Science.gov

Sample records for laser surface cleaning

  1. Laser surface cleaning

    SciTech Connect

    Crivella, E.C.; Freiwald, J.; Freiwald, D.A.

    1996-12-31

    Decontamination of contaminated metal and material recycle, two of 31 priority needs identified by the D&D focus group, are the most promising applications for laser ablation within the DOE complex. F2 Associates has developed a robotic laser ablation system that is capable of high contamination rates, waste volume reduction, surface pore cleaning, and real-time characterization of materials. It is being demonstrated that this system will be the most cost-effective technology for metal decontamination and material recycle.

  2. Laser cleaning of metal surfaces: physical processes and applications

    NASA Astrophysics Data System (ADS)

    Veiko, V. P.; Mutin, T. J.; Smirnov, V. N.; Shakhno, E. A.; Batishche, S. A.

    2008-01-01

    Physical processes occurring by laser cleaning of metal surfaces from soiling particles, coatings and near-surface oxide or corroded layer are considered. Unconventional methods of laser cleaning which promote increasing the quality and effectiveness of cleaning and solving of the problem of soiling substance gathering are proposed. Applications of these methods in a number of novel fields, such as pinholes cleaning, coatings removal, radioactive contaminated layers removal, cleaning of objects of historic and cultural heritage are considered.

  3. Laser shock cleaning of radioactive particulates from glass surface

    NASA Astrophysics Data System (ADS)

    Kumar, Aniruddha; Prasad, Manisha; Bhatt, R. B.; Behere, P. G.; Afzal, Mohd.; Kumar, Arun; Nilaya, J. P.; Biswas, D. J.

    2014-06-01

    Efficient removal of Uranium-di-oxide (UO2) particulates from glass surface was achieved by Nd-YAG laser induced airborne plasma shock waves. The velocity of the generated shock wave was measured by employing the photo-acoustic probe deflection method. Experiments were carried out to study the effect of laser pulse energy, number of laser exposures and the separation between the substrate surface and the onset point of the shock wave on the de-contamination efficiency. The efficacy of the process was estimated monitoring the alpha activity of the samples before and after laser shock cleaning using a ZnS (Ag) scintillation detector. Significant cleaning efficiency could be achieved when the substrate was exposed to multiple laser shocks that could be further improved by geometrically confining the plasma. No visual damage or loss in optical quality was observed when the shock cleaned surfaces were analysed by optical microscopy and spectrophotometry. The area cleaned by laser shock cleaning was found to be significantly larger than that possible by conventional laser cleaning. Theoretical estimate of the shock force generated has been found to exceed the van der Waal`s binding force for spherical contaminant particulate.

  4. Laser Cleaning of Corroded Steel Surfaces: A Comparison with Mechanical Cleaning Methods

    NASA Astrophysics Data System (ADS)

    Koh, Y. S.; Powell, J.; Kaplan, A.; Carlevi, J.

    Conservation often requires the removal of oxide layers from metal artifacts and new cleaning methods are being developed all the time. This paper provides a quantitative comparison of eight cleaning methods, three of which are mechanical (brushing or micro-blasting with Al2O3 or glass beads) and five of which are laser dependent (TEA CO2 or Nd:YAG laser, with or without surface water). Surface profilometry and scanning electron microscopy have been used to compare the cleaned surfaces with the original, known, surface geometries.

  5. Laser Ablation Cleaning of Self-Reacting Friction Stir Weld Seam Surfaces: A Preliminary Evaluation

    NASA Technical Reports Server (NTRS)

    Nunes, A. C., Jr.; Russell, C. K.; Brooke, S. A.; Parry, Q.; Lowrey, N. M.

    2014-01-01

    Anodized aluminum panels were cleaned by three lasers at three separate sites with a view to determining whether more economical laser cleaning might supplant current manual cleaning methods for preparation of surfaces to be welded by the self-reacting friction stir process. Uncleaned panels yielded welds exhibiting residual oxide defect (ROD) and failing at very low stresses along the trace of the weld seam. Manually cleaned panels yielded welds without ROD; these welds failed at nominal stress levels along an angled fracture surface not following the weld seam trace. Laser cleaned panels yielded welds failing at intermediate stress levels. The inadequacy of the laser cleaning processes leaves questions: Was the anodized aluminum test too stringent to represent actual cleaning requirements? Were the wrong laser cleaning techniques/parameters used for the study? Is the laser cleaning mechanism inadequate for effective preweld surface cleaning?

  6. Study of the laser cleaning on plaster sculptures. The effect of laser irradiation on the surfaces

    NASA Astrophysics Data System (ADS)

    Pelosi, C.; Fodaro, D.; Sforzini, L.; Rubino, A. R.; Falqui, A.

    2013-06-01

    The focus of this paper is to study the effects caused by the laser irradiation on nineteenth and twentieth century plaster sculptures. Before applying the laser cleaning on the sculptures, it was tested on samples prepared in laboratory according to the results of the scientific investigation carried out on the selected works of art. The characterization of the surface finishing materials of the sculptures was performed by Fourier Transform Infrared spectrometry (FTIR), X-ray Fluorescence spectroscopy (XRF), UV fluorescence photography, and internal micro stratigraphic analysis. Regarding the finishing materials, shellac, zinc white, siccative oil and proteins were found on the surfaces. The results of the scientific investigation, together with the examination of the ancient technical manuals, were used to create the laboratory samples to carry out the irradiation tests with laser. The laser irradiation and cleaning tests were carried out with a Q-switched Nd:YAG system. The irradiated surfaces were analyzed before and after the laser tests with the aid of a video microscope and a reflectance spectrophotometer, in order to evaluate the color changes of the surfaces. The possible morphological modifications caused by laser irradiation were also investigated by Scanning Electron Microscopy (SEM) together with ancillary Energy Dispersive Spectroscopy (EDS) elemental analysis. Concerning the laser cleaning test on the samples, in general little color changes were observed both with the 532 and 1064 nm wavelength. Total color changes, expressed as Δ E*, are always small apart from the samples made of shellac and zinc white in linseed oil, as finishing layer. As regards these samples the surface irradiated with the laser greyed lightly, corresponding to a decrease of L* parameter (lightness). SEM imaging of the treated and not-treated samples, both at low and high magnification, does not show evidence of significant morphological differences due to the laser beam

  7. A novel laser-based approach for cleaning contaminated metallic surfaces coupled with rapid residue analysis

    NASA Astrophysics Data System (ADS)

    Fox, Robert V.; Roberts, Lauren; DeLucia, Frank C.; Miziolek, Andrzej W.; Whitehouse, Andrew I.

    2013-05-01

    We are developing a novel approach for cleaning and confirming contaminated metallic surfaces that is based on laser ablation to clean the surfaces followed closely in time and space by laser analysis of the degree of cleanliness. Laser-based surface cleaning is a well-established technology and is commercially available (e.g., Adapt-Laser). The new development involves the integration of a LIBS (Laser Induced Breakdown Spectroscopy) surface analytical capability to analyze the surface before and right after the laser cleaning step for the presence or absence of unwanted residues. This all-laser approach is being applied to surfaces of steel vessels that have been used for the containment and destruction of chemical munitions. Various processes used for the destruction of chemical munitions result in the creation of oxidized steel surfaces containing residues (e.g., arsenic, mercury) that need to be removed to acceptable levels. In many instances inorganic molecular contaminants become integrated into oxide layers, necessitating complete removal of the oxide layer to achieve ideal levels of surface cleanliness. The focus of this study is on oxidized steel surfaces exposed to thermally decomposed Lewisite, and thus laden with arsenic. We demonstrate here that a commercially-available cleaning laser sufficiently removes the oxide coating and the targeted contaminants from the affected steel surface. Additionally, we demonstrate that LIBS is useful for the identification of arsenic and mercury on steel surfaces before and after laser cleaning, with arsenic being specifically tracked and analyzed at levels less than 1 microgram per square centimeter surface loading. Recent progress and future directions are presented and discussed.

  8. Comparative study of pulsed laser cleaning applied to weathered marble surfaces

    NASA Astrophysics Data System (ADS)

    Ortiz, P.; Antúnez, V.; Ortiz, R.; Martín, J. M.; Gómez, M. A.; Hortal, A. R.; Martínez-Haya, B.

    2013-10-01

    The removal of unwanted matter from surface stones is a demanding task in the conservation of cultural heritage. This paper investigates the effectiveness of near-infrared (IR) and ultraviolet (UV) laser pulses for the cleaning of surface deposits, iron oxide stains and different types of graffiti (black, red and green sprays and markers, and black cutting-edge ink) on dolomitic white marble. The performance of the laser techniques is compared to common cleaning methods on the same samples, namely pressurized water and chemical treatments. The degree of cleaning achieved with each technique is assessed by means of colorimetric measurements and X-ray microfluorescence. Eventual morphological changes induced on the marble substrate are monitored with optical and electronic microscopy. It is found that UV pulsed laser ablation at 266 nm manages to clean all the stains except the cutting-edge ink, although some degree of surface erosion is produced. The IR laser pulses at 1064 nm can remove surface deposits and black spray acceptably, but a yellowing is observed on the stone surface after treatment. An economic evaluation shows that pulsed laser cleaning techniques are advantageous for the rapid cleaning of small or inaccessible surface areas, although their extensive application becomes expensive due to the long operating times required.

  9. Study on surface properties of gilt-bronze artifacts, after Nd:YAG laser cleaning

    NASA Astrophysics Data System (ADS)

    Lee, Hyeyoun; Cho, Namchul; Lee, Jongmyoung

    2013-11-01

    As numerous pores are formed at plating gilt-bronze artifacts, the metal underlying the gold is corroded and corrosion products are formed on layer of gold. Through this study, the surfaces of gilt-bronze are being investigated before and after the laser irradiation to remove corrosion products of copper by using Nd:YAG laser. For gilt-bronze specimens, laser and chemical cleaning were performed, and thereafter, surface analysis with SEM-EDS, AFM, and XPS were used to determine the surface characteristics. Experimental results show that chemical cleaning removes corrosion products of copper through dissolution but it was not removed uniformly and separated the metal substrate and the gold layer. Nevertheless, through laser cleaning, some of the corrosions were removed with some damaged areas due to certain conditions and brown residues remained. Brown residues were copper corrosion products mixed with soil left within the gilt layer. It was due to surface morphology of uneven and rough gilt layer. Hence, they did not react effectively to laser beams, and thus, remained as residues. The surface properties of gilt-bronze should be thoroughly investigated with various surface analyses to succeed in laser cleaning without damages or residues.

  10. Laser Cleaning of Mirror Surface for Optical Diagnostic Systems of the ITER

    NASA Astrophysics Data System (ADS)

    Gubskii, K.; Kuznetsov, A.; Savchenkov, A.; Andreev, A.; Tugarinov, S.; Buzhinskij, O.

    The development of cleaning optics and deposition-mitigating techniques is a key factor in the construction and operation of optical diagnostics in ITER. The cleaning of optical surface by pulsed radiation from a fiber laser is an effective method that can recover optical properties of the mirror surface. The possibility of cleaning metallic mirrors from films with complex composition by pulsed radiation from a fiber laser has been experimentally researched. It has been shown that high initial reflection characteristics of optical elements can be recovered by choosing regimes of radiation effect on the deposited surface. Efficient cleaning is ensured by radiation with the power density of less than 107 W/cm2. At this relatively low power density, pollutions are removed in a solid phase and the thermal effect on the mirror is insignificant. Preliminary experiments of the metal mirrors cleaning by fiber laser radiation have demonstrated the possibility of hardware implementation techniques. Experiments on transport of laser radiation to the metal mirror by using a system of lens and cleaning showed the possibility of a hardware implementation of methods applicable in the geometry of the port-plug ITER.

  11. How to clean surfaces

    NASA Astrophysics Data System (ADS)

    Bennett, Jean M.

    2004-06-01

    Various cleaning methods are available depending on the sizes of the parts, mounted or unmounted, and purpose of the cleaning. Dust and other particle contamination affect scattering and act as nuclei for defects in optical coatings. In some cases, these defects can initiate laser damage. Noncontact cleaning methods to eliminate particle contamination include blowing large particles from surfaces with an air bulb, "canned air," or a nitrogen gas jet, for a gentle cleaning and CO2 snow for more aggressive particle removal. Laser assisted particle removal is a new high tech method. A strip coating material applied to the surface and subsequently removed will remove large fresh particles and often fingerprints. Contamination films affect the quality and adherence of optical coatings. These are usually removed (from unmounted optics) by cleaning the surface in a detergent and water bath followed by extensive rinsing and non-contact drying. Alternate methods when immersion in water is not possible are drag wiping, or spraying or squirting organic solvents over the surface. Before cleaning, surfaces must be visually inspected to determine the type and location of the contamination, to decide if cleaning is necessary, and what type of cleaning technique to use. Finally, bad cleaning is much worse than no cleaning! Illustrations of the cleaning methods described above will be given.

  12. Method using laser irradiation for the production of atomically clean crystalline silicon and germanium surfaces

    DOEpatents

    Ownby, G.W.; White, C.W.; Zehner, D.M.

    1979-12-28

    This invention relates to a new method for removing surface impurities from crystalline silicon or germanium articles, such as off-the-shelf p- or n-type wafers to be doped for use as junction devices. The principal contaminants on such wafers are oxygen and carbon. The new method comprises laser-irradiating the contaminated surface in a non-reactive atmosphere, using one or more of Q-switched laser pulses whose parameters are selected to effect melting of the surface without substantial vaporization thereof. In a typical application, a plurality of pulses is used to convert a surface region of an off-the-shelf silicon wafer to an atomically clean region. This can be accomplished in a system at a pressure below 10-/sup 8/ Torr, using Q-switched ruber-laser pulses having an energy density in the range of from about 60 to 190 MW/cm/sup 2/.

  13. Method using laser irradiation for the production of atomically clean crystalline silicon and germanium surfaces

    DOEpatents

    Ownby, Gary W.; White, Clark W.; Zehner, David M.

    1981-01-01

    This invention relates to a new method for removing surface impurities from crystalline silicon or germanium articles, such as off-the-shelf p- or n-type wafers to be doped for use as junction devices. The principal contaminants on such wafers are oxygen and carbon. The new method comprises laser-irradiating the contaminated surface in a non-reactive atmosphere, using one or more of Q-switched laser pulses whose parameters are selected to effect melting of the surface without substantial vaporization thereof. In a typical application, a plurality of pulses is used to convert a surface region of an off-the-shelf silicon wafer to an automatically clean region. This can be accomplished in a system at a pressure below 10.sup.-8 Torr, using Q-switched ruby-laser pulses having an energy density in the range of from about 60 to 190 MW/cm.sup.2.

  14. Surface modification during Nd:YAG (1064 nm) pulsed laser cleaning of organic fibrous materials

    NASA Astrophysics Data System (ADS)

    Strlič, Matija; Kolar, Jana; Šelih, Vid-Simon; Marinček, Marko

    2003-02-01

    Formation of yellow chromophores on artificially soiled surfaces of cellulose sheets, rag paper, linen, cotton, wool and silk during Nd:YAG (1064 nm) pulsed laser cleaning was followed using Vis and FTIR diffuse reflectance spectrometry. Content of reducing carbonyl groups and changes in FTIR reflectance spectra of cellulose are indicative of surface chemical modifications typical of thermal degradation at elevated temperatures. Two types of soiling were used: well-characterised natural dust and carbon powder and no difference in laser-induced formation of chromophores on material surface was observed at low deposit densities. The influence of laser fluence and number of repetitions was studied and a single pulse of a higher fluence (1 J cm -1) is in general more advisable. No bleaching of the chromophores formed was noticed after repeated treatments.

  15. Fabrication of superhydrophilic or superhydrophobic self-cleaning metal surfaces using picosecond laser pulses and chemical fluorination

    NASA Astrophysics Data System (ADS)

    Zheng, Buxiang; Jiang, Gedong; Wang, Wenjun; Mei, Xuesong

    2016-05-01

    Bioinspired superhydrophilic/phobic self-cleaning surfaces have recently drawn a lot of interest in both fundamental and applied research. A hybrid method to produce the self-cleaning property of micro/nanostructured surface using ultra-fast laser pulses followed by chemical fluorination is proposed. The typical micro/nanocomposite structures that form from microporous arrays and microgroove groups have been processed by picosecond laser on titanium alloy surface. The surface hydrophilic/phobic and self-cleaning properties of micro/nanostructures before and after fluorination with fluoroalkyl-silane were investigated using surface contact angle measurements. The results indicate that surface properties change from hydrophilic to hydrophobic after fluorination, and the micro/nanostructured surface with increased roughness contributes to the improvement of surface hydrophobicity. The micro/nanomodification can make the original hydrophilic titanium alloy surface more hydrophilic or superhydrophilic. It also can make an originally hydrophobic fluorinated titanium alloy surface more hydrophobic or superhydrophobic. The produced micro/nanostructured titanium alloy surfaces show excellent self-cleaning properties regardless of the fluorination treatment, although the fluorinated surfaces have slightly better self-cleaning properties. It is found that surface treatment using ultra-fast laser pulses and subsequent chemical fluorination is an effective way to manipulate surface wettability and obtain self-cleaning properties.

  16. Dry laser cleaning of mechanically thin films

    NASA Astrophysics Data System (ADS)

    Bloisi, F.; Barone, A. C.; Vicari, L.

    2004-11-01

    Laser-assisted particle removal has acquired a growing importance in last few years, finding applications in several fields ranging from microelectronics to conservation and restoration of materials having cultural or historical interest. Recently new 'indirect' laser cleaning techniques such as 'shock' and 'verso' laser cleaning have been developed. Here we present a simple laser cleaning mechanical model in order to associate cleaning efficiency to surface deformation characteristics during cleaning pulse and apply it to examine the behaviour of 'verso' laser cleaning which has experimentally shown promising results on cellulosic (paper and cotton) materials.

  17. Fiber laser cleaning of metal mirror surfaces for optical diagnostic systems of the ITER

    SciTech Connect

    Kuznetsov, A. P. Alexandrova, A. S.; Buzhinsky, O. I.; Gubskiy, K. L.; Kazieva, T. V.; Savchenkov, A. V.; Tugarinov, S. N.

    2015-12-15

    The results of experimental studies into efficiency of removal of films with a complex composition from metal mirrors by pulsed fiber laser irradiation are presented. It is shown that the initial reflectivity of optical elements can be restored by the selection of modes of irradiation impacting the surface with the sputtered film. Effective cleaning is performed by radiation with a power density lower than 10{sup 7} W/cm{sup 2}. The removal of contaminations at such a relatively low power density occurs in a solid phase, owing to which the thermal effect on the mirror is insignificant.

  18. Fiber laser cleaning of metal mirror surfaces for optical diagnostic systems of the ITER

    NASA Astrophysics Data System (ADS)

    Kuznetsov, A. P.; Alexandrova, A. S.; Buzhinsky, O. I.; Gubskiy, K. L.; Kazieva, T. V.; Savchenkov, A. V.; Tugarinov, S. N.

    2015-12-01

    The results of experimental studies into efficiency of removal of films with a complex composition from metal mirrors by pulsed fiber laser irradiation are presented. It is shown that the initial reflectivity of optical elements can be restored by the selection of modes of irradiation impacting the surface with the sputtered film. Effective cleaning is performed by radiation with a power density lower than 107 W/cm2. The removal of contaminations at such a relatively low power density occurs in a solid phase, owing to which the thermal effect on the mirror is insignificant.

  19. New laser surface treatments: cleaning, derusting, deoiling, depainting, deoxidizing, and degreasing

    NASA Astrophysics Data System (ADS)

    Daurelio, Giuseppe; Chita, Giuseppe; Cinquepalmi, Massimo

    1997-08-01

    Many materials as substrates and surface products have been tested. Typically ferrous (Carbon Steels and Stainless Steels) and non ferrous (Al and Cu metals and its alloys) ones have been employed. Some epoxy, polyurethane, polyester and acrylic paints in different thickness and color have been tested. Many types of the surface rust and oxide on different bulk material have been undertaken to test. Similarly some different types of oils and greases, usually used in industry against the oxidation, have been studied. Anyway many types of dirt, grit, calcareous one and so on, present on industrial components, have been laser cleaned without using solvents, acid baths and other ones. Different types of laser sources have been employed: an axial fast flow, 1.5 KW CO2 c.w. and pulsed laser source, emitting a 10.6 micrometers beam; a portable CO2 laser, c.w. (1 to 25 W) and pulsed (1 to 100 Hz and 400 ms max pulse duration) source, emitting a 10.6 micrometers beam with a multi-articulated seven mirrors guiding device and focussing head; a portable Nd-YAG laser, Q-switched and normal-mode source. 1st harmonic 1.06 micrometers (6 ns pulse duration), 2nd harmonic 532 nm (120 microsecond(s) duration pulse- 1J max per-pulse) wavelengths, multi-articulated seven mirrors beam guiding device, 20 Hz repetition rate. This lets shots with 600 mJ max energy per pulse and 100 MW peak power per-pulse with a very low beam divergence, 0.5 mrad at full angle; a transverse fast flow 2.5 kW CO2 laser.

  20. Mechanisms of laser cleaning

    NASA Astrophysics Data System (ADS)

    Watkins, Kenneth G.

    2000-02-01

    Laser cleaning is growing in importance with the introduction of the Montreal protocol which proposes the long term reduction on environmental and public health grounds in the use of organic solvents such as CFCs that are normally used in industrial cleaning. There is also significant interest in laser cleaning in the conservation of sculptures, paintings and museum objects where the process offers advantages in terms of time saving and the enhancement of the ability to conserve certain artefacts. To date there has been insufficient consideration of the mechanisms involved in laser cleaning and how their understanding could lead to improved control and efficiency of the laser cleaning process. This paper considers an overview of the processes involved and their relevance in the different cleaning situations encountered in practice, mainly in terms of the application short pulse length lasers. The mechanisms to be considered include, (1) photon pressure, (2) selective vaporization, (3) shock waves produced by rapid heating and cooling, (4) evaporation pressure, (5) plasma detonation (spallation), (6) ablation.

  1. Influence of surface laser cleaning combined with substrate preheating on the splat morphology

    NASA Astrophysics Data System (ADS)

    Costil, S.; Liao, H.; Gammoudi, A.; Coddet, C.

    2005-03-01

    The morphology of sprayed splats influences the coating adhesion and properties, which are determined by the spraying parameters. Many studies in this field show that the substrate surface temperature is a very relevant factor for the splat shape: the hypotheses of substrate surface wettability and contamination or adsorption layer on the surfaces are supported by the fact that the near-disk-shaped splat can be obtained by increasing the substrate temperature. In this work, a short-duration pulsed laser was used to ablate the substrate just before powder spraying. This ablation was powerful enough to eliminate the contaminants on the substrate surface and to improve the adhesion. In this study the analyses of NiAl splat morphology on the polished TA6V (Ti-6Al-4V) substrate were carried out using laser ablation with different substrate temperatures and different heating modes: the flame and another laser. Results show that the temperature at which the disk-shaped splat can be obtained decreased dramatically by laser ablation. Moreover, laser ablation combined with another laser increased the adhesion strength of the coatings.

  2. ``Verso'' laser cleaning of mechanically thin films

    NASA Astrophysics Data System (ADS)

    Barone, Alberto; Bloisi, Francesco; Vicari, Luciano

    2003-03-01

    In usual dry laser cleaning of opaque samples, short laser pulses are projected onto the sample surface to be cleaned. Energy transferred from light ejects extraneous particles away from the surface. Laser beam fluence is limited by the damage reached by high temperature that the sample surface can produce. We have experimentally shown that for thin samples, the thermo-elastic wave propagates within the whole sample thickness, thus also the rear surface, while temperature effects are limited to the front surface. Therefore, the proposed "verso" laser cleaning technique (the pulsed laser beam impinges on rear sample surface) can be applied to any opaque "mechanically thin" film and is useful for samples having delicate treatments on the surface to be cleaned (e.g. written paper, painted tiles, magnetic films). We have applied our technique to paper sheets showing that it is possible to efficiently clean the surface without damaging ink marks on it. Using a probe beam deflection (PBD) technique in both direct and reverse configuration we have shown that the "verso" cleaning effect is due to the higher penetration depth of the thermo-elastic wave with respect to the temperature profile propagation.

  3. Development of a laser cleaning method for the first mirror surface of the charge exchange recombination spectroscopy diagnostics on ITER

    NASA Astrophysics Data System (ADS)

    Kuznetsov, A. P.; Buzinskij, O. I.; Gubsky, K. L.; Nikitina, E. A.; Savchenkov, A. V.; Tarasov, B. A.; Tugarinov, S. N.

    2015-12-01

    A set of optical diagnostics is expected for measuring the plasma characteristics in ITER. Optical elements located inside discharge chambers are exposed to an intense radiation load, sputtering due to collisions with energetic atoms formed in the charge transfer processes, and contamination due to recondensation of materials sputtered from different parts of the construction of the chamber. Removing the films of the sputtered materials from the mirrors with the aid of pulsed laser radiation is an efficient cleaning method enabling recovery of the optical properties of the mirrors. In this work, we studied the efficiency of removal of metal oxide films by pulsed radiation of a fiber laser. Optimization of the laser cleaning conditions was carried out on samples representing metal substrates polished with optical quality with deposition of films on them imitating the chemical composition and conditions expected in ITER. It is shown that, by a proper selection of modes of radiation exposure to the surface with a deposited film, it is feasible to restore the original high reflection characteristics of optical elements.

  4. Development of a laser cleaning method for the first mirror surface of the charge exchange recombination spectroscopy diagnostics on ITER

    SciTech Connect

    Kuznetsov, A. P.; Buzinskij, O. I.; Gubsky, K. L.; Nikitina, E. A.; Savchenkov, A. V.; Tarasov, B. A.; Tugarinov, S. N.

    2015-12-15

    A set of optical diagnostics is expected for measuring the plasma characteristics in ITER. Optical elements located inside discharge chambers are exposed to an intense radiation load, sputtering due to collisions with energetic atoms formed in the charge transfer processes, and contamination due to recondensation of materials sputtered from different parts of the construction of the chamber. Removing the films of the sputtered materials from the mirrors with the aid of pulsed laser radiation is an efficient cleaning method enabling recovery of the optical properties of the mirrors. In this work, we studied the efficiency of removal of metal oxide films by pulsed radiation of a fiber laser. Optimization of the laser cleaning conditions was carried out on samples representing metal substrates polished with optical quality with deposition of films on them imitating the chemical composition and conditions expected in ITER. It is shown that, by a proper selection of modes of radiation exposure to the surface with a deposited film, it is feasible to restore the original high reflection characteristics of optical elements.

  5. Characterization of Laser Cleaning of Artworks

    PubMed Central

    Marczak, Jan; Koss, Andrzej; Targowski, Piotr; Góra, Michalina; Strzelec, Marek; Sarzyński, Antoni; Skrzeczanowski, Wojciech; Ostrowski, Roman; Rycyk, Antoni

    2008-01-01

    The main tasks of conservators of artworks and monuments are the estimation and analysis of damages (present condition), object conservation (cleaning process), and the protection of an object against further degradation. One of the physical methods that is becoming more and more popular for dirt removal is the laser cleaning method. This method is non-contact, selective, local, controlled, self-limiting, gives immediate feedback and preserves even the gentlest of relief - the trace of a paintbrush. Paper presents application of different, selected physical sensing methods to characterize condition of works of art as well as laser cleaning process itself. It includes, tested in our laboratories, optical surface measurements (e.g. colorimetry, scatterometry, interferometry), infrared thermography, optical coherent tomography and acoustic measurements for “on-line” evaluation of cleaning progress. Results of laser spectrometry analyses (LIBS, Raman) will illustrate identification and dating of objects superficial layers.

  6. Laser cleaning treatment of burnt paintings

    NASA Astrophysics Data System (ADS)

    Antonopoulou-Athera, N.; Chatzitheodoridis, E.; Doulgerides, M.; Evangelatos, Ch.; Serafetinides, A. A.; Terlixi, A.

    2015-01-01

    Three samples taken from two paintings partly burned by fire are investigated for cleaning with lasers. The paintings belong to the collection of the National Gallery of Athens and were made by the great Greek artist Konstantinos Parthenis. To remove the damaged surface and achieve an acceptable restoration result, the optimum combination of fluence and wavelength are sought. Seven different wavelengths with a set of fluences where used, i.e., the five harmonics of a Nd:YAG laser (1064, 532, 355, 266, and 213 nm), a TEA 10.6 μm CO2 and a free running laser Er:YAG 2.94 μm. Characterization was performed prior and after the cleaning process by optical and electron microscopy and analysis (SEM/BSE EDS), as well as X-Ray Diffraction (XRD). The results of this work indicate that the wavelength in the visible spectrum (532 nm) with fluences between 0.1-0.4J/cm2 show the optimum cleaning. The optical microscopy observation shows that with these laser parameters the burnt layer was preferentially removed, exposing the original colors that Parthenis had used in these paintings. Electron microscopy imaging and chemical analysis revealed that the original texture and materials of these samples are preserved after irradiation. Since the damage varies along the surface of the painting, more experiments should be performed in order to find and optimize the full cleaning and characterization process for the homogeneous cleaning of the whole surface of the painting.

  7. Optodynamic characterization of a laser cleaning process

    NASA Astrophysics Data System (ADS)

    Bregar, Vladimir B.; Mozina, Janez I.

    2001-10-01

    Laser cleaning is an optodynamic process in which the optically induced removal of a liquid or a solid from a substrate is accompanied by a detectable acoustic signal. In our experiments we used both excimer and Q-switched Nd:YAG lasers and we examined both dry and steam laser-cleaning techniques. For the samples we used various metal, glass and marble specimens that were contaminated with particles, rust or a layer of paint. An acoustic wave, produced by the abrupt heating and detachment of the contaminants, was observed with a probe-beam deflection technique. We determined two characteristic parameters: the amplitude and the time-of-flight of the acoustic signal. The decrease of the amplitude and the velocity of propagation, which approaches sonic speed, indicate that the dynamics during the laser-cleaning process progressively weaken. According to this assumption the cleaning process is over when both parameters reach a constant value. If the irradiation with the laser pulses continues, the amplitude begins to rise again and time-of-flight decreases; and this is accompanied by a perceivable surface damage. No amplitude decrease and propagation-time prolongation were observed when the intensity of the incoming laser pulses was above the damage threshold for the particular substrate.

  8. Laser cleaning of paintings: from preliminary investigations to a laser cleaning station

    NASA Astrophysics Data System (ADS)

    Apostol, I.; Damian, V.; Garoi, F.; Iordache, I.; Bojan, M.; Apostol, D.; Morais, P. J.; Postolache, D.; Darida, I.

    2010-11-01

    UV laser beam interaction with painting layers in case of aged mock-ups was investigated and ablation and cleaning thresholds were estimated as a function of each layer and sub-layer composition. Ablation depth measurements as a function of incident laser intensities and subsequent irradiation pulse number was measured with white light interferometry (WLI) and profilometric methods, demonstrating a selectivity of the removal of painting layers from submicrometric domain to micrometric domain as a function of surface cleaning needs. The laser cleaning station was designed and developed after careful evaluation of the irradiation conditions proper to the removal of painting layers. A Q-switched Nd:Yag laser radiation is delivered to the artwork through a mirror system consisting in an articulated arm and a laser head. A complete control of the incident laser parameters was envisaged with the laser remote control interface. The system also comprises diagnosis and monitoring tools for the remote control of the cleaning operation. The prototype is controlled by an integrated interface based on a user-friendly software to perform the available operations (e.g. laser cleaning, LIBS, colorimetry, live color monitoring, multispectral analysis, database management). The user interface is also used to start the treatment of a new work, to review or continue a previously started work.

  9. The soft tissue response to contaminated and cleaned titanium surfaces using CO2 laser, citric acid and hydrogen peroxide. An experimental study in the rat abdominal wall.

