology Data Exchange (ETDEWEB)

    Reponen, M., E-mail: mikael.reponen@riken.jp [Nuclear Physics Group, School of Physics and Astronomy, Schuster Laboratory, The University of Manchester, Brunswick Street, Manchester M13 9PL (United Kingdom); Moore, I. D., E-mail: iain.d.moore@jyu.fi; Pohjalainen, I.; Savonen, M.; Voss, A. [Department of Physics, University of Jyväskylä, Survontie 9, FI-40014 Jyväskylä (Finland); Rothe, S. [CERN, CH-1211, Geneva 23 (Switzerland); Sonnenschein, V. [Department of Quantum Engineering, Nagoya University, Nagoya, Aichi 464-8603 (Japan)

    2015-12-15

    An inductively heated hot cavity catcher has been constructed for the production of low-energy ion beams of exotic, neutron-deficient Ag isotopes. A proof-of-principle experiment has been realized by implanting primary {sup 107}Ag{sup 21+} ions from a heavy-ion cyclotron into a graphite catcher. A variable-thickness nickel foil was used to degrade the energy of the primary beam in order to mimic the implantation depth expected from the heavy-ion fusion-evaporation recoils of N = Z {sup 94}Ag. Following implantation, the silver atoms diffused out of the graphite and effused into the catcher cavity and transfer tube, where they were resonantly laser ionized using a three-step excitation and ionization scheme. Following mass separation, the ions were identified by scanning the frequency of the first resonant excitation step while recording the ion count rate. Ion release time profiles were measured for different implantation depths and cavity temperatures with the mean delay time varying from 10 to 600 ms. In addition, the diffusion coefficients for silver in graphite were measured for temperatures of 1470 K, 1630 K, and 1720 K, from which an activation energy of 3.2 ± 0.3 eV could be determined.

  2. The influence of aging and diabetes on heat transfer characteristics of the skin to a rapidly applied heat source.

    Science.gov (United States)

    Petrofsky, Jerrold; Lee, Haneul; Trivedi, Moxi; Hudlikar, Akshay N; Yang, Chia-hao; Goraksh, Neha; Alshammari, Faris; Mohanan, Mitali; Soni, Janhavi; Agilan, Brindha; Pai, Nikhila; Chindam, Tirupathi; Murugesan, Vengatesh; Yim, Jong Eun; Katrak, Vahishta

    2010-12-01

    Numerous studies have examined the blood flow of the skin at rest and in response to sustained heat and shown that, in older people and people with diabetes, the skin blood flow response to heat is diminished compared to younger people. It is not sustained heat, however, that usually causes burns; it is a more rapid application of heat. Ten younger subjects, 10 older subjects, and 10 subjects with diabetes were examined before and after applying a water-filled thermode to the skin above the quadriceps muscle to observe the changes in skin temperature and skin blood flow and the ability of the skin to absorb heat after a 2-min heat exposure with water at 44°C. Skin temperature rose from 31.2°C at rest to 38.3°C after 2 min of heat application in all subjects (P > 0.05 between groups). The calories required in the younger group of subjects was 2.26 times the calories required in the older group of subjects for the same change in skin temperature and 13.8 times the calories needed to increase skin temperature in the subjects with diabetes. Furthermore, the blood flow at rest was lower in people with diabetes than older subjects and both groups less than that seen in younger subjects. The blood flow response to heat was slower in the subjects with diabetes compared to the older subjects and much slower than that seen in the younger subjects. Reduced skin blood flow of older and subjects with diabetes, decreased thickness of the dermal layer, and increased subcutaneous fat, as well as damage to transient receptor potential vanilloid 1 receptors, may account for some of the differences between the groups.

  3. Analysis of heat generation and thermal lensing in erbium 3-µm lasers

    NARCIS (Netherlands)

    Pollnau, Markus

    2003-01-01

    The influence of energy-transfer upconversion (ETU) between neighboring ions in the upper and lower laser levels of erbium 3-um continuous-wave lasers on heat generation and thermal lensing is investigated. It is shown that the multiphonon relaxations following each ETU process generate significant

  4. Point, surface and volumetric heat sources in the thermal modelling of selective laser melting

    NARCIS (Netherlands)

    Yang, Y.; Ayas, C.; Brabazon, Dermot; Naher, Sumsun; Ul Ahad, Inam

    2017-01-01

    Selective laser melting (SLM) is a powder based additive manufacturing technique suitable for producing high precision metal parts. However, distortions and residual stresses within products arise during SLM because of the high temperature gradients created by the laser heating. Residual stresses

  5. Non-Fourier heat conduction and phase transition in laser ablation of polytetrafluoroethylene (PTFE)

    Science.gov (United States)

    Zhang, Yu; Zhang, Daixian; Wu, Jianjun; Li, Jian; He, Zhaofu

    2017-11-01

    The phase transition in heat conduction of polytetrafluoroethylene-like polymers was investigated and applied in many fields of science and engineering. Considering more details including internal absorption of laser radiation, reflectivity of material and non-Fourier effect etc., the combined heat conduction and phase transition in laser ablation of polytetrafluoroethylene were modeled and investigated numerically. The thermal and mechanic issues in laser ablation were illustrated and analyzed. Especially, the phenomenon of temperature discontinuity formed in the combined phase transition and non-Fourier heat conduction was discussed. Comparisons of target temperature profiles between Fourier and non-Fourier heat conduction in melting process were implemented. It was indicated that the effect of non-Fourier plays an important role in the temperature evolvement. The effect of laser fluence was proven to be significant and the thermal wave propagation was independent on the laser intensity for the non-Fourier heat conduction. Besides, the effect of absorption coefficients on temperature evolvements was studied. For different ranges of absorption coefficients, different temperature evolvements can be achieved. The above numerical simulation provided insight into physical processes of combined non-Fourier heat conduction and phase transition in laser ablation.

  6. Rapid prototyping of a micro pump with laser micromachining

    Science.gov (United States)

    Wong, C. Channy; Chu, Dahwey; Liu, Sally L.; Tuck, Melanie R.; Mahmud, Zahid; Amatucci, Vincent A.

    1995-09-01

    A microelectrohydrodynamic (EHD) injection pump has been developed using laser micromachining technoogy. Two desings have been fabricated, tested, and evaluated. The first design has two silicon pieces with KOH-etched wells which are stacked on the tpo of each other. The wells are etched on one side of the wafer and gold is deposited on the other side to serve as the pump electrodes. A Nd:YAG laser is used to drill an array of circular holes in the well region of both silicon parts. This creates a grid distribution with a square pattern. Next the well regions of the silicon parts are aligned, and the parts are bonded together using a Staystik thermoplastic. The pump unit is then mounted into a ceramic package with a large hole drilled in the bottom of the package to permit fluid flow. Aluminum ribbon wire bonds are used to connect the pump electrodes to the package leads. Isolation of metallization and wires is achieved by filling the package well and coating the wires with polyimide. When a voltage is applied at the electrodes, ions are injected into the working fluid, such as an organic solvent, thus inducing flow. The second design has the silicon parts oriented 'back-to-back' and bonded together with Stayform. A 'back-to-back' design will decrease the grid distance so that a smaller voltage is required for pumping. Preliminary results have demonstrated that this micropump can achieve a pressure head of about 287 Pa with an applied voltage of 120 Volt.

  7. Heat generation during ablation of porcine skin with erbium:YAG laser vs a novel picosecond infrared laser.

    Science.gov (United States)

    Jowett, Nathan; Wöllmer, Wolfgang; Mlynarek, Alex M; Wiseman, Paul; Segal, Bernard; Franjic, Kresimir; Krötz, Peter; Böttcher, Arne; Knecht, Rainald; Miller, R J Dwayne

    2013-08-01

    Despite significant advances in surgery, most surgical tools remain basic. Lasers provide a means of precise surgical ablation, but their clinical use has remained limited because of undesired thermal, ionizing, or acoustic stress effects leading to tissue injury. A novel ultrafast, nonionizing, picosecond infrared laser (PIRL) system has recently been developed and is capable, in theory, of ablation with negligible thermal or acoustic stress effects. To measure and compare heat generation by means of thermography during ablation of ex vivo porcine skin by conventional microsecond-pulsed erbium:YAG (Er:YAG) laser and picosecond infrared laser (PIRL). This study was conducted in an optics laboratory and used a pretest-posttest experimental design comparing 2 methods of laser ablation of tissue with each sample acting as its own control. Ex vivo porcine skin was ablated in a 5-mm line pattern with both Er:YAG laser and PIRL at fluence levels marginally above ablation threshold (2 J/cm² and 0.6 J/cm², respectively). Peaks and maxima of skin temperature rises were determined using a thermography camera. Means of peak temperature rises were compared using the paired sample t test. Ablation craters were assessed by means of digital microscopy. RESULTS Mean peak rise in skin surface temperature for the Er:YAG laser and PIRL was 15.0°C and 1.68°C, respectively (P skin surface temperature was 18.85°C for the Er:YAG laser and 2.05°C for the PIRL. Ablation craters were confirmed on digital microscopy. Picosecond infrared laser ablation results in negligible heat generation, considerably less than Er:YAG laser ablation, which confirms the potential of this novel technology in minimizing undesirable thermal injury associated with lasers currently in clinical use.

  8. ARTICLES: Heating of heat-conducting targets by laser pulses with a high-intensity leading spike

    Science.gov (United States)

    Ageev, Vladimir P.; Burdin, S. G.; Konov, Vitalii I.; Uglov, S. A.; Chapliev, N. I.

    1983-04-01

    The results of an analysis of the solution of a one-dimensional heat conduction equation are used to study the specific features of the thermal effects of laser pulses with a leading spike on a target. Simple criteria are obtained for establishing the ability of a pulse to cause a given increase in the target surface temperature during the leading edge of a spike and also during the tail of the laser pulse. A study is made of the influence of the inhomogeneity of the distribution of surface heat sources on the realization of processes characterized by a threshold in respect of the temperature of the irradiated surface. The results obtained are compared with the experimental delay time in the process of initiation of an air breakdown plasma by interaction of CO2 laser pulses with a metal target.

  9. X-ray reflectivity measurement of interdiffusion in metallic multilayers during rapid heating

    Science.gov (United States)

    Liu, J. P.; Kirchhoff, J.; Zhou, L.; Zhao, M.; Grapes, M. D.; Dale, D. S.; Tate, M. D.; Philipp, H. T.; Gruner, S. M.; Weihs, T. P.; Hufnagel, T. C.

    2017-01-01

    A technique for measuring interdiffusion in multilayer materials during rapid heating using X-ray reflectivity is described. In this technique the sample is bent to achieve a range of incident angles simultaneously, and the scattered intensity is recorded on a fast high-dynamic-range mixed-mode pixel array detector. Heating of the multilayer is achieved by electrical resistive heating of the silicon substrate, monitored by an infrared pyrometer. As an example, reflectivity data from Al/Ni heated at rates up to 200 K s−1 are presented. At short times the interdiffusion coefficient can be determined from the rate of decay of the reflectivity peaks, and it is shown that the activation energy for interdiffusion is consistent with a grain boundary diffusion mechanism. At longer times the simple analysis no longer applies because the evolution of the reflectivity pattern is complicated by other processes, such as nucleation and growth of intermetallic phases. PMID:28664887

  10. X-ray reflectivity measurement of interdiffusion in metallic multilayers during rapid heating.

    Science.gov (United States)

    Liu, J P; Kirchhoff, J; Zhou, L; Zhao, M; Grapes, M D; Dale, D S; Tate, M D; Philipp, H T; Gruner, S M; Weihs, T P; Hufnagel, T C

    2017-07-01

    A technique for measuring interdiffusion in multilayer materials during rapid heating using X-ray reflectivity is described. In this technique the sample is bent to achieve a range of incident angles simultaneously, and the scattered intensity is recorded on a fast high-dynamic-range mixed-mode pixel array detector. Heating of the multilayer is achieved by electrical resistive heating of the silicon substrate, monitored by an infrared pyrometer. As an example, reflectivity data from Al/Ni heated at rates up to 200 K s-1 are presented. At short times the interdiffusion coefficient can be determined from the rate of decay of the reflectivity peaks, and it is shown that the activation energy for interdiffusion is consistent with a grain boundary diffusion mechanism. At longer times the simple analysis no longer applies because the evolution of the reflectivity pattern is complicated by other processes, such as nucleation and growth of intermetallic phases.

  11. Feasibility of computed tomography based thermometry during interstitial laser heating in bovine liver

    Energy Technology Data Exchange (ETDEWEB)

    Pandeya, G.D. [University of Groningen, Department of Radiology, UMC Groningen, Hanzeplein 1, PO Box 30001, Groningen (Netherlands); Siemens AG, H IM CT PLM-E PA, Forchheim (Germany); Klaessens, J.H.G.M. [UMC Utrecht, Department of Medical Technology and Clinical Physics, Utrecht (Netherlands); Greuter, M.J.W.; Oudkerk, M. [University of Groningen, Department of Radiology, UMC Groningen, Hanzeplein 1, PO Box 30001, Groningen (Netherlands); Schmidt, B.; Flohr, T. [Siemens AG, H IM CT PLM-E PA, Forchheim (Germany); Hillegersberg, R. van [UMC Utrecht, Department of Surgical Oncology, Utrecht (Netherlands)

    2011-08-15

    To assess the feasibility of computed tomography (CT) based thermometry during interstitial laser heating in the bovine liver. Four freshly exercised cylindrical blocks of bovine tissue were heated using a continuous laser of Nd:YAG (wavelength: 1064 nm, active length: 30 mm, power: 10-30 W). All tissues were imaged at least once before and 7 times during laser heating using CT and temperatures were simultaneously measured with 5 calibrated thermal sensors. The dependency of the average CT numbers as a function of temperature was analysed with regression analysis and a CT thermal sensitivity was derived. During laser heating, the growing hypodense area was observed around the laser source and that area showed an increase as a function of time. The formation of hypodense area was caused by declining in CT numbers at increasing temperatures. The regression analysis showed an inverse linear dependency between temperature and average CT number with -0.65 {+-} 0.048 HU/ C (R{sup 2} = 0.75) for the range of 18-85 C in bovine liver. The non-invasive CT based thermometry during interstitial laser heating is feasible in the bovine liver. CT based thermometry could be further developed and may be of potential use during clinical LITT of the liver. (orig.)

  12. Low-level laser effects on bacterial cultures submitted to heat stress

    Science.gov (United States)

    Gonçalves, E. M.; Guimarães, O. R.; Geller, M.; Paoli, F.; Fonseca, A. S.

    2016-06-01

    Low-level lasers have been used worldwide to treat a number of diseases, pain relief, and wound healing. Some studies demonstrated that low-level laser radiations induce effects depending on the physiological state and DNA repair mechanisms of cells. In this work we evaluated the effects of low-level red and infrared lasers on Escherichia coli cells deficient in SOS responses submitted to heat stress. Exponential and stationary E. coli cultures of wild type (AB1157), RecA deficient (AB2463) and LexA deficient (AB2494), both SOS response deficient, were exposed to low-level red and infrared lasers at different fluences and submitted to heat stress (42 °C, 20 min). After that, cell survival and morphology were evaluated. Previous exposure to red, but not infrared lasers, increases survival fractions and decreases the area ratios of E. coli AB1157 cells submitted to heat stress. Our research suggests that a low-level red laser increases cell viability and protects cells from morphological alteration in E. coli cultures submitted to heat stress depending on laser wavelength and SOS response.

  13. In situ laser heating and radial synchrotron X-ray diffraction ina diamond anvil cell

    Energy Technology Data Exchange (ETDEWEB)

    Kunz, Martin; Caldwell, Wendel A.; Miyagi, Lowell; Wenk,Hans-Rudolf

    2007-06-29

    We report a first combination of diamond anvil cell radialx-ray diffraction with in situ laser heating. The laser-heating setup ofALS beamline 12.2.2 was modified to allow one-sided heating of a samplein a diamond anvil cell with an 80 W yttrium lithium fluoride laser whileprobing the sample with radial x-ray diffraction. The diamond anvil cellis placed with its compressional axis vertical, and perpendicular to thebeam. The laser beam is focused onto the sample from the top while thesample is probed with hard x-rays through an x-ray transparentboron-epoxy gasket. The temperature response of preferred orientation of(Fe,Mg)O is probed as a test experiment. Recrystallization was observedabove 1500 K, accompanied by a decrease in stress.

  14. Investigation of Heat Transfer in Mini Channels using Planar Laser Induced Fluorescence

    DEFF Research Database (Denmark)

    Bøgild, Morten Ryge; Poulsen, Jonas Lundsted; Rath, Emil Zacho

    2012-01-01

    In this paper an experimental investigation of the heat transfer in mini channels with a hydraulic diameter of 889 m is conducted. The method used is planar laser induceduorescence (PLIF), which uses the principle of laser excitation of rhodamine B in water. The goal of this study is to validate...... the applicability of PLIF to determine the convective heat transfer coecient in mini channels against conventional correlations of the convective heat transfer coecient. The applicability of the conventional theory in micro and mini channels has been discussed by several researchers, but to the authors knowledge...

  15. Effect of a low-level laser on bone regeneration after rapid maxillary expansion.

    Science.gov (United States)

    Cepera, Fernanda; Torres, Fernando C; Scanavini, Marco A; Paranhos, Luiz R; Capelozza Filho, Leopoldino; Cardoso, Mauricio A; Siqueira, Danieli C R; Siqueira, Danilo F

    2012-04-01

    In this study, we evaluated the effects of a low-level laser on bone regeneration in rapid maxillary expansion procedures. Twenty-seven children, aged 8 to 12 years, took part in the experiment, with a mean age of 10.2 years, divided into 2 groups: the laser group (n = 14), in which rapid maxillary expansion was performed in conjunction with laser use, and the no-laser group (n = 13), with rapid maxillary expansion only. The activation protocol of the expansion screw was 1 full turn on the first day and a half turn daily until achieving overcorrection. The laser type used was a laser diode (TWIN Laser; MMOptics, São Carlos, Brazil), according to the following protocol: 780 nm wavelength, 40 mW power, and 10 J/cm(2) density at 10 points located around the midpalatal suture. The application stages were 1 (days 1-5 of activation), 2 (at screw locking, on 3 consecutive days), 3, 4, and 5 (7, 14, and 21 days after stage 2). Occlusal radiographs of the maxilla were taken with the aid of an aluminum scale ruler as a densitometry reference at different times: T1 (initial), T2 (day of locking), T3 (3-5 days after T2), T4 (30 days after T3), and T5 (60 days after T4). The radiographs were digitized and submitted to imaging software (Image Tool; UTHSCSA, San Antonio, Tex) to measure the optic density of the previously selected areas. To perform the statistical test, analysis of covariance was used, with the time for the evaluated stage as the covariable. In all tests, a significance level of 5% (P maxillary expansion, provided efficient opening of the midpalatal suture and influenced the bone regeneration process of the suture, accelerating healing. Copyright © 2012 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

  16. Surface-selective laser sintering of thermolabile polymer particles using water as heating sensitizer

    Energy Technology Data Exchange (ETDEWEB)

    Antonov, E N; Krotova, L I; Minaev, N V; Minaeva, S A; Mironov, A V; Popov, V K [Institute on Laser and Information Technologies of the Russian Academy of Sciencies, Troitsk, Moscow (Russian Federation); Bagratashvili, V N [Department of Chemistry, M.V. Lomonosov Moscow State University, Moscow (Russian Federation)

    2015-11-30

    We report the implementation of a novel scheme for surface-selective laser sintering (SSLS) of polymer particles, based on using water as a sensitizer of laser heating and sintering of particles as well as laser radiation at a wavelength of 1.94 μm, corresponding to the strong absorption band of water. A method of sintering powders of poly(lactide-co-glycolide), a hydrophobic bioresorbable polymer, after modifying its surface with an aqueous solution of hyaluronic acid is developed. The sintering thresholds for wetted polymer are by 3 – 4 times lower than those for sintering in air. The presence of water restricts the temperature of the heated polymer, preventing its thermal destruction. Polymer matrices with a developed porous structure are obtained. The proposed SSLS method can be applied to produce bioresorbable polymer matrices for tissue engineering. (interaction of laser radiation with matter. laser plasma)

  17. Thermal and mechanical effect during rapid heating of astroloy for improving structural integrity

    Energy Technology Data Exchange (ETDEWEB)

    Popoolaa, A.P.I., E-mail: popoolaapi@tut.ac.za [Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria (South Africa); Oluwasegun, K.M. [Department of Materials Science and Engineering, Obafemi Awolowo University (Nigeria); Olorunniwo, O.E., E-mail: segun_nniwo@yahoo.com [Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria (South Africa); Department of Materials Science and Engineering, Obafemi Awolowo University (Nigeria); Atanda, P.O. [Department of Materials Science and Engineering, Obafemi Awolowo University (Nigeria); Aigbodion, V.S. [Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria (South Africa); Department of Metallurgical and Materials Engineering, University of Nigeria, Nsukka (Nigeria)

    2016-05-05

    The behaviour of γ′ phase to thermal and mechanical effects during rapid heating of Astroloy(Turbine Disc alloy) a Powder metallurgy (PM) nickel base superalloy has been investigated. The thermo-mechanical affected zone (TMAZ) and heat affected zone (HAZ) microstructure of an inertia friction welded Astroloy were simulated using a Gleeble thermo-mechanical simulation system. Detailed microstructural examination of the simulated TMAZ and HAZ and those present in actual inertial friction welded specimens showed that γ′ particles persisted during rapid heating up to a temperature where the formation of liquid is thermodynamically favoured, and subsequently re-solidified eutectically. The result obtained showed that forging during the thermo-mechanical simulation significantly enhanced resistance to weld liquation cracking of the alloy. This is attributable to strain-induced rapid isothermal dissolution of the constitutional liquation products within 150 μm from the centre of the forged sample. This was not observed in purely thermally simulated samples. The microstructure within the TMAZ of the as-welded alloy is similar to the microstructure in the forged Gleeble specimens. - Highlights: • The behaviour of γ′ phase to thermal and mechanical effects during rapid heating of Astrology • The thermo-mechanical affected zone (TMAZ) and heat affected zone (HAZ). • significantly enhanced resistance to weld liquation cracking of the alloy. • This was not observed in purely thermally simulated samples. • The microstructure within the TMAZ of the as-welded alloy is similar to the microstructure in the forged Gleeble specimens.

  18. Laser heating dynamics and glow spectra of carbon-, titanium- and erbium-containing optothermal fibre converters for laser medicine

    Science.gov (United States)

    Belikov, A. V.; Skrypnik, A. V.

    2017-07-01

    Titanium- and erbium-containing optothermal fibre converters of laser radiation mounted at the distal end of quartz-quartz optical fibre are discussed for the first time. Technology of fabricating such converters is described. Carbon-containing converters are also considered. The laser heating dynamics of the converters and the glow spectra are studied by irradiating converters of each type by a 980 ± 10 nm semiconductor laser with an average power up to 4 W. It is shown that alongside with broadband thermal radiation accompanying the laser heating of all three types of converters in the temperature range 600-1100 °C, only in the spectrum of the erbium-containing converter the intense bands with the maxima at wavelengths 493, 523, 544, 660, and 798 nm, corresponding to the erbium radiative transitions 4F7/2 → 4I15/2, 2H11/2 → 4I15/2, 4S3/2 → 4I15/2, 4F9/2 → 4I15/2 and 4I9/2 → 4I15/2, respectively, are present. Such converters can be used in laser medicine for tissue surgery as well as in procedures combining laser, thermal, biostimulation or photodynamic action.

  19. On the effect of laterally varying boundary heat flux on rapidly rotating spherical shell convection

    Science.gov (United States)

    Sahoo, Swarandeep; Sreenivasan, Binod

    2017-08-01

    The onset of convection in a rotating spherical shell subject to laterally varying heat flux at the outer boundary is considered in this paper. The focus is on the geophysically relevant regime of rapid rotation (low Ekman number) where the natural length scale of convection is significantly smaller than the length scale imposed by the boundary heat flux pattern. Contrary to earlier studies at a higher Ekman number, we find a substantial reduction in the onset Rayleigh number Rac with increasing lateral variation. The decrease in Rac is shown to be closely correlated to the equatorial heat flux surplus in the steady, basic state solution. The consistency of such a correlation makes the estimation of Rac possible without solving the full stability problem. The steady baroclinic flow has a strong cyclone-anticyclone asymmetry in the kinetic helicity only for equatorially symmetric lateral variations, with possible implications for dynamo action. Equatorially antisymmetric variations, on the other hand, break the symmetry of the mean flow, in turn negating its helicity. Analysis of the perturbation solution reveals strongly localized clusters through which convection rolls drift in and out at a frequency higher than that for the reference case with homogeneous boundary heat flux. Large lateral variations produce a marked decrease in the azimuthal length scale of columns, which indicates that small-scale motions are essential to the transport of heat in rapidly rotating, localized convection. With an equatorially antisymmetric heat flux pattern, convection in individual clusters goes through an asynchronous wax-wane cycle whose frequency is much lower than the drift rate of the columns. These continual variations in convection intensity may in turn result in fluctuations in the magnetic field intensity, an effect that needs to be considered in dynamo models. Finally, there is a notable analogy between the role of a laterally varying boundary heat flux and the role of a

  20. Measurement of weldpiece distortion during pulsed laser welding using rapid laser profilometry

    OpenAIRE

    Gorkič, Aleš; Jezeršek, Matija; Možina, Janez; Diaci, Janez

    2015-01-01

    The present paper reports a new setup for acquisition of shape data for weldpieces during pulsed laser welding. The setup is based on illumination of the weldpiece surface by laser light, which is structured as multiple light planes, and acquisition of the image of the illuminated surface by a digital camera. The position of the optical system is fixed relative to the measured weldpiece. The acquired image is fed into a personal computer where it is processed to obtain the three-dimensional s...

  1. Rapid, non-destructive and non-contact inspection of solid foods by means of photothermal radiometry; thermal effusivity and initial heating coefficient

    Science.gov (United States)

    Gijsbertsen, A.; Bicanic, D.; Gielen, J. L. W.; Chirtoc, M.

    2004-03-01

    CO 2-laser photothermal radiometry (PTR) was demonstrated to be suitable for the non-destructive and non-contact characterization (both optical and thermal) of solid phase agricultural commodities (fresh vegetables, fruits) and confectionery products (candy). Proper interpretation of PTR signals enable one to calculate two parameters, i.e. the well known thermal effusivity e ( e= λρc p, where λ and ρcp are the thermal conductivity and the volume specific heat, respectively) and a newly introduced physical quantity termed 'initial heating coefficient' chi ( χ= β/( ρcp), β is the absorption coefficient). Obtained values for e are in a good agreement with data reported in the literature. PTR enables one to rapidly determine e via a single measurement. As opposed to this, the knowledge of two out of three thermophysical parameters (thermal diffusivity, thermal conductivity and volume specific heat) is a condition sine qua non for determining effusivity in the conventional manner.

  2. Rapid prototyping of biodegradable microneedle arrays by integrating CO2 laser processing and polymer molding

    Science.gov (United States)

    Tu, K. T.; Chung, C. K.

    2016-06-01

    An integrated technology of CO2 laser processing and polymer molding has been demonstrated for the rapid prototyping of biodegradable poly-lactic-co-glycolic acid (PLGA) microneedle arrays. Rapid and low-cost CO2 laser processing was used for the fabrication of a high-aspect-ratio microneedle master mold instead of conventional time-consuming and expensive photolithography and etching processes. It is crucial to use flexible polydimethylsiloxane (PDMS) to detach PLGA. However, the direct CO2 laser-ablated PDMS could generate poor surfaces with bulges, scorches, re-solidification and shrinkage. Here, we have combined the polymethyl methacrylate (PMMA) ablation and two-step PDMS casting process to form a PDMS female microneedle mold to eliminate the problem of direct ablation. A self-assembled monolayer polyethylene glycol was coated to prevent stiction between the two PDMS layers during the peeling-off step in the PDMS-to-PDMS replication. Then the PLGA microneedle array was successfully released by bending the second-cast PDMS mold with flexibility and hydrophobic property. The depth of the polymer microneedles can range from hundreds of micrometers to millimeters. It is linked to the PMMA pattern profile and can be adjusted by CO2 laser power and scanning speed. The proposed integration process is maskless, simple and low-cost for rapid prototyping with a reusable mold.

  3. Laser induced breakdown spectroscopy (LIBS) as a rapid tool for material analysis

    Science.gov (United States)

    Hussain, T.; Gondal, M. A.

    2013-06-01

    Laser induced breakdown spectroscopy (LIBS) is a novel technique for elemental analysis based on laser-generated plasma. In this technique, laser pulses are applied for ablation of the sample, resulting in the vaporization and ionization of sample in hot plasma which is finally analyzed by the spectrometer. The elements are identified by their unique spectral signatures. LIBS system was developed for elemental analysis of solid and liquid samples. The developed system was applied for qualitative as well as quantitative measurement of elemental concentration present in iron slag and open pit ore samples. The plasma was generated by focusing a pulsed Nd:YAG laser at 1064 nm on test samples to study the capabilities of LIBS as a rapid tool for material analysis. The concentrations of various elements of environmental significance such as cadmium, calcium, magnesium, chromium, manganese, titanium, barium, phosphorus, copper, iron, zinc etc., in these samples were determined. Optimal experimental conditions were evaluated for improving the sensitivity of developed LIBS system through parametric dependence study. The laser-induced breakdown spectroscopy (LIBS) results were compared with the results obtained using standard analytical technique such as inductively couple plasma emission spectroscopy (ICP). Limit of detection (LOD) of our LIBS system were also estimated for the above mentioned elements. This study demonstrates that LIBS could be highly appropriate for rapid online analysis of iron slag and open pit waste.

  4. Laser induced rapid decontamination of aromatic compound from porous soil simulant

    Science.gov (United States)

    Zheng, Wenjun; Hou, Sichao; Su, Ming

    2017-08-01

    Soil contamination with organic compounds can lead to the loss of farmable and habitable lands and cause long-term human and animal exposure to toxins. This paper reports a new laser based method for in situ soil decontamination at high efficiency, in which a focused excimer laser is used to remove organic contaminants from soil through burning by generating a local high temperature region. An aromatic compound, 1,1-dichloro-2,2-bis(4-chlorophenyl) ethylene, is used as an organic contaminant, and a porous silica plate is used as a soil simulant. A heat transfer model is created to simulate the interaction between the laser and the organic compound. The lithographic mode of operation allows the accurate quantitation of laser effects. The effects of power, speed, frequency, and energy consumption on the efficiency of decontamination have been examined with high accuracy. The decomposition area increases with the increase in the laser power and the decrease in the scan speed and frequency. Given the high energy conversion yield of the high power laser, this method would be promising for large scale in situ soil decontamination.

  5. Laser heating: a minimally invasive technique for studying fire-generated heating in building stone

    Directory of Open Access Journals (Sweden)

    Ocaña, José Luis

    2008-06-01

    Full Text Available Due to the irreparable damage it can cause, fire is one of the major risks to buildings. Recent studies on the effects of fire tend to focus on micro-scale analysis, addressing questions such as micro-cracking or mineralogical or chemical changes that are particularly relevant to listed buildings.The fire simulation techniques employed to date (convection heating laboratory furnaces and real flame tests are subject to a series of limitations including non-repeatability, the lack of combustion by-products and, most importantly, the need to work with large samples. In this final context, techniques must be found that require only minimal sample sizes.This paper introduces laser irradiation as a technique suitable for simulating the “combustion” of building materials, since it mimics the physics of fire, is repeatable, yields combustion products and, most importantly, can be applied to small specimens. Indeed, as laser irradiation concentrates high amounts of energy in small areas, it can be used for micro-scale testing.El fuego es una de las amenazas más importantes para los edificios debido a la escala de pérdidas irreparables que genera. Los estudios sobre los efectos del fuego se han dirigido recientemente hacia escalas de observación más detalladas, que son más adecuadas para el estudio de muestras de edificios patrimoniales, como microfisuración y cambios mineralógicos y químicos.Las técnicas de simulación de fuegos empleadas hasta ahora (ensayos con hornos y llamas reales presentan varias limitaciones como, por ejemplo, la falta de repetibilidad, ausencia de sub-productos de combustión o, especialmente, el uso de muestras de gran tamaño. Por esta última razón, es importante encontrar técnicas en las que se pueda usar cantidades mínimas de muestra.Este artículo presenta la irradiación láser como una técnica adecuada para simular el “quemado” de materiales de construcción, ya que ofrece una física de

  6. Scattering effect in radiative heat transfer during selective laser sintering of polymers

    Science.gov (United States)

    Liu, Xin; Boutaous, M'hamed; Xin, Shihe

    2016-10-01

    The aim of this work is to develop an accurate model to simulate the selective laser sintering (SLS) process, in order to understand the multiple phenomena occurring in the material and to study the influence of each parameter on the quality of the sintered parts. A numerical model, coupling radiative and conductive heat transfers in a polymer powder bed providing a local temperature field, is proposed. To simulate the polymer sintering by laser heating as in additive manufacturing, a double-lines scanning of a laser beam over a thin layer of polymer powder is studied. An effective volumetric heat source, using a modified Monte Carlo method, is estimated from laser radiation scattering and absorption in a semi-transparent polymer powder bed. In order to quantify the laser-polymer interaction, the heating and cooling of the material is modeled and simulated with different types heat sources by both finite elements method (FEM) and discrete elements method (DEM). To highlight the importance of introducing a semi-transparent behavior of such materials and in order to validate our model, the results are compared with works taken from the literature.

  7. Industrial femtosecond lasers for machining of heat-sensitive polymers (Conference Presentation)

    Science.gov (United States)

    Hendricks, Frank; Bernard, Benjamin; Matylitsky, Victor V.

    2017-03-01

    Heat-sensitive materials, such as polymers, are used increasingly in various industrial sectors such as medical device manufacturing and organic electronics. Medical applications include implantable devices like stents, catheters and wires, which need to be structured and cut with minimum heat damage. Also the flat panel display market moves from LCD displays to organic LED (OLED) solutions, which utilize heat-sensitive polymer substrates. In both areas, the substrates often consist of multilayer stacks with different types of materials, such as metals, dielectric layers and polymers with different physical characteristic. The different thermal behavior and laser absorption properties of the materials used makes these stacks difficult to machine using conventional laser sources. Femtosecond lasers are an enabling technology for micromachining of these materials since it is possible to machine ultrafine structures with minimum thermal impact and very precise control over material removed. An industrial femtosecond Spirit HE laser system from Spectra-Physics with pulse duration 120 μJ and average output powers of >16 W is an ideal tool for industrial micromachining of a wide range of materials with highest quality and efficiency. The laser offers process flexibility with programmable pulse energy, repetition rate, and pulse width. In this paper, we provide an overview of machining heat-sensitive materials using Spirit HE laser. In particular, we show how the laser parameters (e.g. laser wavelength, pulse duration, applied energy and repetition rate) and the processing strategy (gas assisted single pass cut vs. multi-scan process) influence the efficiency and quality of laser processing.

  8. Investigation on the optimized heat treatment procedure for laser fabricated IN718 alloy

    Science.gov (United States)

    Zhang, Yaocheng; Yang, Li; Chen, Tingyi; Zhang, Weihui; Huang, Xiwang; Dai, Jun

    2017-12-01

    The laser fabricated IN718 alloys were prepared by laser cladding system. The microstructure and microhardness of laser fabricated IN718 alloys were investigated after heat treatment. The microstructure and the elevated temperature mechanical properties of laser fabricated IN718 alloys were analyzed. The results showed that the microstructure of laser fabricated IN718 alloy consisted of austenitic matrix and dendritic Laves/γ eutectic. Most all Laves/γ eutectic was dissolved into austenitic matrix, and the complete recrystallization and the large grains occurred in the laser fabricated IN718 alloy after homogenization at 1080-1140 °C for 1 h, the dendritic Laves/γ eutectic was refined and the partial recrystallization occurred during the solid solution at 940-1000 °C for 1.5 h, the microhardness of the double aging (DA) alloys was about more than twice that of as-fabricated IN718 alloy. The recrystallized microstructure was obtained in the heat-treated laser fabricated IN718 alloy after 1100 °C/1 h air cooling (AC), 980 °C/1.5 h (AC), 700 °C/8 h furnace cooling (FC, 100 °C/h) to 600 °C/8 h (AC). The microhardness and the elevated temperature tensile strength were more than twice that of as-fabricated IN718 alloy due to a large concentration of γ″ phase precipitation to improve the transgranular strength and large grain to guarantee the grain boundary strength. The fracture morphologies of as-fabricated and heat-treated laser fabricated IN718 alloys were presented as the fiber dimples, the fracture mechanism of as-fabricated and heat-treated laser fabricated IN718 alloys was ductile fracture.

  9. Laser heat hyperalgesia is not a feature of non-specific chronic low back pain.

    Science.gov (United States)

    Franz, M; Ritter, A; Puta, C; Nötzel, D; Miltner, W H R; Weiss, T

    2014-11-01

    Based upon studies using mechanical pin-prick, pressure, electrical or heat stimuli applied to painful and/or pain-free parts of the body, chronic low back pain (CLBP) has been shown to be associated with generalized and enhanced pain sensitivity and altered brain responses to noxious stimuli. To date, no study examined the processing of noxious laser heat pulses, which are known to selectively excite thermal nociceptors located in the superficial skin layers, in CLBP. We studied laser heat pain thresholds (LHPTs) and nociceptive laser-evoked brain electrical potentials (LEPs) following skin stimulation of the pain-affected back and the pain-free abdomen using noxious laser heat stimulation in 16 CLBP patients and 16 age- and gender-matched healthy controls (HCs). We observed no statistically significant differences in LHPTs between CLBP patients and HCs, neither on the back nor on the abdomen. Furthermore, we found no evidence for altered brain responses between CLBP patients and HCs in response to stimulation of the back and abdomen in single-trial latencies and amplitudes of LEP components (N2, P2). The results are in contrast to previous studies showing hypersensitivity to different experimental noxious stimuli (e.g., contact heat). We argue that these discrepancies may be due to low spatial and temporal summation within the central nervous system following laser heat stimulation. Our results indicate important methodological differences between laser heat and thermode stimulation that should be taken into account when interpreting results, such as from thermal quantitative sensory testing. © 2014 European Pain Federation - EFIC®

  10. Rapid selective metal patterning on polydimethylsiloxane (PDMS) fabricated by capillarity-assisted laser direct write

    KAUST Repository

    Lee, Ming-Tsang

    2011-08-12

    In this study we demonstrate a novel approach for the rapid fabricating micro scale metal (silver) patterning directly on a polydimethylsiloxane (PDMS) substrate. Silver nanoparticles were sintered on PDMS to form conductive metal films using laser direct write (LDW) technology. To achieve good metal film quality, a capillarity-assisted laser direct writing (CALDW) of nanoparticle suspensions on a low surface energy material (PDMS) was utilized. Experimental results showed controllable electrical conductivities and good film properties of the sintered silver patterns. This study reveals an advanced method of metal patterning on PDMS, and proposes a new research application of LDW in a nanoparticle colloidal environment. © 2011 IOP Publishing Ltd.

  11. Laser and LED phototherapy on midpalatal suture after rapid maxilla expansion: Raman and histological analysis.

    Science.gov (United States)

    Rosa, Cristiane Becher; Habib, Fernando Antonio Lima; de Araújo, Telma Martins; Dos Santos, Jean Nunes; Cangussu, Maria Cristina T; Barbosa, Artur Felipe Santos; de Castro, Isabele Cardoso Vieira; Pinheiro, Antônio Luiz Barbosa

    2017-02-01

    The aim of this study was to analyze the effect of laser or LED phototherapy on the acceleration of bone formation at the midpalatal suture after rapid maxilla expansion. Forty-five rats were divided into groups at 7 days (control, expansion, expansion and laser irradiation, and expansion and LED irradiation) and into 14 days (expansion, expansion and laser in the 1st week, expansion and LED in the 1st week, expansion and laser in the 1st and 2nd weeks, expansion and LED in the 1st and 2nd weeks). Laser/LED irradiation occurred every 48 h. Expansion was accomplished with a spatula and maintained with a triple helicoid of 0.020-in stainless steel orthodontic wire. A diode laser (λ780 nm, 70 mW, spot of 0.04 cm2, t = 257 s, SAEF of 18 J/cm2) or a LED (λ850 ± 10 nm, 150 ± 10 mW, spot of 0.5 cm2, t = 120 s, SAEF of 18 J/cm2) was applied in one point in the midpalatal suture immediately behind the upper incisors. Raman spectroscopy and histological analyses of the suture region were carried and data was submitted to statistical analyses (p ≤ 0.05). Raman spectrum analysis demonstrated that irradiation increases hydroxyapatite in the midpalatal suture after expansion. In the histological analysis of various inflammation, there was a higher production of collagen and osteoblastic activity and less osteoclastic activity. The results showed that LED irradiation associated to rapid maxillary expansion improves bone repair and could be an alternative to the use of laser in accelerating bone formation in the midpalatal suture.

  12. Thermal transport in shock wave-compressed solids using pulsed laser heating.

    Science.gov (United States)

    La Lone, B M; Capelle, G; Stevens, G D; Turley, W D; Veeser, L R

    2014-07-01

    A pulsed laser heating method was developed for determining thermal transport properties of solids under shock-wave compression. While the solid is compressed, a laser deposits a known amount of heat onto the sample surface, which is held in the shocked state by a transparent window. The heat from the laser briefly elevates the surface temperature and then diffuses into the interior via one-dimensional heat conduction. The thermal effusivity is determined from the time history of the resulting surface temperature pulse, which is recorded with optical pyrometry. Thermal effusivity is the square root of the product of thermal conductivity and volumetric heat capacity and is the key thermal transport parameter for relating the surface temperature to the interior temperature of the sample in a dynamic compression experiment. Therefore, this method provides information that is needed to determine the thermodynamic state of the interior of a compressed metal sample from a temperature measurement at the surface. The laser heat method was successfully demonstrated on tin that was shock compressed with explosives to a stress and temperature of ~25 GPa and ~1300 K. In this state, tin was observed to have a thermal effusivity of close to twice its ambient value. The implications on determining the interior shock wave temperature of tin are discussed.

  13. Benefits of CO2 laser heating for high reliability fiber splicing

    Science.gov (United States)

    Duke, Douglas M.; Nasir, Usman; Saravanos, Elli

    2016-03-01

    The use of a CO2 laser as a heat source became commercially available for optical fiber splicing and component fabrication only in recent years. In addition to long-term trouble-free and low-maintenance heat source operation, laser fusion splicing offers unique benefits for fabricating high-power optical components, as well as for splice reliability. When used as the heating method for fiber splicing, the energy of the CO2 laser beam is efficiently absorbed by the outer layer of the glass, and is then conducted inwards. This heating method is well controlled, and results in a smooth and contamination-free glass surface. Other heating methods, such as arc fusion or resistive heating, may leave tungsten, graphite, or metal oxide deposits on the spliced fiber surface. By contrast, with CO2 laser splicing, the lack of surface irregularities and contamination enables remarkable spliced-fiber strength results, with some strength results nearly within the range of coated fiber breaking strength.

  14. Mass And Heat Transfer In Deep Penetration Laser Welding

    Science.gov (United States)

    Cantello, Maichi; Cruciani, Diego; Ciboldi, Moreno; Onorato, Michele

    1987-09-01

    The phenomena related to deep penetration welding by means of concentrated energy beams are, in a first approximation, similar, even if the beam sources (electron and laser beams) and the irradiated materials (metals, quartz) differ. Clearly however, if the temperature distribution and the material flow dynamics are to be calculated, it can be seen that these similarities are merely qualitative, and consist of the presence of a vapour tube (key-hole) in the processed material. The mathematical models hitherto developed correspond exactly to experiments at a certain distance from the interaction point. Although several authors have investigated the physical condition of the key-hole, both theoretically and experimentally, additional data are needed in order to obtain satisfactory data of the temperatures and flows of the vapour and liquid metal, at least as far as the most common laser welding application is concerned. In the RTM laser centre, the data obtained by the various investigation methods are being correlated systematically. The devices most widely used are a fast framing camera, a fast slide to intercept the laser beam and a vacuum chamber for welding in a controlled atmosphere. The two CO2 laser sources used can vary their power from 1 kW to 15 kW. Data regarding stainless steel are dealt with in the greatest detail since this is the principal application of laser welding.

  15. Development of Experimental Setup of Metal Rapid Prototyping Machine using Selective Laser Sintering Technique

    Science.gov (United States)

    Patil, S. N.; Mulay, A. V.; Ahuja, B. B.

    2016-08-01

    Unlike in the traditional manufacturing processes, additive manufacturing as rapid prototyping, allows designers to produce parts that were previously considered too complex to make economically. The shift is taking place from plastic prototype to fully functional metallic parts by direct deposition of metallic powders as produced parts can be directly used for desired purpose. This work is directed towards the development of experimental setup of metal rapid prototyping machine using selective laser sintering and studies the various parameters, which plays important role in the metal rapid prototyping using SLS technique. The machine structure in mainly divided into three main categories namely, (1) Z-movement of bed and table, (2) X-Y movement arrangement for LASER movements and (3) feeder mechanism. Z-movement of bed is controlled by using lead screw, bevel gear pair and stepper motor, which will maintain the accuracy of layer thickness. X-Y movements are controlled using timing belt and stepper motors for precise movements of LASER source. Feeder mechanism is then developed to control uniformity of layer thickness metal powder. Simultaneously, the study is carried out for selection of material. Various types of metal powders can be used for metal RP as Single metal powder, mixture of two metals powder, and combination of metal and polymer powder. Conclusion leads to use of mixture of two metals powder to minimize the problems such as, balling effect and porosity. Developed System can be validated by conducting various experiments on manufactured part to check mechanical and metallurgical properties. After studying the results of these experiments, various process parameters as LASER properties (as power, speed etc.), and material properties (as grain size and structure etc.) will be optimized. This work is mainly focused on the design and development of cost effective experimental setup of metal rapid prototyping using SLS technique which will gives the feel of

  16. Electrowetting-based microfluidic operations on rapid-manufactured devices for heat pipe applications

    Science.gov (United States)

    Hale, Renee S.; Bahadur, Vaibhav

    2017-07-01

    The heat transport capacity of traditional heat pipes is limited by the capillary pressure generated in the internal wick that pumps condensate to the evaporator. Recently, the authors conceptualized a novel heat pipe architecture, wherein wick-based pumping is replaced by electrowetting (EW)-based pumping of microliter droplets in the adiabatic section. An electrowetting heat pipe (EHP) can overcome the capillary limit to heat transport capacity and enable compact, planar, gravity-insensitive, and ultralow power consumption heat pipes that transport kiloWatt heat loads over extended distances. This work develops a novel technique for rapid, scalable fabrication of EW-based devices and studies critical microfluidic operations underlying the EHP, with the objective of predicting the key performance parameters of the EHP. Devices are fabricated on a printed circuit board (PCB) substrate with mechanically-milled electrodes, and a removable polyimide dielectric film. The first set of experiments uncovers the maximum channel gap (1 mm) for reliable EW-based pumping; this parameter determines the heat transport capacity of the EHP, which scales linearly with the channel gap. The second set of experiments uncovers the maximum channel gap (375 microns) at which EW voltages can successfully split droplets. This is an important consideration which ensures EHP operability in the event of unintentional droplet merging. The third set of experiments demonstrate and study EW-induced droplet generation from an open-to-air reservoir, which mimics the interface between the condenser and adiabatic sections of the EHP. The experimental findings predict that planar, water-based EHPs with a (10 cm by 4 mm) cross section can transport 1.6 kW over extended distances (>1 m), with a thermal resistance of 0.01 K W-1.

  17. Determination of the heat transfer capability of laser mirrors with cooled cells

    Science.gov (United States)

    Zhernovyi, Yu. V.; Odnorozhenko, I. G.; Potyagailo, D. B.; Romanchuk, Ya. P.

    1992-09-01

    A mathematical model of steady-state heat transfer in a laser mirror involving cooled prismatically shaped cells has been developed. Using cooling systems with hexahedral and tetrahedral cells (by the number of side walls) as examples, the influence of the mirror illumination nonuniformity, reflector thickness, and other parameters on the effective heat-transfer coefficient and thermal head coefficient is investigated; the physical limits for heat-transfer characteristics in the case of an unlimited increase in heat transfer from the surfaces of the cell walls have been determined.

  18. A method for rapid measurement of laser ablation rate of hard dental tissue

    Science.gov (United States)

    Perhavec, T.; Gorkič, A.; Bračun, D.; Diaci, J.

    2009-06-01

    The aim of the study reported here is the development of a new method which allows rapid and accurate in-vitro measurements of three-dimensional (3D) shape of laser ablated craters in hard dental tissues and the determination of crater volume, ablation rate and speed. The method is based on the optical triangulation principle. A laser sheet projector illuminates the surface of a tooth, mounted on a linear translation stage. As the tooth is moved by the translation stage a fast digital video camera captures series of images of the illuminated surface. The images are analyzed to determine a 3D model of the surface. Custom software is employed to analyze the 3D model and to determine the volume of the ablated craters. Key characteristics of the method are discussed as well as some practical aspects pertinent to its use. The method has been employed in an in-vitro study to examine the ablation rates and speeds of the two main laser types currently employed in dentistry, Er:YAG and Er,Cr:YSGG. Ten samples of extracted human molar teeth were irradiated with laser pulse energies from 80 mJ to the maximum available energy (970 mJ with the Er:YAG, and 260 mJ with the Er,Cr:YSGG). About 2000 images of each ablated tooth surface have been acquired along a translation range of 10 mm, taking about 10 s and providing close to 1 million surface measurement points. Volumes of 170 ablated craters (half of them in dentine and the other half in enamel) were determined from this data and used to examine the ablated volume per pulse energy and ablation speed. The results show that, under the same conditions, the ablated volume per pulse energy achieved by the Er:YAG laser exceeds that of the Er,Cr:YSGG laser in almost all regimes for dentine and enamel. The maximum Er:YAG laser ablation speeds (1.2 mm 3/s in dentine and 0.7 mm 3/s in enamel) exceed those obtained by the Er,Cr:YSGG laser (0.39 mm 3/s in dentine and 0.12 mm 3/s in enamel). Since the presented method proves to be easy to

  19. Linear terrestrial laser scanning using array avalanche photodiodes as detectors for rapid three-dimensional imaging.

    Science.gov (United States)

    Cai, Yinqiao; Tong, Xiaohua; Tong, Peng; Bu, Hongyi; Shu, Rong

    2010-12-01

    As an active remote sensor technology, the terrestrial laser scanner is widely used for direct generation of a three-dimensional (3D) image of an object in the fields of geodesy, surveying, and photogrammetry. In this article, a new laser scanner using array avalanche photodiodes, as designed by the Shanghai Institute of Technical Physics of the Chinese Academy of Sciences, is introduced for rapid collection of 3D data. The system structure of the new laser scanner is first presented, and a mathematical model is further derived to transform the original data to the 3D coordinates of the object in a user-defined coordinate system. The performance of the new laser scanner is tested through a comprehensive experiment. The result shows that the new laser scanner can scan a scene with a field view of 30° × 30° in 0.2 s and that, with respect to the point clouds obtained on the wall and ground floor surfaces, the root mean square errors for fitting the two planes are 0.21 and 0.01 cm, respectively. The primary advantages of the developed laser scanner include: (i) with a line scanning mode, the new scanner achieves simultaneously the 3D coordinates of 24 points per single laser pulse, which enables it to scan faster than traditional scanners with a point scanning mode and (ii) the new scanner makes use of two galvanometric mirrors to deflect the laser beam in both the horizontal and the vertical directions. This capability makes the instrument smaller and lighter, which is more acceptable for users.

  20. Heat shock protein expression as guidance for the therapeutic window of retinal laser therapy

    Science.gov (United States)

    Wang, Jenny; Huie, Philip; Dalal, Roopa; Lee, Seungjun; Tan, Gavin; Lee, Daeyoung; Lavinksy, Daniel; Palanker, Daniel

    2016-03-01

    Unlike conventional photocoagulation, non-damaging retinal laser therapy (NRT) limits laser-induced heating to stay below the retinal damage threshold and therefore requires careful dosimetry. Without the adverse effects associated with photocoagulation, NRT can be applied to critical areas of the retina and repeatedly to manage chronic disorders. Although the clinical benefits of NRT have been demonstrated, the mechanism of therapeutic effect and width of the therapeutic window below damage threshold are not well understood. Here, we measure activation of heat shock response via laser-induced hyperthermia as one indication of cellular response. A 577 nm laser is used with the Endpoint Management (EpM) user interface, a titration algorithm, to set experimental pulse energies relative to a barely visible titration lesion. Live/dead staining and histology show that the retinal damage threshold in rabbits is at 40% of titration energy on EpM scale. Heat shock protein 70 (HSP70) expression in the retinal pigment epithelium (RPE) was detected by whole-mount immunohistochemistry after different levels of laser treatment. We show HSP70 expression in the RPE beginning at 25% of titration energy indicating that there is a window for NRT between 25% and 40% with activation of the heat shock protein expression in response to hyperthermia. HSP70 expression is also seen at the perimeter of damaging lesions, as expected based on a computational model of laser heating. Expression area for each pulse energy setting varied between laser spots due to pigmentation changes, indicating the relatively narrow window of non-damaging activation and highlighting the importance of proper titration.

  1. Laser welding head tailored to tube-sheet joint requirements for heat exchangers manufacturing

    OpenAIRE

    Vandewynckéle, Ambroise; Vaamonde, Eva; Fontán, Marcos; Herwig, Patrick; Mascioletti, Alessandro

    2013-01-01

    Tube to tube-sheet joints in heat exchangers are currently welded by the orbital TIG process characterized by very high quality of the weld beads and good repeatability. However, due to high number of welds, a reduction in the welding cycle time would have an interesting impact on manufacturing costs and delays and laser welding technology is aimed to improve this factor. The main disadvantage is the positioning accuracy required by the laser welding process since beam deviations from real jo...

  2. Microstructure Evolution and Biodegradation Behavior of Laser Rapid Solidified Mg–Al–Zn Alloy

    Directory of Open Access Journals (Sweden)

    Chongxian He

    2017-03-01

    Full Text Available The too fast degradation of magnesium (Mg alloys is a major impediment hindering their orthopedic application, despite their superior mechanical properties and favorable biocompatibility. In this study, the degradation resistance of AZ61 (Al 6 wt. %, Zn 1 wt. %, remaining Mg was enhanced by rapid solidification via selective laser melting (SLM. The results indicated that an increase of the laser power was beneficial for enhancing degradation resistance and microhardness due to the increase of relative density and formation of uniformed equiaxed grains. However, too high a laser power led to the increase of mass loss and decrease of microhardness due to coarsened equiaxed grains and a reduced solid solution of Al in the Mg matrix. In addition, immersion tests showed that the apatite increased with the increase of immersion time, which indicated that SLMed AZ61 possessed good bioactivity.

  3. Effect of Laser Feeding on Heat Treated Aluminium Alloy Surface Properties

    Directory of Open Access Journals (Sweden)

    Labisz K.

    2016-06-01

    Full Text Available In this paper are presented the investigation results concerning microstructure as well as mechanical properties of the surface layer of cast aluminium-silicon-copper alloy after heat treatment alloyed and/ or remelted with SiC ceramic powder using High Power Diode Laser (HPDL. For investigation of the achieved structure following methods were used: light and scanning electron microscopy with EDS microanalysis as well as mechanical properties using Rockwell hardness tester were measured. By mind of scanning electron microscopy, using secondary electron detection was it possible to determine the distribution of ceramic SiC powder phase occurred in the alloy after laser treatment. After the laser surface treatment carried out on the previously heat treated aluminium alloys, in the structure are observed changes concerning the distribution and morphology of the alloy phases as well as the added ceramic powder, these features influence the hardness of the obtained layers. In the structure, there were discovered three zones: the remelting zone (RZ the heat influence zone (HAZ and transition zone, with different structure and properties. In this paper also the laser treatment conditions: the laser power and ceramic powder feed rate were investigated. The surface laser structure changes in a manner, that there zones are revealed in the form of. This carried out investigations make it possible to develop, interesting technology, which could be very attractive for different branches of industry.

  4. Heat accumulation in ultra-short pulsed scanning laser ablation of metals.

    Science.gov (United States)

    Bauer, Franziska; Michalowski, Andreas; Kiedrowski, Thomas; Nolte, Stefan

    2015-01-26

    High average laser powers can have a serious adverse impact on the ablation quality in ultra-short pulsed laser material processing of metals. With respect to the scanning speed, a sharp transition between a smooth, reflective and an uneven, dark ablated surface is observed. Investigating the influence of the sample temperature, it is experimentally shown that this effect stems from heat accumulation. In a numerical heat flow simulation, the critical scanning speed indicating the change in ablation quality is determined in good agreement with the experimental data.

  5. Development of a new laser heating system for thin film growth by chemical vapor deposition

    Science.gov (United States)

    Fujimoto, Eiji; Sumiya, Masatomo; Ohnishi, Tsuyoshi; Lippmaa, Mikk; Takeguchi, Masaki; Koinuma, Hideomi; Matsumoto, Yuji

    2012-09-01

    We have developed a new laser heating system for thin film growth by chemical vapor deposition (CVD). A collimated beam from a high-power continuous-wave 808 nm semiconductor laser was directly introduced into a CVD growth chamber without an optical fiber. The light path of the heating laser inside the chamber was isolated mechanically from the growth area by bellows to protect the optics from film coating. Three types of heat absorbers, (10 × 10 × 2 mm3) consisting of SiC, Ni/NiOx, or pyrolytic graphite covered with pyrolytic BN (PG/PBN), located at the backside of the substrate, were tested for heating performance. It was confirmed that the substrate temperature could reach higher than 1500 °C in vacuum when a PG/PBN absorber was used. A wide-range temperature response between 400 °C and 1000 °C was achieved at high heating and cooling rates. Although the thermal energy loss increased in a H2 gas ambient due to the higher thermal conductivity, temperatures up to 1000°C were achieved even in 200 Torr H2. We have demonstrated the capabilities of this laser heating system by growing ZnO films by metalorganic chemical vapor deposition. The growth mode of ZnO films was changed from columnar to lateral growth by repeated temperature modulation in this laser heating system, and consequently atomically smooth epitaxial ZnO films were successfully grown on an a-plane sapphire substrate.

  6. Nonlocal heat transport and improved target design for x-ray heating studies at x-ray free electron lasers

    Science.gov (United States)

    Hoidn, Oliver; Seidler, Gerald T.

    2018-01-01

    The extremely high-power densities and short durations of single pulses of x-ray free electron lasers (XFELs) have opened new opportunities in atomic physics, where complex excitation-relaxation chains allow for high ionization states in atomic and molecular systems, and in dense plasma physics, where XFEL heating of solid-density targets can create unique dense states of matter having temperatures on the order of the Fermi energy. We focus here on the latter phenomena, with special emphasis on the problem of optimum target design to achieve high x-ray heating into the warm dense matter (WDM) state. We report fully three-dimensional simulations of the incident x-ray pulse and the resulting multielectron relaxation cascade to model the spatial energy density deposition in multicomponent targets, with particular focus on the effects of nonlocal heat transport due to the motion of high energy photoelectrons and Auger electrons. We find that nanoscale high-Z /low-Z multicomponent targets can give much improved energy density deposition in lower-Z materials, with enhancements reaching a factor of 100. This has three important benefits. First, it greatly enlarges the thermodynamic parameter space in XFEL x-ray heating studies of lower-Z materials. Second, it allows the use of higher probe photon energies, enabling higher-information content x-ray diffraction (XRD) measurements such as in two-color XFEL operations. Third, while this is merely one step toward optimization of x-ray heating target design, the demonstration of the importance of nonlocal heat transport establishes important common ground between XFEL-based x-ray heating studies and more traditional laser plasma methods.