    PubMed

    Mouhyi, J; Sennerby, L; Van Reck, J

    2000-04-01

    The soft tissue response to clinically retrieved and decontaminated cover screws was evaluated in a rat model. The cover screws were cleaned by using citric acid, sterile water, hydrogen peroxide and CO2 laser alone or with a combination of these. In addition, decontaminated but not cleaned and unused cover screws were used as negative and positive controls, respectively. After cleaning the cover screws were implanted in the abdominal wall of the rat for 6 weeks. The thickness of the fibrous capsule and the number of macrophages within the capsule were measured by means of light microscopical morphometry. As compared to the negative control, CO2 laser on dry surface, CO2 laser + hydrogen peroxide and the positive control had statistically significant thinner fibrous capsules. As compared to the positive, only laser alone resulted in a similar tissue response. It is concluded that CO2 laser used alone or in combination with hydrogen peroxide may be used clinically for sufficient decontamination of titanium surfaces.

  10. Cleaning of boiler heating surfaces

    SciTech Connect

    Maidanik, M. N.; Vasil'ev, V. V.

    2006-09-15

    Basic methods and facilities for the external cleaning of the heating surfaces of boilers designed for the combustion of low-grade solid fuels are discussed. Water and steam blastings, which are the basic means of cleaning furnace shields, and semi-radiative and convective heating surfaces have the greatest range of application.

  11. Characterization of laser-induced plasmas associated with energetic laser cleaning of metal particles on fused silica surfaces.

    PubMed

    Harris, Candace D; Shen, Nan; Rubenchik, Alexander M; Demos, Stavros G; Matthews, Manyalibo J

    2015-11-15

    Time-resolved plasma emission spectroscopy was used to characterize the energy coupling and temperature rise associated with single, 10-ns pulsed laser ablation of metallic particles bound to transparent substrates. Plasma associated with Fe(I) emission lines originating from steel microspheres was observed to cool from >24,000 to ~15,000 K over ~220 ns as τ(-0.28), consistent with radiative losses and adiabatic gas expansion of a relatively free plasma. Simultaneous emission lines from Si(II) associated with the plasma etching of the SiO(2) substrate were observed yielding higher plasma temperatures, ~35,000 K, relative to the Fe(I) plasma. The difference in species temperatures is consistent with plasma confinement at the microsphere-substrate interface as the particle is ejected, and is directly visualized using pump-probe shadowgraphy as a function of pulsed laser energy. PMID:26565837

  12. Characterization of laser-induced plasmas associated with energetic laser cleaning of metal particles on fused silica surfaces.

    PubMed

    Harris, Candace D; Shen, Nan; Rubenchik, Alexander M; Demos, Stavros G; Matthews, Manyalibo J

    2015-11-15

    Time-resolved plasma emission spectroscopy was used to characterize the energy coupling and temperature rise associated with single, 10-ns pulsed laser ablation of metallic particles bound to transparent substrates. Plasma associated with Fe(I) emission lines originating from steel microspheres was observed to cool from >24,000 to ~15,000 K over ~220 ns as τ(-0.28), consistent with radiative losses and adiabatic gas expansion of a relatively free plasma. Simultaneous emission lines from Si(II) associated with the plasma etching of the SiO(2) substrate were observed yielding higher plasma temperatures, ~35,000 K, relative to the Fe(I) plasma. The difference in species temperatures is consistent with plasma confinement at the microsphere-substrate interface as the particle is ejected, and is directly visualized using pump-probe shadowgraphy as a function of pulsed laser energy.

  13. Nd:YAG laser cleaning of ablation debris from excimer-laser-ablated polyimide

    NASA Astrophysics Data System (ADS)

    Gu, Jianhui; Low, Jason; Lim, Puay K.; Lim, Pean

    2001-10-01

    In the processing of excimer laser ablation of nozzles on polyimide in air, both gases like CO2, CO and HCN and solid debris including C2 approximately C12 are produced in laser ablation area. In this paper, we reported for the first time a Nd:YAG laser cleaning of ablation debris generated in excimer laser ablation of polyimide. It demonstrated effective cleaning with the advantages of shortening cleaning cycle time and simplifying cleaning process. The laser used for the cleaning was a Q-switched and frequency doubled Nd:YAG laser with wavelength of 532 nm and repetition rate of 10 Hz. The laser cleaning effect was compared with conventional plasma ashing. AFM measurement showed that the Nd:YAG laser cleaning had no damage to the substrate. XPS results indicated that the polyimide surface cleaned with laser beam had a lower oxygen/carbon ratio than that of plasma ashing. The study shows that frequency doubled Nd:YAG laser cleaning is effective in ablation debris removal from excimer laser ablated polyimide.

  14. Paper surface modification by lasers

    NASA Astrophysics Data System (ADS)

    Zekou, E.; Kotsifaki, D. G.; Serafetinides, A. A.

    2010-10-01

    Lasers can provide a precious tool to conservation process due to their accuracy and the controlled energy they deliver, especially to fragile organic material such as paper. The current study concerns laser modification such as paper cleaning, initially of test papers artificially soiled and then of an original book of the early 20th Century. The test objects were A4 copier paper, newspaper, and paper Whatman No.1056. During the experiments, ink of a pen, pencil and ink from a stamp was mechanically employed on each paper surface. Laser cleaning was applied using a Q-switched Nd:YAG operating at 532 nm and CO2 laser at 10.6 μm for various fluences. The experimental results were presented by using optical microscopy. Eventually, laser cleaning of ink was performed to a book of 1934, by choosing the best conditions and parameters from cleaning the test samples, like Nd:YAG laser operating at 532 nm.

  15. METHOD OF CLEANING METAL SURFACES

    DOEpatents

    Winkler, H.W.; Morfitt, J.W.; Little, T.H.

    1959-05-19

    Cleaning fluids for removing deposits from metal surfaces are described. The cleaning agents of the invention consist of aqueous nitric acid and an amhydrous nitrate salt of a metal which is lower in the electromotive series than the element of the deposit to be removed. In general, the salt content of thc cleaning agents ranged from 10 to 90%, preferably from 10 to 40% by weight; and the balance of the composition comprises nitric acid of any strength from extremely dilute up to concentrated strength.

  16. Energetic laser cleaning of metallic particles and surface damage on silica optics: investigation of the underlying mechanisms

    NASA Astrophysics Data System (ADS)

    Shen, Nan; Demos, Stavros G.; Negres, Raluca A.; Rubenchik, Alexander M.; Harris, Candace D.; Matthews, Manyalibo J.

    2015-11-01

    Surface particulate contamination on optics can lead to laser-induced damage hence limit the performance of high power laser system. In this work we focus on understanding the fundamental mechanisms that lead to damage initiation by metal contaminants. Using time resolved microscopy and plasma spectroscopy, we studied the dynamic process of ejecting ~30 μm stainless steel particles from the exit surface of fused silica substrate irradiated with 1064 nm, 10 ns and 355 nm, 8 ns laser pulses. Time-resolved plasma emission spectroscopy was used to characterize the energy coupling and temperature rise associated with single, 10-ns pulsed laser ablation of metallic particles bound to transparent substrates. Plasma associated with Fe(I) emission lines originating from steel microspheres was observe to cool from <24,000 K to ~15,000 K over ~220 ns as τ-0.22, consistent with radiative losses and adiabatic gas expansion of a relatively free plasma. Simultaneous emission lines from Si(II) associated with the plasma etching of the SiO2 substrate were observed yielding higher plasma temperatures, ~35,000 K, relative to the Fe(I) plasma. The difference in species temperatures is consistent with plasma confinement at the microsphere-substrate interface as the particle is ejected, and is directly visualized using pump-probe shadowgraphy as a function of pulsed laser energy.

  17. Laser cleaning of 19th century Congo rattan mats

    NASA Astrophysics Data System (ADS)

    Carmona, N.; Oujja, M.; Roemich, H.; Castillejo, M.

    2011-09-01

    There is a growing interest by art conservators for laser cleaning of organic materials, such as wooden artworks, paper and textiles, since traditional cleaning with solvents can be a source of further decay and mechanical cleaning may be too abrasive for sensitive fibers. In this work we present a successful laser cleaning approach for 19th century rattan mats from the Brooklyn Museum collection of African Art, now part of the study collection at the Conservation Center in New York. Tests were carried out using the fundamental (1064 nm) and second harmonic (532 nm) wavelength of a Q-switched Nd:YAG laser to measure threshold values both for surface damage and color changes for different types of rattan samples. The irradiated substrates were investigated by optical microscopy, scanning electron microscopy and by UV-vis spectroscopy in order to determine the efficiency of laser cleaning and to assess possible deterioration effects that may have occurred as a result of laser irradiation. The study showed that by using the laser emission at 532 nm, a wavelength for which photon energy is below the bond dissociation level of the main cellulosic compounds and the water absorption is negligible, it is possible to select a range of laser fluences to remove the black dust layer without damaging the rattan material.

  18. Ultrasonic cleaning of interior surfaces

    DOEpatents

    Odell, D. MacKenzie C.

    1996-01-01

    An ultrasonic cleaning method for cleaning the interior surfaces of tubes. The method uses an ultrasonic generator and reflector each coupled to opposing ends of the open-ended, fluid-filled tube. Fluid-tight couplings seal the reflector and generator to the tube, preventing leakage of fluid from the interior of the tube. The reflector and generator are operatively connected to actuators, whereby the distance between them can be varied. When the distance is changed, the frequency of the sound waves is simultaneously adjusted to maintain the resonant frequency of the tube so that a standing wave is formed in the tube, the nodes of which are moved axially to cause cavitation along the length of the tube. Cavitation maximizes mechanical disruption and agitation of the fluid, dislodging foreign material from the interior surface.

  19. Ultrasonic cleaning of interior surfaces

    DOEpatents

    Odell, D. MacKenzie C.

    1994-01-01

    An ultrasonic cleaning apparatus for cleaning the interior surfaces of tubes. The apparatus includes an ultrasonic generator and reflector each coupled to opposing ends of the open-ended, fluid-filled tube. Fluid-tight couplings seal the reflector and generator to the tube, preventing leakage of fluid from the interior of the tube. The reflector and generator are operatively connected to actuators, whereby the distance between them can be varied. When the distance is changed, the frequency of the sound waves is simultaneously adjusted to maintain the resonant frequency of the tube so that a standing wave is formed in the tube, the nodes of which are moved axially to cause cavitation along the length of the tube. Cavitation maximizes mechanical disruption and agitation of the fluid, dislodging foreign material from the interior surface.

  20. Ultrasonic cleaning of interior surfaces

    DOEpatents

    MacKenzie, D.; Odell, C.

    1994-03-01

    An ultrasonic cleaning apparatus is described for cleaning the interior surfaces of tubes. The apparatus includes an ultrasonic generator and reflector each coupled to opposing ends of the open-ended, fluid-filled tube. Fluid-tight couplings seal the reflector and generator to the tube, preventing leakage of fluid from the interior of the tube. The reflector and generator are operatively connected to actuators, whereby the distance between them can be varied. When the distance is changed, the frequency of the sound waves is simultaneously adjusted to maintain the resonant frequency of the tube so that a standing wave is formed in the tube, the nodes of which are moved axially to cause cavitation along the length of the tube. Cavitation maximizes mechanical disruption and agitation of the fluid, dislodging foreign material from the interior surface. 3 figures.

  1. Laser cleaning in the process of electronic device production

    NASA Astrophysics Data System (ADS)

    Apostol, Ion G.; Ulieru, Dumitru G.; Dabu, Razvan V.; Ungureanu, Constantin; Rusen, L.

    2002-08-01

    Due to the continuous technological development in microelectronics and generally in precise materials micromachining there is a continuous need to develop more effective techniques to clean impurities from the surface. Current cleaning techniques used in microelectric devices fabrication lines have an integrated action on the whole surface or on a great part of it, are polluting the ambient and are not efficient for submicron particles. Due to this needs we have studied laser cleaning of silicon wafers with regards to direct applications in semiconductor manufacturing. We have analyzed the ablation effect of laser radiation of 1.06 micrometers on different materials currently used in microelectronic industry and the cleaning effect on a silicon support.

  2. Diode laser potential in laser cleaning of stones

    NASA Astrophysics Data System (ADS)

    Salimbeni, Renzo; Pini, Roberto; Siano, Salvatore; Bachmann, Friedrich G.; Meyer, Frank

    2001-10-01

    In this work we investigated for the first time the laser cleaning process of encrusted stones by employing a high power diode laser system. The test have been carried out using a Rofin-Sinar mod. DL025S emitting up to 2.5 kW CW power to clean various samples representing natural encrustation by pollution exposition and graffiti, typically encountered on historical monuments and buildings in urban environment.

  3. Laser-induced backside wet cleaning technique for glass substrates

    NASA Astrophysics Data System (ADS)

    Weng, Tsu-Shien; Tsai, Chwan-Huei

    2014-08-01

    The aim of this paper is to study the laser-induced backside wet cleaning techniques for glass substrates. Two kinds of laser cleaning techniques are proposed in this study. The first involves applying an Nd:YAG laser to the backside of the substrate which is submerged in water. A metal plate is placed below the glass substrate. Most of the laser energy will be absorbed by the metal plate. The metal then vaporizes the water and generates a turbulent bubble flow. The bubble flow removes the alumina particles from the surface of the glass substrate. The second involves using a CO2 laser to generate turbulent bubble flow to remove the particles. Both methods were successfully demonstrated for the removal of submicron particles of 0.5 μm in size. The phenomena of bubble generation and diffusion are presented in the paper. Because the laser is applied to the backside of the substrate, the damage due to the laser heat can be significantly reduced. The quality and efficient of the backside processing is better than those of the front side processing. The proposed techniques have great potential to provide an improved solution for glass cleaning.

  4. Laser cleaning of ITER's diagnostic mirrors

    NASA Astrophysics Data System (ADS)

    Skinner, C. H.; Gentile, C. A.; Doerner, R.

    2012-10-01

    Practical methods to clean ITER's diagnostic mirrors and restore reflectivity will be critical to ITER's plasma operations. We report on laser cleaning of single crystal molybdenum mirrors coated with either carbon or beryllium films 150 - 420 nm thick. A 1.06 μm Nd laser system provided 220 ns pulses at 8 kHz with typical power densities of 1-2 J/cm^2. The laser beam was fiber optically coupled to a scanner suitable for tokamak applications. The efficacy of mirror cleaning was assessed with a new technique that combines microscopic imaging and reflectivity measurements [1]. The method is suitable for hazardous materials such as beryllium as the mirrors remain sealed in a vacuum chamber. Excellent restoration of reflectivity for the carbon coated Mo mirrors was observed after laser scanning under vacuum conditions. For the beryllium coated mirrors restoration of reflectivity has so far been incomplete and modeling indicates that a shorter duration laser pulse is needed. No damage of the molybdenum mirror substrates was observed.[4pt][1] C.H. Skinner et al., Rev. Sci. Instrum. at press.

  5. Nano and microparticles emission during laser cleaning of stone

    NASA Astrophysics Data System (ADS)

    Ostrowski, Roman; Marczak, Jan; Strzelec, Marek; Barcikowski, Stephan

    2007-02-01

    Air contaminants which emerge during laser ablation often cause health risks if released in the workplace and decrease laser cleaning efficiency if redeposited at the material surface. In addition, ultra-fine particles are generated if short laser pulses are applied. Consequently, a description of the nano and microparticle aerosol generation and the influence of the laser parameters, such as fluence and pulse energy, and type of material surface on the particle size distribution is given in the presented paper. The conducted experiments have shown that for applied laser fluences almost 80% of all emitted particles are in the nanoparticle size range of 30 - 100 nm. The high respirability of such particles can pose health risks, so suitable capture systems near to the processing zone or personal protective equipment such as respiratory masks are required.

  6. Cleaning laser spark spectroscopy for online cleaning quality control method development

    NASA Astrophysics Data System (ADS)

    Mutin, T. Y.; Smirnov, V. N.; Veiko, V. P.; Volkov, S. A.

    2010-07-01

    This work is dedicated to spectroscopic investigations of laser spark during the laser cleaning process. The goal is to proof its analytical possibilities for chemical composition determination for online cleaning quality control. Photographic recordings of laser spark were performed to estimate its parameters. Fiber spectrometer was used to analyze the emission of cleaning process established with fiber laser. Conclusions have been made about fiber laser radiation usability for spectroscopic purpose.

  7. Cleaning laser spark spectroscopy for online cleaning quality control method development

    NASA Astrophysics Data System (ADS)

    Mutin, T. Y.; Smirnov, V. N.; Veiko, V. P.; Volkov, S. A.

    2011-02-01

    This work is dedicated to spectroscopic investigations of laser spark during the laser cleaning process. The goal is to proof its analytical possibilities for chemical composition determination for online cleaning quality control. Photographic recordings of laser spark were performed to estimate its parameters. Fiber spectrometer was used to analyze the emission of cleaning process established with fiber laser. Conclusions have been made about fiber laser radiation usability for spectroscopic purpose.

  8. Bio-Inspired Self-Cleaning Surfaces

    NASA Astrophysics Data System (ADS)

    Liu, Kesong; Jiang, Lei

    2012-08-01

    Self-cleaning surfaces have drawn a lot of interest for both fundamental research and practical applications. This review focuses on the recent progress in mechanism, preparation, and application of self-cleaning surfaces. To date, self-cleaning has been demonstrated by the following four conceptual approaches: (a) TiO2-based superhydrophilic self-cleaning, (b) lotus effect self-cleaning (superhydrophobicity with a small sliding angle), (c) gecko setae-inspired self-cleaning, and (d) underwater organisms-inspired antifouling self-cleaning. Although a number of self-cleaning products have been commercialized, the remaining challenges and future outlook of self-cleaning surfaces are also briefly addressed. Through evolution, nature, which has long been a source of inspiration for scientists and engineers, has arrived at what is optimal. We hope this review will stimulate interdisciplinary collaboration among material science, chemistry, biology, physics, nanoscience, engineering, etc., which is essential for the rational design and reproducible construction of bio-inspired multifunctional self-cleaning surfaces in practical applications.

  9. Laser cleaning of diagnostic mirrors from tungsten-oxygen tokamak-like contaminants

    NASA Astrophysics Data System (ADS)

    Maffini, A.; Uccello, A.; Dellasega, D.; Passoni, M.

    2016-08-01

    This paper presents a laboratory-scale experimental investigation about the laser cleaning of diagnostic first mirrors from tokamak-like contaminants, made of oxidized tungsten compounds with different properties and morphology. The re-deposition of contaminants sputtered from a tokamak first wall onto first mirrors’ surfaces could dramatically decrease their reflectivity in an unacceptable way for the proper functioning of plasma diagnostic systems. The laser cleaning technique has been proposed as a solution to tackle this issue. In this work, pulsed laser deposition was exploited to produce rhodium films functional as first mirrors and to deposit onto them contaminants designed to be realistic in reproducing materials expected to be re-deposited on first mirrors in a tokamak environment. The same laser system was also used to perform laser cleaning experiments, exploiting a sample handling procedure that allows one to clean some cm2 in a few minutes. Cleaning effectiveness was evaluated in terms of specular reflectance recovery and mirror surface integrity. The effect of different laser wavelengths (λ =1064 , 266 nm) on the cleaning process was also addressed, as well as the impact of multiple contamination/cleaning cycles on the process outcome. A satisfactory recovery of pristine mirror reflectance (⩾90%) was obtained in the vis-NIR spectral range, avoiding at the same time mirror damaging. The results here presented show the potential of the laser cleaning technique as an attractive solution for the cleaning of diagnostic first mirrors.

  10. Laser cleaning of diagnostic mirrors from tungsten–oxygen tokamak-like contaminants

    NASA Astrophysics Data System (ADS)

    Maffini, A.; Uccello, A.; Dellasega, D.; Passoni, M.

    2016-08-01

    This paper presents a laboratory-scale experimental investigation about the laser cleaning of diagnostic first mirrors from tokamak-like contaminants, made of oxidized tungsten compounds with different properties and morphology. The re-deposition of contaminants sputtered from a tokamak first wall onto first mirrors’ surfaces could dramatically decrease their reflectivity in an unacceptable way for the proper functioning of plasma diagnostic systems. The laser cleaning technique has been proposed as a solution to tackle this issue. In this work, pulsed laser deposition was exploited to produce rhodium films functional as first mirrors and to deposit onto them contaminants designed to be realistic in reproducing materials expected to be re-deposited on first mirrors in a tokamak environment. The same laser system was also used to perform laser cleaning experiments, exploiting a sample handling procedure that allows one to clean some cm2 in a few minutes. Cleaning effectiveness was evaluated in terms of specular reflectance recovery and mirror surface integrity. The effect of different laser wavelengths (λ =1064 , 266 nm) on the cleaning process was also addressed, as well as the impact of multiple contamination/cleaning cycles on the process outcome. A satisfactory recovery of pristine mirror reflectance (⩾90%) was obtained in the vis–NIR spectral range, avoiding at the same time mirror damaging. The results here presented show the potential of the laser cleaning technique as an attractive solution for the cleaning of diagnostic first mirrors.

  11. Investigation of laser cleaning on bronze cultural relics

    NASA Astrophysics Data System (ADS)

    Ling, Xiulan; Wang, Gao; Zhang, Chen

    2016-05-01

    The effects of laser cleaning on the corrosion layers of bronze cultural relics were studied using a pulsed fiber laser. The laser cleaning threshold value of the corrosion layers was obtained. It was found that the corrosion layer was removed successfully by employing a laser fluence value of 0.32 J cm-2 and scanning for three times. To obtain experimental evidence, laser con-focal scanning microscopy, scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), laser induced breakdown spectroscopy (LIBS) and laser Raman spectroscopy were employed to investigate the cleaning efficiency of corrosion layers on specimens.

  12. Shear stress cleaning for surface departiculation

    NASA Technical Reports Server (NTRS)

    Musselman, R. P.; Yarbrough, T. W.

    1986-01-01

    A cleaning technique widely used by the nuclear utility industry for removal of radioactive surface contamination has proven effective at removing non-hazardous contaminant particles as small as 0.1 micrometer. The process employs a controlled high velocity liquid spray inside a vapor containment enclosure to remove particles from a surface. The viscous drag force generated by the cleaning fluid applies a shear stress greater than the adhesion force that holds small particles to a substrate. Fluid mechanics and field tests indicate general cleaning parameters.

  13. Cathodic ARC surface cleaning prior to brazing

    SciTech Connect

    Dave, V. R.; Hollis, K. J.; Castro, R. G.; Smith, F. M.; Javernick, D. A.

    2002-01-01

    Surface cleanliness is one the critical process variables in vacuum furnace brazing operations. For a large number of metallic components, cleaning is usually accomplished either by water-based alkali cleaning, but may also involve acid etching or solvent cleaning / rinsing. Nickel plating may also be necessary to ensure proper wetting. All of these cleaning or plating technologies have associated waste disposal issues, and this article explores an alternative cleaning process that generates minimal waste. Cathodic arc, or reserve polarity, is well known for welding of materials with tenacious oxide layers such as aluminum alloys. In this work the reverse polarity effect is used to clean austenitic stainless steel substrates prior to brazing with Ag-28%Cu. This cleaning process is compared to acid pickling and is shown to produce similar wetting behavior as measured by dynamic contact angle experiments. Additionally, dynamic contact angle measurements with water drops are conducted to show that cathodic arc cleaning can remove organic contaminants as well. The process does have its limitations however, and alloys with high titanium and aluminum content such as nickel-based superalloys may still require plating to ensure adequate wetting.

  14. Enhanced efficiency of laser shock cleaning process by geometrical confinement of laser-induced plasma

    SciTech Connect

    Jang, Deoksuk; Oh, Joon Ho; Kim, Dongsik; Lee, Jong-Myoung

    2009-07-01

    Surface cleaning based on the laser-induced breakdown of gas and subsequent plasma and shock wave generation can remove small particles from solid surfaces. Accordingly, several studies were performed to expand the cleaning capability of the process. In this work, the cleaning process using laser-induced plasma (LIP) under geometrical confinement is analyzed both theoretically and experimentally. Two-dimensional numerical analysis is conducted to examine the behavior of the LIP shock wave under geometrical confinement for several geometries. As a result of the analysis, we propose a simple and practical method to amplify the intensity of laser-induced shock. In the proposed method, a flat quartz plate placed close to the focal point of the laser pulse confines the expansion of the LIP, allowing the plasma to expand only in one direction. As a consequence of the plasma confinement, the intensity of the shock wave produced is increased significantly. Experiments demonstrate that the enhanced shock wave can remove smaller particles from the surface better than the existing process.

  15. Multifunctional surfaces produced by femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Vorobyev, A. Y.; Guo, Chunlei

    2015-01-01

    In this study, we create a multifunctional metal surface by producing a hierarchical nano/microstructure with femtosecond laser pulses. The multifunctional surface exhibits combined effects of dramatically enhanced broadband absorption, superhydrophobicity, and self-cleaning. The superhydrophobic effect is demonstrated by a falling water droplet repelled away from a structured surface with 30% of the droplet kinetic energy conserved, while the self-cleaning effect is shown by each water droplet taking away a significant amount of dust particles on the altered surface. The multifunctional surface is useful for light collection and water/dust repelling.

  16. Self-cleaning surfaces--virtual realities.

    PubMed

    Blossey, Ralf

    2003-05-01

    In the 19th century, Oscar Wilde stated "We live, I regret to say, in an age of surfaces". Today, we do so even more, and we do not regret it: key advances in the understanding and fabrication of surfaces with controlled wetting properties are about to make the dream of a contamination-free (or 'no-clean') surface come true. Two routes to self-cleaning are emerging, which work by the removal of dirt by either film or droplet flow. Although a detailed understanding of the mechanisms underlying the behaviour of liquids on such surfaces is still a basic research topic, the first commercial products in the household-commodity sector and for applications in biotechnology are coming within reach of the marketplace. This progress report describes the current status of understanding of the underlying mechanisms, the concepts for making such surfaces, and some of their first applications.

  17. Self-cleaning surfaces - virtual realities

    NASA Astrophysics Data System (ADS)

    Blossey, Ralf

    2003-05-01

    In the 19th century, Oscar Wilde stated ``We live, I regret to say, in an age of surfaces''. Today, we do so even more, and we do not regret it: key advances in the understanding and fabrication of surfaces with controlled wetting properties are about to make the dream of a contamination-free (or 'no-clean') surface come true. Two routes to self-cleaning are emerging, which work by the removal of dirt by either film or droplet flow. Although a detailed understanding of the mechanisms underlying the behaviour of liquids on such surfaces is still a basic research topic, the first commercial products in the household-commodity sector and for applications in biotechnology are coming within reach of the marketplace. This progress report describes the current status of understanding of the underlying mechanisms, the concepts for making such surfaces, and some of their first applications.

  18. Method for cleaning and passivating a metal surface

    NASA Technical Reports Server (NTRS)

    Alexander, George B. (Inventor); Carpenter, Norman F. (Inventor)

    1976-01-01

    A cleaning solvent useful in the cleaning of metal surfaces, e.g. nickle-iron alloys, contains sulfamic acid, citric acid, a solvent for hydrocarbon residues, and a surfactant. Metal surfaces are cleaned by contacting the surface with the cleaning solvent and then passivated by contact with aqueous solutions of citric acid or sodium nitrite or a combination of the two.

  19. Photocatalytic Solutions Create Self-Cleaning Surfaces

    NASA Technical Reports Server (NTRS)

    2013-01-01

    A Stennis Space Center researcher investigating the effectiveness of photocatalytic materials for keeping the Center's buildings free of grime turned to a solution created by PURETi Inc. of New York City. Testing proved successful, and NASA and the company now share a Dual Use Technology partnership. PURETi's coatings keep surfaces clean and purify surrounding air, eliminating pollution, odors, and microbes.

  20. Laser cleaning experiences on sculptures' materials: terracotta, plaster, wood, and wax

    NASA Astrophysics Data System (ADS)

    Pelosi, Claudia; Fodaro, D.; Sforzini, Livia; Lo Monaco, Angela

    2013-11-01

    The focus of this paper is to show the work experiences with laser cleaning on sculptures made of terracotta, plaster, wood and wax. These materials exhibit peculiar features that often prevent the use of traditional cleaning procedures to remove the surface dirt, soot or carbonaceous deposits and other materials coming from environment or ancient conservative interventions. To overcome the difficulties in the cleaning of the above mentioned materials, laser technology was tested. The laser irradiation and cleaning tests were carried out with a Q-switched Nd:YAG system under the following conditions: wavelength 1064 nm and 532 nm; energy 4-28 mJ; pulse duration 10 ns; spot diameter 2-8 mm; frequency 5 Hz. The irradiated surfaces were analyzed before and after the laser tests, with the aid of a video microscope and a reflectance spectrophotometer, in order to evaluate the morphology and colour changes of the surfaces. Before starting with the cleaning intervention, some diagnostic analysis was performed on the sculptures in order to obtain the identification of the original materials and of the surface deposits. Concerning this, Fourier Transform Infrared spectroscopy, X-ray fluorescence spectroscopy, and internal micro stratigraphic analysis were performed. This research demonstrated that the laser cleaning is an effective method to remove the surface deposits preserving the original patina of the sculptures and the opacity of the wax. The results gathered in this work encourage to continue the research in order to better understand the interactions between the laser beam and the surfaces and to find the most appropriate laser conditions to clean the sculptures.

  1. Aluminum Surface Texturing by Means of Laser Interference Metallurgy

    SciTech Connect

    Chen, Jian; Sabau, Adrian S; Jones, Jonaaron F.; Hackett, Alexandra C.; Daniel, Claus; Warren, Charles David

    2015-01-01

    The increasing use of lightweight materials, such as aluminum alloys, in auto body structures requires more effective surface cleaning and texturing techniques to improve the quality of the structural components. The present work introduces a novel surface treatment method using laser interferometry produced by two beams of a pulsed Nd:YAG laser operating at 10Hz of frequency to clean aluminum surfaces, and meanwhile creating periodic and rough surface structures. The influences of beam size, laser fluence, wavelength, and pulse number per spot are investigated. High resolution optical profiler images reveal the change of the peak-to-valley height on the laser-treated surface.

  2. Novel Laser Ablation Technology for Surface Decontamination

    SciTech Connect

    Cheng, Chung H.

    2004-06-01

    Laser ablation for surface cleaning has been pursued for the removal of paint on airplanes. It has also been pursued for the cleaning of semiconductor surfaces. However, all these approaches have been pursued by laser ablation in air. For highly contaminated surface, laser ablation in air can easily cause secondary contamination. Thus it is not suitable to apply to achieve surface decontamination for DOE facilities since many of these facilities have radioactive contaminants on the surface. Any secondary contamination will be a grave concern. The objective of this project is to develop a novel technology for laser ablation in liquid for surface decontamination. It aims to achieve more efficient surface decontamination without secondary contamination and to evaluate the economic feasibility for large scale surface decontamination with laser ablation in liquid. When laser ablation is pursued in the solution, all the desorbed contaminants will be confined in liquid. The contaminants can be precipitated and subsequently contained in a small volume for disposal. It can reduce the risk of the decontamination workers. It can also reduce the volume of contaminants dramatically.

  3. Behavior of Al on Clean and Oxidized GaAs(110) Surfaces

    NASA Astrophysics Data System (ADS)

    Kim, Hyunwoo

    1993-04-01

    The adsorption of Al on clean and oxidized GaAs(110) surfaces was studied. The characteristics of an oxide surface formed in vacuum and during the chemical etching process of the tip have been investigated using the field desorption (FD) cleaning method and the retarding potential analyzer (RPA) equipped with an argon laser. The results obtained for the FD clean surface and on the oxidized surface are discussed in terms of the RPA threshold and work function change. The oxide films formed at relatively low temperatures on the GaAs(110) surface can easily be desorbed by FD. The intrinsic potential drops across the oxide surface disappear suddenly at a certain field value. This may indicate that the desorbed surface region is composed of a metallic species such as Ga. Changes in work function are observed but there is no change in the threshold values (Vth) with deposition of Al on the field-desorbed clean surface. The thick layers of Al on the oxidized surface completely cancel the effect of oxide on Vth, which decreases to the value of a metallic clean surface. In addition, the value of Vth decreases dramatically to that of a metallic clean surface by absorption of the laser beam on the oxidized surface, whereas only the thermal effect is seen on a metallic clean surface.

  4. Surface modifications induced by pulsed-laser texturing—Influence of laser impact on the surface properties

    NASA Astrophysics Data System (ADS)

    Costil, S.; Lamraoui, A.; Langlade, C.; Heintz, O.; Oltra, R.

    2014-01-01

    Laser cleaning technology provides a safe, environmentally friendly and very cost effective way to improve cleaning and surface preparation of metallic materials. Compared with efficient cleaning processes, it can avoid the disadvantages of ductile materials prepared by conventional technologies (cracks induced by sand-blasting for example) and treat only some selected areas (due to the optical fibers). By this way, laser technology could have several advantages and expand the range of thermal spraying. Moreover, new generations of lasers (fiber laser, disc laser) allow the development of new methods. Besides a significant bulk reduction, no maintenance, low operating cost, laser fibers can introduce alternative treatments. Combining a short-pulse laser with a scanner allows new applications in terms of surface preparation. By multiplying impacts using scanning laser, it is possible to shape the substrate surface to improve the coating adhesion as well as the mechanical behaviour.

  5. 40 CFR 761.369 - Pre-cleaning the surface.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Pre-cleaning the surface. 761.369... PROHIBITIONS Double Wash/Rinse Method for Decontaminating Non-Porous Surfaces § 761.369 Pre-cleaning the surface. If visible PCB-containing liquid is present on the surface to be cleaned, thoroughly wipe or...

  6. Laser Surface Profiler

    SciTech Connect

    Butler, M.A.; Chu, A.

    1998-11-24

    By accurately measuring the angle of reflection of a laser beam incident on a reflective surface with a position sensitive detector, changes in the surface normal direction (slope of the surface) can be determined directly. An instrument has been built that makes repeated measurements over the surface, and uses this data to produce a grayscale image of the slope. The resolution of this system to changes in the surface normal direction is found to be better than 0.01 degrees. By focusing the Iaser beam to achieve a lateral resolution of 5 pm, the resolvable surface height change due to a variation in slope is estimated to be <1 nm.

  7. Novel Applications of the Er:YAG Laser Cleaning of Old Paintings

    NASA Astrophysics Data System (ADS)

    Andreotti, A.; Bracco, P.; Colombini, M. P.; deCruz, A.; Lanterna, G.; Nakahara, K.; Penaglia, F.

    This chapter focuses on the use of Er:YAG laser cleaning technique for the removal of unwanted and/or degraded materials both from a large series of reference standards (overpainting, varnishes, patinas, and restoration materials) which simulate the layering of old paintings, and also examples from old paintings. A series of diagnostic controls (optical microscopy, SEM, FT-IR, GC-MS, and topographic techniques) were designed to study the effects of the laser radiation on the surface components, including morphological, optical, and chemical examination. The most significant results show that an effective thin-layer-removal of about 90% is obtained by submitting the painted surfaces to the laser exposure, while the rest of cleaning is rapidly accomplished in safety by applying mild solvents or aqueous methods. Consequently, possible interference with the original substrate can be noticeably minimized. No degradation compound induced by laser energy was formed. The laser cleaning procedure applied on an oil painting canvas "Morte di Adone" (seventeenth century), and on a panel tempera painting "San Nicola e San Giusto" of Domenico di Michelino (fifteenth century) shows that the surfaces cleaned by this system exhibit a morphology quite similar to that obtained by traditional cleaning methods.

  8. Critical Surface Cleaning and Verification Alternatives

    NASA Technical Reports Server (NTRS)

    Melton, Donald M.; McCool, A. (Technical Monitor)

    2000-01-01

    As a result of federal and state requirements, historical critical cleaning and verification solvents such as Freon 113, Freon TMC, and Trichloroethylene (TCE) are either highly regulated or no longer 0 C available. Interim replacements such as HCFC 225 have been qualified, however toxicity and future phase-out regulations necessitate long term solutions. The scope of this project was to qualify a safe and environmentally compliant LOX surface verification alternative to Freon 113, TCE and HCFC 225. The main effort was focused on initiating the evaluation and qualification of HCFC 225G as an alternate LOX verification solvent. The project was scoped in FY 99/00 to perform LOX compatibility, cleaning efficiency and qualification on flight hardware.

  9. The so-called dry laser cleaning governed by humidity at the nanometer scale

    NASA Astrophysics Data System (ADS)

    Grojo, D.; Delaporte, Ph.; Sentis, M.; Pakarinen, O. H.; Foster, A. S.

    2008-01-01

    Illumination with single nanosecond pulses leads to the detachment of silica particles with 250nm radii from silicon surfaces. We identify two laser-energy dependent cleaning regimes by time-of-flight particle-scattering diagnostics. For the higher energies, the ejection of particles is produced by nanoscale ablation due to the laser field enhancement at the particle-surface interface. The damage-free regime at lower energy is shown to be governed by the residual water molecules, which are inevitably trapped on the materials. We discuss the great importance that the humidity plays on the cleaning force and on the adhesion in the experiments.

  10. Cleaning Of Black Crust From Marble Substrate By Short Free Running μs Nd: YAG Laser

    NASA Astrophysics Data System (ADS)

    Khedr, A.; Pouli, P.; Fotakis, C.; Harith, M. A.

    2009-09-01

    One of the most important aspects in laser cleaning of artworks is the possibility for on-line monitoring the cleaning process. This ensures that the cleaning intervention is satisfactory without any damage to the underlying original surface. In this work it is shown that following and observing the integrated densities of the plumes generated during laser cleaning may be a simple, safe and straightforward methodology to monitor the removal process. A series of experiments on reference marble with simulated thick encrustation were considered to evaluate the plume monitoring technique. Parameters influencing the cleaning process and ablation threshold of the black crust (such as laser fluence, number of pulses etc.) were considered while the results were also evaluated under the microscope. The results of this study will be presented and discussed with the aim to establish accurate and reliable monitoring tools to follow the laser cleaning process.

  11. Cleaning Of Black Crust From Marble Substrate By Short Free Running {mu}s Nd: YAG Laser

    SciTech Connect

    Khedr, A.; Harith, M. A.; Pouli, P.; Fotakis, C.

    2009-09-27

    One of the most important aspects in laser cleaning of artworks is the possibility for on-line monitoring the cleaning process. This ensures that the cleaning intervention is satisfactory without any damage to the underlying original surface. In this work it is shown that following and observing the integrated densities of the plumes generated during laser cleaning may be a simple, safe and straightforward methodology to monitor the removal process. A series of experiments on reference marble with simulated thick encrustation were considered to evaluate the plume monitoring technique. Parameters influencing the cleaning process and ablation threshold of the black crust (such as laser fluence, number of pulses etc.) were considered while the results were also evaluated under the microscope. The results of this study will be presented and discussed with the aim to establish accurate and reliable monitoring tools to follow the laser cleaning process.

  12. Laser-induced desorption from sapphire surfaces

    SciTech Connect

    Hamza, A.V.; Schildbach, M.A.

    1992-03-01

    Laser-induced desorption of energetic ({approximately}7eV) aluminum ions was observed from clean and water-covered sapphire (1102) surfaces using time-of-flight mass spectrometry with laser wavelengths of 1064, 355, and 266 nm. In sharp contrast, O{sup +} (H{sup +} and OH{sup +}) ions were observed in electron-induced desorption measurements with 300 eV electrons from the bare (water- covered) (1102) surface. Sapphire surfaces were characterized with low energy electron diffraction, reflection electron energy loss spectroscopy, and Auger electron spectroscopy. 8 refs.

  13. Laser textured surface gradients

    NASA Astrophysics Data System (ADS)

    Ta, Van Duong; Dunn, Andrew; Wasley, Thomas J.; Li, Ji; Kay, Robert W.; Stringer, Jonathan; Smith, Patrick J.; Esenturk, Emre; Connaughton, Colm; Shephard, Jonathan D.

    2016-05-01

    This work demonstrates a novel technique for fabricating surfaces with roughness and wettability gradients and their subsequent applications for chemical sensors. Surface roughness gradients on brass sheets are obtained directly by nanosecond laser texturing. When these structured surfaces are exposed to air, their wettability decreases with time (up to 20 days) achieving both spatial and temporal wettability gradients. The surfaces are responsive to organic solvents. Contact angles of a series of dilute isopropanol solutions decay exponentially with concentration. In particular, a fall of 132° in contact angle is observed on a surface gradient, one order of magnitude higher than the 14° observed for the unprocessed surface, when the isopropanol concentration increased from 0 to 15.6 wt%. As the wettability changes gradually over the surface, contact angle also changes correspondingly. This effect offers multi-sensitivity at different zones on the surface and is useful for accurate measurement of chemical concentration.

  14. Enhancement of airborne shock wave by laser-induced breakdown of liquid column in laser shock cleaning

    SciTech Connect

    Jang, Deoksuk; Kim, Dongsik; Park, Jin-Goo

    2011-04-01

    In laser shock cleaning (LSC), the shock wave is generated by laser-induced breakdown of the ambient gas. The shock wave intensity has thus been a factor limiting the performance of the LSC process. In this work, a novel method of amplifying a laser-induced plasma-generated shock wave by the breakdown of a liquid column is proposed and analyzed. When the laser beam is focused on a microscale liquid column, a shock wave having a significantly amplified intensity compared to that generated by air breakdown alone can be generated in air. Therefore, substantially amplified cleaning force can be obtained. The dynamics of a shock wave induced by a Q-switched Nd:YAG laser was analyzed by laser flash shadowgraphy. The peak pressure of the laser-induced shock wave was approximately two times greater than that of air breakdown at the same laser fluence. The proposed method of shock wave generation is expected to be useful in various applications of laser shock processing, including surface cleaning.

  15. Surface magnetic enhancement for coal cleaning

    SciTech Connect

    Hwang, J.Y.

    1992-01-01

    The program consisted of a fundamental study to define the chemistry for the interactions between magnetic reagent and mineral and coal particles, a laboratory study to determine the applicability of this technology on coal cleaning, and a parameter study to evaluate the technical and economical feasibility of this technology for desulfurization and de-ashing under various processing schemes. Surface magnetic enhancement using magnetic reagent is a new technology developed at the Institute. This technology can be applied to separate pyrite and other minerals particles from coal with a magnetic separation after adsorbing magnetic reagent on the surface of pyrite and other minerals particles. Particles which have absorbed magnetic reagent are rendered magnetic. The adsorption can be controlled to yield selectivity. Thus, the separation of traditionally nonmagnetic materials with a magnetic separator can be achieved. Experiments have been performed to demonstrate the theoretical fundamentals and the applications of the technology. Adsorbability, adsorption mechanisms, and adsorption selectivity are included in the fundamental study. The effects of particle size, magnetic reagent dosage, solid contents, magnetic matrix, applied magnetic field strengths, retention times, and feed loading capacities are included in the application studies. Three coals, including Illinois No. 6, Lower Kittanning and Pocahontas seams, have been investigated. More than 90% pyritic sulfur and ash reductions have been achieved. Technical and economic feasibilities of this technology have been demonstrated in this study. Both are competitive to that of the froth flotation approach for coal cleaning.

  16. Directional self-cleaning superoleophobic surface.

    PubMed

    Zhao, Hong; Law, Kock-Yee

    2012-08-14

    In this work, we report the creation of a grooved surface comprising 3 μm grooves (height ~4 μm) separated by 3 μm from each other on a silicon wafer by photolithography. The grooved surface was then modified chemically with a fluorosilane layer (FOTS). The surface property was studied by both static and dynamic contact angle measurements using water, hexadecane, and a polyethylene wax ink as the probing liquids. Results show that the grooved surface is both superhydrophobic and superoleophobic. Its observed contact angles agree well with the calculated Cassie-Baxter angles. More importantly, we are able to make a replica of the composite wax ink-air interface and study it by SEM. Microscopy results not only show that the droplet of the wax ink "sits" on air in the composite interface but also further reveal that the ink drop actually pins underneath the re-entrant structure in the side wall of the grooved structure. Contact angle measurement results indicate that wetting on the grooved surface is anisotropic. Although liquid drops are found to have lower static and advancing contact angles in the parallel direction, the drops are found to be more mobile, showing smaller hysteresis and lower sliding angles (as compared to the FOTS wafer surface and a comparable 3-μm-diameter pillar array FOTS surface). The enhanced mobility is attributable to the lowering of the resistance against an advancing liquid because 50% of the advancing area is made of a solid strip where the liquid likes to wet. This also implies that the contact line for advancing is no longer smooth but rather is ragged, having the solid strip area leading the wetting and the air strip area trailing behind. This interpretation is supported by imaging the geometry of the contact lines using molten ink drops recovered from the sliding angle experiments in both the parallel and orthogonal directions. Because the grooved surface is mechanically stronger against mechanical abrasion, the self-cleaning

  17. Experimental and theoretical analysis of the laser shock cleaning process for nanoscale particle removal

    NASA Astrophysics Data System (ADS)

    Kim, Dongsik; Oh, Bukuk; Jang, Deoksuk; Lee, Jeong-Wook; Lee, Jong-Myoung

    2007-07-01

    The laser shock cleaning (LSC) process has been shown to be effective for removing submicron-sized contaminant particles from solid surfaces and thus bears strong potential in various applications. In this work, experimental and theoretical analysis are conducted to reveal the underlying physical mechanisms of the LSC process, with emphasis on the laser-induced hydrodynamics and the effect of external gas-jet injection through a nozzle. A two-dimensional theoretical model is proposed for rigorous simulation of the hydrodynamic phenomena occurring in the LSC process. The hydrodynamics computed by the model is in qualitative agreement with experimental observations and reveal the details of the physics involved in the cleaning process. The effect of gas blowing on the cleaning performance is analyzed both experimentally and theoretically. The results indicate that the gas flow can significantly change the hydrodynamics and increase the cleaning efficiency by reducing the chance of particle redeposition.

  18. Clean, cold, and liquid-free laser transfer of biomaterials

    NASA Astrophysics Data System (ADS)

    Kononenko, T. V.; Nagovitsyn, I. A.; Chudinova, G. K.; Mihailescu, I. N.

    2011-04-01

    Blister-based laser induced forward transfer (BB-LIFT) is proposed as a promising tool for clean, cold and liquid-free local transfer of various organic substances. The feature of the given technique is that ejection of the material from the target results from non-destructive blistering of a thin metal film covering a transparent support. Applicability of the BB-LIFT driven by nanosecond laser pulses for micro-patterning of few organic Langmuir films was examined. Clean laser transfer with negligible material heating has been demonstrated for the nanoaggregated porphyrin films under optimized processing conditions. However, laser transfer of biopolymers, which form elastic and durable films at the target, meets essential problems and requires new solutions.

  19. Critical Surface Cleaning and Verification Alternatives

    NASA Technical Reports Server (NTRS)

    Melton, Donald M.; McCool, A. (Technical Monitor)

    2000-01-01

    A viewgraph presentation outlines the goal, scope, and background of the cleaning solvent HCFC 225G. HCFC 225G is compared to other cleaning solvents such as Freon 113 and HFE 7100. Test results of hardware submersion in HCFC 225G and Freon 113 are shown. Project accomplishments, average cleaning efficiency, and hardware qualification are discussed. Results show HCFC 225G is an excellent cleaning and verification solvent for industrial contaminants.

  20. Influence of diamond turning and surface cleaning processes on the degradation of KDP crystal surfaces

    NASA Astrophysics Data System (ADS)

    Kozlowski, Mark R.; Thomas, Ian M.; Edwards, Gary J.; Stanion, Kenneth A.; Fuchs, Baruch A.; Latanich, L.

    1991-12-01

    One factor influencing the efficiency of KDP frequency conversion arrays on the Nova laser system at LLNL has been environmental degradation, or `fogging,' of the crystal surfaces. Decreases in array transmission by as much as 20% have been attributed to crystal fogging. The surfaces of the 27 cm square Nova array crystals are prepared by a wet diamond-turning process. The rate of surface fogging has been associated with several parameters of the diamond turning and subsequent cleaning processes. High humidity during diamond turning, storage, and use on the laser tends to accelerate the fogging. We suspect that some of the additives present in the diamond turning oil increase the fogging rate and have found a machining oil which minimizes this surface degradation. Efficient removal of the machining oils from the crystal surface also minimizes the fogging problem. Care must be taken to use cleaning solvents which do not cause additional surface degradation. The fogging rate is sensitive to the crystallographic orientation of the material as well as to surface roughness related to the diamond turning process. Accelerated fogging at diamond turning artifacts may increase crystal surface roughness causing increased beam modulation and scattering losses.

  1. Influence of diamond turning and surface cleaning processes on the degradation of KDP crystal surfaces

    SciTech Connect

    Kozlowski, M.R.; Thomas, I.; Edwards, G.; Stanion, K.; Fuchs, B.

    1991-06-24

    One factor influencing the efficiency of KDP (potassium dihydrogen phosphate) frequency conversion arrays on the Nova laser system at LLNL has been environmental degradation, or fogging'', of the crystal surfaces. Decreases in array transmission by as much as 20% have been attributed to crystal fogging. The surfaces of the 27-cm square Nova array crystals are prepared by a wet diamond-turning process. The rate of surface fogging has been associated with several parameters of the diamond turning and subsequent cleaning processes. High humidity during diamond turning, storage, and use on the laser tends to accelerate the fogging. We suspect that some of the additives present in the diamond turning oil increase the fogging rate and have found a machining oil which minimizes this surface degradation. Efficient removal of the machining oils from the crystal surface also minimizes the fogging problem. Care must be taken to use cleaning solvents which do not cause additional surface degradation. The fogging rate is sensitive to the crystallographic orientation of the material as well as to surface roughness related to the diamond turning process. Accelerated fogging at diamond turning artifacts may increase crystal surface roughness causing increased beam modulation and scattering losses. 5 refs. 5 figs.

  2. Crude oil remote sensing, characterization, and cleaning with continuous wave and pulsed lasers

    NASA Astrophysics Data System (ADS)

    Kukhtarev, N.; Kukhtareva, T.; Gallegos, S. C.; Chirita, A.

    2014-10-01

    We demonstrate a successful combination of several optical methods of remote sensing (coherent fringe projection illumination (CFP), holographic in-line interferometry (HILI), laser induced fluorescence,) for detection, identification, and characterization of crude oil. These methods enable the three-dimensional characterization of oil spills that is important for practical applications. Combined methods of CFP and HILI are described in the frame of coherent superposition of partial interference patterns. We show that in addition to detection/identification of oil, laser illumination in the green-blue region can also degrade oil slicks. We tested these methods on differentsurfaces contaminated by oil , which include: oil on water, oil on flat solid surfaces, and oil on curved surfaces of. We use coherent fiber bundles for the detection and monitoring of the laser-induced oil degradation in pipes.. Both continuouswave (CW) and pulsed lasers are tested using pump-probe schemes. This finding allows us to suggest that properly structured laser clean-up can be an alternative environmental-friendly method of decontamination and cleaning, which can be an alternative to chemical methods, which are dangerous to environmentApplication of holographic amplifier with phase conjugation will allow to increase sensitivity, reduce aberrations from atmospheric distortions and to focus back-reflected amplified beam on the contaminated area thus accelerating laser cleaning.

  3. A New Solution for the Painting Artwork Rear Cleaning and Restoration: The Laser Cleaning

    NASA Astrophysics Data System (ADS)

    Andriani, S. E.; Catalano, I. M.; Brunetto, A.; Daurelio, G.; Vona, F.

    Before restoring a painting, in order to assure a good level of adhesion between the canvas and the preparation layer or to reline the painting, it is often necessary to consolidate the canvas by intervening on the painting rear. Traditional cleaning techniques, chemical combined with mechanical ones, show an important drawback: The cleaning process and technique enfeeble permanently the canvas. The present work performs a comparative study for evaluating both the cleaning process efficiency and the canvas integrity preservation by using various cleaning methods, including Nd:YAG laser systems and traditional techniques. The effects of a short free running mode (λ = 1,064 nm, pulse duration of 40-110 μs), a long Q-switched mode (λ = 1, 064 nm, pulse duration of 200 ns) and a Q-switched mode (λ = 1,064 and 532 nm, pulse duration of 6 ns) of Nd:YAG laser irradiation on the hemp canvas of a seventeenth century painting are investigated. The analyses using FTIR spectroscopy and degradation mapping by optical microscope, with photographs taken before, during and after the cleaning process, were carried out. The work is still in progress.

  4. Influence of surface cleaning on dewetting of thin polystyrene films

    NASA Astrophysics Data System (ADS)

    Müller-Buschbaum, P.

    2003-11-01

    Thin polystyrene (PS) films on top of silicon substrates are a frequently investigated model system in the framework of unstable films. However, with respect to stability the various experiments yielded contradictory results. Focussing on the influence of preparation conditions such as the surface cleaning solves these contradictions. By applying different surface cleans the PS film can be changed from a stable homogeneous one into a completely dewetted one. In addition to the type of clean applied, the time between cleaning the surface and spin-coating the polymeric layer on top turned out to be an important experimental parameter.

  5. Effectiveness of duct cleaning methods on newly installed duct surfaces.

    PubMed

    Holopainen, R; Asikainen, V; Tuomainen, M; Björkroth, M; Pasanen, P; Seppänen, O

    2003-09-01

    Two kinds of air duct cleaning methods, mechanical brushing with different brushes and compressed air cleaning, were compared in the laboratory and in newly built buildings. The ducts were contaminated either with test dust or with dust originated from a construction site. The amount of dust on the duct surface was measured with the vacuum test method and estimated visually before and after the cleaning. In addition, the cleaning times of the different techniques were compared and the amount of residual oil in the ducts was measured in the laboratory test. The brushing methods were more efficient in metal ducts, and compressed air cleaning was more efficient in plastic ducts. After the duct cleaning the mean amount of residual dust on the surface of the ducts was cleaning in the field. The decrease in the dust deposits on the surface ranged from 86 to 99% and from 75 to 94% in the ducts cleaned in the laboratory or in the building site, respectively. The oil residues and the dust stuck onto the oil were difficult to scrape off and remove, and none of the cleaning methods were capable of cleaning the oily duct surfaces efficiently enough. Thus new installations should consist only of oil-free ducts.

  6. Environmentally Clean Mitigation of Undesirable Plant Life Using Lasers

    SciTech Connect

    Rubenchik, A M; McGrann, T J; Yamamoto, R M; Parker, J M

    2009-07-01

    This concept comprises a method for environmentally clean destruction of undesirable plant life using visible or infrared radiation. We believe that during the blossom stage, plant life is very sensitive to electromagnetic radiation, with an enhanced sensitivity to specific spectral ranges. Small doses of irradiation can arrest further plant growth, cause flower destruction or promote plant death. Surrounding plants, which are not in the blossoming stage, should not be affected. Our proposed mechanism to initiate this effect is radiation produced by a laser. Tender parts of the blossom possess enhanced absorptivity in some spectral ranges. This absorption can increase the local tissue temperature by several degrees, which is sufficient to induce bio-tissue damage. In some instances, the radiation may actually stimulate plant growth, as an alternative for use in increased crop production. This would be dependent on factors such as plant type, the wavelength of the laser radiation being used and the amount of the radiation dose. Practical, economically viable realization of this concept is possible today with the advent of high efficiency, compact and powerful laser diodes. The laser diodes provide an efficient, environmentally clean source of radiation at a variety of power levels and radiation wavelengths. Figure 1 shows the overall concept, with the laser diodes mounted on a movable platform, traversing and directing the laser radiation over a field of opium poppies.

  7. Investigation of aluminum surface cleaning using cavitating fluid flow

    NASA Astrophysics Data System (ADS)

    Ralys, Aurimas; Striška, Vytautas; Mokšin, Vadim

    2013-12-01

    This paper investigates efficiency of specially designed atomizer used to spray water and cavitate microbubbles in water flow. Surface cleaning system was used to clean machined (grinded) aluminum surface from abrasive particles. It is established that cleaning efficiency depends on diameter of the diffuser, water pressure and distance between nozzle and metal surface. It is obtained that the best cleaning efficiency (100%) is achieved at pressure 36 bar, when diameter of diffuser is 0.4 mm and distance between nozzle and surface is 1 mm. It is also established that satisfactory cleaning efficiency (80%) is achieved not only when atomizer is placed closer to metal surface, but also at larger (120 mm) distances.

  8. Experimental study on the effect of wavelength and fluence in the laser cleaning of silvering in late Roman coins (Mid 3rd/4th century AD)

    NASA Astrophysics Data System (ADS)

    Vlachou-Mogire, C.; Drakaki, E.; Serafetinides, A. A.; Zergioti, I.; Boukos, N.

    2007-03-01

    The political problems in Late Roman Empire caused significant changes in the coin technology. The silver content dropped severely and a new technology, in all the mints operating around the Empire, was introduced. For the production of these coins, copper based quaternary alloys were used and their surface was covered by a silver amalgam plating layer. Hoards of these coins have been recovered in thousands from across the Empire, however, their treatment has been problematic. Both mechanical and chemical cleaning results in the damage or the complete destruction of the thin silver layer. The use of laser technology in the cleaning of works of art has a wide range of applications which includes metallic objects. The main aim of this work was to investigate the use of lasers in the cleaning of the thin silver plating layers found in late Roman coins. The optimisation of laser parameters was achieved through comparative cleaning tests by employing Nd:YAG (532 nm and 266 nm) laser systems. The cleaning results on the plated areas were characterised by optical microscopy, and SEM-EDX analysis. Following a systematic investigation and many cleaning trials on two different wavelengths and fluence values, optimum irradiation parameters were thoroughly demonstrated. Microscopic observations of the cleaned areas evidenced complete removal of the encrustation and high selectivity of the laser cleaning. Neither thermal or mechanical injuries, nor cuprite blackening were observed on the cleaned surfaces at the optimum laser cleaning technique, using 532 nm of the Nd: YAG laser.

  9. Laser Cleaning of Peristyle in Diocletian Palace in Split (HR)

    NASA Astrophysics Data System (ADS)

    Almesberger, D.; Rizzo, A.; Zanini, A.; Geometrante, R.

    Before starting the cleaning program of the peristyle of Diocletian Palace in Split, a series of tests have been performed on it. First of all, the state of conservation of columns and capitals has been assessed applying non-destructive techniques such as thermography, magnetoscopy and superficial ultrasonic tests. All the areas with black crusts, exfoliation and stone cracks have been determined. In this stage, parameters such as water absorption and colour have been estimated in order to compare them with those measured after the cleaning operation. Then, more than 3-month period of tests have been performed to set up all the parameters concerning the application of the laser cleaning techniques. In this chapter, the results of these preliminary investigations are presented.

  10. Cleanliness audit of clinical surfaces and equipment: who cleans what?

    PubMed

    Anderson, R E; Young, V; Stewart, M; Robertson, C; Dancer, S J

    2011-07-01

    Current guidelines recommend regular cleaning of clinical equipment. We monitored items on a surgical ward for predominant user, hand-touch frequency, cleaning responsibilities and measurement of organic soil. Equipment was assessed in triplicate against a cleanliness benchmark of 100 relative light units (RLU) using the Hygiena® ATP system. There were 44 items, of which 21 were cleaned by clinical support workers (CSWs), five by domestic staff; three by nurses, three by doctors, and 12 with no designated cleaning responsibility. Geometric mean RLUs ranged from 60 to 550/100 cm² for small items such as hand-gel containers, bed control, blood pressure cuff and clinical notes; with similar values of 80-540/100 cm² RLU for larger items such as electrocardiogram machine, defibrillator, trolleys and tables. Overall geometric mean was 249/100 cm² RLU for all surfaces, with 84% (37 of 44) items exceeding the 100RLU benchmark. Of 27 items cleaned by clinical staff, 24 (89%) failed the benchmark. Of 12 sites with no cleaning specification, 11 (92%) failed the benchmark. Three of seven 'clean' sites (<100/100 cm² RLU) were cleaned by domestic staff. Average log(10) RLU of surfaces cleaned by domestics were 64% lower compared with surfaces cleaned by CSWs (95% confidence interval: 35%, 80%; P=0.019). In conclusion, clinical equipment frequently demonstrates high levels of organic soil, whether or not items have assigned cleaning responsibility. These findings suggest that cleaning practices for clinical equipment may require review, along with education of staff with specific cleaning responsibilities.

  11. Evaluation of laser cleaning for the restoration of tarnished silver artifacts

    NASA Astrophysics Data System (ADS)

    Palomar, T.; Oujja, M.; Llorente, I.; Ramírez Barat, B.; Cañamares, M. V.; Cano, E.; Castillejo, M.

    2016-11-01

    In this study we evaluate the laser cleaning of tarnished pure and sterling silver substrates using a nanosecond Q-switched Nd:YAG laser at 1064, 532 and 266 nm. To assess the effects associated with cyclic laser cleaning treatments, several cycles of tarnishing followed by laser cleaning were applied on silver coupons that were characterized by gravimetry, colorimetry, scanning electron microscopy, X-ray photoelectron spectroscopy and micro-Raman spectroscopy. According to the obtained results, none of the three wavelengths is recommended for laser cleaning of pure silver objects, while for sterling silver artifacts, the visible laser wavelength of 532 nm seems the most appropriate.

  12. Laser heterodyne surface profiler

    DOEpatents

    Sommargren, Gary E.

    1984-01-01

    Method and apparatus for testing the deviation of the face of an object from a flat smooth surface using a laser beam having two plane-polarized components, one of a frequency greater than the other to produce a difference frequency with a phase to be used as a reference. The beam also is split into its two components which are directed onto spaced apart points on the face of the object. The object is rotated on an axis coincident with one component as a reference. The other component follows a circular track on the face of the object as the object is rotated. The two components are recombined after reflection to produce a difference frequency having a phase that is shifted in an amount that is proportional to the difference in path length as compared to the reference phase to produce an electrical output signal proportional to the deviation of the height of the surface along the circular track. The output signal is generated by means of a phase detector that includes a first photodetector in the path of the recombined components and a second photodetector in the path of the reference phase. The output signal is dependent on the phase difference of the two photodetector signals. A polarizer, a quarter-wave plate and a half-wave plate are in series in the path of the reference phase. Rotation of the half-wave plate can be used for phase adjustment over a full 360.degree. range for initial calibration of the apparatus.

  13. Optimized in-situ window cleaning system by laser blow-off through optical fiber

    NASA Astrophysics Data System (ADS)

    Alfier, A.; Pasqualotto, R.; Giudicotti, L.; Cervaro, V.; Franchin, L.

    2010-05-01

    An optimized in-situ window cleaning system by laser blow-off through optical fiber has been developed on the basis of a feasibility study previously presented. The beam generated from a Q-switched Nd:YAG laser (up to 330mJ output energy, pulse duration 5ns FWHM with 10Hz repetition rate) is launched into a high damage threshold optical fiber (Ø=1mm) through an f=80mm lens kept in a sealed box at 1mbar pressure. The fiber output is focused on the coated surface of a vacuum window previously exposed to the plasma of the RFX-mod experiment. We investigate the energy density threshold necessary to ablate the impurity deposition substrate: above threshold a single laser pulse recovers ~95% of the window transmission before its exposure to the plasma, while below it the efficiency of the cleaning process is too poor. The system so conceived can clean completely the largest window on RFX-mod (104mm2 surface) in about 20minutes. We also present first results obtained firing the laser directly on a bundle of small core diameter fibers, showing performance similar to those attainable with commercial products.

  14. Optical cell cleaning with NIR femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Uchugonova, Aisada; Breunig, Hans Georg; Batista, Ana; König, Karsten

    2015-03-01

    Femtosecond laser microscopes have been used as both micro and nanosurgery tools. The optical knock-out of undesired cells in multiplex cell clusters shall be further reported on in this study. Femtosecond laser-induced cell death is beneficial due to the reduced collateral side effects and therefore can be used to selectively destroy target cells within monolayers, as well as within 3D tissues, all the while preserving cells of interest. This is an important characteristic for the application in stem cell research and cancer treatment. Non-precise damage compromises the viability of neighboring cells by inducing side effects such as stress to the cells surrounding the target due to the changes in the microenvironment, resulting from both the laser and laser-exposed cells. In this study, optimum laser parameters for optical cleaning by isolating single cells and cell colonies are exploited through the use of automated software control. Physiological equilibrium and cellular responses to the laser induced damages are also investigated. Cell death dependence on laser focus, determination and selectivity of intensity/dosage, controllable damage and cell recovery mechanisms are discussed.

  15. Laser Cleaning of Polyurethane Foam: An Investigation using Three Variants of Commercial PU Products

    NASA Astrophysics Data System (ADS)

    Dinesen, U. Staal; Westergaard, M.