  7. Wavelength shifting of intra-cavity photons: Adiabatic wavelength tuning in rapidly wavelength-swept lasers.

    Science.gov (United States)

    Jirauschek, Christian; Huber, Robert

    2015-07-01

    We analyze the physics behind the newest generation of rapidly wavelength tunable sources for optical coherence tomography (OCT), retaining a single longitudinal cavity mode during operation without repeated build up of lasing. In this context, we theoretically investigate the currently existing concepts of rapidly wavelength-swept lasers based on tuning of the cavity length or refractive index, leading to an altered optical path length inside the resonator. Specifically, we consider vertical-cavity surface-emitting lasers (VCSELs) with microelectromechanical system (MEMS) mirrors as well as Fourier domain mode-locked (FDML) and Vernier-tuned distributed Bragg reflector (VT-DBR) lasers. Based on heuristic arguments and exact analytical solutions of Maxwell's equations for a fundamental laser resonator model, we show that adiabatic wavelength tuning is achieved, i.e., hopping between cavity modes associated with a repeated build up of lasing is avoided, and the photon number is conserved. As a consequence, no fundamental limit exists for the wavelength tuning speed, in principle enabling wide-range wavelength sweeps at arbitrary tuning speeds with narrow instantaneous linewidth.

  8. A New Method for the Determination of the Specific Heat Capacity Using Laser-Flash Calorimetry Down to 77K

    Science.gov (United States)

    Göbel, A.; Hemberger, F.; Vidi, S.; Ebert, H.-P.

    2013-05-01

    A new method for evaluation of the specific heat capacity in the temperature regime between 77K and 330K using laser-flash calorimetry is presented. Usually, laser-flash calorimetry is accomplished by performing an additional laser-flash measurement on a reference specimen with a known specific heat capacity and by comparing the maximum rear-side temperatures rises. In this study, the calibration is achieved by comparison of the rear-side temperature rise to specific-heat-capacity data determined by other methods in an adjacent temperature regime. Subsequently, the thus yielded proportional factor is used for the evaluation of the specific heat capacity from laser-flash measurements at temperatures where no specific-heat-capacity data are available. The reliability of this method is shown by performing measurements on a material with known specific heat capacity, aluminum oxide. Furthermore, the specific heat capacity and thermal conductivity of borosilicate crown glass (BK7) was determined experimentally.

  9. Heat generation above break-even from laser-induced fusion in ultra-dense deuterium

    OpenAIRE

    Leif Holmlid

    2015-01-01

    Previous results from laser-induced processes in ultra-dense deuterium D(0) give conclusive evidence for ejection of neutral massive particles with energy >10 MeV u−1. Such particles can only be formed from nuclear processes like nuclear fusion at the low laser intensity used. Heat generation is of interest for future fusion energy applications and has now been measured by a small copper (Cu) cylinder surrounding the laser target. The temperature rise of the Cu cylinder is measured with an NT...

  10. Transformation of silver nanowires into nanoparticles by Rayleigh instability: Comparison between laser irradiation and heat treatment

    Science.gov (United States)

    Oh, Harim; Lee, Jeeyoung; Lee, Myeongkyu

    2018-01-01

    We comparatively study the morphological evolutions of silver nanowires under nanosecond-pulsed laser irradiation and thermal treatment in ambient air. While single-crystalline, pure Ag nanospheres could be produced by laser-driven Rayleigh instability, the particles produced by heat treatment were subject to oxidation and exhibited polyhedron shapes. The different results are attributed to the significantly different time scales of the two processes. In this article, we also show that bimetallic Ag-Au nanospheres can be synthesized by irradiating Ag nanowires coated with a thin Au film using a pulsed laser beam. This may provide a facile route to tune the plasmonic behavior of metal nanoparticles.

  11. Influence of non-collisional laser heating on the electron dynamics in dielectric materials

    CERN Document Server

    Barilleau, L; Chimier, B; Geoffroy, G; Tikhonchuk, V

    2016-01-01

    The electron dynamics in dielectric materials induced by intense femtosecond laser pulses is theoretically addressed. The laser driven temporal evolution of the energy distribution of electrons in the conduction band is described by a kinetic Boltzmann equation. In addition to the collisional processes for energy transfer such as electron-phonon-photon and electron-electron interactions, a non-collisional process for photon absorption in the conduction band is included. It relies on direct transitions between sub-bands of the conduction band through multiphoton absorption. This mechanism is shown to significantly contribute to the laser heating of conduction electrons for large enough laser intensities. It also increases the time required for the electron distribution to reach the equilibrium state as described by the Fermi-Dirac statistics. Quantitative results are provided for quartz irradiated by a femtosecond laser pulse with a wavelength of 800 nm and for intensities in the range of tens of TW/cm$^2$, lo...

  12. Structural changes in nanostructured catalytic oxides monitored by Raman spectroscopy: Effect of the laser heating

    Science.gov (United States)

    Oliveira, Alcemira C.; da Silva, Antonio N.; Junior, Jose Alves L.; Freire, Paulo T. C.; Oliveira, Alcineia C.; Filho, Josué M.

    2017-03-01

    The laser power effects on the structural properties of nanostructured oxides were studied by Raman spectroscopy. The nanostructured CeO2, ZrO2, SnO2, TiO2 and MnOx oxides were prepared by a nanocasting route and characterized through various physicochemical techniques. The structural features of the solids were accompanied by varying the incident laser power from 2.0 to 9.1 mW. The laser caused local heating on the surface of the nanostructured solids and influenced on their particle sizes. The CeO2, TiO2 and MnOx spectra exhibited particle size changes due to thermal effects. Elevated laser power up to 9.1 mW accelerated the sintering of CeO2, TiO2 and MnOx particles in contrast to SnO2 counterparts. Simultaneously, the creation of defects in the aforesaid oxide structures was suggested upon increasing the laser power from 2.0 to 9.1 mW. The phase transformation from MnOx-related phases to α-Mn2O3 and the oxidation of these phases were observed. Tetragonal ZrO2 showed a very stable structure under laser heating, envisaging further catalytic applications upon using mild laser power.

  13. Point, surface and volumetric heat sources in the thermal modelling of selective laser melting

    Science.gov (United States)

    Yang, Yabin; Ayas, Can

    2017-10-01

    Selective laser melting (SLM) is a powder based additive manufacturing technique suitable for producing high precision metal parts. However, distortions and residual stresses within products arise during SLM because of the high temperature gradients created by the laser heating. Residual stresses limit the load resistance of the product and may even lead to fracture during the built process. It is therefore of paramount importance to predict the level of part distortion and residual stress as a function of SLM process parameters which requires a reliable thermal modelling of the SLM process. Consequently, a key question arises which is how to describe the laser source appropriately. Reasonable simplification of the laser representation is crucial for the computational efficiency of the thermal model of the SLM process. In this paper, first a semi-analytical thermal modelling approach is described. Subsequently, the laser heating is modelled using point, surface and volumetric sources, in order to compare the influence of different laser source geometries on the thermal history prediction of the thermal model. The present work provides guidelines on appropriate representation of the laser source in the thermal modelling of the SLM process.

  14. Rapid prototyping of reflectors for vehicle lighting using laser activated remote phosphor

    Science.gov (United States)

    Lachmayer, Roland; Kloppenburg, Gerolf; Wolf, Alexander

    2015-03-01

    Bright white light sources are of significant importance for automotive front lighting systems. Today's upper class vehicles mainly use HID or LED as light source. As a further step in this development laser diode based systems offer high luminance, efficiency and allow the realization of new styling concepts and new dynamic lighting functions. These white laser diode systems can either be realized by mixing different spectral sources or by combining diodes with specific phosphors. Based on the approach of generating light using a laser and remote phosphor, lighting modules are manufactured. Four blue laser diodes (450 nm) are used to activate a phosphor coating and thus to achieve white light. A segmented paraboloid reflector generates the desired light distribution for an additional car headlamp. We use high speed milling and selective laser melting to build the reflector system for this lighting module. We compare the spectral reflection grade of these materials. Furthermore the generated modules are analyzed regarding their efficiency and light distribution. The use of Rapid Prototyping technologies allows an early validation of the chosen concept and is supposed to reduce cost and time in the product development process significantly. Therefor we discuss costs and times of the applied manufacturing technologies.

  15. Laser Induced Fluorescence (LIF) Nondestructive Evaluation of Incipient Heat Damage in Polymer Matrix Composites, A2476

    Science.gov (United States)

    2017-02-15

    02-2017 2. REPORT TYPE Final 3. DATES COVERED (From - To) Oct 2011 - Jul 2016 4. TITLE AND SUBTITLE Laser Induced Fluorescence (LIF...Instances of mechanical strength degradation from incipient heat damage in aircraft PMCs exceeding 60% have been reported (Fisher et al., 1995). Currently...forms of exposure. Bowie’s master’s thesis (2017) includes a review of the scientific and engineering literature on incipient heat damage in PMCs

  16. Rapid systemic up-regulation of genes after heat-wounding and electrical stimulation

    Science.gov (United States)

    Davies, E.; Vian, A.; Vian, C.; Stankovic, B.

    1997-01-01

    When one leaf of a tomato plant is electrically-stimulated or heat-wounded, proteinase inhibitor genes are rapidly up-regulated in distant leaves. The identity of the systemic wound signal(s) is not yet known, but major candidates include hormones transmitted via the phloem or the xylem, the electrically-stimulated self-propagating electrical signal in the phloem (the action potential, AP), or the heat-wound-induced surge in hydraulic pressure in the xylem evoking a local change in membrane potential in adjacent living cells (the variation potential, VP). In order to discriminate between these signals we have adopted two approaches. The first approach involves applying stimuli that evoke known signals and determining whether these signals have similar effects on the "model" transcripts for proteinase inhibitors (pin) and calmodulin (cal). Here we show that a heat wound almost invariably evokes a VP, while an electrical stimulation occasionally evokes an AP, and both of these signals induce accumulation of transcripts encoding proteinase inhibitors. The second approach involves identifying the array of genes turned on by heat-wounding. To this end, we have constructed a subtractive library for heat-wounded tissue, isolated over 800 putatively up-regulated clones, and shown that all but two of the fifty that we have analyzed by Northern hybridization are, indeed, up-regulated. Here we show the early kinetics of up-regulation of three of these transcripts in the terminal (4th) leaf in response to heat-wounding the 3rd leaf, about 5 cm away. Even though these transcripts show somewhat different time courses of induction, with one peaking at 30 min, another at 15 min, and another at 5 min after flaming of a distant leaf, they all exhibit a similar pattern, i.e., a transient period of transcript accumulation preceding a period of transcript decrease, followed by a second period of transcript accumulation.

  17. Hybrid Particle-In-Cell (PIC) simulation of heat transfer and ionization balance in overdense plasmas irradiated by subpicosecond pulse lasers

    Energy Technology Data Exchange (ETDEWEB)

    Zhidkov, A.; Sasaki, Akira [Japan Atomic Energy Research Inst., Neyagawa, Osaka (Japan). Kansai Research Establishment

    1998-11-01

    A 1D hybrid electromagnetic particle-in-cell code with new methods to include particle collisions and atomic kinetics is developed and applied to ultra-short-pulse laser plasma interaction. Using the Langevin equation to calculate the Coulomb collision term, the present code is shown to be fast and stable in calculating the particle motion in the PIC simulation. Furthermore, by noting that the scale length of the change of atomic kinetics is much longer than the Debye radius, we calculate ionization and X-ray emission on kinetics cells, which are determined by averaging plasma parameters such as the electron density and energy over number of PIC cells. The absorption of short-pulse laser by overdense plasmas is calculated in self-consistent manner, including the effect of rapid change of density and temperature caused by instantaneous heating and successive fast ionization of the target material. The calculated results agree well with those obtained from the Fokker-Planck simulation as well as experiments, for non-local heat transport in plasmas with steep temperature gradient, and for the absorption of a short laser pulse by solid density targets. These results demonstrate usefulness of the code and the computational method therein for understanding of physics of short pulse laser plasma interaction experiments, and for application to the gain calculation of short-pulse laser excited X-ray laser as well. (author)

  18. Voltage generation of piezoelectric cantilevers by laser heating.

    Science.gov (United States)

    Hsieh, Chun-Yi; Liu, Wei-Hung; Chen, Yang-Fang; Shih, Wan Y; Gao, Xiaotong; Shih, Wei-Heng

    2012-11-15

    Converting ambient thermal energy into electricity is of great interest in harvesting energy from the environment. Piezoelectric cantilevers have previously been shown to be an effective biosensor and a tool for elasticity mapping. Here we show that a single piezoelectric (lead-zirconate titanate (PZT)) layer cantilever can be used to convert heat to electricity through pyroelectric effect. Furthermore, piezoelectric-metal (PZT-Ti) bi-layer cantilever showed an enhanced induced voltage over the single PZT layer alone due to the additional piezoelectric effect. This type of device can be a way for converting heat energy into electricity.

  19. Energetic peculiarities of metal heating under laser welding

    Energy Technology Data Exchange (ETDEWEB)

    Oparin, M.I.; Nikiforov, G.D.; Fedorov, S.A. (Moskovskij Aviatsionnyj Tekhnologicheskij Inst. (USSR))

    1981-07-01

    A connection between the energy and thermal parameters of the welding process of laser welding is studied. It is established that the connection between energy and thermal parameters of laser welding regime is carried out through the coefficient of metal absorption. Experimental determination of absorption coefficients of various metals (aluminium alloys, copper, 12Kh18N10T steel, St 3 steel, 0T4 titanium alloy, VN2 niobium alloy) has permitted to develope the methodics of approximated thermal calculations and to built up a nomogram for determining parameters of lazer welding regime. Limits of the thickness of welded sheets of the above materials in dependence on the welding speed are determined according to the nomogram.

  20. Analysis of laser-induced heating in optical neuronal guidance

    DEFF Research Database (Denmark)

    Ebbesen, Christian L.; Bruus, Henrik

    2012-01-01

    Recently, it has been shown that it is possible to control the growth direction of neuronal growth cones by stimulation with weak laser light; an effect dubbed optical neuronal guidance. The effect exists for a broad range of laser wavelengths, spot sizes, spot intensities, optical intensity...... of the guided neuron have been neglected in the optical neuronal guidance literature. The results of our finite-element-method simulations show the relevance of the temperature field in optical guidance experiments and are consistent with published experimental results and modeling in the field of optical traps....... Furthermore, we propose two experiments designed to test this hypotheses experimentally. For one of these experiments, we have designed a microfluidic platform, to be made using standard microfabrication techniques, for incubation of neurons in temperature gradients on micrometer lengthscales....

  1. Laser surface modification of medical grade alloys for reduced heating in a magnetic resonance imaging environment

    Science.gov (United States)

    Benafan, O.; Chen, S.-Y.; Kar, A.; Vaidyanathan, R.

    2015-12-01

    Nanoscale surface modification of medical grade metallic alloys was conducted using a neodymium-doped yttrium aluminum garnet laser-based dopant diffusion technique. The objective of this approach was to minimize the induction heating by reducing the absorbed radio frequency field. Such an approach is advantageous in that the dopant is diffused into the alloy and is not susceptible to detachment or spallation as would an externally applied coating, and is expected to not deteriorate the mechanical and electrical properties of the base alloy or device. Experiments were conducted using a controlled environment laser system with the ability to control laser properties (i.e., laser power, spot size, and irradiation time) and dopant characteristics (i.e., temperature, concentration, and pressure). The reflective and transmissive properties of both the doped and untreated samples were measured in a radio frequency (63.86 MHz) magnetic field using a system comprising a high power signal generator, a localized magnetic field source and sensor, and a signal analyzer. The results indicate an increase in the reflectivity of the laser-treated samples compared to untreated samples. The effect of reflectivity on the heating of the alloys is investigated through a mathematical model incorporating Maxwell's equations and heat conduction.

  2. The role of radiation transport in the thermal response of semitransparent materials to localized laser heating

    Energy Technology Data Exchange (ETDEWEB)

    Colvin, Jeffrey [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Shestakov, Aleksei [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Stolken, James [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Vignes, Ryan [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2011-03-09

    Lasers are widely used to modify the internal structure of semitransparent materials for a wide variety of applications, including waveguide fabrication and laser glass damage healing. The gray diffusion approximation used in past models to describe radiation cooling is not adequate for these materials, particularly near the heated surface layer. In this paper we describe a computational model based upon solving the radiation transport equation in 1D by the Pn method with ~500 photon energy bands, and by multi-group radiationdiffusion in 2D with fourteen photon energy bands. The model accounts for the temperature-dependent absorption of infrared laser light and subsequent redistribution of the deposited heat by both radiation and conductive transport. We present representative results for fused silica irradiated with 2–12 W of 4.6 or 10.6 µm laser light for 5–10 s pulse durations in a 1 mm spot, which is small compared to the diameter and thickness of the silica slab. Furthermore, we show that, unlike the case for bulk heating, in localized infrared laser heatingradiation transport plays only a very small role in the thermal response of silica.

  3. Compression and heating of a laser-produced plasma using single and double induction coils

    Science.gov (United States)

    Creel, J. R.; Lunney, J. G.

    2018-02-01

    The results of an experiment on magnetohydrodynamic compression and heating of a laser-produced plasma in vacuum are described. The plasma was produced by laser ablation of copper at 2 J cm-2. A pulsed magnetic field, with an amplitude of 0.3 T and a period of 2.2 µs, was produced by a three-turn spiral induction coil placed 10 mm above the ablation spot. Time-resolved imaging revealed that the magnetic field had a strong influence on both the plasma between the coil and the target, and on the plasma which flows through the aperture in the coil. The plasma flow through the coil aperture is strongly pinched due to the Lorentz interaction of the induced current and the coil magnetic field. Heating of the plasma is evidenced by strong enhancement of the overall visible light emission and the appearance of Cu+ line emission. Magnetic compression and plasma heating were also observed in a setup using two induction coils separated by 10 mm. This technique could be used to enhance the sensitivity of laser-induced breakdown spectroscopy, increase the ion yield in laser plasma ion sources, or control the ablation plume expansion in pulsed laser deposition.

  4. Influence of heat input on HAZ liquation cracking in laser welded GH909 alloy

    Science.gov (United States)

    Yan, Fei; Hu, Chongjing; Zhang, Xiong; Cai, Yuanzheng; Wang, Chunming; Wang, Jun; Hu, Xiyuan

    2017-07-01

    In this paper, we describe influence of heat input on HAZ liquation cracking in laser welded GH909 alloy. The results demonstrated that more cracks were produced using high laser power and welding speed. The presence of cracks greatly weakened the hot ductility of this material and the binding force between the adjacent grains, resulting in reducing the tensile strength of welded joints. The occurrence of HAZ cracking was mainly attributable to the coarseness of microstructures and large tensile stresses. A new method was proposed to prevent HAZ liquation cracking using low laser power and welding speed at a constant heat input. The simulated results were consistent with the experimental results, verifying the correctness and feasibility of the method.

  5. Surface-selective laser sintering of thermolabile polymer particles using water as heating sensitizer

    Science.gov (United States)

    Antonov, E. N.; Krotova, L. I.; Minaev, N. V.; Minaeva, S. A.; Mironov, A. V.; Popov, V. K.; Bagratashvili, V. N.

    2015-11-01

    We report the implementation of a novel scheme for surface-selective laser sintering (SSLS) of polymer particles, based on using water as a sensitizer of laser heating and sintering of particles as well as laser radiation at a wavelength of 1.94 μm, corresponding to the strong absorption band of water. A method of sintering powders of poly(lactide-co-glycolide), a hydrophobic bioresorbable polymer, after modifying its surface with an aqueous solution of hyaluronic acid is developed. The sintering thresholds for wetted polymer are by 3 - 4 times lower than those for sintering in air. The presence of water restricts the temperature of the heated polymer, preventing its thermal destruction. Polymer matrices with a developed porous structure are obtained. The proposed SSLS method can be applied to produce bioresorbable polymer matrices for tissue engineering.

  6. Modelling the Heating Process in Simultaneous Laser Transmission Welding of Semicrystalline Polymers

    Directory of Open Access Journals (Sweden)

    Christian Hopmann

    2016-01-01

    Full Text Available Laser transmission welding is an established joining process for thermoplastics. A close-to-reality simulation of the heating process would improve the understanding of the process, facilitate and shorten the process installation, and provide a significant contribution to the computer aided component design. For these reasons a thermal simulation model for simultaneous welding was developed which supports determining the size of the heat affected zone (HAZ. The determination of the intensity profile of the laser beam after the penetration of the laser transparent semicrystalline thermoplastic is decisive for the simulation. For the determination of the intensity profile two measurement systems are presented and compared. The calculated size of the HAZ shows a high concordance to the dimensions of the HAZ found using light microscopy. However, the calculated temperatures exceed the indicated decomposition temperatures of the particular thermoplastics. For the recording of the real temperatures during the welding process a measuring system is presented and discussed.

  7. Pulsed laser heating of silicon-nitride capped GaAs: Optical properties at high temperature

    Science.gov (United States)

    Bhat, A.; Yao, H. D.; Compaan, A.; Horak, A.; Rys, A.

    1988-09-01

    The optical properties of silicon nitride and gallium arsenide were studied at temperatures up to and beyond the melting point of GaAs by means of laser heating. XeCl excimer and pulsed dye laser pulses, ˜10 ns in duration, were used to heat the semiconductor under nitride capping layers of varying thickness. The transient reflectivity response at 514.5 nm was used together with a multilayer interference analysis to obtain the optical constants of solid and molten GaAs and of solid Si3N4 near the 1513-K melting point of GaAs. In addition, we report the melt duration as a function of laser pulse energy for GaAs with and without capping layers.

  8. EXCIMER-LASER ABLATION OF SOFT-TISSUE - A STUDY OF THE CONTENT OF RAPIDLY EXPANDING AND COLLAPSING BUBBLES

    NARCIS (Netherlands)

    van Leeuwen, T. G.; Jansen, E. D.; Motamedi, M.; Welch, A. J.; Borst, C.

    1994-01-01

    Both holmium (lambda = 2.09 mum) and excimer (lambda = 308 nm) lasers are used for ablation of tissue. In a previous study, excimer laser ablation of aorta produced rapidly expanding and collapsing vapor bubbles. To investigate whether the excimer-induced bubble is caused by vaporization of (tissue)

  9. Reduction in lateral thermal damage using heat-conducting templates: a comparison of continuous wave and pulsed CO2 lasers.

    Science.gov (United States)

    Spector, Nicole; Spector, Jared; Ellis, Darrel L; Reinisch, Lou

    2003-01-01

    The advantages of the continuous wave (c.w.) CO(2) laser are offset by the delay in laser wound healing secondary to thermal damage. We have developed novel heat-conducting templates to reduce laser thermal damage. Because shortened pulse durations also decrease thermal damage, we tested the effectiveness of heat-conducting templates with a c.w. CO(2) clinical laser and a short-pulsed CO(2) laser to determine the best method and mechanism to minimize thermal damage. Comparison of 0.2-second shuttered c.w. and 5-microsecond pulsed CO(2) lasers were made by doing incisions on 150 tissue samples from reduction mammoplasties and abdominoplasties. Copper, aluminum, glass, and Plexiglass heat-conducting templates were tested against no template (air) with both lasers. Histological samples were evaluated using computerized morphometrics analysis. Statistically significant reductions in lateral thermal damage were seen with the copper (50%) and aluminum (39%) templates used with the c.w. CO(2) laser. Only the copper template (39%) significantly reduced thermal damage when used with the pulsed CO(2) laser. Less thermal damage was seen using the pulsed CO(2) laser compared to the c.w. CO(2) laser with each template. Heat-conducting templates significantly reduced the amount of lateral thermal damage when used with the c.w. CO(2) laser (copper and aluminum) and short-pulsed CO(2) laser (copper). The c.w. CO(2) laser with the copper template compared favorably to the short-pulsed CO(2) laser without a template. Therefore, both heat conductive templates and short-pulse structure provide successful methods for reducing lateral thermal damage, and a combination of the two appears to provide optimal results.

  10. Impact of thermodynamic properties and heat loss on ignition of transportation fuels in rapid compression machines

    KAUST Repository

    Ahmed, Ahfaz

    2018-01-30

    Rapid compression machines (RCM) are extensively used to study autoignition of a wide variety of fuels at engine relevant conditions. Fuels ranging from pure species to full boiling range gasoline and diesel can be studied in an RCM to develop a better understanding of autoignition kinetics in low to intermediate temperature ranges. In an RCM, autoignition is achieved by compressing a fuel/oxidizer mixture to higher pressure and temperature, thereby initiating chemical reactions promoting ignition. During these experiments, the pressure is continuously monitored and is used to deduce significant events such as the end of compression and the onset of ignition. The pressure profile is also used to assess the temperature evolution of the gas mixture with time using the adiabatic core hypothesis and the heat capacity ratio of the gas mixture. In such RCM studies, real transportation fuels containing many components are often represented by simpler surrogate fuels. While simpler surrogates such as primary reference fuels (PRFs) and ternary primary reference fuel (TPRFs) can match research and motor octane number of transportation fuels, they may not accurately replicate thermodynamic properties (including heat capacity ratio). This non-conformity could exhibit significant discrepancies in the end of compression temperature, thereby affecting ignition delay (τign) measurements. Another aspect of RCMs that can affect τign measurement is post compression heat loss, which depends on various RCM parameters including geometry, extent of insulation, pre-heating temperature etc. To, better understand the effects of these non-chemical kinetic parameters on τign, thermodynamic properties of a number of FACE G gasoline surrogates were calculated and simulated in a multi-zone RCM model. The problem was further investigated using a variance based analysis and individual sensitivities were calculated. This study highlights the effects on τign due to thermodynamic properties of

  11. Application of laser measuring, numerical simulation and rapid prototyping to titanium dental castings.

    Science.gov (United States)

    Wu, M; Tinschert, J; Augthun, M; Wagner, I; Schädlich-Stubenrauch, J; Sahm, P R; Spiekermann, H

    2001-03-01

    This paper describes a method of making titanium dental crowns by means of integrating laser measuring, numerical simulation and rapid prototype (RP) manufacture of wax patterns for the investment casting process. Four real tooth crowns (FDI No. 24, 25, 26, 27) were measured by means of 3D laser scanning. The laser digitized geometry of the crowns was processed and converted into standard CAD models in STL format, which is used by RP systems and numerical simulation software. Commercial software (MAGMASOFT) was used to simulate the casting process and optimize the runner and gating system (sprue) design. RP crowns were 'printed' directly on a ModelMaker II 3D Plotting System. A silicone negative mold (soft tool) was made from the RP crowns, then more than hundreds wax crowns were duplicated. The duplicated crowns were joined to the optimized runner and gating system. By using the investment casting process 20-25 replicas of each crown were made on a centrifugal casting machine. All castings were examined for porosity by X-ray radiographs. By using the integrated scanning, simulation, RP pattern and casting procedure, cast crowns, free of porosity, with excellent functional contour and a smooth surface finish, were obtained from the first casting trial. The coupling of laser digitizing and RP indicates a potential to replace the traditional 'impression taking and waxing' procedure in dental laboratory, with the quality of the cast titanium prostheses also being improved by using the numerically optimized runner and gating system design.

  12. Hybrid Processing Combining Electrostatic Levitation and Laser Heating: Application to Terrestrial Analogues of Asteroid Materials

    Directory of Open Access Journals (Sweden)

    Paul-François Paradis

    2011-01-01

    Full Text Available Electrostatic levitation combined with laser heating is becoming a mature technique that has been used for several fundamental and applied studies in fluid and materials sciences (synthesis, property determination, solidification studies, atomic dynamic studies, etc.. This is attributable to the numerous processing conditions (containerless, wide heating temperature range, cooling rates, atmospheric compositions, etc. that levitation and radiative heating offer, as well as to the variety of diagnostics tools that can be used. In this paper, we describe the facility, highlighting the combined advantages of electrostatic levitation and laser processing. The various capabilities of the facility are discussed and are exemplified with the measurements of the density of selected iron-nickel alloys taken over the liquid phase.

  13. Surge in the heating market. Renewable energies rapidly gaining market share; Wende im Waermemarkt. Erneuerbare Energien gewinnen rasant an Marktanteilen

    Energy Technology Data Exchange (ETDEWEB)

    Briese, Dirk; Hein, Thomas; Gatena, Jens [trend:research GmbH Institut fuer Trend- und Marktforschung, Bremen (Germany)

    2009-10-15

    The proportion of heat produced from renewable energies is rapidly growing in Germany. The main reasons for this dynamic development are governmental funds for heating technologies based on renewable energy, the growing importance attached by large parts of the population to environmentally responsible energy production and the rising costs of fossil fuels. Biomass plants, solar thermal installations and heat pumps will be widely used in upcoming refurbishment and new building projects, as a recent study shows.

  14. Properties and Developments of Combustion and Gasification of Coal and Char in a CO2-Rich and Recycled Flue Gases Atmosphere by Rapid Heating

    Directory of Open Access Journals (Sweden)

    Zhigang Li

    2012-01-01

    Full Text Available Combustion and gasification properties of pulverized coal and char have been investigated experimentally under the conditions of high temperature gradient of order 200°C·s−1 by a CO2 gas laser beam and CO2-rich atmospheres with 5% and 10% O2. The laser heating makes a more ideal experimental condition compared with previous studies with a TG-DTA, because it is able to minimize effects of coal oxidation and combustion by rapid heating process like radiative heat transfer condition. The experimental results indicated that coal weight reduction ratio to gases followed the Arrhenius equation with increasing coal temperature; further which were increased around 5% with adding H2O in CO2-rich atmosphere. In addition, coal-water mixtures with different water/coal mass ratio were used in order to investigate roles of water vapor in the process of coal gasification and combustion. Furthermore, char-water mixtures with different water/char mass ratio were also measured in order to discuss the generation ratio of CO/CO2, and specified that the source of Hydrocarbons is volatile matter from coal. Moreover, it was confirmed that generations of CO and Hydrocarbons gases are mainly dependent on coal temperature and O2 concentration, and they are stimulated at temperature over 1000°C in the CO2-rich atmosphere.

  15. Microstructural Characterization Of Laser Heat Treated AISI 4140 Steel With Improved Fatigue Behavior

    Directory of Open Access Journals (Sweden)

    Oh M.C.

    2015-06-01

    Full Text Available The influence of surface heat treatment using laser radiation on the fatigue strength and corresponding microstructural evolution of AISI 4140 alloy steel was investigated in this research. The AISI 4140 alloy steel was radiated by a diode laser to give surface temperatures in the range between 600 and 800°C, and subsequently underwent vibration peening. The fatigue behavior of surface-treated specimens was examined using a giga-cycle ultrasonic fatigue test, and it was compared with that of non-treated and only-peened specimens. Fatigue fractured surfaces and microstructural evolution with respect to the laser treatment temperatures were investigated using an optical microscope. Hardness distribution was measured using Vickers micro-hardness. Higher laser temperature resulted in higher fatigue strength, attributed to the phase transformation.

  16. Multimodal imaging documentation of rapid evolution of retinal changes in handheld laser-induced maculopathy.

    Science.gov (United States)

    Dhrami-Gavazi, Elona; Lee, Winston; Balaratnasingam, Chandrakumar; Kayserman, Larisa; Yannuzzi, Lawrence A; Freund, K Bailey

    2015-01-01

    To use multimodal imaging to document the relatively rapid clinical evolution of handheld laser-induced maculopathy (HLIM). To demonstrate that inadvertent ocular injury can result from devices mislabeled with respect to their power specifications. The clinical course of a 17-year-old male who sustained self-inflicted, central macular damage from a 20-25 s direct stare at a red-spectrum, handheld laser pointer ordered from an internet retailer is provided. Retrospective review of multimodal imaging that includes fundus photography, fluorescein angiography, MultiColor reflectance, eye-tracked spectral domain optical coherence tomography (SD-OCT), fundus autofluorescence, and microperimetry is used to describe the evolving clinical manifestations of HLIM in the first 3 months. Curvilinear bands of dense hyperreflectivity extending from the outer retina and following the Henle fibers were seen on SD-OCT immediately after injury. This characteristic appearance had largely resolved by 2 weeks. There was significant non-uniformity in the morphological characteristics of HLIM lesions between autofluorescence and reflectance images. The pattern of lesion evolution was also significantly different between imaging modalities. Analysis of the laser device showed its wavelength to be correctly listed, but the power was found to be 102.5-105 mW, as opposed to the laser -induced maculopathy, this finding can undergo rapid resolution in the span of several days. In the absence of this finding, other multimodal imaging clues and a careful history may aid in recognizing this diagnosis. A greater awareness regarding inaccurate labeling on some of these devices could help reduce the frequency of this preventable entity.

  17. Rapid heat treatment for anatase conversion of titania nanotube orthopedic surfaces

    Science.gov (United States)

    Bhosle, Sachin M.; Friedrich, Craig R.

    2017-10-01

    The amorphous to anatase transformation of anodized nanotubular titania surfaces has been studied by x-ray diffraction and transmission electron microscopy (TEM). A more rapid heat treatment for conversion of amorphous to crystalline anatase favorable for orthopedic implant applications was demonstrated. Nanotube titania surfaces were fabricated by electrochemical anodization of Ti6Al4V in an electrolyte containing 0.2 wt% NH4F, 60% ethylene glycol and 40% deionized water. The resulting surfaces were systematically heat treated in air with isochronal and isothermal experiments to study the temperature and time dependent transformation respectively. Energy dispersive spectroscopy shows that the anatase phase transformation of TiO2 in the as-anodized amorphous nanotube layer can be achieved in as little as 5 min at 350 °C in contrast to reports of higher temperature and much longer time. Crystallinity analysis at different temperatures and times yield transformation rate coefficients and activation energy for crystalline anatase coalescence. TEM confirms the (101) TiO2 presence within the nanotubes. These results confirm that for applications where amorphous titania nanotube surfaces are converted to crystalline anatase, a 5 min production flow-through heating process could be used instead of a 3 h batch process, reducing time, cost, and complexity.

  18. Isotropic Heating of Galaxy Cluster Cores via Rapidly Reorienting Active Galactic Nucleus Jets

    Science.gov (United States)

    Babul, Arif; Sharma, Prateek; Reynolds, Christopher S.

    2013-05-01

    Active galactic nucleus (AGN) jets carry more than sufficient energy to stave off catastrophic cooling of the intracluster medium (ICM) in the cores of cool-core clusters. However, in order to prevent catastrophic cooling, the ICM must be heated in a near-isotropic fashion and narrow bipolar jets with P jet = 1044 - 45 erg s-1, typical of radio AGNs at cluster centers, are inefficient in heating the gas in the transverse direction to the jets. We argue that due to existent conditions in cluster cores, the supermassive black holes (SMBHs) will, in addition to accreting gas via radiatively inefficient flows, experience short stochastic episodes of enhanced accretion via thin disks. In general, the orientation of these accretion disks will be misaligned with the spin axis of the black holes (BHs) and the ensuing torques will cause the BH's spin axis (and therefore the jet axis) to slew and rapidly change direction. This model not only explains recent observations showing successive generations of jet-lobes-bubbles in individual cool-core clusters that are offset from each other in the angular direction with respect to the cluster center, but also shows that AGN jets can heat the cluster core nearly isotropically on the gas cooling timescale. Our model does require that the SMBHs at the centers of cool-core clusters be spinning relatively slowly. Torques from individual misaligned disks are ineffective at tilting rapidly spinning BHs by more than a few degrees. Additionally, since SMBHs that host thin accretion disks will manifest as quasars, we predict that roughly 1-2 rich clusters within z < 0.5 should have quasars at their centers.

  19. Human cadaver retina model for retinal heating during corneal surgery with a femtosecond laser

    Science.gov (United States)

    Sun, Hui; Fan, Zhongwei; Yun, Jin; Zhao, Tianzhuo; Yan, Ying; Kurtz, Ron M.; Juhasz, Tibor

    2014-02-01

    Femtosecond lasers are widely used in everyday clinical procedures to perform minimally invasive corneal refractive surgery. The intralase femtosecond laser (AMO Corp. Santa Ana, CA) is a common example of such a laser. In the present study a numerical simulation was developed to quantify the temperature rise in the retina during femtosecond intracorneal surgery. Also, ex-vivo retinal heating due to laser irradiation was measured with an infrared thermal camera (Fluke Corp. Everett, WA) as a validation of the simulation. A computer simulation was developed using Comsol Multiphysics to calculate the temperature rise in the cadaver retina during femtosecond laser corneal surgery. The simulation showed a temperature rise of less than 0.3 degrees for realistic pulse energies for the various repetition rates. Human cadaver retinas were irradiated with a 150 kHz Intralase femtosecond laser and the temperature rise was measured withan infrared thermal camera. Thermal camera measurements are in agreement with the simulation. During routine femtosecond laser corneal surgery with normal clinical parameters, the temperature rise is well beneath the threshold for retina damage. The simulation predictions are in agreement with thermal measurements providing a level of experimental validation.

  20. Heat generation above break-even from laser-induced fusion in ultra-dense deuterium

    Science.gov (United States)

    Holmlid, Leif

    2015-08-01

    Previous results from laser-induced processes in ultra-dense deuterium D(0) give conclusive evidence for ejection of neutral massive particles with energy >10 MeV u-1. Such particles can only be formed from nuclear processes like nuclear fusion at the low laser intensity used. Heat generation is of interest for future fusion energy applications and has now been measured by a small copper (Cu) cylinder surrounding the laser target. The temperature rise of the Cu cylinder is measured with an NTC resistor during around 5000 laser shots per measured point. No heating in the apparatus or the gas feed is normally used. The fusion process is suboptimal relative to previously published studies by a factor of around 10. The small neutral particles HN(0) of ultra-dense hydrogen (size of a few pm) escape with a substantial fraction of the energy. Heat loss to the D2 gas (at deuterium as fusion fuel. With a slightly different setup, a thermal gain of 2 is reached, thus clearly above break-even for all neutronicity values possible. Also including the large kinetic energy which is directly measured for MeV particles leaving through a small opening gives a gain of 2.3. Taking into account the lower efficiency now due to the suboptimal fusion process, previous studies indicate a gain of at least 20 during long periods.

  1. Photoactivation of neurons by laser-generated local heating

    CERN Document Server

    Migliori, Benjamin; Kristan, William

    2012-01-01

    We present a method for achieving temporally and spatially precise photoactivation of neurons without the need for genetic expression of photosensitive proteins. Our method depends upon conduction of thermal energy via absorption by a dye or carbon particles and does not require the presence of voltage-gated channels to create transmembrane currents. We demonstrate photothermal initiation of action potentials in Hirudo verbana neurons and of transmembrane currents in Xenopus oocytes. Thermal energy is delivered by focused 50 ms, 650 nm laser pulses with total pulse energies between 250 and 3500 \\muJ. We document an optical delivery system for targeting specific neurons that can be expanded for multiple target sites. Our method achieves photoactivation reliably (70 - 90% of attempts) and can issue multiple pulses (6-9) with minimal changes to cellular properties as measured by intracellular recording. Direct photoactivation presents a significant step towards all-optical analysis of neural circuits in animals ...

  2. Spectroscopic models for laser-heated silicon and copper nanoparticles

    Science.gov (United States)

    Daun, Kyle; Menser, Jan; Mansmann, Raphael; Moghaddam, Sina Talabi; Dreier, Thomas; Schulz, Christof

    2017-08-01

    Interpreting laser-induced incandescence (LII) measurements on aerosolized nanoparticles requires a spectroscopic model that relates the measured spectral incandescence to the temperature of the nanoparticles. We present spectroscopic models for molten silicon and copper nanoparticles, which are evaluated through extinction and incandescence measurements on nanoaerosols. Measurements on molten silicon nanoparticles are consistent with the Drude theory in the Rayleigh limit of Mie theory. The copper nanoparticles were initially assumed to coalesce into spheres, but the observed spectral incandescence does not show a surface plasmon polariton (SPP) peak in the vicinity of 600 nm expected of spheres. A simulation based on the discrete dipole approximation (DDA) suggests that this effect could be explained by the structure of the copper aggregates.

  3. Heat generation above break-even from laser-induced fusion in ultra-dense deuterium

    Directory of Open Access Journals (Sweden)

    Leif Holmlid

    2015-08-01

    Full Text Available Previous results from laser-induced processes in ultra-dense deuterium D(0 give conclusive evidence for ejection of neutral massive particles with energy >10 MeV u−1. Such particles can only be formed from nuclear processes like nuclear fusion at the low laser intensity used. Heat generation is of interest for future fusion energy applications and has now been measured by a small copper (Cu cylinder surrounding the laser target. The temperature rise of the Cu cylinder is measured with an NTC resistor during around 5000 laser shots per measured point. No heating in the apparatus or the gas feed is normally used. The fusion process is suboptimal relative to previously published studies by a factor of around 10. The small neutral particles HN(0 of ultra-dense hydrogen (size of a few pm escape with a substantial fraction of the energy. Heat loss to the D2 gas (at <1 mbar pressure is measured and compensated for under various conditions. Heat release of a few W is observed, at up to 50% higher energy than the total laser input thus a gain of 1.5. This is uniquely high for the use of deuterium as fusion fuel. With a slightly different setup, a thermal gain of 2 is reached, thus clearly above break-even for all neutronicity values possible. Also including the large kinetic energy which is directly measured for MeV particles leaving through a small opening gives a gain of 2.3. Taking into account the lower efficiency now due to the suboptimal fusion process, previous studies indicate a gain of at least 20 during long periods.

  4. Investigating the laser heating of underdense plasmas at conditions relevant to MagLIF

    Science.gov (United States)

    Harvey-Thompson, Adam

    2015-11-01

    The magnetized Liner Inertial Fusion (MagLIF) scheme has achieved thermonuclear fusion yields on Sandia's Z Facility by imploding a cylindrical liner filled with D2 fuel that is preheated with a multi-kJ laser and pre-magnetized with an axial field Bz = 10 T. The challenge of fuel preheating in MagLIF is to deposit several kJ's of energy into an underdense (ne/ncritdynamics of a MagLIF implosion and stagnation, but also to validate magnetized transport models and better understand the physics of laser propagation in magnetized plasmas. In this talk, we present data and analysis of several experiments conducted at OMEGA-EP and at Z to investigate laser propagation and plasma heating in underdense D2 plasmas under a range of conditions, including densities (ne = 0.05-0.1 nc) and magnetization parmaters (ωceτe ~ 0-10). The results show differences in the electron temperature of the heated plasma and the velocity of the laser burn wave with and without an applied magnetic field. We will show comparisons of these experimental results to 2D and 3D HYDRA simulations, which show that the effect of the magnetic field on the electron thermal conduction needs to be taken into account when modeling laser preheat. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the National Nuclear Security Administration under Contract No. DE-AC04-94AL85000.

  5. Rapid elemental analysis and provenance study of Blumea balsamifera DC using laser-induced breakdown spectroscopy.

    Science.gov (United States)

    Liu, Xiaona; Zhang, Qiao; Wu, Zhisheng; Shi, Xinyuan; Zhao, Na; Qiao, Yanjiang

    2014-12-31

    Laser-induced breakdown spectroscopy (LIBS) was applied to perform a rapid elemental analysis and provenance study of Blumea balsamifera DC. Principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were implemented to exploit the multivariate nature of the LIBS data. Scores and loadings of computed principal components visually illustrated the differing spectral data. The PLS-DA algorithm showed good classification performance. The PLS-DA model using complete spectra as input variables had similar discrimination performance to using selected spectral lines as input variables. The down-selection of spectral lines was specifically focused on the major elements of B. balsamifera samples. Results indicated that LIBS could be used to rapidly analyze elements and to perform provenance study of B. balsamifera.

  6. Hydroxyapatite Coatings on High Nitrogen Stainless Steel by Laser Rapid Manufacturing

    Science.gov (United States)

    Das, Ashish; Shukla, Mukul

    2017-11-01

    In this research, the laser rapid manufacturing (LRM) additive manufacturing process was used to deposit multifunctional hydroxyapatite (HAP) coatings on high nitrogen stainless steel. LRM overcomes the limitations of conventional coating processes by producing coatings with metallurgical bond, osseointegration, and infection inhibition properties. The microstructure, microhardness, antibacterial efficacy, and bioactivity of the coatings were investigated. The microstructure studies established that the coatings consist of austenite dendrites with HAP and some reaction products primarily occurring in the inter-dendritic regions. A Vickers microhardness test confirmed the hardness values of deposited HAP coatings to be higher than those of the bare 254SS samples, while a fluorescence activated cell sorting test confirmed their superior antibacterial properties as compared with pristine samples. The coated samples immersed in simulated body fluid showed rapid apatite forming ability. The results obtained in this research signify the potential application of the LRM process in synthesizing multifunctional orthopaedic coatings.

  7. Rapid Elemental Analysis and Provenance Study of Blumea balsamifera DC Using Laser-Induced Breakdown Spectroscopy

    Directory of Open Access Journals (Sweden)

    Xiaona Liu

    2014-12-01

    Full Text Available Laser-induced breakdown spectroscopy (LIBS was applied to perform a rapid elemental analysis and provenance study of Blumea balsamifera DC. Principal component analysis (PCA and partial least squares discriminant analysis (PLS-DA were implemented to exploit the multivariate nature of the LIBS data. Scores and loadings of computed principal components visually illustrated the differing spectral data. The PLS-DA algorithm showed good classification performance. The PLS-DA model using complete spectra as input variables had similar discrimination performance to using selected spectral lines as input variables. The down-selection of spectral lines was specifically focused on the major elements of B. balsamifera samples. Results indicated that LIBS could be used to rapidly analyze elements and to perform provenance study of B. balsamifera.

  8. Enhanced Thermo-Optical Switching of Paraffin-Wax Composite Spots under Laser Heating.

    Science.gov (United States)

    Said, Asmaa; Salah, Abeer; Fattah, Gamal Abdel

    2017-05-12

    Thermo-optical switches are of particular significance in communications networks where increasingly high switching speeds are required. Phase change materials (PCMs), in particular those based on paraffin wax, provide wealth of exciting applications with unusual thermally-induced switching properties, only limited by paraffin's rather low thermal conductivity. In this paper, the use of different carbon fillers as thermal conductivity enhancers for paraffin has been investigated, and a novel structure based on spot of paraffin wax as a thermo-optic switch is presented. Thermo-optical switching parameters are enhanced with the addition of graphite and graphene, due to the extreme thermal conductivity of the carbon fillers. Differential Scanning Calorimetry (DSC) and Scanning electron microscope (SEM) are performed on paraffin wax composites, and specific heat capacities are calculated based on DSC measurements. Thermo-optical switching based on transmission is measured as a function of the host concentration under conventional electric heating and laser heating of paraffin-carbon fillers composites. Further enhancements in thermo-optical switching parameters are studied under Nd:YAG laser heating. This novel structure can be used in future networks with huge bandwidth requirements and electric noise free remote aerial laser switching applications.

  9. Model of a laser heated plasma interacting with walls arising in laser keyhole welding

    Science.gov (United States)

    Tix, C.; Simon, G.

    1994-07-01

    In laser welding with laser intensities of approximately 1011 W/m2, a hole, called a keyhole, is formed in the material. In this keyhole a plasma is detected, which is characterized by high pressure as well as being influenced by the boundary of the keyhole. Experimental data on plasma parameters are rare and difficult to obtain [W. Sokolowski, G. Herziger, and E. Beyer, in High Power Lasers and Laser Machining Technology, edited by A. Quenzer, SPIE Proc. Vol. 1132 (SPIE, Bellingham, WA, 1989), pp. 288-295]. In a previous paper [C. Tix and G. Simon, J. Phys. D 26, 2066 (1993)] we considered just a simple plasma model without excited states and with constant ion-neutral-atom temperature. Therefore we neglected radiative transport of excitations and underestimated the ion-neutral-atom temperature and the ionization rate. Here we extend our previous model for a continuous CO2 laser and iron and take into account radiative transfer of excitations and a variable ion-neutral-atom temperature. We consider singly charged ions, electrons, and three excitation states of neutral atoms. The plasma is divided in plasma bulk, presheath, and sheath. The transport equations are solved with boundary conditions mainly determined through the appearance of walls. Some effort is made to clarify the energy transport mechanism from the laser beam into the material. Dependent on the incident laser power, the mean electron temperature and density are obtained to be 1.0-1.3 eV and 2.5×1023-3×1023 m-3. Radiative transport of excitations does not contribute significantly to the energy transport.

  10. Rapid laser annealing of Cu(In,Ga)Se2 thin films by using a continuous wave Nd:YAG laser (λ0= 532 nm)

    Science.gov (United States)

    Kim, Nam-Hoon; Ko, Pil Ju; Cho, Geum-Bae; Park, Chan Il

    2017-04-01

    Rapid laser annealing of a Cu(In,Ga)Se2 (CIGS) thin film absorber was proposed and demonstrated using a continuous 532-nm Nd:YAG laser, following sputtering with Cu0.9In0.7Ga0.3Se2 target, because the conventional annealing temperature for improving the crystallinity of CIGS thin films is higher than the decomposition temperature of a typical flexible polymer substrate. When the laser optical power was incrementally increased over the range from 2.00 to 3.00 W, for 200 s, XRD patterns showed the formation of CIGS chalcopyrite (112), (220/204), and (312/116) phases in the laser-annealed CIGS thin films, at laser optical powers of 2.75 and 3.00 W. The band gaps of these laser-annealed CIGS thin films varied from 1.45 to 1.83 eV and depended on the laser optical power. The relative mean absorbance of the laser-annealed CIGS thin films was 1.806, suggesting that approximately 98.44% of the incident photons were observed by the 600-nm-thick film in the visible spectral region. Conductivity type varied with changes in the laser optical power. The resistivities of the laser-annealed CIGS thin films were of order of 10-3 - 101 Ω-cm.

  11. Testing relativity again, laser, laser, laser, laser

    NARCIS (Netherlands)

    Einstein, A.

    2015-01-01

    laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser, laser,

  12. Phonons spreading from laser-heated gold nanoparticle array accelerate diffusion of excitons in an underlying polythiophene thin film.

    Science.gov (United States)

    Rais, David; Menšík, Miroslav; Paruzel, Bartosz; Kurunthu, Dharmalingam; Pfleger, Jiří

    2017-04-19

    Localized surface plasmon (LSP) photophysical phenomena occurring in metal nanostructures are often presented as a method to effectively couple light into photovoltaic devices of sub-wavelength-scale thickness. However, the excitation of LSP is also associated with rapid energy dissipation leading to local heating, which affects the excitation energy pathway. We studied a system consisting of a planar gold nanoparticle (AuNP) array deposited at the surface of a semiconducting polymer thin film (P3HT). We observed heat transfer from laser pulse excited AuNPs into the P3HT, which was evidenced as a long-living thermochromic effect on transient optical absorption. By modeling of the ultrafast kinetics of exciton population evolution, we determined that their decay was caused by their mutual annihilation. The decay rate was controlled by a phonon-assisted one-dimensional diffusion mechanism with a diffusion constant of 2.2 nm2 ps-1. The transferred heat resulted in an increase of the diffusion constant by a factor of almost 2, compared to the control system of P3HT without AuNPs. These results are of practical use for the design of plasmon-enhanced optoelectronic devices.

  13. Ultrafast electron diffraction from non-equilibrium phonons in femtosecond laser heated Au films

    Energy Technology Data Exchange (ETDEWEB)

    Chase, T. [Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Department of Applied Physics, Stanford University, Stanford, California 94305 (United States); Trigo, M.; Reid, A. H.; Dürr, H. A. [Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Li, R.; Vecchione, T.; Shen, X.; Weathersby, S.; Coffee, R.; Hartmann, N.; Wang, X. J. [SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Reis, D. A. [Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Department of Applied Physics, Stanford University, Stanford, California 94305 (United States); PULSE Institute, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States)

    2016-01-25

    We use ultrafast electron diffraction to detect the temporal evolution of non-equilibrium phonons in femtosecond laser-excited ultrathin single-crystalline gold films. From the time-dependence of the Debye-Waller factor, we extract a 4.7 ps time-constant for the increase in mean-square atomic displacements. The observed increase in the diffuse scattering intensity demonstrates that the energy transfer from laser-heated electrons to phonon modes near the X and K points in the Au fcc Brillouin zone proceeds with timescales of 2.3 and 2.9 ps, respectively, faster than the Debye-Waller average mean-square displacement.

  14. A laser ion source with a thin ohmic-heating ionizer for the TIARA-ISOL

    CERN Document Server

    Koizumi, M; Oshima, M; Sekine, T; Wakui, T; Jin, W G; Katsuragawa, H; Miyatake, H; Ishida, Y

    2003-01-01

    An ohmic-heating laser ion source with a thin ionizer of thickness of 30 mu m has been developed for the TIARA-ISOL. It can form an electric field of 4-5 V/cm inside the ionizer. The properties of the laser ion source were tested on- and off-line with aluminum isotopes. The FWHM of the time distribution of the bunched photoions from the ion source was about 4 mu s for sup 2 sup 7 Al. In on-line experiment, a photoionization efficiency of about 0.1% for sup 2 sup 5 Al was obtained.

  15. Heat transfer model of semi-transparent ceramics undergoing laser-assisted machining

    Energy Technology Data Exchange (ETDEWEB)

    Pfefferkorn, F.E. [University of Wisconsin-Madison (United States). Department of Mechanical Engineering; Incropera, F.P. [University of Notre Dame, IN (United States). College of Engineering; Yung C. Shin [Purdue University, West Lafayette, IN (United States). School of Mechanical Engineering

    2005-05-01

    A three-dimensional, unsteady heat transfer model has been developed for predicting the temperature field in partially-stabilized zirconia (PSZ) undergoing laser-assisted machining. The semi-transparent PSZ is treated as optically thick within a spectral band from approximately 0.5 to 8 {mu}m. After comparing the diffusion approximation and the discrete ordinates method for predicting internal radiative transfer, suitability of the diffusion approximation is established from a comparison of model predictions with surface temperature measurements. The temperature predictions are in good agreement with measured values during machining. Parametric calculations reveal that laser power and feedrate have the greatest effect on machining temperatures. (author)

  16. Selective laser sintering: application of a rapid prototyping method in craniomaxillofacial reconstructive surgery.

    Science.gov (United States)

    Aung, S C; Tan, B K; Foo, C L; Lee, S T

    1999-09-01

    Advances in technology have benefited the medical world in many ways and a new generation of computed tomography (CT) scanners and three-dimensional (3-D) model making rapid prototyping systems (RPS) have taken craniofacial surgical planning and management to new heights. With the development of new rapid prototyping systems and the improvements in CT scan technology, such as the helical scanner, biomedical modelling has improved considerably and accurate 3-D models can now be fabricated to allow surgeons to visualise and physically handle a 3-D model on which simulation surgery can be performed. The principle behind this technology is to first acquire digital data (CT scan data) which is then imported to the RPS to fabricate fine layers or cuts of the model which are gradually built up to form the 3-D models. Either liquid resin or nylon powder or special paper may be used to make these models using the various RPS available today. Selective laser sintering (SLS), which employs a CO2 laser beam to solidify special nylon powder and build up the model in layers is described in this case report, where a 23-year old Chinese female with panfacial fracture and a skull defect benefited from SLS biomodelling in the preoperative workup.

  17. Instrumentation pour la spectroscopie laser sur faisceau d'ions rapides

    Science.gov (United States)

    Bazin, Marc

    Devant l'emergence des technologies exploitant l'infiniment petit, la spectroscopie atomique et moleculaire devient de plus en plus incontournable pour comprendre precisement les mecanismes quantiques impliques dans l'interaction des molecules. C'est le cas notamment de la nanotechnologie, de la dynamique reactionnelle des gaz a effet de serre ou simplement de l'identification des molecules constituant certains objets de l'astrophysique. Bien qu'un travail considerable soit deja accompli pour comprendre la dissociation ou la formation des molecules simples, il reste a vaincre la complexite des mecanismes impliques lorsque les molecules possedent plus de trois noyaux. Parmi les rares techniques de spectroscopie a tres haute resolution (jusqu'a la structure hyperfine), la spectroscopie laser sur faisceaux d'ions rapides est une methode experimentale eprouvee depuis trois decennies environ. Cette methode spectroscopique fournit des resultats comptant parmi les meilleurs pour obtenir des constantes moleculaires precises et permettre la reduction du spectre moleculaire. Une particularite remarquable de notre instrument est la possibilite d'enregistrer le signal de fragmentation moleculaire par laser via les etats de predissociation de la molecule etudiee. Notre contribution a ete d'ameliorer et de moderniser l'equipement existant. Nous avons augmente la resolution spectrale de notre instrument. Nous avons atteint notre principal objectif, a savoir, la possibilite d'acquerir des spectres selon deux modes : par detection du signal synchronisee sur le faisceau laser module en frequence ou par detection du signal directement par comptage. Cette derniere methode est une premiere sur ce type d'instrument et son principal interet a ete d'obtenir une meilleure mesure de l'elargissement de raie. Nous sommes parvenus a mettre clairement en evidence l'elargissement de raie avec la puissance laser en utilisant la methode de detection par comptage direct. La fluorescence induite par

  18. Electron heating by intense short-pulse lasers propagating through near-critical plasmas

    Science.gov (United States)

    Debayle, A.; Mollica, F.; Vauzour, B.; Wan, Y.; Flacco, A.; Malka, V.; Davoine, X.; Gremillet, L.

    2017-12-01

    We investigate the electron heating induced by a relativistic-intensity laser pulse propagating through a near-critical plasma. Using particle-in-cell simulations, we show that a specific interaction regime sets in when, due to the energy depletion caused by the plasma wakefield, the laser front profile has steepened to the point of having a length scale close to the laser wavelength. Wave breaking and phase mixing have then occurred, giving rise to a relativistically hot electron population following the laser pulse. This hot electron flow is dense enough to neutralize the cold bulk electrons during their backward acceleration by the wakefield. This neutralization mechanism delays, but does not prevent the breaking of the wakefield: the resulting phase mixing converts the large kinetic energy of the backward-flowing electrons into thermal energy greatly exceeding the conventional ponderomotive scaling at laser intensities > {10}21 {{{W}}{cm}}-2 and gas densities around 10% of the critical density. We develop a semi-numerical model, based on the Akhiezer–Polovin equations, which correctly reproduces the particle-in-cell-predicted electron thermal energies over a broad parameter range. Given this good agreement, we propose a criterion for full laser absorption that includes field-induced ionization. Finally, we show that our predictions still hold in a two-dimensional geometry using a realistic gas profile.

  19. A computational model for heterogeneous heating during pulsed laser irradiation of polymers doped with light-absorbing microparticles

    DEFF Research Database (Denmark)

    Marla, Deepak; Zhang, Yang; Jabbaribehnam, Mirmasoud

    2016-01-01

    Doping of polymers with light-absorbing microparticles to increase their optical properties is a commonly used pre-treatment technique in laser processing of polymers. The presence of these particles plays an important role during laser heating of the polymer that influences its surface character......Doping of polymers with light-absorbing microparticles to increase their optical properties is a commonly used pre-treatment technique in laser processing of polymers. The presence of these particles plays an important role during laser heating of the polymer that influences its surface...... characteristics. This work presents a study based on a computational model of laser heating of polymer doped with light-absorbing microparticles accounting for the heterogeneous nature of heating. The work aims at gaining a fundamental insight into the nature of the heating process and to understand the role...... of microparticles. The results suggest that apart from the laser intensity and pulse duration, the properties of the microparticles including their size and distribution also play an important role during the laser heating of polymers....

  20. Development and Demonstration of a High Efficiency, Rapid Heating, Low NOx Alternative to Conventional Heating of Round Steel Shapes, Steel Substrate (Strip) and Coil Box Transfer Bars

    Energy Technology Data Exchange (ETDEWEB)

    Kurek, Harry; Wagner, John

    2010-01-25

    Direct Flame Impingement involves the use of an array of very high-velocity flame jets impinging on a work piece to rapidly heat the work piece. The predominant mode of heat transfer is convection. Because of the locally high rate of heat transfer at the surface of the work piece, the refractory walls and exhaust gases of a DFI furnace are significantly cooler than in conventional radiant heating furnaces, resulting in high thermal efficiency and low NOx emissions. A DFI furnace is composed of a successive arrangement of heating modules through or by which the work piece is conveyed, and can be configured for square, round, flat, and curved metal shapes (e.g., billets, tubes, flat bars, and coiled bars) in single- or multi-stranded applications.

  1. CO sub 2 laser-heated diamond-anvil cell methodology revisited

    CERN Document Server

    Hearne, G; Zhao, J

    2002-01-01

    A description is given of CO sub 2 laser heating system for attaining high temperatures at pressure in a diamond-anvil cell (DAC). The main purpose of this paper is to demonstrate that a relatively inexpensive set-up, perhaps affordable to many high-pressure laboratories, may be commissioned for laser-heated DAC experiments to achieve comparable extreme P-T conditions to those attained with more sophisticated stations documented in the literature. A novel idea of using the analogue output of a CCD camera to estimate the peak temperature and map the temperature distribution across the hot-spot has been tested. In an additional initial experiment on cubic zirconia (c-ZrO sub 2) we present evidence from a Raman characterization of the sample that temperatures exceeding 4000 K have been obtained at pressure in the DAC.