    In this study, tests were undertaken to ascertain whether the laser could achieve a better level of cleaning on polyurethane foam than vacuum cleaning. Optimum laser parameters were found using statistics on data from color measurements. The laser proved to be very effective regarding the removal of dust, but also caused damage on some PU-variants. The laser cleaning has been carried out at National Workshops for Arts and Crafts, Copenhagen, Denmark.

  16. Surface magnetic enhancement for coal cleaning

    SciTech Connect

    Hwang, J.Y.

    1989-01-01

    The fundamental chemistry for selective adsorption of magnetizing reagent on coal-associated minerals to enhance the magnetic susceptibility of minerals have been established in Phase I study. The application of the results on coal cleaning is in progress in the Phase II study. The task in Phase II study for coal selection, preparation, and characterization is completed in this reporting period. The optimization of adsorption conditions for {minus}48 mesh ROM coals and flotation concentrates is about completed. Experiments have shown that successful coal cleaning can be obtained with this magnetizing reagent approach. The task to adapt the approach to various processing schemes is just initiated.

  17. EUV mask surface cleaning effects on lithography process performance

    SciTech Connect

    George, Simi; Baclea-an, Lorie Mae; Naulleau, Patrick; Chen, Robert J.; Liang, Ted

    2010-06-18

    The reflective, multilayer based, mask architectures for extreme ultraviolet (EUV) lithography are highly susceptible to surface oxidation and contamination. As a result, EUV masks are expected to undergo cleaning processes in order to maintain the lifetimes necessary for high volume manufacturing. For this study, the impact of repetitive cleaning of EUV masks on imaging performance was evaluated. Two, high quality industry standard, EUV masks are used for this study with one of the masks undergoing repeated cleaning and the other one kept as a reference. Lithographic performance, in terms of process window analysis and line edge roughness, was monitored after every two cleans and compared to the reference mask performance. After 8x clean, minimal degradation is observed. The cleaning cycles will be continued until significant loss imaging fidelity is found.

  18. Laser heterodyne surface profiler

    DOEpatents

    Sommargren, G.E.

    1984-06-26

    Method and apparatus are disclosed for testing the deviation of the face of an object from a flat smooth surface using a laser beam having two plane-polarized components, one of a frequency greater than the other to produce a difference frequency with a phase to be used as a reference. The beam also is split into its two components which are directed onto spaced apart points on the face of the object. The object is rotated on an axis coincident with one component as a reference. The other component follows a circular track on the face of the object as the object is rotated. The two components are recombined after reflection to produce a difference frequency having a phase that is shifted in an amount that is proportional to the difference in path length as compared to the reference phase to produce an electrical output signal proportional to the deviation of the height of the surface along the circular track. The output signal is generated by means of a phase detector that includes a first photodetector in the path of the recombined components and a second photodetector in the path of the reference phase. The output signal is dependent on the phase difference of the two photodetector signals. A polarizer, a quarter-wave plate and a half-wave plate are in series in the path of the reference phase. Rotation of the half-wave plate can be used for phase adjustment over a full 360[degree] range for initial calibration of the apparatus. 12 figs.

  19. Resolution of contamination problems affecting laser surface certification inspection

    NASA Astrophysics Data System (ADS)

    Jackson, L. C.

    1982-03-01

    Contamination from particulate and organic residues which interfered, with the laser surface certification (LSC) inspection of some parts was found to come from three sources: particulate and organic residues from polishing compounds; organic films from cleaning solvents; and particles and organic residues transferred from plastic fixtures used to process these parts. The manufacturing cleaning process was not effective in removing all polishing compound residues, and an extensive cleaning procedure was developed using two solvents in a multicycle ultrasonic/vapor degreasing procedure. Parts were then subjected to gas plasma cleaning which removed the organic films left by the solvent cleaning. Plastic and rubber materials were evaluated for their contamination transfer characteristics; a fluorocarbon elastomer was the least contaminating. Inspection data established the efficacy of the cleaning procedure. After design relaxation, a single stage ultrasonic vapor degreasing process was used to achieve product acceptance.

  20. Monitoring laser cleaning of titanium alloys by probe beam reflection and emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Whitehead, D. J.; Crouse, P. L.; Schmidt, M. J. J.; Li, L.; Turner, M. W.; Smith, A. J. E.

    2008-10-01

    Studies have shown excimer laser cleaning to be an effective non-chemical alternative method for removing contaminants from surfaces of titanium alloys in preparation for electron beam welding and diffusion bonding, with reference to aerospace applications. Among several important criteria for process acceptability, is the absence of oxide formation. This paper investigates the viability of using a probe beam reflection (PBR) system and laser plume emission spectroscopy (PES) for detection of incipient oxide formation on three typical aerospace titanium alloys, viz. Ti64, Ti6246, and IMI834. These diagnostic techniques have been shown to be capable of sensing different components in the emission plume and yield quantitative results. Results from this work correlate closely with previously reported cleaning mechanisms. The oxidation threshold, as well as the operating window for successful decontamination, is discussed.

  1. A study of surface optical properties for characterizing the cleaning process of paintings

    NASA Astrophysics Data System (ADS)

    Fontana, R.; Barucci, M.; Pampaloni, E.; Pezzati, L.; Daffara, C.

    2013-05-01

    "Cleaning" is a process of carefully identifying the cause of any deterioration or discolouration and then removing or treating these layers. The skill of the restorer is not only to understand the techniques and media used by the artist, but also to recognize what beauty lies beneath the veils of many years of neglect or adverse conditions. Surface cleaning is then one of the most important and sometimes controversial stages of the conservation process: it is an irreversible process that generally results in substantial physical changes of the object surface, raising thus a series of questions regarding aesthetics, the potential loss of historical information, and the ability to control the cleaning process adequately. Decisions have to be made regarding partial or complete removal of varnish: technical considerations include selection of a method that allows a great deal of control in the cleaning process, so that undesired layers can be removed without damaging the underlying ones by means of traditional cleaning methods, including mechanical or chemical removal. In this work we present a study of the optical properties of painting surfaces for the characterization of the cleaning process. Analyses were carried out by means of laser micro-profilometry and confocal microscopy. Measurements were carried out on a few paintings which are under repair at the Opificio delle Pietre Dure in Florence. Selected areas were surveyed with the two above mentioned techniques and results were correlated.

  2. Spread of bacteria on surfaces when cleaning with microfibre cloths.

    PubMed

    Bergen, L K; Meyer, M; Høg, M; Rubenhagen, B; Andersen, L P

    2009-02-01

    The impact of environmental contamination on nosocomial cross-transmission is mostly unresolved and in Danish hospitals assessment of cleaning is based on visible criteria only. The use of premoistened microfibre cloths and the 16-side method have been introduced into Danish hospitals because of economic and ergonomic advantages but they have not been evaluated for applicability in hospital cleaning. Our hypothesis was that this method may spread bacteria. A surface was contaminated with bacteria (4 cfu/bacteria/cm(2)), and cleaned with a premoistened microfibre cloth folded to 16-side use. Each of 15 sterile surfaces was cleaned with a new side of the microfibre cloth; imprints were made and the experiment repeated 12 times. After cleaning, the contaminated surface imprints of microfibre cloths showed a median of 45.5 cfu/plate for E. faecalis and 2.5 cfu/plate for B. cereus. Median values from imprints from cloth sides 2-16 were between 1 and 12 cfu/plate for E. faecalis and 0 cfu/plate for B. cereus. Imprints of the contaminated surfaces were a median of 45.5 cfu/plate for E. faecalis, giving a reduction of 5.6-fold. For B. cereus the median value was 0 cfu/plate. The surface numbers 2-16 had median values between 0.5 and 7.5 for E. faecalis, which was spread to 11-15 of the 15 sterile surfaces (P<0.01). B. cereus was found in six out of 180 imprints on surfaces 2-16, all with 1 cfu/plate (non-significant). The implication is that although there was an overall reduction in bacterial counts on the contaminated surface, bacteria were spread to subsequently cleaned surfaces.

  3. Characterization of Thermal Sprayed Aluminum and Stainless Steel Coatings for Clean Laser Enclosures

    SciTech Connect

    Chow, R; Decker, T A; Gansert, R V; Gansert, D

    2000-04-06

    Surfaces of steel structures that enclose high-fluence, large-beam lasers have conventional and unconventional requirements. Aside from rust prevention, the surfaces must resist laser-induced degradation and the contamination of the optical components. The latter requires a surface that can be precision cleaned to low levels of particulate and organic residue. In addition, the surface treatment for the walls should be economical to apply because of the large surface areas involved, and accommodating with intricate joint geometries. Thermal sprayed coatings of aluminum (Al) and stainless steel are candidate surface materials. Coatings are produced and characterized for porosity, smoothness, and hardness. These properties have a bearing on the cleanliness of the coating. The laser resistance of Al and 3 16L coatings are given. The paper summarizes the characterization of twin-wire-arc deposited Al, high-velocity-oxygen-fueled (HVOF) deposited Al, flame-sprayed 316L, and HVOF deposited316L. The most promising candidate coating is that of HVOF Al. This Al coating has the lowest porosity (8%) compared the other three coatings and relatively low hardness (100 VHN). The as-deposited roughness (Ra) is 433 pinches, but after a quick sanding by hand, the roughness decreased to 166 pinches. Other post-coat treatments are discussed. HVOF aluminum coatings are demonstrated. Al coatings are corrosion barriers for steel, and this work shows promising resistance to laser damage and low particulation rates.

  4. Nonhazardous solvent composition and method for cleaning metal surfaces

    DOEpatents

    Googin, John M.; Simandl, Ronald F.; Thompson, Lisa M.

    1993-01-01

    A solvent composition for displacing greasy and oily contaminants as well as water and/or aqueous residue from metallic surfaces, especially surfaces of radioactive materials so that such surfaces can be wiped clean of the displaced contaminants, water and/or aqueous residue. The solvent composition consists essentially of a blend of nonpolar aliphatic hydrocarbon solvent having a minimum flash point of about 140.degree. F. and 2 to 25 volume percent of a polar solvent having a flash point sufficiently high so as to provide the solvent composition with a minimum flash point of at least 140.degree. F. The solvent composition is nonhazardous so that when it is used to clean the surfaces of radioactive materials the waste in the form of paper or cloth wipes, lab coats and the like used in the cleaning operation is not considered to be mixed waste composed of a hazardous solvent and a radioactive material.

  5. Nonhazardous solvent composition and method for cleaning metal surfaces

    DOEpatents

    Googin, J.M.; Simandl, R.F.; Thompson, L.M.

    1993-05-04

    A solvent composition for displacing greasy and oily contaminants as well as water and/or aqueous residue from metallic surfaces, especially surfaces of radioactive materials so that such surfaces can be wiped clean of the displaced contaminants, water and/or aqueous residue. The solvent composition consists essentially of a blend of nonpolar aliphatic hydrocarbon solvent having a minimum flash point of about 140 F and 2 to 25 volume percent of a polar solvent having a flash point sufficiently high so as to provide the solvent composition with a minimum flash point of at least 140 F. The solvent composition is nonhazardous so that when it is used to clean the surfaces of radioactive materials the waste in the form of paper or cloth wipes, lab coats and the like used in the cleaning operation is not considered to be mixed waste composed of a hazardous solvent and a radioactive material.

  6. Indium phosphide negative electron affinity photocathodes: Surface cleaning and activation

    NASA Astrophysics Data System (ADS)

    Sun, Yun

    InP(100) is a very important semi-conductor for many applications. When activated by Cs and oxygen, the InP surface achieves the state of Negative Electron Affinity (NEA) making the Cs+O/InP system a very efficient electron source. Despite many years of study, the chemical cleaning and activation of InP are still not well understood. In our work, we have established an understanding of the basic physics and chemistry for the chemical cleaning and activation of the InP(100) surface. Synchrotron Radiation Photoelectron Spectroscopy is the main technique used in this study because of its high surface sensitivity and ability to identify chemical species present on the surface at each stage of our process. A clean, stoichiometric InP(100) surface is crucial for obtaining high performance of NEA photocathodes. Therefore, the first part of our study focused on the chemical cleaning of InP(100). We found that hydrogen peroxide based solutions alone, originally developed to clean GaAs(100) surfaces and widely used for InP(100), do not result in clean InP(I00) surfaces because oxide is left on the surface. A second cleaning step, which uses acid solutions like HCl or H2SO4, can remove all the oxide and leave a 0.4 ML protective layer of elemental phosphorous on the surface. The elemental phosphorous can be removed by annealing at 330°C and a clean InP(100) surface can be obtained. Cs deposition on InP(100) surface shows clear charge transfer from the Cs ad-atoms to the substrate. When the Cs/InP(100) surface is dosed with oxygen, the charge transfer from the Cs to substrate is reduced and substrate is oxidized. The activation of InP as a NEA photocathode is carried out by an alternating series of steps consisting of Cs deposition and Cs+O co-deposition. Two types of oxygen are found after activation. The first is dissociated oxygen and the other is a di-oxygen species (peroxide or superoxide). The decay of quantum-yield with time and with annealing is studied and changes in

  7. Design Surfaces by Laser Remelting

    NASA Astrophysics Data System (ADS)

    Temmler, André; Willenborg, Edgar; Wissenbach, Konrad

    The surface of a part or product strongly influences its properties and functions. These are, e.g., abrasion and corrosion resistance, insensitivity to scratches, haptics as well as the visual impression to the customer. Therefore, many plastic parts have structured surfaces like leather textures on car dashboards. Usually these structures are integrated in the injection mould for the production of the plastic parts and then transferred to the plastic parts during the injection moulding process. A new approach to structuring metallic surfaces with laser radiation is structuring by remelting. Another approach of enhancing the appearance of design surfaces is creating a two-gloss effect by selective laser polishing. Both laser-based processes are based on reallocation of material instead of ablation.

  8. Laser surface modification of PEEK

    NASA Astrophysics Data System (ADS)

    Riveiro, A.; Soto, R.; Comesaña, R.; Boutinguiza, M.; del Val, J.; Quintero, F.; Lusquiños, F.; Pou, J.

    2012-09-01

    Polyether-ether-ketone (PEEK) is a synthetic thermoplastic polymer with excellent mechanical and chemical properties, which make it attractive for the field of reconstructive surgery. Nevertheless, this material has a poor interfacial biocompatibility due to its large chemical stability which induces poor adhesive bonding properties. The possibilities of enhancing the PEEK adhesive properties by laser treatments have been explored in the past. This paper presents a systematic approach to discern the role of laser irradiation wavelength on the surface modification of PEEK under three laser wavelengths (λ = 1064, 532, and 355 nm) with the aim to determine the most adequate processing conditions to increase the roughness and wettability, the main parameters affecting cell adhesion characteristics of implants. Overall results show that the ultraviolet (λ = 355 nm) laser radiation is the most suitable one to enhance surface wettability of PEEK.

  9. SnTe microcrystals: Surface cleaning of a topological crystalline insulator

    NASA Astrophysics Data System (ADS)

    Saghir, M.; Walker, M.; McConville, C. F.; Balakrishnan, G.

    2016-02-01

    Investigating nanometer and micron sized materials thought to exhibit topological surface properties that can present a challenge, as clean surfaces are a pre-requisite for band structure measurements when using nano-ARPES or laser-ARPES in ultra-high vacuum. This issue is exacerbated when dealing with nanometer or micron sized materials, which have been prepared ex-situ and so have been exposed to atmosphere. We present the findings of an XPS study where various cleaning methods have been employed to reduce the surface contamination and preserve the surface quality for surface sensitive measurements. Microcrystals of the topological crystalline insulator SnTe were grown ex-situ and transferred into ultra high vacuum (UHV) before being treated with either atomic hydrogen, argon sputtering, annealing, or a combination of treatments. The samples were also characterised using the scanning electron microscopy, both before and after treatment. It was found that atomic hydrogen cleaning with an anneal cycle (200 °C) gave the best clean surface results.

  10. Crude Oil Remote Sensing, Characterization and Cleaning with CW and Pulsed Lasers

    NASA Technical Reports Server (NTRS)

    Kukhtareva, Tatiana; Chirita, Arc; Gallegos, Sonia C.

    2014-01-01

    For detection, identification and characterization of crude oil we combine several optical methods of remote sensing of crude oil films and emulsions (coherent fringe projection illumination (CFP), holographic in-line interferometry (HILI), and laser induced fluorescence). These methods allow the three-dimensional characterization of oil spills, important for practical applications. Combined methods of CFP and HILI are described in the frame of coherent superposition of partial interference patterns. It is shown, that in addition to detection/identification laser illumination in the green-blue region can also degrade oil slicks. Different types of surfaces contaminated by oil spills are tested: oil on the water, oil on the flat solid surfaces and oil on the curved surfaces of pipes. For the detection and monitoring of the laser-induced oil degradation in pipes, coherent fiber bundles were used. Both continuous-wave (CW) and pulsed lasers are tested using pump-probe schemes. This finding suggests that properly structured laser clean-up can be an alternative environmentally-friendly method of decontamination, as compared to the currently used chemical methods that are dangerous to environment.

  11. Recycling of surface-enhanced Raman substrates by ultraviolet cleaning

    NASA Astrophysics Data System (ADS)

    Sadate, Sandra; Calzzani, Fernando; Kassu, Aschalew; Sharma, Anup; Ruffin, Paul

    2010-10-01

    Commercial substrates used for surface-enhanced Raman spectroscopy (SERS) are investigated for their reusability following cleaning with 254-nm UV light from a mercury lamp. SERS of Rhodamine 6G (Rh6G, a dye) and RDX (an explosive) is investigated. It is found that without UV irradiation, the substrate is usable only once, since it is not possible to dislodge the analyte either by prolonged immersion in distilled water or by ultrasonic cleaning. However, prolonged exposure to 254-nm UV followed by immersion in distilled water removes most of the analyte, making the substrate reusable for new SERS measurements. The technique of UV cleaning is demonstrated by recycling the same substrate several times and comparing SERS spectra taken after each cleaning cycle.

  12. Study and development of 22 kW peak power fiber coupled short pulse Nd:YAG laser for cleaning applications

    NASA Astrophysics Data System (ADS)

    Choubey, Ambar; Vishwakarma, S. C.; Vachhani, D. M.; Singh, Ravindra; Misra, Pushkar; Jain, R. K.; Arya, R.; Upadhyaya, B. N.; Oak, S. M.

    2014-11-01

    Free running short pulse Nd:YAG laser of microsecond pulse duration and high peak power has a unique capability to ablate material from the surface without heat propagation into the bulk. Applications of short pulse Nd:YAG lasers include cleaning and restoration of marble, stones, and a variety of metals for conservation. A study on the development of high peak power short pulses from Nd:YAG laser along with its cleaning and conservation applications has been performed. A pulse energy of 1.25 J with 55 μs pulse duration and a maximum peak power of 22 kW has been achieved. Laser beam has an M2 value of ~28 and a pulse-to-pulse stability of ±2.5%. A lower value of M2 means a better beam quality of the laser in multimode operation. A top hat spatial profile of the laser beam was achieved at the exit end of 200 μm core diameter optical fiber, which is desirable for uniform cleaning. This laser system has been evaluated for efficient cleaning of surface contaminations on marble, zircaloy, and inconel materials for conservation with cleaning efficiency as high as 98%. Laser's cleaning quality and efficiency have been analysed by using a microscope, a scanning electron microscope (SEM), and X-ray photon spectroscopy (XPS) measurements.

  13. Influence of artificial metallic defects size on the surface cleaning process

    NASA Astrophysics Data System (ADS)

    Capoulade, J.; Natoli, J. Y.; Palmier, S.; Rullier, J. L.; Tovena, I.

    2007-01-01

    Contamination by metallic particles has been known to reduce the laser damage threshold on high power laser optics. To simulate the presence of metallic particle on the Ligne d'Integration Laser optics, silica substrates were arti.cially polluted by square aluminum dots of 5 × 5 micron2 and 50 × 50 micron2, respectively. The metallic dot sites were irradiated by a Nd:YAG laser at 1064 nm with different fluences. The sites were analyzed by Nomarski microscopy, optic profilometry and photothermal microscopy. For both sizes of metallic dots, vaporization of metal can be observed. We study in this paper the dot size influence on the surface cleaning process and the effect of the pre-irradiation mode (1 shoot or several shots).

  14. Biomimetic self-cleaning surfaces: synthesis, mechanism and applications.

    PubMed

    Xu, Quan; Zhang, Wenwen; Dong, Chenbo; Sreeprasad, Theruvakkattil Sreenivasan; Xia, Zhenhai

    2016-09-01

    With millions of years of natural evolution, organisms have achieved sophisticated structures, patterns or textures with complex, spontaneous multifunctionality. Among all the fascinating characteristics observed in biosystems, self-cleaning ability is regarded as one of the most interesting topics in biomimicry because of its potential applications in various fields such as aerospace, energy conversion and biomedical and environmental protection. Recently, in-depth studies have been carried out on various compelling biostructures including lotus leaves, shark skins, butterfly wings and gecko feet. To understand and mimic their self-cleaning mechanisms in artificial structures, in this article, recent progress in self-cleaning techniques is discussed and summarized. Based on the underlying self-cleaning mechanisms, the methods are classified into two categories: self-cleaning with water and without water. The review gives a succinct account of the detailed mechanisms and biomimetic processes applied to create artificial self-cleaning materials and surfaces, and provides some examples of cutting-edge applications such as anti-reflection, water repellence, self-healing, anti-fogging and micro-manipulators. The prospectives and directions of future development are also briefly proposed. PMID:27628170

  15. Biomimetic self-cleaning surfaces: synthesis, mechanism and applications

    PubMed Central

    Zhang, Wenwen; Dong, Chenbo; Sreeprasad, Theruvakkattil Sreenivasan

    2016-01-01

    With millions of years of natural evolution, organisms have achieved sophisticated structures, patterns or textures with complex, spontaneous multifunctionality. Among all the fascinating characteristics observed in biosystems, self-cleaning ability is regarded as one of the most interesting topics in biomimicry because of its potential applications in various fields such as aerospace, energy conversion and biomedical and environmental protection. Recently, in-depth studies have been carried out on various compelling biostructures including lotus leaves, shark skins, butterfly wings and gecko feet. To understand and mimic their self-cleaning mechanisms in artificial structures, in this article, recent progress in self-cleaning techniques is discussed and summarized. Based on the underlying self-cleaning mechanisms, the methods are classified into two categories: self-cleaning with water and without water. The review gives a succinct account of the detailed mechanisms and biomimetic processes applied to create artificial self-cleaning materials and surfaces, and provides some examples of cutting-edge applications such as anti-reflection, water repellence, self-healing, anti-fogging and micro-manipulators. The prospectives and directions of future development are also briefly proposed. PMID:27628170

  16. Biomimetic self-cleaning surfaces: synthesis, mechanism and applications.

    PubMed

    Xu, Quan; Zhang, Wenwen; Dong, Chenbo; Sreeprasad, Theruvakkattil Sreenivasan; Xia, Zhenhai

    2016-09-01

    With millions of years of natural evolution, organisms have achieved sophisticated structures, patterns or textures with complex, spontaneous multifunctionality. Among all the fascinating characteristics observed in biosystems, self-cleaning ability is regarded as one of the most interesting topics in biomimicry because of its potential applications in various fields such as aerospace, energy conversion and biomedical and environmental protection. Recently, in-depth studies have been carried out on various compelling biostructures including lotus leaves, shark skins, butterfly wings and gecko feet. To understand and mimic their self-cleaning mechanisms in artificial structures, in this article, recent progress in self-cleaning techniques is discussed and summarized. Based on the underlying self-cleaning mechanisms, the methods are classified into two categories: self-cleaning with water and without water. The review gives a succinct account of the detailed mechanisms and biomimetic processes applied to create artificial self-cleaning materials and surfaces, and provides some examples of cutting-edge applications such as anti-reflection, water repellence, self-healing, anti-fogging and micro-manipulators. The prospectives and directions of future development are also briefly proposed.

  17. Surface-emitting laser logic

    SciTech Connect

    Olbright, G.R.; Bryan, R.P.; Brennan, T.M.; Lear, K.; Poirier, G.E.; Fu, W.S. ); Jewell, J.L.; Lee, Y.H. )

    1990-10-31

    We describe a new class of optical logic devices which consist of integrated phototransistors and surface-emitting lasers. The devices function as optical neurons having high gain and, as arrays, are ideal for neural networks, parallel optical signal processing and optical computing applications. 3 refs., 3 figs.

  18. Laser heterodyne surface profiler

    DOEpatents

    Sommargren, G.E.

    1980-06-16

    A method and apparatus are disclosed for testing the deviation of the face of an object from a flat smooth surface using a beam of coherent light of two plane-polarized components, one of a frequency constantly greater than the other by a fixed amount to produce a difference frequency with a constant phase to be used as a reference, and splitting the beam into its two components. The separate components are directed onto spaced apart points on the face of the object to be tested for smoothness while the face of the object is rotated on an axis normal to one point, thereby passing the other component over a circular track on the face of the object. The two components are recombined after reflection to produce a reflected frequency difference of a phase proportional to the difference in path length of one component reflected from one point to the other component reflected from the other point. The phase of the reflected frequency difference is compared with the reference phase to produce a signal proportional to the deviation of the height of the surface along the circular track with respect to the fixed point at the center, thereby to produce a signal that is plotted as a profile of the surface along the circular track. The phase detector includes a quarter-wave plate to convert the components of the reference beam into circularly polarized components, a half-wave plate to shift the phase of the circularly polarized components, and a polarizer to produce a signal of a shifted phase for comparison with the phase of the frequency difference of the reflected components detected through a second polarizer. Rotation of the half-wave plate can be used for phase adjustment over a full 360/sup 0/ range.

  19. Coal surface control for advanced physical fine coal cleaning technologies

    SciTech Connect

    Morsi, B.I.; Chiang, S.H.; Sharkey, A.; Blachere, J.; Klinzing, G.; Araujo, G.; Bi, H.; Campbell, P.; Ciocco, M.; Hittle, L.; Kim, S.; Kim, Y.

    1991-01-01

    The overall objective of the project is to develop techniques for coal surface control prior to the advanced physical fine coal cleaning process of selective agglomeration in order to achieve 90% pyrite sulfur rejection at an energy recovery greater than 90% based on run-of-mine coal. The surface control is meant to encompass surface modification during grinding and laboratory beneficiation testing. The project includes the following tasks: Project planning, method for analysis of samples, development of standard beneficiation test, grinding studies, modification of particle surface, and exploratory R D and support. 5 refs., 22 figs., 34 tabs.

  20. Laser heterodyne surface profiler

    DOEpatents

    Sommargren, Gary E.

    1982-01-01

    A method and apparatus is disclosed for testing the deviation of the face of an object from a flat smooth surface using a beam of coherent light of two plane-polarized components, one of a frequency constantly greater than the other by a fixed amount to produce a difference frequency with a constant phase to be used as a reference. The beam also is split into its two components with the separate components directed onto spaced apart points onthe face of the object to be tested for smoothness. The object is rotated on an axis coincident with one component which is directed to the face of the object at the center which constitutes a virtual fixed point. This component also is used as a reference. The other component follows a circular track on the face of the object as the object is rotated. The two components are recombined after reflection to produce a reflected frequency difference of a phase proportional to the difference in path length which is compared with the reference phase to produce a signal proportional to the deviation of the height of the surface along the circular track with respect to the fixed point at the center.

  1. Laser Surface Preparation and Bonding of Aerospace Structural Composites

    NASA Technical Reports Server (NTRS)

    Belcher, M. A.; Wohl, C. J.; Hopkins, J. W.; Connell, J. W.

    2010-01-01

    Adhesive bonds are critical to the integrity of built-up structures. Disbonds can often be detected but the strength of adhesion between surfaces in contact is not obtainable without destructive testing. Typically the number one problem in a bonded structure is surface contamination, and by extension, surface preparation. Standard surface preparation techniques, including grit blasting, manual abrasion, and peel ply, are not ideal because of variations in their application. Etching of carbon fiber reinforced plastic (CFRP) panels using a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser appears to be a highly precise and promising way to both clean a composite surface prior to bonding and provide a bond-promoting patterned surface akin to peel ply without the inherent drawbacks from the same (i.e., debris and curvature). CFRP surfaces prepared using laser patterns conducive to adhesive bonding were compared to typical prebonding surface treatments through optical microscopy, contact angle goniometry, and post-bonding mechanical testing.

  2. Laser cleaning of graffiti in Rosa Porriño granite

    NASA Astrophysics Data System (ADS)

    Fiorucci, M. P.; Lamas, J.; López, A. J.; Rivas, T.; Ramil, A.

    2011-05-01

    This paper presents preliminary results in determining the optimum parameters for graffiti removal in a ornamental granite, Rosa Porriño, by means of Nd:YVO4 laser at the wavelength of 355 nm and different fluences. The spray-paints (black, blue, red and silver) tested in this work were chemically characterized by means of elemental analysis, XRF, SEM/EDX and FTIR. The assessment of cleaning and characterization of the stone substrate before and after irradiation was performed by means of optical microscopy, SEM-EDX, and confocal microscopy. The analysis of the irradiated samples showed in some cases, damage in the granite substrate associated to thermal effects. The severity and kind of damage, depends on the laser fluence delivered, the constituent mineral irradiated, and the color used to paint the stone. So, at the highest levels of fluence the laser beam is able to scratch the surface, being the depth of the grooves in the stone measured by confocal microscopy. Moreover, SEM images show the differential damage caused in mineral constituents of granite i.e., quartz, feldspars, and biotite, the latter providing to be the most affected mineral, reaching melting even at low levels of fluence. It was appreciated that the color of the spray-paint affects the results of cleaning, and observed differences could be attributed to different organic constituents in the paints or the presence of metallic particles in its composition, as occurs with silver paint.

  3. Laser ablation of contaminants from concrete and metal surfaces. Topical report, June--December 1994

    SciTech Connect

    Freiwald, J.; Freiwald, D.A.

    1994-12-01

    Tests have demonstrated that it is possible to clean coatings off surfaces using high-power, pulsed, high-repetition-rate lasers. Purpose of this contract is to demonstrate (1) that pulsed-repetition lasers can be used to remove paint from concrete and metal surfaces, including cleaning out the surface pores, (2) that the cleaning process will result in negligible release of contaminated ablated material to the environment, and (3) that the process generates negligible additional waste compared to competing technologies. This report covers technical progress during Phase 1 of the contract and makes recommendations for technology development in Phase 2.

  4. Bioinspired superhydrophobic, self-cleaning and low drag surfaces

    NASA Astrophysics Data System (ADS)

    Bhushan, Bharat

    2013-09-01

    Nature has evolved objects with desired functionality using commonly found materials. Nature capitalizes on hierarchical structures to achieve functionality. The understanding of the functions provided by objects and processes found in nature can guide us to produce nanomaterials, nanodevices, and processes with desirable functionality. This article provides an overview of four topics: (1) Lotus Effect used to develop superhydrophobic and self-cleaning/antifouling surfaces with low adhesion, (2) Shark Skin Effect to develop surfaces with low fluid drag and anti-fouling characteristics, and (3-4) Rice Leaf and Butterfly Wing Effect to develop superhydrophobic and self-cleaning surfaces with low drag. Rice Leaf and Butterfly Wings combine the Shark Skin and Lotus Effects.

  5. Impact of different cleaning processes on the laser damage threshold of antireflection coatings for Z-Backlighter optics at Sandia National Laboratories

    NASA Astrophysics Data System (ADS)

    Field, Ella; Bellum, John; Kletecka, Damon

    2014-12-01

    We have examined how three different cleaning processes affect the laser-induced damage threshold (LIDT) of antireflection coatings for large dimension, Z-Backlighter laser optics at Sandia National Laboratories. Laser damage thresholds were measured after the coatings were created, and again 4 months later to determine which cleaning processes were most effective. Coatings that received cleaning exhibited the highest LIDTs compared to coatings that were not cleaned. In some cases, there is nearly a twofold increase in the LIDT between the cleaned and uncleaned coatings (19.4 J/cm2 compared to 39.1 J/cm2). Higher LIDTs were realized after 4 months of aging. The most effective cleaning process involved washing the coated surface with mild detergent, and then soaking the optic in a mixture of ethyl alcohol and deionized water. Also, the laser damage results indicate that the presence of nonpropagating (NP) damage sites dominates the LIDTs of almost every optic, despite the cleaning process used. NP damage sites can be attributed to defects such as nodules in the coating or surface contamination, which suggests that pursuing further improvements to the deposition or cleaning processes are worthwhile to achieve even higher LIDTs.

  6. Influence of cleaning process on the laser-induced damage threshold of substrates

    SciTech Connect

    Shen Zhengxiang; Ding Tao; Ye Xiaowen; Wang Xiaodong; Ma Bin; Cheng Xinbin; Liu Huasong; Ji Yiqin; Wang Zhanshan

    2011-03-20

    The cleaning process of optical substrates plays an important role during the manufacture of high-power laser coatings. Two kinds of substrates, fused silica and BK7 glass, and two cleaning processes, called process 1 and process 2 having different surfactant solutions and different ultrasonic cleaning parameters, are adopted to compare the influence of the ultrasonic cleaning technique on the substrates. The evaluation standards of the cleaning results include contaminant-removal efficiency, weak absorption, and laser-induced damage threshold of the substrates. For both fused silica and BK7, process 2 is more efficient than process 1. Because acid and alkaline solutions can increase the roughness of BK7, process 2 is unsuitable for BK7 glass cleaning. The parameters of the cleaning protocol should be changed depending on the material of the optical components and the type of contamination.

  7. Influence of cleaning process on the laser-induced damage threshold of substrates.

    PubMed

    Shen, Zhengxiang; Ding, Tao; Ye, Xiaowen; Wang, Xiaodong; Ma, Bin; Cheng, Xinbin; Liu, Huasong; Ji, Yiqin; Wang, Zhanshan

    2011-03-20

    The cleaning process of optical substrates plays an important role during the manufacture of high-power laser coatings. Two kinds of substrates, fused silica and BK7 glass, and two cleaning processes, called process 1 and process 2 having different surfactant solutions and different ultrasonic cleaning parameters, are adopted to compare the influence of the ultrasonic cleaning technique on the substrates. The evaluation standards of the cleaning results include contaminant-removal efficiency, weak absorption, and laser-induced damage threshold of the substrates. For both fused silica and BK7, process 2 is more efficient than process 1. Because acid and alkaline solutions can increase the roughness of BK7, process 2 is unsuitable for BK7 glass cleaning. The parameters of the cleaning protocol should be changed depending on the material of the optical components and the type of contamination.

  8. Comparative evaluation of UV-vis-IR Nd:YAG laser cleaning of beeswax layers on granite substrates

    NASA Astrophysics Data System (ADS)

    Pan, A.; Chiussi, S.; González, P.; Serra, J.; León, B.

    2011-04-01

    The beeswax treatment applied in the sixties to prevent rain water from penetrating the outer stone surface of valuable granitic Galician monuments is contributing to the acceleration of the superficial degradation process of these monuments. At present, the northern sector of the renaissance frieze in the Cloister of the Cathedral of Santiago de Compostela is one of the most representative examples. Conventional wax removal methods (water, chemical and mechanical cleaning) can possibly destruct important details of the relief. Therefore laser removal is considered as a good alternative. In this work, we report systematic investigations of the effect of laser cleaning at different Nd:YAG laser wavelengths (266, 355, 532 and 1064 nm) on representative samples of the real historical surfaces. Laser removal of beeswax on granite at neither of the four wavelengths of the Nd:YAG laser is not a layer by layer removal process. For each irradiance and wavelength there is a maximum thickness that can be completely removed by a single pulse. Above this thickness the waxy material is not removed, although it undergoes thermal modifications; since the fraction of radiation that reaches the granite substrate is not enough to trigger the ejection of material. Our results show that the wax-granite interface plays a fundamental role in granite cleaning, and when the wax is weakened by absorption of radiation at 266 nm, the removal process becomes more efficient.

  9. Fabrication of microgrooves on a curved surface by the confocal measurement system using pulse laser and continuous laser

    NASA Astrophysics Data System (ADS)

    Noh, Jiwhan; Cho, Ilhwan; Lee, Seungwoo; Na, Suckjoo; Lee, Jae-Hoon

    2012-03-01

    In order to fabricate microgrooves on a curved surface, the curved surface was measured with a confocal system and then it was used for laser microprocessing. This paper proposes a new method of using a pulse laser for the confocal system to measure the curved surface. It also compares the conventional way of using a continuous laser and a new way of using the pulse laser with the confocal system. Using the data measured with the pulse laser for fabrication, microgrooves were fabricated on a curved surface. The width of the fabricated microgroove was 10 μm and the depth was 27 μm. The microgroove fabricated on a curved surface as a part of this study can be used in injection molding to manufacture a micropatterned plastic surface at a low cost. This plastic surface can be applied for a superhydrophobic surface, a self-cleaning surface, or a biochip.

  10. Laser cleaning of parchment: structural, thermal and biochemical studies into the effect of wavelength and fluence

    NASA Astrophysics Data System (ADS)

    Kennedy, Craig J.; Vest, Marie; Cooper, Martin; Wess, Tim J.

    2004-04-01

    Laser cleaning of parchment is a novel technique that has the potential to provide contactless, chemical-free cleaning of historically important documents. However, the effect of laser cleaning on the collagenous structure of parchment is still poorly understood, as is the effect of the wavelength or the energy density (fluence level) used to clean parchment. In this study, small angle X-ray scattering (SAXS), shrinkage temperature (Ts) measurements by the micro hot table technique and SDS-polyacrylamide gel electrophoresis (SDS-PAGE) of parchment samples after laser cleaning reveal the effect of cleaning to the structural, thermal and molecular characteristics of parchment, respectively. The effect of cleaning at infrared (1064 nm), green (532 nm) and ultraviolet (266 nm) wavelengths at a range of fluence levels is investigated. SAXS is used to investigate the removal of dirt from parchment. Laser cleaning at IR or green wavelengths appears not to alter the collagen diffraction pattern from SAXS, the shrinkage activity or shrinkage temperature from Ts measurements or the molecular integrity of parchment as shown by SDS-PAGE. However, parchments cleaned at the ultraviolet wavelength display structural damage and a reduction in hydrothermal stability and molecular integrity.

  11. Micro-structural characterization of black crust and laser cleaning of building stones by micro-Raman and SEM techniques.

    PubMed

    Potgieter-Vermaak, S S; Godoi, R H M; Grieken, R Van; Potgieter, J H; Oujja, M; Castillejo, M

    2005-09-01

    Research concerning the formation and removal of black crusts on various historical objects is approached from many different angles. The so-called "yellowing effect", observed after laser treatment for cleaning purposes, has also received a lot of attention. Evidence regarding this phenomenon differs considerably and the actual mechanisms are still speculated on by researchers. In an attempt to elucidate the processes involved in the yellowing effect associated with laser cleaning, a new analytical technique has been used to investigate the black crust, a region of the sample cleaned by laser irradiation at 1064 nm and another region of the same sample subjected to further laser irradiation at 355 nm, on a limestone sample from the cathedral of Seville in Spain. Micro-Raman spectrometry offers the advantage of spatial chemical characterization of the stone, based upon its molecular makeup and was performed on the bulk body of the stone. Raman and scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDXS) results indicate that the surfaces cleaned by irradiation at 1064 nm and by double irradiation at 1064 and 355 nm differed in terms of their calcium sulphate, calcium oxalate and iron oxide content, and that this could contribute to the difference in colour observed.

  12. Evaluation of surface sampling method performance for Bacillus Spores on clean and dirty outdoor surfaces.

    SciTech Connect

    Wilson, Mollye C.; Einfeld, Wayne; Boucher, Raymond M.; Brown, Gary Stephen; Tezak, Matthew Stephen

    2011-06-01

    Recovery of Bacillus atrophaeous spores from grime-treated and clean surfaces was measured in a controlled chamber study to assess sampling method performance. Outdoor surfaces investigated by wipe and vacuum sampling methods included stainless steel, glass, marble and concrete. Bacillus atrophaeous spores were used as a surrogate for Bacillus anthracis spores in this study designed to assess whether grime-coated surfaces significantly affected surface sampling method performance when compared to clean surfaces. A series of chamber tests were carried out in which known amounts of spores were allowed to gravitationally settle onto both clean and dirty surfaces. Reference coupons were co-located with test coupons in all chamber experiments to provide a quantitative measure of initial surface concentrations of spores on all surfaces, thereby allowing sampling recovery calculations. Results from these tests, carried out under both low and high humidity conditions, show that spore recovery from grime-coated surfaces is the same as or better than spore recovery from clean surfaces. Statistically significant differences between method performance for grime-coated and clean surfaces were observed in only about half of the chamber tests conducted.

  13. Surface Finish after Laser Metal Deposition

    NASA Astrophysics Data System (ADS)

    Rombouts, M.; Maes, G.; Hendrix, W.; Delarbre, E.; Motmans, F.

    Laser metal deposition (LMD) is an additive manufacturing technology for the fabrication of metal parts through layerwise deposition and laser induced melting of metal powder. The poor surface finish presents a major limitation in LMD. This study focuses on the effects of surface inclination angle and strategies to improve the surface finish of LMD components. A substantial improvement in surface quality of both the side and top surfaces has been obtained by laser remelting after powder deposition.

  14. Surface contamination initiated laser damage

    SciTech Connect

    Feit, M.D.; Rubenchick, A.M.; Faux, D.R.

    1997-01-24

    We are engaged in a comprehensive effort to understand and model the initiation and growth of laser damage initiated by surface contaminants. This includes, for example, the initial absorption by the contaminant, heating and plasma generation, pressure and thermal loading of the transparent substrate, and subsequent shockwave propagation, ``splashing`` of molten material and possible spallation, optical propagation and scattering, and treatment of material fracture. The integration use of large radiation hydrodynamics codes, optical propagation codes and material strength codes enables a comprehensive view of the damage process The following picture of surface contaminant initiated laser damage is emerging from our simulations. On the entrance optical surface, small particles can ablate nearly completely. In this case, only relatively weak shockwaves are launched into the substrate, but some particulate material may be left on the surface to act as a diffraction mask and cause further absorption. Diffraction by wavelength scale scattering centers can lead to significant intensity modulation. Larger particles will not be completely vaporized. The shockwave generated in this case 1642is larger and can lead to spallation of contaminant material which then may be deposited in the substrate. A gaseous atmosphere can lead to radiation trapping with concomitant increases in temperature and pressure near the surface. In addition, supersonic ionization waves in air may be generated which greatly extend the plasma plume spatially and temporally. Contaminants on the exit optical surface behave differently. They tend to heat and pop off completely in which case significant damage may not occur. Since plasma formed at the interface of the optic and absorbing particle is confined, much stronger pressures are generated in this case. Imaging of contaminants resulting in ``writing`` a diffraction pattern on the exit surface due to contamination on the entrance surface has been

  15. Surface Decontamination Using Laser Ablation Process - 12032

    SciTech Connect

    Moggia, Fabrice; Lecardonnel, Xavier; Damerval, Frederique

    2012-07-01

    A new decontamination method has been investigated and used during two demonstration stages by the Clean-Up Business Unit of AREVA. This new method is based on the use of a Laser beam to remove the contaminants present on a base metal surface. In this paper will be presented the type of Laser used during those tests but also information regarding the efficiency obtained on non-contaminated (simulated contamination) and contaminated samples (from the CEA and La Hague facilities). Regarding the contaminated samples, in the first case, the contamination was a quite thick oxide layer. In the second case, most of the contamination was trapped in dust and thin grease layer. Some information such as scanning electron microscopy (SEM), X-Ray scattering spectroscopy and decontamination factors (DF) will be provided in this paper. Laser technology appears to be an interesting one for the future of the D and D applications. As shown in this paper, the results in terms of efficiency are really promising and in many cases, higher than those obtained with conventional techniques. One of the most important advantages is that all those results have been obtained with no generation of secondary wastes such as abrasives, chemicals, or disks... Moreover, as mentioned in introduction, the Laser ablation process can be defined as a 'dry' process. This technology does not produce any liquid waste (as it can be the case with chemical process or HP water process...). Finally, the addition of a vacuum system allows to trap the contamination onto filters and thus avoiding any dissemination in the room where the process takes place. The next step is going to be a commercial use in 2012 in one of the La Hague buildings. (authors)

  16. Laser cleaning of works of art: evaluation of the thermal stress induced by Er:YAG laser

    NASA Astrophysics Data System (ADS)

    De Cruz, A.; Andreotti, A.; Ceccarini, A.; Colombini, M. P.

    2014-06-01

    The Er:YAG laser has proven particularly efficient in cleaning procedures of works of art. The removal of the superficial deposits is achieved through melting, thermal decomposition and evaporation. However, the energy absorbed by vibrational modes is dissipated as heat, increasing the temperature of the surface coating that could cause damage on the object. The aim of this study was to evaluate the temperature increase induced by a Er:YAG MonaLaser (LLC., Orlando, FL, USA). To that purpose, we designed a dedicated device to perform the tests in an inert atmosphere or with a wetting agent, to measure the radiant energy per laser pulse. Tests were carried out both on graphite, which absorbs IR radiation and showed a very intense flash emission, and on different kind of samples representative of materials with different levels of conductivity and thermal diffusivity. Results obtained showed that the temperature increase in the irradiated surface depends on the substrate but never causes the damage of the organic and inorganic material. The use of a solvent as wetting agent has been also tested.

  17. Cleaning painted surfaces: evaluation of leaching phenomenon induced by solvents applied for the removal of gel residues.

    PubMed

    Casoli, Antonella; Di Diego, Zaira; Isca, Clelia

    2014-12-01

    Cleaning is one of the most important, delicate, and at the same time controversial processes in the conservation treatment of paintings. Although a strict definition of cleaning would be the removal of dirt, grime, or other accretions (surface cleaning), in the conservation field, cleaning is used in the broader meaning to include thinning/removing altered or “unwanted layers” of materials without damaging or altering the physicochemical properties of the surfaces to be preserved. The cleaning of unvarnished paintings is one of the most critical issues that are currently discussed. Several studies exist regarding different cleaning tools, such as gels, soaps, enzymes, ionic liquids, and foams, as well as various dry methods and lasers, but only a few have been performed on the risk associated with the use of water and organic solvents for the cleaning treatments in relation to the original paint binder. The aim of the study is to verify analytically the behavior of water gelling agents during cleaning treatments and the interaction of the following elements: water or organic solvents applied for the removal of gel residues with the original lipid paint binder. For this purpose, the study was conducted on a fragment of canvas painting (sixteenth to seventeenth century) of Soprintendenza per i Beni Storici, Artistici ed Etnoantropologici del Friuli Venezia Giulia (Superintendence for the Historical, Artistic and Ethno-anthropological Heritage of Friuli Venezia Giulia), Udine by means of Fourier transform infrared spectroscopy, gas chromatography/mass spectrometry, and scanning electron microscopy. PMID:24659401

  18. Cleaning Dirty Surfaces: A Three-Body Problem.

    PubMed

    Stoehr, Bastian; Hall, Colin; Evans, Drew; Murphy, Peter

    2016-07-20

    Human interaction with touch screens requires physical touch and hence results in contamination of these surfaces, resulting in the necessity of cleaning. In this study we discuss the three bodies of this problem and how each component contributes and can be controlled. Utilizing a standard fingerprint machine and a standard cleanability test, this study examines the influence of parameters such as the wiping speed and pressure, the material and surface area of the cloths, and the surface energy of the contaminated surfaces. It was shown that fingerprint contamination undergoes shear banding and hence is not easily removed. The degree of material removal depends on the position of the shear plane, which is influenced by surface energies and shear rates. PMID:27351355

  19. Cleaning Dirty Surfaces: A Three-Body Problem.

    PubMed

    Stoehr, Bastian; Hall, Colin; Evans, Drew; Murphy, Peter

    2016-07-20

    Human interaction with touch screens requires physical touch and hence results in contamination of these surfaces, resulting in the necessity of cleaning. In this study we discuss the three bodies of this problem and how each component contributes and can be controlled. Utilizing a standard fingerprint machine and a standard cleanability test, this study examines the influence of parameters such as the wiping speed and pressure, the material and surface area of the cloths, and the surface energy of the contaminated surfaces. It was shown that fingerprint contamination undergoes shear banding and hence is not easily removed. The degree of material removal depends on the position of the shear plane, which is influenced by surface energies and shear rates.

  20. Surface-emitting fiber lasers

    NASA Astrophysics Data System (ADS)

    Shapira, Ofer; Kuriki, Ken; Orf, Nicholas D.; Abouraddy, Ayman F.; Benoit, Gilles; Viens, Jean F.; Rodriguez, Alejandro; Ibanescu, Mihai; Joannopoulos, John D.; Fink, Yoel; Brewster, Megan M.

    2006-05-01

    All fiber lasers to date emit radiation only along the fiber axis. Here a fiber that exhibits laser emission that is radially directed from its circumferential surface is demonstrated. A unique and controlled azimuthally anisotropic optical wave front results from the interplay between a cylindrical photonic bandgap fiber resonator, anisotropic organic dye gain, and a linearly polarized axial pump. Low threshold (86nJ) lasing at nine different wavelengths is demonstrated throughout the visible and near-infrared spectra. We also report the experimental realization of unprecedented layer thicknesses of 29.5 nm maintained throughout meter-long fibers. Such a device may have interesting medical applications ranging from photodynamic therapy to in vivo molecular imaging, as well as textile fabric displays.

  1. Coal surface control for advanced physical fine coal cleaning technologies

    SciTech Connect

    Morsi, B.I.; Chiang, S.H.; Sharkey, A.; Blachere, J.; Klinzing, G.; Araujo, G.; Cheng, Y.S.; Gray, R.; Streeter, R.; Bi, H.; Campbell, P.; Chiarlli, P.; Ciocco, M.; Hittle, L.; Kim, S.; Kim, Y.; Perez, L.; Venkatadri, R.

    1992-01-01

    This final report presents the research work carried out on the Coal Surface Control for Advanced Physical Fine Coal Cleaning Technologies project, sponsored by the US Department of Energy, Pittsburgh Energy Technology Center (DOE/PETC). The project was to support the engineering development of the selective agglomeration technology in order to reduce the sulfur content of US coals for controlling SO[sub 2] emissions (i.e., acid rain precursors). The overall effort was a part of the DOE/PETCs Acid Rain Control Initiative (ARCI). The overall objective of the project is to develop techniques for coal surface control prior to the advanced physical fine coal cleaning process of selective agglomeration in order to achieve 85% pyrite sulfur rejection at an energy recovery greater than 85% based on run-of-mine coal. The surface control is meant to encompass surface modification during grinding and laboratory beneficiation testing. The project includes the following tasks: Project planning; methods for analysis of samples; development of standard beneficiation test; grinding studies; modification of particle surface; and exploratory R D and support. The coal samples used in this project include three base coals, Upper Freeport - Indiana County, PA, Pittsburgh NO. 8 - Belmont County, OH, and Illinois No. 6 - Randolph County, IL, and three additional coals, Upper Freeport - Grant County- WV, Kentucky No. 9 Hopkins County, KY, and Wyodak - Campbell County, WY. A total of 149 drums of coal were received.

  2. Cleaning of Painted Surfaces and Examination of Cleaning by 3D-Measurement Technology at the August Deusser Museum, Zurzach

    NASA Astrophysics Data System (ADS)

    Eipper, P.-B.; Frankowski, G.

    Grime and dirt are hazards to oil paint surfaces. To remove these impurities, paintings are usually cleaned dry, or wet with surfactants in aqueous medium. Historic paint material (oil-wax colors produced by Schoenfeld Lukas, Düsseldorf) used by the Rhenish painter August Deusser (1870-1942) were obtained and studied. To examine the effects of different cleaning methods, paint surfaces were treated dry and wet. The surfaces of the treated paints were examined by 3D-measuring technology. This new, transportable technology provides measurements in seconds during the cleaning process and produces measurable images that show changes on the surface and craquelure. Some aqueous cleaning systems can increase craquelure up to five times as much as dry cleaning methods on oil paint surfaces. However, dry methods are not sufficient to completely clean the surfaces. Therefore, modification of aqueous cleaning methods are necessary and include using mild nonionic surfactants, thickening of the solutions used, reduction of contact humidity, and increasing temperature and, pH.

  3. Modeling of surface cleaning by cavitation bubble dynamics and collapse.

    PubMed

    Chahine, Georges L; Kapahi, Anil; Choi, Jin-Keun; Hsiao, Chao-Tsung

    2016-03-01

    Surface cleaning using cavitation bubble dynamics is investigated numerically through modeling of bubble dynamics, dirt particle motion, and fluid material interaction. Three fluid dynamics models; a potential flow model, a viscous model, and a compressible model, are used to describe the flow field generated by the bubble all showing the strong effects bubble explosive growth and collapse have on a dirt particle and on a layer of material to remove. Bubble deformation and reentrant jet formation are seen to be responsible for generating concentrated pressures, shear, and lift forces on the dirt particle and high impulsive loads on a layer of material to remove. Bubble explosive growth is also an important mechanism for removal of dirt particles, since strong suction forces in addition to shear are generated around the explosively growing bubble and can exert strong forces lifting the particles from the surface to clean and sucking them toward the bubble. To model material failure and removal, a finite element structure code is used and enables simulation of full fluid-structure interaction and investigation of the effects of various parameters. High impulsive pressures are generated during bubble collapse due to the impact of the bubble reentrant jet on the material surface and the subsequent collapse of the resulting toroidal bubble. Pits and material removal develop on the material surface when the impulsive pressure is large enough to result in high equivalent stresses exceeding the material yield stress or its ultimate strain. Cleaning depends on parameters such as the relative size between the bubble at its maximum volume and the particle size, the bubble standoff distance from the particle and from the material wall, and the excitation pressure field driving the bubble dynamics. These effects are discussed in this contribution.

  4. Surface metrology using laser trackers

    NASA Astrophysics Data System (ADS)

    Enriquez, Rogerio; Sampieri, Cesar E.

    2005-02-01

    During the process of manufacture or measuring large components, position and orientation are needed thus; a method based in surveying the surface can be used to describe them. This method requires an ensemble of measurements of fixed points whose coordinates are unknown. Afterwards resulting observations are manipulated to determinate objects position in order to apply surface metrology. In this work, a methodology to reduce uncertainties in surface measuring is presented. When measuring large surfaces, numerical methods can reduce uncertainties in the measures, and this can be done with instruments as such as the Laser Tracker (LT). Calculations use range and angles measures, in order to determinate the coordinates of tridimensional unknown positions from differents surveying points. The purpose of this work, is to solve problems of surface metrology with given tolerances; with advantages in resources and results, instead of making time sacrifices. Here, a hybrid methodology is developed, combining Laser Tracker with GPS theories and analysis. Such a measuring position system can be used in applications where the use of others systems are unpractical, mainly because this kind of measuring instruments are portables and capable to track and report results in real-time, it can be used in virtually anyplace. Simulations to measure panels for the Large Millimetric Telescope (LMT/GTM) in Mexico were done. A first benefit from using this method is that instrument is not isolated from its measuring environment. Instead, the system is thought as a whole with operator, measuring environment and targets. This solution provides an effective way, and a more precise measurement, because it does optimize the use of the instrument and uses additional information to strength the solution.

  5. Laser Surface Hardening of AISI 1045 Steel

    NASA Astrophysics Data System (ADS)

    Li, Ruifeng; Jin, Yajuan; Li, Zhuguo; Qi, Kai

    2014-09-01

    The study investigates laser surface hardening in the AISI 1045 steel using two different types of industrial laser: a high-power diode laser (HPDL) and a CO2 laser, respectively. The effect of process parameters such as beam power, travel speed on structure, case depth, and microhardness was examined. In most cases, a heat-affected zone (HAZ) formed below the surface; a substantial increase in surface hardness was achieved. In addition, big differences were found between the hardened specimens after HPDL surface hardening and CO2 laser surface hardening. For HPDL, depths of the HAZ were almost equal in total HAZ o, without surface melting. For CO2 laser, the depths changed a lot in the HAZ, with surface melting in the center. To better understand the difference of laser hardening results when use these two types of laser, numerical (ANSYS) analysis of the heat conduction involved in the process was also studied. For HPDL method, a rectangular beam spot and uniform energy distribution across the spot were assumed, while for CO2 laser, a circular beam spot and Gaussian energy distribution were assumed. The results showed that the energy distribution variety altered the thermal cycles of the HAZ dramatically. The rectangular HPDL laser beam spot with uniform energy distribution is much more feasible for laser surface hardening.

  6. Nd:YVO4 laser removal of graffiti from granite. Influence of paint and rock properties on cleaning efficacy

    NASA Astrophysics Data System (ADS)

    Rivas, T.; Pozo, S.; Fiorucci, M. P.; López, A. J.; Ramil, A.

    2012-12-01

    This paper presents the cleaning efficiency results for four differently coloured graffiti paints applied to two types of granitic stone by Nd:YVO4 laser at 355 nm. The paints were characterized in terms of mineralogy and chemistry using x-ray fluorescence, X-ray diffraction, Fourier transform infrared (FTIR) spectroscopy and scanning electron microscope (SEM); paint absorbance in the ultraviolet-visible-infrared range (200-2000 nm) was also assessed. The studied granites had different mineralogy, texture and porosity properties. Cleaning efficiency was evaluated by polarized microscopy, SEM, FTIR spectroscopy and spectrophotometer colour measurements. The results indicate differences in the effectiveness of surface cleaning for the blue, red and black paints as opposed to the silver paint, mainly attributed to chemical composition. No evidence was found that the granite properties had a bearing on laser effectiveness, although the degree, type and spatial distribution of transgranular fissures in the stone affected the overall assessment of cleaning effectiveness. Polarized light microscopy observations and colour measurements showed that the intensity and distribution of fissures affect the depth of paint penetration, ultimately affecting the cleaning efficiency for both granites.

  7. Resolution of contamination problems affecting Laser-Surface-Certification inspection

    SciTech Connect

    Jackson, L.C.

    1982-03-01

    Contamination from particulate and organic residues has interfered with the Laser Surface Certification (LSC) inspection of some parts, subsequently preventing their certification to the Ernest Orlando Lawrence Livermore National Laboratory (LLNL) product specification. Contamination was found to come from three sources: particulate and organic residues from polishing compounds; organic films from cleaning solvents; and particles and organic residues transferred from plastic fixtures used to process these parts. The manufacturing cleaning process was not effective in removing all polishing compound residues, and an extensive cleaning procedure was developed using two solvents in a multicycle ultrasonic/vapor degreasing procedure. Parts were then subjected to gas plasma cleaning which removed the organic films left by the solvent cleaning. Plastic and rubber materials were evaluated for their contamination transfer characteristics; a fluorocarbon elastomer was the least contaminating. Inspection data established the efficacy of the cleaning procedure. After design relaxation, Bendix Kansas City was able to rely on a single-stage ultrasonic vapor degreasing process to achieve product acceptance.

  8. Recommended values of clean metal surface work functions

    SciTech Connect

    Derry, Gregory N. Kern, Megan E.; Worth, Eli H.

    2015-11-15

    A critical review of the experimental literature for measurements of the work functions of clean metal surfaces of single-crystals is presented. The tables presented include all results found for low-index crystal faces except cases that were known to be contaminated surfaces. These results are used to construct a recommended value of the work function for each surface examined, along with an uncertainty estimate for that value. The uncertainties are based in part on the error distribution for all measured work functions in the literature, which is included here. The metals included in this review are silver (Ag), aluminum (Al), gold (Au), copper (Cu), iron (Fe), iridium (Ir), molybdenum (Mo), niobium (Nb), nickel (Ni), palladium (Pd), platinum (Pt), rhodium (Rh), ruthenium (Ru), tantalum (Ta), and tungsten (W)

  9. Apparatus for in situ cleaning of carbon contaminated surfaces

    DOEpatents

    Klebanoff, Leonard E.; Grunow, Philip; Graham, Jr., Samuel

    2004-08-10

    Activated gaseous species generated adjacent a carbon contaminated surface affords in-situ cleaning. A device for removing carbon contamination from a surface of the substrate includes (a) a housing defining a vacuum chamber in which the substrate is located; (b) a source of gaseous species; and (c) a source of electrons that are emitted to activate the gaseous species into activated gaseous species. The source of electrons preferably includes (i) a filament made of a material that generates thermionic electron emissions; (ii) a source of energy that is connected to the filament; and (iii) an electrode to which the emitted electrons are attracted. The device is particularly suited for photolithography systems with optic surfaces, e.g., mirrors, that are otherwise inaccessible unless the system is dismantled.

  10. Paint removal and surface cleaning using ice particles

    NASA Astrophysics Data System (ADS)

    Foster, Terry; Visaisouk, S.

    1993-03-01

    Research into the possibility of using ice particles as a blast medium was first initiated at Defence Research Establishment Pacific (DREP) in an effort to develop a more environmentally acceptable paint removal method. A paint removal process was also required that could be used in areas where normal grit blasting could not be used due to the possibility of the residual blasting grit contaminating machinery and other equipment. As a result of this research a commercial ice blasting system was developed by RETECH. This system is now being used to remove paint from substrates that cannot be easily blasted by conventional techniques and also to clean soiled or contaminated surfaces. The problems involved in the development of an ice blast system, and its components and their functions are described. Due to the complexity of paint removal using ice blasting, parameters such as air pressure, ice particle size and ice particle flow rate were studied and adjusted to suit the nature of the particular coating and substrate of interest. The mechanism of paint removal by ice particles has also been investigated. A theoretical model has been developed to explain the different paint removal mechanisms such as erosion by abrasion and erosion by fracture as they relate to ice blasting. Finally, the use of ice blasting to removal paint from a variety of substrates is presented as well as examples of surface cleaning and surface decontamination.

  11. Paint removal and surface cleaning using ice particles

    NASA Astrophysics Data System (ADS)

    Foster, Terry; Visaisouk, S.

    1995-04-01

    Research into the possibility of using ice particles as a blast medium was first initiated at Defence Research Establishment Pacific (DREP) in an effort to develop a more environmentally acceptable paint removal method. A paint removal process was also required that could be used in areas where normal grit blasting could not be used due to the possibility of the residual blasting grit contaminating machinery and other equipment. As a result of this research a commercial ice blasting system was developed by RETECH. This system is now being used to remove paint from substrates that cannot be easily blasted by conventional techniques and also to clean soiled or contaminated surfaces. The problems involved in the development of an ice blast system and its components and their functions are described. Due to the complexity of paint removal using ice blasting, parameters such as air pressure, ice particle size and ice particle flow rate were studied and adjusted to suit the nature of the particular coating and substrate of interest. The mechanism of paint removal by ice particles has also been investigated. A theoretical model has been developed to explain the different paint removal mechanisms such as erosion by abrasion and erosion by fracture as they relate to ice blasting. Finally, the use of ice blasting to removal paint from a variety of substrates is presented as well as examples of surface cleaning and surface decontamination.

  12. Surface magnetic enhancement for coal cleaning. Final report

    SciTech Connect

    Hwang, J.Y.

    1992-10-01

    The program consisted of a fundamental study to define the chemistry for the interactions between magnetic reagent and mineral and coal particles, a laboratory study to determine the applicability of this technology on coal cleaning, and a parameter study to evaluate the technical and economical feasibility of this technology for desulfurization and de-ashing under various processing schemes. Surface magnetic enhancement using magnetic reagent is a new technology developed at the Institute. This technology can be applied to separate pyrite and other minerals particles from coal with a magnetic separation after adsorbing magnetic reagent on the surface of pyrite and other minerals particles. Particles which have absorbed magnetic reagent are rendered magnetic. The adsorption can be controlled to yield selectivity. Thus, the separation of traditionally nonmagnetic materials with a magnetic separator can be achieved. Experiments have been performed to demonstrate the theoretical fundamentals and the applications of the technology. Adsorbability, adsorption mechanisms, and adsorption selectivity are included in the fundamental study. The effects of particle size, magnetic reagent dosage, solid contents, magnetic matrix, applied magnetic field strengths, retention times, and feed loading capacities are included in the application studies. Three coals, including Illinois No. 6, Lower Kittanning and Pocahontas seams, have been investigated. More than 90% pyritic sulfur and ash reductions have been achieved. Technical and economic feasibilities of this technology have been demonstrated in this study. Both are competitive to that of the froth flotation approach for coal cleaning.