  2. Effect of pressure relaxation during the laser heating and electron-ion relaxation stages

    Energy Technology Data Exchange (ETDEWEB)

    Chimier, B.; Tikhonchuk, V.T.; Hallo, L. [Univ Bordeaux 1, CEA, CNRS, CELIA, UMR 5107, 33 - Talence (France)

    2008-09-15

    The multi-phase equation of state by Bushman et al. (Sov. Tech. Rev. 5:1-44, 2008) is modified to describe states with different electron and ion temperatures and it is applied to the non-equilibrium evolution of an aluminum sample heated by a subpicosecond laser pulse. The sample evolution is described by the two-temperature model for the electron and ion temperatures, while the pressure and density are described by a simplified relaxation equation. The pressure relaxation in the heating stage reduces the binding energy and facilitates the electron-driven ablation. The model is applied to estimate the ablation depth of an Al target irradiated by a subpicosecond laser pulse. It improves the agreement with the experimental data and provides a new explanation of the ablation process. (authors)

  3. Effect of low-level laser therapy after rapid maxillary expansion: a clinical investigation.

    Science.gov (United States)

    Garcia, Valentin Javier; Arnabat, J; Comesaña, Rafael; Kasem, Khaled; Ustrell, Josep Maria; Pasetto, Stefano; Segura, Oscar Pozuelo; ManzanaresCéspedes, Maria Cristina; Carvalho-Lobato, Patricia

    2016-08-01

    To evaluate the effectiveness low-level laser therapy (LLLT) on the repair of the mid palatal suture, after rapid maxillary expansion (RME). A single-operator, randomized single-blind placebo-controlled study was performed at the Orthodontic Department at the Dental Hospital of Bellvitge. Barcelona University, Hospitalet de Llobregat, Spain. Thirty-nine children (range 6-12 years old), completed RME and were randomized to receive active LLLT (n = 20) or placebo (n = 19). The laser parameters and dose were 660 nm, 100 mW, CW, InGaAlP laser, illuminated area 0.26 cm(2), 332 mW/cm(2), 60 s to four points along midpalatal suture, and 30 s to a point each side of the suture. A total of seven applications were made on days 1, 7, 14, 28, 42, 56, and 70 of the retention phase RME. A cone beam computed tomography (CBCT) scan was carried out on the day of the first laser treatment, and at day 75, a second CBCT scan was performed. Two radiologists synchronized the slices of two scans to be assessed. P = 0.05 was considered to be statistically significant. At day 75 of the suture, the irradiated patients presented a greater percentage of approximate zones in the anterior (p = 0.008) and posterior (p = 0.001) superior suture-and less approximation in the posterior superior suture (p = 0.040)-than the placebo group. LLLT appears to stimulate the repair process during retention phase after RME.

  4. Bounds on Heat Transport in Rapidly Rotating Rayleigh-B\\'{e}nard Convection

    CERN Document Server

    Grooms, Ian

    2014-01-01

    The heat transport in rotating Rayleigh-B\\'enard convection is considered in the limit of rapid rotation (small Ekman number $E$) and strong thermal forcing (large Rayleigh number $Ra$). The analysis proceeds from a set of asymptotically reduced equations appropriate for rotationally constrained dynamics; the conjectured range of validity for these equations is $Ra \\lesssim E^{-8/5}$. A rigorous bound on heat transport of $Nu \\le 20.56Ra^3E^4$ is derived in the limit of infinite Prandtl number using the background method. We demonstrate that the exponent in this bound cannot be improved on using a piece-wise monotonic background temperature profile like the one used here. This is true for finite Prandtl numbers as well, i.e. $Nu \\lesssim Ra^3$ is the best upper bound for this particular setup of the background method. The feature that obstructs the availability of a better bound in this case is the appearance of small-scale thermal plumes emanating from (or entering) the thermal boundary layer.

  5. Incremental heating of Bishop Tuff sanidine reveals preeruptive radiogenic Ar and rapid remobilization from cold storage

    Science.gov (United States)

    Andersen, Nathan L.; Jicha, Brian R.; Singer, Brad S.; Hildreth, Wes

    2017-11-01

    Accurate and precise ages of large silicic eruptions are critical to calibrating the geologic timescale and gauging the tempo of changes in climate, biologic evolution, and magmatic processes throughout Earth history. The conventional approach to dating these eruptive products using the 40Ar/39Ar method is to fuse dozens of individual feldspar crystals. However, dispersion of fusion dates is common and interpretation is complicated by increasingly precise data obtained via multicollector mass spectrometry. Incremental heating of 49 individual Bishop Tuff (BT) sanidine crystals produces 40Ar/39Ar dates with reduced dispersion, yet we find a 16-ky range of plateau dates that is not attributable to excess Ar. We interpret this dispersion to reflect cooling of the magma reservoir margins below ˜475 °C, accumulation of radiogenic Ar, and rapid preeruption remobilization. Accordingly, these data elucidate the recycling of subsolidus material into voluminous rhyolite magma reservoirs and the effect of preeruptive magmatic processes on the 40Ar/39Ar system. The youngest sanidine dates, likely the most representative of the BT eruption age, yield a weighted mean of 764.8 ± 0.3/0.6 ka (2σ analytical/full uncertainty) indicating eruption only ˜7 ky following the Matuyama‑Brunhes magnetic polarity reversal. Single-crystal incremental heating provides leverage with which to interpret complex populations of 40Ar/39Ar sanidine and U-Pb zircon dates and a substantially improved capability to resolve the timing and causal relationship of events in the geologic record.

  6. Local modification of GaAs nanowires induced by laser heating

    Energy Technology Data Exchange (ETDEWEB)

    Yazji, S; Zardo, I; Soini, M; Fontcuberta i Morral, A; Abstreiter, G [Walter Schottky Institut and Physik Department, Technische Universitaet Muenchen, Am Coulombwall 4, D-85748 Garching (Germany); Postorino, P, E-mail: ilaria.zardo@wsi.tum.de [Dipartimento di Fisica, Universita di Roma Sapienza, Piazzale Aldo Moro 5, I-00185 Roma (Italy)

    2011-08-12

    GaAs nanowires were heated locally under ambient air conditions by a focused laser beam which led to oxidation and formation of crystalline arsenic on the nanowire surface. Atomic force microscopy, photoluminescence and Raman spectroscopy experiments were performed on the same single GaAs nanowires in order to correlate their structural and optical properties. We show that the local changes of the nanowires act as a barrier for thermal transport which is of interest for thermoelectric applications.

  7. FATIGUE BEHAVIOR OF PEARLITIC S.G. CAST IRONS AFTER LASER SURFACE HEAT TREATMENTS

    OpenAIRE

    Guan, Y.; Pantelis, D.; Chambolle, D.; Parent-Simonin, S.; Poupeau, Ph.

    1991-01-01

    The laser transformation hardening does not improve the fatigue resistance of two pearlitic S.G. cast irons, using as surface preparation BN coating, sandblasting or phosphatation. On the treated surface, the initial pearlite is transformed into martensite. In the treated layer, further under the treated surface, a martensitic microstructure with traces of incompletely dissolved cementite can be observed. A bidimensional numerical heat transfer model has been developed for surface transformat...

  8. Heating of solid target in electron refluxing dominated regime with ultra-intense laser

    Science.gov (United States)

    Nakatsutsumi, M.; Kodama, R.; Aglitskiy, Y.; Akli, K. U.; Batani, D.; Baton, S. D.; Beg, F. N.; Benuzzi-Mounaix, A.; Chen, S. N.; Clark, D.; Davies, J. R.; Freeman, R. R.; Fuchs, J.; Green, J. S.; Gregory, C. D.; Guillou, P.; Habara, H.; Heathcote, R.; Hey, D. S.; Highbarger, K.; Jaanimagi, P.; Key, M. H.; Koenig, M.; Krushelnick, K.; Lancaster, K. L.; Loupias, B.; Ma, T.; Macphee, A.; Mackinonn, A. J.; Mima, K.; Morace, A.; Nakamura, H.; Norryes, P. A.; Piazza, D.; Rousseaux, C.; Stephans, R. B.; Storm, M.; Tampo, M.; Theobald, W.; Woerkom, L. V.; Weber, R. L.; Wei, M. S.; Woolsey, N. C.

    2008-05-01

    Propagation of electron beams generated in laser-plasma interactions is strongly influenced by self-induced electrostatic fields at target-vacuum interfaces, resulting the refluxing of electrons. We confirmed the refluxing and propagation of electrons with three different kinds of target configurations; thin-wide foil, thin-narrow foil, and long-wire geometry. Enhancement of target heating, effective guiding and collimation of high density MeV electrons were observed.

  9. Material transport in laser-heated diamond anvil cell melting experiments

    Science.gov (United States)

    Campbell, Andrew J.; Heinz, Dion L.; Davis, Andrew M.

    1992-01-01

    A previously undocumented effect in the laser-heated diamond anvil cell, namely, the transport of molten species through the sample chamber, over distances large compared to the laser beam diameter, is presented. This effect is exploited to determine the melting behavior of high-pressure silicate assemblages of olivine composition. At pressures where beta-spinel is the phase melted, relative strengths of partitioning can be estimated for the incompatible elements studied. Iron was found to partition into the melt from beta-spinel less strongly than calcium, and slightly more strongly than manganese. At higher pressures, where a silicate perovskite/magnesiowuestite assemblage is melted, it is determined that silicate perovskite is the liquidus phase, with iron-rich magnesiowuestite accumulating at the end of the laser-melted stripe.

  10. Cladding single crystal YAG fibers grown by laser heated pedestal growth

    Science.gov (United States)

    Bera, Subhabrata; Nie, Craig D.; Harrington, James A.; Chick, Theresa; Chakrabarty, Ayan; Trembath-Reichert, Stephen; Chapman, James; Rand, Stephen C.

    2016-03-01

    Rare-earth doped single-crystal (SC) Yttrium Aluminum Garnet (YAG) fibers are excellent candidates for high power lasers. These SC fiber optics combine the favorable low Stimulated Brillouin Scattering (SBS) gain coefficient and excellent thermal properties to make them an attractive alternative to glass fiber lasers and amplifiers. Various rare-earth doped SC fibers have been grown using the laser heated pedestal growth (LHPG) technique. Several cladding methods, including in-situ and post-growth cladding techniques, are discussed in this paper. A rod-in-tube approach has been used by to grow a fiber with an Erbium doped SC YAG fiber core inserted in a SC YAG tube. The result is a radial gradient in the distribution of rare-earth ions. Post cladding methods include sol-gel deposited polycrystalline.

  11. Propagation of a laser beam in a time-varying waveguide. [plasma heating for controlled fusion

    Science.gov (United States)

    Chapman, J. M.; Kevorkian, J.

    1978-01-01

    The propagation of an axisymmetric laser beam in a plasma column having a radially parabolic electron density distribution is reported. For the case of an axially uniform waveguide it is found that the basic characteristics of alternating focusing and defocusing beams are maintained. However, the intensity distribution is changed at the foci and outer-beam regions. The features of paraxial beam propagation are discussed with reference to axially varying waveguides. Laser plasma coupling is considered noting the case where laser heating produces a density distribution radially parabolic near the axis and the energy absorbed over the focal length of the plasma is small. It is found that: (1) beam-propagation stability is governed by the relative magnitude of the density fluctuations existing in the axial variation of the waveguides due to laser heating, and (2) for beam propagation in a time-varying waveguide, the global instability of the propagation is a function of the initial fluctuation growth rate as compared to the initial time rate of change in the radial curvature of the waveguide.

  12. Initiation of long, free-standing Z-discharges by CO2 laser gas heating

    Energy Technology Data Exchange (ETDEWEB)

    Nieman, C.; Tauschwitz, A.; Penache, D.; Neff, S.; Knobloch, R.; Birkner, R.; Presura, R.; Hoffmann, D.H.H.; Yu, S.S.; Sharp, W.M.

    2004-04-19

    High current discharge channels can neutralize both current and space charge of very intense ion beams. Therefore they are considered as an interesting alternative for the final focus and beam transport in a heavy ion beam fusion reactor. At the GSI accelerator facility, 50 cm long, stable, free-standing discharge channels with currents in excess of 40 kA in 2 to 25 mbar ammonia (NH{sub 3}) gas are investigated for heavy ion beam transport studies. The discharges are initiated by a CO{sub 2} laser pulse along the channel axis before the discharge is triggered. Resonant absorption of the laser, tuned to the {nu}{sub 2} vibration of the ammonia molecule, causes strong gas heating. Subsequent expansion and rarefaction of the gas prepare the conditions for a stable discharge to fulfill the requirements for ion beam transport. This paper describes the laser-gas interaction and the discharge initiation mechanism. We report on the channel stability and evolution, measured by fast shutter and streak imaging techniques. The rarefaction of the laser heated gas is studied by means of a hydrocode simulation.

  13. Initiation of long, free-standing z discharges by CO2 laser gas heating

    Science.gov (United States)

    Niemann, C.; Tauschwitz, A.; Penache, D.; Neff, S.; Knobloch, R.; Birkner, R.; Presura, R.; Hoffmann, D. H. H.; Yu, S. S.; Sharp, W. M.

    2002-01-01

    High current discharge channels can neutralize both current and space charge of very intense ion beams. Therefore, they are considered an interesting solution for final focus and beam transport in a heavy ion beam fusion reactor. At the Gesellschaft für Schwerionenforschung accelerator facility, 50 cm long, free-standing discharge channels were created in a 60 cm diameter metallic chamber. Discharges with currents of 45 kA in 2 to 25 mbar ammonia (NH3) gas are initiated by a CO2 laser pulse along the channel axis before the capacitor bank is triggered. Resonant absorption of the laser, tuned to the v2 vibration of the ammonia molecule, causes strong gas heating. Subsequent expansion and rarefaction of the gas prepare the conditions for a stable discharge to fulfill the requirements for ion beam transport. The influence of an electric prepulse on the high current discharge was investigated. This article describes the laser-gas interaction and the discharge initiation mechanism. We found that channels are magnetohydrodynamic stable up to currents of 45 kA, measured by fast shutter and streak imaging techniques. The rarefaction of the laser heated gas is studied by means of a one-dimensional Lagrangian fluid code (CYCLOPS) and is identified as the dominant initiation mechanism of the discharge.

  14. Rapid and low-cost fabrication of polystyrene-based molds for PDMS microfluidic devices using a CO2 laser

    KAUST Repository

    Li, Huawei

    2011-11-01

    In this article, we described a rapid and low-cost method to fabricate polystyrene molds for PDMS microfluidic devices using a CO2 laser system. It takes only several minutes to fabricate the polystyrene mold with bump pattern on top of it using a CO2 laser system. The bump pattern can be easily transferred to PDMS and fabricate microchannles as deep as 3μm on PDMS. © (2012) Trans Tech Publications, Switzerland.

  15. Methodology for in situ synchrotron X-ray studies in the laser-heated diamond anvil cell

    DEFF Research Database (Denmark)

    Mezouar, M.; Giampaoli, R.; Garbarino, G.

    2017-01-01

    in the case of elemental tantalum. Preliminary results of a comparison between reflective and refractive optics for high temperature measurements in the laser-heated diamond anvil cell are briefly discussed. Finally, the importance of the size and relative alignment of X-ray and laser beams for quantitative X...

  16. Weldability of titanium sheet for plate type heat exchanger by Nd:YAG laser

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jong Do; Song, Moo Keun [Korea Maritime University, Busan (Korea, Republic of); Kwak, Myung Sub [Daewoo Shipbuilding and Marine Engineering Co., Ltd., Seoul (Korea, Republic of); Kim, Chang Soo [Donghwa Entec, Busan (Korea, Republic of)

    2009-07-01

    Pure titanium and its alloys have excellent corrosion resistance in seawater, high specific strength and creep properties in high temperature. For these reasons, the application is expanded into the field of marine as the heat exchanger plate, marine plant, and so on. Conventional plate type heat exchanger has prevented fluid leakage with gaskets between the plates by mechanical joining method, but gaskets are hardened in high temperature and pressure. Thus, LPG re-condenser which is always in high temperature and pressure, is jointed its plates by welding. Arc weldment has large HAZ and possibility of distortion because of large heat input. And EBW and diffusion bonding make high quality welds, but it should be done in vacuum conditions. Hence, laser welding is applied to get sound beads with small heat input and high aspect ratio in the air. In this study, weld properties of CP titanium were investigated by pulsed and CW Nd:YAG lasers. And welds without porosity, humping, crack, spatter and oxidation were accepted and the best welding conditions were applied to LPG reliquifaction system.

  17. A study of the flow boiling heat transfer in a minichannel for a heated wall with surface texture produced by vibration-assisted laser machining

    Science.gov (United States)

    Piasecka, Magdalena; Strąk, Kinga; Maciejewska, Beata; Grabas, Bogusław

    2016-09-01

    The paper presents results concerning flow boiling heat transfer in a vertical minichannel with a depth of 1.7 mm and a width of 16 mm. The element responsible for heating FC-72, which flowed laminarly in the minichannel, was a plate with an enhanced surface. Two types of surface textures were considered. Both were produced by vibration-assisted laser machining. Infrared thermography was used to record changes in the temperature on the outer smooth side of the plate. Two-phase flow patterns were observed through a glass pane. The main aim of the study was to analyze how the two types of surface textures affect the heat transfer coefficient. A two-dimensional heat transfer approach was proposed to determine the local values of the heat transfer coefficient. The inverse problem for the heated wall was solved using a semi-analytical method based on the Trefftz functions. The results are presented as relationships between the heat transfer coefficient and the distance along the minichannel length and as boiling curves. The experimental data obtained for the two types of enhanced heated surfaces was compared with the results recorded for the smooth heated surface. The highest local values of the heat transfer coefficient were reported in the saturated boiling region for the plate with the type 1 texture produced by vibration-assisted laser machining.

  18. Heat-Flux Measurements in Laser-Produced Plasmas Using Thomson Scattering from Electron Plasma Waves

    Science.gov (United States)

    Henchen, R. J.; Goncharov, V. N.; Cao, D.; Katz, J.; Froula, D. H.; Rozmus, W.

    2017-10-01

    An experiment was designed to measure heat flux in coronal plasmas using collective Thomson scattering. Adjustments to the electron distribution function resulting from heat flux affect the shape of the collective Thomson scattering features through wave-particle resonance. The amplitude of the Spitzer-Härm electron distribution function correction term (f1) was varied to match the data and determines the value of the heat flux. Independent measurements of temperature and density obtained from Thomson scattering were used to infer the classical heat flux (q = - κ∇Te) . Time-resolved Thomson-scattering data were obtained at five locations in the corona along the target normal in a blowoff plasma formed from a planar Al target with 1.5 kJ of 351-nm laser light in a 2-ns square pulse. The flux measured through the Thomson-scattering spectra is a factor of 5 less than the κ∇Te measurements. The lack of collisions of heat-carrying electrons suggests a nonlocal model is needed to accurately describe the heat flux. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  19. 4-nm continuous rapid sweeping spectroscopy in 2-μm band using distributed Bragg reflector laser

    Science.gov (United States)

    Abe, M.; Kanai, T.; Fujiwara, N.; Ohiso, Y.; Ishii, H.; Shimokozono, M.; Mastuzaki, H.; Kasahara, R.; Itoh, M.

    2017-10-01

    We apply a newly developed 2-μm distributed Bragg reflector (DBR) laser to CO2 spectroscopy. We achieve mode-hop free wavelength tuning over 4 nm by sweeping the DBR current and phase control current, simultaneously. The sensitivity of this laser spectroscopy system is better than 5 × 10-3, which is the noise level, and means that a CO2 concentration of 400 ppm can be detected with a path length of 1 m. We confirm that the DBR laser in the 2-μm region maintains a wide tunability of 4 nm even when rapidly swept at a scan rate of 10 kHz.

  20. Bulk Combinatorial Synthesis and High Throughput Characterization for Rapid Assessment of Magnetic Materials: Application of Laser Engineered Net Shaping (LENS™)

    Science.gov (United States)

    Geng, J.; Nlebedim, I. C.; Besser, M. F.; Simsek, E.; Ott, R. T.

    2016-07-01

    A bulk combinatorial approach for synthesizing alloy libraries using laser engineered net shaping (LENS™; i.e., 3D printing) was utilized to rapidly assess material systems for magnetic applications. The LENS™ system feeds powders in different ratios into a melt pool created by a laser to synthesize samples with bulk (millimeters) dimensions. By analyzing these libraries with autosampler differential scanning calorimeter/thermal gravimetric analysis and vibrating sample magnetometry, we are able to rapidly characterize the thermodynamic and magnetic properties of the libraries. The Fe-Co binary alloy was used as a model system and the results were compared with data in the literature.

  1. Rapid infrared laser sealing and cutting of porcine renal vessels, ex vivo

    Science.gov (United States)

    Giglio, Nicholas C.; Hutchens, Thomas C.; Perkins, William C.; Latimer, Cassandra; Ward, Arlen; Nau, William H.; Fried, Nathaniel M.

    2014-03-01

    Suture ligation with subsequent cutting of blood vessels to maintain hemostasis during surgery is time consuming and skill intensive. Energy-based, electrosurgical and ultrasonic devices are often used to replace sutures and mechanical clips to provide rapid hemostasis, and decrease surgical time. Some of these devices may create undesirably large collateral zones of thermal damage and tissue necrosis, or require separate mechanical blades for cutting. Infrared lasers are currently being explored as alternative energy sources for vessel sealing applications. In a previous study, a 1470-nm laser was used to seal vessels of 1-6 mm in diameter in 5 s, yielding burst pressures of ~ 500 mmHg. The purpose of this study was to provide faster sealing, incorporate transection of the sealed vessels, and increase the burst pressure. A 110-Watt, 1470-nm laser beam was transmitted through a fiber and beam shaping optics, producing a linear beam 3.0 mm by 9.5 mm for sealing, and 1.1 mm by 9.6 mm for cutting (FWHM). A twostep process sealed then transected ex vivo porcine renal vessels (1-8.5 mm diameter) in a bench top setup. Seal and cut times were 1.0 s each. A standard burst pressure system measured resulting seal strength, and gross and histologic thermal damage measurements were also recorded. All blood vessels tested (n = 30) were sealed and cut, with total irradiation times of 2.0 s, mean burst pressures > 1000 mmHg (compared to normal systolic blood pressure of 120 mmHg), and combined seal/collateral thermal coagulation zones of 2-3 mm. The results of this study demonstrated that an optical-based system is capable of precisely sealing and cutting a wide range of porcine renal vessel sizes, and with further development, may provide an alternative to radiofrequency and ultrasound-based vessel sealing devices.

  2. Direct measurement of the instantaneous linewidth of rapidly wavelength-swept lasers.

    Science.gov (United States)

    Biedermann, Benjamin R; Wieser, Wolfgang; Eigenwillig, Christoph M; Klein, Thomas; Huber, Robert

    2010-11-15

    The instantaneous linewidth of rapidly wavelength-swept laser sources as used for optical coherence tomography (OCT) is of crucial interest for a deeper understanding of physical effects involved in their operation. Swept lasers for OCT, typically sweeping over ~15 THz in ~10 μs, have linewidths of several gigahertz. The high optical-frequency sweep speed makes it impossible to measure the instantaneous spectrum with standard methods. Hence, up to now, experimental access to the instantaneous linewidth was rather indirect by the inverse Fourier transform of the coherence decay. In this Letter, we present a method by fast synchronous time gating and extraction of a "snapshot" of the instantaneous spectrum with an electro-optic modulator, which can subsequently be measured with an optical spectrum analyzer. This new method is analyzed in detail, and systematic artifacts, such as sideband generation due to the modulation and residual wavelength uncertainty due to the sweeping operation, are quantified. The method is checked for consistency with results from the common, more indirect measurement via coherence properties.

  3. Rapid prototyping of flexible intrafascicular electrode arrays by picosecond laser structuring

    Science.gov (United States)

    Mueller, Matthias; de la Oliva, Natalia; del Valle, Jaume; Delgado-Martínez, Ignacio; Navarro, Xavier; Stieglitz, Thomas

    2017-12-01

    Objective. Interfacing the peripheral nervous system can be performed with a large variety of electrode arrays. However, stimulating and recording a nerve while having a reasonable amount of channels limits the number of available systems. Translational research towards human clinical trial requires device safety and biocompatibility but would benefit from design flexibility in the development process to individualize probes. Approach. We selected established medical grade implant materials like precious metals and Parylene C to develop a rapid prototyping process for novel intrafascicular electrode arrays using a picosecond laser structuring. A design for a rodent animal model was developed in conjunction with an intrafascicular implantation strategy. Electrode characterization and optimization was performed first in saline solution in vitro before performance and biocompatibility were validated in sciatic nerves of rats in chronic implantation. Main results. The novel fabrication process proved to be suitable for prototyping and building intrafascicular electrode arrays. Electrochemical properties of the electrode sites were enhanced and tested for long-term stability. Chronic implantation in the sciatic nerve of rats showed good biocompatibility, selectivity and stable stimulation thresholds. Significance. Established medical grade materials can be used for intrafascicular nerve electrode arrays when laser structuring defines structure size in the micro-scale. Design flexibility reduces re-design cycle time and material certificates are beneficial support for safety studies on the way to clinical trials.

  4. Fabrication and characterization of selective laser melting printed Ti–6Al–4V alloys subjected to heat treatment for customized implants design

    Directory of Open Access Journals (Sweden)

    Mengke Wang

    2016-12-01

    Full Text Available Selective laser melting (SLM is a promising technique capable of rapidly fabricating customized implants having desired macro- and micro-structures by using computer-aided design models. However, the SLM-based products often have non-equilibrium microstructures and partial surface defects because of the steep thermal gradients and high solidification rates that occur during the laser melting. To meet clinical requirements, a heat treatment was used to tailor the physiochemical properties, homogenize the metallic microstructures, and eliminate surface defects, expecting to improve the cytocompatibility in vitro. Compared with the as-printed Ti–6Al–4V substrate, the heat-treated substrate had a more hydrophilic, rougher and more homogeneous surface, which should promote the early cell attachment, proliferation and osseointegration. More importantly, a crystalline rutile TiO2 layer formed during the heat treatment, which should greatly promote the biocompatibility and corrosion resistance of the implant. Compared to the untreated surfaces, the adhesion and proliferation of human bone mesenchymal stem cells (hBMSCs on heat-treated substrates were significantly enhanced, implying an excellent cytocompatibility after annealing. Therefore, these findings provide an alternative to biofunctionalized SLM-based Ti–6Al–4V implants with optimized physiochemical properties and biocompatibility for orthopedic and dental applications.

  5. Analytical model for the extent of the heat-affected zone occurring during overlap laser welding of dissimilar materials

    Science.gov (United States)

    Jarwitz, M.; Weber, R.; Graf, T.

    2017-10-01

    An analytical model to predict the extent of the heat-affected zone in laser-welded dissimilar materials with strongly differing thermal properties is presented. The model applies to the joining of two materials, where the heat-affected zone occurs in the joining partner with low thermal responsivity. Heat is supplied to the joining partner with high thermal responsivity and heat conduction is the only mechanism of heat transfer. The model is applied to the laser welding of solid nickel sheets to sheets of nickel foam. With a deviation of less than 1.5%, the extent of the heat-affected zone predicted by the model is in excellent agreement with the ones determined experimentally.

  6. Vibration-Assisted Laser Surface Texturing and Electromachining for the Intensification of Boiling Heat Transfer in a Minichannel

    Directory of Open Access Journals (Sweden)

    Piasecka M.

    2017-12-01

    Full Text Available The paper describes applications of the vibration-assisted laser surface texturing and spark erosion process as methods of modifying properties and structures of metal surfaces. Practical aspects of the use of produced surfaces in the heat exchanger with a minichannel have been described. Compared with smooth surfaces, developed metal surfaces obtained by vibration-assisted laser surface texturing and electromachining show more effective heat transfer. The local heat transfer coefficient for the saturated boiling region obtained for developed surfaces had the values significantly higher than those obtained for the smooth plate at the same heat flux. The experimental results are presented as the heated plate temperature (obtained from infrared thermography and relationships between the heat transfer coefficient and the distance along the length of the minichannel for the saturated boiling region.

  7. High Heat Flux Interactions and Tritium Removal from Plasma Facing Components by a Scanning Laser

    Energy Technology Data Exchange (ETDEWEB)

    C.H. Skinner; C.A. Gentile; A. Hassanein

    2002-01-28

    A new technique for studying high heat flux interactions with plasma facing components is presented. The beam from a continuous wave 300 W neodymium laser was focused to 80 W/mm2 and scanned at high speed over the surface of carbon tiles. These tiles were previously used in the TFTR [Tokamak Fusion Test Reactor] inner limiter and have a surface layer of amorphous hydrogenated carbon that was codeposited during plasma operations. Laser scanning released up to 84% of the codeposited tritium. The temperature rise of the codeposit on the tiles was significantly higher than that of the manufactured material. In one experiment, the codeposit surface temperature rose to 1,770 C while for the same conditions, the manufactured surface increased to only 1,080 C. The peak temperature did not follow the usual square-root dependence on heat pulse duration. Durations of order 100 ms resulted in brittle destruction and material loss from the surface, while a duration of approximately 10 ms showed minimal change. A digital microscope imaged the codeposit before, during, and after the interaction with the laser and revealed hot spots on a 100-micron scale. These results will be compared to analytic modeling and are relevant to the response of plasma facing components to disruptions and vertical displacement events (VDEs) in next-step magnetic fusion devices.

  8. Experimental evidence for short-pulse laser heating of solid-density target to high bulk temperatures.

    Science.gov (United States)

    Soloviev, A; Burdonov, K; Chen, S N; Eremeev, A; Korzhimanov, A; Pokrovskiy, G V; Pikuz, T A; Revet, G; Sladkov, A; Ginzburg, V; Khazanov, E; Kuzmin, A; Osmanov, R; Shaikin, I; Shaykin, A; Yakovlev, I; Pikuz, S; Starodubtsev, M; Fuchs, J

    2017-09-22

    Heating efficiently solid-density, or even compressed, matter has been a long-sought goal in order to allow investigation of the properties of such state of matter of interest for various domains, e.g. astrophysics. High-power lasers, pinches, and more recently Free-Electron-Lasers (FELs) have been used in this respect. Here we show that by using the high-power, high-contrast "PEARL" laser (Institute of Applied Physics-Russian Academy of Science, Nizhny Novgorod, Russia) delivering 7.5 J in a 60 fs laser pulse, such coupling can be efficiently obtained, resulting in heating of a slab of solid-density Al of 0.8 µm thickness at a temperature of 300 eV, and with minimal density gradients. The characterization of the target heating is achieved combining X-ray spectrometry and measurement of the protons accelerated from the Al slab. The measured heating conditions are consistent with a three-temperatures model that simulates resistive and collisional heating of the bulk induced by the hot electrons. Such effective laser energy deposition is achieved owing to the intrinsic high contrast of the laser which results from the Optical Parametric Chirped Pulse Amplification technology it is based on, allowing to attain high target temperatures in a very compact manner, e.g. in comparison with large-scale FEL facilities.

  9. Changes in dental enamel oven heated or irradiated with Er,Cr:YSGG laser. Analysis by FTIR

    Science.gov (United States)

    Rabelo, J. S.; Ana, P. A.; Benetti, C.; Valério, M. E. G.; Zezell, D. M.

    2010-04-01

    This study evaluated the change that occurs in dental enamel under action of oven heating or Er,Cr:YSGG laser irradiation aiming to obtain a structure more resistant to demineralization. Enamel powder was obtained from bovine teeth. Samples were subjected to oven heating at temperatures of 200, 400, 600, 800, and 1000°C or during laser irradiation with energy densities of 7.53, 10.95, and 13.74 J/cm2. The infrared thermography was used to measure the surface temperature generated in the solid samples of enamel during lasers irradiation. The samples were analyzed by Fourier transform infrared spectroscopy (FTIR), which shows changes on enamel oven heated or laser irradiated, due to treatments, related to carbonates, adsorbed water and hydroxyl content. These compositional effects were more evident in lased samples. These changes may alter the material properties such as its solubility, and decrese of demineralization that is important for caries prevention.

  10. Monitoring and rapid quantification of total carotenoids in Rhodotorula glutinis cells using laser tweezers Raman spectroscopy.

    Science.gov (United States)

    Tao, Zhanhua; Wang, Guiwen; Xu, Xiaodong; Yuan, Yufeng; Wang, Xue; Li, Yongqing

    2011-01-01

    Rhodotorula glutinis is known to accumulate large amounts of carotenoids under certain culture conditions, which have very important industrial applications. So far, the molecular mechanism of regulating carotenogenesis is still not well understood. To better understand the carotenogenesis process, it requires methods that can detect carotenogenesis rapidly and reliably in single live cells. In this paper, a method based on laser tweezers Raman spectroscopy (LTRS) was developed to directly detect carotenoids, as well as other important biological molecules in single live R. glutinis cells. The data showed that the accumulation of carotenoids and lipids occurred mainly in the late exponential and stationary phases when the cell growth was inhibited by nutrient limitation. Meanwhile, the carotenoid concentration changed together with the concentration of nucleic acids, which increased in the first phase and decreased in the last phase of the culture. These data demonstrate that LTRS is a rapid, convenient, and reliable method to study the carotenogenesis process in vivo. © 2010 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  11. Replication of human tracheobronchial hollow airway models using a selective laser sintering rapid prototyping technique.

    Science.gov (United States)

    Clinkenbeard, Rodney E; Johnson, David L; Parthasarathy, Ramkumar; Altan, M Cengiz; Tan, Kah-Hoe; Park, Seok-Min; Crawford, Richard H

    2002-01-01

    Exposures to toxic or pathogenic aerosols are known to produce adverse health effects. The nature and severity of these effects often are governed in large part by the location and amount of aerosol deposition within the respiratory tract. Morphologically detailed replica hollow lung airway casts are widely used in aerosol deposition research; however, techniques are not currently available that allow replicate deposition studies in identical morphologically detailed casts produced from a common reference anatomy. This project developed a technique for the precision manufacture of morphologically detailed human tracheobronchial airway models based on high-resolution anatomical imaging data. Detailed physical models were produced using the selective laser sintering (SLS) rapid prototyping process. Input to the SLS process was a three-dimensional computer model developed by boundary-based two-dimension to three-dimension conversion of anatomical images from the original National Institutes of Health/National Library of Medicine Visible Human male data set. The SLS process produced identical replicate models that corresponded exactly to the anatomical section images, within the limits of the measurement. At least five airway generations were achievable, corresponding to airways less than 2 mm in diameter. It is anticipated that rapid prototyping manufacture of respiratory tract structures based on reference anatomies such as the Visible Male and Visible Female may provide "gold standard" models for inhaled aerosol deposition studies. Adaptations of the models to represent various disease states may be readily achieved, thereby promoting exploration of pharmaceutical research on targeted drug delivery via inhaled aerosols.

  12. Rapid contrasting of ultrathin sections using microwave irradiation with heat dissipation.

    Science.gov (United States)

    Hernández-Chavarría, F; Vargas-Montero, M

    2001-08-01

    The use of microwave irradiation (MWI) to accelerate fixation, dehydration and contrasting (staining) for electron microscopy has been applied to the development of rapid methods to process biological samples in electron microscopy. A simple explanation is that the reduced time in those procedures is due to heating. In this paper we propose a contrasting method for thin sections that avoids the thermal effects of MWI. Grids with thin sections of mouse kidney, the dinoflagellate Alexandrium monilatum, spermatophores of the fly Archicepsis diversiformis, the bacteria Acinetobacter calcoaceticum and Enterobacter cloacae were placed into Beem capsules and stained with uranyl acetate and lead citrate, while immersed in an ice-water bath, and irradiated for periods ranging from 30 s to 2 min. After each contrasting procedure, the Beem capsule was filled with distilled water to wash the grids under MWI with the same irradiation time as used to contrast. Good results were obtained on irradiating for 1 min and the temperature of the Beem capsule was maintained around 5 degrees C.

  13. Use of a laser-induced fluorescence thermal imaging system for film cooling heat transfer measurement

    Energy Technology Data Exchange (ETDEWEB)

    Chyu, M.K. [Carnegie Mellon Univ., Pittsburgh, PA (United States)

    1995-10-01

    This paper describes a novel approach based on fluorescence imaging of thermographic phosphor that enables the simultaneous determination of both local film effectiveness and local heat transfer on a film-cooled surface. The film cooling model demonstrated consists of a single row of three discrete holes on a flat plate. The transient temperature measurement relies on the temperature-sensitive fluorescent properties of europium-doped lanthanum oxysulfide (La{sub 2}O{sub 2}S:EU{sup 3+}) thermographic phosphor. A series of full-field surface temperatures, mainstream temperatures, and coolant film temperatures were acquired during the heating of a test surface. These temperatures are used to calculate the heat transfer coefficients and the film effectiveness simultaneously. Because of the superior spatial resolution capability for the heat transfer data reduced from these temperature frames, the laser-induced fluorescence (LIF) imaging system, the present study observes the detailed heat transfer characteristics over a film-protected surface. The trend of the results agrees with those obtained using other conventional thermal methods, as well as the liquid crystal imaging technique. One major advantage of this technique is the capability to record a large number of temperature frames over a given testing period. This offers multiple-sample consistency.

  14. Rapid Detection of Pediatric Bacteriuria Using Narrow Angle Forward Laser Scattering Technology (NAFLST) with Bacterioscan

    Science.gov (United States)

    Cline, Adriana; Jhaveri, Ravi; Levinson, Kara; Miller, Melissa

    2017-01-01

    Abstract Background Pediatric urinary tract infections (UTI) are common, but culture-based diagnosis can take up to 48 hours. This time delay means patients are exposed to potentially unnecessary antibiotics. The sensitivity of screening urinalysis can vary, so rapid detection of UTI by another means would be beneficial. Narrow Angle Forward Laser Scattering Technology (NAFLST) with Bacterioscan can rapidly detect bacteriuria by shining a laser continuously through a liquid sample containing replicating bacteria, and graphing the degree of light refraction over time. Higher degrees of light refraction represent higher initial bacterial load and continued bacterial growth. After 3 hours, the optical scatter classifies a sample as either Likely Positive or Likely Negative. We compared Bacterioscan results to culture data in pediatric patients to assess the ability to diagnose UTI and avoid unnecessary urine culture. Methods This protocol was approved by the UNC Biomedical Institutional Review Board. Over one month, 169 pediatric (<18 yo) urine cultures were collected as part of routine patient care. An individual urine sample and 2.5mL of Sterile Tryptic Soy Broth were pipetted into a Bacterioscan micro-curette. Bacterioscan labeled the specimen as Likely Positive or Likely Negative after a 3 hour period. Results were then compared with urine culture results obtained by routine microbiologic methods. Results Of the 169 urine cultures, 96 were positive, but only 27 were positive for uropathogens. Bacterioscan was 100% sensitive and 58.4% specific in predicting clinically relevant/pathogenic bacterial growth in culture (PPV 31.3%, NPV 100%), and 70.8% sensitive and 75.3% specific in predicting any bacterial growth (PPV 79.0%, NPV 66.2%). If a “Likely Positive” Bacterioscan result had been used in our study population to screen urine samples for culture, then 58% (83/142) of negative urine cultures would have been eliminated with no UTIs missed. Conclusion By

  15. Pulsed laser Raman spectroscopy in the laser-heated diamond anvil cell

    Energy Technology Data Exchange (ETDEWEB)

    Goncharov, A F; Crowhurst, J C

    2005-03-24

    We describe the design and operation of a spatially-filtered Raman/fluorescence spectrometer that incorporates a pulsed 532 nm laser excitation source and a synchronized and electronically gated CCD detector. This system permits the suppression of undesired continuous radiation from various sources by a factor of up to 50,000 providing the possibility of acquiring Raman signals at temperatures exceeding 5,000 K. We present performance comparisons of this system with that of a state-of-the-art conventional CW system using a 458 nm excitation source. We also demonstrate that the pulsed system is capable of suppressing an impurity-induced (single nitrogen defects) fluorescence in diamond, and further suggest that this capability can be used to suppress the stress-induced fluorescence in diamond that may appear at pressures near or above 150 GPa.

  16. Manufacturing of a high-temperature resistojet heat exchanger by selective laser melting

    Science.gov (United States)

    Romei, F.; Grubišić, A. N.; Gibbon, D.

    2017-09-01

    The paper presents the design, manufacturing and postproduction analysis of a novel high-temperature spacecraft resistojet heat exchanger manufactured through selective laser melting to validate the manufacturing approach. The work includes the analysis of critical features of a heat exchanger with integrated converging-diverging nozzle as a single piece element. The metrology of the component is investigated using optical analysis and profilometry to verify the integrity of components. High-resolution micro-Computed Tomography (CT) is applied as a tool for volumetric non-destructive inspection and conformity since the complex geometry of the thruster does not allow internal examination. The CT volume data is utilised to determine a surface mesh on which a novel perform coordinate measurement technique is applied for nominal/actual comparison and wall thickness analysis. A thin-wall concentric tubular heat exchanger design is determined to meet dimensional accuracy requirements. The work indicates the production of fine structures with feature sizes below 200 μm in 316L stainless via selective laser melting is feasible and opens up new possibilities for the future developments in multiple industries.

  17. Comprehensive analysis of heat generation and efficient measurement of fractional thermal loading in a solid-state laser medium

    Science.gov (United States)

    Wang, Y. T.; Zhang, R. H.

    2017-12-01

    In this paper we provide a detailed analysis of heat generation in a solid-state laser medium. The fractional thermal loadings are different for different physical processes in a laser medium, including the fluorescence process, stimulated emission, energy transfer up-conversion and excited-state absorption. Applying this theoretical analysis in a diode-end-pumped Nd:GdVO4 laser at 1342 nm, and using a simple and efficient method to measure the thermal loading of the solid-state laser medium presented, the experimental results are in good agreement with the theoretically calculated results.

  18. Burst train generator of high energy femtosecond laser pulses for driving heat accumulation effect during micromachining.

    Science.gov (United States)

    Rezaei, Saeid; Li, Jianzhao; Herman, Peter R

    2015-05-01

    A new method for generating high-repetition-rate (12.7-38.2 MHz) burst trains of femtosecond laser pulses has been demonstrated for the purpose of tailoring ultrashort laser interactions in material processing that can harness the heat accumulation effect among pulses separated by a short interval (i.e., 26 ns). Computer-controlled time delays were applied to synchronously trigger the high frequency switching of a high voltage Pockels cell to specify distinctive values of polarization rotation for each round-trip of a laser pulse cycling within a passive resonator. Polarization dependent output coupling facilitated the flexible shaping of the burst envelope profile to provide burst trains of up to ∼1  mJ of burst energy divided over a selectable number (1 to 25) of pulses. Individual pulses of variable energy up to 150 μJ and with pulse duration tunable over 70 fs to 2 ps, were applied in burst trains to generate deep and high aspect ratio holes that could not form with low-repetition-rate laser pulses.

  19. Prediction of laser cutting heat affected zone by extreme learning machine

    Science.gov (United States)

    Anicic, Obrad; Jović, Srđan; Skrijelj, Hivzo; Nedić, Bogdan

    2017-01-01

    Heat affected zone (HAZ) of the laser cutting process may be developed based on combination of different factors. In this investigation the HAZ forecasting, based on the different laser cutting parameters, was analyzed. The main goal was to predict the HAZ according to three inputs. The purpose of this research was to develop and apply the Extreme Learning Machine (ELM) to predict the HAZ. The ELM results were compared with genetic programming (GP) and artificial neural network (ANN). The reliability of the computational models were accessed based on simulation results and by using several statistical indicators. Based upon simulation results, it was demonstrated that ELM can be utilized effectively in applications of HAZ forecasting.

  20. Laser heated boron doped diamond electrodes: effect of temperature on outer sphere electron transfer processes.

    Science.gov (United States)

    Meng, Lingcong; Iacobini, James G; Joseph, Maxim B; Macpherson, Julie V; Newton, Mark E

    2014-01-01

    Thermoelectrochemical experiments can reveal significant information about electrochemical processes compared to ambient only measurements. Typical thermoelectrochemistry is performed using resistively heated wires or laser heated electrodes, both of which can suffer drawbacks associated with the electrode material employed. Boron doped diamond (BDD) is ideal for thermoelectrochemical investigations due to its extremely high thermal conductivity and diffusivity, extreme resistance to thermal ablation (can withstand laser power densities, Pd, of GW cm(-2) for nanosecond pulses) and excellent electrochemical properties (low background currents and wide potential window). In this paper we describe the use of a pulsed laser technique to heat the rear of a 1 mm diameter conducting BDD disc electrode, which drives electrochemical solution reactions at the front face. Maximum electrode temperatures of 90.0 °C were recorded experimentally and confirmed by finite element modelling (FEM). The effect of laser pulsed heating (maximum 3.8 kW cm(-2); 10 ms on and 90 ms off) on the cyclic voltammetric response of two fast (reversible) outer sphere electron transfer redox mediators (Ru(NH3)6(3+/2+) and IrCl6(2-/3-)) are investigated. In particular, we observe pulsed increases in the current, which increase with increasing Pd. The potential of the peak current is shifted positively for the Ru(NH3)6(3+/2+) couple (in accordance with a positive temperature coefficient, β, +0.68 mV K(-1)) and negatively for the IrCl6(3-/2-) couple (β = -0.48 mV K(-1)). Scanning backwards, in contrast to that observed for a macrodisc electrode in ambient solution, a cathodic peak is again observed for Ru(NH3)6(3+/2+) and an anodic peak for IrCl6(3-/2-) couple. We attribute this response to the entropy of the redox reaction and the time-dependant change in mass transport due to the induced thermal gradients at the electrode/electrolyte interface. The observed responses are in qualitative agreement

  1. A free-electron laser for cyclotron resonant heating in magnetic fusion reactors

    Science.gov (United States)

    Freund, H. P.; Read, M. E.; Jackson, R. H.; Pershing, D. E.; Taccetti, J. M.

    1995-05-01

    A G-band free-electron laser designed for plasma heating is described using a coaxial hybrid iron (CHI) wiggler formed by insertion into a solenoid of a central rod and an outer ring of alternating ferrite and nonferrite spacers positioned so that the central ferrite (nonferrite) spacers are opposite the outer nonferrite (ferrite) spacers. The CHI wiggler provides for enhanced beam focusing and the ability to handle intense beams and high-power continuous wave radiation. Simulations indicate that a power/efficiency of 3.5 MW/13% are possible using a 690 kV/40 A beam. No beam loss was found in simulation.

  2. Laser thinning for monolayer graphene formation: heat sink and interference effect.

    Science.gov (United States)

    Han, Gang Hee; Chae, Seung Jin; Kim, Eun Sung; Güneş, Fethullah; Lee, Il Ha; Lee, Sang Won; Lee, Si Young; Lim, Seong Chu; Jeong, Hae Kyung; Jeong, Mun Seok; Lee, Young Hee

    2011-01-25

    Despite the availability of large-area graphene synthesized by chemical vapor deposition (CVD), the control of a uniform monolayer graphene remained challenging. Here, we report a method of acquiring monolayer graphene by laser irradiation. The accumulation of heat on graphene by absorbing light, followed by oxidative burning of upper graphene layers, which strongly relies on the wavelength of light and optical parameters of the substrate, was in situ measured by the G-band shift in Raman spectroscopy. The substrate plays a crucial role as a heat sink for the bottom monolayer graphene, resulting in no burning or etching. Oscillatory thinning behavior dependent on the substrate oxide thickness was evaluated by adopting a simple Fresnel's equation. This paves the way for future research in utilizing monolayer graphene for high-speed electronic devices.

  3. Jet-type, water-cooled heat sink that yields 255-W continuous-wave laser output at 808 nm from a 1-cm laser diode bar.

    Science.gov (United States)

    Miyajima, Hirofumi; Kan, Hirofumi; Kanzaki, Takeshi; Furuta, Shin-ichi; Yamanaka, Masanobu; Izawa, Yasukazu; Nakai, Sadao

    2004-02-01

    A newly designed jet-type, water-cooled heat sink (the funryu heat sink, meaning fountain flow in Japanese) yielded 255-W cw laser output at 808 nm from a 1-cm bar made from InGaAsP/InGaP quantum-well active layers with a 67% fill factor [70 quantum-well laser diode (LD) array along the 1-cm bar]. A funryu heat sink measuring 1.1 mm in thickness gave the LD 0.25 degrees C/W thermal resistance, one of the lowest values achieved with a 1-cm LD bar. Over a short period of operation, the device reached a maximum cw power of 255 W. To the best of our knowledge, this is the highest power ever achieved in 808-nm LD operation. In the future, the funryu heat sink may be capable of 80-W cw operation over an extended lifetime of several thousand hours.

  4. High-speed scanning ablation of dental hard tissues with a λ=9.3-μm CO2 laser: heat accumulation and peripheral thermal damage

    Science.gov (United States)

    Nguyen, Daniel; Staninec, Michal; Lee, Chulsung; Fried, Daniel

    2010-02-01

    A mechanically scanned CO2 laser operated at high laser pulse repetition rates can be used to rapidly and precisely remove dental decay. This study aims to determine whether these laser systems can safely ablate enamel and dentin without excessive heat accumulation and peripheral thermal damage. Peripheral thermal damage can adversely impact the mechanical strength of the irradiated tissue, particularly for dentin, and reduce the adhesion characteristics of the modified surfaces. Samples were derived from noncarious extracted molars. Pulpal temperatures were recorded using microthermocouples situated at the pulp chamber roof of samples (n=12), which were occlusally ablated using a rapid-scanning, water-cooled 300 Hz CO2 laser over a two minute time course. The mechanical strength of facially ablated dentin (n=10) was determined via four-point bend test and compared to control samples (n=10) prepared with 320 grit wet sand paper to simulate conventional preparations. Composite-to-enamel bond strength was measured via single-plane shear test for ablated/non-etched (n=10) and ablated/acid-etched (n=8) samples and compared to control samples (n=9) prepared by 320 grit wet sanding. Thermocouple measurements indicated that the temperature remained below ambient temperature at 19.0°C (s.d.=0.9) if water-cooling was used. There was no discoloration of either dentin and enamel, the treated surfaces were uniformly ablated and there were no cracks observable on the laser treated surfaces. Fourpoint bend tests yielded mean mechanical strengths of 18.2 N (s.d.=4.6) for ablated dentin and 18.1 N (s.d.=2.7) for control (p>0.05). Shear tests yielded mean bond strengths of 31.2 MPa (s.d.=2.5, p<0.01) for ablated/acid-etched samples, 5.2 MPa (s.d.=2.4, p<0.001) for ablated/non-etched samples, and 37.0 MPa (s.d.=3.6) for control. The results indicate that a rapid-scanning 300 Hz CO2 laser can effectively ablate dentin and enamel without excessive heat accumulation and with minimal

  5. Rapid detection of undesired cosmetic ingredients by matrix-assisted laser desorption ionization time-of-flight mass spectrometry.

    Science.gov (United States)

    Ouyang, Jie; An, Dongli; Chen, Tengteng; Lin, Zhiwei

    2017-10-01

    In recent years, cosmetic industry profits soared due to the widespread use of cosmetics, which resulted in illicit manufacturers and products of poor quality. Therefore, the rapid and accurate detection of the composition of cosmetics has become crucial. At present, numerous methods, such as gas chromatography and liquid chromatography-mass spectrometry, were available for the analysis of cosmetic ingredients. However, these methods present several limitations, such as failure to perform comprehensive and rapid analysis of the samples. Compared with other techniques, matrix-assisted laser desorption ionization time-of-flight mass spectrometry offered the advantages of wide detection range, fast speed and high accuracy. In this article, we briefly summarized how to select a suitable matrix and adjust the appropriate laser energy. We also discussed the rapid identification of undesired ingredients, focusing on antibiotics and hormones in cosmetics.

  6. Ultra-Rapid 2-D and 3-D Laser Microprinting of Proteins

    Science.gov (United States)

    Scott, Mark Andrew

    When viewed under the microscope, biological tissues reveal an exquisite microarchitecture. These complex patterns arise during development, as cells interact with a multitude of chemical and mechanical cues in the surrounding extracellular matrix. Tissue engineers have sought for decades to repair or replace damaged tissue, often relying on porous scaffolds as an artificial extracellular matrix to support cell development. However, these grafts are unable to recapitulate the complexity of the in vivo environment, limiting our ability to regenerate functional tissue. Biomedical engineers have developed several methods for printing two- and three-dimensional patterns of proteins for studying and directing cell development. Of these methods, laser microprinting of proteins has shown the most promise for printing sub-cellular resolution gradients of cues, but the photochemistry remains too slow to enable large-scale applications for screening and therapeutics In this work, we demonstrate a novel high-speed photochemistry based on multi-photon photobleaching of fluorescein, and we build the fastest 2-D and 3-D laser microprinter for proteins to date. First, we show that multiphoton photobleaching of a deoxygenated solution of biotin-4-fluorescein onto a PEG monolayer with acrylate end-group can enable print speeds of almost 20 million pixels per second at 600 nanometer resolution. We discovered that the mechanism of fluorescein photobleaching evolves from a 2-photon to 3- and 4-photon regime at higher laser intensities, unlocking faster printing kinetics. Using this 2-D printing system, we develop a novel triangle-ratchet method for directing the polarization of single hippocampal neurons. This ability to determine which neurite becomes an axon, and which neuritis become dendrites is an essential step for developing defined in vitro neural networks. Next, we modify our multiphoton photobleaching system to print in three dimensions. For the first time, we demonstrate 3

  7. Strategies for in situ laser heating in the diamond anvil cell at an X-ray diffraction beamline.

    Science.gov (United States)

    Petitgirard, Sylvain; Salamat, Ashkan; Beck, Pierre; Weck, Gunnar; Bouvier, Pierre

    2014-01-01

    An overview of several innovations regarding in situ laser-heating techniques in the diamond anvil cell at the high-pressure beamline ID27 of the European Synchrotron Radiation Facility is presented. Pyrometry measurements have been adapted to allow simultaneous double-sided temperature measurements with the installation of two additional online laser systems: a CO2 and a pulsed Nd:YAG laser system. This reiteration of laser-heating advancements at ID27 is designed to pave the way for a new generation of state-of-the-art experiments that demand the need for synchrotron diffraction techniques. Experimental examples are provided for each major development. The capabilities of the double pyrometer have been tested with the Nd:YAG continuous-wave lasers but also in a time-resolved configuration using the nanosecond-pulsed Nd:YAG laser on a Fe sample up to 180 GPa and 2900 K. The combination of time-resolved X-ray diffraction with in situ CO2 laser heating is shown with the crystallization of a high-pressure phase of the naturally found pyrite mineral MnS2 (11 GPa, 1100-1650 K).

  8. Strategies for in situ laser heating in the diamond anvil cell at an X-ray diffraction beamline

    Science.gov (United States)

    Petitgirard, Sylvain; Salamat, Ashkan; Beck, Pierre; Weck, Gunnar; Bouvier, Pierre

    2014-01-01

    An overview of several innovations regarding in situ laser-heating techniques in the diamond anvil cell at the high-pressure beamline ID27 of the European Synchrotron Radiation Facility is presented. Pyrometry measurements have been adapted to allow simultaneous double-sided temperature measurements with the installation of two additional online laser systems: a CO2 and a pulsed Nd:YAG laser system. This reiteration of laser-heating advancements at ID27 is designed to pave the way for a new generation of state-of-the-art experiments that demand the need for synchrotron diffraction techniques. Experimental examples are provided for each major development. The capabilities of the double pyrometer have been tested with the Nd:YAG continuous-wave lasers but also in a time-resolved configuration using the nanosecond-pulsed Nd:YAG laser on a Fe sample up to 180 GPa and 2900 K. The combination of time-resolved X-ray diffraction with in situ CO2 laser heating is shown with the crystallization of a high-pressure phase of the naturally found pyrite mineral MnS2 (11 GPa, 1100–1650 K). PMID:24365921

  9. Effect of Laser Heat Treatment on Microstructures of 1Cr5Mo Steel Welded Joint

    Directory of Open Access Journals (Sweden)

    GUO Wei

    2017-01-01

    Full Text Available The surface of 1Cr5Mo heat-resistant steel welded joint was treated with CO2 laser,the microstructure and grain size grades of welded joints before and after laser heat treatment (LHT were analyzed with 4XC type optical microscope (OM,and the distribution of residual stress and retained austenite content in the surface of the welded joints were measured with X-ray diffraction (XRD stress tester.The results show that the grains of 1Cr5Mo steel welded joints are refined by LHT,and the microstructure uniformity improves significantly,the grain levels of welded zone,fusion zone,overheated zone and normalized zone increase from level 9,level 9.8,level 8 and level 10.7 to level 10,level 10.2,level 8.5 and level 11 respectively,the mechanical weak areas reduce from overheated zone,welded zone and fusion zone to the overheated zone.The tensile residual stress in the welded joint surface is eliminated by LHT and a layer of compressive residual stress with thickness of about 0.28mm is formed.The residual austenite content in the welded joint surface increases after LHT,of which the distribution is more uniform and conducive to the improvement of mechanical properties.

  10. Femtosecond laser absorption, heat propagation, and damage threshold analysis for Au coating on metallic substrates

    Science.gov (United States)

    Suslova, Anastassiya; Hassanein, Ahmed

    2017-11-01

    The role of metallic substrates as a heat sink for thin layer gold coatings in double-layered optical components exposed to the ultrashort pulsed laser was investigated with the focus on the impact of the gold layer thickness. A two dimensional FEMTO-2D computational code for solid metallic targets with two-layered assemblies has been developed. The model is then used to simulate targets response to fs laser pulses at near damage threshold fluence and to determine the target damage threshold depending on its structure and the substrate material. Considering temperature dependent optical properties of a gold allowed us to make quantitative estimation of the damage threshold unlike many other models. The simulations show decreasing heat sink effect of the substrate with increasing coating thickness until it becomes negligible for 200 nm gold layer. Preliminary results show that a maximum improvement of the damage threshold of about 10% compared to a pure gold target is predicted for 50 nm gold coatings on two substrate materials: copper and nickel.

  11. Rapid Analysis of Ash Composition Using Laser-Induced Breakdown Spectroscopy (LIBS)

    Energy Technology Data Exchange (ETDEWEB)

    Tyler L. Westover

    2013-01-01

    Inorganic compounds are known to be problematic in the thermochemical conversion of biomass to syngas and ultimately hydrocarbon fuels. The elements Si, K, Ca, Na, S, P, Cl, Mg, Fe, and Al are particularly problematic and are known to influence reaction pathways, contribute to fouling and corrosion, poison catalysts, and impact waste streams. Substantial quantities of inorganic species can be entrained in the bark of trees during harvest operations. Herbaceous feedstocks often have even greater quantities of inorganic constituents, which can account for as much as one-fifth of the total dry matter. Current methodologies to measure the concentrations of these elements, such as inductively coupled plasma-optical emission spectrometry/mass spectrometry (ICP-OES/MS) are expensive in time and reagents. This study demonstrates that a new methodology employing laser-induced breakdown spectroscopy (LIBS) can rapidly and accurately analyze the inorganic constituents in a wide range of biomass materials, including both woody and herbaceous examples. This technique requires little or no sample preparation, does not consume any reagents, and the analytical data is available immediately. In addition to comparing LIBS data with the results from ICP-OES methods, this work also includes discussions of sample preparation techniques, calibration curves for interpreting LIBS spectra, minimum detection limits, and the use of internal standards and standard reference materials.

  12. Laser-Induced Breakdown Spectroscopy for the Rapid Characterization of Lead-Free Gunshot Residues.

    Science.gov (United States)

    Fambro, Lashaundra A; Vandenbos, Deidre D; Rosenberg, Matthew B; Dockery, Christopher R

    2017-04-01

    This study investigated the use of laser-induced breakdown spectroscopy (LIBS) and scanning electron microscopy energy dispersive X-ray spectroscopy (SEM-EDX) as means of characterizing gunshot residue (GSR) originating from commercially available lead-free rounds. Data from two experiments are presented in this work. One experiment focused on identifying prominent analytical markers present in lead-free GSR by LIBS while the other applied SEM-EDX to determine the degree of evidence preservation after LIBS analysis. Samples of GSR were collected via tape-lift method from the hands of volunteer shooters and instrumental analyses were conducted in triplicate. As a result, the lead-free ammunition analyzed in this work generated GSRs comprising primarily Ba, Al, Si, and/or K. Trace amounts of Ti, Fe, and S were also apparent in some compositions. Through SEM-EDX analysis, a spheroidal geometry consistent with traditional lead-containing GSR was observed. Additionally, it was determined that evidence is preserved after LIBS analysis which supports the implementation of LIBS as a rapid preliminary screening method followed by confirmatory testing via SEM-EDX on the preserved evidence.