  13. Multipulse nanosecond laser modification of steel surface

    NASA Astrophysics Data System (ADS)

    Chumakov, A. N.; Nikonchuk, I. S.; Gaković, B.; Petrović, S.; Trtica, M.

    2014-09-01

    Results of surface modification are presented for MnNiCrMo-steel samples exposed to a Nd:YAG laser operating in a pulse-periodic mode (10 Hz frequency, 532 nm wavelength and 17 ns pulse duration). The steel samples were irradiated in air by a series of laser pulses at a fluence of 10.7 J cm-2 close to a plasma formation threshold. Surface structures were examined by optical, scanning electron and confocal optical microscopy. The appearance of the detected surface structures strongly depends on the number of laser pulses and power density of laser radiation. Significant differences were found between laser-induced structures in the center of the laser spot, at its edges and in the nearest surrounding of the laser spot. The reasons for such differences are discussed.

  14. Active cleaning technique for removing contamination from optical surfaces in space

    NASA Technical Reports Server (NTRS)

    Shannon, R. L.; Gillette, R. B.; Cruz, G. A.

    1973-01-01

    An active cleaning technique for removing contaminants from optical surfaces in space was investigated with emphasis on the feasibility of using plasma exposure as a means of in-situ cleaning. The major work accomplished includes: (1) development of an in-situ reflectometer for use in conjunction with the contaminant film deposition/cleaning facility; (2) completion of Apollo Telescope Mount (ATM) filter treatment experiments to assess the effects of plasma exposure on the UV transmittance; (3) attempts to correlate the atomic oxygen flux with cleaning rate; (4) completion of in-situ butadien contamination/plasma cleaning/UV reflectance measurement experiments; (5) carbon cleaning experiments using various gases; (6) completion of silicone contamination/cleaning experiments; and (7) experiments conducted at low chamber pressures to determine cleaning rate distribution and contamination of surfaces adjacent to those being cleaned.

  15. Laser surface texturing of tool steel: textured surfaces quality evaluation

    NASA Astrophysics Data System (ADS)

    Šugár, Peter; Šugárová, Jana; Frnčík, Martin

    2016-05-01

    In this experimental investigation the laser surface texturing of tool steel of type 90MnCrV8 has been conducted. The 5-axis highly dynamic laser precision machining centre Lasertec 80 Shape equipped with the nano-second pulsed ytterbium fibre laser and CNC system Siemens 840 D was used. The planar and spherical surfaces first prepared by turning have been textured. The regular array of spherical and ellipsoidal dimples with a different dimensions and different surface density has been created. Laser surface texturing has been realized under different combinations of process parameters: pulse frequency, pulse energy and laser beam scanning speed. The morphological characterization of ablated surfaces has been performed using scanning electron microscopy (SEM) technique. The results show limited possibility of ns pulse fibre laser application to generate different surface structures for tribological modification of metallic materials. These structures were obtained by varying the processing conditions between surface ablation, to surface remelting. In all cases the areas of molten material and re-cast layers were observed on the bottom and walls of the dimples. Beside the influence of laser beam parameters on the machined surface quality during laser machining of regular hemispherical and elipsoidal dimple texture on parabolic and hemispherical surfaces has been studied.

  16. Solid Lubrication Fundamentals and Applications. Properties of Clean Surfaces: Adhesion, Friction, and Wear

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    1998-01-01

    This chapter presents the adhesion, friction, and wear behaviors of smooth, atomically clean surfaces of solid-solid couples, such as metal-ceramic couples, in a clean environment. Surface and bulk properties, which determine the adhesion, friction, and wear behaviors of solid-solid couples, are described. The primary emphasis is on the nature and character of the metal, especially its surface energy and ductility. Also, the mechanisms of friction and wear for clean, smooth surfaces are stated.

  17. Laser treatment of white China surface

    NASA Astrophysics Data System (ADS)

    Osvay, K.; Képíró, I.; Berkesi, O.

    2006-04-01

    The surface of gloss fired porcelain with and without raw glaze coating was radiated by a CO 2 laser working at 10.6 μm, a choice resulted from spectroscopic studies of suspensions made of China. The shine of the untreated sample was defined as the distribution of micro-droplets on the surface. The surface alterations due to laser heating were classified by the diameter of the completely melted surface, the ring of the surface at the threshold of melting, and the size of microscopic cracks. The diameter of the laser treated area was in the range of 3 mm, while the incident laser power and the duration of laser heating were varied between 1 and 10 W and 1-8 min, respectively. The different stages of surface modifications were attributed primarily to the irradiating laser power and proved to be rather insensitive to the duration of the treatment. We have found a range of parameters under which the white China surface coated with raw glaze and followed by laser induced melting exhibited very similar characteristics to the untreated porcelain. This technique seems prosperous for laser assisted reparation of small surface defects of unique China samples after the firing process.

  18. Cleaning Efficiencies of Three Cleaning Agents on Four Different Surfaces after Contamination by Gemcitabine and 5-fluorouracile.

    PubMed

    Böhlandt, Antje; Groeneveld, Svenja; Fischer, Elke; Schierl, Rudolf

    2015-01-01

    Occupational exposure to antineoplastic drugs has been documented for decades showing widespread contamination in preparation and administration areas. Apart from preventive measures, efficient cleaning of surfaces is indispensable to minimize the exposure risk. The aim of this study was to evaluate the efficiency of three cleaning agents after intentional contamination by gemcitabine (GEM) and 5-fluorouracile (5-FU) on four different surface types usually installed in healthcare settings. Glass, stainless steel, polyvinylchloride (PVC), and laminated wood plates were contaminated with 20 ng/μl GEM and 2 ng/μl 5-FU solutions. Wipe samples were analyzed for drug residues after cleaning with a) distilled water, b) aqueous solution containing sodium dodecyl sulfate (10 mM) and 2-propanol (SDS-2P), and c) Incides N (pre-soaked) alcoholic wipes. Quantification was performed by high-performance liquid chromatography (HPLC) for GEM and gas chromato-graphy-tandem mass spectrometry (GCMS/MS) for 5-FU. Recovery was determined and cleaning efficiency was calculated for each scenario. Mean recoveries were 77-89% for GEM and 24-77% for 5-FU and calculated cleaning efficiencies ranged between 95 and 100% and 89 and 100%, respectively. Residual drug amounts were detected in the range nd (not detected) - 84 ng GEM/sample and nd - 6.6 ng 5-FU/sample depending on surface type and cleaning agent. Distilled water and SDS-2P had better decontamination outcomes than Incides N wipes on nearly all surface types, especially for GEM. Regarding 5-FU, the overall cleaning efficiency was lower with highest residues on laminated wood surfaces. The tested cleaning procedures are shown to clean glass, stainless steel, PVC, and laminated wood with an efficiency of 89-100% after contamination with GEM and 5-FU. Nevertheless, drug residues could be verified by wipe samples. Pure distilled water and SDS in an alcoholic-aqueous solution expressed an efficient cleaning performance, especially with

  19. EWOD driven cleaning of bioparticles on hydrophobic and superhydrophobic surfaces.

    PubMed

    Jönsson-Niedziółka, M; Lapierre, F; Coffinier, Y; Parry, S J; Zoueshtiagh, F; Foat, T; Thomy, V; Boukherroub, R

    2011-02-01

    Environmental air monitoring is of great interest due to the large number of people concerned and exposed to different possible risks. From the most common particles in our environment (e.g. by-products of combustion or pollens) to more specific and dangerous agents (e.g. pathogenic micro-organisms), there are a large range of particles that need to be controlled. In this article we propose an original study on the collection of electrostatically deposited particles using electrowetting droplet displacement. A variety of particles were studied, from synthetic particles (e.g. Polystyrene Latex (PSL) microsphere) to different classes of biological particle (proteins, bacterial spores and a viral simulant). Furthermore, we have compared ElectroWetting-On-Dielectric (EWOD) collecting efficiency using either a hydrophobic or a superhydrophobic counter electrode. We observe different cleaning efficiencies, depending on the hydrophobicity of the substrate (varying from 45% to 99%). Superhydrophobic surfaces show the best cleaning efficiency with water droplets for all investigated particles (MS2 bacteriophage, BG (Bacillus atrophaeus) spores, OA (ovalbumin) proteins, and PSL).

  20. EWOD driven cleaning of bioparticles on hydrophobic and superhydrophobic surfaces.

    PubMed

    Jönsson-Niedziółka, M; Lapierre, F; Coffinier, Y; Parry, S J; Zoueshtiagh, F; Foat, T; Thomy, V; Boukherroub, R

    2011-02-01

    Environmental air monitoring is of great interest due to the large number of people concerned and exposed to different possible risks. From the most common particles in our environment (e.g. by-products of combustion or pollens) to more specific and dangerous agents (e.g. pathogenic micro-organisms), there are a large range of particles that need to be controlled. In this article we propose an original study on the collection of electrostatically deposited particles using electrowetting droplet displacement. A variety of particles were studied, from synthetic particles (e.g. Polystyrene Latex (PSL) microsphere) to different classes of biological particle (proteins, bacterial spores and a viral simulant). Furthermore, we have compared ElectroWetting-On-Dielectric (EWOD) collecting efficiency using either a hydrophobic or a superhydrophobic counter electrode. We observe different cleaning efficiencies, depending on the hydrophobicity of the substrate (varying from 45% to 99%). Superhydrophobic surfaces show the best cleaning efficiency with water droplets for all investigated particles (MS2 bacteriophage, BG (Bacillus atrophaeus) spores, OA (ovalbumin) proteins, and PSL). PMID:21103534

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

  2. Atmospheric-Pressure Plasma Cleaning of Contaminated Surfaces

    SciTech Connect

    Robert F. Hicks; Hans W. Herrmann

    2003-12-15

    The purpose of this project was to demonstrate a practical, environmentally benigh technology for the surface decontamination and decommissioning of radioactive waste. A low temperature, atmospheric pressure plasma has been developed with initial support from the DOE, Environmental Management Sciences Program. This devise selectively etches radioactive metals from surfaces, rendering objects radiation free and suitable for decommissioning. The volatile reaction products are captured on filters, which yields a tremendous reduction in the volume of the waste. The technology shows a great potential for accelerating the clean-up effort for the equipment and structures contaminated with radioactive materials within the DOE complex. The viability of this technology has been demonstrated by selectively and rapidly stripping uranium from stainless steel surfaces at low temperature. Studies on uranium oxide have shown that etch rates of 4.0 microns per minute can be achieved at temperature below 473 K. Over the past three years, we have made numerous improvements in the design of the atmospheric pressure plasma source. We are now able to scale up the plasma source to treat large surface areas.

  3. Method for in-situ cleaning of carbon contaminated surfaces

    DOEpatents

    Klebanoff, Leonard E.; Grunow, Philip; Graham, Jr., Samuel

    2006-12-12

    Activated gaseous species generated adjacent a carbon contaminated surface affords in-situ cleaning. A device for removing carbon contamination from a surface of the substrate includes (a) a housing defining a vacuum chamber in which the substrate is located; (b) a source of gaseous species; and (c) a source of electrons that are emitted to activate the gaseous species into activated gaseous species. The source of electrons preferably includes (i) a filament made of a material that generates thermionic electron emissions; (ii) a source of energy that is connected to the filament; and (iii) an electrode to which the emitted electrons are attracted. The device is particularly suited for photolithography systems with optic surfaces, e.g., mirrors, that are otherwise inaccessible unless the system is dismantled. A method of removing carbon contaminants from a substrate surface that is housed within a vacuum chamber is also disclosed. The method employs activated gaseous species that react with the carbon contaminants to form carbon containing gaseous byproducts.

  4. Laser decontamination of epoxy painted concrete surfaces in nuclear plants

    NASA Astrophysics Data System (ADS)

    Anthofer, A.; Lippmann, W.; Hurtado, A.

    2014-04-01

    Laser technology offers an efficient decontamination of surfaces contaminated by polychlorinated biphenyls (PCB) by precise application of highly focused laser beam power. In the context of nuclear decommissioning all walls and floors of a reactor building have to be cleaned from chemical-toxic substances. State of the art is a manual and mechanic ablation and a subsequent treatment in a hazardous waste incinerator. In this study, alternatively, a laser-based system exhibiting, decontamination rates of up to 6.4 m2/h has been operated using a 10 kW diode laser in continuous wave (CW) mode with a spot size of 45×10 mm2 and a wavelength of 980-1030 nm. The system allows a rapid heating of the surfaces up to temperatures of more than 1000 °C leading to ablation and thermal decomposition of PCB in one process step. Thermal quenching prevents formation of polychlorinated dioxines (PCDD) and polychlorinate furans (PCDF) in the flue gas. Additionally, an in situ measurement system based on laser induced fluorescence (LIF) is developed to monitor the thermal decomposition of PCB. For initial experiments samples covered with epoxy paint were used to evaluate the process and to carry out finite element based simulations. In this paper, experimental results of ablation tests by laser irradiation of epoxy painted concrete are presented and discussed.

  5. Laser Surface Preparation for Adhesive Bonding of Ti-6Al-4V

    NASA Technical Reports Server (NTRS)

    Belcher, Marcus A.; List, Martina S.; Wohl, Christopher J.; Ghose, Sayata; Watson, Kent A.; Hopkins, John W.; Connell, John W.

    2010-01-01

    Adhesively bonded structures are potentially lighter in weight than mechanically fastened ones, but existing surface treatments are often considered unreliable. Two main problems in achieving reproducible and durable adhesive bonds are surface contamination and variability in standard surface preparation techniques. In this work three surface pretreatments were compared: laser etching with and without grit blasting and conventional Pasa-Jell treatment. Ti-6Al-4V surfaces were characterized by contact angle goniometry, optical microscopy, and X-ray photoelectron spectroscopy (XPS). Laser -etching was found to produce clean surfaces with precisely controlled surface topographies and PETI-5 lap shear strengths and durabilities were equivalent to those produced with Pasa-Jell.

  6. Surface Structure and Surface Electronic States Related to Plasma Cleaning of Silicon and Germanium

    NASA Astrophysics Data System (ADS)

    Cho, Jaewon

    This thesis discusses the surface structure and the surface electronic states of Si and Ge(100) surfaces as well as the effects of oxidation process on the silicon oxide/Si(100) interface structure. The H-plasma exposure was performed in situ at low temperatures. The active species, produced in the H-plasma by the rf-excitation of H_2 gas, not only remove microcontaminants such as oxygen and carbon from the surface, but also passivate the surface with atomic hydrogen by satisfying the dangling bonds of the surface atoms. The surfaces were characterized by Angle Resolved UV-Photoemission Spectroscopy (ARUPS) and Low Energy Electron Diffraction (LEED). In the case of Si(100), H-plasma exposure produced ordered H-terminated crystallographic structures with either a 2 x 1 or 1 x 1 LEED pattern. The hydride phases, found on the surfaces of the cleaned Si(100), were shown to depend on the temperature of the surface during H-plasma cleaning. The electronic states for the monohydride and dihydride phases were identified by ARUPS. When the plasma cleaned surface was annealed, the phase transition from the dihydride to monohydride was observed. The monohydride Si-H surface bond was stable up to 460^circC, and the dangling bond surface states were identified after annealing at 500^circC which was accompanied by the spectral shift. The H-terminated surface were characterized to have a flat band structure. For the Ge(100) surface, an ordered 2 x 1 monohydride phase was obtained from the surface cleaned at 180 ^circC. After plasma exposure at <=170^circC a 1 x 1 surface was observed, but the ARUPS indicated that the surface was predominantly composed of disordered monohydride structures. After annealing above the H-dissociation temperatures, the shift in the spectrum was shown to occur with the dangling bond surface states. The H-terminated surfaces were identified to be unpinned. The interface structure of silicon oxide/Si(100) was studied using ARUPS. Spectral shifts were

  7. LEEM investigations of clean surfaces driven by energetic ion beams

    SciTech Connect

    Abbamonte, Peter M.

    2013-04-24

    The original purpose of this award was to use low‐energy electron microscopy (LEEM) to explore the dynamics of surfaces of clean single crystal surfaces when driven by a beam of energetic ions. The goal was to understand the nanoscience of hyperthermal growth, surface erosion by sublimation and irradiation, operation of surface sinks in irradiated materials, diffusion on driven surfaces, and the creation of structural patterns. This project was based on a novel LEEM system constructed by C. P. Flynn, which provided real‐time imaging of surface dynamics by scattering low energy electrons. With the passing of Prof. Flynn in late 2011, this project was completed under a slightly different scope by constructing a low‐energy, inelastic electron scattering (EELS) instrument. Consistent with Flynn's original objectives for his LEEM system, this device probes the dynamics of crystal surfaces. However the measurements are not carried out in real time, but instead are done in the frequency domain, through the energy lost from the probe electrons. The purpose of this device is to study the collective bosonic excitations in a variety of materials, including high temperature superconductors, topological insulators, carbon allotropes including (but not limited to) graphene, etc. The ultimate goal here is to identify the bosons that mediate interactions in these and other materials, with hopes of shedding light on the origin of many exotic phenomena including high temperature superconductivity. We completed the construction of a low‐energy EELS system that operates with an electron kinetic energy of 7 - 10 eV. With this instrument now running, we hope to identify, among other things, the bosons that mediate pairing in high temperature superconductors. Using this instrument, we have already made our first discovery. Studying freshly cleaved single crystals of Bi{sub 2}Se{sub 3}, which is a topological insulator, we have observed a surface excitation at an energy loss of

  8. Cleaning of optical components for high-power laser-based firing systems

    SciTech Connect

    Sparrow, B.D.; Hendrix, J.L.

    1993-08-01

    This report discusses the progress of AlliedSignal Inc., Kansas City Division (KCD), in addressing the issues of cleaning of hardware and optical components for laser-based firing sets. These issues are acceptability of cleaning processes and techniques of other government programs to the quality, reliability, performance, stockpile life, materials compatibility issues, and, perhaps most important, environmentally conscious manufacturing requirements of the Department of Energy (DOE). A review of ``previous cleaning art`` is presented using Military Standards (MIL STDs) and Military Interim Specifications (MISs) as well as empirical data compiled by the authors. Observations on processes and techniques used in building prototype hardware and plans for future work are presented.

  9. SAGE SOLVENT ALTERNATIVES GUIDE: SYSTEM IMPROVEMENTS FOR SELECTING INDUSTRIAL SURFACE CLEANING ALTERNATIVES

    EPA Science Inventory

    The paper describes computer software, called SAGE, that can provide not only cleaning recommendations but also general information on various surface cleaning options. In short, it is an advisory system which can provide users with vital information on the cleaning process optio...

  10. Photoinduced laser etching of a diamond surface

    SciTech Connect

    Kononenko, V V; Komlenok, M S; Pimenov, S M; Konov, V I

    2007-11-30

    Nongraphitising ablation of the surface of a natural diamond single crystal irradiated by nanosecond UV laser pulses is studied experimentally. For laser fluences below the diamond graphitisation threshold, extremely low diamond etching rates (less than 1nm/1000 pulses) are obtained and the term nanoablation is used just for this process. The dependence of the nanoablation rate on the laser fluence is studied for samples irradiated both in air and in oxygen-free atmosphere. The effect of external heating on the nanoablation rate is analysed and a photochemical mechanism is proposed for describing it. (interaction of laser radiation with matter. laser plasma)

  11. Simultaneous UV-IR Nd:YAG Laser Cleaning of Leather Artifacts

    NASA Astrophysics Data System (ADS)

    Batishche, S.; Kouzmouk, A.; Tatur, H.; Gorovets, T.; Pilipenka, U.; Ukhau, V.; Kautek, Wolfgang

    Ancient leather samples from original upholstered furniture were treated with nanosecond Nd:YAG laser radiation with wavelengths of 1,064, 532, and 266 nm. The novel approach was the simultaneous application of these wavelengths. It opened new approaches for laser cleaning leather. Extensive diagnostics such as absorbance of different layers of leather, chemical composition and microscopic inspection studies before and after cleaning were conducted. Advantageous results with simultaneous UV-IR (266nm + 1,064nm) radiation are presented and discussed.

  12. Ultraviolet laser treatment of titanium surface

    NASA Astrophysics Data System (ADS)

    Balchev, Ivaylo; Minkovski, Nikolai; Dimitrov, Krasimir; Shipochka, Maria; Barbucha, Robert

    2016-02-01

    Interaction of a third harmonic of DPSS laser, wavelength 355 nm and pulse duration of 30 ns with titanium wafers was studied. It was investigated the structure of laser ablated titanium surface, depending on the laser beam scanning speed, and laser pulse frequency. The titanium surface modification was studied by scanning electron microscopy (SEM) and XPS (X- ray Photoelectron Spectroscopy). Nanosecond irradiation with ultraviolet light of Ti plate led to the formation of high porous granular structures consisting of agglomerated micro- and submicro- particles.

  13. Laser-assisted photoemission from surfaces

    SciTech Connect

    Saathoff, G.; Miaja-Avila, L.; Murnane, M. M.; Kapteyn, H. C.; Aeschlimann, M.

    2008-02-15

    We investigate the laser-assisted photoelectric effect from a solid surface. By illuminating a Pt(111) sample simultaneously with ultrashort 1.6 and 42 eV pulses, we observe sidebands in the extreme ultraviolet photoemission spectrum, and accurately extract their amplitudes over a wide range of laser intensities. Our results agree with a simple model, in which soft x-ray photoemission is accompanied by the interaction of the photoemitted electron with the laser field. This strong effect can definitively be distinguished from other laser surface interaction phenomena, such as hot electron excitation, above-threshold photoemission, and space-charge acceleration. Thus, laser-assisted photoemission from surfaces promises to extend pulse duration measurements to higher photon energies, as well as opening up measurements of femtosecond-to-attosecond electron dynamics in solid and surface-adsorbate systems.

  14. Surface cleaning of CCD imagers using an electrostatic dissipative formulation of First Contact polymer

    NASA Astrophysics Data System (ADS)

    Derylo, G.; Estrada, J.; Flaugher, B.; Hamilton, J.; Kubik, D.; Kuk, K.; Scarpine, V.

    2008-07-01

    We describe the results obtained cleaning the surface of DECam CCD detectors with a new electrostatic dissipative formulation of First ContactTM polymer from Photonic Cleaning Technologies. We demonstrate that cleaning with this new product is possible without ESD damage to the sensors and without degradation of the antireflective coating used to optimize the optical performance of the detector. We show that First ContactTM is more effective for cleaning a CCD than the commonly used acetone swab.

  15. Temporal pulse cleaning by a self-diffraction process for ultrashort laser pulses

    NASA Astrophysics Data System (ADS)

    Xie, Na; Zhou, Kainan; Sun, Li; Wang, Xiaodong; Guo, Yi; Li, Qing; Su, Jingqin

    2014-11-01

    Applying the self-diffraction process to clean ultrashort laser pulses temporally is a recently developed effective way to temporal contrast enhancement. In this paper, we attempt to clean ultrashort laser pulses temporally by the self-diffraction process. Experiments were carried out to study the temporal contrast improvement in the front-end system of an ultraintense and ultrashort laser facility, i.e. the super intense laser for experiment on the extremes (SILEX-I). The results show that the maximum conversion efficiency of the first-order self-diffraction (SD1) pulse is 11%. The temporal contrast of the SD1 signal is improved by two orders of magnitude, i.e. to 103, for a 2.4-ns prepulse with initial contrast of ~10. For a 5.5 -ns prepulse with initial contrast of 2×103, the temporal contrast of the SD1 signal is improved by more than three orders of magnitude.

  16. Improved cleaning of hydrophilic protein-coated surfaces using the combination of Nanobubbles and SDS.

    PubMed

    Liu, Guangming; Craig, Vincent S J

    2009-02-01

    The use of nanobubbles, the common surfactant sodium dodecyl sulfate (SDS), and nanobubbles in combination with SDS as cleaning agents to remove lysozyme from the solid-liquid interface has been investigated using a quartz crystal microbalance on both hydrophobic and hydrophilic surfaces. On the hydrophobic surface, significant amounts of protein remained on the surface after 10 cycles of nanobubble treatment for 10 s periods in phosphate buffer. The cleaning efficiency of SDS was far superior and was shown to remove approximately 90% of the protein. The use of nanobubbles in combination with SDS failed to improve the cleaning efficiency further. On the other hand, lysozyme on the hydrophilic surface cannot be removed effectively by either 10 cycles of cleaning with nanobubbles or 10 cycles of cleaning with SDS. Nevertheless, the protein can be removed completely after 6 cycles of cleaning with nanobubbles in combination with SDS.

  17. Marker and pen graffiti cleaning on diverse calcareous stones by different laser techniques

    NASA Astrophysics Data System (ADS)

    Andriani, S. E.; Catalano, I. M.; Daurelio, G.; Albanese, A.

    2007-05-01

    Industries nowadays continuously produce new types of inks for markers and pens, so new different graffiti appear . In this paper laser cleaning tests on 41 new marker and pen types ( fluorescent, permanent, water-based, acrylic tempera, metallic paint, waterproof inks ), applied into laboratory on different litho- type samples (Chianca, Travertino di Roma, Tufo Carparo fine grain, Sabbie), typical stones employed in much more monuments in Puglia and Italian architectures were carried out. The same ones, were exposed for twelve months to outdoor ageing, subject to sunshine, rain, wind, IR and UV solar radiations. Ablation experiments and tests by using different cleaning techniques, each one in Dry and Wet condition (classic technique, Daurelio technique 1 and Daurelio technique 2 and others new techniques) and two different Nd:YAG laser systems (Palladio by QUANTA SYSTEM and SMART CLEAN II by EL.EN.), were adopted. The experimental modes, N-Mode (1064nm - 150, 300 and 500 μs pulse duration), Q-Switch (1064nm - 8 ns pulse duration) and SFR (Short Free Running - 1064 nm - 40 to 110μs pulse duration) were tested on each marked stones. It was found that according to the different ink types and stone substrate, Q-Switch laser cleaning ablation with optimized laser technique are the best solution to marker an pen graffiti removal. The work is still in progress.

  18. Morphometric analysis of root canal cleaning after rotary instrumentation with or without laser irradiation

    NASA Astrophysics Data System (ADS)

    Marchesan, Melissa A.; Geurisoli, Danilo M. Z.; Brugnera, Aldo, Jr.; Barbin, Eduardo L.; Pecora, Jesus D.

    2002-06-01

    The present study examined root canal cleaning, using the optic microscope, after rotary instrumentation with ProFile.04 with or without laser application with different output energies. Cleaning and shaping can be accomplished manually, with ultra-sonic and sub-sonic devices, with rotary instruments and recently, increasing development in laser radiation has shown promising results for disinfection and smear layer removal. In this study, 30 palatal maxillary molar roots were examined using an optic microscope after rotary instrumentation with ProFile .04 with or without Er:YAG laser application (KaVo KeyLaser II, Germany) with different output energies (2940 nm, 15 Hz, 300 pulses, 500 milli-sec duration, 42 J, 140 mJ showed on the display- input, 61 mJ at fiberoptic tip-output and 140 mJ showed on the display-input and 51 mJ at fiberoptic tip-output). Statistical analysis showed no statistical differences between the tested treatments (ANOVA, p>0.05). ANOVA also showed a statistically significant difference (p<0.01) between the root canal thirds, indicating that the middle third had less debris than the apical third. We conclude that: 1) none of the tested treatments led to totally cleaned root canals; 2) all treatments removed debris similarly, 3) the middle third had less debris than the apical third; 4) variation in output energy did not increase cleaning.

  19. Self-cleaning of superhydrophobic surfaces by spontaneously jumping condensate drops

    NASA Astrophysics Data System (ADS)

    Wisdom, Katrina; Watson, Jolanta; Watson, Gregory; Chen, Chuan-Hua

    2012-11-01

    The self-cleaning function of superhydrophobic surfaces is conventionally attributed to the removal of contaminating particles by impacting or rolling water droplets, which implies the action of external forces such as gravity. Here, we demonstrate a new self-cleaning mechanism, whereby condensate drops spontaneously jump upon coalescence on a superhydrophobic surface, and the merged drop self-propels away from the surface along with the contaminants. The jumping-condensate mechanism is shown to autonomously clean superhydrophobic cicada wings, where the contaminating particles cannot be removed by external wind flow. Our findings offer new insights for the development of self-cleaning materials.

  20. Laser Surface Preparation for Adhesive Bonding of Aerospace Structural Composites

    NASA Technical Reports Server (NTRS)

    Belcher, M. A.; Wohl, C. J.; Hopkins, J. W.; Connell, J. W.

    2010-01-01

    Adhesive bonds are critical to the integrity of built-up structures. Disbonds can often be detected but the strength of adhesion between surfaces in contact is not obtainable without destructive testing. Typically the number one problem in a bonded structure is surface contamination, and by extension, surface preparation. Standard surface preparation techniques, including grit blasting, manual abrasion, and peel ply, are not ideal because of variations in their application. Etching of carbon fiber reinforced plastic (CFRP) panels using a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser appears to be a highly precise and promising way to both clean a composite surface prior to bonding and provide a bond-promoting patterned surface akin to peel ply without the inherent drawbacks from the same (i.e., debris and curvature). CFRP surfaces prepared using laser patterns conducive to adhesive bonding were compared to typical pre-bonding surface treatments through optical microscopy, contact angle goniometry, and post-bonding mechanical testing.

  1. Innovative Laser Ablation Technology for Surface Decontamination

    SciTech Connect

    Chen, Winston C. H.

    2003-06-01

    The objective of this project is to develop a novel laser ablation in liquid for surface decontamination. It aims to achieve more efficient surface decontamination without secondary contamination. Another aim is to make this surface decontamination technology becomes economically feasible for large scale decontamination.

  2. Laser ablation cleaning of an underwater archaeological bronze spectacle plate from the H.M.S. DeBraak shipwreck

    NASA Astrophysics Data System (ADS)

    Dajnowski, Bartosz A.

    2013-05-01

    Laser ablation was successfully used to sequentially remove layers of concretion and corrosion from the surface of a copper alloy spectacle plate from the shipwreck of His Majesty's Sloop of War DeBraak. The H.M.S. DeBraak was a single-masted cutter that was originally a Dutch ship until it was taken by the British, refitted, and repurposed as a Royal Navy ship in 1796. The ship sank along the Delaware coast in 1798 and artifacts were recovered from the wreck site in 1984. This spectacle plate is an important part of the ships rudder and it is part of the collection of the Delaware Division of Historical and Cultural Affairs. The object was brought the Winterthur/University of Delaware Program in Art Conservation for treatment. The object was examined with cross section microscopy, Raman spectroscopy, X-ray fluorescence spectroscopy (XRF), and Energy Dispersive Spectroscopy (EDS) as well as Back Scattered Electron (BSE) analysis with a Scanning Electron Microscopy (SEM). Interestingly, layers of both copper and iron corrosion products were identified within the concretion. A 1064nm Long Q-Switch (LQS) laser with 100ns pulses was tested along with a Short Free Running (SFR) with 60 - 130 microseconds pulses, at various fluences and frequencies, to determine optimal cleaning parameters for removing the concretion. Laser cleaning also revealed fragments of wood from the original rudder, which were previously trapped within the concretion. After laser cleaning, the spectacle plate was treated with 3% Benzotriazole in ethanol and then given a protective microcrystalline wax coating.

  3. Multiperiod-grating surface-emitting lasers

    NASA Technical Reports Server (NTRS)

    Lang, Robert J. (Inventor)

    1992-01-01

    Surface-emitting distributed feedback (DFB) lasers are disclosed with hybrid gratings. A first-order grating is provided at one or both ends of the active region of the laser for retroreflection of light back into the active region, and a second-order or nonresonant grating is provided at the opposite end for coupling light out perpendicular to the surfaces of the laser or in some other selected direction. The gratings may be curved to focus light retroreflected into the active region and to focus light coupled out to a point. When so focused to a point, the DFB laser may be part of a monolithic read head for a laser recorded disk, or an optical coupler into an optical fiber.

  4. Visible light surface emitting semiconductor laser

    DOEpatents

    Olbright, Gregory R.; Jewell, Jack L.