  13. Rapid prototyping: porous titanium alloy scaffolds produced by selective laser melting for bone tissue engineering.

    Science.gov (United States)

    Warnke, Patrick H; Douglas, Timothy; Wollny, Patrick; Sherry, Eugene; Steiner, Martin; Galonska, Sebastian; Becker, Stephan T; Springer, Ingo N; Wiltfang, Jörg; Sivananthan, Sureshan

    2009-06-01

    Selective laser melting (SLM), a method used in the nuclear, space, and racing industries, allows the creation of customized titanium alloy scaffolds with highly defined external shape and internal structure using rapid prototyping as supporting external structures within which bone tissue can grow. Human osteoblasts were cultured on SLM-produced Ti6Al4V mesh scaffolds to demonstrate biocompatibility using scanning electron microscopy (SEM), fluorescence microscopy after cell vitality staining, and common biocompatibility tests (lactate dihydrogenase (LDH), 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT), 5-bromo-2-deoxyuridine (BrdU), and water soluble tetrazolium (WST)). Cell occlusion of pores of different widths (0.45-1.2 mm) was evaluated. Scaffolds were tested for resistance to compressive force. SEM investigations showed osteoblasts with well-spread morphology and multiple contact points. Cell vitality staining and biocompatibility tests confirmed osteoblast vitality and proliferation on the scaffolds. Pore overgrowth increased during 6 weeks' culture at pore widths of 0.45 and 0.5 mm, and in the course of 3 weeks for pore widths of 0.55, 0.6, and 0.7 mm. No pore occlusion was observed on pores of width 0.9-1.2 mm. Porosity and maximum compressive load at failure increased and decreased with increasing pore width, respectively. In summary, the scaffolds are biocompatible, and pore width influences pore overgrowth, resistance to compressive force, and porosity.

  14. Rapid spontaneous Raman light sheet microscopy using cw-lasers and tunable filters.

    Science.gov (United States)

    Rocha-Mendoza, Israel; Licea-Rodriguez, Jacob; Marro, Mónica; Olarte, Omar E; Plata-Sanchez, Marcos; Loza-Alvarez, Pablo

    2015-09-01

    We perform rapid spontaneous Raman 2D imaging in light-sheet microscopy using continuous wave lasers and interferometric tunable filters. By angularly tuning the filter, the cut-on/off edge transitions are scanned along the excited Stokes wavelengths. This allows obtaining cumulative intensity profiles of the scanned vibrational bands, which are recorded on image stacks; resembling a spectral version of the knife-edge technique to measure intensity profiles. A further differentiation of the stack retrieves the Raman spectra at each pixel of the image which inherits the 3D resolution of the host light sheet system. We demonstrate this technique using solvent solutions and composites of polystyrene beads and lipid droplets immersed in agar and by imaging the C-H (2800-3100cm(-1)) region in a C. elegans worm. The image acquisition time results in 4 orders of magnitude faster than confocal point scanning Raman systems, allowing the possibility of performing fast spontaneous Raman·3D-imaging on biological samples.

  15. Rapid Prototyping of Polymeric Nanopillars by 3D Direct Laser Writing for Controlling Cell Behavior.

    Science.gov (United States)

    Buch-Månson, Nina; Spangenberg, Arnaud; Gomez, Laura Piedad Chia; Malval, Jean-Pierre; Soppera, Olivier; Martinez, Karen L

    2017-08-23

    Mammalian cells have been widely shown to respond to nano- and microtopography that mimics the extracellular matrix. Synthetic nano- and micron-sized structures are therefore of great interest in the field of tissue engineering, where polymers are particularly attractive due to excellent biocompatibility and versatile fabrication methods. Ordered arrays of polymeric pillars provide a controlled topographical environment to study and manipulate cells, but processing methods are typically either optimized for the nano- or microscale. Here, we demonstrate polymeric nanopillar (NP) fabrication using 3D direct laser writing (3D DLW), which offers a rapid prototyping across both size regimes. The NPs are interfaced with NIH3T3 cells and the effect of tuning geometrical parameters of the NP array is investigated. Cells are found to adhere on a wide range of geometries, but the interface depends on NP density and length. The Cell Interface with Nanostructure Arrays (CINA) model is successfully extended to predict the type of interface formed on different NP geometries, which is found to correlate with the efficiency of cell alignment along the NPs. The combination of the CINA model with the highly versatile 3D DLW fabrication thus holds the promise of improved design of polymeric NP arrays for controlling cell growth.

  16. Topically applied methotrexate is rapidly delivered into skin by fractional laser ablation

    DEFF Research Database (Denmark)

    Taudorf, Elisabeth Hjardem; Lerche, Catharina; Vissing, Anne-Cathrine

    2015-01-01

    /v%) was measured from 0.25 to 24 h through AFXL-processed and intact porcine skin in Franz Cells (n = 46). A 2,940 nm fractional Erbium Yttrium Aluminium Garnet laser generated mid-dermal microchannels at 2.4% density, and 256 mJ/microchannel. HPLC quantified MTX-concentrations in extracts from mid-dermal skin...... sections, donor and receiver compartments. Fluorescence microscopy of UVC-activated MTX-fluorescence and desorption electro-spray ionization mass spectrometry imaging (DESI-MSI) evaluated MTX biodistribution. Results: AFXL-processed skin facilitated rapid MTX delivery through cone-shaped microchannels...... of 690 µm ablation depth, lined by the 47 µm thermal coagulation zone (CZ). Quantitatively, MTX was detectable by HPLC in mid-dermis after 15 min, significantly exceeded deposition in intact skin after 1.5 h, and saturated skin after 7 h at a 10-fold increased MTX-deposition versus intact skin (3.08 vs 0...

  17. Modeling of the Radial Heat Flow and Cooling Processes in a Deep Ultraviolet Cu+ Ne-CuBr Laser

    Directory of Open Access Journals (Sweden)

    Iliycho Petkov Iliev

    2009-01-01

    Full Text Available An improved theoretical model of the gas temperature profile in the cross-section of an ultraviolet copper ion excited copper bromide laser is developed. The model is based on the solution of the one-dimensional heat conduction equation subject to special nonlinear boundary conditions, describing the heat interaction between the laser tube and its surroundings. It takes into account the nonuniform distribution of the volume power density along with the radius of the laser tube. The problem is reduced to the boundary value problem of the first kind. An explicit solution of this model is obtained. The model is applied for the evaluation of the gas temperature profiles of the laser in the conditions of free and forced air-cooling. Comparison with other simple models assumed constant volume power density is made. In particular, a simple expression for calculating the average gas temperature is found.

  18. Effect of Heat Input on Microstructure and Hardness Distribution of Laser Welded Si-Al TRIP-Type Steel

    Directory of Open Access Journals (Sweden)

    Adam Grajcar

    2014-01-01

    Full Text Available This study is concerned with issues related to laser welding of Si-Al type TRIP steels with Nb and Ti microadditions. The tests of laser welding of thermomechanically rolled sheet sections were carried out using keyhole welding and a solid-state laser. The tests carried out for various values of heat input were followed by macro- and microscopic metallographic investigations as well as by microhardness measurements of welded areas. A detailed microstructural analysis was carried out in the penetration area and in various areas of the heat affected zone (HAZ. Special attention was paid to the influence of cooling conditions on the stabilisation of retained austenite, the most characteristic structural component of TRIP steels. The tests made it possible to determine the maximum value of heat input preventing the excessive grain growth in HAZ and to identify the areas of the greatest hardness reaching 520 HV0.1.

  19. Analytical solution to laser short-pulse heating of microsized metal wire: volumetric and surface heat source considerations

    National Research Council Canada - National Science Library

    Yilbas, B.S; Al-Dweik, A.Y

    2012-01-01

    .... The volumetric heat source resembles absorption by irradiated field according to Lambert’s Beer law while a surface heat source represents short pulse heating through high intensity thermal contact at the surface...

  20. Structure and properties of the Mg alloys in as-cast state and after heat and laser treatment

    OpenAIRE

    L.A. Dobrzański; T. Tański; J. Domagała; M. Król; Sz. Malara; A. Klimpel

    2008-01-01

    Purpose: The goal of this paper is to present the structure and properties of the magnesium cast alloys in as-cast state and after a heat treatment. Moreover in purpose of this paper is to extend a complex evaluation of magnesium alloys after laser surface treatment and the new methodology to determine the thermal characteristics of magnesium alloy using the novel Universal Metallurgical Simulator and Analyzer Platform (UMSA).Design/methodology/approach: Laser treatment of magnesium allo...

  1. Thermal Management of Rapid Fire Gun Breeches: The Case for Heat Pipes

    Science.gov (United States)

    1992-07-01

    at a Depth of 1 Inch ........................................... 23 10. The Effect of the Presence of an Embedded Heat Pipe: Temperature vs. Tim e...desired, the lower the boiling point of the liquid chosen has to be. Exercising the gun barrel heat transfer algorithm of Polk (1980), the effect of the presence of an

  2. Evaporation kinetics of laser heated silica in reactive and inert gases based on near-equilibrium dynamics.

    Science.gov (United States)

    Elhadj, Selim; Matthews, Manyalibo J; Yang, Steven T; Cooke, Diane J

    2012-01-16

    Evaporation kinetics of fused silica were measured up to ≈3000K using CO(2) laser heating, while solid-gas phase chemistry of silica was assessed with hydrogen, air, and nitrogen. Enhanced evaporation in hydrogen was attributed to an additional reduction pathway, while oxidizing conditions pushed the reaction backwards. The observed mass transport limitations supported use of a near-equilibrium analysis for interpreting kinetic data. A semi-empirical model of the evaporation kinetics is derived that accounts for heating, gas chemistry and transport properties. The approach described should have application to materials laser processing, and in applications requiring knowledge of thermal decomposition chemistry under extreme temperatures.

  3. Discovery of Rapid and Reversible Water Insertion in Rare Earth Sulfates: A New Process for Thermochemical Heat Storage.

    Science.gov (United States)

    Hatada, Naoyuki; Shizume, Kunihiko; Uda, Tetsuya

    2017-07-01

    Thermal energy storage based on chemical reactions is a prospective technology for the reduction of fossil-fuel consumption by storing and using waste heat. For widespread application, a critical challenge is to identify appropriate reversible reactions that occur below 250 °C, where abundant low-grade waste heat and solar energy might be available. Here, it is shown that lanthanum sulfate monohydrate La 2 (SO 4 ) 3 ⋅H 2 O undergoes rapid and reversible dehydration/hydration reactions in the temperature range from 50 to 250 °C upon heating/cooling with remarkably small thermal hysteresis (dehydration/hydration behavior. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. The asymptotic equivalence of fixed heat flux and fixed temperature thermal boundary conditions for rapidly rotating convection

    CERN Document Server

    Calkins, Michael A; Julien, Keith; Nieves, David; Driggs, Derek; Marti, Philippe

    2015-01-01

    The influence of fixed temperature and fixed heat flux thermal boundary conditions on rapidly rotating convection in the plane layer geometry is investigated for the case of stress-free mechanical boundary conditions. It is shown that whereas the leading order system satisfies fixed temperature boundary conditions implicitly, a double boundary layer structure is necessary to satisfy the fixed heat flux thermal boundary conditions. The boundary layers consist of a classical Ekman layer adjacent to the solid boundaries that adjust viscous stresses to zero, and a layer in thermal wind balance just outside the Ekman layers adjusts the temperature such that the fixed heat flux thermal boundary conditions are satisfied. The influence of these boundary layers on the interior geostrophically balanced convection is shown to be asymptotically weak, however. Upon defining a simple rescaling of the thermal variables, the leading order reduced system of governing equations are therefore equivalent for both boundary condit...

  5. Effects of laser-induced heating on nitrogen-vacancy centers and single-nitrogen defects in diamond

    Science.gov (United States)

    Szczuka, Conrad; Drake, Melanie; Reimer, Jeffrey A.

    2017-10-01

    We investigate the effects of laser-induced heating of NV- and P1 defects in diamonds by X-band CW EPR spectroscopy, with particular attention to temperature effects on the zero field splitting and electron polarization. A 532 nm laser with intensities of 7-36 mW mm-2 is sufficient to heat diamond samples from room temperature to 313-372 K in our experimental setup. The temperature effects on the determined NV- zero-field splittings are consistent with previously observed non-optical heating experiments. Electron spin polarization of the NV- defects were observed to increase, then saturate, with increasing laser light intensities up to 36 mW mm-2 after accounting for heating effects. We observe that EPR signal intensities from P1 centers do not follow a Boltzmann trend with laser-induced sample heating. These findings have bearing on the design of diamond-based polarization devices and magnetometry applications.

  6. Internal stress-induced melting below melting temperature at high-rate laser heating

    Science.gov (United States)

    Hwang, Yong Seok; Levitas, Valery I.

    2014-06-01

    In this Letter, continuum thermodynamic and phase field approaches (PFAs) predicted internal stress-induced reduction in melting temperature for laser-irradiated heating of a nanolayer. Internal stresses appear due to thermal strain under constrained conditions and completely relax during melting, producing an additional thermodynamic driving force for melting. Thermodynamic melting temperature for Al reduces from 933.67 K for a stress-free condition down to 898.1 K for uniaxial strain and to 920.8 K for plane strain. Our PFA simulations demonstrated barrierless surface-induced melt nucleation below these temperatures and propagation of two solid-melt interfaces toward each other at the temperatures very close to the corresponding predicted thermodynamic equilibrium temperatures for the heating rate Q ≤1.51×1010K/s. At higher heating rates, kinetic superheating competes with a reduction in melting temperature and melting under uniaxial strain occurs at 902.1 K for Q = 1.51 × 1011 K/s and 936.9 K for Q = 1.46 × 1012 K/s.

  7. Internal stress-induced melting below melting temperature at high-rate laser heating

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Yong Seok, E-mail: yshwang@iastate.edu [Department of Aerospace Engineering, Iowa State University, Ames, Iowa 50011 (United States); Levitas, Valery I., E-mail: vlevitas@iastate.edu [Departments of Aerospace Engineering, Mechanical Engineering, and Material Science and Engineering, Iowa State University, Ames, Iowa 50011 (United States)

    2014-06-30

    In this Letter, continuum thermodynamic and phase field approaches (PFAs) predicted internal stress-induced reduction in melting temperature for laser-irradiated heating of a nanolayer. Internal stresses appear due to thermal strain under constrained conditions and completely relax during melting, producing an additional thermodynamic driving force for melting. Thermodynamic melting temperature for Al reduces from 933.67 K for a stress-free condition down to 898.1 K for uniaxial strain and to 920.8 K for plane strain. Our PFA simulations demonstrated barrierless surface-induced melt nucleation below these temperatures and propagation of two solid-melt interfaces toward each other at the temperatures very close to the corresponding predicted thermodynamic equilibrium temperatures for the heating rate Q≤1.51×10{sup 10}K/s. At higher heating rates, kinetic superheating competes with a reduction in melting temperature and melting under uniaxial strain occurs at 902.1 K for Q = 1.51 × 10{sup 11 }K/s and 936.9 K for Q = 1.46 × 10{sup 12 }K/s.

  8. Laser mass spectrometric detection of extraterrestrial aromatic molecules: mini-review and examination of pulsed heating effects.

    Science.gov (United States)

    Spencer, Maegan K; Hammond, Matthew R; Zare, Richard N

    2008-11-25

    Laser mass spectrometry is a powerful tool for the sensitive, selective, and spatially resolved analysis of organic compounds in extraterrestrial materials. Using microprobe two-step laser mass spectrometry (muL(2)MS), we have explored the organic composition of many different exogenous materials, including meteorites, interplanetary dust particles, and interstellar ice analogs, gaining significant insight into the nature of extraterrestrial materials. Recently, we applied muL(2)MS to analyze the effect of heating caused by hypervelocity particle capture in aerogel, which was used on the NASA Stardust Mission to capture comet particles. We show that this material exhibits complex organic molecules upon sudden heating. Similar pulsed heating of carbonaceous materials is shown to produce an artifactual fullerene signal. We review the use of muL(2)MS to investigate extraterrestrial materials, and we discuss its recent application to characterize the effect of pulsed heating on samples of interest.

  9. Improved identification and quantitation of mature endogenous peptides in the rodent hypothalamus using a rapid conductive sample heating system.

    Science.gov (United States)

    Yang, Ning; Anapindi, Krishna D B; Romanova, Elena V; Rubakhin, Stanislav S; Sweedler, Jonathan V

    2017-11-03

    Measurement, identification, and quantitation of endogenous peptides in tissue samples by mass spectrometry (MS) contribute to our understanding of the complex molecular mechanisms of numerous biological phenomena. For accurate results, it is essential to arrest the postmortem degradation of ubiquitous proteins in samples prior to performing peptidomic measurements. Doing so ensures that the detection of endogenous peptides, typically present at relatively low levels of abundance, is not overwhelmed by protein degradation products. Heat stabilization has been shown to inactivate the enzymes in tissue samples and minimize the presence of protein degradation products in the subsequent peptide extracts. However, the efficacy of different heat treatments to preserve the integrity of full-length endogenous peptides has not been well documented; prior peptidomic studies of heat stabilization methods have not distinguished between the full-length (mature) and numerous truncated (possible artifacts of sampling) forms of endogenous peptides. We show that thermal sample treatment via rapid conductive heat transfer is effective for detection of mature endogenous peptides in fresh and frozen rodent brain tissues. Freshly isolated tissue processing with the commercial Stabilizor T1 heat stabilization system resulted in the confident identification of 65% more full-length mature neuropeptides compared to widely used sample treatment in a hot water bath. This finding was validated by a follow-up quantitative multiple reaction monitoring MS analysis of select neuropeptides. The rapid conductive heating in partial vacuum provided by the Stabilizor T1 effectively reduces protein degradation and decreases the chemical complexity of the sample, as assessed by determining total protein content. This system enabled the detection, identification, and quantitation of neuropeptides related to 22 prohormones expressed in individual rat hypothalami and suprachiasmatic nuclei.

  10. Transient, three-dimensional heat transfer model for the laser assisted machining of silicon nitride: 2. Assessment of parametric effects

    Energy Technology Data Exchange (ETDEWEB)

    Rozzi, J.C.; Shin, Y.C. [Purdue University, (United States). Laser Assisted Materials Processing Laboratory, School of Mechanical Engineering; Incropera, F.P. [University of Notre Dame, (United States). Aerospace and Mechanical Engineering Department

    2000-04-01

    In a companion paper experimental validation was provided for a transient, three-dimensional heat transfer model of the LAM of a silicon nitride workpiece. In this paper, the model is used to elucidate the influence of operating parameters on thermal conditions within the workpiece. Calculations reveal that thermal energy generation in the primary shear zone has a significant influence on the workpiece temperature distribution, while the effects of heat transfer at the tool flank interface may be neglected. Although temperatures at the material removal plane were only moderately influenced by an increase in the workpiece rotational speed, a reduction in total laser energy deposition due to increased laser/tool translational velocity or decreased laser power may preclude the attainment of a minimum material removal temperature corresponding to the softening temperature range of the YSiAlON glassy phase. Due to the comparatively small influence on radial temperature gradients within the material removal plane, the minimum material removal temperature decreased only slightly with increasing depth of cut. However, the amount of laser energy deposition on the unmachined workpiece increased significantly with increasing laser-tool lead distance, yielding an attendant increase in the material removal temperature. For a fixed laser-tool lead, energy deposition at the unmachined workpiece surface increased with decreasing laser beam diameter and increasing power. (author)

  11. Multi-parametric modeling of solid sample heating by nanosecond laser pulses in application for nano-ablation

    Science.gov (United States)

    Semerok, A.; Fomichev, S. V.; Jabbour, C.; Lacour, J.-L.; Tabarant, M.; Chartier, F.

    2017-10-01

    Multi-parametric theoretical studies to analyze the effect of both the matter properties (absorption coefficient, thermal conductivity and diffusivity) and the heating field parameters (spatial distribution and pulse duration) on the resulted temperature distribution are presented. For heating in sub-micrometric range (tip-enhanced near-field ablation (4 ns laser pulse duration, 266 nm wavelength) of Si- and Au-samples.

  12. Saturable absorption of an x-ray free-electron-laser heated solid-density aluminum plasma.

    Science.gov (United States)

    Rackstraw, D S; Ciricosta, O; Vinko, S M; Barbrel, B; Burian, T; Chalupský, J; Cho, B I; Chung, H-K; Dakovski, G L; Engelhorn, K; Hájková, V; Heimann, P; Holmes, M; Juha, L; Krzywinski, J; Lee, R W; Toleikis, S; Turner, J J; Zastrau, U; Wark, J S

    2015-01-09

    High-intensity x-ray pulses from an x-ray free-electron laser are used to heat and probe a solid-density aluminum sample. The photon-energy-dependent transmission of the heating beam is studied through the use of a photodiode. Saturable absorption is observed, with the resulting transmission differing significantly from the cold case, in good agreement with atomic-kinetics simulations.

  13. Rapid nanocrystallization of soft-magnetic amorphous alloys using microwave induction heating

    Energy Technology Data Exchange (ETDEWEB)

    Nicula, R. [Swiss Federal Laboratories for Materials Testing and Research - Empa, Feuerwerkerstr. 39, CH-3602 Thun (Switzerland)], E-mail: radu.nicula@empa.ch; Stir, M.; Ishizaki, K. [Swiss Federal Laboratories for Materials Testing and Research - Empa, Feuerwerkerstr. 39, CH-3602 Thun (Switzerland); Catala-Civera, J.-M. [Polytechnical University of Valencia, School of Telecommunication, Camino de Vera s/n, E-46022 Valencia (Spain); Vaucher, S. [Swiss Federal Laboratories for Materials Testing and Research - Empa, Feuerwerkerstr. 39, CH-3602 Thun (Switzerland)

    2009-01-15

    The crystallization of Fe{sub 73}Nb{sub 3}Cu{sub 1}Si{sub 16}B{sub 7} alloy during microwave heating was investigated in situ using synchrotron radiation powder diffraction. The phase transformation comprises a primary nanocrystallization stage and a final microcrystallization step. We provide evidence for a strong enhancement of the transformation kinetics. Microwave heating occurs as a result of both ohmic and magnetic losses induced by eddy currents, which defines a volumetric microwave induction heating process. Nanocrystallization is completed within 5 s, while full crystallization is achieved in less than 10 s.

  14. Advanced Synchrotron Technique for Synthesis and Analysis of Polyhydrides in the Laser Heated Diamond Anvil Cell

    Science.gov (United States)

    Prakapenka, V.; Struzhkin, V.; Goncharov, A. F.; Greenberg, E.

    2016-12-01

    To understand the complex nature of the deep interior of the terrestrial and giant planets the essential properties of a wide range of minerals must be studied in-situ at relevant ultra-extreme conditions of pressure and temperature. One of the most challenging high pressure high temperature experiments with the diamond anvil cell is related to a laser heating technique combined with synchrotron x-ray diffraction (XRD) and spectroscopy [1]. Especially it is crucial for compression of materials which affect the stability of diamond anvils even at ambient temperature, resulting in experiment failure. Hydrogen and/or alkali metals and their compounds are such examples. Typically, such type of experiments should be carried out at low temperatures in a bulky cryostat with limited flexibility on temperature variation and with restricted optical and x-ray access. At GSECARS we have developed a method that allows us to compress samples at cryo-temperatures while maintaining a relatively short optical working distance to implement laser heating, optical spectroscopy combined with XRD for in-situ high pressure and low/high temperature analysis. We have used an Oxford Cryosteam system to generate a nitrogen jet pointed directly at the sample to cool it down below 150K (typically 115K) as well as to protect the back side of the diamond anvils from frost. While the DAC was kept at cryo-temperatures the "burst" laser heating technique was used to synthesize new compounds and probe in-situ high temperature properties of samples with high resolution synchrotron XRD. With this technique we have successfully studied a number of hydrogen compounds in the megabar pressure range. For example, hydrogen-rich hydrides of Na (NaH3 and NaH7) were synthesized for the first time and studied at pressure-temperature conditions above 30 GPa and 2,000 K [2]. Hydrogen sulfide (H2S) was studied by synchrotron XRD and Raman spectroscopy up to 150 GPa at 180-295 K [3]. The described above new method

  15. QUALITY IMPROVEMENT OF SECONDARY SILUMINS BY USING REFINING-MODIFYING, HEAT AND LASER TREATMENTS

    Directory of Open Access Journals (Sweden)

    I. P. Volchok

    2014-10-01

    Full Text Available Purpose. As a rule secondary silumins are characterized by lower quality than their primary analogues. During manufacture of alloys a large quantity of intermetallides, first of all on the basis of iron, in their structure is ignored. To achieve the optimum level of properties it is necessary to search for ways to adapt refining-modifying, heat and laser treatments to peculiarities of the structure of secondary Al-Si alloys. Methodology. The research was carried out by using standard methods of metallographic analysis, determination of foundry, mechanical and service properties of alloys according to rotatable plans of multifactor experiments. Findings. It was established, that refiningmodifying treatment is a required procedure during manufacture of secondary silumins as it permits to effectively influence the iron-containing phases' segregations by changing their morphology, size and distribution and to increase the effectiveness of further treatment in solid state. It was found that standard modes of heat treatment are not optimal for secondary silumins. Laser treatment has shown high effectiveness in increasing of strength, wear resistance, corrosion and cavitation resistance of secondary Al-Si alloys, and the increased iron content contributed to additional solid solution hardening. Originality. It was established, that after refining-modifying treatment the phase Al5SiFe, which crystallizes in the shape of long stretched plates transformed into phase Al15(FeMn3Si2 in skeletal or polyhedral shape. The relationship between iron content in secondary silumins and holding time during heat treatment that ensures optimum of mechanical properties was obtained. It was proved that the presence of ironcontaining intermetallides Al5SiFe results in the decrease of hardened layer's depth during laser treatment. It was established, that with increasing of iron concentration the corrosion rate of secondary silumins in 3 % NaCl + 0.1 % H2O2 and 10 % HCl

  16. 3D noninvasive, high-resolution imaging using a photoacoustic tomography (PAT) system and rapid wavelength-cycling lasers

    Science.gov (United States)

    Sampathkumar, Ashwin; Gross, Daniel; Klosner, Marc; Chan, Gary; Wu, Chunbai; Heller, Donald F.

    2015-05-01

    Globally, cancer is a major health issue as advances in modern medicine continue to extend the human life span. Breast cancer ranks second as a cause of cancer death in women in the United States. Photoacoustic (PA) imaging (PAI) provides high molecular contrast at greater depths in tissue without the use of ionizing radiation. In this work, we describe the development of a PA tomography (PAT) system and a rapid wavelength-cycling Alexandrite laser designed for clinical PAI applications. The laser produces 450 mJ/pulse at 25 Hz to illuminate the entire breast, which eliminates the need to scan the laser source. Wavelength cycling provides a pulse sequence in which the output wavelength repeatedly alternates between 755 nm and 797 nm rapidly within milliseconds. We present imaging results of breast phantoms with inclusions of different sizes at varying depths, obtained with this laser source, a 5-MHz 128-element transducer and a 128-channel Verasonics system. Results include PA images and 3D reconstruction of the breast phantom at 755 and 797 nm, delineating the inclusions that mimic tumors in the breast.

  17. Rapid Detection of OXA-48-Producing Enterobacteriaceae by Matrix-Assisted Laser Desorption Ionization−Time of Flight Mass Spectrometry

    Science.gov (United States)

    Oviaño, Marina; Barba, Maria José; Fernández, Begoña; Ortega, Adriana; Aracil, Belén; Oteo, Jesús; Campos, José

    2015-01-01

    A rapid and sensitive (100%) matrix-assisted laser desorption ionization−time of flight mass spectrometry (MALDI-TOF MS) assay was developed to detect OXA-48-type producers, using 161 previously characterized clinical isolates. Ertapenem was monitored to detect carbapenem resistance, and temocillin was included in the assay as a marker for OXA-48-producers. Structural analysis of temocillin is described. Data are obtained within 60 min. PMID:26677247

  18. Parametric investigation on transient boiling heat transfer of metal rod cooled rapidly in water pool

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Chi Young [Department of Fire Protection Engineering, Pukyong National University, 45, Yongso-ro, Nam-gu, Busan 48513 (Korea, Republic of); Kim, Sunwoo, E-mail: swkim@alaska.edu [Mechanical Engineering Department, University of Alaska Fairbanks, P. O. Box 755905, Fairbanks, AK 99775-5905 (United States)

    2017-03-15

    Highlights: • Effects of liquid subcooling, surface coating, material property, and surface oxidation are examined. • Liquid subcooling affects remarkably the quenching phenomena. • Cr-coated surfaces for ATF might extend the quenching duration. • Solids with low heat capacity shorten the quenching duration. • Surface oxidation can affect strongly the film boiling heat transfer and MFB point. - Abstract: In this work, the effects of liquid subcooling, surface coating, material property, and surface oxidation on transient pool boiling heat transfer were investigated experimentally using the vertical metal rod and quenching method. The change in rod temperature was measured with time during quenching, and the visualization of boiling around the test specimen was performed using the high-speed video camera. As the test materials, the zircaloy (Zry), stainless steel (SS), niobium (Nb), and copper (Cu) were tested. In addition, the chromium-coated niobium (Cr-Nb) and chromium-coated stainless steel (Cr-SS) were prepared for accident tolerant fuel (ATF) application. Low liquid subcooling and Cr-coating shifted the quenching curve to the right, which indicates a prolongation of quenching duration. On the other hand, the material with small heat capacity and surface oxidation caused the quenching curve to move to the left. To examine the influence of the material property and surface oxidation on the film boiling heat transfer performance and minimum film boiling (MFB) point in more detail, the wall temperature and heat flux were calculated from the present transient temperature profile using the inverse heat transfer analysis, and then the curves of wall temperature and heat flux in the film boiling regime were obtained. In the present experimental conditions, the effect of material property on the film boiling heat transfer performance and MFB point seemed to be minor. On the other hand, based on the experimental results of the Cu test specimen, the surface

  19. Development of Rapid Pipe Moulding Process for Carbon Fiber Reinforced Thermoplastics by Direct Resistance Heating

    Science.gov (United States)

    Tanaka, Kazuto; Harada, Ryuki; Uemura, Toshiki; Katayama, Tsutao; Kuwahara, Hideyuki

    To deal with environmental issues, the gasoline mileage of passenger cars can be improved by reduction of the car weight. The use of car components made of Carbon Fiber Reinforced Plastics (CFRP) is increasing because of its superior mechanical properties and relatively low density. Many vehicle structural parts are pipe-shaped, such as suspension arms, torsion beams, door guard bars and impact beams. A reduction of the car weight is expected by using CFRP for these parts. Especially, when considering the recyclability and ease of production, Carbon Fiber Reinforced Thermoplastics are a prime candidate. On the other hand, the moulding process of CFRTP pipes for mass production has not been well established yet. For this pipe moulding process an induction heating method has been investigated already, however, this method requires a complicated coil system. To reduce the production cost, another system without such complicated equipment is to be developed. In this study, the pipe moulding process of CFRTP using direct resistance heating was developed. This heating method heats up the mould by Joule heating using skin effect of high-frequency current. The direct resistance heating method is desirable from a cost perspective, because this method can heat the mould directly without using any coils. Formerly developed Non-woven Stitched Multi-axial Cloth (NSMC) was used as semi-product material. NSMC is very suitable for the lamination process due to the fact that non-crimp stitched carbon fiber of [0°/+45°/90°/-45°] and polyamide 6 non-woven fabric are stitched to one sheet, resulting in a short production cycle time. The use of the pipe moulding process with the direct resistance heating method in combination with the NSMC, has resulted in the successful moulding of a CFRTP pipe of 300 mm in length, 40 mm in diameter and 2 mm in thickness.

  20. Numerical simulations on conformable laser-induced interstitial thermotherapy through combined use of multi-beam heating and biodegradable nanoparticles.

    Science.gov (United States)

    Zhang, Jie; Jin, Chao; He, Zhi-Zhu; Liu, Jing

    2014-07-01

    Clinically, precisely heating and thus completely ablating diseased tumor tissue through laser beam is still facing many technical challenges. In this study, numerical simulation of a conformal heating modality based on multi-beam laser along with biodegradable magnesium nanoparticles (Mg-NPs) was put forward to treat liver tumor with large size or irregular shape. Further, a Gaussian-like distribution was proposed to investigate the influence of Mg-NP deposition on the nanoenhanced laser-induced interstitial thermotherapy (LITT). A temperature feedback system was adopted to control the temperature range to avoid overheating. To preliminarily validate the heating enhancement induced by the applied multi-beam laser and Mg-NPs, a conceptual experiment was performed. Both theoretical simulation and experimental measurements demonstrated that multi-beam laser with Mg-NPs could improve efficiency in the conformal heating of tumors with irregular shape or large size. In addition, the distribution and content of Mg-NPs produced significant impact on thermotherapy: (1) The adjustable parameter σ in the Gaussian-like distribution could reflect various practical situations and diffusivities of Mg-NPs; (2) under the premise of the same concentration of Mg-NPs and short time to heat a small-sized target, the whole liver tumor containing Mg-NPs could not improve the efficiency as the nanoparticles limited the photons to be absorbed only around the fibers, while liver tumor partially containing Mg-NPs could improve the thermotherapy efficiency up to 20 %; and (3) the addition of Mg-NPs was rather beneficial for realizing a conformal heating as the residual thermal energy was much less than that without Mg-NPs. This study suggests a feasible and promising modality for planning a high-performance LITT in future clinics.

  1. Effect of Heat Input During Disk Laser Bead-On-Plate Welding of Thermomechanically Rolled Steel on Penetration Characteristics and Porosity Formation in the Weld Metal

    Directory of Open Access Journals (Sweden)

    Lisiecki A.

    2016-03-01

    Full Text Available The paper presents a detailed analysis of the influence of heat input during laser bead-on-plate welding of 5.0 mm thick plates of S700MC steel by modern Disk laser on the mechanism of steel penetration, shape and depth of penetration, and also on tendency to weld porosity formation. Based on the investigations performed in a wide range of laser welding parameters the relationship between laser power and welding speed, thus heat input, required for full penetration was determined. Additionally the relationship between the laser welding parameters and weld quality was determined.

  2. Rapidly developed squamous cell carcinoma after laser therapy used to treat chemical burn wound: a case report.

    Science.gov (United States)

    Cho, Hyung-Rok; Kwon, Soon-Sung; Chung, Seum; Kie, Jeong-Hae

    2015-02-07

    In chronic wounds, especially burn scars, malignant tumors can arise. However, it is rare for a subacute burn injury to change to a malignant lesion within one month. Moreover, a case of squamous cell carcinoma arising from HeNe laser therapy after a chemical burn has never been reported. In this report, we examine a rare case of squamous cell carcinoma arising from HeNe laser therapy after a chemical burn. Because pathologic investigations were made from the first operation, both early detection of the squamous cell carcinoma and consideration of the HeNe laser therapy as a risk factor for the skin cancer were possible. The cancer was completely removed and reconstruction of the defect was successfully achieved in a timely manner. Although there has as yet been no reported case of squamous cell carcinoma induced by laser therapy, it is important for clinicians to recognize both the possibility of laser-induced cancer and the rapid change of cancer, so they can provide appropriate and timely treatment.

  3. Rapid fabrication of mesoporous TiO2 thin films by pulsed fibre laser for dye sensitized solar cells

    Science.gov (United States)

    Hadi, Aseel; Alhabradi, Mansour; Chen, Qian; Liu, Hong; Guo, Wei; Curioni, Michele; Cernik, Robert; Liu, Zhu

    2018-01-01

    In this paper we demonstrate for the first time that a fibre laser with a wavelength of 1070 nm and a pulse width of milliseconds can be applied to generate mesoporous nanocrystalline (nc) TiO2 thin films on ITO coated glass in ambient atmosphere, by complete vaporisation of organic binder and inter-connection of TiO2 nanoparticles, without thermally damaging the ITO layer and the glass substrate. The fabrication of the mesoporous TiO2 thin films was achieved by stationary laser beam irradiation of 1 min. The dye sensitized solar cell (DSSC) with the laser-sintered TiO2 photoanode reached higher power conversion efficiency (PCE) of 3.20% for the TiO2 film thickness of 6 μm compared with 2.99% for the furnace-sintered. Electrochemical impedance spectroscopy studies revealed that the laser sintering under the optimised condition effectively decreased charge transfer resistance and increased electron lifetime of the TiO2 thin films. The use of the fibre laser with over 40% wall-plug efficiency offers an economically-feasible, industrial viable solution to the major challenge of rapid fabrication of large scale, mass production of mesoporous metal oxide thin film based solar energy systems, potentially for perovskite and monolithic tandem solar cells, in the future.

  4. Monitoring Delamination of Thermal Barrier Coatings During Interrupted High-Heat-Flux Laser Testing using Luminescence Imaging

    Science.gov (United States)

    Eldridge, Jeffrey I.; Zhu, Dongming; Wolfe, Douglas E.

    2011-01-01

    This presentation showed progress made in extending luminescence-base delamination monitoring to TBCs exposed to high heat fluxes, which is an environment that much better simulates actual turbine engine conditions. This was done by performing upconversion luminescence imaging during interruptions in laser testing, where a high-power CO2 laser was employed to create the desired heat flux. Upconverison luminescence refers to luminescence where the emission is at a higher energy (shorter wavelength) than the excitation. Since there will be negligible background emission at higher energies than the excitation, this methods produces superb contrast. Delamination contrast is produced because both the excitation and emission wavelengths are reflected at delamination cracks so that substantially higher luminescence intensity is observed in regions containing delamination cracks. Erbium was selected as the dopant for luminescence specifically because it exhibits upconversion luminescence. The high power CO2 10.6 micron wavelength laser facility at NASA GRC was used to produce the heat flux in combination with forced air backside cooling. Testing was performed at a lower (95 W/sq cm) and higher (125 W/sq cm) heat flux as well as furnace cycling at 1163C for comparison. The lower heat flux showed the same general behavior as furnace cycling, a gradual, "spotty" increase in luminescence associated with debond progression; however, a significant difference was a pronounced incubation period followed by acceleration delamination progression. These results indicate that extrapolating behavior from furnace cycling measurements will grossly overestimate remaining life under high heat flux conditions. The higher heat flux results were not only accelerated, but much different in character. Extreme bond coat rumpling occurred, and delamination propagation extended over much larger areas before precipitating macroscopic TBC failure. This indicates that under the higher heat flux (and

  5. Automatic diameter control system applied to the laser heated pedestal growth technique

    Directory of Open Access Journals (Sweden)

    Andreeta M.R.B.

    2003-01-01

    Full Text Available We described an automatic diameter control system (ADC, for the laser heated pedestal growth technique, that reduces the diameter fluctuations in oxide fibers grown from unreacted and non-sinterized pedestals, to less than 2% of the average fiber diameter, and diminishes the average diameter fluctuation, over the entire length of the fiber, to less than 1%. The ADC apparatus is based on an artificial vision system that controls the pulling speed and the height of the molten zone within a precision of 30 mum. We also show that this system can be used for periodic in situ axial doping the fiber. Pure and Cr3+ doped LaAlO3 and pure LiNbO3 were usedas model materials.

  6. Aerodynamic levitation and laser heating: Applications at synchrotron and neutron sources

    Energy Technology Data Exchange (ETDEWEB)

    Hennet, L.; Pozdnyakova, I.; Drewitt, J.W.E.; Leydier, M.; Brassamin, S.; Zanghi, D.; Magazu, S.; Price, D.L. [CEMHTI and University of Orleans, 45071 Orleans Cedex 02 (France); Cristiglio, V.; Kozaily, J.; Fischer, H.E.; Cuello, G.J.; Koza, M. [ILL, BP. 156, 38042 Grenoble Cedex 09 (France); Bytchkov, A. [ESRF, BP. 220, 38043 Grenoble Cedex 09 (France); Thiaudiere, D. [Synchrotron SOLEIL, BP. 48, 91192 Gif-sur-Yvette Cedex (France); Gruner, S. [Institute of Physics, Chemnitz UT, 09107 Chemnitz (Germany); Greaves, G.N. [IMAPS, University of Wales, Aberystwyth, SY23 3BZ (United Kingdom)

    2011-05-15

    Aerodynamic levitation is an effective way to suspend samples which can be heated with CO{sub 2} lasers. The advantages of this container-less technique are the simplicity and compactness of the device, making it possible to integrate it easily in different kinds of experiments. In addition, all types of materials can be used, including metals and oxides. The integration of aerodynamic levitation at synchrotron and neutron sources provides powerful tools to study the structure and dynamics of molten materials. We present here an overview of the existing techniques (electromagnetic levitation, electrostatic levitation, single-axis acoustic levitation, and aerodynamic levitation) and of the developments made at the CEMHTI in Orleans, as well as a few examples of experimental results already obtained. (authors)

  7. Synthesis of Non-molecular Nitrogen Phases at Mbar Pressures by Direct Laser-heating

    Energy Technology Data Exchange (ETDEWEB)

    Lipp, M J; Klepeis, J P; Baer, B J; Cynn, H; Evans, W J; Iota, V; Yoo, C

    2007-03-26

    Direct laser heating of molecular N2 to above 1400 K at 120-130 GPa results in the formation of a reddish amorphous phase and a transparent crystalline solid above 2000 K. Raman and x-ray data confirm that the transparent phase is cubic-gauche nitrogen (cg-N), while the reddish color of the amorphous phase might indicate the presence of N=N dish bonds. The quenched amorphous phase is stable down to at least 70GPa, analogous to cg-N, and could be a new non-molecular phase or an extension of the already known {eta}-phase. A chemo-physical phase diagram is presented which emphasizes the difference between pressure- and temperature-induced transitions from molecular to non-molecular solids, as found in other low Z systems.

  8. Large spectral tuning of liquid microdroplets by local heating with a focused infrared laser

    Science.gov (United States)

    Kiraz, Alper; Karadağ, Yasin; Yorulmaz, Saime Ç.; Muradoğlu, Metin

    2008-08-01

    Large deformations can easily be introduced in liquid microdroplets by applying relatively small external forces or controlling the evaporation/condensation kinetics. This makes liquid microdroplets attractive to serve as the building blocks of largely tunable optical switches or filters that are essential in optical communication systems based on wavelength division multiplexing. Solid optical microcavities have not found large use in these applications, mainly due to their rigid nature. The fact that liquid microdroplets are low-cost and disposable can also prove to be important in mass production of these photonic devices. Here, we show that local heating with an infrared laser can be used to largely tune the whispering gallery modes (WGMs) of water/glycerol or salty water microdroplets standing on a superhydrophobic surface. In the scheme presented, a liquid microdroplet kept in a humidity chamber is stabilized on a superhydrophobic surface, and an infrared laser beam is focused near the center of the microdroplet. As a result of the local heating, the temperature of the liquid microdroplet increases, and the water content in the liquid microdroplet evaporates until a new equilibrium is reached. At the new equilibrium state, the non-volatile component (i.e. glycerol or salt) attains a higher concentration in the liquid microdroplet. We report tunability over large spectral ranges up to 30 nm at around 590 nm. For salty water microdroplets the reported spectral tuning mechanism is almost fully reversible, while for the case of glycerol/water microdroplets the spectral tuning mechanism can be made highly reversible when the chamber is saturated with glycerol vapor and the relative water humidity approaches unity.

  9. Graded Reflectivity Mirror for the Solid State Heat Capacity Laser Final Report CRADA No. TC-2085-04

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Davis, J. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-09-27

    This was a collaborative effort between The Regents of the University of California, Lawrence Livermore National Laboratory (LLNL) and the Boeing Company, to develop a Graded Reflectivity Mirror (GRM) to achieve improved near field fill and higher brightness in the far field output of LLNL’s Solid State Heat Capacity Laser (SSHCL).

  10. Effects of heat-treatment on the microstructure of TiAl-Nb produced with laser metal deposition technique

    CSIR Research Space (South Africa)

    Tlotleng, Monnamme

    2017-10-01

    Full Text Available additive manufacturing approach, and the impact of heat treatment on microstructural evolution and hardness measurements. Ti-33Al-8Nb alloy was produced by melting the elemental powders in a laser melt-pool. The resulting microstructure was characterised...

  11. The solidification behaviour of the UO2–ThO2 system in a laser heating study

    NARCIS (Netherlands)

    Böhler, R.; Quaini, A.; Capriotti, L.; Cakir, P.; Benes, O.; Boboridis, K.; Guiot, A.; Luzzi, L.; Konings, R.J.M.; Manara, D.

    2014-01-01

    The high-temperature phase diagram of the UO2–ThO2 system has been experimentally revisited in the present study for the first time since 1970, using a laser heating approach combined with fast pyrometry in a thermal arrest method. The melting/solidification temperature, which is of fundamental

  12. Application of Mobile Laser Scanning for Lean and Rapid Highway Maintenance and Construction

    Science.gov (United States)

    2015-08-28

    Mobile Terrestrial Laser Scanning (MTLS) is an emerging technology that combines the use of a laser scanner(s), the Global Navigation Satellite System (GNSS), and an Inertial Measurement Unit (IMU) on a vehicle to collect geo-spatial data. The overal...

  13. Measurement of residual radioactive surface contamination by 2-D laser heated TLD

    Energy Technology Data Exchange (ETDEWEB)

    Jones, S.C.

    1997-06-01

    The feasibility of applying and adapting a two-dimensional laser heated thermoluminescence dosimetry system to the problem of surveying for radioactive surface contamination was studied. The system consists of a CO{sub 2} laser-based reader and monolithic arrays of thin dosimeter elements. The arrays consist of 10,201 thermoluminescent phosphor elements of 40 micron thickness, covering a 900 cm{sup 2} area. Array substrates are 125 micron thick polyimide sheets, enabling them to easily conform to regular surface shapes, especially for survey of surfaces that are inaccessible for standard survey instruments. The passive, integrating radiation detectors are sensitive to alpha and beta radiation at contamination levels below release guideline limits. Required contact times with potentially contaminated surfaces are under one hour to achieve detection of transuranic alpha emission at 100 dpm/100 cm{sup 2}. Positional information obtained from array evaluation is useful for locating contamination zones. Unique capabilities of this system for survey of sites, facilities and material include measurement inside pipes and other geometrical configurations that prevent standard surveys, and below-surface measurement of alpha and beta emitters in contaminated soils. These applications imply a reduction of material that must be classified as radioactive waste by virtue of its possibility of contamination, and cost savings in soil sampling at contaminated sites.

  14. Thermal signature measurements for ammonium nitrate/fuel mixtures by laser heating

    Energy Technology Data Exchange (ETDEWEB)

    Nazarian, Ashot; Presser, Cary, E-mail: cpresser@nist.gov

    2016-01-10

    Highlights: • LDTR is a useful diagnostic for characterizing AN/fuel mixture thermochemical behavior. • Each AN/fuel mixture thermal signature was different. • AN/fuel mixture signature features were defined by the individual constituents. • Baseline signatures changed after an experiment. - Abstract: Measurements were carried out to obtain thermal signatures of several ammonium nitrate/fuel (ANF) mixtures, using a laser-heating technique referred to as the laser-driven thermal reactor (LDTR). The mixtures were ammonium nitrate (AN)/kerosene, AN/ethylene glycol, AN/paraffin wax, AN/petroleum jelly, AN/confectioner's sugar, AN/cellulose (tissue paper), nitromethane/cellulose, nitrobenzene/cellulose, AN/cellulose/nitromethane, AN/cellulose/nitrobenzene. These mixtures were also compared with AN/nitromethane and AN/diesel fuel oil, obtained from an earlier investigation. Thermograms for the mixtures, as well as individual constituents, were compared to better understand how sample thermal signature changes with mixture composition. This is the first step in development of a thermal-signature database, to be used along with other signature databases, to improve identification of energetic substances of unknown composition. The results indicated that each individual thermal signature was associated unambiguously with a particular mixture composition. The signature features of a particular mixture were shaped by the individual constituent signatures. It was also uncovered that the baseline signature was modified after an experiment due to coating of unreacted residue on the substrate surface and a change in the reactor sphere oxide layer. Thus, care was required to pre-oxidize the sphere prior to an experiment. A minimum sample mass (which was dependent on composition) was required to detect the signature characteristics. Increased laser power served to magnify signal strength while preserving the signature features. For the mixtures examined, the thermal

  15. A high repetition rate TEA CO II laser operating at λ=9.3-μm for the rapid and conservative ablation and modification of dental hard tissues

    Science.gov (United States)

    Fan, Kenneth; Fried, Daniel

    2006-02-01

    TEA CO II lasers tuned to the strong mineral absorption of hydroxyapatite near λ=9-μm are ideally suited for the efficient ablation of dental hard tissues if the laser-pulse is stretched to greater than 5-10-μs to avoid plasma shielding phenomena. Such CO II lasers are capable of operating at high repetition rates for the rapid removal of dental hard tissues. An Impact 2500 TEA CO II laser system from GSI Lumonics (Rugby, UK) custom modified by LightMachinery (Ottawa, Canada) with a repetition rate of 0-500 Hz was used for rapid tissue removal. The single pulse ablation rates through enamel were determined for incident fluence ranging from (1-160 J/cm2). Lateral incisions using a computer controlled scanning stage and water spray were produced and the crater morphology and chemical composition were measured using optical microscopy and high-resolution synchrotron radiation infrared spectromicroscopy. The transmission through 2-meter length 300, 500, 750 and 1000-μm silica hollow waveguides was measured and 80% transmission was achieved with 40-mJ per pulse. The λ=9.3-μm laser pulses efficiently removed dental enamel at rates exceeding 15-μm per pulses with minimal heat accumulation. The residual energy remaining in tooth samples was measured to be 30-40% without water cooling, significantly lower than for longer CO II laser pulses. These results suggest that high repetition rate TEA CO II laser systems operating at λ=9.3-μm with pulse durations of 10-20-μs are ideally suited for dental application.

  16. Low heat flow from young oceanic lithosphere at the Middle America Trench off Mexico [rapid communication

    Science.gov (United States)

    Minshull, Timothy A.; Bartolomé, Rafael; Byrne, Siobhán; Dañobeitia, Juanjo

    2005-10-01

    Seismic reflection profiles across the Middle America Trench at 20°N show a high amplitude bottom simulating reflector interpreted as marking a phase transition between methane hydrate and free gas in the pore space of both accreted and trench sediments. We determine the depth of the hydrate-gas phase boundary in order to estimate the geothermal gradient and hence the heat flow beneath the trench and the frontal part of the accretionary wedge which overlies the downgoing plate. After correction for sedimentation, heat flow values in the trench and through the accretionary wedge are only about half of the values predicted by plate cooling models for the 10 Ma subducting lithosphere. There is no systematic correlation between heat flow in the accretionary wedge and distance from the trench. A comparison with heat flow predicted by a simple analytical model suggests that there is little shear heating from within or beneath the wedge, despite the high basal friction suggested by the large taper angle of the wedge. The geothermal gradient varies systematically along the margin and is negatively correlated with the frontal slope of the wedge. Some local peaks may be attributed to channelised fluid expulsion.

  17. The influence of laser heat treatment on the geometric structure of the surface and condition of the surface layer and selected properties of Waspaloy

    Directory of Open Access Journals (Sweden)

    Bartkowska Aneta

    2017-01-01

    Full Text Available In the aviation industry the nickel-based superalloys such as Waspaloy are very often used. Conventional machining of this alloys is difficult and expensive. Therefore a Waspaloy requires the new techniques for machining like e.g. Laser Assisted Machining (LAM. New development directions of mechanical engineering are focusing on this type of hybrid machining, where materials are heated and cut in the single process. LAM enables increasing the material machinability through the increase of its temperature in cutting zone. It is assumed that additional increased temperature in the contact zone between surface of material and cutting tool causes the increase of machinability. This paper presents the results of laser heat treatment process on Waspaloy material. The influence of laser heat treatment parameters on the surface condition and selected properties of Waspaloy were analyzed. Laser heat treatment was carried out using diode laser with nominal power equaled to 3.0 kW. The laser beam power density and its scanning laser beam velocity were analyzed. In the first step the single laser tracks were prepared and analyzed. In the second step the multiple laser tracks were prepared. The special attention was directed on change in microstructure. It was found that the laser heat treatment have significant influence on microstructure. The dendritic microstructure of Waspaloy which is characterized by a lower microhardness, causes better machinability of this material.

  18. Peculiar features of boron distribution in high temperature fracture area of rapidly quenched heat-resistant nickel alloy

    Energy Technology Data Exchange (ETDEWEB)

    Shulga, A. V., E-mail: avshulga@mephi.ru [National Research Nuclear University MEPhI (Russian Federation)

    2016-12-15

    This article comprises the results of comprehensive study of the structure and distribution in the high temperature fracture area of rapidly quenched heat-resistant superalloy of grade EP741NP after tensile tests. The structure and boron distribution in the fracture area are studied in detail by means of direct track autoradiography in combination with metallography of macro- and microstructure. A rather extensive region of microcracks generation and intensive boron redistribution is detected in the high temperature fracture area of rapidly quenched nickel superalloy of grade EP741NP. A significant decrease in boron content in the fracture area and formation of elliptically arranged boride precipitates are revealed. The mechanism of intense boron migration and stability violation of the structural and phase state in the fracture area of rapidly quenched heat-resistant nickel superalloy of grade EP741NP is proposed on the basis of accounting for deformation occurring in the fracture area and analysis of the stressed state near a crack.

  19. Investigation of char strength and expansion properties of an intumescent coating exposed to rapid heating rates

    DEFF Research Database (Denmark)

    Nørgaard, Kristian Petersen; Dam-Johansen, Kim; Català, Pere

    2013-01-01

    , char properties, measured at room temperature, were dependent on the preceding storage conditions (in air or in a desiccator). The char was found to have the highest mechanical strength against compression in the outer crust facing the heat source. For thin (147μm) free coating films, a tendency...... with respect to the mechanical resistance against compression, degree of expansion, and residual mass fraction. Experimental results show that when using this type of shock heating, the mechanical resistance of the char against compression cannot meaningfully be correlated to the expansion factor. In addition...

  20. The Effect of Local Heating by Laser Irradiation for Aluminum, Deep Drawing Steel and Copper Sheets in Incremental Sheet Forming

    Science.gov (United States)

    Lehtinen, Pekka; Väisänen, Tapio; Salmi, Mika

    Incremental sheet forming is a technique where a metal sheet is formed into a product usually by a CNC-controlled (Computer Numerical Control) round tipped tool. The part is formed as the tool indents into the sheet and follows a contour of the desired product. In single point incremental forming (SPIF) there is no need for tailored tools and dies, since the process requires only a CNC machine, a clamping rig and a simple tool. The effect of applying local heating by laser irradiation from the bottom side of the metal sheet is investigated with a SPIF approach. Using a laser light source for local heating should increase the material ductility and decrease material strength, and thus, increase the formability. The research was performed using 0.50-0.75 mm thick, deep drawing steel, aluminum and copper sheets. The forming was done with a round tipped tool, whose tip diameter was 4 mm. In order to achieve selective heating, a 1 kW fiber laser was attached to a 3-axis stepper motor driven CNC milling machine. The results show that the applied heating increased the maximum achievable wall angle of aluminum and copper products. However, for the steel sheets the local heating reduced the maximum achievable wall angle and increased the surface roughness.

  1. Laser endoscopy.

    Science.gov (United States)

    McElvein, R B

    1981-11-01

    A carbon dioxide laser operating in the invisible infrared range (10.6 mu) generates a beam of energy that is almost completely absorbed by biological tissue with release of intense heat and rapid destruction. A laser attached to a rigid bronchoscope has been used in 18 patients ranging in age from 21 to 62 years to treat a variety of causes of airway obstruction. These include tracheal stenosis and granulation tissue (6 patients), adenoma (1), web (2), and carcinoma (9). The results were good in 15 and poor in 3 patients. However, all patients had an improved airway after laser treatment with the best results occurring in patients with benign, inflammatory disease. The advantages of the laser are a lack of bleeding, minimal edema after treatment, and minimal scar formation. The disadvantages are the expense of the machine, and the need for general anesthesia and direct visualization of the lesion.

  2. Measurement of the Nonlinearity of Heat-Flux Sensors Employing a CO_2 laser

    Science.gov (United States)

    van der Ham, E. W. M.; Beer, C. M.; Ballico, M. J.

    2018-01-01

    Heat-flux sensors are widely used in industry to test building products and designs for resistance to bushfire, to test the flammability of textiles and in numerous applications such as concentrated solar collectors. In Australia, such detectors are currently calibrated by the National Measurement Institute Australia (NMIA) at low flux levels of 20 W \\cdot m^{-2}. Estimates of the uncertainty arising from nonlinearity at industrial levels (e.g. 50 kW \\cdot m^{-2} for bushfire testing) rely on literature information. NMIA has developed a facility to characterize the linearity response of these heat-flux sensors up to 110 kW \\cdot m^{-2} using a low-power CO_2 laser and a chopped quartz tungsten-halogen lamp. The facility was validated by comparison with the conventional flux-addition method, and used to characterize several Schmidt-Boelter-type sensors. A significant nonlinear response was found, ranging from (3.2 ± 0.9)% at 40 kW \\cdot m^{-2} to more than 8 % at 100 kW \\cdot m^{-2}. Additional measurements confirm that this is not attributable to convection effects, but due to the temperature dependence of the sensor's responsivity.

  3. Microstructure and mechanical property in heat affected zone (HAZ in F82H jointed with SUS316L by fiber laser welding

    Directory of Open Access Journals (Sweden)

    S. Kano

    2016-12-01

    Full Text Available This study investigates the microstructure and mechanical property in heat affected zone (HAZ between F82H and SUS316L jointed by 4 kW fiber laser welding at different parameters such as laser scan rate and beam position. OM/FE-SEM observation, EPMA analysis and nano-indentation hardness test were utilized to characterize the microstructure and evaluate the mechanical property. Results show that the HAZ width is dependent on the welding condition. The precipitation of M23C6 particle in HAZ is found to be closely related to the distance from WM/HAZ interface. Decrease in Cr and C concentration in M23C6 depended on the welding condition; the decrease was relatively milder in the case of shifting the beam position to SUS side. Furthermore, the rapid increment in nano-indentation hardness, i.e. ≈2500 MPa, at HAZ/F82H interface was observed regardless of welding parameters. The temperatures at HAZ/F82H interface were estimated from Cr and C concentration change of M23C6 by EPMA. It was revealed that the temperature of HAZ/F82H interface increased with increasing HAZ width, and that the presence of over-tempered HAZ (THAZ region is confirmed only in the specimens welded right on the F82H/SUS interface (no-shift at the laser scan rate of 3 m/min.

  4. Rapid killing of bed bugs (Cimex lectularius L.) on surfaces using heat: application to luggage.

    Science.gov (United States)

    Loudon, Catherine

    2017-01-01

    The resistance of bed bugs (Cimex lectularius L.) to chemical insecticides has motivated the development of non-chemical control methods such as heat treatment. However, because bed bugs tend to hide in cracks or crevices, their behavior incidentally generates a thermally insulated microenvironment for themselves. Bed bugs located on the outer surface of luggage are less insulated and potentially more vulnerable to brief heat treatment. Soft-sided suitcases with adult male bed bugs on the outside were exposed to an air temperature of 70-75 °C. It took 6 min to kill all of the bed bugs, even those that had concealed themselves under zipper flaps or decorative piping. During heating, only one bed bug (out of 250 in total) moved into the luggage (through a closed zipper). Over long periods of time (24 h) at room temperature, adult male bed bugs on the exterior of luggage only infrequently moved inside; only 3% (5/170) had moved inside during 24 h. Brief exterior heat treatment of luggage is a promising way to reduce the spread of bed bugs being transported on the outer surface of luggage. This treatment will not kill bed bugs inside the luggage, but could be a component of integrated management for this pest. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  5. Transformation Heat Treatment of Rapidly Quenched Nb3A1 Precursor Monitored in situ by High Energy Synchrotron Diffraction

    CERN Document Server

    Scheuerlein, C; Di Michiel, M; Jin, X; Takeuchi, T; Kikuchi, A; Tsuchiya, K; Nakagawa, K; Nakamoto, T

    2013-01-01

    Nb3Al superconductors are studied for use in high field magnets. Fine grained Nb3Al with nearly stoichiometric Al content is obtained by a Rapid Heating Quenching and Transformation (RHQT) process. We describe a non destructive in situ study of the transformation process step of a RHQ Nb3Al precursor wire with ramp rates of either 120 °C/h or 800 °C/h. High energy synchrotron x-ray diffraction measurements show the transformation from a Nb(Al)SS supersaturated solid solution into Nb3Al. When heating with a ramp rate of 120 °C/h a strong reduction of the Nb(Al)SS (110) diffraction peak component is observed when the temperature exceeds 660 °C. Additional diffraction peaks are detectable in the approximate temperature interval 610 °C - 750 °C and significant Nb3Al growth is observed above 730 °C.