    1993-01-01

    A vertical-cavity surface-emitting laser is disclosed comprising a laser cavity sandwiched between two distributed Bragg reflectors. The laser cavity comprises a pair of spacer layers surrounding one or more active, optically emitting quantum-well layers having a bandgap in the visible which serve as the active optically emitting material of the device. The thickness of the laser cavity is m .lambda./2n.sub.eff where m is an integer, .lambda. is the free-space wavelength of the laser radiation and n.sub.eff is the effective index of refraction of the cavity. Electrical pumping of the laser is achieved by heavily doping the bottom mirror and substrate to one conductivity-type and heavily doping regions of the upper mirror with the opposite conductivity type to form a diode structure and applying a suitable voltage to the diode structure. Specific embodiments of the invention for generating red, green, and blue radiation are described.

  5. Cleaning and passivation of copper surfaces to remove surface radioactivity and prevent oxide formation

    SciTech Connect

    Hoppe, Eric W.; Seifert, Allen; Aalseth, Craig E.; Bachelor, Paula P.; Day, Anthony R.; Edwards, Danny J.; Hossbach, Todd W.; Litke, Kevin E.; McIntyre, Justin I.; Miley, Harry S.; Schulte, Shannon M.; Smart, John E.; Warren, Glen A.

    2007-08-21

    High-purity copper is an attractive material for constructing ultra-low-background radiation measurement devices. Many low-background experiments using high-purity copper have indicated surface contamination emerges as the dominant background. Radon daughters plate out on exposed surfaces, leaving a residual 210Pb background that is difficult to avoid. Dust is also a problem; even under cleanroom conditions, the amount of U and Th deposited on surfaces can represent the largest remaining background. To control these backgrounds, a copper cleaning chemistry has been developed. Designed to replace an effective, but overly aggressive concentrated nitric acid etch, this peroxide-based solution allows for a more controlled cleaning of surfaces. The acidified hydrogen peroxide solution will generally target the Cu+/Cu2+ species which are the predominant surface participants, leaving the bulk of copper metal intact. This preserves the critical tolerances of parts and eliminates significant waste disposal issues. Accompanying passivation chemistry has also been developed that protects copper surfaces from oxidation. Using a high-activity polonium surface spike, the most difficult-to-remove daughter isotope of radon, the performance of these methods are quantified. © 2001 Elsevier Science. All rights reserved

  6. Laser surface processing on sintered PM alloys

    NASA Astrophysics Data System (ADS)

    Reiter, Wilfred; Daurelio, Giuseppe; Ludovico, Antonio D.

    1997-08-01

    Usually the P.M. alloys are heat treated like case hardening, gas nitriding or plasma nitriding for a better wear resistance of the product surface. There is an additional method for gaining better tribological properties and this is the surface hardening (or remelting or alloying) of the P.M. alloy by laser treatment on a localized part of the product without heating the whole sample. This work gives a cured experimentation about the proper sintering powder alloys for laser surface processing from the point of view of wear, fatigue life and surface quality. As concerns the materials three different basic alloy groups with graduated carbon contents were prepared. Regarding these sintered powder alloys one group holds Fe, Mo and C and other group holds Fe, Ni, Mo and C and the last one holds Fe, Ni, Cu, Mo and C contents. Obviously each group has a different surface hardness, different porosity distribution, different density and diverse metallurgical structures (pearlite or ferrite-pearlite, etc.). ON the sample surfaces a colloidal graphite coating, in different thicknesses, has been sprayed to increase laser energy surface absorption. On some other samples a Mo coating, in different thicknesses, has been produced (on the bulk alloy) by diverse deposition techniques (D.C. Sputtering, P.V.D. and Flame Spraying). Only a few samples have a Mo coating and also an absorber coating, that is a bulk material- Mo and a colloidal graphite coating. All these sintered alloys have been tested by laser technology; so that, many laser working parameters (covering gas, work-speed, focussed and defocussed spot, rastered and integrated beam spots, square and rectangular beam shapes and so on) have been experimented for two different processes at constant laser power and at constant surface temperature (by using a temperature surface sensor and a closed controlled link). For all experiments a transverse fast axial flow CO2 2.5 kW c.w. laser source has been employed.

  7. IBA analysis of a laser cleaned archaeological metal object: The San Esteban de Gormaz cross (Soria-Spain)

    NASA Astrophysics Data System (ADS)

    Zucchiatti, A.; Gutiérrez Neira, P. C.; Climent-Font, A.; Escudero, C.; Barrera, M.

    2011-12-01

    The object under study, a 12th century gilded copper cross with a wooden core, now almost disappeared, shows the typical features produced by a long burial time: the entire surface of the copper alloys is covered by several layers of degradation products, which hinder the "legibility" of the cross in terms of the original materials and manufacturing techniques employed. In its cleaning several techniques have been applied and compared (dry and wet laser ablation, mechanical ablation, ultrasound brush). In the intermediate cleaning phase the cross has been extensively analysed with the external proton micro-beam of the Centro de Micro-Análisis de Materiales (CMAM) of the Universidad Autónoma de Madrid. PIXE and RBS techniques have been used in parallel, to asses both the chemical composition and the layered structure of cleaned and original parts with the aim of verifying that none of the object structural features are being modified by the cleaning process leaving intact the possibility of artistic interpretation of the object (e.g. small series production of the cross elements). The recovery of this exceptional ornamental object is made possible by the coordinated work of several professionals coming from various disciplines and aimed at establishing the importance of this cross in terms of its physical appearance and in terms of the manufacturing techniques.

  8. Composition control in laser surface alloying

    NASA Astrophysics Data System (ADS)

    Chande, T.; Mazumder, J.

    1983-06-01

    Laser surface alloying, a process of growing interest for local surface modification, relies upon a suitable composition and microstructure for satisfactory on-the-job performance. This paper reports the results of an initial systematic study of laser surface alloying nickel onto AISI 1020 steel substrates using a statistical experimental design technique. The objective was to relate processing conditions to dimensions, solute content, and microstructural refinement of the laser alloyed zones. Solute content was of principal concern as it is the single most important factor affecting the properties of laser surface alloys. The effects of varying the laser power, beam diameter, and speed on the width, depth, nickel content, and fluctuations in nickel content are reported. Interactions between process parameters are discussed, the reproducibility assessed, contour plots for solute content drawn. Dimensionless plots are developed that relate average solute content and microstructural refinement to process parameters. Previously published data for alloying chromium into 1018 steels are shown to contain similar trends. It is felt that such an approach would facilitate selection of processing conditions to obtain reproducibly the compositions and microstructures necessary for gainful utilization of laser surface alloys.

  9. Laser cleaning of the interior stone decoration of King Sigismund's Chapel at Wawel Castle in Cracow

    NASA Astrophysics Data System (ADS)

    Marczak, Jan; Strzelec, Marek; Koss, Andrzej

    2005-09-01

    The paper presents a part of the results of EUREKA E!2542 RENOVA LASER project "Laser renovation of monuments and works of art", realized in the years 2001-2004, aimed to the application of laser technique to the conservation of artworks and historic objects in architectural scale. Laser technology has been blended into the full program of conservation and restoration of Sigismund's Chapel at Wawel Castle in Cracow, Poland, including more than 800 m2 of decorative, XVI century sculptor's surfaces.

  10. Effect of defocusing distance on the contaminated surface of brass ring with nanosecond laser in a 3D laser scanning system

    NASA Astrophysics Data System (ADS)

    Zhao, Mali; Liu, Tiegen; Jiang, Junfeng; Wang, Meng

    2014-08-01

    Defocusing distance plays a key role in laser cleaning result and can be either positive or negative, depending on the focus position relative to the sample surface. In this paper, we investigate the effect of the defocusing distance on the cleaning efficiency of oxidized brass surface. The oxide layer from the surface of a brass ring was processed with a three dimensional (3-D) dynamically focused laser galvanometer scanning system. The relationship between removal efficiency of the oxide layer and the defocusing distance was analyzed. The sample surface topography, element content before and after the laser cleaning were analyzed by a scanning electron microscope (SEM) and Energy-dispersive X-ray spectroscopy (EDS), the surface quality after laser cleaning was analyzed by a Atomic Force Microscope (AFM), the chemical constituents of the oxide layer on the sample surface after being processed with different defocusing distances were examined by x-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). The results show that the ratios of Cu/O and Zn/O reach the maximum of 53.2 and 27.78 respectively when the defocusing distance is +0.5 mm. The laser pulses will lose the ability to remove the oxide layer from the substrate surface when the defocusing distance is larger than ±2 mm.

  11. Vertical-Cavity Surface-Emitting Lasers

    NASA Astrophysics Data System (ADS)

    Wilmsen, Carl W.; Temkin, Henryk; Coldren, Larry A.

    2002-01-01

    1. Introduction to VCSELs L. A. Coldren, C. W. Wilmsen and H. Temkin; 2. Fundamental issues in VCSEL design L. A. Coldren and Eric R. Hegblom; 3. Enhancement of spontaneous emission in microcavities E. F. Schubert and N. E. J. Hunt; 4. Epitaxy of vertical-cavity lasers R. P. Schneider Jr and Y. H. Young; 5. Fabrication and performance of vertical-cavity surface-emitting lasers Kent D. Choquette and Kent Geib; 6. Polarization related properties of vertical cavity lasers Dmitri Kuksenkov and Henryk Temkin; 7. Visible light emitting vertical cavity lasers Robert L. Thornton; 8. Long-wavelength vertical-cavity lasers Dubrakovo I. Babic, Joachim Piprek and John E. Bowers; 9. Overview of VCSEL applications Richard C. Williamson; 10. Optical interconnection applications and required characteristics Kenichi Kasahara; 11. VCSEL-based fiber-optic data communications Kenneth Hahn and Kirk Giboney; 12. VCSEL-based smart pixels for free space optoelectronic processing C. W. Wilmsen.

  12. Removal of dust particles from metal-mirror surfaces by excimer-laser radiation

    NASA Astrophysics Data System (ADS)

    Mann, Klaus R.; Wolff-Rottke, B.; Mueller, F.

    1995-07-01

    The effect of particle desorption from Al mirror surfaces by the influence of pulsed UV laser radiation has been studied. The investigations are closely related to the demands of astronomers, who are looking for a more effective way of cleaning the Al coatings of future very large telescope mirrors. A systematic parameter study has been performed in order to determine the irradiation conditions which yield the highest dust removal efficiency (i.e. reflectivity increase) on contaminated samples, taking particularly into account laser-induced damage and degradation effects of coating and substrate. The particle removal rate increases with increasing laser fluence, being limited however by the damage threshold of the coating. Therefore, parameters influencing the damage threshold of metal coatings like wavelength, pulse width, and number of pulses have been studied in detail. Data indicate that on Al coated BK7 and Zerodur samples KrF laser radiation yields the optimum result, with cleaning efficiencies comparable to polymer film stripping. The initial reflectivity of the clean coating can nearly be reinstalled, in particular when an additional solvent film on the sample surface is applied. Hence, laser desorption seems to be a viable method of cleaning large Al mirrors for telescopes.

  13. Composite Resonator Surface Emitting Lasers

    SciTech Connect

    FISCHER,ARTHUR J.; CHOQUETTE,KENT D.; CHOW,WENG W.; ALLERMAN,ANDREW A.; GEIB,KENT M.

    2000-05-01

    The authors have developed electrically-injected coupled-resonator vertical-cavity lasers and have studied their novel properties. These monolithically grown coupled-cavity structures have been fabricated with either one active and one passive cavity or with two active cavities. All devices use a selectively oxidized current aperture in the lower cavity, while a proton implant was used in the active-active structures to confine current in the top active cavity. They have demonstrated optical modulation from active-passive devices where the modulation arises from dynamic changes in the coupling between the active and passive cavities. The laser intensity can be modulated by either forward or reverse biasing the passive cavity. They have also observed Q-switched pulses from active-passive devices with pulses as short as 150 ps. A rate equation approach is used to model the Q-switched operation yielding good agreement between the experimental and theoretical pulseshape. They have designed and demonstrated the operation of active-active devices which la.se simultaneously at both longitudinal cavity resonances. Extremely large bistable regions have also been observed in the light-current curves for active-active coupled resonator devices. This bistability can be used for high contrast switching with contrast ratios as high as 100:1. Coupled-resonator vertical-cavity lasers have shown enhanced mode selectivity which has allowed devices to lase with fundamental-mode output powers as high as 5.2 mW.

  14. Automatic Workpiece Surface Tracker For Laser Cutter

    NASA Astrophysics Data System (ADS)

    Mottier, F. M.

    1980-05-01

    Precise guidance of high energy laser beams is important in industrial laser machining to optimize the use of the available power and to assure high quality work. A crossed beam depth gauge has been designed that measures the distance to the workpiece surface with an accuracy of one part in two thousand over a range of 10 cm. The television camera based system is described along with an analysis of its performance.

  15. Laser restoring the glass surface treated with acid-based paint

    NASA Astrophysics Data System (ADS)

    Strusevich, Anastasia V.; Poltaev, Yuriy A.; Sinev, Dmitrii A.

    2013-11-01

    The modern city facilities are often being attacked by graffiti artists, and increasingly vandals leave "tags" using paints, which compound based on acids, hydrofluoric or acetic commonly. These paints not only ink the surface, but also increase the surface roughness, and such impact can not be corrected by conventional cleaning. Thus, it was requested to develop technology that would not only clean the surface, but also to restore its structure by smoothing out irregularities and roughness formed after exposure in acid. In this work we investigated the effect of restoring the surface of the glass, spoiled by acid-based paint and then treated with CO2-laser. During the experiments, it was found that it is real to create the single-step laser surface restoring technology.

  16. Laser-induced periodic annular surface structures on fused silica surface

    SciTech Connect

    Liu, Yi; Brelet, Yohann; Forestier, Benjamin; Houard, Aurelien; Yu, Linwei; Deng, Yongkai; Jiang, Hongbing

    2013-06-24

    We report on the formation of laser-induced periodic annular surface structures on fused silica irradiated with multiple femtosecond laser pulses. This surface morphology emerges after the disappearance of the conventional laser induced periodic surface structures, under successive laser pulse irradiation. It is independent of the laser polarization and universally observed for different focusing geometries. We interpret its formation in terms of the interference between the reflected laser field on the surface of the damage crater and the incident laser pulse.

  17. Excimer laser surface modification: Process and properties

    SciTech Connect

    Jervis, T.R.; Nastasi, M.; Hirvonen, J.P.

    1992-12-01

    Surface modification can improve materials for structural, tribological, and corrosion applications. Excimer laser light has been shown to provide a rapid means of modifying surfaces through heat treating, surface zone refining, and mixing. Laser pulses at modest power levels can easily melt the surfaces of many materials. Mixing within the molten layer or with the gas ambient may occur, if thermodynamically allowed, followed by rapid solidification. The high temperatures allow the system to overcome kinetic barriers found in some ion mixing experiments. Alternatively, surface zone refinement may result from repeated melting-solidification cycles. Ultraviolet laser light couples energy efficiently to the surface of metallic and ceramic materials. The nature of the modification that follows depends on the properties of the surface and substrate materials. Alloying from both gas and predeposited layer sources has been observed in metals, semiconductors, and ceramics as has surface enrichment of Cr by zone refinement of stainless steel. Rapid solidification after melting often results in the formation of nonequilibrium phases, including amorphous materials. Improved surface properties, including tribology and corrosion resistance, are observed in these materials.

  18. Self-Cleaning Surfaces: A Third-Year Undergraduate Research Project

    ERIC Educational Resources Information Center

    Haines, Ronald S.; Wu, Alex H. F.; Zhang, Hua; Coffey, Jacob; Huddle, Thomas; Lafountaine, Justin S.; Lim, Zhi-Jun; White, Eugene A.; Tuong, Nam T.; Lamb, Robert N.

    2009-01-01

    Superhydrophobic (non water-wettable) surfaces can possess the ability to self-clean (the so-called "lotus effect"). The task of devising the apparatus and method for quantifying this self-cleaning effect was offered as a project in a third-year undergraduate laboratory course. Using commonly available equipment the students devised a protocol for…

  19. In situ remote RF plasma cleaning and surface characterization after silicon dioxide/silicon RIE

    NASA Astrophysics Data System (ADS)

    Ying, Hong

    In IC fabrication, etching (patterning) technology is one of the fundamental techniques. Dry etching has replaced wet etching for patterning micron and submicron features in advanced microelectronics device fabrication. Due to the dry etching induced surface modifications and damage, post-etch cleanings are necessary and critical to device fabrication. Similarly, dry cleaning or gas phase cleaning technologies have shown promise in cleaning processes where conventional wet cleans are impractical or inadequate. The focus of this thesis is the investigation of dry surface cleaning and conditioning after reactive ion etching (RIE) of SiO2 on Si. The approach is to employ in situ remote RF H2 plasma and H2/SiH4 plasma processes for RIE induced CFx residue removal and a final H-passivation of the Si surface. The major scientific issue is to develop understanding of the plasma processes that effectively remove contaminants yet do not damage existing layers. Our investigation suggests that a remote H2 plasma process is effective in removing RIE induced CFx residue and chlorine-containing residue. With the addition of ˜0.1% of SiH4, the remote H 2/SiH4 plasma has proven to be more effective in removal of residual oxide contamination. The plasma cleaning processes have been successfully developed to be fully in situ and cluster tool compatible. The processes were optimized for surface residue and via residue removal on 150 mm interconnect patterned wafers. SEM images showed that a significant amount of surface and via residue were removed. Finally, by using the cobalt silicide formation process and the Schottky diode electrical properties as two test vehicles, we demonstrated the importance of post-RIE cleaning and evaluated the remote plasma cleaning techniques as dry surface cleaning processes.

  20. Active cleaning techniques for removing contamination from optical surfaces in space

    NASA Technical Reports Server (NTRS)

    Shannon, R. L.; Gillette, R. B.

    1973-01-01

    Research in developing an active cleaning technique for removing contaminants from optical surfaces in space is reported. In situ contamination/cleaning experiments were conducted on gold and platimum coated mirrors, which were contaminated by exposure to UV radiation in a 1,3, butadiene environment. Argon and oxygen plasma exposure cleaned the mirrors equally well. Silicone cleaning experiments were also conducted. Exposure of the contaminated mirrors to helium, oxygen, and hydrogen plasmas restored the reflectance at the shorter wavelengths and degraded it at the longer wavelengths.

  1. From the Lab to the Scaffold: Laser Cleaning of Polychromed Architectonic Elements and Sculptures

    NASA Astrophysics Data System (ADS)

    Castillejo, M.; Domingo, C.; Guerra-Librero, F.; Jadraque, M.; Martín, M.; Oujja, M.; Rebollar, E.; Torres, R.

    This work presents the results of laboratory tests aiming at the characterization of painting materials by LIB and FT-Raman spectroscopies and at identification of the best laser cleaning conditions of polychromes of Spanish Heritage: polychromes on gypsum mortar of the Church-Fortress of Santa Tecla of Cervera de la Cañada, Zaragoza, fifteenth century, and appliqué relief brocades on wooden sculptures of the Chapel of San Miguel, Cathedral of Jaca, Huesca, sixteenth century.

  2. Laser-induced gas-surface interactions

    NASA Astrophysics Data System (ADS)

    Chuang, T. J.

    Chemical reactions in homogeneous systems activated by laser radiation have been extensively investigated for more than a decade. The applications of lasers to promote gas-surface interactions have just been realized in recent years. The purpose of this paper is to examine the fundamental processes involved in laser-induced gas-surface chemical interactions. Specifically, the photon-enhanced adsorption, adsorbate-adsorbate and adsorbate-solid reactions, product formation and desorption processes are discussed in detail. The dynamic processes involved in photoexcitation of the electronic and vibrational states, the energy transfer and relaxation in competition with chemical interactions are considered. These include both single and multiple photon adsorption, and fundamental and overtone transitions in the excitation process, and inter- and intra-molecular energy transfer, and coupling with phonons, electron-hole pairs and surface plasmons in the energy relaxation process. Many current experimental and theoretical studies on the subject are reviewed and discussed with the goal of clarifying the relative importance of the surface interaction steps and relating the resulting concepts to the experimentally observed phenomena. Among the many gas-solid systems that have been investigated, there has been more extensive use of CO adsorbed on metals, and SF 6 and XeF 2 interactions with silicon as examples to illustrate the many facets of the electronically and vibrationally activated surface processes. Results on IR laser stimulated desorption of C 5H 5N and C 5D 5N molecules from various solid surfaces are also presented. It is clearly shown that rapid intermolecular energy exchange and molecule to surface energy transfer can have important effects on photodesorption cross sections and isotope selectivities. It is concluded that utilization of lasers in gas-surface studies not only can provide fundamental insight into the mechanism and dynamics involved in heterogeneous

  3. Laser Induced Aluminum Surface Breakdown Model

    NASA Technical Reports Server (NTRS)

    Chen, Yen-Sen; Liu, Jiwen; Zhang, Sijun; Wang, Ten-See (Technical Monitor)

    2002-01-01

    Laser powered propulsion systems involve complex fluid dynamics, thermodynamics and radiative transfer processes. Based on an unstructured grid, pressure-based computational aerothermodynamics; platform, several sub-models describing such underlying physics as laser ray tracing and focusing, thermal non-equilibrium, plasma radiation and air spark ignition have been developed. This proposed work shall extend the numerical platform and existing sub-models to include the aluminum wall surface Inverse Bremsstrahlung (IB) effect from which surface ablation and free-electron generation can be initiated without relying on the air spark ignition sub-model. The following tasks will be performed to accomplish the research objectives.

  4. Laser-assisted photoelectric effect from surfaces.

    PubMed

    Miaja-Avila, L; Lei, C; Aeschlimann, M; Gland, J L; Murnane, M M; Kapteyn, H C; Saathoff, G

    2006-09-15

    We report the first observation of the laser-assisted photoelectric effect from a solid surface. By illuminating a Pt(111) sample simultaneously with ultrashort 1.6 eV and 42 eV pulses, we observe sidebands in the extreme ultraviolet photoemission spectrum. The magnitude of these sidebands as a function of time delay between the laser and extreme ultraviolet pulses represents a cross-correlation measurement of the extreme ultraviolet pulse. This effect promises to be useful to extend extreme ultraviolet pulse duration measurements to higher photon energies, as well as opening up femtosecond-to-attosecond time-scale electron dynamics in solid and surface-adsorbate systems.

  5. Laser Induced Aluminum Surface Breakdown Model

    NASA Technical Reports Server (NTRS)

    Chen, Yen-Sen; Liu, Jiwen; Zhang, Sijun; Wnag, Ten-See (Technical Monitor)

    2001-01-01

    Laser powered propulsion systems involve complex fluid dynamics, thermodynamics and radiative transfer processes. Based on an unstructured grid., pressure-based computational aerothermodynamics, platform, several sub-nio"'dels describing such underlying physics as laser ray tracing and focusing, thermal non-equilibrium, plasma radiation and air spark ignition have been developed. This proposed work shall extend the numerical platform and existing sub-models to include the aluminum wall surface Inverse Bremsstrahlung (113) effect from which surface ablation and free-electron generation can be initiated without relying on the air spark ignition sub-model. The following tasks will be performed to accomplish the research objectives.

  6. 75 FR 18500 - Guidance on Improving EPA Review of Appalachian Surface Coal Mining Operations under the Clean...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-12

    ... environmental review of Appalachian surface coal mining operations under the Clean Water Act, National... AGENCY Guidance on Improving EPA Review of Appalachian Surface Coal Mining Operations under the Clean..., titled Improving EPA Review of Appalachian Surface Coal Mining Operations under the Clean Water...

  7. Process for laser machining and surface treatment

    DOEpatents

    Neil, George R.; Shinn, Michelle D.

    2004-10-26

    An improved method and apparatus increasing the accuracy and reducing the time required to machine materials, surface treat materials, and allow better control of defects such as particulates in pulsed laser deposition. The speed and quality of machining is improved by combining an ultrashort pulsed laser at high average power with a continuous wave laser. The ultrashort pulsed laser provides an initial ultrashort pulse, on the order of several hundred femtoseconds, to stimulate an electron avalanche in the target material. Coincident with the ultrashort pulse or shortly after it, a pulse from a continuous wave laser is applied to the target. The micromachining method and apparatus creates an initial ultrashort laser pulse to ignite the ablation followed by a longer laser pulse to sustain and enlarge on the ablation effect launched in the initial pulse. The pulse pairs are repeated at a high pulse repetition frequency and as often as desired to produce the desired micromachining effect. The micromachining method enables a lower threshold for ablation, provides more deterministic damage, minimizes the heat affected zone, minimizes cracking or melting, and reduces the time involved to create the desired machining effect.

  8. Self-Partitioned Droplet Array on Laser-Patterned Superhydrophilic Glass Surface for Wall-less Cell Arrays.

    PubMed

    Xu, Kerui; Wang, Xiaopu; Ford, Roseanne M; Landers, James P

    2016-03-01

    In this work, we report a novel method for the creation of superhydrophilic patterns on the surface of hydrophobically coated glass through CO2 laser cleaning. This mask-free approach requires no photolithography for the print of the features, and only a single-step surface pretreatment is needed. The laser-cleaned glass surface enables self-partitioning of liquid into droplet arrays with controllable, quantitative volumes. We further designed wall-less cell arrays for the mapping of culturing conditions and demonstrated the potential of this droplet-arraying method. PMID:26878418

  9. Laser interaction with coated collagen and cellulose fibre composites: fundamentals of laser cleaning of ancient parchment manuscripts and paper

    NASA Astrophysics Data System (ADS)

    Kautek, Wolfgang; Pentzien, Simone; Rudolph, Pascale; Krüger, Jörg; König, Eberhard

    1998-05-01

    Laser cleaning of delicate biological composite materials such as ancient parchment manuscripts from the 15th and 16th century and printed paper from the 19th century is demonstrated with an ultraviolet excimer pulsed laser at 308 nm. Laser fluence levels must stay below the ablation and destruction threshold of the parchment or paper substrate, and have to surpass the threshold of the contaminant matter. Foreign layers to be removed must exhibit a higher optical density than the artifact substrates. Synthetic carbonaceous dirt modelled by water-soluble black crayons showed a characteristically weak featureless laser-induced plasma spectroscopy spectrum near the noise limit. It turned out that laser-induced plasma spectroscopy is of limited use in monitoring halting points (or etch-stops) because it relies on the destruction not only of the laterally inhomogenously distributed contaminant but also of pigment phases on a microscopically rough parchment substrate. Laser-induced fluorescence spectroscopy, however, promises to be a valuable non-destructive testing technique for etch-stop monitoring.

  10. Self-cleaning of superhydrophobic surfaces by self-propelled jumping condensate

    PubMed Central

    Wisdom, Katrina M.; Qu, Xiaopeng; Liu, Fangjie; Watson, Gregory S.; Chen, Chuan-Hua

    2013-01-01

    The self-cleaning function of superhydrophobic surfaces is conventionally attributed to the removal of contaminating particles by impacting or rolling water droplets, which implies the action of external forces such as gravity. Here, we demonstrate a unique self-cleaning mechanism whereby the contaminated superhydrophobic surface is exposed to condensing water vapor, and the contaminants are autonomously removed by the self-propelled jumping motion of the resulting liquid condensate, which partially covers or fully encloses the contaminating particles. The jumping motion off the superhydrophobic surface is powered by the surface energy released upon coalescence of the condensed water phase around the contaminants. The jumping-condensate mechanism is shown to spontaneously clean superhydrophobic cicada wings, where the contaminating particles cannot be removed by gravity, wing vibration, or wind flow. Our findings offer insights for the development of self-cleaning materials. PMID:23630277

  11. Influence of lasing parameters on the cleaning efficacy of laser-activated irrigation with pulsed erbium lasers.

    PubMed

    Meire, Maarten A; Havelaerts, Sophie; De Moor, Roeland J

    2016-05-01

    Laser-activated irrigation (LAI) using erbium lasers is an irrigant agitation technique with great potential for improved cleaning of the root canal system, as shown in many in vitro studies. However, lasing parameters for LAI vary considerably and their influence remains unclear. Therefore, this study sought to investigate the influence of pulse energy, pulse frequency, pulse length, irradiation time and fibre tip shape, position and diameter on the cleaning efficacy of LAI. Transparent resin blocks containing standardized root canals (apical diameter of 0.4 mm, 6% taper, 15 mm long, with a coronal reservoir) were used as the test model. A standardized groove in the apical part of each canal wall was packed with stained dentin debris. The canals were filled with irrigant, which was activated by an erbium: yttrium aluminium garnet (Er:YAG) laser (2940 nm, AT Fidelis, Fotona, Ljubljana, Slovenia). In each experiment, one laser parameter was varied, while the others remained constant. In this way, the influence of pulse energy (10-40 mJ), pulse length (50-1000 μs), frequency (5-30 Hz), irradiation time (5-40 s) and fibre tip shape (flat or conical), position (pulp chamber, canal entrance, next to groove) and diameter (300-600 μm) was determined by treating 20 canals per parameter. The amount of debris remaining in the groove after each LAI procedure was scored and compared among the different treatments. The parameters significantly (P < 0.05, Kruskal-Wallis) affecting debris removal from the groove were fibre tip position, pulse length, pulse energy, irradiation time and frequency. Fibre tip shape and diameter had no significant influence on the cleaning efficacy.

  12. Effect of cleaning and sterilization on titanium implant surface properties and cellular response

    PubMed Central

    Park, Jung Hwa; Olivares-Navarrete, Rene; Baier, Robert E.; Meyer, Anne E.; Tannenbaum, Rina; Boyan, Barbara D.; Schwartz, Zvi

    2013-01-01

    Titanium (Ti) has been widely used as an implant material due to the excellent biocompatibility and corrosion resistance of its oxide surface. Biomaterials must be sterile before implantation, but the effects of sterilization on their surface properties have been less well studied. The effects of cleaning and sterilization on surface characteristics were bio-determined using contaminated and pure Ti substrata first manufactured to present two different surface structures: pretreated titanium (PT, Ra = 0.4 μm) (i.e. surfaces that were not modified by sandblasting and/or acid etching); (SLA, Ra = 3.4 μm). Previously cultured cells and associated extracellular matrix were removed from all bio-contaminated specimens by cleaning in a sonicator bath with a sequential acetone–isopropanol–ethanol–distilled water protocol. Cleaned specimens were sterilized with autoclave, gamma irradiation, oxygen plasma, or ultraviolet light. X-ray photoelectron spectroscopy (XPS), contact angle measurements, profilometry, and scanning electron microscopy were used to examine surface chemical components, hydrophilicity, roughness, and morphology, respectively. Small organic molecules present on contaminated Ti surfaces were removed with cleaning. XPS analysis confirmed that surface chemistry was altered by both cleaning and sterilization. Cleaning and sterilization affected hydrophobicity and roughness. These modified surface properties affected osteogenic differentiation of human MG63 osteoblast-like cells. Specifically, autoclaved SLA surfaces lost the characteristic increase in osteoblast differentiation seen on starting SLA surfaces, which was correlated with altered surface wettability and roughness. These data indicated that recleaned and resterilized Ti implant surfaces cannot be considered the same as the first surfaces in terms of surface properties and cell responses. Therefore, the reuse of Ti implants after resterilization may not result in the same tissue responses as

  13. Stable superhydrophobic surface with hierarchical mesh-porous structure fabricated by a femtosecond laser

    NASA Astrophysics Data System (ADS)

    Yong, Jiale; Yang, Qing; Chen, Feng; Zhang, Dongshi; Bian, Hao; Ou, Yan; Si, Jinhai; Du, Guangqing; Hou, Xun

    2013-04-01

    Inspired by the lotus leaf, a new superhydrophobic surface with hierarchical mesh-porous structure is fabricated by femtosecond laser irradiation on silicon. The fabricated surface shows a superhydrophobic character with water contact angle being found to reach up to 158∘±1∘ and sliding angle of 4∘±0.5∘. The superhydrophobicity is stable even if the PH of solution changes from 1 to 14. And the surface also exhibits excellent self-cleaning effect and bouncing behavior, implying that the adhesion of the surface is extremely low. This work will enhance further understanding of the wettability of a solid surface with special surface morphology.