  6. Evaluation of Ti(3)Si Phase Stability from Heat-Treated, Rapidly Solidified Ti-Si Alloys

    OpenAIRE

    COSTA, Alex Matos da Silva; de Lima, Gisele Ferreira; Rodrigues,Geovani; NUNES, Carlos Angelo; Coelho,Gilberto Carvalho; Suzuki, Paulo Atsushi

    2010-01-01

    Ti-base alloys containing significant amounts of silicon have been considered for high temperature structural applications. Thus, information concerning phase stability on the Ti-Si system is fundamental and there are not many investigations covering the phase stability of the Ti(3)Si phase, specially its dependence on oxygen/nitrogen contamination. In this work the stability of this phase has been evaluated through heat-treatment of rapidly solidified Ti-rich Ti-Si alloys at 700 A degrees C ...

  7. RAPID COMMUNICATION: Fine-hole drilling in Upilex polyimide and glass by TEA ? laser ablation

    Science.gov (United States)

    Dyer, P. E.; Waldeck, I.; Roberts, G. C.

    1997-03-01

    Small-scale hole formation in Upilex polyimide and soda-lime glass using TEA 0022-3727/30/6/003/img2 laser ablation is reported. Hole dimensions as small as 0022-3727/30/6/003/img3 produced in the polyimide suggest optical resolution rather than thermal degradation effects limit the feature size attainable in infrared TEA 0022-3727/30/6/003/img2 laser polymer ablation.

  8. Temperature and humidity based projections of a rapid rise in global heat stress exposure during the 21st century

    Science.gov (United States)

    Coffel, Ethan D.; Horton, Radley M.; de Sherbinin, Alex

    2018-01-01

    As a result of global increases in both temperature and specific humidity, heat stress is projected to intensify throughout the 21st century. Some of the regions most susceptible to dangerous heat and humidity combinations are also among the most densely populated. Consequently, there is the potential for widespread exposure to wet bulb temperatures that approach and in some cases exceed postulated theoretical limits of human tolerance by mid- to late-century. We project that by 2080 the relative frequency of present-day extreme wet bulb temperature events could rise by a factor of 100–250 (approximately double the frequency change projected for temperature alone) in the tropics and parts of the mid-latitudes, areas which are projected to contain approximately half the world’s population. In addition, population exposure to wet bulb temperatures that exceed recent deadly heat waves may increase by a factor of five to ten, with 150–750 million person-days of exposure to wet bulb temperatures above those seen in today’s most severe heat waves by 2070–2080. Under RCP 8.5, exposure to wet bulb temperatures above 35 °C—the theoretical limit for human tolerance—could exceed a million person-days per year by 2080. Limiting emissions to follow RCP 4.5 entirely eliminates exposure to that extreme threshold. Some of the most affected regions, especially Northeast India and coastal West Africa, currently have scarce cooling infrastructure, relatively low adaptive capacity, and rapidly growing populations. In the coming decades heat stress may prove to be one of the most widely experienced and directly dangerous aspects of climate change, posing a severe threat to human health, energy infrastructure, and outdoor activities ranging from agricultural production to military training.

  9. Nanosecond laser texturing of uniformly and non-uniformly wettable micro structured metal surfaces for enhanced boiling heat transfer

    Energy Technology Data Exchange (ETDEWEB)

    Zupančič, Matevž, E-mail: matevz.zupancic@fs.uni-lj.si; Može, Matic; Gregorčič, Peter; Golobič, Iztok

    2017-03-31

    Highlights: • Surfaces with periodically changed wettability were produced by a ns marking laser. • Heat transfer was investigated on uniformly and non-uniformly wettable surfaces. • Microporous surfaces with non-uniform wettability enhance boiling heat transfer. • The most bubble nucleations were observed in the vicinity of the microcavities. • Results agree with the predictions of the nucleation criteria. - Abstract: Microstructured uniformly and non-uniformly wettable surfaces were created on 25-μm-thin stainless steel foils by laser texturing using a marking nanosecond Nd:YAG laser (λ = 1064 nm) and utilizing various laser fluences and scan line separations. High-speed photography and high-speed IR thermography were used to investigate nucleate boiling heat transfer on the microstructured surfaces. The most pronounced results were obtained on a surface with non-uniform microstructure and non-uniform wettability. The obtained results show up to a 110% higher heat transfer coefficients and 20–40 times higher nucleation site densities compared to the untextured surface. We show that the number of active nucleation sites is significantly increased in the vicinity of microcavities that appeared in areas with the smallest (10 μm) scan line separation. Furthermore, this confirms the predictions of nucleation criteria and proves that straightforward, cost-effective nanosecond laser texturing allows the production of cavities with diameters of up to a few micrometers and surfaces with non-uniform wettability. Additionally, this opens up important possibilities for a more deterministic control over the complex boiling process.

  10. Effect of spatial nonuniformity of heating on compression and burning of a thermonuclear target under direct multibeam irradiation by a megajoule laser pulse

    Energy Technology Data Exchange (ETDEWEB)

    Bel’kov, S. A.; Bondarenko, S. V. [Russian Federal Nuclear Center, All-Russia Research Institute of Experimental Physics (Russian Federation); Vergunova, G. A. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation); Garanin, S. G. [Russian Federal Nuclear Center, All-Russia Research Institute of Experimental Physics (Russian Federation); Gus’kov, S. Yu.; Demchenko, N. N.; Doskoch, I. Ya. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation); Zmitrenko, N. V. [Russian Academy of Sciences, Keldysh Institute of Applied Mathematics (Russian Federation); Kuchugov, P. A., E-mail: pkuchugov@gmail.com; Rozanov, V. B.; Stepanov, R. V.; Yakhin, R. A. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)

    2017-02-15

    Direct-drive fusion targets are considered at present as an alternative to targets of indirect compression at a laser energy level of about 2 MJ. In this approach, the symmetry of compression and ignition of thermonuclear fuel play the major role. We report on the results of theoretical investigation of compression and burning of spherical direct-drive targets in the conditions of spatial nonuniformity of heating associated with a shift of the target from the beam center of focusing and possible laser radiation energy disbalance in the beams. The investigation involves numerous calculations based on a complex of 1D and 2D codes RAPID, SEND (for determining the target illumination and the dynamics of absorption), DIANA, and NUT (1D and multidimensional hydrodynamics of compression and burning of targets). The target under investigation had the form of a two-layer shell (ablator made of inertial material CH and DT ice) filled with DT gas. We have determined the range of admissible variation of compression and combustion parameters of the target depending on the variation of the spatial nonuniformity of its heating by a multibeam laser system. It has been shown that low-mode (long-wavelength) perturbations deteriorate the characteristics of the central region due to less effective conversion of the kinetic energy of the target shell into the internal energy of the center. Local initiation of burning is also observed in off-center regions of the target in the case of substantial asymmetry of irradiation. In this case, burning is not spread over the entire volume of the DT fuel as a rule, which considerably reduces the thermonuclear yield as compared to that in the case of spherical symmetry and central ignition.

  11. Research on the Grain Boundary Liquation Mechanism in Heat Affected Zones of Laser Forming Repaired K465 Nickel-Based Superalloy

    Directory of Open Access Journals (Sweden)

    Qiuge Li

    2016-03-01

    Full Text Available The damaged K465 nickel-based superalloy parts were repaired by laser forming repair technology. The cracking characteristics and grain boundary liquation in heat affected zones were investigated by optical microscopy (OM, scanning electron microscopy (SEM, and transmission electron microscopy (TEM. It was found that the cracks originated from the heat-affected zone and extended to the repaired zone. The calculation by Thermol-Cale software showed that the larger γ′ particles at grain boundaries partly dissolved in the γ phase, which made the solutes’ concentration at the γ′/γ interface meet the eutectic-type liquation reaction condition of γ + γ′ → L. Then, grain boundaries liquation occurred and liquid films appeared with the temperature increasing in a rapid heating process. However, the intragranular γ′ phase completely dissolved into the γ phase with no devotion to the liquid film. The dissolution of M5B3 borides at grain boundaries could promote grain boundary liquation.

  12. A molecular dynamics study on thin film liquid boiling characteristics under rapid linear boundary heating: Effect of liquid film thickness

    Science.gov (United States)

    Rabbi, Kazi Fazle; Tamim, Saiful Islam; Faisal, A. H. M.; Mukut, K. M.; Hasan, Mohammad Nasim

    2017-06-01

    This study is a molecular dynamics investigation of phase change phenomena i.e. boiling of thin liquid films subjected to rapid linear heating at the boundary. The purpose of this study is to understand the phase change heat transfer phenomena at nano scale level. In the simulation, a thin film of liquid argon over a platinum surface has been considered. The simulation domain herein is a three-phase system consisting of liquid and vapor argon atoms placed over a platinum wall. Initially the whole system is brought to an equilibrium state at 90 K and then the temperature of the bottom wall is increased to a higher temperature (250K) within a finite time interval. Four different liquid argon film thicknesses have been considered (3 nm, 4 nm, 5 nm and 6 nm) in this study. The boundary heating rate (40×109 K/s) is kept constant in all these cases. Variation in system temperature, pressure, net evaporation number, spatial number density of the argon region with time for different film thickness have been demonstrated and analyzed. The present study indicates that the pattern of phase transition may be significantly different (i.e. evaporation or explosive boiling) depending on the liquid film thickness. Among the four cases considered in the present study, explosive boiling has been observed only for the liquid films of 5nm and 6nm thickness, while for the other cases, evaporation take place.

  13. Rapid presumptive identification of the Mycobacterium tuberculosis-bovis complex by radiometric determination of heat stable urease

    Energy Technology Data Exchange (ETDEWEB)

    Gandy, J.H.; Pruden, E.L.; Cox, F.R.

    1983-12-01

    Simple and rapid Bactec methodologies for the determination of neat (unaltered) and heat stable urease activity of mycobacteria are presented. Clinical isolates (63) and stock cultures (32)--consisting of: M. tuberculosis (19), M. bovis (5), M. kansasii (15), M. marinum (4), M. simiae (3), M. scrofulaceum (16), M. gordonae (6), M. szulgai (6), M. flavescens (1), M. gastri (1), M. intracellulare (6), M. fortuitum-chelonei complex (12), and M. smegmatis (1)--were tested for neat urease activity by Bactec radiometry. Mycobacterial isolates (50-100 mg wet weight) were incubated at 35 degrees C for 30 minutes with microCi14C-urea. Urease-positive mycobacteria gave Bactec growth index (GI) values greater than 100 units, whereas urease-negative species gave values less than 10 GI units. Eighty-three isolates possessing neat urease activity were heated at 80 degrees C for 30 minutes followed by incubation at 35 degrees C for 30 minutes with 1 microCi14C-urea. Mycobacterium tuberculosis-bovis complex demonstrated heat-stable urease activity (GI more than 130 units) and could be distinguished from mycobacteria other than tuberculosis (MOTT), which gave GI values equal to or less than 40 units.

  14. Rapid identification of bacillus anthracis spores in suspicious powder samples by using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS)

    NARCIS (Netherlands)

    Dybwad, M.; Laaken, A.L. van der; Blatny, J.M.; Paauw, A.

    2013-01-01

    Rapid and reliable identification of Bacillus anthracis spores in suspicious powders is important to mitigate the safety risks and economic burdens associated with such incidents. The aim of this study was to develop and validate a rapid and reliable laboratory- based matrix-assisted laser

  15. Compact, rapid, and rugged detector of military and improvised explosives based on external grating cavity quantum cascade lasers

    Science.gov (United States)

    Tsekoun, Alexei; Dunayevskiy, Ilya; Maulini, Richard; Barron-Jimenez, Rodolfo; Lyakh, Arkadiy; Patel, C. Kumar N.

    2009-08-01

    Early detection of explosive substances is the first and most difficult step in defeating explosive devices. Many currently available methods suffer from fundamental failure modes limiting their realworld suitability. Infrared spectroscopy is ideal for reliable identification of explosives since it probes the chemical composition of molecules. Quantum cascade lasers rapidly became the light source of choice of IR spectroscopy due to their wavelength agility, relatively high output power, and small size and weight. Our compact, rapid, and rugged multi-explosives sensor based on external grating cavity QCLs simultaneously detects TNT, TATP, and acetone while being immune to ammonium nitrate interference. The instrument features low false alarm rate, and low probability of false negatives. Receiver operation characteristics curves are presented.

  16. Laser Chemosensor with Rapid Responsivity and Inherent Memory Based on a Polymer of Intrinsic Microporosity

    Directory of Open Access Journals (Sweden)

    Graham A. Turnbull

    2011-02-01

    Full Text Available This work explores the use of a polymer of intrinsic microporosity (PIM-1 as the active layer within a laser sensor to detect nitroaromatic-based explosive vapors. We show successful detection of dinitrobenzene (DNB by monitoring the real-time photoluminescence. We also show that PIM-1 has an inherent memory, so that it accumulates the analyte during exposure. In addition, the optical gain and refractive index of the polymer were studied by amplified spontaneous emission and variable-angle ellipsometry, respectively. A second-order distributed feedback PIM-1 laser sensor was fabricated and found to show an increase in laser threshold of 2.5 times and a reduction of the laser slope efficiency by 4.4 times after a 5-min exposure to the DNB vapor. For pumping at 2 times threshold, the lasing action was stopped within 30 s indicating that PIM-1 has a very fast responsivity and as such has a potential sensing ability for ultra-low-concentration explosives.

  17. Laser chemosensor with rapid responsivity and inherent memory based on a polymer of intrinsic microporosity.

    Science.gov (United States)

    Wang, Yue; McKeown, Neil B; Msayib, Kadhum J; Turnbull, Graham A; Samuel, Ifor D W

    2011-01-01

    This work explores the use of a polymer of intrinsic microporosity (PIM-1) as the active layer within a laser sensor to detect nitroaromatic-based explosive vapors. We show successful detection of dinitrobenzene (DNB) by monitoring the real-time photoluminescence. We also show that PIM-1 has an inherent memory, so that it accumulates the analyte during exposure. In addition, the optical gain and refractive index of the polymer were studied by amplified spontaneous emission and variable-angle ellipsometry, respectively. A second-order distributed feedback PIM-1 laser sensor was fabricated and found to show an increase in laser threshold of 2.5 times and a reduction of the laser slope efficiency by 4.4 times after a 5-min exposure to the DNB vapor. For pumping at 2 times threshold, the lasing action was stopped within 30 s indicating that PIM-1 has a very fast responsivity and as such has a potential sensing ability for ultra-low-concentration explosives.

  18. Heating of multi-layered samples by a Nd: YAG pulsed laser

    Directory of Open Access Journals (Sweden)

    Diniz Neto, O. O.

    1998-04-01

    Full Text Available In the work we examine the heating of multi-layered samples by a powerful Nd - YAG pulsed láser. The samples are made of two and three layers, conductor-isolator (Al-Al2O3, conductor-conductor (Al-Ag; Al-Au and conductor-conductor-conductor (Al-Au-Ag; Ag-Au-Al. The transient behaviour of the temperature distribution throughout the sample is computed. We carry out three dimensional model calculations for the heating process in which we consider not only the temperature dependence of the sample thermal and optical parameters but also the space and time characteristics of the laser beam as the heating source. We showed the influence of the substrate in the thermal profile, in space and time, and máximum temperature on the multi-layered samples.

    Em nosso trabalho examinamos o aquecimento de amostras compostas de duas e três camadas, condutor- isolante e condutor-condutor, com um pulso potente de láser. O comportamento transiente da distribuição de temperatura através da amostra foi calculado. Em nosso modelo de calculo para o processo de aquecimento levamos em conta a dependência com a temperatura dos parâmetros térmicos (difusividade, capacidade e condutividade térmica, óticos (refletividade e coeficiente de absorção, bem como a dependência das condições de contorno com o tempo e consequentemente com a temperatura. Aplicamos nossa metodología para calcular o aquecimento amostras compostas: Al-Au, Al-Ag, Al-Al2O3, Al-Au-Ag e Ag-Au-Al. Concluimos que o substrato influencia as temperaturas máximas nas superfície exposta ao láser e a forma com que a frente de calor se propaga nas amostras termicamente finas.

  19. Hafnium nitride films for thermoreflectance transducers at high temperatures: Potential based on heating from laser absorption

    Science.gov (United States)

    Rost, Christina M.; Braun, Jeffrey; Ferri, Kevin; Backman, Lavina; Giri, Ashutosh; Opila, Elizabeth J.; Maria, Jon-Paul; Hopkins, Patrick E.

    2017-10-01

    Time domain thermoreflectance (TDTR) and frequency domain thermoreflectance (FDTR) are common pump-probe techniques that are used to measure the thermal properties of materials. At elevated temperatures, transducers used in these techniques can become limited by melting or other phase transitions. In this work, time domain thermoreflectance is used to determine the viability of HfN thin film transducers grown on SiO2 through measurements of the SiO2 thermal conductivity up to approximately 1000 K. Further, the reliability of HfN as a transducer is determined by measuring the thermal conductivities of MgO, Al2O3, and diamond at room temperature. The thermoreflectance coefficient of HfN was found to be 1.4 × 10-4 K-1 at 800 nm, one of the highest thermoreflectance coefficients measured at this standard TDTR probe wavelength. Additionally, the high absorption of HfN at 400 nm is shown to enable reliable laser heating to elevate the sample temperature during a measurement, relative to other transducers.

  20. Heat Loss in a Laser-Driven, Magnetized, X-Ray Source with Thermoelectric Terms

    Science.gov (United States)

    Giuliani, J. L.; Velikovich, A. L.; Kemp, G. E.; Colvin, J. D.; Koning, J.; Fournier, K. B.

    2016-10-01

    The efficiency of laser-driven K-shell radiation sources, i.e., pipes containing a gas or a metal foam, may be improved by using an axial magnetic field to thermally insulate the pipe wall from the hot interior. A planar, self-similar solution for the magnetic and thermal diffusion is developed to model the near wall physics that includes the thermoelectric Nernst and Ettingshausen effects. This solution extends previous work for the MagLIF concept to include the full dependence of the transport coefficients on the electron Hall parameter. The analytic solution assumes a constant pressure. This case is matched with a 1D MHD code, which is then applied to the case allowing for pressure gradients. These numerical solutions are found to evolve toward the self-similar ones. The variation of the time integrated heat loss with and without the thermoelectric terms will be examined. The present work provides a verification test for general MHD codes that use Braginskii's or Epperlein-Haines' transport model to account for thermoelectric effects. NRL supported by the DOE/NNSA. LLNL work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.

  1. Characterization of 4H Silicon Carbide Films Grown by Solvent-Laser Heated Floating Zone

    Science.gov (United States)

    Woodworth, Andrew, A; Sayir, Ali; Neudeck, Philip, G; Raghothamachar, Balaji; Dudley, Michael

    2012-01-01

    Commercially available bulk silicon carbide (SiC) has a high number (>2000/sq cm) of screw dislocations (SD) that have been linked to degradation of high-field power device electrical performance properties. Researchers at the NASA Glenn Research Center have proposed a method to mass-produce significantly higher quality bulk SiC. In order for this bulk growth method to become reality, growth of long single crystal SiC fibers must first be achieved. Therefore, a new growth method, Solvent-Laser Heated Floating Zone (Solvent-LHFZ), has been implemented. While some of the initial Solvent-LHFZ results have recently been reported, this paper focuses on further characterization of grown crystals and their growth fronts. To this end, secondary ion mass spectroscopy (SIMS) depth profiles, cross section analysis by focused ion beam (FIB) milling and mechanical polishing, and orientation and structural characterization by x-ray transmission Laue diffraction patterns and x-ray topography were used. Results paint a picture of a chaotic growth front, with Fe incorporation dependant on C concentration.

  2. Mechanical Testing of PMCs under Simulated Rapid Heat-Up Propulsion Environments. II; In-Plane Compressive Behavior

    Science.gov (United States)

    Stokes, Eric H.; Shin, E. Eugene; Sutter, James K.

    2003-01-01

    Carbon fiber thermoset polymer matrix composites (PMC) with high temperature polyimide based in-situ polymerized monomer reactant (PMR) resin has been used for some time in applications which can see temperatures up to 550 F. Currently, graphite fiber PMR based composites are used in several aircraft engine components including the outer bypass duct for the GE F-404, exit flaps for the P&W F-100-229, and the core cowl for the GE/Snecma CF6-80A3. Newer formulations, including PMR-II-50 are being investigated as potential weight reduction replacements of various metallic components in next generation high performance propulsion rocket engines that can see temperatures which exceed 550 F. Extensive FEM thermal modeling indicates that these components are exposed to rapid heat-up rates (up to -200 F/sec) and to a maximum temperature of around 600 F. Even though the predicted maximum part temperatures were within the capability of PW-II-50, the rapid heat-up causes significant through-thickness thermal gradients in the composite part and even more unstable states when combined with moisture. Designing composite parts for such extreme service environments will require accurate measurement of intrinsic and transient mechanical properties and the hygrothermal performance of these materials under more realistic use conditions. The mechanical properties of polymers degrade when exposed to elevated temperatures even in the absence of gaseous oxygen. Accurate mechanical characterization of the material is necessary in order to reduce system weight while providing sufficient factors of safety. Historically, the testing of PMCs at elevated temperatures has been plagued by the antagonism between two factors. First, moisture has been shown to profoundly affect the mechanical response of these materials at temperatures above their glass transition temperature while concurrently lowering the material's Tg. Moisture phenomena is due to one or a combination of three effects, i

  3. Rapid automated materials synthesis instrument: exploring the composition and heat-treatment of nanoprecursors toward low temperature red phosphors.

    Science.gov (United States)

    Lin, Tian; Kellici, Suela; Gong, Kenan; Thompson, Kathryn; Evans, Julian R G; Wang, Xue; Darr, Jawwad A

    2010-05-10

    We report on the commissioning experimental run of the rapid automated materials synthesis instrument (RAMSI), a combinatorial robot designed to manufacture, clean, and print libraries of nanocrystal precursor solid compositions. The first stage of RAMSI, parallel synthesis, uses a fully automated high throughput continuous hydrothermal (HiTCH) flow reactor for automatic metal salt precursor mixing, hydrothermal flow reaction, and sample slurry collection. The second stage of RAMSI provides integrated automated cleanup, and the third section is a ceramic printing function. Nanocrystal precursor solid ceramics were synthesized from precursor solutions and collected into 50 mL centrifuge tubes where they were cleaned by multiple centrifugation and redispersion cycles (monitored by intelligent scanning turbidimetry) and printed with an automated pipette. Eight unique compositions of a model phosphor library comprising pure nano-Y(OH)(3) and Eu(3+) doped-yttrium hydroxide, Y(OH)(3):Eu(3+) nanocrystal precursor solid were synthesized (with 2 centrifuge tubes' worth collected per composition), processed, and printed in duplicate as 75, 100, and 125 microL dots in a 21.6 ks (6 h) experiment (note: the actual time for synthesis of each sample tube was only 12 min so up to 60 compositions could easily be synthesized in 12 h if one centrifuge tube per composition was collected instead). The Y(OH)(3):Eu(3+) samples were manually placed in a furnace and heat-treated in air for 14.4 ks (4 h) in the temperature range 200-1200 at 100 degrees C intervals (giving a total of 84 samples plus one as-prepared pure Y(OH)(3) sample). The as-prepared and heat-treated ceramic samples were affixed to 4 mm wide hemispherical wells in a custom-made aluminum well-plate and analyzed using a fluorescence spectrometer. When the library was illuminated with a 254 nm light source (and digitally imaged and analyzed), the 3 mol % Eu(3+) sample heat-treated at 1200 degrees C gave the most intense

  4. Comparison of heat induced damage at the saphenofemoral junction after ablation with 1,470 nm laser or radiofrequency.

    Science.gov (United States)

    Ozcinar, Evren; Cakici, Mehmet; Korun, Oktay; Han, Unsal; Kiziltepe, Ugursay

    2017-03-01

    The aim of this study was to evaluate the heat induced damage at the saphenofemoral junction level according to histopathological changes after radiofrequency or 1,470 nm radial tip laser ablation. Varicose vein segments of 6-10 mm in diameter were exposed to radiofrequency (Closure Fast catheter, 7 cm heat segment, one cycle, 15 seconds, 10 Watt, 120 °C) or laser ablation (1,470 nm radial tip, continuous wave, vein diameter: 6 cm/8 cm/10 cm-power: 10 Watt-pullback speed: 2.2 mm/s, 1.7 mm/s, 1.3 mm/s-LEED: 45J/cm, 60J/cm, 75J/cm-EFE 25J/cm(2), respectively). Approximate 2 cm segments of the vein were left untreated, then histopathological examinations of the untouched segments (5 slices: level 1 - furthest segment, level 2 - nearest segment) for heat induced damage were performed. A total damage scoring system was established, including the presence of endothelial swelling, intimal thickening, cellular vacuolisation in the muscle layer, oedema in the tunica media, and extent of necrosis. At level 1, the furthest segment of the specimen, there was no significant difference between the laser and control group, while the total damage score of the radiofrequency group was significantly higher than the control group (p laser group at level 1 (p ablation seems to cause more histological damage than laser ablation in this ex vivo study. Further in vivo studies are necessary, in order to validate these findings.

  5. Laser Measurement of the Speed of Sound in Gases: A Novel Approach to Determining Heat Capacity Ratios and Gas Composition

    Science.gov (United States)

    Baum, J. Clayton; Compton, R. N.; Feigerle, Charles S.

    2008-01-01

    The speed of sound is measured in several gases using a pulsed laser to create a micro-spark on a carbon rod and a microphone connected to a digital oscilloscope to measure the time-of-flight of the resulting shockwave over a known distance. These data are used to calculate the heat capacity ratios (C[subscript p]/C[subscript V]) of the gases and…

  6. Static diode pumped alkali lasers: Model calculations of the effects of heating, ionization, high electronic excitation and chemical reactions

    Science.gov (United States)

    Barmashenko, B. D.; Rosenwaks, S.; Heaven, M. C.

    2013-04-01

    The effects of heating, ionization, high electronic excitation and chemical reactions on the operation of diode pumped alkali lasers (DPALs) with a static, non-flowing gain medium are calculated using a semi-analytical model. Unlike other models, assuming a three-level scheme of the laser and neglecting influence of the temperature on the lasing power, it takes into account the temperature rise and losses of neutral alkali atoms due to ionization and chemical reactions, resulting in decrease of the pump absorption and slope efficiency. Good agreement with measurements in a static DPAL [B.V. Zhdanov, J. Sell, R.J. Knize, Electron. Lett. 44 (2008) 582] is obtained. It is found that the ionization processes have a small effect on the laser operation, whereas the chemical reactions of alkali atoms with hydrocarbons strongly affect the lasing power.

  7. Time-resolved temperature measurements in a rapid compression machine using quantum cascade laser absorption in the intrapulse mode

    KAUST Repository

    Nasir, Ehson Fawad

    2016-07-16

    A temperature sensor based on the intrapulse absorption spectroscopy technique has been developed to measure in situ temperature time-histories in a rapid compression machine (RCM). Two quantum-cascade lasers (QCLs) emitting near 4.55μm and 4.89μm were operated in pulsed mode, causing a frequency "down-chirp" across two ro-vibrational transitions of carbon monoxide. The down-chirp phenomenon resulted in large spectral tuning (δν ∼2.8cm-1) within a single pulse of each laser at a high pulse repetition frequency (100kHz). The wide tuning range allowed the application of the two-line thermometry technique, thus making the sensor quantitative and calibration-free. The sensor was first tested in non-reactive CO-N2 gas mixtures in the RCM and then applied to cases of n-pentane oxidation. Experiments were carried out for end of compression (EOC) pressures and temperatures ranging 9.21-15.32bar and 745-827K, respectively. Measured EOC temperatures agreed with isentropic calculations within 5%. Temperature rise measured during the first-stage ignition of n-pentane is over-predicted by zero-dimensional kinetic simulations. This work presents, for the first time, highly time-resolved temperature measurements in reactive and non-reactive rapid compression machine experiments. © 2016 Elsevier Ltd.

  8. Laser Induced breakdown spectroscopy: A rapid tool for the identification and quantification of minerals in cucurbit seeds.

    Science.gov (United States)

    Singh, Jyotsana; Kumar, Rohit; Awasthi, Shikha; Singh, Vinti; Rai, A K

    2017-04-15

    Laser-induced breakdown spectroscopy (LIBS) was investigated to estimate the viability as a simple and rapid method for analysis of nutrient elements in seed kernels of cucurbits. LIBS spectra were recorded in the range of 200-975nm by using Q-switched Nd:YAG laser at 532nm (4ns, 10Hz) attached to echelle spectrometer with intensified charged coupled device (ICCD). The spectral analysis revealed the presence of several elements like C, O, N, Mg, Ca, Na and K in seeds. The quantification of elements (Mg, Ca, Na and K) through LIBS was done using calibration curve method in which all calibration curve shows good linearity (r>0.95). The result obtained through LIBS was in reasonable agreement with that obtained through atomic absorption spectroscopy (AAS). Principal Component Analysis (PCA) was also applied to the LIBS data for rapid categorization of seed samples belonging to same species although samples have similar nutrient elements. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Transient, three-dimensional heat transfer model for the laser assisted machining of silicon nitride: 1. Comparison of predictions with measured surface temperature histories

    Energy Technology Data Exchange (ETDEWEB)

    Rozzi, J.C.; Pfefferkorn, F.E.; Shin, Y.C. [Purdue University, (United States). Laser Assisted Materials Processing Laboratory, School of Mechanical Engineering; Incropera, F.P. [University of Notre Dame, (United States). Aerospace and Mechanical Engineering Department

    2000-04-01

    Laser assisted machining (LAM), in which the material is locally heated by an intense laser source prior to material removal, provides an alternative machining process with the potential to yield higher material removal rates, as well as improved control of workpiece properties and geometry, for difficult-to-machine materials such as structural ceramics. To assess the feasibility of the LAM process and to obtain an improved understanding of governing physical phenomena, experiments have been performed to determine the thermal response of a rotating silicon nitride workpiece undergoing heating by a translating CO{sub 2} laser and material removal by a cutting tool. Using a focused laser pyrometer, surface temperature histories were measured to determine the effect of the rotational and translational speeds, the depth of cut, the laser-tool lead distance, and the laser beam diameter and power on thermal conditions. The measurements are in excellent agreement with predictions based on a transient, three-dimensional numerical solution of the heating and material removal processes. The temperature distribution within the unmachined workpiece is most strongly influenced by the laser power and laser-tool lead distance, as well as by the laser/tool translational velocity. A minimum allowable operating temperature in the material removal region corresponds to the YSiAlON glass transition temperature, below which tool fracture may occur. In a companion paper, the numerical model is used to further elucidate thermal conditions associated with laser assisted machining. (author)

  10. Selective Laser Melting Produced Ti-6Al-4V: Post-Process Heat Treatments to Achieve Superior Tensile Properties

    Directory of Open Access Journals (Sweden)

    Gerrit M. Ter Haar

    2018-01-01

    Full Text Available Current post-process heat treatments applied to selective laser melting produced Ti-6Al-4V do not achieve the same microstructure and therefore superior tensile behaviour of thermomechanical processed wrought Ti-6Al-4V. Due to the growing demand for selective laser melting produced parts in industry, research and development towards improved mechanical properties is ongoing. This study is aimed at developing post-process annealing strategies to improve tensile behaviour of selective laser melting produced Ti-6Al-4V parts. Optical and electron microscopy was used to study α grain morphology as a function of annealing temperature, hold time and cooling rate. Quasi-static uniaxial tensile tests were used to measure tensile behaviour of different annealed parts. It was found that elongated α’/α grains can be fragmented into equiaxial grains through applying a high temperature annealing strategy. It is shown that bi-modal microstructures achieve a superior tensile ductility to current heat treated selective laser melting produced Ti-6Al-4V samples.

  11. Assessment of the efficacy of laser hyperthermia and nanoparticle-enhanced therapies by heat shock protein analysis

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Fei [Department of Precision Instrument, Tsinghua University, Beijing, 100084 (China); Zhang, Ye; Zhang, Juan; Liu, Ran, E-mail: liuran@tsinghua.edu.cn [Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, 100084 (China); Guo, Junwei [Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing, 100084 (China)

    2014-03-15

    Tumor thermotherapy is a method of cancer treatment wherein cancer cells are killed by exposing the body tissues to high temperatures. Successful clinical implementation of this method requires a clear understanding and assessment of the changes of the tumor area after the therapy. In this study, we evaluated the effect of near-infrared laser tumor thermotherapy at the molecular, cellular, and physical levels. We used single-walled carbon nanotubes (SWNTs) in combination with this thermotherapy. We established a mouse model for breast cancer and randomly divided the mice into four groups: mice with SWNT-assisted thermotherapy; mice heat treated without SWNT; mice injected with SWNTs without thermotherapy; and a control group. Tumors were irradiated using a near-infrared laser with their surface temperature remaining at approximately 45 °C. We monitored the tumor body growth trend closely by daily physical measurements, immunohistochemical staining, and H and E (hematoxylin-eosin) staining by stage. Our results showed that infrared laser hyperthermia had a significant inhibitory effect on the transplanted breast tumor, with an inhibition rate of 53.09%, and also significantly reduced the expression of the heat shock protein Hsp70. Furthermore, we have found that protein analysis and histological analysis can be used to assess therapeutic effects effectively, presenting broad application prospects for determining the effect of different treatments on tumors. Finally, we discuss the effects of SWNT-assisted near-infrared laser tumor thermotherapy on tumor growth at the molecular, cellular, and physical levels.

  12. Assessment of the efficacy of laser hyperthermia and nanoparticle-enhanced therapies by heat shock protein analysis

    Science.gov (United States)

    Tang, Fei; Zhang, Ye; Zhang, Juan; Guo, Junwei; Liu, Ran

    2014-03-01

    Tumor thermotherapy is a method of cancer treatment wherein cancer cells are killed by exposing the body tissues to high temperatures. Successful clinical implementation of this method requires a clear understanding and assessment of the changes of the tumor area after the therapy. In this study, we evaluated the effect of near-infrared laser tumor thermotherapy at the molecular, cellular, and physical levels. We used single-walled carbon nanotubes (SWNTs) in combination with this thermotherapy. We established a mouse model for breast cancer and randomly divided the mice into four groups: mice with SWNT-assisted thermotherapy; mice heat treated without SWNT; mice injected with SWNTs without thermotherapy; and a control group. Tumors were irradiated using a near-infrared laser with their surface temperature remaining at approximately 45 °C. We monitored the tumor body growth trend closely by daily physical measurements, immunohistochemical staining, and H&E (hematoxylin-eosin) staining by stage. Our results showed that infrared laser hyperthermia had a significant inhibitory effect on the transplanted breast tumor, with an inhibition rate of 53.09%, and also significantly reduced the expression of the heat shock protein Hsp70. Furthermore, we have found that protein analysis and histological analysis can be used to assess therapeutic effects effectively, presenting broad application prospects for determining the effect of different treatments on tumors. Finally, we discuss the effects of SWNT-assisted near-infrared laser tumor thermotherapy on tumor growth at the molecular, cellular, and physical levels.

  13. Assessment of the efficacy of laser hyperthermia and nanoparticle-enhanced therapies by heat shock protein analysis

    Directory of Open Access Journals (Sweden)

    Fei Tang

    2014-03-01

    Full Text Available Tumor thermotherapy is a method of cancer treatment wherein cancer cells are killed by exposing the body tissues to high temperatures. Successful clinical implementation of this method requires a clear understanding and assessment of the changes of the tumor area after the therapy. In this study, we evaluated the effect of near-infrared laser tumor thermotherapy at the molecular, cellular, and physical levels. We used single-walled carbon nanotubes (SWNTs in combination with this thermotherapy. We established a mouse model for breast cancer and randomly divided the mice into four groups: mice with SWNT-assisted thermotherapy; mice heat treated without SWNT; mice injected with SWNTs without thermotherapy; and a control group. Tumors were irradiated using a near-infrared laser with their surface temperature remaining at approximately 45 °C. We monitored the tumor body growth trend closely by daily physical measurements, immunohistochemical staining, and H&E (hematoxylin-eosin staining by stage. Our results showed that infrared laser hyperthermia had a significant inhibitory effect on the transplanted breast tumor, with an inhibition rate of 53.09%, and also significantly reduced the expression of the heat shock protein Hsp70. Furthermore, we have found that protein analysis and histological analysis can be used to assess therapeutic effects effectively, presenting broad application prospects for determining the effect of different treatments on tumors. Finally, we discuss the effects of SWNT-assisted near-infrared laser tumor thermotherapy on tumor growth at the molecular, cellular, and physical levels.

  14. Effect of Heat Treatment on Liquation Cracking in Continuous Fiber and Pulsed Nd:YAG Laser Welding of HASTELLOY X Alloy

    Science.gov (United States)

    Pakniat, M.; Ghaini, F. Malek; Torkamany, M. J.

    2017-11-01

    Laser welding of HASTELLOY X is highly feasible; however, hot cracking can be a matter of concern. The objective of this study is to assess the effect of solution heat treatment on susceptibility to liquation cracking in welding of a 2-mm-thick HASTELLOY X plate. In addition, Nd-YAG pulsed laser (400 W) and continuous wave (CW) fiber laser (600 W) were compared with each other in this respect. Results revealed that performing the prewelding solution heat treatment reduces the tendency for occurrence of liquation cracking. Furthermore, it was established that by increasing pulse frequency, there was a significant reduction in the tendency for liquation cracking. With CW laser welding of HASTELLOY X in the solution-heat-treated condition, the tendency for heat-affected zone (HAZ) cracking was found to be minimized.

  15. Combined resistive and laser heating technique for in situ radial X-ray diffraction in the diamond anvil cell at high pressure and temperature

    Energy Technology Data Exchange (ETDEWEB)

    Miyagi, Lowell [Department of Geology and Geophysics, University of Utah, Salt Lake City, Utah 84112 (United States); Department of Earth Sciences, Montana State University, Bozeman, Montana 59717 (United States); Kanitpanyacharoen, Waruntorn; Kaercher, Pamela; Wenk, Hans-Rudolf; Alarcon, Eloisa Zepeda [Department of Earth and Planetary Science, University of California, Berkeley, California 94720 (United States); Raju, Selva Vennila [Advanced Light Source, Lawrence Berkeley Laboratory, Berkeley, California 94720 (United States); HiPSEC, Department of Physics, University of Nevada, Las Vegas, Nevada 89154 (United States); Knight, Jason; MacDowell, Alastair [Advanced Light Source, Lawrence Berkeley Laboratory, Berkeley, California 94720 (United States); Williams, Quentin [Department of Earth and Planetary Science, University of California, Santa Cruz, California 95064 (United States)

    2013-02-15

    To extend the range of high-temperature, high-pressure studies within the diamond anvil cell, a Liermann-type diamond anvil cell with radial diffraction geometry (rDAC) was redesigned and developed for synchrotron X-ray diffraction experiments at beamline 12.2.2 of the Advanced Light Source. The rDAC, equipped with graphite heating arrays, allows simultaneous resistive and laser heating while the material is subjected to high pressure. The goals are both to extend the temperature range of external (resistive) heating and to produce environments with lower temperature gradients in a simultaneously resistive- and laser-heated rDAC. Three different geomaterials were used as pilot samples to calibrate and optimize conditions for combined resistive and laser heating. For example, in Run1, FeO was loaded in a boron-mica gasket and compressed to 11 GPa then gradually resistively heated to 1007 K (1073 K at the diamond side). The laser heating was further applied to FeO to raise temperature to 2273 K. In Run2, Fe-Ni alloy was compressed to 18 GPa and resistively heated to 1785 K (1973 K at the diamond side). The combined resistive and laser heating was successfully performed again on (Mg{sub 0.9}Fe{sub 0.1})O in Run3. In this instance, the sample was loaded in a boron-kapton gasket, compressed to 29 GPa, resistive-heated up to 1007 K (1073 K at the diamond side), and further simultaneously laser-heated to achieve a temperature in excess of 2273 K at the sample position. Diffraction patterns obtained from the experiments were deconvoluted using the Rietveld method and quantified for lattice preferred orientation of each material under extreme conditions and during phase transformation.

  16. Combined resistive and laser heating technique for in situ radial X-ray diffraction in the diamond anvil cell at high pressure and temperature.

    Science.gov (United States)

    Miyagi, Lowell; Kanitpanyacharoen, Waruntorn; Raju, Selva Vennila; Kaercher, Pamela; Knight, Jason; MacDowell, Alastair; Wenk, Hans-Rudolf; Williams, Quentin; Alarcon, Eloisa Zepeda

    2013-02-01

    To extend the range of high-temperature, high-pressure studies within the diamond anvil cell, a Liermann-type diamond anvil cell with radial diffraction geometry (rDAC) was redesigned and developed for synchrotron X-ray diffraction experiments at beamline 12.2.2 of the Advanced Light Source. The rDAC, equipped with graphite heating arrays, allows simultaneous resistive and laser heating while the material is subjected to high pressure. The goals are both to extend the temperature range of external (resistive) heating and to produce environments with lower temperature gradients in a simultaneously resistive- and laser-heated rDAC. Three different geomaterials were used as pilot samples to calibrate and optimize conditions for combined resistive and laser heating. For example, in Run#1, FeO was loaded in a boron-mica gasket and compressed to 11 GPa then gradually resistively heated to 1007 K (1073 K at the diamond side). The laser heating was further applied to FeO to raise temperature to 2273 K. In Run#2, Fe-Ni alloy was compressed to 18 GPa and resistively heated to 1785 K (1973 K at the diamond side). The combined resistive and laser heating was successfully performed again on (Mg0.9Fe0.1)O in Run#3. In this instance, the sample was loaded in a boron-kapton gasket, compressed to 29 GPa, resistive-heated up to 1007 K (1073 K at the diamond side), and further simultaneously laser-heated to achieve a temperature in excess of 2273 K at the sample position. Diffraction patterns obtained from the experiments were deconvoluted using the Rietveld method and quantified for lattice preferred orientation of each material under extreme conditions and during phase transformation.

  17. High-speed scanning ablation of dental hard tissues with a λ = 9.3 μm CO2 laser: adhesion, mechanical strength, heat accumulation, and peripheral thermal damage

    Science.gov (United States)

    Nguyen, Daniel; Chang, Kwang; Hedayatollahnajafi, Saba; Staninec, Michal; Chan, Kenneth; Lee, Robert; Fried, Daniel

    2011-07-01

    CO2 lasers can be operated at high laser pulse repetition rates for the rapid and precise removal of dental decay. Excessive heat accumulation and peripheral thermal damage is a concern when using high pulse repetition rates. Peripheral thermal damage can adversely impact the mechanical strength of the irradiated tissue, particularly for dentin, and reduce the adhesion characteristics of the modified surfaces. The interpulpal temperature rise was recorded using microthermocouples situated at the roof of the pulp chamber on teeth that were occlusally ablated using a rapidly-scanned CO2 laser operating at 9.3 μm with a pulse duration of 10 to 15 μs and repetition rate of 300 Hz over a 2 min time course. The adhesion strength of laser treated enamel and dentin surfaces was measured for various laser scanning parameters with and without post-ablation acid etching using the single-plane shear test. The mechanical strength of laser-ablated dentin surfaces were determined via the four-point bend test and compared to control samples prepared with 320 grit wet sand paper to simulate conventional preparations. Thermocouple measurements indicated that the temperature remained below ambient temperature if water-cooling was used. There was no discoloration of either dentin or enamel laser treated surfaces, the surfaces were uniformly ablated, and there were no cracks visible. Four-point bend tests yielded mean mechanical strengths of 18.2 N (s.d. = 4.6) for ablated dentin and 18.1 N (s.d. = 2.7) for control (p > 0.05). Shear tests yielded mean bond strengths approaching 30 MPa for both enamel and dentin under certain irradiation conditions. These values were slightly lower than nonirradiated acid-etched control samples. Additional studies are needed to determine if the slightly lower bond strength than the acid-etched control samples is clinically significant. These measurements demonstrate that enamel and dentin surfaces can be rapidly ablated by CO2 lasers with minimal

  18. Rapid manufacturing of polyethylene parts with controlled pore size gradients using selective laser sintering

    Directory of Open Access Journals (Sweden)

    Gean Vitor Salmoria

    2007-06-01

    Full Text Available In this study HDPE specimens were fabricated by selective laser sintering using different particle sizes to obtain controlled variations in the porosity. Electron microscopy, density measurements and mechanical analyses were conducted for the characterization of the specimens. Parts with controlled pore gradients were also manufactured and characterized. The specimens with larger particle sizes had a high sintering degree and a significant level of close pores, as shown by microscopy and density analyses. However, the mechanical properties of specimens prepared with large particles had low values due to the limited density of union points, i.e., low neck number/area. HDPE parts with pore gradients were prepared by selective laser sintering demonstrating that this technique can be used to easily control the structure and the properties of the parts manufactured. This technology may have applications in areas such as drug delivery devices and scaffolds for tissue engineering.

  19. Weldability with Process Parameters During Fiber Laser Welding of a Titanium Plate (II) - The Effect of Control of Heat Input on Weldability -

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jong Do; Kim, Ji Sung [Korea Maritime and Ocean Univ., Busan (Korea, Republic of)

    2016-12-15

    Laser welding is a high-density energy welding method. Hence, deep penetration and high welding speed can be realized with lower heat input as compared with conventional welding. The heat input of a CW laser welding is determined by laser power and welding speed. In this study, bead and lap welding of 0.5 mmt pure titanium was performed using a fiber laser. Its weldability with laser power and welding speed was evaluated. Penetration, bead width, joining length, and bead shape were investigated, and the mechanical properties were examined through tensile-shear strength tests. Welds with sound joining length were obtained when the laser power and welding speed were respectively 0.5 kW and 2.5 m/min, and 1.5 kW and 6 m/min, and the weld obtained at low output presented better ductility than that obtained at high output.

  20. Laser Chemosensor with Rapid Responsivity and Inherent Memory Based on a Polymer of Intrinsic Microporosity

    OpenAIRE

    Wang, Yue; McKeown, Neil B.; Msayib, Kadhum J.; Turnbull, Graham A.; Samuel, Ifor D. W.

    2011-01-01

    This work explores the use of a polymer of intrinsic microporosity (PIM-1) as the active layer within a laser sensor to detect nitroaromatic-based explosive vapors. We show successful detection of dinitrobenzene (DNB) by monitoring the real-time photoluminescence. We also show that PIM-1 has an inherent memory, so that it accumulates the analyte during exposure. In addition, the optical gain and refractive index of the polymer were studied by amplified spontaneous emission and variable-angle ...

  1. Rapid ablation of dental hard tissue using promoter-assisted pulsed Nd:YAG laser

    Science.gov (United States)

    Frederickson, Christopher J.; Lu, Quiang; Hayes, Donald J.; Wallace, David B.; Grove, Michael E.; Bell, Brent A.; Motamedi, Massoud; Rastegar, Sohi; Wright, C. G.; Arcoria, Charles J.

    1997-05-01

    Nd:YAG lasers have been used previously for selective removal of various material from teeth. To permit ablation of healthy enamel with the Nd:YAG laser, we have adopted a strategy in which micro-drops of photoabsorptive 'promoters' are placed on the enamel to enhance absorption of individual laser pulses. Ink-jet technology dispenses the micro-drops with micron- and millisecond-scale precision. Various promoters using drug and cosmetic dyes, indocyanine green, or carbon-black pigments have been studied. Typical ablation parameters are 1.064 micrometers ; 20-180 mJ per pulse; 100 microsecond(s) ; 10-30 pulses/sec; 0.2-2.0 nl drops. Recent results from the program include: (1) For a variety of promoters, a monotonic relationship obtains between absorption coefficient at 1.064 micrometers and the efficiency of ablation of enamel. (2) With different promoter volumes, the efficiency of ablation rises, plateaus, then falls with increasing volume. (3) At drilling rates of 30 pulses/sec, ablation efficiency approaches rates of 0.1 mm3/sec. LM and SEM observations show a glassy 'pebbled' crater surface indicative of hydroxyapatite that has cooled, condensed, and solidified on the crater walls. Together these results favor the view that a micro-drop promoter-assisted Nd:YAG drill can five clinically useful ablations hard dental tissue.

  2. Facilitation of a nociceptive flexion reflex in man by nonnoxious radiant heat produced by a laser.

    Science.gov (United States)

    Plaghki, L; Bragard, D; Le Bars, D; Willer, J C; Godfraind, J M

    1998-05-01

    Electromyographic recordings were made in healthy volunteers from the knee-flexor biceps femoris muscle of the nociceptive RIII reflex elicited by electrical stimulation of the cutaneous sural nerve. The stimulus intensity was adjusted to produce a moderate pricking-pain sensation. The test responses were conditioned by a nonnoxious thermal (CO2 laser stimulator and consisted of a 100-ms pulse of heat with a beam diameter of 20 mm. Its power was 22.7 +/- 4.2 W (7.2 mJ/mm2), and it produced a sensation of warmth. The maximum surface temperature reached at the end of the period of stimulation was calculated to be 7 degrees C above the actual reference temperature of the skin (32 degrees C). The interval between the laser (conditioning) and electrical (test) stimuli was varied from 50 to 3, 000 ms in steps of 50 ms. It was found that the nociceptive flexion reflex was facilitated by the thermal stimulus; this modulation occurred with particular conditioning-test intervals, which peaked at 500 and 1,100 ms with an additional late, long-lasting phase between 1,600 and 2,300 ms. It was calculated that the conduction velocities of the cutaneous afferent fibers responsible for facilitating the RIII reflex, fell into three ranges: one corresponding to A delta fibers (3.2 m/s) and two in the C fiber range (1.3 and 0.7 m/s). It is concluded that information emanating from warm receptors and nociceptors converges. In this respect, the present data show, for the first time, that in man, conditioning nonnociceptive warm thermoreceptive A delta and C fibers results in an interaction at the spinal level with a nociceptive reflex. This interaction may constitute a useful means whereby signals add together to trigger flexion reflexes in defensive reactions and other basic motor behaviors. It also may contribute to hyperalgesia in inflammatory processes. The methodology used in this study appears to be a useful noninvasive tool for exploring the thermoalgesic mechanisms in both

  3. The effect of particle size on the heat affected zone during laser cladding of Ni-Cr-Si-B alloy on C45 carbon steel

    Science.gov (United States)

    Tanigawa, Daichi; Abe, Nobuyuki; Tsukamoto, Masahiro; Hayashi, Yoshihiko; Yamazaki, Hiroyuki; Tatsumi, Yoshihiro; Yoneyama, Mikio

    2018-02-01

    Laser cladding is one of the most useful surface coating methods for improving the wear and corrosion resistance of material surfaces. Although the heat input associated with laser cladding is small, a heat affected zone (HAZ) is still generated within the substrate because this is a thermal process. In order to reduce the area of the HAZ, the heat input must therefore be reduced. In the present study, we examined the effects of the powdered raw material particle size on the heat input and the extent of the HAZ during powder bed laser cladding. Ni-Cr-Si-B alloy layers were produced on C45 carbon steel substrates in conjunction with alloy powders having average particle sizes of 30, 40 and 55 μm, while measuring the HAZ area by optical microscopy. The heat input required for layer formation was found to decrease as smaller particles were used, such that the HAZ area was also reduced.

  4. Monitoring Delamination of Thermal Barrier Coating During Interrupted High-Heat Flux Laser Testing Using Upconversion Luminescence Imaging

    Science.gov (United States)

    Eldridge, Jeffrey I.; Zhu, Dongming; Wolfe, Douglas E.

    2011-01-01

    Upconversion luminescence imaging of thermal barrier coatings (TBCs) has been shown to successfully monitor TBC delamination progression during interrupted furnace cycling. However, furnace cycling does not adequately model engine conditions where TBC-coated components are subjected to significant heat fluxes that produce through-thickness temperature gradients that may alter both the rate and path of delamination progression. Therefore, new measurements are presented based on luminescence imaging of TBC-coated specimens subjected to interrupted high-heat-flux laser cycling exposures that much better simulate the thermal gradients present in engine conditions. The TBCs tested were deposited by electron-beam physical vapor deposition (EB-PVD) and were composed of 7wt% yttria-stabilized zirconia (7YSZ) with an integrated delamination sensing layer composed of 7YSZ co-doped with erbium and ytterbium (7YSZ:Er,Yb). The high-heat-flux exposures that produce the desired through-thickness thermal gradients were performed using a high power CO2 laser operating at a wavelength of 10.6 microns. Upconversion luminescence images revealed the debond progression produced by the cyclic high-heat-flux exposures and these results were compared to that observed for furnace cycling.

  5. Integration of Heat Treatment with Shot Peening of 17-4 Stainless Steel Fabricated by Direct Metal Laser Sintering

    Science.gov (United States)

    AlMangour, Bandar; Yang, Jenn-Ming

    2017-11-01

    Direct metal laser sintering (DMLS) is a promising powder-based additive manufacturing process for fabrication of near-net-shape parts. However, the typically poor fatigue performance of DMLS parts must be addressed for use in demanding industrial applications. Post-treatment can be applied to enhance the performance of such components. Earlier attempts at inducing grain refinement through severe plastic deformation of part surfaces using shot peening improved the physical and mechanical properties of metals without chemical alteration. However, heat treatment can modify the surface-hardening effects attained by shot peening. Hence, we examined the feasibility of applying shot peening combined with heat treatment to improve the performance of DMLS-fabricated 17-4 stainless steel parts through microstructural evolution studies and hardness measurements. Compared to a specimen treated only by shot peening, the sample exposed to additional heat treatment showed increased hardness due to aging of the dominant phase.

  6. Effect of laser power and heat treatment process on microstructure and property of multi-pass Ni based alloy laser cladding coating

    Science.gov (United States)

    Wang, Chuanqi; Liu, Hongxi; Zhang, Xiaowei; Zeng, Weihua; Jiang, Yehua; Zhou, Rong

    2010-11-01

    Ni60CuMoW alloy power was clad on 45 steel surfaces using a synchronization powder feeding method by 6kW transverse-flow CO2 laser apparatus. The effect of laser power and heat treatment process on corrosion resistance of the cladding layer was investigated. The microstructure and mechanical property were analyzed by X-ray diffractometer (XRD), scanning electron microscope (SEM), energy depressive X-ray spectroscopy (EDX), microhardness meter and PS-268A electrochemical test equipment. The results show that the cladding layer is mainly composed of γ (Ni, Fe), solid solution (Ni, Cu), compounds Ni31Si12, Cr5B3, CrB, Ni3B, FeNi3, M23C6 (Cr23C6 or (Fe,Ni) 23C6) phase and a small amount of WC or W2C. With the increase of laser power, corrosion resistance and microhardness has been greatly improved. Compared with the untreated substrate, the maximum self-corrosion potential of single-pass layer at laser power 3.2 kW in 3.5% NaCl saturated solution increases by 136.2mV, and the lowest corrosion current density decreases by 2 orders of magnitude. The mean microhardness of treated samples raises by 5.17, 4.90 and 4.89 times, respectively. The corrosion potential of multi-pass layer increases by 437.6mV and corrosion current density decreases by one order of magnitude than that of single-pass layer sample. After temper 600°C heat treatment, the primary dendrite and block (or needle) eutectic in cladding coatings become more uniform, the maximum self-corrosion potential increases by 45.5mV and corrosion current density also decreases obviously.

  7. Sublethal Photothermal Stimulation with a Micropulse Laser Induces Heat Shock Protein Expression in ARPE-19 Cells

    Directory of Open Access Journals (Sweden)

    Keiji Inagaki

    2015-01-01

    Full Text Available Purpose/Aim of the Study. Subthreshold micropulse diode laser photocoagulation is an effective treatment for macular edema. The molecular mechanisms underlying treatment success are poorly understood. Therefore, we investigated the effects of sublethal laser energy doses on a single layer of densely cultured ARPE-19 cells as a model of the human retinal pigment epithelium (RPE. Materials and Methods. A single layer of densely cultured human ARPE-19 cells was perpendicularly irradiated with a micropulse diode laser. Nonirradiated cells served as controls. Sublethal laser energy was applied to form a photocoagulation-like area in the cultured cell layers. Hsp70 expression was evaluated using quantitative polymerase chain reaction and immunocytochemistry. Results. Photocoagulation-like areas were successfully created in cultured ARPE-19 cell layers using sublethal laser energy with our laser irradiation system. Hsp70 mRNA expression in cell layers was induced within 30 min of laser irradiation, peaking at 3 h after irradiation. This increase was dependent on the number of laser pulses. Hsp70 upregulation was not observed in untreated cell layers. Immunostaining indicated that Hsp70 expression occurred concentrically around laser irradiation sites and persisted for 24 h following irradiation. Conclusion. Sublethal photothermal stimulation with a micropulse laser may facilitate Hsp70 expression in the RPE without inducing cellular damage.

  8. Heat waves imposed during early pod development in soybean (Glycine max) cause significant yield loss despite a rapid recovery from oxidative stress.

    Science.gov (United States)

    Siebers, Matthew H; Yendrek, Craig R; Drag, David; Locke, Anna M; Rios Acosta, Lorena; Leakey, Andrew D B; Ainsworth, Elizabeth A; Bernacchi, Carl J; Ort, Donald R

    2015-08-01

    Heat waves already have a large impact on crops and are predicted to become more intense and more frequent in the future. In this study, heat waves were imposed on soybean using infrared heating technology in a fully open-air field experiment. Five separate heat waves were applied to field-grown soybean (Glycine max) in central Illinois, three in 2010 and two in 2011. Thirty years of historical weather data from Illinois were analyzed to determine the length and intensity of a regionally realistic heat wave resulting in experimental heat wave treatments during which day and night canopy temperatures were elevated 6 °C above ambient for 3 days. Heat waves were applied during early or late reproductive stages to determine whether and when heat waves had an impact on carbon metabolism and seed yield. By the third day of each heat wave, net photosynthesis (A), specific leaf weight (SLW), and leaf total nonstructural carbohydrate concentration (TNC) were decreased, while leaf oxidative stress was increased. However, A, SLW, TNC, and measures of oxidative stress were no different than the control ca. 12 h after the heat waves ended, indicating rapid physiological recovery from the high-temperature stress. That end of season seed yield was reduced (~10%) only when heat waves were applied during early pod developmental stages indicates the yield loss had more to do with direct impacts of the heat waves on reproductive process than on photosynthesis. Soybean was unable to mitigate yield loss after heat waves given during late reproductive stages. This study shows that short high-temperature stress events that reduce photosynthesis and increase oxidative stress resulted in significant losses to soybean production in the Midwest, U.S. The study also suggests that to mitigate heat wave-induced yield loss, soybean needs improved reproductive and photosynthetic tolerance to high but increasingly common temperatures. Published 2015. This article is a U.S. Government work and is

  9. Microstructural evolution and microhardness of a selective-laser-melted Ti–6Al–4V alloy after post heat treatments

    Energy Technology Data Exchange (ETDEWEB)

    Wu, S.Q.; Lu, Y.J.; Gan, Y.L.; Huang, T.T. [Key Laboratory of Optoelectronic Materials Chemical and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou (China); Zhao, C.Q. [Key Laboratory of Optoelectronic Materials Chemical and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou (China); College Materials Science and Engineering, Fujian Normal University, Fuzhou (China); Lin, J.J.; Guo, S. [Key Laboratory of Optoelectronic Materials Chemical and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou (China); Lin, J.X., E-mail: franklin@fjirsm.ac.cn [Key Laboratory of Optoelectronic Materials Chemical and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou (China)

    2016-07-05

    Microstructure and hardness of a powder-bed-type selective laser melted Ti–6Al–4V alloy after post heat treatments at from 300 °C to 1020 °C were systematically investigated by using optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM) and Vickers hardness (HV) tester. Long columnar original β grains together with the inside dominated parallel acicular martensite in the side view, and chessboard pattern in the top view, were found in the as-received specimen. The subtransus heat treatment does not enable modification of the morphology of the original columnar β grain, only leading to the acicular α′ martensite decomposition into the α platelet and whether surrounded β phase or transformed α′ phase depending on the heating temperature; while the supertransus heat treatment would thoroughly break up the original long columnar β grain, leaving only big original equiaxial β grain filled with the new forming weave-type acicular α′ martensite like the supertransus heat treated wrought specimen. Vickers hardness evolution strictly follows the trend of the microstructural change as the heating temperature increasing, and the double peak phenomenon of the Hardness–Temperature plot should be attributed to substructural refinement effect at around 500 °C, martensitic refinement effect at around 1000 °C, and softening effect resulting from the completely decomposition of the martensite at around 875 °C. - Highlights: • Heat treatment affects microstructure and hardness of the SLM Ti–6Al–4V alloy. • The as-received alloy is of columnar β grains with the inside acicular martensites. • The as-received martensites decompose into α and β/β{sub t} plates during heating. • Double peak phenomenon appears in the Microhardness–Temperature plot.

  10. Heat

    CERN Document Server

    Lawrence, Ellen

    2016-01-01

    Is it possible to make heat by rubbing your hands together? Why does an ice cube melt when you hold it? In this title, students will conduct experiments to help them understand what heat is. Kids will also investigate concepts such as which materials are good at conducting heat and which are the best insulators. Using everyday items that can easily be found around the house, students will transform into scientists as they carry out step-by-step experiments to answer interesting questions. Along the way, children will pick up important scientific skills. Heat includes seven experiments with detailed, age-appropriate instructions, surprising facts and background information, a "conclusions" section to pull all the concepts in the book together, and a glossary of science words. Colorful, dynamic designs and images truly put the FUN into FUN-damental Experiments.

  11. EXTRACTING ROOF PARAMETERS AND HEAT BRIDGES OVER THE CITY OF OLDENBURG FROM HYPERSPECTRAL, THERMAL, AND AIRBORNE LASER SCANNING DATA

    Directory of Open Access Journals (Sweden)

    L. Bannehr

    2012-09-01

    Full Text Available Remote sensing methods are used to obtain different kinds of information about the state of the environment. Within the cooperative research project HiReSens, funded by the German BMBF, a hyperspectral scanner, an airborne laser scanner, a thermal camera, and a RGB-camera are employed on a small aircraft to determine roof material parameters and heat bridges of house tops over the city Oldenburg, Lower Saxony. HiReSens aims to combine various geometrical highly resolved data in order to achieve relevant evidence about the state of the city buildings. Thermal data are used to obtain the energy distribution of single buildings. The use of hyperspectral data yields information about material consistence of roofs. From airborne laser scanning data (ALS digital surface models are inferred. They build the basis to locate the best orientations for solar panels of the city buildings. The combination of the different data sets offers the opportunity to capitalize synergies between differently working systems. Central goals are the development of tools for the collection of heat bridges by means of thermal data, spectral collection of roofs parameters on basis of hyperspectral data as well as 3D-capture of buildings from airborne lasers scanner data. Collecting, analyzing and merging of the data are not trivial especially not when the resolution and accuracy is aimed in the domain of a few decimetre. The results achieved need to be regarded as preliminary. Further investigations are still required to prove the accuracy in detail.

  12. Spatially-Resolved Proteomics: Rapid Quantitative Analysis of Laser Capture Microdissected Alveolar Tissue Samples

    Energy Technology Data Exchange (ETDEWEB)

    Clair, Geremy; Piehowski, Paul D.; Nicola, Teodora; Kitzmiller, Joseph A.; Huang, Eric L.; Zink, Erika M.; Sontag, Ryan L.; Orton, Daniel J.; Moore, Ronald J.; Carson, James P.; Smith, Richard D.; Whitsett, Jeffrey A.; Corley, Richard A.; Ambalavanan, Namasivayam; Ansong, Charles

    2016-12-22

    Global proteomics approaches allow characterization of whole tissue lysates to an impressive depth. However, it is now increasingly recognized that to better understand the complexity of multicellular organisms, global protein profiling of specific spatially defined regions/substructures of tissues (i.e. spatially-resolved proteomics) is essential. Laser capture microdissection (LCM) enables microscopic isolation of defined regions of tissues preserving crucial spatial information. However, current proteomics workflows entail several manual sample preparation steps and are challenged by the microscopic mass-limited samples generated by LCM, and that impact measurement robustness, quantification, and throughput. Here, we coupled LCM with a fully automated sample preparation workflow that with a single manual step allows: protein extraction, tryptic digestion, peptide cleanup and LC-MS/MS analysis of proteomes from microdissected tissues. Benchmarking against the current state of the art in ultrasensitive global proteomic analysis, our approach demonstrated significant improvements in quantification and throughput. Using our LCM-SNaPP proteomics approach, we characterized to a depth of more than 3,400 proteins, the ontogeny of protein changes during normal lung development in laser capture microdissected alveolar tissue containing ~4,000 cells per sample. Importantly, the data revealed quantitative changes for 350 low abundance transcription factors and signaling molecules, confirming earlier transcript-level observations and defining seven modules of coordinated transcription factor/signaling molecule expression patterns, suggesting that a complex network of temporal regulatory control directs normal lung development with epigenetic regulation fine-tuning pre-natal developmental processes. Our LCM-proteomics approach facilitates efficient, spatially-resolved, ultrasensitive global proteomics analyses in high-throughput that will be enabling for several clinical and

  13. Effect of radiant heat on conventional glass ionomer cements during setting by using a blue light diode laser system (445 nm).

    Science.gov (United States)

    Dionysopoulos, Dimitrios; Tolidis, Kosmas; Strakas, Dimitrios; Gerasimou, Paris; Sfeikos, Thrasyvoulos; Gutknecht, Norbert

    2017-04-01

    The aim of this in vitro study was to evaluate the effect of radiant heat on surface hardness of three conventional glass ionomer cements (GICs) by using a blue diode laser system (445 nm) and a light-emitting diode (LED) unit. Additionally, the safety of the laser treatment was evaluated. Thirty disk-shaped specimens were prepared of each tested GIC (Equia Fil, Ketac Universal Aplicap and Riva Self Cure). The experimental groups (n = 10) of the study were as follows: group 1 was the control group of the study; in group 2, the specimens were irradiated for 60 s at the top surface using a LED light-curing unit; and in group 3, the specimens were irradiated for 60 s at the top surface using a blue light diode laser system (445 nm). Statistical analysis was performed using one-way ANOVA and Tukey post-hoc tests at a level of significance of a = 0.05. Radiant heat treatments, with both laser and LED devices, increased surface hardness (p diode laser treatment was seemed to be more effective compared to LED treatment. There were no alterations in surface morphology or chemical composition after laser treatment. The tested radiant heat treatment with a blue diode laser may be advantageous for the longevity of GIC restorations. The safety of the use of blue diode laser for this application was confirmed.

  14. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Plasma heating near a metal target by nanosecond pulses of the first, second, and fourth Nd-laser harmonics

    Science.gov (United States)

    Bufetov, Igor'A.; Bufetova, G. A.; Kravtsov, S. B.; Fyodorov, V. B.; Fomin, V. K.

    1995-08-01

    Measurements were made of the electron temperature Te of a laser plasma formed on the surface of a metal target by the action of nanosecond pulses of wavelengths λ = 1060, 530, and 265 nm. The laser radiation intensity was I approx 109—1013 W cm-2. The electron temperature was determined from the emf of a double charge layer at the plasma boundary. Within the limits of the scatter of the experimental results, the plasma temperature was independent of the laser radiation wavelength (in the range 1060-265 nm). The dependence of this temperature on the radiation intensity obeyed approximately Te propto I1/3 throughout the investigated range.

  15. Time evolution of the distribution function for stochastically heated relativistic electrons in a laser field of picosecond duration

    Science.gov (United States)

    Borisenko, L. A.; Borisenko, N. G.; Mikhailov, Yu. A.; Orekhov, A. S.; Sklizkov, G. V.; Chekmarev, A. M.; Shapkin, A. A.

    2017-11-01

    We report a numerical analysis of the stochastic acceleration of electrons, stipulated by a random change in the phase of the force acting on the electron. The main source of randomness is the random spatial distribution of electromagnetic fields in the focal region of multimode laser radiation. A typical frequency of the random phase change corresponding to the maximum impact of the effect under consideration lies in the range of (0.25 – 0.5)ν (ν is the radiation frequency of a neodymium laser). A wave packet model convenient for calculations taking into account the radiative transitions of the neodymium ion is proposed. The dependence of the average energy of relativistic electrons on the flux density in the range of 1015 – 1018 W cm‑2 is calculated. The time dependence of the average electron energy during the laser pulse in the form of approximating formulas is constructed. The typical time for the development of stochastic heating of electrons is determined. It is found that the stochastic acceleration process weakly depends on the laser pulse duration, when the latter exceeds several hundred periods of the electromagnetic wave.

  16. Rapid acclimation of juvenile corals to CO2 -mediated acidification by upregulation of heat shock protein and Bcl-2 genes.

    Science.gov (United States)

    Moya, A; Huisman, L; Forêt, S; Gattuso, J-P; Hayward, D C; Ball, E E; Miller, D J

    2015-01-01

    Corals play a key role in ocean ecosystems and carbonate balance, but their molecular response to ocean acidification remains unclear. The only previous whole-transcriptome study (Moya et al. Molecular Ecology, 2012; 21, 2440) documented extensive disruption of gene expression, particularly of genes encoding skeletal organic matrix proteins, in juvenile corals (Acropora millepora) after short-term (3 d) exposure to elevated pCO2 . In this study, whole-transcriptome analysis was used to compare the effects of such 'acute' (3 d) exposure to elevated pCO2 with a longer ('prolonged'; 9 d) period of exposure beginning immediately post-fertilization. Far fewer genes were differentially expressed under the 9-d treatment, and although the transcriptome data implied wholesale disruption of metabolism and calcification genes in the acute treatment experiment, expression of most genes was at control levels after prolonged treatment. There was little overlap between the genes responding to the acute and prolonged treatments, but heat shock proteins (HSPs) and heat shock factors (HSFs) were over-represented amongst the genes responding to both treatments. Amongst these was an HSP70 gene previously shown to be involved in acclimation to thermal stress in a field population of another acroporid coral. The most obvious feature of the molecular response in the 9-d treatment experiment was the upregulation of five distinct Bcl-2 family members, the majority predicted to be anti-apoptotic. This suggests that an important component of the longer term response to elevated CO2 is suppression of apoptosis. It therefore appears that juvenile A. millepora have the capacity to rapidly acclimate to elevated pCO2 , a process mediated by upregulation of specific HSPs and a suite of Bcl-2 family members. © 2014 John Wiley & Sons Ltd.

  17. Effects of particle size and laser wavelength on heating of silver ...

    Indian Academy of Sciences (India)

    2016-07-15

    Jul 15, 2016 ... In this study, optical properties of spherical silver nanoparticles at laser radiation wavelengths have been examined for some laser applications in nanomedicine and nanotechnology by using Mie theory. Calcula- tion of absorption factors and their maximal tempe- ratures when the radii of the nanoparticles ...

  18. Validation of non-local electron heat conduction model for radiation MHD simulation in magnetized laser plasma

    Science.gov (United States)

    Nagatomo, Hideo; Matsuo, Kazuki; Nicolai, Pilippe; Asahina, Takashi; Fujioka, Shinsuke

    2017-10-01

    In laser plasma physics, application of an external magnetic field is an attractive method for various research of high energy density physics including fast ignition. Meanwhile, in the high intense laser plasma the behavior of hot electron cannot be ignored. In the radiation hydrodynamic simulation, a classical electron conduction model, Spitzer-Harm model has been used in general. However the model has its limit, and modification of the model is necessary if it is used beyond the application limit. Modified SNB model, which considering the influence of magnetic field is applied to 2-D radiation magnetohydrodynamic code PINOCO. Some experiments related the non-local model are carried out at GXII, Osaka University. In this presentation, these experimental results are shown briefly. And comparison between simulation results considering the non-local electron heat conduction mode are discussed. This study was supported JSPS KAKENHI Grant No. 17K05728.

  19. Infrared emissivity studies of melting thresholds and structural changes of aluminium and copper samples heated by femtosecond laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Hallo, L; Riou, O; Stenz, C; Tikhonchuk, V T [Centre Lasers Intenses et Applications, UMR 5107 CNRS-Universite Bordeaux 1-CEA, Universite Bordeaux 1, 351 Cours de la Liberation, 33405 Talence Cedex (France)

    2006-12-21

    We propose a new method for studies of laser-induced heating and melting of metallic foils. The method is based on time-integrated measurements of the surface infrared thermal emission. The experimental data are compared with a model where two equations describe the evolution of electron and lattice temperatures and the emissivity is found from the Drude model with the temperature-dependent electron collision frequency. A good agreement between the experimental data and the model is found for the aluminium samples. It is less satisfactory for the copper, but a signature of phase melting can also be pointed out. A multi-pulse laser irradiation study indicates significant changes in the surface emittance, related to preheating, oxidation and/or chemical modification of the copper sample. The proposed method is relatively simple and complementary to the pump-probe technique.

  20. Formation of the domain structure in CLN under the pyroelectric field induced by pulse infrared laser heating

    Energy Technology Data Exchange (ETDEWEB)

    Shur, V. Ya.; Kosobokov, M. S.; Mingaliev, E. A.; Karpov, V. R. [Institute of Natural Sciences, Ural Federal University, Ekaterinburg, 620000 (Russian Federation)

    2015-10-15

    The evolution of the self-assembled quasi-regular micro- and nanodomain structures after pulse infrared laser irradiation in congruent lithium niobate crystal was studied by in situ optical observation. Several scenarios of domain kinetics represented covering of the irradiated zone by nets of the separated domain chains and rays have been revealed. The time dependence of the total domain length was analyzed in terms of modified Kolmogorov-Avrami theory. The domain structure evolution was attributed to the action of pyroelectric field appeared during cooling. The time dependence of the spatial distribution of the pyroelectric field during pulse laser heating and subsequent cooling was calculated by finite element method. The results of computer simulation allowed us to explain the experimental results and can be used for creation of tailored domain structures thus opening the new abilities of the submicron-scale domain engineering in ferroelectrics.

  1. Free-space laser communication system with rapid acquisition based on astronomical telescopes.

    Science.gov (United States)

    Wang, Jianmin; Lv, Junyi; Zhao, Guang; Wang, Gang

    2015-08-10

    The general structure of a free-space optical (FSO) communication system based on astronomical telescopes is proposed. The light path for astronomical observation and for communication can be easily switched. A separate camera is used as a star sensor to determine the pointing direction of the optical terminal's antenna. The new system exhibits rapid acquisition and is widely applicable in various astronomical telescope systems and wavelengths. We present a detailed analysis of the acquisition time, which can be decreased by one order of magnitude compared with traditional optical communication systems. Furthermore, we verify software algorithms and tracking accuracy.

  2. Rapid sealing of porcine renal blood vessels, ex vivo, using a high power, 1470-nm laser, and laparoscopic prototype

    Science.gov (United States)

    Hardy, Luke A.; Hutchens, Thomas C.; Larson, Eric R.; Gonzalez, David A.; Chang, Chun-Hung; Nau, William H.; Fried, Nathaniel M.

    2017-05-01

    Energy-based, radiofrequency (RF) and ultrasonic (US) devices currently provide rapid sealing of blood vessels during laparoscopic procedures. We are exploring infrared lasers as an alternate energy modality for vessel sealing, capable of generating less collateral thermal damage. Previous studies demonstrated feasibility of sealing vessels in an in vivo porcine model using a 1470-nm laser. However, the initial prototype was designed for testing in open surgery and featured tissue clasping and light delivery mechanisms incompatible with laparoscopic surgery. In this study, a laparoscopic prototype similar to devices currently in surgical use was developed, and performance tests were conducted on porcine renal blood vessels, ex vivo. The 5-mm outer-diameter laparoscopic prototype featured a traditional Maryland jaw configuration that enables tissue manipulation and blunt dissection. Laser energy was delivered through a 550-μm-core-diameter optical fiber with side-delivery from the lower jaw and beam dimensions of 18-mm length×1.2-mm width. The 1470-nm diode laser delivered 68 W with 3-s activation time, consistent with vessel seal times associated with RF and US-based devices. A total of 69 fresh porcine renal vessels with mean diameter of 3.3±1.7 mm were tested, ex vivo. Vessels smaller than 5-mm diameter were consistently sealed (48/51) with burst pressures greater than malignant hypertension blood pressure (180 mmHg), averaging 1038±474 mmHg. Vessels larger than 5 mm were not consistently sealed (6/18), yielding burst pressures of only 174±221 mmHg. Seal width, thermal damage zone, and thermal spread averaged 1.7±0.8, 3.4±0.7, and 1.0±0.4 mm, respectively. Results demonstrated that the 5-mm optical laparoscopic prototype consistently sealed vessels less than 5-mm diameter with low thermal spread. Further in vivo studies are planned to test the performance across a variety of vessels and tissues.

  3. Rapid determination of gizzerosine in fish meals using microchip capillary electrophoresis with laser-induced fluorescence detection.

    Science.gov (United States)

    Xiao, Meng-Wei; Bai, Xiao-Lin; Xu, Pei-Li; Zhao, Yan; Yang, Li; Liu, Yi-Ming; Liao, Xun

    2017-05-01

    Sensitive detection of gizzerosine, a causative agent for deadly gizzard erosion in chicken feeds, is very important to the poultry industry. In this work, a new method was developed based on microchip capillary electrophoresis (MCE) with laser-induced fluorescence (LIF) detection for rapid analysis of gizzerosine, a biogenic amine in fish meals. The MCE separation was performed on a glass microchip using sodium dodecyl sulfate (SDS) as dynamic coating modifier. Separation conditions, including running buffer pH and concentration, SDS concentration, and the separation voltage were investigated to achieve fast and sensitive quantification of gizzerosine. The assay proposed was very quick and could be completed within 65 s. A linear calibration curve was obtained in the range from 0.04 to 1.8 μg ml-1 gizzerosine. The detection limit was 0.025 μg ml-1 (0.025 mg kg-1), which was far more sensitive than those previously reported. Gizzerosine was well separated from other endogenous components in fish meal samples. Recovery of gizzerosine from this sample matrix (n = 3) was determined to be 97.2-102.8%. The results from analysing fish meal samples indicated that the present MCE-LIF method might hold the potential for rapid detection of gizzerosine in poultry feeds.

  4. Laser processing and analysis of materials

    CERN Document Server

    Duley, W W

    1983-01-01

    It has often been said that the laser is a solution searching for a problem. The rapid development of laser technology over the past dozen years has led to the availability of reliable, industrially rated laser sources with a wide variety of output characteristics. This, in turn, has resulted in new laser applications as the laser becomes a familiar processing and analytical tool. The field of materials science, in particular, has become a fertile one for new laser applications. Laser annealing, alloying, cladding, and heat treating were all but unknown 10 years ago. Today, each is a separate, dynamic field of research activity with many of the early laboratory experiments resulting in the development of new industrial processing techniques using laser technology. Ten years ago, chemical processing was in its infancy awaiting, primarily, the development of reliable tunable laser sources. Now, with tunability over the entire spectrum from the vacuum ultraviolet to the far infrared, photo­ chemistry is undergo...

  5. Laser-Induced Breakdown Spectroscopy for Rapid Discrimination of Heavy-Metal-Contaminated Seafood Tegillarca granosa

    Directory of Open Access Journals (Sweden)

    Guoli Ji

    2017-11-01

    Full Text Available Tegillarca granosa samples contaminated artificially by three kinds of toxic heavy metals including zinc (Zn, cadmium (Cd, and lead (Pb were attempted to be distinguished using laser-induced breakdown spectroscopy (LIBS technology and pattern recognition methods in this study. The measured spectra were firstly processed by a wavelet transform algorithm (WTA, then the generated characteristic information was subsequently expressed by an information gain algorithm (IGA. As a result, 30 variables obtained were used as input variables for three classifiers: partial least square discriminant analysis (PLS-DA, support vector machine (SVM, and random forest (RF, among which the RF model exhibited the best performance, with 93.3% discrimination accuracy among those classifiers. Besides, the extracted characteristic information was used to reconstruct the original spectra by inverse WTA, and the corresponding attribution of the reconstructed spectra was then discussed. This work indicates that the healthy shellfish samples of Tegillarca granosa could be distinguished from the toxic heavy-metal-contaminated ones by pattern recognition analysis combined with LIBS technology, which only requires minimal pretreatments.

  6. Development of a model system for rapid assessment of insect mortality in heated controlled atmosphere quarantine treatments.

    Science.gov (United States)

    Neven, Lisa G

    2008-04-01

    The development of postharvest quarantine treatments can be both expensive and time-consuming. It is necessary to determine the species and stage of the pest most tolerant to the treatment, if more than one species is the target of the treatment. Initial laboratory studies often include infesting the commodity with various egg and larval stages of the pest and performing treatments and evaluations of the fruit. In collaboration with others, I have previously developed combination high temperature under controlled atmosphere treatments against two quarantine pests in apples (Malus spp.) and peaches and nectarines (both Prunus spp.). I decided to develop an artificial system that can be used for these initial tests without the need for infesting large quantities of the fruit. I tested the system on the immature stages of the pests under regular air and controlled atmospheres by using the controlled atmosphere water bath system. This system can be used for rapid assessment of the most tolerant stage and species of a pest to a combination heat and controlled atmosphere treatment without the expense of infesting, treating, and evaluating the commodity.

  7. Monitoring Temperature in High Enthalpy Arc-heated Plasma Flows using Tunable Diode Laser Absorption Spectroscopy

    Science.gov (United States)

    Martin, Marcel Nations; Chang, Leyen S.; Jeffries, Jay B.; Hanson, Ronald K.; Nawaz, Anuscheh; Taunk, Jaswinder S.; Driver, David M.; Raiche, George

    2013-01-01

    A tunable diode laser sensor was designed for in situ monitoring of temperature in the arc heater of the NASA Ames IHF arcjet facility (60 MW). An external cavity diode laser was used to generate light at 777.2 nm and laser absorption used to monitor the population of electronically excited oxygen atoms in an air plasma flow. Under the assumption of thermochemical equilibrium, time-resolved temperature measurements were obtained on four lines-of-sight, which enabled evaluation of the temperature uniformity in the plasma column for different arcjet operating conditions.

  8. Reproducibility of Cutaneous Vascular Conductance Responses to Slow Local Heating Assessed Using seven-Laser Array Probes.

    Science.gov (United States)

    Dawson, Ellen A; Low, David A; Meeuwis, Iris H M; Kerstens, Floor G; Atkinson, Ceri L; Cable, Nigel Timothy; Green, Daniel J; Thijssen, Dick H J

    2015-05-01

    Gradual local heating of the skin induces a largely NO-mediated vasodilatation. However, use of this assessment of microvascular health is limited because little is known about its reproducibility. Healthy volunteers (n = 9) reported twice to the laboratory. CVC, derived from laser Doppler flux and mean arterial pressure, was examined in response to a standardized local heating protocol (0.5°C per 150 second from 33°C to 42°C, followed by 20 minutes at 44°C). Skin responses were examined at two locations on the forearm (between-site). Heating was repeated after a break of 24-72 hours (between-day). Reproducibility of skin responses at 33-42°C is presented for absolute CVC and relative CVC responses corrected for maximal CVC at 44°C (%CVCmax ). Between-day reproducibility of baseline CVC and %CVCmax for both sites was relatively poor (22-30%). At 42°C, CVC and %CVCmax responses showed less variation (9-19%), whilst absolute CVC responses at 44°C were 14-17%. Between-day variation for %CVCmax increased when using data from site 1 on day 1, but site 2 on the subsequent day (25%). Day-to-day reproducibility of baseline laser Doppler-derived skin perfusion responses is poor, but acceptable when absolute and relative skin perfusion to a local gradual heating protocol is utilized and site-to-site variation is minimized. © 2015 John Wiley & Sons Ltd.

  9. The characterization of neural tissue ablation rate and corresponding heat affected zone of a 2 micron Tm3+ doped fiber laser(Conference Presentation)

    Science.gov (United States)

    Marques, Andrew J.; Jivraj, Jamil; Reyes, Robnier; Ramjist, Joel; Gu, Xijia J.; Yang, Victor X. D.

    2017-02-01

    Tissue removal using electrocautery is standard practice in neurosurgery since tissue can be cut and cauterized simultaneously. Thermally mediated tissue ablation using lasers can potentially possess the same benefits but with increased precision. However, given the critical nature of the spine, brain, and nerves, the effects of direct photo-thermal interaction on neural tissue needs to be known, yielding not only high precision of tissue removal but also increased control of peripheral heat damage. The proposed use of lasers as a neurosurgical tool requires that a common ground is found between ablation rates and resulting peripheral heat damage. Most surgical laser systems rely on the conversion of light energy into heat resulting in both desirable and undesirable thermal damage to the targeted tissue. Classifying the distribution of thermal energy in neural tissue, and thus characterizing the extent of undesirable thermal damage, can prove to be exceptionally challenging considering its highly inhomogenous composition when compared to other tissues such as muscle and bone. Here we present the characterization of neural tissue ablation rate and heat affected zone of a 1.94 micron thulium doped fiber laser for neural tissue ablation. In-Vivo ablation of porcine cerebral cortex is performed. Ablation volumes are studied in association with laser parameters. Histological samples are taken and examined to characterize the extent of peripheral heat damage.

  10. The theory of laser materials processing heat and mass transfer in modern technology

    CERN Document Server

    Schulz, Wolfgang

    2017-01-01

    The revised edition of this important reference volume presents an expanded overview of the analytical and numerical approaches employed when exploring and developing modern laser materials processing techniques. The book shows how general principles can be used to obtain insight into laser processes, whether derived from fundamental physical theory or from direct observation of experimental results. The book gives readers an understanding of the strengths and limitations of simple numerical and analytical models that can then be used as the starting-point for more elaborate models of specific practical, theoretical or commercial value. Following an introduction to the mathematical formulation of some relevant classes of physical ideas, the core of the book consists of chapters addressing key applications in detail: cutting, keyhole welding, drilling, arc and hybrid laser-arc welding, hardening, cladding and forming. The second edition includes a new a chapter on glass cutting with lasers, as employed in the ...

  11. INVESTIGATION OF THE PROCESS OF SELECTIVE HEATING BY IMPULSE LASER OF SPHERICAL POWDERS OF TITANIUM

    Directory of Open Access Journals (Sweden)

    R. P. Bykov

    2010-01-01

    Full Text Available The technological characteristics of installation of selective laser sintering are given. It is shown that the results of selective sintering are the coverings with penetrable porous structure.

  12. Influence of laser parameters on selective retinal treatment using single-phase heat transfer analyses.

    Science.gov (United States)

    Banerjee, Rupak K; Zhu, Liang; Gopalakrishnan, Pradeep; Kazmierczak, Michael J

    2007-05-01

    Selective thermal treatment to retina is induced by short pulsed lasers to denaturize retinal pigment epithelium (RPE) selectively, while sparing the sensitive photoreceptors. The problem associated with the usage of short pulsed laser is the difficulty in determining the correct dosimetry parameters. This study quantifies the influence of laser parameters over the therapeutic range. The laser-tissue interaction is numerically investigated by analyzing the transient temperature in ocular tissues during the treatment. The rate process analysis for thermal injury is employed to estimate the selective damage of retina. The contours of Arrhenius integral value (Omeg/ Omegamax) presented in this study show both the area and magnitude of damage caused by various laser parameters. Results reveal that the 2 micros pulsed laser with green wavelength and Gaussian profile is relatively more effective for selective retinal treatment. The repetition frequency of 100 Hz is found to produce selectively RPE damage, while higher frequencies produce collateral damage to neural retina and choroid located within 2 microm from the RPE interface.

  13. Rapid identification and classification of Campylobacter spp. using laser optical scattering technology.

    Science.gov (United States)

    He, Yiping; Reed, Sue; Bhunia, Arun K; Gehring, Andrew; Nguyen, Ly-Huong; Irwin, Peter L

    2015-05-01

    Campylobacter jejuni and Campylobacter coli are the two important species responsible for most of the Campylobacter infections in humans. Reliable isolation and detection of Campylobacter spp. from food samples are challenging due to the interferences from complex food substances and the fastidious growth requirements of this organism. In this study, a novel biosensor-based detection called BARDOT (BActerial Rapid Detection using Optical scattering Technology) was developed for high-throughput screening of Campylobacter colonies grown on an agar plate without disrupting the intact colonies. Image pattern characterization and principal component analysis (PCA) of 6909 bacterial colonies showed that the light scatter patterns of C. jejuni and C. coli were strikingly different from those of Salmonella spp., Escherichia coli O157:H7, and Listeria monocytogenes. Examination of a mixed culture of these microorganisms revealed 85% (34/40) accuracy in differentiating Campylobacter from the other three major foodborne pathogens based on the similarity to the scatter patterns in an established library. The application of BARDOT in real food has been addressed through the analysis of Campylobacter spiked ground chicken and naturally contaminated fresh chicken pieces. Combined with real-time PCR verification, BARDOT was able to identify Campylobacter isolates from retail chicken. Moreover, applying passive filtration to food samples facilitated the isolation of pure Campylobacter colonies and therefore overcame the interference of the food matrix on BARDOT analysis. Published by Elsevier Ltd.

  14. Reliable and reproducible method for rapid identification of Nocardia species by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

    Science.gov (United States)

    Toyokawa, Masahiro; Kimura, Keigo; Nishi, Isao; Sunada, Atsuko; Ueda, Akiko; Sakata, Tomomi; Asari, Seishi

    2013-01-01

    Recently, matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been challenged for the identification of Nocardia species. However, the standard ethanol-formic acid extraction alone is insufficient in allowing the membrane proteins of Nocardia species to be ionized by the matrix. We therefore aimed to establish our new extraction method for the MALDI-TOF MS-based identification of Nocardia species isolates. Our modified extraction procedure is through dissociation in 0.5% Tween-20 followed by bacterial heat-inactivation, mechanical breaking of the cell wall by acid-washed glass beads and protein extraction with formic acid and acetonitrile. As reference methods for species identification, full-length 16S rRNA gene sequencing and some phenotypical tests were used. In a first step, we made our own Nocardia database by analyzing 13 strains (13 different species including N. elegans, N. otitidiscaviarum, N. asiatica, N. abscessus, N. brasiliensis, N. thailandica, N. farcinica, N. nova, N. mikamii, N. cyriacigeorgica, N. asteroids, Nocardiopsis alba, and Micromonospora sp.) and registered to the MALDI BioTyper database. Then we established our database. The analysis of 12 challenge strains using the our database gave a 100% correct identification, including 8 strains identified to the species level and 4 strains to the genus level (N. elegans, N. nova, N. farcinica, Micromonospora sp.) according to the manufacture's log score specifications. In the estimation of reproducibility of our method intended for 4 strains, both within-run and between-run reproducibility were excellent. These data indicates that our method for rapid identification of Nocardia species is with reliability, reproducibility and cost effective.

  15. Effects of particle size and laser-induced heating on the Raman spectra of alpha quartz grains.

    Science.gov (United States)

    Chio, Chi Hong; Sharma, Shiv K; Lucey, Paul G; Muenow, David W

    2003-07-01

    Raman spectra of alpha-quartz (Qz) grains of various size (250 microm to Raman and micro-Raman systems. Frequency downshift and line broadening of the 464 cm(-1), v,(Si-O-Si) band are observed in the smallest size group (Raman lines is also used to estimate the vibrational temperature of the samples under different excitation power. The degree of laser-induced heating is more noticeable in the aggregates than in the individual grains with the use of medium-level laser excitation (< or = 150 mW). Heating diminishes with increasing grain size, and it can only be detected in grain aggregates between 11 and 20 microm in diameter using 150 mW excitation. Intensity studies of the v(s)(Si-O-Si) band using individual grains show no noticeable signs of grain size effects. However, grain size effects become an important factor in the study of aggregates in which spectral intensity diminishes with respect to decreasing grain size.

  16. Extending the binary collision algorithm to non-Spitzer systems and application to laser heating and damage

    Science.gov (United States)

    Russell, Alex; Schumacher, Douglass

    2017-08-01

    We have generalized the binary collision algorithm to accommodate arbitrary collision rates, enabling the accurate kinetic modeling of short range particle interactions in non-Spitzer systems. With this extension, we explore the effect of different collision models on simulating how ultra-intense lasers first begin to heat a target. The effect of collisions on plasma evolution is crucial for treating particle slowing, energy transport, and thermalization. The widely used binary collision algorithm provides a fast and computationally efficient method to include the effects of collisions between charged particles in kinetic simulations without requiring the particles to be in local thermal equilibrium already. However, it is "hardwired" to use Spitzer collision rates that are appropriate for hot, relatively dilute plasmas. This restriction prevents the Nanbu collision algorithm from accurately describing the initial heating of a cold target, a key problem for the study of laser damage or the generation of the warm dense matter state. We describe our approach for modifying the Nanbu collision algorithm and demonstrate the improved accuracy for copper targets.

  17. Microstructure of selective laser melted CM247LC nickel-based superalloy and its evolution through heat treatment

    Energy Technology Data Exchange (ETDEWEB)

    Divya, V.D., E-mail: dv272@cam.ac.uk [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Muñoz-Moreno, R.; Messé, O.M.D.M.; Barnard, J.S. [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Baker, S.; Illston, T. [Materials Solutions, Unit 8, Great Western Business Park, McKenzie Way, Worcester WR4 9GN (United Kingdom); Stone, H.J. [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom)

    2016-04-15

    The selective laser melting of high temperature alloys is of great interest to the aerospace industry as it offers the prospect of producing more complex geometries than can be achieved with other manufacturing methods. In this study, the microstructure of the nickel-based superalloy, CM247LC, has been characterised following selective laser melting and after a post deposition heat treatment below the γ′ solvus temperature. In the as-deposited state, scanning electron microscopy with electron backscatter diffraction revealed a fine, cellular microstructure with preferential alignment of 〈001〉 along the build direction. A high dislocation density was seen at the periphery of the cells, indicating substantial localised deformation of the material. Fine primary MC carbides were also observed in the inter-cellular regions. High-resolution transmission electron microscopy identified the occurrence of very fine γ′ precipitates, approximately 5 nm in diameter, dispersed within the gamma phase. After heat treatment, the elongated cell colonies were observed to partially coalesce, accompanied by a decrease in dislocation density, producing columnar grains along the build direction. Cuboidal γ′ precipitates approximately 500 nm in diameter were observed to form in the recrystallised grains, accompanied by larger γ′ precipitates on the grain boundaries.

  18. Study of temporal pulse shape effects on W using simulations and laser heating

    NARCIS (Netherlands)

    Yu, J. H.; De Temmerman, G.; Doerner, R. P.; van den Berg, M. A.

    2016-01-01

    Transient heat pulses with triangular, square, and ELM-like temporal shapes are investigated in order to further understand how transient plasma instabilities will affect plasma facing components in tokamaks. A solution to the 1D heat equation for triangular pulses allows the peak surface

  19. Rapid additive manufacturing of MR compatible multipinhole collimators with selective laser melting of tungsten powder.

    Science.gov (United States)

    Deprez, Karel; Vandenberghe, Stefaan; Van Audenhaege, Karen; Van Vaerenbergh, Jonas; Van Holen, Roel

    2013-01-01

    The construction of complex collimators with a high number of oblique pinholes is very labor intensive, expensive or is sometimes impossible with the current available techniques (drilling, milling or electric discharge machining). All these techniques are subtractive: one starts from solid plates and the material at the position of the pinholes is removed. The authors used a novel technique for collimator construction, called metal additive manufacturing. This process starts with a solid piece of tungsten on which a first layer of tungsten powder is melted. Each subsequent layer is then melted on the previous layer. This melting is done by selective laser melting at the locations where the CAD design file defines solid material. A complex collimator with 20 loftholes with 500 μm diameter pinhole opening was designed and produced (16 mm thick and 70 × 52 mm(2) transverse size). The density was determined, the production accuracy was measured (GOM ATOS II Triple Scan, Nikon AZ100M microscope, Olympus IMT200 microscope). Point source measurements were done by mounting the collimator on a SPECT detector. Because there is increasing interest in dual-modality SPECT-MR imaging, the collimator was also positioned in a 7T MRI scanner (Bruker Pharmascan). A uniform phantom was acquired using T1, T2, and T2* sequences to check for artifacts or distortion of the phantom images due to the collimator presence. Additionally, three tungsten sample pieces (250, 500, and 750 μm thick) were produced. The density, attenuation (140 keV beam), and uniformity (GE eXplore Locus SP micro-CT) of these samples were measured. The density of the collimator was equal to 17.31 ± 0.10 g∕cm(3) (89.92% of pure tungsten). The production accuracy ranges from -260 to +650 μm. The aperture positions have a mean deviation of 5 μm, the maximum deviation was 174 μm and the minimum deviation was -122 μm. The mean aperture diameter is 464 ± 19 μm. The calculated and measured sensitivity and

  20. In situ observation of the reaction of tantalum with nitrogen in a laser heated diamond anvil cell

    Energy Technology Data Exchange (ETDEWEB)

    Friedrich, Alexandra, E-mail: friedrich@kristall.uni-frankfurt.d [Institut fuer Geowissenschaften, Goethe-Universitaet Frankfurt, Altenhoeferallee 1, D-60438 Frankfurt am Main (Germany); Winkler, Bjoern; Bayarjargal, Lkhamsuren [Institut fuer Geowissenschaften, Goethe-Universitaet Frankfurt, Altenhoeferallee 1, D-60438 Frankfurt am Main (Germany); Juarez Arellano, Erick A. [Universidad del Papaloapan, Circuito Central 200, Parque Industrial, Tuxtepec 68301 (Mexico); Morgenroth, Wolfgang; Biehler, Jasmin; Schroeder, Florian [Institut fuer Geowissenschaften, Goethe-Universitaet Frankfurt, Altenhoeferallee 1, D-60438 Frankfurt am Main (Germany); Yan, Jinyuan; Clark, Simon M. [Advanced Light Source, Lawrence Berkeley National Laboratory, MS6R2100, 1 Cyclotron Road, Berkeley, CA 94720-8226 (United States)

    2010-07-16

    Tantalum nitrides were formed by reaction of the elements at pressures between 9(1) and 12.7(5) GPa and temperatures >1600-2000 K in the laser-heated diamond anvil cell. The incorporation of small amount of nitrogen in the tantalum structure was identified as the first reaction product on weak laser irradiation. Subsequent laser heating led to the formation of hexagonal {beta}-Ta{sub 2}N and orthorhombic {eta}-Ta{sub 2}N{sub 3}, which was the stable phase at pressures up to 27 GPa and high temperatures. No evidence was found for the presence of {epsilon}-TaN, {theta}-TaN, {delta}-TaN, Ta{sub 3}N{sub 5}-I or Ta{sub 3}N{sub 5}-II, which was predicted to be the stable phase at P>17 GPa and T=2800 K, at the P,T-conditions of this experiment. The bulk modulus of {eta}-Ta{sub 2}N{sub 3} was determined to be B{sub 0}=319(6) GPa from a 2nd order Birch-Murnaghan equation of state fit to the experimental data, while quantum mechanical calculations using the density functional theory gave a bulk modulus of B{sub 0}=348.0(9) GPa for a 2nd-order fit or B{sub 0}=339(1) GPa and B{sup '}=4.67(9) for a 3rd-order fit. The values show the large incompressibility of this high-pressure phase. From the DFT data the structural compression mechanism could be determined.

  1. Low-Cost and Rapid Fabrication of Metallic Nanostructures for Sensitive Biosensors Using Hot-Embossing and Dielectric-Heating Nanoimprint Methods

    Directory of Open Access Journals (Sweden)

    Kuang-Li Lee

    2017-07-01

    Full Text Available We propose two approaches—hot-embossing and dielectric-heating nanoimprinting methods—for low-cost and rapid fabrication of periodic nanostructures. Each nanofabrication process for the imprinted plastic nanostructures is completed within several seconds without the use of release agents and epoxy. Low-cost, large-area, and highly sensitive aluminum nanostructures on A4 size plastic films are fabricated by evaporating aluminum film on hot-embossing nanostructures. The narrowest bandwidth of the Fano resonance is only 2.7 nm in the visible light region. The periodic aluminum nanostructure achieves a figure of merit of 150, and an intensity sensitivity of 29,345%/RIU (refractive index unit. The rapid fabrication is also achieved by using radio-frequency (RF sensitive plastic films and a commercial RF welding machine. The dielectric-heating, using RF power, takes advantage of the rapid heating/cooling process and lower electric power consumption. The fabricated capped aluminum nanoslit array has a 5 nm Fano linewidth and 490.46 nm/RIU wavelength sensitivity. The biosensing capabilities of the metallic nanostructures are further verified by measuring antigen–antibody interactions using bovine serum albumin (BSA and anti-BSA. These rapid and high-throughput fabrication methods can benefit low-cost, highly sensitive biosensors and other sensing applications.

  2. Time-resolved microscopy of fs-laser-induced heat flows in glasses

    Science.gov (United States)

    Bonse, Jörn; Seuthe, Thomas; Grehn, Moritz; Eberstein, Markus; Rosenfeld, Arkadi; Mermillod-Blondin, Alexandre

    2018-01-01

    Time-resolved phase-contrast microscopy is employed to visualize spatio-temporal thermal transients induced by tight focusing of a single Ti:sapphire fs-laser pulse into a solid dielectric sample. This method relies on the coupling of the refractive index change and the sample temperature through the thermo-optic coefficient d n/d T. The thermal transients are studied on a timescale ranging from 10 ns up to 0.1 ms after laser excitation. Beyond providing direct insights into the laser-matter interaction, analyzing the results obtained also enables quantifying the local thermal diffusivity of the sample on a micrometer scale. Studies conducted in different solid dielectrics, namely amorphous fused silica (a-SiO2), a commercial borosilicate glass (BO33, Schott), and a custom alkaline earth silicate glass (NaSi66), illustrate the applicability of this approach to the investigation of various glassy materials.

  3. Relationship between 578-nm (copper vapor) laser beam geometry and heat distribution within biological tissues

    Science.gov (United States)

    Ilyasov, Ildar K.; Prikhodko, Constantin V.; Nevorotin, Alexey J.

    1995-01-01

    Monte Carlo (MC) simulation model and the thermoindicative tissue phantom were applied for evaluation of a depth of tissue necrosis (DTN) as a result of quasi-cw copper vapor laser (578 nm) irradiation. It has been shown that incident light focusing angle is essential for DTN. In particular, there was a significant rise in DTN parallel to elevation of this angle up to +20 degree(s)C and +5 degree(s)C for both the MC simulation and tissue phantom models, respectively, with no further increase in the necrosis depth above these angles. It is to be noted that the relationship between focusing angles and DTN values was apparently stronger for the real target compared to the MC-derived hypothetical one. To what extent these date are applicable for medical practice can be evaluated in animal models which would simulate laser-assisted therapy for PWS or related dermatologic lesions with converged 578 nm laser beams.

  4. Effect of Pre/Post T6 Heat Treatment on the Mechanical Properties of Laser Welded SSM Cast A356 Aluminium Alloy

    CSIR Research Space (South Africa)

    Akhter, R

    2007-02-01

    Full Text Available h to the alloy A356. During welding, the fusion heat facil- tates the diffusion and the segregation grows, this become less , with a respective drop in the strength and hardness f the metal in the heat affected zone. Due to this effect the e.... von Allmen, Laser Beam Interaction with Metals, Springer-Verlag, Berlin, 1987. ] S. Ramasamy, C.E. Albright, J. Laser Appl. 12 (2000) 101. ] M.L. Santella, T. Engstrom, D. Storjohann, T.Y. Pan, Scripta Mater. 53 (2005) 201–206. ] L. Ivanchev, D...

  5. Rapid assignment of malting barley varieties by matrix-assisted laser desorption-ionisation - Time-of-flight mass spectrometry.

    Science.gov (United States)

    Šedo, Ondrej; Kořán, Michal; Jakešová, Michaela; Mikulíková, Renata; Boháč, Michal; Zdráhal, Zbyněk

    2016-09-01

    A method for discriminating malting barley varieties based on direct matrix-assisted laser desorption-ionisation - time-of-flight mass spectrometry (MALDI-TOF MS) fingerprinting of proteins was developed. Signals corresponding to hordeins were obtained by simple mixing of powdered barley grain with a MALDI matrix solution containing 12.5mgmL(-1) of ferulic acid in an acetonitrile:water:formic acid 50:33:17 v/v/v mixture. Compared to previous attempts at MALDI-TOF mass spectrometric analysis of barley proteins, the extraction and fractionation steps were practically omitted, resulting in a significant reduction in analytical time and costs. The discriminatory power was examined on twenty malting barley varieties and the practicability of the method was tested on sixty barley samples acquired from Pilsner Urquell Brewery. The method is proposed as a rapid tool for variety assignment and purity determination of malting barley that may replace gel electrophoresis currently used for this purpose. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Remodelling of the palatal dome following rapid maxillary expansion (RME): laser scan-quantifications during a low growth period.

    Science.gov (United States)

    Muchitsch, A P; Winsauer, H; Wendl, B; Pichelmayer, M; Kuljuh, E; Szalay, A; Muchitsch, M

    2012-02-01

    To evaluate changes in the palatal vault after rapid maxillary expansion (RME) with bonded splint appliances. The sample comprised 24 children (12 boys and 12 girls) with mixed dentition (mean age 8.3 years; range 6.4-10.4 years). Following expansion, the splint appliance was used as a retainer for 6 months and then removed. Study casts were taken before RME (T0) and when the appliance was removed (T1). Then, 3D laser scans were taken to build complete 3D jaw models. Frontal cross sections were constructed at 53-63, 55-65 and 16-26, exported as coordinates, and finite element calculated to quantify their area, width and height. Maxillary length was also determined. Paired t-tests indicated statistically significant increases in the average palatal width (T1-T0=6.53-6.79 mm) and cross-sectional area (T1-T0=20.39-21.39 mm2) after RME (p0.99 (pmaxillary expansion distinctly increased mean palatal widths and cross-sectional areas. However, palatal height (55-65) and maxillary length decreased to a small extent. © 2012 John Wiley & Sons A/S.

  7. A rapid method for combined laser scanning confocal microscopic and electron microscopic visualization of biocytin or neurobiotin-labeled neurons.

    Science.gov (United States)

    Sun, X J; Tolbert, L P; Hildebrand, J G; Meinertzhagen, I A

    1998-02-01

    Intracellular recording and dye filling are widely used to correlate the morphology of a neuron with its physiology. With laser scanning confocal microscopy, the complex shapes of labeled neurons in three dimensions can be reconstructed rapidly, but this requires fluorescent dyes. These dyes are neither permanent nor electron dense and therefore do not allow investigation by electron microscopy. Here we report a technique that quickly and easily converts a fluorescent label into a more stable and electron-dense stain. With this technique, a neuron is filled with Neurobiotin or biocytin, reacted with fluorophore-conjugated avidin, and imaged by confocal microscopy. To permit long-term storage or EM study, the fluorescent label is then converted to a stable electron-dense material by a single-step conversion using a commercially available ABC kit. We find that the method, which apparently relies on recognition of avidin's excess biotin binding sites by the biotin-peroxidase conjugate, is both faster and less labor intensive than photo-oxidation procedures in common use. The technique is readily adaptable to immunocytochemistry with biotinylated probes, as we demonstrate using anti-serotonin as an example.

  8. Microsoldering and microminiature welding with lasers

    Energy Technology Data Exchange (ETDEWEB)

    Jellison, J.L.; Keicher, D.M.

    1988-01-01

    Miniature welding of electronic and electromechanical components with lasers is a rapidly maturing technology. Extending the use of lasers to microsoldering and microminiature welding applications has also generated moderate interest. Use of lasers for microminiature soldering or welding permits the delivery of accurately controlled amounts of heat to the precise area required. By applying small amounts of heat locally, rework can be accomplished in densely packed circuits without damaging heat sensitive components to conductors. Also, localization of heat obviates the need for using solder alloys of different melting points, which can simplify design. Laser soldering has been applied to conductors ranging from 25 ..mu..m dia. wires to coaxial cables in the 0.3 to 1.25 mm range. For the most part, these conductors were soldered to metallized alumina substrates, although in some instances soft substrates were also used. The potential advantages of microminiature welding have also been explored. 9 refs., 6 figs., 1 tab.

  9. 5 LASER SPOT HEAT TRANSFER ACCOMPANIED BY PARABOLIC TEMPERATURE DISTRIBUTION INSIDE THE ROD

    Directory of Open Access Journals (Sweden)

    Doroshenko Ekaterina Sergeevna

    2013-01-01

    Full Text Available The co-authors have solved the problem of an unsteady temperature field inside a structural beam, if one of its ends is exposed to heating. The problem was solved using a traditional Fourier method. The solution derived by the co-authors was verified by the comparison of the final temperature field and the input data. MathCAD-14 software was employed to make calculations and to generate figures. Application of analytical methods, like Fourier series formalism, in combination with computing aids makes it possible to study both qualitative and quantitative constituents of the process of heat redistribution inside structural units in case of exposure to contingency actions. There will be no uniform temperature reduction in the course of intensive cooling of rod ends after the thermal exposure. If the value of the temperature conductivity coefficient is equal to .01, in 12 hours the residual heating may reach 20 % of the initial heating temperature.

  10. Conduction and Convection of Heat Produced by the Attenuation of Laser Beams in Liquids

    National Research Council Canada - National Science Library

    Goldberg, Irwin S; Garcia, Misty; Maswadi, Saher; Thomas, Robert J; Clark, Clifton D

    2007-01-01

    .... In the second part of the report free-surface effects are considered: These effects include evaporative heat loss and the occurrence of surface tension produced by temperature gradients at the surface...

  11. Effect of heat treatment on mechanical properties and microstructure of selective laser melting 316L stainless steel

    Science.gov (United States)

    Kamariah, M. S. I. N.; Harun, W. S. W.; Khalil, N. Z.; Ahmad, F.; Ismail, M. H.; Sharif, S.

    2017-10-01

    Selective Laser Melting (SLM) has been one of the preferred Additive Manufacturing process to fabricate parts due to its merits in terms of design freedom, lower material waste and faster production when compare to the conventional manufacturing processes. However, due to the thermal gradient experienced during the process, the parts are exposed to the residual stress that leads to parts distortion. This work presents the effect of heat treatments on the micro-hardness of 316L stainless steel parts. In current study, SLM has been employed to fabricate 316L stainless steel compacts. Different heat treatments of 650°C, 950°C, and 1100°C for 2 hours were applied on the compacts. Hardness test were performed on the as-built and heat-treated compacts. The relationship between the microstructures and micro-hardness were discussed in this paper. The results revealed that the micro-hardness of the as-built compacts is between 209.0 and 212.2 HV, which is much higher than the heattreated compacts.

  12. Effect of Heat Treatment on Microstructure and Mechanical Properties of Stellite 12 Fabricated by Laser Additive Manufacturing

    Science.gov (United States)

    Ren, Bo; Zhang, Min; Chen, Changjun; Wang, Xiaonan; Zou, Tao; Hu, Zengrong

    2017-11-01

    Microstructure evolution and wear resistance of Stellite 12 produced by laser additive manufacturing were studied in untreated and heat-treated conditions. In untreated conditions, cobalt matrix dendrites and inter-dendritic eutectic carbides were the primary microstructure, blocky and lamellar eutectic carbides can be found, and M7C3 and M23C6 are the primary carbides. Heat treatment can modify the microstructure of this alloy. Primary carbides were dissolved into the cobalt matrix after solution treatment. Aging treatment resulted in the precipitation of carbides, the transformation of M7C3 into M23C6 carbides, and the increase in microhardness. Solution and aging treatment can also cause the precipitation of carbides, but the morphology and distribution of carbides were absolutely different. The wear resistance of untreated samples at room temperature (RT) and 600 °C is better than that at 200 and 400 °C due to the high hardness at RT and the formation of oxide film at 600 °C. The wear resistance of heat-treated samples was tested at 600 °C; it was dominated by the formation and flake-off of oxide film. The sample that underwent solution plus aging treatment has a superior wear resistance.

  13. Femtosecond fiber laser additive manufacturing of tungsten

    Science.gov (United States)

    Bai, Shuang; Liu, Jian; Yang, Pei; Zhai, Meiyu; Huang, Huan; Yang, Lih-Mei

    2016-04-01

    Additive manufacturing (AM) is promising to produce complex shaped components, including metals and alloys, to meet requirements from different industries such as aerospace, defense and biomedicines. Current laser AM uses CW lasers and very few publications have been reported for using pulsed lasers (esp. ultrafast lasers). In this paper, additive manufacturing of Tungsten materials is investigated by using femtosecond (fs) fiber lasers. Various processing conditions are studied, which leads to desired characteristics in terms of morphology, porosity, hardness, microstructural and mechanical properties of the processed components. Fully dense Tungsten part with refined grain and increased hardness was obtained and compared with parts made with different pulse widths and CW laser. The results are evidenced that the fs laser based AM provides more dimensions to modify mechanical properties with controlled heating, rapid melting and cooling rates compared with a CW or long pulsed laser. This can greatly benefit to the make of complicated structures and materials that could not be achieved before.

  14. Effects of post-heat treatment on microstructure and properties of laser cladded composite coatings on titanium alloy substrate

    Science.gov (United States)

    Li, G. J.; Li, J.; Luo, X.

    2015-01-01

    The composite coatings were produced on the Ti6Al4V alloy substrate by laser cladding. Subsequently, the coatings were heated at 500 °C for 1 h and 2 h and then cooled in air. Effects of post-heat treatment on microstructure, microhardness and fracture toughness of the coatings were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), optical microscopy (OM). Wear resistance of the coatings was evaluated under the dry sliding reciprocating friction condition at room temperature. The results indicated that the coatings mainly consist of a certain amount of coarse white equiaxed WC particles surrounded by the white-bright W2C, a great deal of fine dark spherical TiC particles and the matrix composed of the α(Ti), Ti2Ni and TiNi phases. Effects of the post-heat treatment on phase constituents and microstructure of the coatings were almost negligible due to the low temperature. However, the post-heat treatment could decrease the residual stress and increase fracture toughness of the coatings, and fracture toughness of the coatings was improved from 2.77 MPa m1/2 to 3.80 MPa m1/2 and 4.43 MPa m1/2 with the heat treatment for 1 h and 2 h, respectively. The mutual role would contribute to the reduction in cracking susceptibility. Accompanied with the increase in fracture toughness, microhardness of the coatings was reduced slightly. The dominant wear mechanism for all the coatings was abrasive wear, characterized by micro-cutting or micro-plowing. The heat treatment could significantly decrease the average friction coefficient and reduce the fluctuation of the friction coefficient with the change in sliding time. The appropriate heat treatment time (approximately 1 h) had a minimal effect on wear mass loss and volume loss. Moreover, the improvement in fracture toughness will also be beneficial to wear resistance of the coatings under the long service.

  15. The pulsations of boundary conditions – factor of the rapid wear on heat exchange surfaces in heterogeneous dispersed flows

    Science.gov (United States)

    Khodunkov, V. P.

    2017-11-01

    The results of experimental studies of industrial furnace with a fluidized bed reactor. The data on the values of the coefficient of heat transfer, the quality of fluidization and mixing efficiency. In theory shows that there are significant variables of temperature gradients on the walls of the heat exchange elements are qualitative arguments about the causes of increased wear of heat exchange surfaces in a fluidized bed.

  16. Effect of Heat Treatment on Microstructure and Impact Toughness of Ti-6Al-4V Manufactured by Selective Laser Melting Process

    Directory of Open Access Journals (Sweden)

    Lee K.-A.

    2017-06-01

    Full Text Available This study manufactured Ti-6Al-4V alloy using one of the powder bed fusion 3D-printing processes, selective laser melting, and investigated the effect of heat treatment (650°C/3hrs on microstructure and impact toughness of the material. Initial microstructural observation identified prior-β grain along the building direction before and after heat treatment. In addition, the material formed a fully martensite structure before heat treatment, and after heat treatment, α and β phase were formed simultaneously. Charpy impact tests were conducted. The average impact energy measured as 6.0 J before heat treatment, and after heat treatment, the average impact energy increased by approximately 20% to 7.3 J. Fracture surface observation after the impact test showed that both alloys had brittle characteristics on macro levels, but showed ductile fracture characteristics and dimples at micro levels.

  17. Results of Pulse-Scaling Experiments on Rapid-Growth DKDP Triplers Using the Optical Sciences Laser at 351 nm

    Energy Technology Data Exchange (ETDEWEB)

    Runkel, M; Burnham, A K; Milam, D; Sell, W; Feit, M; Rubenchik, A

    2000-12-11

    Results are reported from recently performed bulk-damage, pulse-scaling experiments on DKDP tripler samples taken from NIF-size, rapid-growth boule BD7. The tests were performed on LLNL's Optical Sciences Laser. A matrix of samples was exposed to single shots at 351 mn (3 {omega}) with average fluences from 4 to 8 J/cm{sup 2} for pulse durations of 1, 3 and 10 ns. The damage sites were scatter-mapped after testing to determine the damage evolution as a function of local beam fluence. The average bulk damage microcavity (pinpoint) density varied nearly linearly with fluence with peak values of approximately 16,000 pp/mm{sup 3} at 1 ns, 10,000 pp/mm{sup 3} at 3 ns and 400 pp/mm{sup 3} at 10 ns for fluences in the 8-10 J/cm{sup 2} range. The average size of a pinpoint was 10(+14,-9) {micro}m at 1 ns, 37 {+-} 20 {micro}m at 3 ns and {approx} 110 {micro}m at 10 ns, although all pulse durations produced pinpoints with a wide distribution of sizes. Analysis of the pinpoint density data yielded pulse-scaling behavior of t{sup 0.35}. Significant planar cracking around the pinpoint as was observed for the 10 ns case but not for the 1 and 3 ns pulses. Crack formation around pinpoints has also been observed frequently for Zeus ADT tests at {approx}8 ns. The high pinpoint densities also lead to significant eruption of near-surface bulk damage. Measurements of the damage site area for surface and bulk gave ratios (A{sub surf}/A{sub bulk}) of 2:1 at 1 ns, 7:1 at 3 ns and 110:1 at 10 ns. Maximum aperture averaged transmission losses on the order 15 percent have been measured by photometry for the worst damage at 1 and 3 ns for beam fluences in the 8-10 J/cm{sup 2} range. Analysis of this data yielded a pulse-scaling behavior of t{sup 0.25} for the obscured area. It was also determined that the crystals used in this test would survive unconditioned exposure to 4 J/cm{sup 2} shots on the NIF laser and still meet the obscuration requirement of 0.1%.

  18. Rapid, high-fluence multi-pass q-switched laser treatment of tattoos with a transparent perfluorodecalin-infused patch: A pilot study.

    Science.gov (United States)

    Biesman, Brian S; O'Neil, Michael P; Costner, Cara

    2015-10-01

    Perfluorodecalin (PFD) has previously been shown to rapidly dissipate the opaque, white micro-bubble layer formed after exposure of tattoos to Q-switched lasers [1]. The current pilot study was conducted to qualitatively determine if the use of a transparent PFD-infused silicone patch would result in more rapid clearance of tattoos than conventional through-air techniques. Black or dark blue tattoos were divided into two halves in a single-site IRB-approved study with 17 subjects with Fitzpatrick skin types I-III. One half of each tattoo served as its own control and was treated with one pass of a standard Q-switched Alexandrite laser (755 nm). The other half of the tattoo was treated directly through a transparent perfluorodecalin (PFD) infused patch (ON Light Sciences, Dublin, CA). The rapid whitening reduction effect of the Patch routinely allowed three to four laser passes in a total of approximately 5 minutes. Both sides were treated at highest tolerated fluence, but the optical clearing, index-matching, and epidermal protection properties of the PFD Patch allowed significantly higher fluence compared to the control side. Standard photographs were taken at baseline, immediately prior to treatment with the PFD Patch in place, and finally before and after each treatment session. Treatments were administered at 4- to 6-week intervals. In a majority of subjects (11 of 17), tattoos treated through a transparent PFD-infused patch showed more rapid tattoo clearance with higher patient and clinician satisfaction than conventional treatment. In no case did the control side fade faster than the PFD Patch side. No unanticipated adverse events were observed. Rapid multi-pass treatment of tattoos with highest tolerated fluence facilitated by a transparent PFD-infused patch clears tattoos more rapidly than conventional methods. © 2015 Wiley Periodicals, Inc.

  19. EFFECT OF THE HEAT AND SURFACE LASER TREATMENT ON THE CORROSION DEGRADATION OF THE Mg-Al ALLOYS

    Directory of Open Access Journals (Sweden)

    Leszek A. Dobrzański

    2011-09-01

    Full Text Available In this paper there is presented the corrosion behavior of the cast magnesium alloys as cast state, after heat and laser treatment. Pitting corrosion resistance of the analyzed alloys was carried out using the potentiodynamic electrochemical method (direct current, based on a anodic polarization curve. On the basis of the achieved anodic polarization curves, using the Tefel extrapolation method near to the corrosion potential, the quantitative data were determined, which describe the electrochemical corrosion process of the investigated alloys: value of the corrosion potential Ecorr (mV, polarization resistance RP (kohm.cm2, corrosion current density icorr (10-6A/cm2, corrosion rate Vcorr (mm/year as well the mass loss Vc (g/m2<.

  20. The Theory of Laser Materials Processing Heat and Mass Transfer in Modern Technology

    CERN Document Server

    Dowden, John

    2009-01-01

    The purpose of the book is to show how general principles can be used to obtain insight into laser processes. The principles used may come from fundamental physical theory or from direct observation of experimental results, but an understanding of the general characteristics of the behaviour of a process is essential for intelligent investigation and implementation, whether the approach is experimental, observational, numerical or analytical. The last two have a special value since the associated costs can be relatively low and may be used as a starting point for more expensive techniques. The construction of simple models whose underlying principles are easy to see is therefore of special value, and an understanding of their strengths and limitations is essential. The applications considered in detail are cutting, keyhole welding, drilling, arc and hybrid laser-arc welding, hardening, cladding, forming and cutting, but the general principles have a very wide application; metallurgical aspects are considered,...

  1. Enhancing nonlinear energy deposition into transparent solids with an elliptically polarized and mid-IR heating laser pulse under two-color femtosecond impact

    Science.gov (United States)

    Potemkin, F. V.; Mareev, E. I.; Bezsudnova, Yu I.; Platonenko, V. T.; Bravy, B. G.; Gordienko, V. M.

    2017-06-01

    We report on an enhancement of deposited energy density of up to 10 kJ cm-3 inside transparent solids (fused silica and quartz) from using two-color µJ energy level tightly focused (NA  =  0.5) co-propagating linearly polarized seeding (visible, 0.62 µm) and elliptically polarized heating (near-IR, 1.24 µm) femtosecond laser pulses. The rise in temperature under constant volume causes pressure of up to 12 GPa. It has been shown experimentally and theoretically that the production of seeding electrons through multiphoton ionization by visible laser pulse paves the way for controllability of the energy deposition and laser-induced micromodification via carrier heating by delayed infrared laser pulses inside the material. The developed theoretical approach predicts that the deposited energy density will be enhanced by up to 14 kJ cm-3 when using longer (up to 5 µm) wavelengths for heating laser pulses inside transparent solids.

  2. Implementation of a practical model for light and heat distribution using laser-induced thermotherapy near to a large vessel

    Energy Technology Data Exchange (ETDEWEB)

    Verhey, J F [Department of Medical Informatics, University of Goettingen, Robert-Koch-Str. 40, D-37075 Goettingen (Germany); Mohammed, Y [Department of Medical Informatics, University of Goettingen, Robert-Koch-Str. 40, D-37075 Goettingen (Germany); Ludwig, A [Department of Craneo-Maxillofacial Surgery, University of Goettingen, Robert-Koch-Str. 40, D-37075 Goettingen (Germany); Giese, K [Department of Medical Informatics, University of Goettingen, Robert-Koch-Str. 40, D-37075 Goettingen (Germany)

    2003-11-07

    This paper introduces a simulation model for light and heat transport in tissues including perfusion effects. The model enables an efficient simulation of the damaged zone induced with an optical fibre for laser interstitial thermotherapy (LITT). It is designed specially for, but not limited to, tissue ablation in the neck region near to vessels. We describe in detail the effects of the rise in temperature caused by the absorption of light in tissue, using the heat equation and including the cooling effects of flow in vessels and of microperfusion in tissue in order to determine the extent of thermal damage. The extent of the necrosis zone is calculated with a damage function at each point of a finite element method (FEM) mesh. The FEM mesh is implemented with FEMLAB 2.3 as an add-on for finite element modelling for Matlab 6.5. LITT for tumour ablation in liver and some other anatomical regions is a well-known and established method (Bundesaerztekammer und Kassenaerztliche Bundesvereinigung 2002 Assessment der Bundesaerztekammer und der Kassenaerztlichen Bundesvereinigung, Koeln). Investigations of treatments using LITT in the neck region are still in progress. We propose a refined model to validate the LITT method in the future in another anatomic region, e.g., in the highly sensitive region of the neck. Our calculations show that in order to induce a lesion with a maximum diameter of about 1 cm near to a large vessel, an application time between 3 and 4 min is needed using a laser power of about 10 W with a Nd:YAG 1064 nm radiation wavelength.

  3. Implementation of a practical model for light and heat distribution using laser-induced thermotherapy near to a large vessel

    Science.gov (United States)

    Verhey, J. F.; Mohammed, Y.; Ludwig, A.; Giese, K.

    2003-11-01

    This paper introduces a simulation model for light and heat transport in tissues including perfusion effects. The model enables an efficient simulation of the damaged zone induced with an optical fibre for laser interstitial thermotherapy (LITT). It is designed specially for, but not limited to, tissue ablation in the neck region near to vessels. We describe in detail the effects of the rise in temperature caused by the absorption of light in tissue, using the heat equation and including the cooling effects of flow in vessels and of microperfusion in tissue in order to determine the extent of thermal damage. The extent of the necrosis zone is calculated with a damage function at each point of a finite element method (FEM) mesh. The FEM mesh is implemented with FEMLAB 2.3 as an add-on for finite element modelling for Matlab 6.5. LITT for tumour ablation in liver and some other anatomical regions is a well-known and established method (Bundesärztekammer und Kassenärztliche Bundesvereinigung 2002 Assessment der Bundesärztekammer und der Kassenärztlichen Bundesvereinigung, Köln). Investigations of treatments using LITT in the neck region are still in progress. We propose a refined model to validate the LITT method in the future in another anatomic region, e.g., in the highly sensitive region of the neck. Our calculations show that in order to induce a lesion with a maximum diameter of about 1 cm near to a large vessel, an application time between 3 and 4 min is needed using a laser power of about 10 W with a Nd:YAG 1064 nm radiation wavelength.

  4. WRNIP1 accumulates at laser light irradiated sites rapidly via its ubiquitin-binding zinc finger domain and independently from its ATPase domain

    Energy Technology Data Exchange (ETDEWEB)

    Nomura, Hironoshin [Molecular Cell Biology Laboratory, Graduate School of Pharmaceutical Sciences, Tohoku University, Aramaki Aoba 6-3, Aobaku, Sendai 980-8578 (Japan); Yoshimura, Akari, E-mail: akari_yo@musashino-u.ac.jp [Research Institute of Pharmaceutical Sciences, Faculty of Pharmacy, Musashino University, 1-1-20 Shinmachi, Nishitokyo-shi, Tokyo 202-8585 (Japan); Edo, Takato [Molecular Cell Biology Laboratory, Graduate School of Pharmaceutical Sciences, Tohoku University, Aramaki Aoba 6-3, Aobaku, Sendai 980-8578 (Japan); Kanno, Shin-ichiro [Division of Dynamic Proteome, Institute of Development, Aging and Cancer, Tohoku University, Seiryomachi 4-1, Aobaku, Sendai 980-8575 (Japan); Tada, Syusuke [Faculty of Pharmaceutical Sciences, Teikyo Heisei University, Ichihara, Chiba 290-0193 (Japan); Seki, Masayuki [Molecular Cell Biology Laboratory, Graduate School of Pharmaceutical Sciences, Tohoku University, Aramaki Aoba 6-3, Aobaku, Sendai 980-8578 (Japan); Yasui, Akira [Division of Dynamic Proteome, Institute of Development, Aging and Cancer, Tohoku University, Seiryomachi 4-1, Aobaku, Sendai 980-8575 (Japan); Enomoto, Takemi [Research Institute of Pharmaceutical Sciences, Faculty of Pharmacy, Musashino University, 1-1-20 Shinmachi, Nishitokyo-shi, Tokyo 202-8585 (Japan)

    2012-01-27

    Highlights: Black-Right-Pointing-Pointer WRNIP1 accumulates in laser light irradiated sites very rapidly via UBZ domain. Black-Right-Pointing-Pointer The ATPase domain of WRNIP1 is dispensable for its accumulation. Black-Right-Pointing-Pointer The accumulation of WRNIP1 seems not to be dependent on the interaction with WRN. -- Abstract: WRNIP1 (Werner helicase-interacting protein 1) was originally identified as a protein that interacts with the Werner syndrome responsible gene product. WRNIP1 contains a ubiquitin-binding zinc-finger (UBZ) domain in the N-terminal region and two leucine zipper motifs in the C-terminal region. In addition, it possesses an ATPase domain in the middle of the molecule and the lysine residues serving as ubiquitin acceptors in the entire of the molecule. Here, we report that WRNIP1 accumulates in laser light irradiated sites very rapidly via its ubiquitin-binding zinc finger domain, which is known to bind polyubiquitin and to be involved in ubiquitination of WRNIP1 itself. The accumulation of WRNIP1 in laser light irradiated sites also required the C-terminal region containing two leucine zippers, which is reportedly involved in the oligomerization of WRNIP1. Mutated WRNIP1 with a deleted ATPase domain or with mutations in lysine residues, which serve as ubiquitin acceptors, accumulated in laser light irradiated sites, suggesting that the ATPase domain of WRNIP1 and ubiquitination of WRNIP1 are dispensable for the accumulation.

  5. Rapid, high‐fluence multi‐pass q‐switched laser treatment of tattoos with a transparent perfluorodecalin‐infused patch: A pilot study

    Science.gov (United States)

    O'Neil, Michael P.; Costner, Cara

    2015-01-01

    Background and Objectives Perfluorodecalin (PFD) has previously been shown to rapidly dissipate the opaque, white micro‐bubble layer formed after exposure of tattoos to Q‐switched lasers [1]. The current pilot study was conducted to qualitatively determine if the use of a transparent PFD‐infused silicone patch would result in more rapid clearance of tattoos than conventional through‐air techniques. Materials and Methods Black or dark blue tattoos were divided into two halves in a single‐site IRB‐approved study with 17 subjects with Fitzpatrick skin types I–III. One half of each tattoo served as its own control and was treated with one pass of a standard Q‐switched Alexandrite laser (755 nm). The other half of the tattoo was treated directly through a transparent perfluorodecalin (PFD) infused patch (ON Light Sciences, Dublin, CA). The rapid whitening reduction effect of the Patch routinely allowed three to four laser passes in a total of approximately 5 minutes. Both sides were treated at highest tolerated fluence, but the optical clearing, index‐matching, and epidermal protection properties of the PFD Patch allowed significantly higher fluence compared to the control side. Standard photographs were taken at baseline, immediately prior to treatment with the PFD Patch in place, and finally before and after each treatment session. Treatments were administered at 4‐ to 6‐week intervals. Results In a majority of subjects (11 of 17), tattoos treated through a transparent PFD‐infused patch showed more rapid tattoo clearance with higher patient and clinician satisfaction than conventional treatment. In no case did the control side fade faster than the PFD Patch side. No unanticipated adverse events were observed. Conclusions Rapid multi‐pass treatment of tattoos with highest tolerated fluence facilitated by a transparent PFD‐infused patch clears tattoos more rapidly than conventional methods. Lasers Surg. Med. 47:613–618, 2015. © 2015 The

  6. Rapid Identification of the Foodborne Pathogen Trichinella spp. by Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry.

    Science.gov (United States)

    Mayer-Scholl, Anne; Murugaiyan, Jayaseelan; Neumann, Jennifer; Bahn, Peter; Reckinger, Sabine; Nöckler, Karsten

    2016-01-01

    Human trichinellosis occurs through consumption of raw or inadequately processed meat or meat products containing larvae of the parasitic nematodes of the genus Trichinella. Currently, nine species and three genotypes are recognized, of which T. spiralis, T. britovi and T. pseudospiralis have the highest public health relevance. To date, the differentiation of the larvae to the species and genotype level is based primarily on molecular methods, which can be relatively time consuming and labor intensive. Due to its rapidness and ease of use a matrix assisted laser desorption / ionization time of flight mass spectrometry (MALDI-TOF MS) reference spectra database using Trichinella strains of all known species and genotypes was created. A formicacid/acetonitrile protein extraction was carried out after pooling 10 larvae of each Trichinella species and genotype. Each sample was spotted 9 times using α-cyano 4-hydoxy cinnamic acid matrix and a MicroFlex LT mass spectrometer was used to acquire 3 spectra (m/z 2000 to 20000 Da) from each spot resulting in 27 spectra/species or genotype. Following the spectra quality assessment, Biotyper software was used to create a main spectra library (MSP) representing nine species and three genotypes of Trichinella. The evaluation of the spectra generated by MALDI-TOF MS revealed a classification which was comparable to the results obtained by molecular methods. Also, each Trichinella species utilized in this study was distinct and distinguishable with a high confidence level. Further, different conservation methods such as freezing and conservation in alcohol and the host species origin of the isolated larvae did not have a significant influence on the generated spectra. Therefore, the described MALDI-TOF MS can successfully be implemented for both genus and species level identification and represents a major step forward in the use of this technique in foodborne parasitology.

  7. Rapid Identification of the Foodborne Pathogen Trichinella spp. by Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry.

    Directory of Open Access Journals (Sweden)

    Anne Mayer-Scholl

    Full Text Available Human trichinellosis occurs through consumption of raw or inadequately processed meat or meat products containing larvae of the parasitic nematodes of the genus Trichinella. Currently, nine species and three genotypes are recognized, of which T. spiralis, T. britovi and T. pseudospiralis have the highest public health relevance. To date, the differentiation of the larvae to the species and genotype level is based primarily on molecular methods, which can be relatively time consuming and labor intensive. Due to its rapidness and ease of use a matrix assisted laser desorption / ionization time of flight mass spectrometry (MALDI-TOF MS reference spectra database using Trichinella strains of all known species and genotypes was created. A formicacid/acetonitrile protein extraction was carried out after pooling 10 larvae of each Trichinella species and genotype. Each sample was spotted 9 times using α-cyano 4-hydoxy cinnamic acid matrix and a MicroFlex LT mass spectrometer was used to acquire 3 spectra (m/z 2000 to 20000 Da from each spot resulting in 27 spectra/species or genotype. Following the spectra quality assessment, Biotyper software was used to create a main spectra library (MSP representing nine species and three genotypes of Trichinella. The evaluation of the spectra generated by MALDI-TOF MS revealed a classification which was comparable to the results obtained by molecular methods. Also, each Trichinella species utilized in this study was distinct and distinguishable with a high confidence level. Further, different conservation methods such as freezing and conservation in alcohol and the host species origin of the isolated larvae did not have a significant influence on the generated spectra. Therefore, the described MALDI-TOF MS can successfully be implemented for both genus and species level identification and represents a major step forward in the use of this technique in foodborne parasitology.

  8. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for rapid identification of fungal rhinosinusitis pathogens.

    Science.gov (United States)

    Huang, Yanfei; Wang, Jinglin; Zhang, Mingxin; Zhu, Min; Wang, Mei; Sun, Yufeng; Gu, Haitong; Cao, Jingjing; Li, Xue; Zhang, Shaoya; Lu, Xinxin

    2017-03-01

    Filamentous fungi are among the most important pathogens, causing fungal rhinosinusitis (FRS). Current laboratory diagnosis of FRS pathogens mainly relies on phenotypic identification by culture and microscopic examination, which is time consuming and expertise dependent. Although matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) MS has been employed to identify various fungi, its efficacy in the identification of FRS fungi is less clear. A total of 153 FRS isolates obtained from patients were analysed at the Clinical Laboratory at the Beijing Tongren Hospital affiliated to the Capital Medical University, between January 2014 and December 2015. They were identified by traditional phenotypic methods and Bruker MALDI-TOF MS (Bruker, Biotyper version 3.1), respectively. Discrepancies between the two methods were further validated by sequencing. Among the 153 isolates, 151 had correct species identification using MALDI-TOF MS (Bruker, Biot 3.1, score ≥2.0 or 2.3). MALDI-TOF MS enabled identification of some very closely related species that were indistinguishable by conventional phenotypic methods, including 1/10 Aspergillus versicolor, 3/20 Aspergillus flavus, 2/30 Aspergillus fumigatus and 1/20 Aspergillus terreus, which were misidentified by conventional phenotypic methods as Aspergillus nidulans, Aspergillus oryzae, Aspergillus japonicus and Aspergillus nidulans, respectively. In addition, 2/2 Rhizopus oryzae and 1/1 Rhizopus stolonifer that were identified only to the genus level by the phenotypic method were correctly identified by MALDI-TOF MS. MALDI-TOF MS is a rapid and accurate technique, and could replace the conventional phenotypic method for routine identification of FRS fungi in clinical microbiology laboratories.

  9. The influence of heat treatment and process parameters optimization on hardness and corrosion properties of laser alloyed X12CrNiMo steel

    CSIR Research Space (South Africa)

    Popoola, API

    2016-10-01

    Full Text Available Martensitic stainless steels are used in the production of steam turbine blades but their application is limited due to low hardness and poor corrosion resistance. Laser surface alloying and heat treatment of X12CrNiMo Martensitic stainless steel...

  10. High temperature heat source generation with quasi-continuous wave semiconductor lasers at power levels of 6 W for medical use.

    Science.gov (United States)

    Fujimoto, Takahiro; Imai, Yusuke; Tei, Kazuyoku; Ito, Shinobu; Kanazawa, Hideko; Yamaguchi, Shigeru

    2014-01-01

    We investigate a technology to create a high temperature heat source on the tip surface of the glass fiber proposed for medical surgery applications. Using 4 to 6 W power level semiconductor lasers at a wavelength of 980 nm, a laser coupled fiber tip was preprocessed to contain a certain amount of titanium oxide powder with a depth of 100 μm from the tip surface so that the irradiated low laser energy could be perfectly absorbed to be transferred to thermal energy. Thus, the laser treatment can be performed without suffering from any optical characteristic of the material. A semiconductor laser was operated quasi-continuous wave mode pulse time duration of 180 ms and >95% of the laser energy was converted to thermal energy in the fiber tip. Based on two-color thermometry, by using a gated optical multichannel analyzer with a 0.25 m spectrometer in visible wavelength region, the temperature of the fiber tip was analyzed. The temperature of the heat source was measured to be in excess 3100 K.

  11. Influence of the gaseous form on the precursor heating layer of a laser-supported detonation wave using half self-emission half shadowgraph visualization

    Science.gov (United States)

    Shimamura, Kohei; Michigami, Keisuke; Ofoso, Joseph; Komursaki, Kimiya

    2012-10-01

    After breakdown one of the possible mechanisms of occurrence of laser-produced plasma is noted as laser-supported detonation (LSD) wave. This wave consisting of the shock wave and the beam absorbing plasma travels at 1-10 km/s along the beam channel in the direction opposite to the laser incidence. The laser heating structure is recognized as the ZND model of chemical detonation. However, Shimamura et. al, showed that the plasma proceeds the shock wave during LSD regime. The role of shock compression is relatively smaller than preheating by laser. The conventional model is inconsistent with our paper. To investigate the heating structure of a LSD wave, half self-emission half shadowgraph (HSHS) methods provides the self-emission image from the plasma on the top half and the shadowgraph image of the induced shock wave on the bottom half simultaneously. A TEA CO2 laser was used at 10 J incident energy. The locations of both wave fronts were detected from the brightness distribution of the HSHS images. As a result, the propagation of ionization front precedes that of shock wave front by the order of 10-4 m in air and N2. Preheating layer of N2 is shorter than that of air because O2 in air has the lowest ionization energy. Thus, a characteristic of preionization layer depends on the ionization properties because photoionization by the UV radiation generate the seed electrons ahead of shock wave.

  12. Laser-Induced Chemical Vapour Deposition of Silicon Carbonitride

    OpenAIRE

    Besling, W.; van der Put, P.; Schoonman, J.

    1995-01-01

    Laser-induced Chemical Vapour Deposition of silicon carbonitride coatings and powders has been investigated using hexamethyldisilazane (HMDS) and ammonia as reactants. An industrial CW CO2-laser in parallel configuration has been used to heat up the reactant gases. HMDS dissociates in the laser beam and reactive radicals are formed which increase rapidly in molecular weight by an addition mechanism. Dense polymer-like silicon carbonitride thin films and nanosized powders are formed depending ...

  13. Targeted gene expression without a tissue-specific promoter: creating mosaic embryos using laser-induced single-cell heat shock

    Science.gov (United States)

    Halfon, M. S.; Kose, H.; Chiba, A.; Keshishian, H.

    1997-01-01

    We have developed a method to target gene expression in the Drosophila embryo to a specific cell without having a promoter that directs expression in that particular cell. Using a digitally enhanced imaging system to identify single cells within the living embryo, we apply a heat shock to each cell individually by using a laser microbeam. A 1- to 2-min laser treatment is sufficient to induce a heat-shock response but is not lethal to the heat-shocked cells. Induction of heat shock was measured in a variety of cell types, including neurons and somatic muscles, by the expression of beta-galactosidase from an hsp26-lacZ reporter construct or by expression of a UAS target gene after induction of hsGAL4. We discuss the applicability of this technique to ectopic gene expression studies, lineage tracing, gene inactivation studies, and studies of cells in vitro. Laser heat shock is a versatile technique that can be adapted for use in a variety of research organisms and is useful for any studies in which it is desirable to express a given gene in only a distinct cell or clone of cells, either transiently or constitutively, at a time point of choice.

  14. Effect of Heat Treatment on Microstructure and Mechanical Properties of Laser Additively Manufactured AISI H13 Tool Steel

    Science.gov (United States)

    Chen, ChangJun; Yan, Kai; Qin, Lanlan; Zhang, Min; Wang, Xiaonan; Zou, Tao; Hu, Zengrong

    2017-11-01

    The effect of heat treatment on microstructure and mechanical properties (microhardness, wear resistance and impact toughness) of laser additively manufactured AISI H13 tool steel was systemically investigated. To understand the variation of microstructure and mechanical properties under different heat treatments, the as-deposited samples were treated at 350, 450, 550, 600 and 650 °C/2 h, respectively. Microstructure and phase transformation were investigated through optical microscopy, scanning electron microscope and transmission electron microscope. The mechanical properties were characterized by nanoindentation tests, Charpy tests and high-temperature wear tests. The microstructure of as-deposited samples consisted of martensite, ultrafine carbides and retained austenite. After the tempering treatment, the martensite was converted into tempered martensite and some fine alloy carbides which precipitated in the matrix. When treated at 550 °C, the greatest hardness and nanohardness were 600 HV0.3 and 6119.4 MPa due to many needle-like carbides precipitation. The value of hardness increased firstly and then decreased when increasing the temperature. When tempered temperatures exceeded 550 °C, the carbides became coarse, and martensitic matrix recrystallized at the temperature of 650 °C. The least impact energy was 6.0 J at a temperature of 550 °C. Samples tempered at 550 °C had larger wear volume loss than that of others. Wear resistances of all samples under atmospheric condition at 400 °C showed an oxidation mechanism.

  15. Lasers.

    Science.gov (United States)

    Passeron, T

    2012-12-01

    Lasers are a very effective approach for treating many hyperpigmented lesions. They are the gold standard treatment for actinic lentigos and dermal hypermelanocytosis, such as Ota nevus. Becker nevus, hyperpigmented mosaicisms, and lentigines can also be successfully treated with lasers, but they could be less effective and relapses can be observed. However, lasers cannot be proposed for all types of hyperpigmentation. Thus, freckles and café-au-lait macules should not be treated as the relapses are nearly constant. Due to its complex pathophysiology, melasma has a special place in hyperpigmented dermatoses. Q-switched lasers (using standard parameters or low fluency) should not be used because of consistent relapses and the high risk of post-inflammatory hyperpigmentation. Paradoxically, targeting the vascular component of the melasma lesion with lasers could have a beneficial effect. However, these results have yet to be confirmed. In all cases, a precise diagnosis of the type of hyperpigmentation is mandatory before any laser treatment, and the limits and the potential side effects of the treatment must be clearly explained to patients. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

  16. [Lasers].

    Science.gov (United States)

    Passeron, T

    2012-11-01

    Lasers are a very effective approach for treating many hyperpigmented lesions. They are the gold standard treatment for actinic lentigos and dermal hypermelanocytosis, such as Ota nevus. Becker nevus, hyperpigmented mosaicisms, and lentigines can also be successfully treated with lasers, but they could be less effective and relapses can be observed. However, lasers cannot be proposed for all types of hyperpigmentation. Thus, freckles and café-au-lait macules should not be treated as the relapses are nearly constant. Due to its complex pathophysiology, melasma has a special place in hyperpigmented dermatoses. Q-switched lasers (using standard parameters or low fluency) should not be used because of consistent relapses and the high risk of post-inflammatory hyperpigmentation. Paradoxically, targeting the vascular component of the melasma lesion with lasers could have a beneficial effect. However, these results have yet to be confirmed. In all cases, a precise diagnosis of the type of hyperpigmentation is mandatory before any laser treatment, and the limits and the potential side effects of the treatment must be clearly explained to patients. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

  17. [Study of the effect of heat source separation distance on plasma physical properties in laser-pulsed GMAW hybrid welding based on spectral diagnosis technique].

    Science.gov (United States)

    Liao, Wei; Hua, Xue-Ming; Zhang, Wang; Li, Fang

    2014-05-01

    In the present paper, the authors calculated the plasma's peak electron temperatures under different heat source separation distance in laser- pulse GMAW hybrid welding based on Boltzmann spectrometry. Plasma's peak electron densities under the corresponding conditions were also calculated by using the Stark width of the plasma spectrum. Combined with high-speed photography, the effect of heat source separation distance on electron temperature and electron density was studied. The results show that with the increase in heat source separation distance, the electron temperatures and electron densities of laser plasma did not changed significantly. However, the electron temperatures of are plasma decreased, and the electron densities of are plasma first increased and then decreased.

  18. New developments in laser-heated diamond anvil cell with in situ synchrotron x-ray diffraction at High Pressure Collaborative Access Team.

    Science.gov (United States)

    Meng, Yue; Hrubiak, Rostislav; Rod, Eric; Boehler, Reinhard; Shen, Guoyin

    2015-07-01

    An overview of the in situ laser heating system at the High Pressure Collaborative Access Team, with emphasis on newly developed capabilities, is presented. Since its establishment at the beamline 16-ID-B a decade ago, laser-heated diamond anvil cell coupled with in situ synchrotron x-ray diffraction has been widely used for studying the structural properties of materials under simultaneous high pressure and high temperature conditions. Recent developments in both continuous-wave and modulated heating techniques have been focusing on resolving technical issues of the most challenging research areas. The new capabilities have demonstrated clear benefits and provide new opportunities in research areas including high-pressure melting, pressure-temperature-volume equations of state, chemical reaction, and time resolved studies.

  19. C-fiber-related EEG-oscillations induced by laser radiant heat stimulation of capsaicin-treated skin

    Directory of Open Access Journals (Sweden)

    Claudia Domnick

    2009-03-01

    Full Text Available Claudia Domnick1, Michael Hauck1,2,3, Kenneth L Casey3, Andreas K Engel1, Jürgen Lorenz1,3,41Department of Neurophysiology and Pathophysiology; 2Department of Neurology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; 3Department of Neurology, University of Michigan, Ann Arbor, MI, USA; 4Faculty of Life Sciences, Hamburg University of Applied Sciences, Hamburg, GermanyAbstract: Nociceptive input reaches the brain via two different types of nerve fibers, moderately fast A-delta and slowly conducting C-fibers, respectively. To explore their distinct roles in normal and inflammatory pain we used laser stimulation of normal and capsaicin treated skin at proximal and distal arm sites in combination with time frequency transformation of electroencephalography (EEG data. Comparison of phase-locked (evoked and non-phase-locked (total EEG to laser stimuli revealed three significant pain-related oscillatory responses. First, an evoked response in the delta-theta band, mediated by A-fibers, was reduced by topical capsaicin treatment. Second, a decrease of total power in the alpha-to-gamma band reflected both an A- and C-nociceptor-mediated response with only the latter being reduced by capsaicin treatment. Finally, an enhancement of total power in the upper beta band was mediated exclusively by C-nociceptors and appeared strongly augmented by capsaicin treatment. These findings suggest that phase-locking of brain activity to stimulus onset is a critical feature of A-delta nociceptive input, allowing rapid orientation to salient and potentially threatening events. In contrast, the subsequent C-nociceptive input exhibits clearly less phase coupling to the stimulus. It may primarily signal the tissue status allowing more long-term behavioral adaptations during ongoing inflammatory events that accompany tissue damage.Keywords: C-fibers, oscillations, EEG, laser, capsaicin, inflammatory pain

  20. Erbium Distribution in Single Crystal YAG Fibers Grown by Laser-Heated Pedestal Growth Technique

    Science.gov (United States)

    2015-08-28

    Standard Form 298 (Rev 8/98) Prescribed by ANSI Std. Z39.18 732-445-3932 W911NF-12-1-0536 62114- PH -HEL.7 Conference Proceeding a. REPORT 14...collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. Rutgers, The...the growth, a PID feedback loop monitors the diameter of the fiber. The laser micrometer reads the instantaneous diameter of the fiber and this is

  1. Fast heating of fuel assembled in a spherical deuterated polystyrene shell target by counter-irradiating tailored laser pulses delivered by a HAMA 1 Hz ICF driver

    Science.gov (United States)

    Mori, Y.; Nishimura, Y.; Hanayama, R.; Nakayama, S.; Ishii, K.; Kitagawa, Y.; Sekine, T.; Takeuchi, Y.; Kurita, T.; Satoh, N.; Kawashima, T.; Komeda, O.; Nishi, T.; Azuma, H.; Hioki, T.; Motohiro, T.; Sunahara, A.; Sentoku, Y.; Miura, E.

    2017-11-01

    Fast heating is a method of heating an assembled high-density plasma into a hot state by irradiating it with short-duration (sub-picosecond), high-intensity (> 1018 W cm-2 ) laser pulses before the plasma expands and dissolves hydrodynamically. In this paper, we present detailed experimental results of fast heating fuel assembled in a spherical deuterated polystyrene shell target of 500 μ m diameter and 7 μm thickness with counterbeam illumination by using a HAMA 1 Hz, 5.9 J inertial confinement fusion laser driver with pulse tailoring. These tailored pulses contain three pulses in sequence: a ‘foot’ pulse of 2.4 J/25 ns, a ‘spike’ pulse of 0.5 J/300 ps and a ‘heater’ pulse of 0.4 J/110 fs; these pulses are designed to assemble the fuel and heat it. By varying the energy of the foot pulse, we find that fast heating the fuel is achieved only if the fuel is weakly ablated by the foot pulse and then shock-assembled by the spike pulse into the target centre so that the heater pulse can access the fuel with a focal intensity greater than 1018 W cm-2 . Without a foot pulse, the heater pulse contributes to assembling the fuel. For higher foot-pulse energies, the heater pulse drives a hydrodynamic motion with speeds of the order 107 cm s-1 with intensities of the order 1017 W cm-2 , resulting in re-assembling and additional heating of the pre-assembled fuel. Once a shock-assembled core is achieved at the target centre, we succeed qualitatively in fast heating the core for shots in sequence with variations of laser energy within 18%. The coupling efficiency from the heating laser to the core is inferred to be (10 +/- 2) % in total: (8 +/- 1.6) % for the ionized bulk electrons and (2 +/- 0.4) % for the bulk ions. The fusion neutron spectrum detected on the laser axis exhibits peaks at 1.0 MeV, 1.7 MeV and 3.8 MeV. These peaks are attributed to the C(d, n){\\hspace{0pt}}13 N and d(d, n){\\hspace{0pt}}3 He reactions induced by counterpropagating fast deuterons

  2. Rapid bonding and easy debonding of orthodontic appliances with 4-META/MMA-TBB resin using thermal heating.

    Science.gov (United States)

    Kameda, Takashi; Ohkuma, Kazuo; Terada, Kazuto

    2014-01-01

    4-Methacryloyloxyethyl trimellitate anhydride/methyl methacrylate-tri-n-butylborane (4-META/MMA-TBB) resin is widely used as a direct bonding adhesive for orthodontic appliances because of its strong bonding ability. However, its clinical disadvantages include long setting times and difficult debonding with subsequent residual adhesive left on the enamel surface. To resolve these problems, thermal heating was applied to orthodontic appliances. The setting time was dramatically reduced by thermal heating (160°C for 5 s), with the shear bond strength remaining the same as that stated in the manufacturer's instructions. Debonding of appliances following thermal heating (160°C for 20 s) could be easily performed, decreasing the amount of adhesive left on enamel. These conditions were not accompanied by an increase in the heat pain threshold of pulpal dentin. These results suggest that the use of thermal heating in the bonding/debonding of 4-META/MMA-TBB resin may resolve its clinical weaknesses, making its ease of use similar to light-cured resin.

  3. Effect of Homogenizing Heat Treatment of Liquid Aluminum-Copper Alloys on the Structure of Rapidly Crystallized Specimens

    Science.gov (United States)

    Astaf'ev, V. V.; Kurochkin, A. R.; Yablonskikh, T. I.; Brodova, I. G.; Popel', P. S.

    2017-11-01

    Centrifugal casting into a massive slot chill mold was used to prepare two series of specimens of alloys of the Al - Cu system, containing from 10 to 32.2 at.% Cu. The first series was fabricated without a homogenizing heat treatment of the melt, while the second series was fabricated with heating of the melt to 1400°C. Both kinds of specimens were cast at the same temperature in order to provide for the same cooling rate of about 104 K/sec. The structures, phase compositions and microhardnesses of the structural components are compared. It is established that the homogenizing heat treatment changes the kinetics of crystallization and, hence, the proportion of phases in the alloy structure and the copper content in them.

  4. Effects of blue diode laser (445 nm) and LED (430-480 nm) radiant heat treatments on dental glass ionomer restoratives

    Science.gov (United States)

    Dionysopoulos, Dimitrios; Tolidis, Kosmas; Strakas, Dimitrios; Gerasimou, Paris; Sfeikos, Thrasyvoulos; Gutknecht, Norbert

    2018-02-01

    The purpose of this in vitro study was to evaluate the effect of two radiant heat treatments on water sorption, solubility and surface roughness of three conventional glass ionomer cements by using a blue diode laser (445 nm) and a light emitting diode (LED) unit (430-480 nm). Thirty disk-shaped specimens were prepared for each tested GIC (Equia Fil, Ketac Universal Aplicap and Riva Self Cure). The experimental groups (n = 10) of the study were as follows: Group 1 was the control group, in Group 2 the specimens were irradiated for 60 s at the top surface using a LED light-curing unit and in Group 3 the specimens were irradiated for 60 s at the top surface using a blue light diode laser. Statistical analysis was performed using one-way ANOVA and Tukey post hoc tests at a level of significance of a = 0.05. Radiant heat treatments with both laser and LED devices significantly decreased water sorption and solubility (p 0.05). Among the tested materials there were differences in water sorption and solubility (p 0.05). The use of the blue diode laser for this radiant heat treatment was harmless for the surface of the tested GICs and may be advantageous for the longevity of their restorations.

  5. Evaluation of repetitive-PCR and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) for rapid strain typing of Bacillus coagulans.

    Science.gov (United States)

    Sato, Jun; Nakayama, Motokazu; Tomita, Ayumi; Sonoda, Takumi; Hasumi, Motomitsu; Miyamoto, Takahisa

    2017-01-01

    In order to establish rapid and accurate typing method for Bacillus coagulans strains which is important for controlling in some canned foods and tea-based beverages manufacturing because of the high-heat resistance of the spores and high tolerance of the vegetative cells to catechins and chemicals, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and repetitive-PCR (rep-PCR) were evaluated. For this purpose, 28 strains of B. coagulans obtained from various culture collections were tested. DNA sequence analyses of the genes encoding 16S rRNA and DNA gyrase classified the test strains into two and three groups, respectively, regardless of their phenotypes. Both MALDI-TOF MS and rep-PCR methods classified the test strains in great detail. Strains classified in each group showed similar phenotypes, such as carbohydrate utilization determined using API 50CH. In particular, the respective two pairs of strains which showed the same metabolic characteristic were classified into the same group by both MALDI-TOF MS and rep-PCR methods separating from the other strains. On the other hand, the other strains which have the different profiles of carbohydrate utilization were separated into different groups by these methods. These results suggested that the combination of MALDI-TOF MS and rep-PCR analyses was advantageous for the rapid and detailed typing of bacterial strains in respect to both phenotype and genotype.

  6. Evaluation of repetitive-PCR and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS for rapid strain typing of Bacillus coagulans.

    Directory of Open Access Journals (Sweden)

    Jun Sato

    Full Text Available In order to establish rapid and accurate typing method for Bacillus coagulans strains which is important for controlling in some canned foods and tea-based beverages manufacturing because of the high-heat resistance of the spores and high tolerance of the vegetative cells to catechins and chemicals, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS and repetitive-PCR (rep-PCR were evaluated. For this purpose, 28 strains of B. coagulans obtained from various culture collections were tested. DNA sequence analyses of the genes encoding 16S rRNA and DNA gyrase classified the test strains into two and three groups, respectively, regardless of their phenotypes. Both MALDI-TOF MS and rep-PCR methods classified the test strains in great detail. Strains classified in each group showed similar phenotypes, such as carbohydrate utilization determined using API 50CH. In particular, the respective two pairs of strains which showed the same metabolic characteristic were classified into the same group by both MALDI-TOF MS and rep-PCR methods separating from the other strains. On the other hand, the other strains which have the different profiles of carbohydrate utilization were separated into different groups by these methods. These results suggested that the combination of MALDI-TOF MS and rep-PCR analyses was advantageous for the rapid and detailed typing of bacterial strains in respect to both phenotype and genotype.

  7. Space Launch System Base Heating Test: Tunable Diode Laser Absorption Spectroscopy

    Science.gov (United States)

    Parker, Ron; Carr, Zak; MacLean, Mathew; Dufrene, Aaron; Mehta, Manish

    2016-01-01

    This paper describes the Tunable Diode Laser Absorption Spectroscopy (TDLAS) measurement of several water transitions that were interrogated during a hot-fire testing of the Space Launch Systems (SLS) sub-scale vehicle installed in LENS II. The temperature of the recirculating gas flow over the base plate was found to increase with altitude and is consistent with CFD results. It was also observed that the gas above the base plate has significant velocity along the optical path of the sensor at the higher altitudes. The line-by-line analysis of the H2O absorption features must include the effects of the Doppler shift phenomena particularly at high altitude. The TDLAS experimental measurements and the analysis procedure which incorporates the velocity dependent flow will be described.

  8. CO2-laser micromachining and back-end processing for rapid production of PMMA-based microfluidic systems

    DEFF Research Database (Denmark)

    Klank, Henning; Kutter, Jörg Peter; Geschke, Oliver

    2002-01-01

    , a three-layer polymer microstructure with included optical fibers was fabricated within two days. The use of CO2-laser systems to produce microfluidic systems has not been published before. These systems provide a cost effective alternative to UV-laser systems and they are especially useful...... for microstructured PMMA [poly( methyl methacrylate)] parts were investigated, such as solvent-assisted glueing, melting, laminating and surface activation using a plasma asher. A solvent-assisted thermal bonding method proved to be the most time-efficient one. Using laser micromachining together with bonding...

  9. Rapid long-wave infrared laser-induced breakdown spectroscopy measurements using a mercury-cadmium-telluride linear array detection system.

    Science.gov (United States)

    Yang, Clayton S-C; Brown, Eiei; Kumi-Barimah, Eric; Hommerich, Uwe; Jin, Feng; Jia, Yingqing; Trivedi, Sudhir; D'souza, Arvind I; Decuir, Eric A; Wijewarnasuriya, Priyalal S; Samuels, Alan C

    2015-11-20

    In this work, we develop a mercury-cadmium-telluride linear array detection system that is capable of rapidly capturing (∼1-5  s) a broad spectrum of atomic and molecular laser-induced breakdown spectroscopy (LIBS) emissions in the long-wave infrared (LWIR) region (∼5.6-10  μm). Similar to the conventional UV-Vis LIBS, a broadband emission spectrum of condensed phase samples covering the whole 5.6-10 μm region can be acquired from just a single laser-induced microplasma or averaging a few single laser-induced microplasmas. Atomic and molecular signature emission spectra of solid inorganic and organic tablets and thin liquid films deposited on a rough asphalt surface are observed. This setup is capable of rapidly probing samples "as is" without the need of elaborate sample preparation and also offers the possibility of a simultaneous UV-Vis and LWIR LIBS measurement.

  10. Computer modeling of the optical properties and heating of spherical gold and silica-gold nanoparticles for laser combined imaging and photothermal treatment.

    Science.gov (United States)

    Pustovalov, V; Astafyeva, L; Jean, B

    2009-06-03

    Recently, several groups of investigators (Anderson, Halas, Zharov, El-Sayed and their co-workers (Pitsillides et al 2003 Biophys. J. 84 4023-31, Zharov et al 2003 Appl. Phys. Lett. 83 4897-9, Zharov et al 2004 Proc. SPIE 5319 291-9, Loo et al 2005 Nano Lett. 5 709-11, Gobin et al 2007 Nano Lett. 7 1929-34, Fu et al 2008 Nanotechnology 19 045103, Huang et al 2006 J. Am. Chem. Soc. 128 2115-20, Jain et al 2006 J. Phys. Chem. B 110 7238-48, Jain et al 2007 Nano Today 2 18-29)) demonstrated, through pioneering results, the great potential of laser thermal therapy of cells and tissues conjugated with gold nanoparticles. It was also proposed to use combined diagnostics and therapy on the basis of nanoparticle selection for achievement of efficient contrast for laser imaging applications, as well as for photothermal therapy. However, the current understanding of the relationship between optical properties (absorption, backscattering) of nanoparticles, the efficiency of nanoparticle heating and the possibility to use them for combined imaging and therapy is limited. Here, we report the results of computer modeling of optical absorption and backscattering properties and laser heating of gold and silica-gold spherical nanoparticles for laser combined imaging and photothermal treatment of cells and tissues conjugated with nanoparticles. The efficiencies of nanoparticle heating and backscattering by nanoparticles, depending upon their radii, structure and optical properties of the metal, were investigated. This paper focuses on the analysis and determination of appropriate ranges of nanoparticle sizes for the purposes of laser combined imaging and photothermal treatment. The possibility to use spherical gold and silica-gold nanoparticles in determined ranges of radii for these purposes for laser wavelengths 532 and 800 nm is investigated.

  11. TEM Characterization and Properties of Cu-1 wt.% TiB2 Nanocomposite Prepared by Rapid Solidification and Subsequent Heat Treatment

    Directory of Open Access Journals (Sweden)

    M. Sobhani

    2012-12-01

    Full Text Available Copper matrix composite reinforced by 1wt.% TiB2 particles was prepared using in situ reaction of Cu-1.4wt.% Ti and Cu-0.7wt.% B by rapid solidification and subsequent heat treatment for 1-20 hrs at 900ºC. High-resolution transmission electron microscopy (HRTEM characterization showed that primary TiB2 particles were formed in liquid copper. Heat treatment of as-solidified samples led to the formation of secondary TiB2 particles via spinodal decomposition of titanium-rich zone inside the grains. Mechanical properties (after 50% reduction in area as well as electrical conductivity of composite were evaluated after heat treatment and were compared with those of pure copper. The results indicated that, due to the formation of secondary TiB2 particles in the matrix, electrical conductivity increased along with hardness up to 10 hrs of heat treatment and reached 65% IACS and 155 HV, respectively. Moreover, the maximum ultimate (i.e. 580 MPa and yield (i.e. 555 MPa strengths of composite were achieved at this time.

  12. Basic Research Investigations into Multimode Laser and EM Launchers for Affordable, Rapid Access to Space (Volumes 1 and 2)

    Science.gov (United States)

    2010-08-31

    kinetics, ray tracing, laser absorption and refraction by plasma, nonequilibrium plasma radiation, and plasma resonance. His code results have been...placed inside the HST test section, just downstream of the 2D Lightcraft model (Scientech Astral Series S, 200 mm aperture) to capture the actual...laser pulse energy from the TEA-620 ’s is measured by two thermopile calorimeters: Gentec UP60N-40S-H9, and Scientec Astral 360801S. Both TEA-620

  13. Characteristics of the calibration curves of copper for the rapid sorting of steel scrap by means of laser-induced breakdown spectroscopy under ambient air atmospheres.

    Science.gov (United States)

    Kashiwakura, Shunsuke; Wagatsuma, Kazuaki

    2013-01-01

    For the rapid and precise sorting of steel scrap with relatively high contents of copper, laser-induced breakdown spectroscopy (LIBS) is a promising method. It has several advantages such that it can work under ambient air atmospheres, and specimens can be tested without any pretreatment, such as acid digestion, polishing of the surface of the specimens, etc. For the application of LIBS for actual steel scrap, we obtained emission spectra by an LIBS system, which was mainly comprised of an Nd:YAG laser, an Echelle-type spectrometer, and an ICCD detector. The standard reference materials (SRMs) of JISF FXS 350-352, which are Fe-Cu binary alloy and have certified concentrations of copper, were employed for making calibration lines. Considering spectral interferences from the emission lines of the iron matrix in the alloys, Cu I lines having wavelengths of 324.754 and 327.396 nm could be chosen. In five replicate measurements of each SRM, shorter delay times after laser irradiation and longer gate widths for detecting the transient emission signal are suggested to be the optimal experiment parameters. In the determination process, utilizing the calibration line from Cu I 327.396 nm was better because of less spectral interference. By using 200 pulsed laser shots for the measurement sequence, a limit of detection of 0.004 Cu at% could be obtained.

  14. Characterization of Machine Variability and Progressive Heat Treatment in Selective Laser Melting of Inconel 718

    Science.gov (United States)

    Prater, Tracie; Tilson, Will; Jones, Zack

    2015-01-01

    The absence of an economy of scale in spaceflight hardware makes additive manufacturing an immensely attractive option for propulsion components. As additive manufacturing techniques are increasingly adopted by government and industry to produce propulsion hardware in human-rated systems, significant development efforts are needed to establish these methods as reliable alternatives to conventional subtractive manufacturing. One of the critical challenges facing powder bed fusion techniques in this application is variability between machines used to perform builds. Even with implementation of robust process controls, it is possible for two machines operating at identical parameters with equivalent base materials to produce specimens with slightly different material properties. The machine variability study presented here evaluates 60 specimens of identical geometry built using the same parameters. 30 samples were produced on machine 1 (M1) and the other 30 samples were built on machine 2 (M2). Each of the 30-sample sets were further subdivided into three subsets (with 10 specimens in each subset) to assess the effect of progressive heat treatment on machine variability. The three categories for post-processing were: stress relief, stress relief followed by hot isostatic press (HIP), and stress relief followed by HIP followed by heat treatment per AMS 5664. Each specimen (a round, smooth tensile) was mechanically tested per ASTM E8. Two formal statistical techniques, hypothesis testing for equivalency of means and one-way analysis of variance (ANOVA), were applied to characterize the impact of machine variability and heat treatment on six material properties: tensile stress, yield stress, modulus of elasticity, fracture elongation, and reduction of area. This work represents the type of development effort that is critical as NASA, academia, and the industrial base work collaboratively to establish a path to certification for additively manufactured parts. For future

  15. Rapid differentiation of Listeria monocytogenes epidemic clones III and IV and their intact compared with heat-killed populations using Fourier transform infrared spectroscopy and chemometrics.

    Science.gov (United States)

    Nyarko, Esmond B; Puzey, Kenneth A; Donnelly, Catherine W

    2014-06-01

    The objectives of this study were to determine if Fourier transform infrared (FT-IR) spectroscopy and multivariate statistical analysis (chemometrics) could be used to rapidly differentiate epidemic clones (ECs) of Listeria monocytogenes, as well as their intact compared with heat-killed populations. FT-IR spectra were collected from dried thin smears on infrared slides prepared from aliquots of 10 μL of each L. monocytogenes ECs (ECIII: J1-101 and R2-499; ECIV: J1-129 and J1-220), and also from intact and heat-killed cell populations of each EC strain using 250 scans at a resolution of 4 cm(-1) in the mid-infrared region in a reflectance mode. Chemometric analysis of spectra involved the application of the multivariate discriminant method for canonical variate analysis (CVA) and linear discriminant analysis (LDA). CVA of the spectra in the wavelength region 4000 to 600 cm(-1) separated the EC strains while LDA resulted in a 100% accurate classification of all spectra in the data set. Further, CVA separated intact and heat-killed cells of each EC strain and there was 100% accuracy in the classification of all spectra when LDA was applied. FT-IR spectral wavenumbers 1650 to 1390 cm(-1) were used to separate heat-killed and intact populations of L. monocytogenes. The FT-IR spectroscopy method allowed discrimination between strains that belong to the same EC. FT-IR is a highly discriminatory and reproducible method that can be used for the rapid subtyping of L. monocytogenes, as well as for the detection of live compared with dead populations of the organism. Fourier transform infrared (FT-IR) spectroscopy and multivariate statistical analysis can be used for L. monocytogenes source tracking and for clinical case isolate comparison during epidemiological investigations since the method is capable of differentiating epidemic clones and it uses a library of well-characterized strains. The FT-IR method is potentially less expensive and more rapid compared to genetic

  16. Rapid determination of the radiochemical purity of 99mTc-antimony trisulfide colloid prepared by standard and alternative heating methods.

    Science.gov (United States)

    Smyth, Douglas R

    2006-09-01

    The purpose of this study was to validate a rapid quality control method for the lymphoscintigraphic tracer 99mTc-antimony trisulfide colloid (99mTc-ATC). ATC was labeled with 99mTc according to the manufacturer's instructions as well as by alternative heating conditions designed to provide a range of percentages of radiochemical purity (RCP): the tracer was prepared in a dry block heater with heating cavities of different sizes, the temperature of the heating block was varied from 70 degrees C to 115 degrees C, or the duration of heating was varied from 15 to 35 min. Anion-exchange minicolumns were trialled to separate any 99mTc-pertechnetate impurity from 99mTc-ATC with physiologic saline as the eluent. Quality control results were compared with the results from the manufacturer's recommended method, which uses an instant thin-layer chromatography (ITLC) strip with saline as the migrating solution. The quality control results obtained with a cartridge method in 2-3 min compared favorably with those obtained with the ITLC method with saline when the tracer was prepared by heating at 115 degrees C in a dry block heater for 35 min (RCPs, 99.4%+/-0.3% [mean+/-SD] and 99.2%+/-0.3%, respectively; n=25). The cartridge and ITLC quality control results also were in excellent agreement (correlation coefficient, 0.99) over a range of RCPs (80%-100%). An alternative anion-exchange cartridge that was tested in this study was not suitable for assaying the RCP of 99mTc-ATC because of the complete retention of 99mTc-pertechnetate on the sorbent. Compared with the established ITLC method, the cartridge quality control method tested in this study is rapid and provides a reliable assessment of the RCP of 99mTc-ATC. For the preparation of 99mTc-ATC, a dry block heater can be successfully substituted for a boiling water bath and is recommended for heating at high altitudes.

  17. A study on an efficient prediction of welding deformation for T-joint laser welding of sandwich panel PART I : Proposal of a heat source model

    Directory of Open Access Journals (Sweden)

    Jae Woong Kim

    2013-09-01

    Full Text Available The use of I-Core sandwich panel has increased in cruise ship deck structure since it can provide similar bending strength with conventional stiffened plate while keeping lighter weight and lower web height. However, due to its thin plate thickness, i.e. about 4~6 mm at most, it is assembled by high power CO2 laser welding to minimize the welding deformation. This research proposes a volumetric heat source model for T-joint of the I-Core sandwich panel and a method to use shell element model for a thermal elasto-plastic analysis to predict welding deformation. This paper, Part I, focuses on the heat source model. A circular cone type heat source model is newly suggested in heat transfer analysis to realize similar melting zone with that observed in experiment. An additional suggestion is made to consider negative defocus, which is commonly applied in T-joint laser welding since it can provide deeper penetration than zero defocus. The proposed heat source is also verified through 3D thermal elasto-plastic analysis to compare welding deformation with experimental results. A parametric study for different welding speeds, defocus values, and welding powers is performed to investigate the effect on the melting zone and welding deformation. In Part II, focuses on the proposed method to employ shell element model to predict welding deformation in thermal elasto-plastic analysis instead of solid element model.

  18. Rapid alkali catalyzed transesterification of microalgae lipids to biodiesel using simultaneous cooling and microwave heating and its optimization.

    Science.gov (United States)

    Chee Loong, Teo; Idris, Ani

    2014-12-01

    Biodiesel with improved yield was produced from microalgae biomass under simultaneous cooling and microwave heating (SCMH). Nannochloropsis sp. and Tetraselmis sp. which were known to contain higher lipid species were used. The yield obtained using this novel technique was compared with the conventional heating (CH) and microwave heating (MWH) as the control method. The results revealed that the yields obtained using the novel SCMH were higher; Nannochloropsis sp. (83.33%) and Tetraselmis sp. (77.14%) than the control methods. Maximum yields were obtained using SCMH when the microwave was set at 50°C, 800W, 16h of reaction with simultaneous cooling at 15°C; and water content and lipid to methanol ratio in reaction mixture was kept to 0 and 1:12 respectively. GC analysis depicted that the biodiesel produced from this technique has lower carbon components (<19 C) and has both reasonable CN and IV reflecting good ignition and lubricating properties. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. Observation of dust particles ejected from the tungsten surface by transient heat flux with small-angle scattering of cw laser light

    Directory of Open Access Journals (Sweden)

    L.N. Vyacheslavov

    2017-08-01

    Full Text Available A new test facility for experimental simulation of transient heat load expected in the ITER divertor during unmitigated events is developed. Application of a long-pulse (0.1–0.3ms wide-aperture (up to 2cm2 electron beam as a heating device provides powerful energy loads at a tungsten target with FHF> 250MJm−2s−0.5. Dynamics of tungsten particles in the ablation plume is investigated with a novel for PSI experiments small-angle laser light scattering technique. The threshold of intense droplet generation and dynamics of particles sizes are estimated.

  20. Laser-heating and Radiance Spectrometry for the Study of Nuclear Materials in Conditions Simulating a Nuclear Power Plant Accident.

    Science.gov (United States)

    Manara, Dario; Soldi, Luca; Mastromarino, Sara; Boboridis, Kostantinos; Robba, Davide; Vlahovic, Luka; Konings, Rudy

    2017-12-14

    Major and severe accidents have occurred three times in nuclear power plants (NPPs), at Three Mile Island (USA, 1979), Chernobyl (former USSR, 1986) and Fukushima (Japan, 2011). Research on the causes, dynamics, and consequences of these mishaps has been performed in a few laboratories worldwide in the last three decades. Common goals of such research activities are: the prevention of these kinds of accidents, both in existing and potential new nuclear power plants; the minimization of their eventual consequences; and ultimately, a full understanding of the real risks connected with NPPs. At the European Commission Joint Research Centre's Institute for Transuranium Elements, a laser-heating and fast radiance spectro-pyrometry facility is used for the laboratory simulation, on a small scale, of NPP core meltdown, the most common type of severe accident (SA) that can occur in a nuclear reactor as a consequence of a failure of the cooling system. This simulation tool permits fast and effective high-temperature measurements on real nuclear materials, such as plutonium and minor actinide-containing fission fuel samples. In this respect, and in its capability to produce large amount of data concerning materials under extreme conditions, the current experimental approach is certainly unique. For current and future concepts of NPP, example results are presented on the melting behavior of some different types of nuclear fuels: uranium-plutonium oxides, carbides, and nitrides. Results on the high-temperature interaction of oxide fuels with containment materials are also briefly shown.

  1. Implementation of a multisource model for gold nanoparticle-mediated plasmonic heating with near-infrared laser by the finite element method.

    Science.gov (United States)

    Reynoso, Francisco J; Lee, Chae-Deok; Cheong, Seong-Kyun; Cho, Sang Hyun

    2013-07-01

    The use of optically tunable gold nanoparticles (GNPs) in conjunction with near-infrared (NIR) laser has emerged as an attractive option for laser-induced thermal therapy (LITT), as it capitalizes on plasmonic heating of GNPs tuned to absorb light strongly in the NIR region. Previously, the authors developed a multisource model to predict the temperature change in a GNP-laden tissue-like medium illuminated by NIR laser and implemented it by a linear superposition (LS) method combining analytic and finite element method (FEM) solutions. While it is intuitive and straightforward, the LS approach might be somewhat cumbersome to implement for realistic LITT cases because it requires separate calculations of the temperature change due to individual GNP heat sources and the laser heat source. Therefore, the current investigation aimed to develop a simpler yet mathematically more elegant and computationally more efficient method solely based on FEM to implement the authors' multisource model. A multisource FEM model was developed to calculate the full spatiotemporal temperature distribution due to all heat sources (i.e., individual GNPs and the laser heat source) by solving the heat diffusion equation with multiple heat sources using FEM. This model was tested for its validity using two computational phantoms, a two-layer GNP-laden cylindrical phantom and a breast phantom with a GNP-laden microcavity. For comparison, the results for the two phantom cases were also obtained from the LS method. For the two-layer phantom case, the FEM approach resulted in a maximum temperature increase of 16.4 °C at a depth of 1.35 cm, 2.5 mm below the interface between the two layers, while the LS method produced a maximum temperature increase of 16.7 °C at a depth of 1.3 cm, 2 mm below the interface between the two layers. A comparison of the depth versus temperature changes obtained from the two approaches showed reasonably good agreement within 6%. In the breast phantom case, the LS

  2. A (S)TEM Gas Cell Holder with Localized Laser Heating for In Situ Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Mehraeen, Shareghe [Univ. of California, Davis, CA (United States). Dept. of Molecular and Cellular Biology; McKeown, Joseph T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Condensed Matter and Materials Division; Deshmukh, Pushkarraj V. [E.A. Fischione Instruments, Inc., Export, PA (United States); Evans, James E. [Univ. of California, Davis, CA (United States). Dept. of Molecular and Cellular Biology; Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Chemical and Materials Science Division; Abellan, Patricia [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Chemical and Materials Science Division; Xu, Pinghong [Univ. of California, Davis, CA (United States). Dept. of Chemical Engineering and Materials Science; Reed, Bryan W. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Condensed Matter and Materials Division; Taheri, Mitra L. [Drexel Univ., Philadelphia, PA (United States). Dept. of Materials Science & Engineering; Fischione, Paul E. [E.A. Fischione Instruments, Inc., Export, PA (United States); Browning, Nigel D. [Univ. of California, Davis, CA (United States). Dept. of Molecular and Cellular Biology; Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Chemical and Materials Science Division; Univ. of California, Davis, CA (United States). Dept. of Chemical Engineering and Materials Science

    2013-03-04

    We report that the advent of aberration correction for transmission electron microscopy has transformed atomic resolution imaging into a nearly routine technique for structural analysis. Now an emerging frontier in electron microscopy is the development of in situ capabilities to observe reactions at atomic resolution in real time and within realistic environments. Here we present a new in situ gas cell holder that is designed for compatibility with a wide variety of sample type (i.e., dimpled 3-mm discs, standard mesh grids, various types of focused ion beam lamellae attached to half grids). Its capabilities include localized heating and precise control of the gas pressure and composition while simultaneously allowing atomic resolution imaging at ambient pressure. The results show that 0.25-nm lattice fringes are directly visible for nanoparticles imaged at ambient pressure with gas path lengths up to 20 μm. Additionally, we quantitatively demonstrate that while the attainable contrast and resolution decrease with increasing pressure and gas path length, resolutions better than 0.2 nm should be accessible at ambient pressure with gas path lengths less than the 15 μm utilized for these experiments.

  3. Effect of the laser and light-emitting diode (LED) phototherapy on midpalatal suture bone formation after rapid maxilla expansion: a Raman spectroscopy analysis.

    Science.gov (United States)

    Rosa, Cristiane Becher; Habib, Fernando Antonio Lima; de Araújo, Telma Martins; Aragão, Juliana Silveira; Gomes, Rafael Soares; Barbosa, Artur Felipe Santos; Silveira, Landulfo; Pinheiro, Antonio L B

    2014-05-01

    The aim of this study was to analyze the effect of laser or light-emitting diode (LED) phototherapy on the bone formation at the midpalatal suture after rapid maxilla expansion. Twenty young adult male rats were divided into four groups with 8 days of experimental time: group 1, no treatment; group 2, expansion; group 3, expansion and laser irradiation; and group 4, expansion and LED irradiation. In groups 3 and 4, light irradiation was in the first, third, and fifth experimental days. In all groups, the expansion was accomplished with a helicoid 0.020" stainless steel orthodontic spring. A diode laser (λ780 nm, 70 mW, spot of 0.04 cm(2), t = 257 s, spatial average energy fluence (SAEF) of 18 J/cm(2)) or a LED (λ850 nm, 150 mW ± 10 mW, spot of 0.5 cm(2), t = 120 s, SAEF of 18 J/cm(2)) were used. The samples were analyzed by Raman spectroscopy carried out at midpalatal suture and at the cortical area close to the suture. Two Raman shifts were analyzed: ∼ 960 (phosphate hydroxyapatite) and ∼ 1,450 cm(-1) (lipids and protein). Data was submitted to statistical analysis. Significant statistical difference (p ≤ 0.05) was found in the hydroxyapatite (CHA) peaks among the expansion group and the expansion and laser or LED groups. The LED group presented higher mean peak values of CHA. No statistical differences were found between the treated groups as for collagen deposition, although LED also presented higher mean peak values. The results of this study using Raman spectral analysis indicate that laser and LED light irradiation improves deposition of CHA in the midpalatal suture after orthopedic expansion.

  4. Data demonstrating the effects of build orientation and heat treatment on fatigue behavior of selective laser melted 17–4 PH stainless steel

    OpenAIRE

    Yadollahi, Aref; Simsiriwong, Jutima; Thompson, Scott M.; Shamsaei, Nima

    2016-01-01

    Axial fully-reversed strain-controlled ( R = ? 1 ) fatigue experiments were performed to obtain data demonstrating the effects of building orientation (i.e. vertical versus horizontal) and heat treatment on the fatigue behavior of 17?4 PH stainless steel (SS) fabricated via Selective Laser Melting (SLM) (Yadollahi et al., submitted for publication [1]). This data article provides detailed experimental data including cyclic stress-strain responses, variations of peak stresses during cyclic def...

  5. Liquid Phase Separation and the Aging Effect on Mechanical and Electrical Properties of Laser Rapidly Solidified Cu100−xCrx Alloys

    Directory of Open Access Journals (Sweden)

    Song-Hua Si

    2015-11-01

    Full Text Available Duplex structure Cu-Cr alloys are widely used as contact materials. They are generally designed by increasing the Cr content for the hardness improvement, which, however, leads to the unfavorable rapid increase of the electrical resistivity. The solidification behavior of Cu100−xCrx (x = 4.2, 25 and 50 in wt.% alloys prepared by laser rapid solidification is studied here, and their hardness and electrical conductivity after aging are measured. The results show that the Cu-4.2%Cr alloy has the most desirable combination of hardness and conductive properties after aging in comparison with Cu-25%Cr and Cu-50%Cr alloys. Very importantly, a 50% improvement in hardness is achieved with a simultaneous 70% reduction in electrical resistivity. The reason is mainly attributed to the liquid phase separation occurring in the Cu-4.2%Cr alloy, which introduces a large a

  6. 110 GHz rapid, continous tuning from an optical parametric oscillator pumped by a fiber-amplified DBR diode laser

    NARCIS (Netherlands)

    Lindsay, I.D.; Adhimoolam, B.; Gross, P.; Klein, M.E.; Boller, Klaus J.

    2005-01-01

    A singly-resonant continuous-wave optical parametric oscillator (cw-OPO) pumped by a fiber-amplified diode laser is described. Tuning of the pump source allowed the OPO output to be tuned continuously, without mode-hops, over 110 GHz in 29 ms. Discontinuous pump tuning over 20 nm in the region of

  7. Microstructure and Phase Formation in a Rapidly Solidified Laser-Deposited Ni-Cr-B-Si-C Hardfacing Alloy

    NARCIS (Netherlands)

    Hemmati, Ismail; Ocelik, Vaclav; Csach, Kornel; de Hosson, Jeff Th M.

    In this study, microstructural evolutions and phase selection phenomena during laser deposition of a hardfacing Ni-Cr-B-Si-C alloy at different processing conditions are experimentally investigated. The results show that even minor variations in the thermal conditions during solidification can

  8. Ultra-high thermally conductive and rapid heat responsive poly(benzobisoxazole) nanocomposites with self-aligned graphene.

    Science.gov (United States)

    Zhao, Weifeng; Kong, Jie; Liu, Hu; Zhuang, Qiang; Gu, Junwei; Guo, Zhanhu

    2016-12-28

    Self-alignment of thermally reduced graphene sheets (TRG) that enable highly efficient heat transfer paths in their poly(p-phenylene benzobisoxazole) (PBO)-based nanocomposite films along the in-plane direction was achieved for the first time without any assistance of an external magnetic or an electric field. In the in-plane direction, the nanocomposite films possess an ultra-high thermal diffusivity (900-1000 mm(2) s(-1)) and a thermal conductivity (50 W m(-1) K(-1)) with a TRG concentration graphene filler loading. The arranged TRG was also found to display a high efficiency for PBO reinforcement. A 64% increase in the Young's modulus was achieved by the addition of only 0.35 vol% of TRG, corresponding to a reinforcement value as high as 747 ± 38 GPa, due to effective load transfer between the PBO matrix and TRG sheets via strong interfacial interactions. Moreover, the highly ordered graphene in PBO could provide good candidates for effective heat shielding barriers, and thus the prepared PBO composites exhibit a thermal stability remarkably higher than that of neat PBO resin.

  9. Laser-assisted chemical vapor deposition setup for fast synthesis of graphene patterns

    Science.gov (United States)

    Zhang, Chentao; Zhang, Jianhuan; Lin, Kun; Huang, Yuanqing

    2017-05-01

    An automatic setup based on the laser-assisted chemical vapor deposition method has been developed for the rapid synthesis of graphene patterns. The key components of this setup include a laser beam control and focusing unit, a laser spot monitoring unit, and a vacuum and flow control unit. A laser beam with precision control of laser power is focused on the surface of a nickel foil substrate by the laser beam control and focusing unit for localized heating. A rapid heating and cooling process at the localized region is induced by the relative movement between the focalized laser spot and the nickel foil substrate, which causes the decomposing of gaseous hydrocarbon and the out-diffusing of excess carbon atoms to form graphene patterns on the laser scanning path. All the fabrication parameters that affect the quality and number of graphene layers, such as laser power, laser spot size, laser scanning speed, pressure of vacuum chamber, and flow rates of gases, can be precisely controlled and monitored during the preparation of graphene patterns. A simulation of temperature distribution was carried out via the finite element method, providing a scientific guidance for the regulation of temperature distribution during experiments. A multi-layer graphene ribbon with few defects was synthesized to verify its performance of the rapid growth of high-quality graphene patterns. Furthermore, this setup has potential applications in other laser-based graphene synthesis and processing.

  10. Rapid identification of Mycobacterium avium clinical isolates by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

    Science.gov (United States)

    Lin, Chuan-Sheng; Su, Chih-Cheng; Hsieh, Shang-Chen; Lu, Chia-Chen; Wu, Tsu-Lan; Jia, Ju-Hsin; Wu, Ting-Shu; Han, Chau-Chung; Tsai, Wen-Cherng; Lu, Jang-Jih; Lai, Hsin-Chih

    2015-04-01

    Rapid and accurate discrimination of Mycobacterium avium from other mycobacteria is essential for appropriate therapeutic management and timely intervention for infection control. However, routine clinical identification methods for M. avium are both time consuming and labor intensive. In the present study, matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) was used to identify specific cellular protein pattern for rapid identification of M. avium isolates. A total of 40 clinically relevant Mycobacterium strains comprising 13 distinct species were enrolled for the MALDI-TOF MS identification. A 10-minute extraction-free examination procedure was set up to obtain mass spectral fingerprints from whole bacterial cells. The characteristic mass spectral peak patterns in the m/z (mass/charge ratio) range of 5-20 kDa can be obtained within 10 minutes. The species-specific mass spectra for M. avium is identified and can be differentiated from as Mycobacterium strains. This technique shortens and simplifies the identification procedure of MALDI-TOF MS and may further extend the mycobacterial MALDI-TOF MS database. Simplicity and rapidity of identification procedures make MALDI-TOF MS an attractive platform in routine identification of mycobacteria. MALDI-TOF MS is applicable for rapid discrimination of M. avium from other Mycobacterium species, and shows its potential for clinical application. Copyright © 2013. Published by Elsevier B.V.

  11. Rapid on-site detection of explosives on surfaces by ambient pressure laser desorption and direct inlet single photon ionization or chemical ionization mass spectrometry.

    Science.gov (United States)

    Ehlert, S; Hölzer, J; Rittgen, J; Pütz, M; Schulte-Ladbeck, R; Zimmermann, R

    2013-09-01

    Considering current security issues, powerful tools for detection of security-relevant substances such as traces of explosives and drugs/drug precursors related to clandestine laboratories are required. Especially in the field of detection of explosives and improvised explosive devices, several relevant compounds exhibit a very low vapor pressure. Ambient pressure laser desorption is proposed to make these substances available in the gas phase for the detection by adapted mass spectrometers or in the future with ion-mobility spectrometry as well. In contrast to the state-of-the-art thermal desorption approach, by which the sample surface is probed for explosive traces by a wipe pad being transferred to a thermal desorber unit, by the ambient pressure laser desorption approach presented here, the sample is directly shockwave ablated from the surface. The laser-dispersed molecules are sampled by a heated sniffing capillary located in the vicinity of the ablation spot into the mass analyzer. This approach has the advantage that the target molecules are dispersed more gently than in a thermal desorber unit where the analyte molecules may be decomposed by the thermal intake. In the technical realization, the sampling capillary as well as the laser desorption optics are integrated in the tip of an endoscopic probe or a handheld sampling module. Laboratory as well as field test scenarios were performed, partially in cooperation with the Federal Criminal Police Office (Bundeskriminalamt, BKA, Wiesbaden, Germany), in order to demonstrate the applicability for various explosives, drugs, and drug precursors. In this work, we concentrate on the detection of explosives. A wide range of samples and matrices have been investigated successfully.

  12. 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.

  13. A rapid isotope ratio analysis protocol for nuclear solid materials using nano-second laser-ablation time-of-flight ICP-MS.

    Science.gov (United States)

    Bürger, S; Riciputi, L R

    2009-11-01

    The analysis of the isotopic composition of nuclear or non-nuclear solid materials is performed in a variety of fields, e.g., for quality assurance in the production of nuclear fuels, as signatures in forensics, nuclear safeguards, and non-proliferation control, in material characterization, geology, and archeology. We have investigated the capability of laser ablation (New Wave Research, 213 nm) coupled to time-of-flight (TOF) ICP-MS (GBC OptiMass 8000) as a rapid analytical protocol for multi-isotope screening of nuclear and non-nuclear solid samples. This includes natural and non-natural isotopic compositions for elements including Cu, Zr, Mo, Cd, In, Ba, Ta, W, Re, Pt, Pb, and U, in pure metals, alloys, and glasses. Without correcting for mass bias (mass fractionation), an overall precision and accuracy of about 4% (1 sigma) can be achieved by minimizing the deposited laser power and thus fractionation (mass removal based on thermal properties). The precision and accuracy in combination with literally no or minimized sample preparation enables a rapid isotope screening of solid samples that is of particular interest to support nuclear forensic and safeguard analysis.

  14. Analysis of Thermally Denatured Depth in Laser Vaporization for Benign Prostatic Hyperplasia using a Simulation of Light Propagation and Heat Transfer (secondary publication)

    Science.gov (United States)

    Takada, Junya; Honda, Norihiro; Hazama, Hisanao; Ioritani, Naomasa

    2016-01-01

    Background and Aims: Laser vaporization of the prostate is expected as a less invasive treatment for benign prostatic hyperplasia (BPH), via the photothermal effect. In order to develop safer and more effective laser vaporization of the prostate, it is essential to set optimal irradiation parameters based on quantitative evaluation of temperature distribution and thermally denatured depth in prostate tissue. Method: A simulation model was therefore devised with light propagation and heat transfer calculation, and the vaporized and thermally denatured depths were estimated by the simulation model. Results: The results of the simulation were compared with those of an ex vivo experiment and clinical trial. Based on the accumulated data, the vaporized depth strongly depended on the distance between the optical fiber and the prostate tissue, and it was suggested that contact laser irradiation could vaporize the prostate tissue most effectively. Additionally, it was suggested by analyzing thermally denatured depth comprehensively that laser irradiation at the distance of 3 mm between the optical fiber and the prostate tissue was useful for hemostasis. Conclusions: This study enabled quantitative and reproducible analysis of laser vaporization for BPH and will play a role in clarification of the safety and efficacy of this treatment. PMID:28765672

  15. Photolithography-free laser-patterned HF acid-resistant chromium-polyimide mask for rapid fabrication of microfluidic systems in glass

    Science.gov (United States)

    Zamuruyev, Konstantin O.; Zrodnikov, Yuriy; Davis, Cristina E.

    2017-01-01

    Excellent chemical and physical properties of glass, over a range of operating conditions, make it a preferred material for chemical detection systems in analytical chemistry, biology, and the environmental sciences. However, it is often compromised with SU8, PDMS, or Parylene materials due to the sophisticated mask preparation requirements for wet etching of glass. Here, we report our efforts toward developing a photolithography-free laser-patterned hydrofluoric acid-resistant chromium-polyimide tape mask for rapid prototyping of microfluidic systems in glass. The patterns are defined in masking layer with a diode-pumped solid-state laser. Minimum feature size is limited to the diameter of the laser beam, 30 µm minimum spacing between features is limited by the thermal shrinkage and adhesive contact of the polyimide tape to 40 µm. The patterned glass substrates are etched in 49% hydrofluoric acid at ambient temperature with soft agitation (in time increments, up to 60 min duration). In spite of the simplicity, our method demonstrates comparable results to the other current more sophisticated masking methods in terms of the etched depth (up to 300 µm in borosilicate glass), feature under etch ratio in isotropic etch (~1.36), and low mask hole density. The method demonstrates high yield and reliability. To our knowledge, this method is the first proposed technique for rapid prototyping of microfluidic systems in glass with such high performance parameters. The proposed method of fabrication can potentially be implemented in research institutions without access to a standard clean-room facility.

  16. Forced convective heat transfer in curved diffusers

    Science.gov (United States)

    Rojas, J.; Whitelaw, J. H.; Yianneskis, M.

    1987-01-01

    Measurements of the velocity characteristics of the flows in two curved diffusers of rectangular cross section with C and S-shaped centerlines are presented and related to measurements of wall heat transfer coefficients along the heated flat walls of the ducts. The velocity results were obtained by laser-Doppler anemometry in a water tunnel and the heat transfer results by liquid crystal thermography in a wind tunnel. The thermographic technique allowed the rapid and inexpensive measurement of wall heat transfer coefficients along flat walls of arbitrary boundary shapes with an accuracy of about 5 percent. The results show that an increase in secondary flow velocities near the heated wall causes an increase in the local wall heat transfer coefficient, and quantify the variation for maximum secondary-flow velocities in a range from 1.5 to 17 percent of the bulk flow velocity.

  17. Study of bacteriophage T4-encoded Dam DNA (adenine-N6)-methyltransferase binding with substrates by rapid laser UV cross-linking.

    Science.gov (United States)

    Evdokimov, Alexey A; Sclavi, Bianca; Zinoviev, Victor V; Malygin, Ernst G; Hattman, Stanley; Buckle, Malcolm

    2007-09-07

    DNA methyltransferases of the Dam family (including bacteriophage T4-encoded Dam DNA (adenine-N(6))-methyltransferase (T4Dam)) catalyze methyl group transfer from S-adenosyl-L-methionine (AdoMet), producing S-adenosyl-L-homocysteine (AdoHcy) and methylated adenine residues in palindromic GATC sequences. In this study, we describe the application of direct (i.e. no exogenous cross-linking reagents) laser UV cross-linking as a universal non-perturbing approach for studying the characteristics of T4Dam binding with substrates in the equilibrium and transient modes of interaction. UV irradiation of the enzyme.substrate complexes using an Nd(3+):yttrium aluminum garnet laser at 266 nm resulted in up to 3 and >15% yields of direct T4Dam cross-linking to DNA and AdoMet, respectively. Consequently, we were able to measure equilibrium constants and dissociation rates for enzyme.substrate complexes. In particular, we demonstrate that both reaction substrates, specific DNA and AdoMet (or product AdoHcy), stabilized the ternary complex. The improved substrate affinity for the enzyme in the ternary complex significantly reduced dissociation rates (up to 2 orders of magnitude). Several of the parameters obtained (such as dissociation rate constants for the binary T4Dam.AdoMet complex and for enzyme complexes with a nonfluorescent hemimethylated DNA duplex) were previously inaccessible by other means. However, where possible, the results of laser UV cross-linking were compared with those of fluorescence analysis. Our study suggests that rapid laser UV cross-linking efficiently complements standard DNA methyltransferase-related tools and is a method of choice to probe enzyme-substrate interactions in cases in which data cannot be acquired by other means.

  18. Laser Rapid Manufacturing of Stainless Steel 316L/Inconel718 Functionally Graded Materials: Microstructure Evolution and Mechanical Properties

    Directory of Open Access Journals (Sweden)

    Dongjiang Wu

    2010-01-01

    Full Text Available Two patterns of functionally graded materials (FGMs were successfully fabricated whose compositions gradually varied from 100% stainless steel 316L to 100% Inconel718 superalloy using laser engineered net shaping process. The microstructure characterization, composition analysis, and microhardness along the graded direction were investigated. The comparison revealed the distinctions in solidification behavior, microstructure evolution of two patterns. In the end, the abrasive wear resistance of the material was investigated.

  19. Basic Research Investigations into Multimode Laser and EM Launchers for Affordable Rapid Access to Space (Volumes 1 and 2)

    Science.gov (United States)

    2010-08-31

    to 13,000 RPM just prior to launch. During flight, skin friction forces apply a roll - damping torque on the vehicle that steadily reduces the...simulation of an airbreathing bell nozzle thruster using FLUENT ®. Tang et al. (2005) used a TEA CO2 laser to conduct experiments on a parabolic...trajectory was subsequently applied by Langener (2006) in his Fluent ® numerical simulations of flow fields over (and through) various Lightcraft engine

  20. Effects of low-level laser therapy on osteoblastic bone formation and relapse in an experimental rapid maxillary expansion model.

    Science.gov (United States)

    Aras, M H; Erkilic, S; Demir, T; Demirkol, M; Kaplan, D S; Yolcu, U

    2015-01-01

    The aim of this study was to investigate the effects of low-level laser therapy (LLLT) on osteoblastic bone formation and relapse during expansion of rat palatal sutures. Thirty-two Wistar rats were randomly allocated into two groups of 16 rats each. In the first group, LLLT was applied 4 days after expansion commenced. Seven days after expansion, retainers were applied for 10 days. The second group was similarly treated, with the exception of laser therapy. All rats were sacrificed on day 7 (n = 1) (the end of the expansion period; laser group (LG) 1 [LLLT 1] and control group (CG) 1 [control 1]) and day 17 (n = 8) (the end of the retention period; LG 2 [LLLT 2] and CG 2 [control 2]) for histological assessment. The LLLT 1 group had significantly higher numbers of osteoclasts than did the control 1 group (P = 0.036). No significant between-group difference in osteoblast cell or capillary numbers was evident when day 7 and 17 data were compared. Histologically, LLLT stimulated bone formation, as revealed by analysis after the retention period. LLLT during expansion may accelerate bone healing.

  1. Case report: Rapid improvement of crossed cerebellar diaschisis after intravascular laser irradiation of blood in a case of stroke.

    Science.gov (United States)

    Yang, Wan-Hua; Lin, Shiou-Ping; Chang, Shin-Tsu

    2017-01-01

    Crossed cerebellar diaschisis (CCD) is a poor prognostic factor after stroke because without immediate cerebral reperfusion no further improvements in the patient's condition can be achieved. We investigated the clinical effects of intravascular laser irradiation therapy (ILIB) on CCD and evaluated the therapeutic effect in the sub-acute post-stroke stage. The 77-year-old male with cerebral infarction in the territory of the right anterior cerebral artery only underwent conservative treatment including hydration and aspirin in the acute post-stroke stage. He was diagnosed as stroke based on the clinical presentations and imaging findings. Once the patient was in stable condition, he underwent a daily hour-long ILIB (He-Ne laser) for ten consecutive days during the sub-acute post-stroke stage. We used single-photon emission computed tomography (SPECT) before and after intravascular laser irradiation to detect changes in cerebral and cerebellar perfusion. Then, we compared the two images. CCD was detected using the first SPECT. After intervention by ILIB, the second SPECT showed greater perfusion in the affected cerebellar hemisphere. We found that ILIB helped eliminate CCD, which was previously shown to be an untreatable condition using any intervention during the sub-acute post-stroke stage. Stroke patients could therefore greatly benefit from ILIB.

  2. Simultaneous measurements of velocity, temperature, and pressure using rapid CW wavelength-modulation laser-induced fluorescence of OH

    Science.gov (United States)

    Chang, A. Y.; Battles, B. E.; Hanson, R. K.

    1990-01-01

    In high speed flows, laser induced fluorescence (LIF) on Doppler shifted transitions is an attractive technique for velocity measurement. LIF velocimetry was applied to combined single-point measurements of velocity, temperature, and pressure and 2-D imaging of velocity and pressure. Prior to recent research using NO, LIF velocimetry in combustion related flows relied largely on the use of seed molecules. Simultaneous, single-point LIF measurements is reported of velocity, temperature, and pressure using the naturally occurring combustion species OH. This experiment is an extension of earlier research in which a modified ring dye laser was used to make time resolved temperature measurements behind reflected shock waves by using OH absorption an in postflame gases by using OH LIF. A pair of fused-silica rhombs mounted on a single galvanonmeter in an intracavity-doubled Spectra-Physics 380 ring laser permit the UV output to be swept continuously over a few wave numbers at an effective frequency of 3kHz.

  3. Low-Temperature Rapid Fabrication of ZnO Nanowire UV Sensor Array by Laser-Induced Local Hydrothermal Growth

    Directory of Open Access Journals (Sweden)

    Sukjoon Hong

    2013-01-01

    Full Text Available We demonstrate ZnO nanowire based UV sensor by laser-induced hydrothermal growth of ZnO nanowire. By inducing a localized temperature rise using focused laser, ZnO nanowire array at ~15 μm size consists of individual nanowires with ~8 μm length and 200~400 nm diameter is readily synthesized on gold electrode within 30 min at the desired position. The laser-induced growth process is consecutively applied on two different points to bridge the micron gap between the electrodes. The resultant photoconductive ZnO NW interconnections display 2~3 orders increase in the current upon the UV exposure at a fixed voltage bias. It is also confirmed that the amount of photocurrent can be easily adjusted by changing the number of ZnO NW array junctions. The device exhibits clear response to the repeated UV illumination, suggesting that this process can be usefully applied for the facile fabrication of low-cost UV sensor array.

  4. Rapid metabolic profiling of Nicotiana tabacum defence responses against Phytophthora nicotianae using direct infrared laser desorption ionization mass spectrometry and principal component analysis.

    Science.gov (United States)

    Ibáñez, Alfredo J; Scharte, Judith; Bones, Philipp; Pirkl, Alexander; Meldau, Stefan; Baldwin, Ian T; Hillenkamp, Franz; Weis, Engelbert; Dreisewerd, Klaus

    2010-06-09

    Successful defence of tobacco plants against attack from the oomycete Phytophthora nicotianae includes a type of local programmed cell death called the hypersensitive response. Complex and not completely understood signaling processes are required to mediate the development of this defence in the infected tissue. Here, we demonstrate that different families of metabolites can be monitored in small pieces of infected, mechanically-stressed, and healthy tobacco leaves using direct infrared laser desorption ionization orthogonal time-of-flight mass spectrometry. The defence response was monitored for 1 - 9 hours post infection. Infrared laser desorption ionization orthogonal time-of-flight mass spectrometry allows rapid and simultaneous detection in both negative and positive ion mode of a wide range of naturally occurring primary and secondary metabolites. An unsupervised principal component analysis was employed to identify correlations between changes in metabolite expression (obtained at different times and sample treatment conditions) and the overall defence response.A one-dimensional projection of the principal components 1 and 2 obtained from positive ion mode spectra was used to generate a Biological Response Index (BRI). The BRI obtained for each sample treatment was compared with the number of dead cells found in the respective tissue. The high correlation between these two values suggested that the BRI provides a rapid assessment of the plant response against the pathogen infection. Evaluation of the loading plots of the principal components (1 and 2) reveals a correlation among three metabolic cascades and the defence response generated in infected leaves. Analysis of selected phytohormones by liquid chromatography electrospray ionization mass spectrometry verified our findings. The described methodology allows for rapid assessment of infection-specific changes in the plant metabolism, in particular of phenolics, alkaloids, oxylipins, and carbohydrates

  5. Rapid metabolic profiling of Nicotiana tabacum defence responses against Phytophthora nicotianae using direct infrared laser desorption ionization mass spectrometry and principal component analysis

    Directory of Open Access Journals (Sweden)

    Weis Engelbert

    2010-06-01

    Full Text Available Abstract Background Successful defence of tobacco plants against attack from the oomycete Phytophthora nicotianae includes a type of local programmed cell death called the hypersensitive response. Complex and not completely understood signaling processes are required to mediate the development of this defence in the infected tissue. Here, we demonstrate that different families of metabolites can be monitored in small pieces of infected, mechanically-stressed, and healthy tobacco leaves using direct infrared laser desorption ionization orthogonal time-of-flight mass spectrometry. The defence response was monitored for 1 - 9 hours post infection. Results Infrared laser desorption ionization orthogonal time-of-flight mass spectrometry allows rapid and simultaneous detection in both negative and positive ion mode of a wide range of naturally occurring primary and secondary metabolites. An unsupervised principal component analysis was employed to identify correlations between changes in metabolite expression (obtained at different times and sample treatment conditions and the overall defence response. A one-dimensional projection of the principal components 1 and 2 obtained from positive ion mode spectra was used to generate a Biological Response Index (BRI. The BRI obtained for each sample treatment was compared with the number of dead cells found in the respective tissue. The high correlation between these two values suggested that the BRI provides a rapid assessment of the plant response against the pathogen infection. Evaluation of the loading plots of the principal components (1 and 2 reveals a correlation among three metabolic cascades and the defence response generated in infected leaves. Analysis of selected phytohormones by liquid chromatography electrospray ionization mass spectrometry verified our findings. Conclusion The described methodology allows for rapid assessment of infection-specific changes in the plant metabolism, in particular

  6. Use of laser speckle contrast imaging to reveal changes in temperature and blood perfusion in the skin of healthy subjects after administration of heated moxa sticks and daiwenjiu ointment.

    Science.gov (United States)

    Xu, Qingyan; Yang, Jinsheng; Wang, Liang; Deng, Zi; Wang, Yingying; Yang, Li; Wu, Peng; Li, Liang

    2014-08-01

    To investigate the influence of heated moxa sticks ("moxibustion") and Daiwenjiu ointment (DO) on changes in temperature and blood perfusion volume on the skin of the backs of healthy subjects. DO was spread on the left side of the body, and the right side of the body was treated with a heated moxa stick. Images denoting blood perfusion and body temperature were collected 7-8 cm lateral to the spinous process of the sixth thoracic vertebra using laser speckle contrast imaging (LSCI). Data obtained from eight-frame images were analyzed and used to calculate the mean blood perfusion volume. Simultaneously, blood-perfusion images were collected from the body surface and used to compare the change in blood flow on the body surface and the actual position of imaging. After moxibustion, a rapid increase in blood perfusion volume and body temperature was noted in the local skin surface. The maximum blood perfusion volume and body temperature was noted at 20 min (P temperature (P temperature after treatment with moxibustion, but the respective changes seen in the DO group were gradual and moderate.

  7. Towards the geophysical regime in numerical dynamo models: studies of rapidly-rotating convection driven dynamos with low Pm and constant heat flux boundary conditions

    DEFF Research Database (Denmark)

    Sheyko, A.A.; Finlay, Chris; Marti, P.

    We present a set of numerical dynamo models with the convection strength varied by a factor of 30 and the ratio of magnetic to viscous diffusivities by a factor of 20 at rapid rotation rates (E =nu/(2 Omega d^2 ) = 10-6 and 10-7 ) using a heat flux outer BC. This regime has been little explored...... on the structure of the dynamos and how this changes in relation to the selection of control parameters, a comparison with the proposed rotating convection and dynamo scaling laws, energy spectra of steady solutions and inner core rotation rates. Magnetic field on the CMB. E=2.959*10-7, Ra=6591.0, Pm=0.05, Pr=1....

  8. The Effect of a Rapid Heating Rate, Mechanical Vibration and Surfactant Chemistry on the Structure–Property Relationships of Epoxy/Clay Nanocomposites

    Directory of Open Access Journals (Sweden)

    Kevin Magniez

    2013-08-01

    Full Text Available The role of processing conditions and intercalant chemistry in montmorillonite clays on the dispersion, morphology and mechanical properties of two epoxy/clay nanocomposite systems was investigated in this paper. This work highlights the importance of employing complementary techniques (X-ray diffraction, small angle X-ray scattering, optical microscopy and transmission electron microscopy to correlate nanomorphology to macroscale properties. Materials were prepared using an out of autoclave manufacturing process equipped to generate rapid heating rates and mechanical vibration. The results suggested that the quaternary ammonium surfactant on C30B clay reacted with the epoxy during cure, while the primary ammonium surfactant (I.30E catalysed the polymerisation reaction. These effects led to important differences in nanocomposite clay morphologies. The use of mechanical vibration at 4 Hz prior to matrix gelation was found to facilitate clay dispersion and to reduce the area fraction of I.30E clay agglomerates in addition to increasing flexural strength by over 40%.

  9. Rapid Characterization of Microalgae and Microalgae Mixtures Using Matrix-Assisted Laser Desorption Ionization Time-Of-Flight Mass Spectrometry (MALDI-TOF MS).

    Science.gov (United States)

    Barbano, Duane; Diaz, Regina; Zhang, Lin; Sandrin, Todd; Gerken, Henri; Dempster, Thomas

    2015-01-01

    Current molecular methods to characterize microalgae are time-intensive and expensive. Matrix Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) may represent a rapid and economical alternative approach. The objectives of this study were to determine whether MALDI-TOF MS can be used to: 1) differentiate microalgae at the species and strain levels and 2) characterize simple microalgal mixtures. A common protein extraction sample preparation method was used to facilitate rapid mass spectrometry-based analysis of 31 microalgae. Each yielded spectra containing between 6 and 56 peaks in the m/z 2,000 to 20,000 range. The taxonomic resolution of this approach appeared higher than that of 18S rDNA sequence analysis. For example, two strains of Scenedesmus acutus differed only by two 18S rDNA nucleotides, but yielded distinct MALDI-TOF mass spectra. Mixtures of two and three microalgae yielded relatively complex spectra that contained peaks associated with members of each mixture. Interestingly, though, mixture-specific peaks were observed at m/z 11,048 and 11,230. Our results suggest that MALDI-TOF MS affords rapid characterization of individual microalgae and simple microalgal mixtures.

  10. Rapid Characterization of Microalgae and Microalgae Mixtures Using Matrix-Assisted Laser Desorption Ionization Time-Of-Flight Mass Spectrometry (MALDI-TOF MS)

    Science.gov (United States)

    Barbano, Duane; Diaz, Regina; Zhang, Lin; Sandrin, Todd; Gerken, Henri; Dempster, Thomas

    2015-01-01

    Current molecular methods to characterize microalgae are time-intensive and expensive. Matrix Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) may represent a rapid and economical alternative approach. The objectives of this study were to determine whether MALDI-TOF MS can be used to: 1) differentiate microalgae at the species and strain levels and 2) characterize simple microalgal mixtures. A common protein extraction sample preparation method was used to facilitate rapid mass spectrometry-based analysis of 31 microalgae. Each yielded spectra containing between 6 and 56 peaks in the m/z 2,000 to 20,000 range. The taxonomic resolution of this approach appeared higher than that of 18S rDNA sequence analysis. For example, two strains of Scenedesmus acutus differed only by two 18S rDNA nucleotides, but yielded distinct MALDI-TOF mass spectra. Mixtures of two and three microalgae yielded relatively complex spectra that contained peaks associated with members of each mixture. Interestingly, though, mixture-specific peaks were observed at m/z 11,048 and 11,230. Our results suggest that MALDI-TOF MS affords rapid characterization of individual microalgae and simple microalgal mixtures. PMID:26271045

  11. Rapid detection of GM1 ganglioside in cerebrospinal fluid in dogs with GM1 gangliosidosis using matrix-assisted laser desorption ionization time-of-flight mass spectrometry.

    Science.gov (United States)

    Satoh, Hiroyuki; Yamauchi, Toyofumi; Yamasaki, Masahiro; Maede, Yoshimitsu; Yabuki, Akira; Chang, Hye-Sook; Asanuma, Taketoshi; Yamato, Osamu

    2011-11-01

    The concentration of GM1 (monosialotetrahexosyl ganglioside) in cerebrospinal fluid (CSF) is markedly increased in dogs with GM1 gangliosidosis due to GM1 accumulation in the central nervous system and leakage to the CSF. The present study established a rapid and simple method for detection of accumulated GM1 in the CSF in dogs with GM1 gangliosidosis using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI TOF MS) and discusses the usefulness of this method for the rapid diagnosis and/or high-risk screening of this disease in domestic animals. Cerebrospinal fluid was collected from normal dogs and 4- to 11-month-old Shiba dogs with GM1 gangliosidosis. The MALDI TOF MS analysis was carried out in combination with a special sample plate and a simple desalting step on the plate. Specific signs of GM1 could be detected in the standard GM1 solutions at concentrations of 50 nmol/l or more. The signs were also clearly detected in CSF (131-618 nmol/l) in affected dogs, but not in normal canine CSF (12 ± 5 nmol/l, mean ± standard deviation). The results demonstrated that MALDI TOF MS can detect GM1 accumulated in canine CSF even in the early stage of the disease. In conclusion, the rapid detection of increased CSF GM1 using MALDI TOF MS is a useful method for diagnosis and/or screening for canine GM1 gangliosidosis.

  12. MR thermometry analysis program for laser- or high-intensity focused ultrasound (HIFU)-induced heating at a clinical MR scanner

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eun Ju; Jeong, Ki Young; Oh, Seung Jae; Park, Eun Hae; Lee, Young Han; Suh, Jin Suck [Yonsei University College of Medicine, Seoul (Korea, Republic of); Kim, Dae Hong [National Cancer Center, Goyang (Korea, Republic of)

    2014-12-15

    Magnetic resonance (MR) thermometry is a noninvasive method for monitoring local temperature change during thermal therapy. In this study, a MR temperature analysis program was established for a laser with gold nanorods (GNRs) and high-intensity focused ultrasound (HIFU)-induced heating MR thermometry. The MR temperature map was reconstructed using the water proton resonance frequency (PRF) method. The temperature-sensitive phase difference was acquired by using complex number subtraction instead of direct phase subtraction in order to avoid another phase unwrapping process. A temperature map-analyzing program was developed and implemented in IDL (Interactive Data Language) for effective temperature monitoring. This one program was applied to two different heating devices at a clinical MR scanner. All images were acquired with the fast spoiled gradient echo (fSPGR) pulse sequence on a 3.0 T GE Discovery MR750 scanner with an 8-channel knee array coil or with a home-built small surface coil. The analyzed temperature values were confirmed by using values simultaneously measured with an optical temperature probe (R{sup 2} = 0.996). The temperature change in small samples induced by a laser or by HIFU was analyzed by using a raw data, that consisted of complex numbers. This study shows that our MR thermometry analysis program can be used for thermal therapy study with a laser or HIFU at a clinical MR scanner. It can also be applied to temperature monitoring for any other thermal therapy based on the PRF method.

  13. Development of Technology and Equipment of the Automated Laser Welding for Manufacturing Heat Exchanger Details of Marine Engines

    Directory of Open Access Journals (Sweden)

    Shelyagin, V.D.

    2014-09-01

    Full Text Available Based on the developed automated laser welding technology for flat tubes of copper-nickel alloys laser welding complex technological equipment, which can be applied on the enterprises of machine building, aerospace, shipbuilding and automobile industries, was designed and created. To control the integrity of welded flat tubes a technique, which consists in testing sample pressure and finding defective sections by laser interferometry in the automated mode, was developed. Specialized welding head was designed and manufactured for the industrial use of the developed laser welding technology.

  14. Ultra rapid direct heating synthesis of ZnO nanorods with improved light trapping from stacked photoanodes for high efficiency photocatalytic water splitting

    Science.gov (United States)

    Cheat Lee, Wei; Fang, Yuanxing; Commandeur, Daniel; Qian, Rong; Al-Abdullah, Zainab T. Y.; Chen, Qiao

    2017-09-01

    An ultra rapid growth method for vertically aligned ZnO nanorod (NR) thin films on metal meshes was developed using a direct heating synthesis technique. A typical NR growth rate of 10 μm h-1 was achieved. The effects of the applied heating power and growth duration on the morphologies of ZnO nanostructures were examined. High density surface defects were formed on the ZnO NRs, which is responsible for slow charge recombination and high efficiency in the photoelectrochemical (PEC) water splitting process. The light absorption for a photoanode was significantly improved by light trapping using a 3D stacked metal mesh photoanode structure. With the internal reflection between the stacked photoanodes, the final light leakage is minimised. The light absorption in the stacked photoanode is improved without restricting the charge transportation. In comparison with a single mesh photoanode and a chemical bath deposition grown flat photoanode, the PEC water splitting efficiency from the stacked photoanode was increased by a factor of 2.6 and 6.1 respectively.

  15. Detection and mapping of Cannabinoids in single hair samples through rapid derivatization- Matrix-Assisted Laser Desorption Ionization Mass Spectrometry

    OpenAIRE

    Beasley, Emma; Francese, Simona; Bassindale, Thomas

    2016-01-01

    The sample preparation method reported in this work has permitted for the first time the application of Matrix Assisted Laser Desorption Ionization Mass Spectrometry Profiling and Imaging (MALDI-MSP and MALDI-MSI) for the detection and mapping of cannabinoids in a single hair sample. MALDI-MSI analysis of hair samples has recently been suggested as an alternative technique to traditional methods of GC-MS and LC-MS due to simpler sample preparation, the ability to detect a narrower time frame ...

  16. Rapid infrared wavelength access with a picosecond PPLN OPO synchronously pumped by a mode-locked diode laser

    NARCIS (Netherlands)

    Klein, M.E.; Robertson, A.; Tremont, M.A.; Wallenstein, R.; Boller, Klaus J.

    2001-01-01

    We theoretically and experimentally investigate wavelength tuning of synchronously pumped optical parametric oscillators (OPOs) on changing the cavity length or the pump-repetition rate. Conditions for rapid and wide-range wavelength access are derived. Using an OPO pumped directly by a mode-locked

  17. Creation of digital heat consumption maps using 3D laser scanning data. Assessing the cogeneration potential of Nordrhein-Westfalen; Erstellung digitaler Waermebedarfskarten mit 3D-Laserscanningdaten. Potenzialermittlung von KWK in NRW

    Energy Technology Data Exchange (ETDEWEB)

    Eikmeier, Bernd [Bremer Energie Institut, Bremen (Germany)

    2011-11-15

    Digital heat consumption maps are an ideal basis for the development of supply strategies, especially for systematic further development of district heating pipeline systems. In order to define the cogeneration potential of residential areas in the German state of Nordrhein-Westfalen, Bremer Energie Institut for the first time used 3D laser scanning data to establish a high-resolution digital heat atlas for seven model communities.

  18. Crystal structure and nanotopographical features on the surface of heat-treated and anodized porous titanium biomaterials produced using selective laser melting

    Energy Technology Data Exchange (ETDEWEB)

    Amin Yavari, S., E-mail: s.aminyavari@tudelft.nl [Faculty of Mechanical, Maritime, and Materials Engineering, Delft University of Technology (TU Delft), Mekelweg 2, 2628 CD Delft (Netherlands); FT Innovations BV, Braamsluiper 1, 5831 PW Boxmeer (Netherlands); Wauthle, R. [KU Leuven, Department of Mechanical Engineering, Section Production Engineering, Machine Design and Automation (PMA), Celestijnenlaan 300B, 3001 Leuven (Belgium); LayerWise NV, Kapeldreef 60, Leuven (Belgium); Böttger, A.J. [Faculty of Mechanical, Maritime, and Materials Engineering, Delft University of Technology (TU Delft), Mekelweg 2, 2628 CD Delft (Netherlands); Schrooten, J. [Department of Metallurgy and Materials Engineering, KU Leuven, Kasteelpark Arenberg 44 PB 2450, 3001 Heverlee (Belgium); Weinans, H. [Faculty of Mechanical, Maritime, and Materials Engineering, Delft University of Technology (TU Delft), Mekelweg 2, 2628 CD Delft (Netherlands); Department of Orthopedics and Department of Rheumatology, UMC Utrecht, Heidelberglaan 100, 3584 CX Utrecht (Netherlands); Zadpoor, A.A. [Faculty of Mechanical, Maritime, and Materials Engineering, Delft University of Technology (TU Delft), Mekelweg 2, 2628 CD Delft (Netherlands)

    2014-01-30

    Porous titanium biomaterials manufactured using additive manufacturing techniques such as selective laser melting are considered promising materials for orthopedic applications where the biomaterial needs to mimic the properties of bone. Despite their appropriate mechanical properties and the ample pore space they provide for bone ingrowth and osseointegration, porous titanium structures have an intrinsically bioinert surface and need to be subjected to surface bio-functionalizing procedures to enhance their in vivo performance. In this study, we used a specific anodizing process to build a hierarchical oxide layer on the surface of porous titanium structures made by selective laser melting of Ti6Al4V ELI powder. The hierarchical structure included both nanotopographical features (nanotubes) and micro-features (micropits). After anodizing, the biomaterial was heat treated in Argon at different temperatures ranging between 400 and 600 °C for either 1 or 2 h to improve its bioactivity. The effects of applied heat treatment on the crystal structure of TiO{sub 2} nanotubes and the nanotopographical features of the surface were studied using scanning electron microscopy and X-ray diffraction. It was shown that the transition from the initial crystal structure, i.e. anatase, to rutile occurs between 500 and 600 °C and that after 2 h of heat treatment at 600 °C the crystal structure is predominantly rutile. The nanotopographical features of the surface were found to be largely unchanged for heat treatments carried out at 500 °C or below, whereas they were partially or largely disrupted after heat treatment at 600 °C. The possible implications of these findings for the bioactivity of porous titanium structures are discussed.

  19. Influence of heat treatments on the microstructure and tensile behaviour of selective laser melting-produced TI-6AL-4V parts

    Directory of Open Access Journals (Sweden)

    Ter Haar, Gerrit Matthys

    2016-11-01

    Full Text Available In industry, post-process heat treatments of Ti-6Al-4V are performed with the aim of improving its tensile behaviour. While heat treatments of wrought Ti6Al4V have been standardised (e.g., Aerospace Material Specification H-81200, heat treatments of selective laser melting (SLM-produced Ti-6Al-4V lacks research and understanding. Significant concern exists about SLM Ti6-Al-4V’s achievable ductility attributed to its martensitic (α’ phase. In this research, heat treatments at a range of temperatures are applied to SLM-produced Ti-6Al-4V tensile samples. Microstructural analysis (both optically and through electron backscatter diffraction was used to identify links between heat treatments and microstructure. Subsequently, uniaxial tensile tests were performed to determine the respective tensile properties of all samples. Correlations in the data show a significant loss in strength with respect to an increase in annealing temperature due to grain growth, while no noticeable trend was observed for fracture strain with regard to annealing temperatures.

  20. Assessment of expressions of heat shock protein (HSP 72) and apoptosis after ArF excimer laser ablation of the cornea.

    Science.gov (United States)

    Ishihara, Miya; Sato, Masato; Sato, Shunichi; Arai, Tsunenori; Obara, Minoru; Kikuchi, Makoto

    2004-01-01

    We immunohistochemically studied expressions of inducible heat shock protein 70 (HSP 72) and apoptosis of corneas ablated with an ArF excimer laser. The temperature of corneal surfaces and laser-induced optical emission spectra were measured in real time as direct physical parameters related to the ablation mechanism. To the best of the authors' knowledge, there have been no experimental studies regarding the influence of physical parameters directly related to the ablation mechanism on corneal reactions at the cell level after laser ablation. The expression of HSP 72 was mainly localized in the regenerative epithelium, which was confirmed to be caused by laser ablation. The HSP 72 positive cell ratios had a correlation with thermal dose, which was derived from the measured time courses of temperature. Expressions of both HSP 72 and apoptosis depended on the thermal dose and elapsed time after ablation. HSP 72 and apoptosis could be seen up to a few hundred micrometers into the stroma, only at a fluence with an optical breakdown emission. This could have been caused by shock waves induced by the optical breakdown. (c) 2004 Society of Photo-Optical Instrumentation Engineers.

  1. Heat conduction from the exceedingly hot fiber tip contributes to the endovenous laser ablation of varicose veins

    NARCIS (Netherlands)

    R.R. van den Bos (Renate); M. Kockaert (Michael); H.A.M. Neumann (Martino); R.H. Bremmer (Rolf); T.E.C. Nijsten (Tamar); M.J.C. van Gemert (Martin)

    2009-01-01

    textabstractLower-extremity venous insufficiency is a common condition, associated with considerable health care costs. Endovenous laser ablation is increasingly used as therapy, but its mechanism of action is insufficiently understood. Here, direct absorption of the laser light, collapsing steam

  2. Heat conduction from the exceedingly hot fiber tip contributes to the endovenous laser ablation of varicose veins

    NARCIS (Netherlands)

    van den Bos, R.R.; Kockaert, M.A.; Martino Neumann, H.A.; Bremmer, R.H.; Nijsten, T.; van Gemert, M.J.C.

    2009-01-01

    Lower-extremity venous insufficiency is a common condition, associated with considerable health care costs. Endovenous laser ablation is increasingly used as therapy, but its mechanism of action is insufficiently understood. Here, direct absorption of the laser light, collapsing steam bubbles and

  3. Investigation of Rapid Low-Power Microwave-Induction Heating Scheme on the Cross-Linking Process of the Poly(4-vinylphenol) for the Gate Insulator of Pentacene-Based Thin-Film Transistors.

    Science.gov (United States)

    Fan, Ching-Lin; Shang, Ming-Chi; Wang, Shea-Jue; Hsia, Mao-Yuan; Lee, Win-Der; Huang, Bohr-Ran

    2017-07-03

    In this study, a proposed Microwave-Induction Heating (MIH) scheme has been systematically studied to acquire suitable MIH parameters including chamber pressure, microwave power and heating time. The proposed MIH means that the thin indium tin oxide (ITO) metal below the Poly(4-vinylphenol) (PVP) film is heated rapidly by microwave irradiation and the heated ITO metal gate can heat the PVP gate insulator, resulting in PVP cross-linking. It is found that the attenuation of the microwave energy decreases with the decreasing chamber pressure. The optimal conditions are a power of 50 W, a heating time of 5 min, and a chamber pressure of 20 mTorr. When suitable MIH parameters were used, the effect of PVP cross-linking and the device performance were similar to those obtained using traditional oven heating, even though the cross-linking time was significantly decreased from 1 h to 5 min. Besides the gate leakage current, the interface trap state density (Nit) was also calculated to describe the interface status between the gate insulator and the active layer. The lowest interface trap state density can be found in the device with the PVP gate insulator cross-linked by using the optimal MIH condition. Therefore, it is believed that the MIH scheme is a good candidate to cross-link the PVP gate insulator for organic thin-film transistor applications as a result of its features of rapid heating (5 min) and low-power microwave-irradiation (50 W).

  4. Investigation of Rapid Low-Power Microwave-Induction Heating Scheme on the Cross-Linking Process of the Poly(4-vinylphenol for the Gate Insulator of Pentacene-Based Thin-Film Transistors

    Directory of Open Access Journals (Sweden)

    Ching-Lin Fan

    2017-07-01

    Full Text Available In this study, a proposed Microwave-Induction Heating (MIH scheme has been systematically studied to acquire suitable MIH parameters including chamber pressure, microwave power and heating time. The proposed MIH means that the thin indium tin oxide (ITO metal below the Poly(4-vinylphenol (PVP film is heated rapidly by microwave irradiation and the heated ITO metal gate can heat the PVP gate insulator, resulting in PVP cross-linking. It is found that the attenuation of the microwave energy decreases with the decreasing chamber pressure. The optimal conditions are a power of 50 W, a heating time of 5 min, and a chamber pressure of 20 mTorr. When suitable MIH parameters were used, the effect of PVP cross-linking and the device performance were similar to those obtained using traditional oven heating, even though the cross-linking time was significantly decreased from 1 h to 5 min. Besides the gate leakage current, the interface trap state density (Nit was also calculated to describe the interface status between the gate insulator and the active layer. The lowest interface trap state density can be found in the device with the PVP gate insulator cross-linked by using the optimal MIH condition. Therefore, it is believed that the MIH scheme is a good candidate to cross-link the PVP gate insulator for organic thin-film transistor applications as a result of its features of rapid heating (5 min and low-power microwave-irradiation (50 W.

  5. On demand shape-selective integration of individual vertical germanium nanowires on a Si(111) substrate via laser-localized heating.

    Science.gov (United States)

    Ryu, Sang-Gil; Kim, Eunpa; Yoo, Jae-Hyuck; Hwang, David J; Xiang, Bin; Dubon, Oscar D; Minor, Andrew M; Grigoropoulos, Costas P

    2013-03-26

    Semiconductor nanowire (NW) synthesis methods by blanket furnace heating produce structures of uniform size and shape. This study overcomes this constraint by applying laser-localized synthesis on catalytic nanodots defined by electron beam lithography in order to accomplish site- and shape-selective direct integration of vertically oriented germanium nanowires (GeNWs) on a single Si(111) substrate. Since the laser-induced local temperature field drives the growth process, each NW could be synthesized with distinctly different geometric features. The NW shape was dialed on demand, ranging from cylindrical to hexagonal/irregular hexagonal pyramid. Finite difference time domain analysis supported the tunability of the light absorption and scattering spectra via controlling the GeNW shape.

  6. Rapid identification of pathogens directly from blood culture bottles by Bruker matrix-assisted laser desorption laser ionization-time of flight mass spectrometry versus routine methods.

    Science.gov (United States)

    Jamal, Wafaa; Saleem, Rola; Rotimi, Vincent O

    2013-08-01

    The use of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) for identification of microorganisms directly from blood culture is an exciting dimension to the microbiologists. We evaluated the performance of Bruker SepsiTyper kit™ (STK) for direct identification of bacteria from positive blood culture. This was done in parallel with conventional methods. Nonrepetitive positive blood cultures from 160 consecutive patients were prospectively evaluated by both methods. Of 160 positive blood cultures, the STK identified 114 (75.6%) isolates and routine conventional method 150 (93%). Thirty-six isolates were misidentified or not identified by the kit. Of these, 5 had score of >2.000 and 31 had an unreliable low score of time using the STK was 35 min, including extraction steps and 30:12 to 36:12 h with routine method. The STK holds promise for timely management of bacteremic patients. Copyright © 2013 Elsevier Inc. All rights reserved.

  7. Rapid, single-molecule assays in nano/micro-fluidic chips with arrays of closely spaced parallel channels fabricated by femtosecond laser machining.

    Science.gov (United States)

    Canfield, Brian K; King, Jason K; Robinson, William N; Hofmeister, William H; Davis, Lloyd M

    2014-08-20

    Cost-effective pharmaceutical drug discovery depends on increasing assay throughput while reducing reagent needs. To this end, we are developing an ultrasensitive, fluorescence-based platform that incorporates a nano/micro-fluidic chip with an array of closely spaced channels for parallelized optical readout of single-molecule assays. Here we describe the use of direct femtosecond laser machining to fabricate several hundred closely spaced channels on the surfaces of fused silica substrates. The channels are sealed by bonding to a microscope cover slip spin-coated with a thin film of poly(dimethylsiloxane). Single-molecule detection experiments are conducted using a custom-built, wide-field microscope. The array of channels is epi-illuminated by a line-generating red diode laser, resulting in a line focus just a few microns thick across a 500 micron field of view. A dilute aqueous solution of fluorescently labeled biomolecules is loaded into the device and fluorescence is detected with an electron-multiplying CCD camera, allowing acquisition rates up to 7 kHz for each microchannel. Matched digital filtering based on experimental parameters is used to perform an initial, rapid assessment of detected fluorescence. More detailed analysis is obtained through fluorescence correlation spectroscopy. Simulated fluorescence data is shown to agree well with experimental values.

  8. Rapid Prototyping of Plastic Lab-on-a-Chip by Femtosecond Laser Micromachining and Removable Insert Microinjection Molding

    Directory of Open Access Journals (Sweden)

    Rebeca Martínez Vázquez

    2017-11-01

    Full Text Available We have introduced a new hybrid fabrication method for lab-on-a-chip devices through the combination of femtosecond laser micromachining and removable insert micro-injection molding. This method is particularly suited for the fast prototyping of new devices, while maintaining a competitive low cost. To demonstrate the effectiveness of our approach, we designed, fabricated, and tested a completely integrated flow cytometer coupled to a portable media device. The system operation was tested with fluorescent plastic micro-bead solutions ranging from 100 beads/μL to 500 beads/μL. We demonstrated that this hybrid lab-on-a-chip fabrication technology is suitable for producing low-cost and portable biological microsystems and for effectively bridging the gap between new device concepts and their mass production.

  9. Rapid discrimination of environmental Vibrio by matrix-assisted laser desorption ionization time-of-flight mass spectrometry.

    Science.gov (United States)

    Eddabra, Rkia; Prévost, Gilles; Scheftel, Jean-Michel

    2012-04-20

    The aim of this study was to discriminate 30 Vibrio strains isolated from two wastewater treatment plants from Agadir, Morocco by two molecular typing methods, pulsed-field gel electrophoresis (PFGE) and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Out of the 30 strains of Vibrio examined in this study, 5 isolates could not be typed by PFGE and consistently appeared as a smear on the gel. In general, high genetic biodiversity among the Vibrio strains was found regardless to the isolation source. The results of MALDI TOF analysis show a high congruence of strain grouping demonstrating the accuracy and reliability of MALDI-TOF MS. Copyright © 2011 Elsevier GmbH. All rights reserved.

  10. Novel use of an aerospace selective laser sintering machine for rapid prototyping of an orbital blowout fracture.

    Science.gov (United States)

    Williams, J V; Revington, P J

    2010-02-01

    The authors describe the novel use of a selective laser sintering (SLS) machine, commonly used in the aerospace industry, to produce an accurate model of an orbital blowout fracture. Standard stereolithographic apparatus (SLA) technology failed to reproduce either orbital floor of a patient with a blowout fracture. The use of SLS technology using the same CT dataset to produce a superior model, highlights potential limitations of routine SLA technology and the high accuracy of SLS models. A custom-made titanium implant was constructed by hand using the SLS model as a template, it was positioned surgically and the patient's symptoms resolved uneventfully. Copyright 2009 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

  11. Generation and transport of fast electrons in the interaction of high intensity laser with matter; Generation et transport des electrons rapides dans l'interaction laser-matiere a haut flux

    Energy Technology Data Exchange (ETDEWEB)

    Popescu, H

    2005-10-15

    The general context of this study is the Inertial Confinement for thermonuclear controlled fusion and, more precisely, the Fast Igniter (FI). In this context the knowledge of the generation and transport of fast electrons is crucial. This thesis is an experimental study of the generation and transport of fast electrons in the interaction of a high intensity laser ({>=} 10{sup 19} W/cm{sup 2}) with a solid target. The main diagnostic used here is the transition radiation. This radiation depends on the electrons which produce it and thus it gives important information on the electrons: energy, temperature, propagation geometry, etc. The spectral, temporal and spatial analysis permitted to put in evidence the acceleration of periodic electron bunches which, in this case, emit a Coherent Transition Radiation (CTR). During this thesis we have developed some theoretical models in order to explain the experimental results. We find this way two kinds of electron bunches, emitted either at the laser frequency ({omega}{sub 0}), either at the double of this frequency (2{omega}{sub 0}), involving several acceleration mechanisms: vacuum heating / resonance absorption and Lorentz force, respectively. These bunches are also observed in the PIC (particle-in-cell) simulations. The electron temperature is of about 2 MeV in our experimental conditions. The electrons are emitted starting from a point source (which is the laser focal spot) and then propagate in a ballistic way through the target. In some cases they can be re-injected in the target by the electrostatic field from the target edges. This diagnostic is only sensitive to the coherent relativistic electrons, which explains the weak total energy that they contain (about a few mJ). The CTR signal emitted by those fast electrons is largely dominating the signal emitted by the less energetic electrons, even if they contain the major part of the energy (about 1 J). (author)

  12. Synthesis of Binary Transition Metal Nitrides, Carbides and Borides from the Elements in the Laser-Heated Diamond Anvil Cell and Their Structure-Property Relations

    Science.gov (United States)

    Friedrich, Alexandra; Winkler, Björn; Juarez-Arellano, Erick A.; Bayarjargal, Lkhamsuren

    2011-01-01

    Transition metal nitrides, carbides and borides have a high potential for industrial applications as they not only have a high melting point but are generally harder and less compressible than the pure metals. Here we summarize recent advances in the synthesis of binary transition metal nitrides, carbides and borides focusing on the reaction of the elements at extreme conditions generated within the laser-heated diamond anvil cell. The current knowledge of their structures and high-pressure properties like high-(p,T) stability, compressibility and hardness is described as obtained from experiments. PMID:28824101

  13. Measurements of the K -Shell Opacity of a Solid-Density Magnesium Plasma Heated by an X-Ray Free-Electron Laser

    Science.gov (United States)

    Preston, T. R.; Vinko, S. M.; Ciricosta, O.; Hollebon, P.; Chung, H.-K.; Dakovski, G. L.; Krzywinski, J.; Minitti, M.; Burian, T.; Chalupský, J.; Hájková, V.; Juha, L.; Vozda, V.; Zastrau, U.; Lee, R. W.; Wark, J. S.

    2017-08-01

    We present measurements of the spectrally resolved x rays emitted from solid-density magnesium targets of varying sub-μ m thicknesses isochorically heated by an x-ray laser. The data exhibit a largely thickness-independent source function, allowing the extraction of a measure of the opacity to K -shell x rays within well-defined regimes of electron density and temperature, extremely close to local thermodynamic equilibrium conditions. The deduced opacities at the peak of the K α transitions of the ions are consistent with those predicted by detailed atomic-kinetics calculations.

  14. Data demonstrating the effects of build orientation and heat treatment on fatigue behavior of selective laser melted 17–4 PH stainless steel

    Directory of Open Access Journals (Sweden)

    Aref Yadollahi

    2016-06-01

    Full Text Available Axial fully-reversed strain-controlled (R=−1 fatigue experiments were performed to obtain data demonstrating the effects of building orientation (i.e. vertical versus horizontal and heat treatment on the fatigue behavior of 17–4 PH stainless steel (SS fabricated via Selective Laser Melting (SLM (Yadollahi et al., submitted for publication [1]. This data article provides detailed experimental data including cyclic stress-strain responses, variations of peak stresses during cyclic deformation, and fractography of post-mortem specimens for SLM 17–4 PH SS.

  15. Synthesis of Binary Transition Metal Nitrides, Carbides and Borides from the Elements in the Laser-Heated Diamond Anvil Cell and Their Structure-Property Relations

    Directory of Open Access Journals (Sweden)

    Lkhamsuren Bayarjargal

    2011-09-01

    Full Text Available Transition metal nitrides, carbides and borides have a high potential for industrial applications as they n