  14. Hard Surface Biocontrol in Hospitals Using Microbial-Based Cleaning Products

    PubMed Central

    Vandini, Alberta; Temmerman, Robin; Frabetti, Alessia; Caselli, Elisabetta; Antonioli, Paola; Balboni, Pier Giorgio; Platano, Daniela; Branchini, Alessio; Mazzacane, Sante

    2014-01-01

    Background Healthcare-Associated Infections (HAIs) are one of the most frequent complications occurring in healthcare facilities. Contaminated environmental surfaces provide an important potential source for transmission of many healthcare-associated pathogens, thus indicating the need for new and sustainable strategies. Aim This study aims to evaluate the effect of a novel cleaning procedure based on the mechanism of biocontrol, on the presence and survival of several microorganisms responsible for HAIs (i.e. coliforms, Staphyloccus aureus, Clostridium difficile, and Candida albicans) on hard surfaces in a hospital setting. Methods The effect of microbial cleaning, containing spores of food grade Bacillus subtilis, Bacillus pumilus and Bacillus megaterium, in comparison with conventional cleaning protocols, was evaluated for 24 weeks in three independent hospitals (one in Belgium and two in Italy) and approximately 20000 microbial surface samples were collected. Results Microbial cleaning, as part of the daily cleaning protocol, resulted in a reduction of HAI-related pathogens by 50 to 89%. This effect was achieved after 3–4 weeks and the reduction in the pathogen load was stable over time. Moreover, by using microbial or conventional cleaning alternatively, we found that this effect was directly related to the new procedure, as indicated by the raise in CFU/m2 when microbial cleaning was replaced by the conventional procedure. Although many questions remain regarding the actual mechanisms involved, this study demonstrates that microbial cleaning is a more effective and sustainable alternative to chemical cleaning and non-specific disinfection in healthcare facilities. Conclusions This study indicates microbial cleaning as an effective strategy in continuously lowering the number of HAI-related microorganisms on surfaces. The first indications on the actual level of HAIs in the trial hospitals monitored on a continuous basis are very promising, and may pave the

  15. Superhydrophobic and self-cleaning bio-fiber surfaces via ATRP and subsequent postfunctionalization.

    PubMed

    Nyström, Daniel; Lindqvist, Josefina; Ostmark, Emma; Antoni, Per; Carlmark, Anna; Hult, Anders; Malmström, Eva

    2009-04-01

    Superhydrophobic and self-cleaning cellulose surfaces have been obtained via surface-confined grafting of glycidyl methacrylate using atom transfer radical polymerization combined with postmodification reactions. Both linear and branched graft-on-graft architectures were used for the postmodification reactions to obtain highly hydrophobic bio-fiber surfaces by functionalization of the grafts with either poly(dimethylsiloxane), perfluorinated chains, or alkyl chains, respectively. Postfunctionalization using alkyl chains yielded results similar to those of surfaces modified by perfluorination, in terms of superhydrophobicity, self-cleaning properties, and the stability of these properties over time. In addition, highly oleophobic surfaces have been obtained when modification with perfluorinated chains was performed. PMID:20356007

  16. Superhydrophobic and self-cleaning bio-fiber surfaces via ATRP and subsequent postfunctionalization.

    PubMed

    Nyström, Daniel; Lindqvist, Josefina; Ostmark, Emma; Antoni, Per; Carlmark, Anna; Hult, Anders; Malmström, Eva

    2009-04-01

    Superhydrophobic and self-cleaning cellulose surfaces have been obtained via surface-confined grafting of glycidyl methacrylate using atom transfer radical polymerization combined with postmodification reactions. Both linear and branched graft-on-graft architectures were used for the postmodification reactions to obtain highly hydrophobic bio-fiber surfaces by functionalization of the grafts with either poly(dimethylsiloxane), perfluorinated chains, or alkyl chains, respectively. Postfunctionalization using alkyl chains yielded results similar to those of surfaces modified by perfluorination, in terms of superhydrophobicity, self-cleaning properties, and the stability of these properties over time. In addition, highly oleophobic surfaces have been obtained when modification with perfluorinated chains was performed.

  17. Pulsed laser surface hardening of ferrous alloys.

    SciTech Connect

    Xu, Z.; Reed, C. B.; Leong, K. H.; Hunter, B. V.

    1999-09-30

    A high power pulsed Nd:YAG laser and special optics were used to produce surface hardening on 1045 steel and gray cast iron by varying the process parameters. Unlike CO{sub 2} lasers, where absorptive coatings are required, the higher absorptivity of ferrous alloys at the Nd:YAG laser wavelength eliminates the necessity of applying a coating before processing. Metallurgical analysis of the treated tracks showed that very fine and hard martensitic microstructure (1045 steel) or inhomogeneous martensite (gray cast iron) were obtained without surface melting, giving maximum hardness of HRC 61 and HRC 40 for 1045 steel and gray cast iron respectively. The corresponding maximum case depths for both alloys at the above hardness are 0.6 mm. Gray cast iron was more difficult to harden without surface melting because of its lower melting temperature and a significantly longer time-at-temperature required to diffuse carbon atoms from the graphite flakes into the austenite matrix during laser heating. The thermal distortion was characterized in term of flatness changes after surface hardening.

  18. Preparation of clean InP(100) surfaces studied by synchrotron radiation photoemission

    NASA Astrophysics Data System (ADS)

    Sun, Yun; Liu, Zhi; Machuca, Francisco; Pianetta, Piero; Spicer, William E.

    2003-01-01

    The chemical cleaning of indium phosphide (InP),(100) surfaces is studied systematically by using photoemission electron spectroscopy. In order to achieve the necessary surface sensitivity and spectral resolution, synchrotron radiation with photon energies ranging from 60 to 600 eV are used to study the indium 4d, phosphorus 2p, carbon 1s, and oxygen 1s core levels, and the valence band. Typical H2SO4:H2O2:H2O solutions used to etch GaAs(100) surfaces are applied to InP(100) surfaces. It is found that the resulting surface species are significantly different from those found on GaAs(100) surfaces and that a second chemical cleaning step using a strong acid is required to remove residual surface oxide. This two-step cleaning process leaves the surface oxide free and with approximately 0.4 ML of elemental phosphorus, which is removed by vacuum annealing. The carbon coverage is also reduced dramatically from approximately 1 to about 0.05 ML. The chemical reactions are investigated, the resulting InP surface species at different cleaning stages are determined, and the optimum cleaning procedure is presented.

  19. The measurement of surface roughness to determine the suitability of different methods for stone cleaning

    NASA Astrophysics Data System (ADS)

    Vazquez-Calvo, Carmen; Alvarez de Buergo, Monica; Fort, Rafael; Varas-Muriel, Maria Jose

    2012-08-01

    The roughness of stone surface was measured, before and after bead blasting-based cleaning methods, to select the most efficient one to be used in masonry and stonework of specific areas of the Cathedral of Segovia (Spain). These types of cleaning methods can, besides the removal of soiling and surface deposits, leave a rougher surface, which would mean higher and more rapid water retention and deposit accumulation due to a specific surface increase, therefore accelerating stone decay. Or, in contrast, the cleaning method can be so aggressive that it can smooth the surface by reducing its roughness, a fact that usually corresponds to excessive material removal—soot and deposits--but also part of the stone substrate. Roughness results were complemented with scanning electron microscopy observations and analyses and colour measurements. Finally, it was possible to select the best cleaning method among the six that were analysed, for different areas and different stone materials. Therefore, this study confirms the measurement of surface roughness as a reliable test to determine the suitability of stone cleaning methods; it is a non-destructive technique, portable and friendly to use, which can help us to rapidly assess—together with other techniques—the efficacy and aggressiveness of the stone cleaning method.

  20. Nd:YAG Laser Cleaning of Red Stone Materials: Evaluation of the Damage

    NASA Astrophysics Data System (ADS)

    Colombo, C.; Martoni, E.; Realini, M.; Sansonetti, A.; Valentini, G.

    Lasers have been tested, during the recent past, as a useful cleaning method in conservation treatments: this is due to selectivity and precision of its performance. Nevertheless some colour changes have been detected using Nd:YAG laser sources, especially on white and red coloured substrates. Colour changes on white marble and other white architectural materials have already been widely surveyed. This chapter focuses on the interaction of laser radiation with two kinds of red materials: red Verona limestone and terracotta. These materials have been chosen because of their large use in northern Italian architecture and in statuary. Red Verona limestone is not homogenous in hue, owing to the presence of calcareous nodules (lighter in colour) and clay veins (dark reddish colour).

  1. Impact of different cleaning processes on the laser damage threshold of antireflection coatings for Z-Backlighter optics at Sandia National Laboratories

    DOE PAGES

    Field, Ella; Bellum, John; Kletecka, Damon

    2014-11-06

    We have examined how different cleaning processes affect the laser-induced damage threshold of antireflection coatings for large dimension, Z-Backlighter laser optics at Sandia National Laboratories. Laser damage thresholds were measured after the coatings were created, and again 4 months later to determine which cleaning processes were most effective. There is a nearly twofold increase in laser-induced damage threshold between the antireflection coatings that were cleaned and those that were not cleaned. Aging of the coatings after 4 months resulted in even higher laser-induced damage thresholds. Also, the laser-induced damage threshold results revealed that every antireflection coating had a high defectmore » density, despite the cleaning process used, which indicates that improvements to either the cleaning or deposition processes should provide even higher laser-induced damage thresholds.« less

  2. Impact of different cleaning processes on the laser damage threshold of antireflection coatings for Z-Backlighter optics at Sandia National Laboratories

    SciTech Connect

    Field, Ella; Bellum, John; Kletecka, Damon

    2014-11-06

    We have examined how different cleaning processes affect the laser-induced damage threshold of antireflection coatings for large dimension, Z-Backlighter laser optics at Sandia National Laboratories. Laser damage thresholds were measured after the coatings were created, and again 4 months later to determine which cleaning processes were most effective. There is a nearly twofold increase in laser-induced damage threshold between the antireflection coatings that were cleaned and those that were not cleaned. Aging of the coatings after 4 months resulted in even higher laser-induced damage thresholds. Also, the laser-induced damage threshold results revealed that every antireflection coating had a high defect density, despite the cleaning process used, which indicates that improvements to either the cleaning or deposition processes should provide even higher laser-induced damage thresholds.

  3. Investigation of EUV haze defect: molecular behaviors of mask cleaning chemicals on EUV mask surfaces

    NASA Astrophysics Data System (ADS)

    Choi, Jaehyuck; Novak, Steve; Kandel, Yudhishthir; Denbeaux, Greg; Lee, Han-shin; Ma, Andy; Goodwin, Frank

    2012-03-01

    Photo-induced defects (or haze defects) on 193nm optic masks (haze defects) have been a serious problem not only to reticle engineers working for mask manufacturing and handling but also to photo-lithography engineers. The most widely accepted explanation of the root causes of haze defects is the cleaning chemical residues remaining on the mask surface and unavoidable outgassed molecules that outgas from pellicle materials when exposed to 193nm radiation. These have been significant challenges for reticle cleaning engineers who need to use cleaning chemicals whose residues do not lead to progressive defect formation on the mask and to find improved materials to minimize pellicle outgassing. It is assumed that contamination generation on EUV masks would have a higher probability than on optic masks, primarily since EUV masks are not protected by a pellicle and amorphous carbon films can accumulate during exposure to EUV light. While there is potential to mitigate the generation of carbon contamination by improving the exposure tool environment and removing carbon films using in-situ atomic hydrogen cleaning, it is not yet clear whether the reaction of mask cleaning chemicals to EUV radiation will lead to creation of progressive defects on EUV mask surfaces. With the work to being done it has been observed that carbon contamination on EUV masks dominates any effects of solvent chemicals under normal environmental or exposure conditions (from atmospheric pressure up to a vacuum level of 10-6 Torr) during EUV exposure. However, it is still unknown whether residual cleaning chemicals will provide a nucleus for progressive defect formation during exposure. This lack of understanding needs to be addressed by the industry as EUV masks are expected to undergo more frequent cleaning cycles. In this work, we will report on an investigation of the molecular behavior of cleaning chemicals on EUV mask surfaces during EUV exposure. Movement (e.g., migration or aggregation) of

  4. Establishing reliable good initial quantum efficiency and in-situ laser cleaning for the copper cathodes in the RF gun

    NASA Astrophysics Data System (ADS)

    Zhou, F.; Sheppard, J. C.; Vecchione, T.; Jongewaard, E.; Brachmann, A.; Corbett, J.; Gilevich, S.; Weathersby, S.

    2015-05-01

    Establishing good initial quantum efficiency (QE) and reliable in-situ cleaning for copper cathode in the RF gun is of critical importance for the RF gun operations. Recent studies on the SLAC RF gun test bed indicated that the pre-cleaning (plasma cleaning) in the test chamber followed by copper cathode exposure to air for cathode change leads to a very low initial QE in the RF gun, and also demonstrated that without the pre-cleaning good initial QE >4×10-5 can be routinely achieved in the RF gun with the cathodes of QE <1×10-7 measured in the test chamber. QE can decay over the time in the RF gun. The in-situ laser cleaning technique for copper cathodes in the RF gun is established and refined in comparison to previous cleaning at the linac coherent light source, resulting in an improved QE and emittance evolutions. The physics of the laser cleaning process is discussed. It is believed that the reflectivity change is one of the major factors for the QE boost with the laser cleaning.

  5. Repellent materials. Robust self-cleaning surfaces that function when exposed to either air or oil.

    PubMed

    Lu, Yao; Sathasivam, Sanjayan; Song, Jinlong; Crick, Colin R; Carmalt, Claire J; Parkin, Ivan P

    2015-03-01

    Superhydrophobic self-cleaning surfaces are based on the surface micro/nanomorphologies; however, such surfaces are mechanically weak and stop functioning when exposed to oil. We have created an ethanolic suspension of perfluorosilane-coated titanium dioxide nanoparticles that forms a paint that can be sprayed, dipped, or extruded onto both hard and soft materials to create a self-cleaning surface that functions even upon emersion in oil. Commercial adhesives were used to bond the paint to various substrates and promote robustness. These surfaces maintained their water repellency after finger-wipe, knife-scratch, and even 40 abrasion cycles with sandpaper. The formulations developed can be used on clothes, paper, glass, and steel for a myriad of self-cleaning applications. PMID:25745169

  6. Repellent materials. Robust self-cleaning surfaces that function when exposed to either air or oil.

    PubMed

    Lu, Yao; Sathasivam, Sanjayan; Song, Jinlong; Crick, Colin R; Carmalt, Claire J; Parkin, Ivan P

    2015-03-01

    Superhydrophobic self-cleaning surfaces are based on the surface micro/nanomorphologies; however, such surfaces are mechanically weak and stop functioning when exposed to oil. We have created an ethanolic suspension of perfluorosilane-coated titanium dioxide nanoparticles that forms a paint that can be sprayed, dipped, or extruded onto both hard and soft materials to create a self-cleaning surface that functions even upon emersion in oil. Commercial adhesives were used to bond the paint to various substrates and promote robustness. These surfaces maintained their water repellency after finger-wipe, knife-scratch, and even 40 abrasion cycles with sandpaper. The formulations developed can be used on clothes, paper, glass, and steel for a myriad of self-cleaning applications.

  7. Robust self-cleaning surfaces that function when exposed to either air or oil

    NASA Astrophysics Data System (ADS)

    Lu, Yao; Sathasivam, Sanjayan; Song, Jinlong; Crick, Colin R.; Carmalt, Claire J.; Parkin, Ivan P.

    2015-03-01

    Superhydrophobic self-cleaning surfaces are based on the surface micro/nanomorphologies; however, such surfaces are mechanically weak and stop functioning when exposed to oil. We have created an ethanolic suspension of perfluorosilane-coated titanium dioxide nanoparticles that forms a paint that can be sprayed, dipped, or extruded onto both hard and soft materials to create a self-cleaning surface that functions even upon emersion in oil. Commercial adhesives were used to bond the paint to various substrates and promote robustness. These surfaces maintained their water repellency after finger-wipe, knife-scratch, and even 40 abrasion cycles with sandpaper. The formulations developed can be used on clothes, paper, glass, and steel for a myriad of self-cleaning applications.

  8. Diffusion of silver over atomically clean silicon surfaces

    SciTech Connect

    Dolbak, A. E. Ol'shanetskii, B. Z.

    2013-06-15

    The diffusion of silver the (111), (100), and (110) silicon surfaces is studied by Auger electron spectroscopy and low-energy electron diffraction. The mechanisms of diffusion over the (111) and (110) surfaces are revealed, and the temperature dependences of diffusion coefficients are measured. An anisotropy of silver diffusion over the (110) surface is detected.

  9. New method of space debris cleaning based on light negative force: tractor laser

    NASA Astrophysics Data System (ADS)

    Sun, Qiongge; Gao, Long; Li, Chen

    2016-01-01

    This paper presents a new way of space debris removal and protection, that is, using tractor laser, which based on light negative force, to achieve space debris cleaning and shielded. Tractor laser is traceable from the theory of optical tweezers, accompanied with non-diffraction beam. These kind of optical beams have the force named negative force pointing to optical source, this will bring the object along the trajectory of laser beam moving to the optical source. The negative force leads to the new method to convey and sampling the space micro-objects. In this paper, the application of tractor laser in the space debris collection and protection of 1cm is studied. The application of the several tractor beams in the space debris and sample collection is discussed. The proposed method can reduce the requirements of the laser to the satellite platform, and realize the collection of space debris, make the establishment of the space garbage station possible, and help to study the spatial non contact sample transmission and reduce the risk of space missions.

  10. Surface oxidation of GaN(0001): Nitrogen plasma-assisted cleaning for ultrahigh vacuum applications

    SciTech Connect

    Gangopadhyay, Subhashis; Schmidt, Thomas Kruse, Carsten; Figge, Stephan; Hommel, Detlef; Falta, Jens

    2014-09-01

    The cleaning of metal-organic vapor-phase epitaxial GaN(0001) template layers grown on sapphire has been investigated. Different procedures, performed under ultrahigh vacuum conditions, including degassing and exposure to active nitrogen from a radio frequency nitrogen plasma source have been compared. For this purpose, x-ray photoelectron spectroscopy, reflection high-energy electron diffraction, and scanning tunneling microscopy have been employed in order to assess chemical as well as structural and morphological surface properties. Initial degassing at 600 °C under ultrahigh vacuum conditions only partially eliminates the surface contaminants. In contrast to plasma assisted nitrogen cleaning at temperatures as low as 300 °C, active-nitrogen exposure at temperatures as high as 700 °C removes the majority of oxide species from the surface. However, extended high-temperature active-nitrogen cleaning leads to severe surface roughening. Optimum results regarding both the removal of surface oxides as well as the surface structural and morphological quality have been achieved for a combination of initial low-temperature plasma-assisted cleaning, followed by a rapid nitrogen plasma-assisted cleaning at high temperature.

  11. Surface Analysis Evaluation of Handwipe Cleaning for the Space Shuttle RSRM

    NASA Technical Reports Server (NTRS)

    Lesley, Michael W.; Anderson, Erin L.; McCool, Alex (Technical Monitor)

    2001-01-01

    In this paper we discuss the role of surface-sensitive spectroscopy (electron spectroscopy for chemical analysis, or ESCA) in the selection of solvents to replace 1,1,1-trichloroethane in handwipe cleaning of bonding surfaces on NASA's Space Shuttle Reusable Solid Rocket Motor (RSRM). Removal of common process soils from a wide variety of metallic and polymeric substrates was characterized. The cleaning efficiency was usually more dependent on the type of substrate being cleaned and the specific process soil than on the solvent used. A few substrates that are microscopically rough or porous proved to be difficult to clean with any cleaner, and some soils were very tenacious and difficult to remove from any substrate below detection limits. Overall, the work showed that a wide variety of solvents will perform at least as well as 1,1,1-trichloroethane.

  12. Self-Cleaning Surfaces Prepared By Microstructuring System

    NASA Astrophysics Data System (ADS)

    Sabbah, Abbas; Vandeparre, H.; Brau, F.; Damman, P.

    The wettability of materials is a very important aspect of surface science governed by the chemical composition of the surface and its morphology. In this context, materials replicating nature's superhydrophobic surfaces, such as lotus leafs, rose petals and butterfly wings, have widely attracted attention of physicists and material engineers [1-3]. Despite of considerable efforts during the last decade, superhydrophobic surfaces are still expensive and usually involved microfabrication processes, such as photolithography technique. In this study, we propose an original and simple method to create superhydrophobic surfaces by controling elastic instabilities [4-8]. Indeed, we demonstrate that the self-organization of wrinkles on top of non-wettable polymer surfaces leads to surperhydrophobic surfaces.

  13. Femtosecond laser controlled wettability of solid surfaces.

    PubMed

    Yong, Jiale; Chen, Feng; Yang, Qing; Hou, Xun

    2015-12-14

    Femtosecond laser microfabrication is emerging as a hot tool for controlling the wettability of solid surfaces. This paper introduces four typical aspects of femtosecond laser induced special wettability: superhydrophobicity, underwater superoleophobicity, anisotropic wettability, and smart wettability. The static properties are characterized by the contact angle measurement, while the dynamic features are investigated by the sliding behavior of a liquid droplet. Using different materials and machining methods results in different rough microstructures, patterns, and even chemistry on the solid substrates. So, various beautiful wettabilities can be realized because wettability is mainly dependent on the surface topography and chemical composition. The distinctions of the underlying formation mechanism of these wettabilities are also described in detail. PMID:26415826

  14. The impact of different cleaning processes on the laser damage threshold of antireflection coatings for Z-Backlighter optics at Sandia National Laboratories

    NASA Astrophysics Data System (ADS)

    Field, Ella; Bellum, John; Kletecka, Damon

    2014-09-01

    The Z-Backlighter lasers at Sandia National Laboratories are kilojoule class, pulsed systems operating with ns pulse lengths at 527 nm and ns and sub-ps pulse lengths at 1054 nm (www.z-beamlet.sandia.gov), and are linked to the most powerful and energetic x-ray source in the world, the Z-Accelerator (http://www.sandia.gov/z-machine/). An important Z-Backlighter optic is a flat, fused silica optic measuring 32.5 cm × 32.5 cm × 1 cm with an antireflection (AR) coating on both sides. It is used as a debris shield to protect other Z-Backlighter laser optics from high-velocity particles released by the experiments conducted in the Z-Accelerator. Each experiment conducted in the Z-Accelerator releases enough debris to cloud the surface of a debris shield, which means that a debris shield cannot be used for more than one experiment. Every year, the large optics coating facility [1] at Sandia provides AR coatings for approximately 50 debris shields, in addition to AR coatings for numerous other meter-class Z-Backlighter lenses and windows. As with all Z-Backlighter optical coatings, these AR coatings must have a high laser-induced damage threshold (LIDT) in order to withstand the powerful Z-Backlighter laser fluences. Achieving a good LIDT depends not only on the coating deposition processes but also on the polishing and cleaning processes used to prepare the coated and uncoated surfaces [2]. We spend a lot of time, both before and after the coatings have been deposited, manually cleaning the optics, including the debris shields, even though they are an expendable type of optic. Therefore, in this study we have tested new cleaning methods in addition to our current method to determine their impact on the LIDT of AR coatings, and conclude whether a shorter-duration or less labor-intensive cleaning process would suffice.

  15. Adhesion of metals to a clean iron surface studied with LEED and Auger emission spectroscopy.

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1972-01-01

    Discussion of the results of adhesion experiments conducted with various metals contacting a clean iron surface. The metals included gold, silver, nickel, platinum, lead, tantalum, aluminum, and cobalt. Some of the metals were examined with oxygen present on their surface as well as in the clean state. The results indicate that, with the various metals contacting iron, the cohesively weaker will adhere and transfer to the cohesively stronger. The chemical activity of the metal also influenced the adhesive forces measured. With oxygen present on the metal surface, the adhesive forces measured could be correlated with the binding energy of the metal to oxygen.

  16. Quantum Efficiency and Topography of Heated and Plasma-Cleaned Copper Photocathode Surfaces

    SciTech Connect

    Palmer, Dennis T.; Kirby, R.E.; King, F.K.; /SLAC

    2005-08-04

    We present measurements of photoemission quantum efficiency (QE) for copper photocathodes heated and cleaned by low energy argon and hydrogen ion plasma. The QE and surface roughness parameters were measured before and after processing and surface chemical composition was tracked in-situ with x-ray photoelectron spectroscopy (XPS). Thermal annealing at 230 C was sufficient to improve the QE by 3-4 orders of magnitude, depending on the initial QE. Exposure to residual gas slowly reduced the QE but it was easily restored by argon ion cleaning for a few minutes. XPS showed that the annealing or ion bombardment removed surface water and hydrocarbons.

  17. Control of pyrite surface chemistry in physical coal cleaning

    SciTech Connect

    Luttrell, G.H.; Yoon, R.H.; Zachwieja, J.; Lagno, M.

    1992-06-24

    To better understand the surface chemical properties of coal and mineral pyrite, studies on the effect of flotation surfactants (frother and kerosene) on the degree of hydrophobicity have been conducted. The presence of either frother or kerosene enhanced the flotability of coal and mineral pyrite with a corresponding decrease in induction time over the pH range examined. Scanning electron microscopy (SEM) results indicate a correlation exists between the sample surface morphology and crystal structure and the observed hydrophobicity. As a result of the data obtained from the surface characterization studies, controlled surface oxidation was investigated as a possible pyrite rejection scheme in microbubble column flotation.

  18. Laser surface treatment of amorphous metals

    NASA Astrophysics Data System (ADS)

    Katakam, Shravana K.

    Amorphous materials are used as soft magnetic materials and also as surface coatings to improve the surface properties. Furthermore, the nanocrystalline materials derived from their amorphous precursors show superior soft magnetic properties than amorphous counter parts for transformer core applications. In the present work, laser based processing of amorphous materials will be presented. Conventionally, the nanocrystalline materials are synthesized by furnace heat treatment of amorphous precursors. Fe-based amorphous/nanocrystalline materials due to their low cost and superior magnetic properties are the most widely used soft magnetic materials. However, achieving nanocrystalline microstructure in Fe-Si-B ternary system becomes very difficult owing its rapid growth rate at higher temperatures and sluggish diffusion at low temperature annealing. Hence, nanocrystallization in this system is achieved by using alloying additions (Cu and Nb) in the ternary Fe-Si-B system. Thus, increasing the cost and also resulting in reduction of saturation magnetization. laser processing technique is used to achieve extremely fine nanocrystalline microstructure in Fe-Si-B amorphous precursor. Microstructure-magnetic Property-laser processing co-relationship has been established for Fe-Si-B ternary system using analytical techniques. Laser processing improved the magnetic properties with significant increase in saturation magnetization and near zero coercivity values. Amorphous materials exhibit excellent corrosion resistance by virtue of their atomic structure. Fe-based amorphous materials are economical and due to their ease of processing are of potential interest to synthesize as coatings materials for wear and corrosion resistance applications. Fe-Cr-Mo-Y-C-B amorphous system was used to develop thick coatings on 4130 Steel substrate and the corrosion resistance of the amorphous coatings was improved. It is also shown that the mode of corrosion depends on the laser processing

  19. Control of pyrite surface chemistry in physical coal cleaning

    SciTech Connect

    Luttrell, G.H.; Yoon, R.H.; Zachwieja, J.B.; Lagno, M.L.

    1992-06-24

    Correlation of the hydrophobicity measurements of coal and mineral pyrite with changes in the surface composition of the samples as determined by x-ray photoelectron spectroscopy (XPS) reveals that similar surface oxidation products are found on both mineral and coal pyrite samples. The surface oxidation layer of these samples is comprised of different amounts of hydrophilic species (iron hydroxy-oxides and/or iron oxides) and hydrophobic species (polysulfide or elemental sulfur). The resulting hydrophobicity of these samples may be attributed to the ratio of hydrophilic (surface oxides) to hydrophobic (sulfur-containing) species in the surface oxidation layer. Also, coal pyrite samples were found to exhibit a greater degree of superficial oxidation and a less hydrophobic character as compared to the mineral pyrite samples.

  20. Oxalic acid adsorption states on the clean Cu(110) surface

    NASA Astrophysics Data System (ADS)

    Fortuna, Sara

    2016-11-01

    Carboxylic acids are known to assume a variety of configurations on metallic surfaces. In particular oxalic acid on the Cu(110) surface has been proposed to assume a number of upright configurations. Here we explore with DFT calculations the possible structures that oxalic acid can form on copper 110 at different protonation states, with particular attention at the possibility of forming structures composed of vertically standing molecules. In its fully protonated form it is capable of anchoring itself on the surface thanks to one of its hydrogen-free oxygens. We show the monodeprotonated upright molecule with two oxygens anchoring it on the surface to be the lowest energy conformation of a single oxalic molecules on the Cu(110) surface. We further show that it is possible for this configuration to form dense hexagonally arranged patterns in the unlikely scenario in which adatoms are not involved.

  1. [INVITED] Laser treatment of Inconel 718 alloy and surface characteristics

    NASA Astrophysics Data System (ADS)

    Yilbas, B. S.; Ali, H.; Al-Aqeeli, N.; Karatas, C.

    2016-04-01

    Laser surface texturing of Inconel 718 alloy is carried out under the high pressure nitrogen assisting gas. The combination of evaporation and melting at the irradiated surface is achieved by controlling the laser scanning speed and the laser output power. Morphological and metallurgical changes in the treated surface are analyzed using the analytical tools including optical, electron scanning, and atomic force microscopes, energy dispersive spectroscopy, and X-ray diffraction. Microhardnes and friction coefficient of the laser treated surface are measured. Residual stress formed in the surface region is determined from the X-ray diffraction data. Surface hydrophobicity of the laser treated layer is assessed incorporating the sessile drop method. It is found that laser treated surface is free from large size asperities including cracks and the voids. Surface microhardness increases significantly after the laser treatment process, which is attributed to the dense layer formation at the surface under the high cooling rates, dissolution of Laves phase in the surface region, and formation of nitride species at the surface. Residual stress formed is compressive in the laser treated surface and friction coefficient reduces at the surface after the laser treatment process. The combination of evaporation and melting at the irradiated surface results in surface texture composes of micro/nano-poles and pillars, which enhance the surface hydrophobicity.

  2. Laser-ultrasonic hardening of the surface of steel

    SciTech Connect

    Gureev, D M

    1998-03-31

    An investigation was made of the feasibility of laser-ultrasonic hardening of the surface of steel with a controlled change in the structurally stressed state of the surface layer. The advantages of the laser-ultrasonic treatment were demonstrated by the formation of harder and deeper surface hardening zones with simultaneous control of their structure and phase composition and of the formation of residual stresses. (interaction of laser radiation with matter. laser plasma)

  3. Focusing of Intense Laser via Parabolic Plasma Concave Surface

    NASA Astrophysics Data System (ADS)

    Zhou, Weimin; Gu, Yuqiu; Wu, Fengjuan; Zhang, Zhimeng; Shan, Lianqiang; Cao, Leifeng; Zhang, Baohan

    2015-12-01

    Since laser intensity plays an important role in laser plasma interactions, a method of increasing laser intensity - focusing of an intense laser via a parabolic plasma concave surface - is proposed and investigated by three-dimensional particle-in-cell simulations. The geometric focusing via a parabolic concave surface and the temporal compression of high harmonics increased the peak intensity of the laser pulse by about two orders of magnitude. Compared with the improvement via laser optics approaches, this scheme is much more economic and appropriate for most femtosecond laser facilities. supported by National Natural Science Foundation of China (Nos. 11174259, 11175165), and the Dual Hundred Foundation of China Academy of Engineering Physics

  4. In vitro studies on the effect of cleaning methods on different implant surfaces.

    PubMed

    Augthun, M; Tinschert, J; Huber, A

    1998-08-01

    The effect of specific cleaning procedures was examined on the surfaces of 3 implant types with different coatings and shapes (plasma sprayed [PS]; hydroxyapatite coated [HA] implants; and smooth titanium surface screws) using a scanning electron microscope. Each implant was treated for 60 seconds per instrument with one of 6 different hygiene measures: plastic curet, metal curet, diamond polishing device, ultrasonic scaler, air-powder-water spray with sodium hydrocarbonate solution, and chlorhexidine 0.1% solution rinse. The air-powder-abrasive system, chlorhexidine rinse, and curettage with a plastic instrument caused little or no surface damage in all but the hydroxyapatite-coated fixtures. Therefore, these 3 methods were tested to determine their cleaning efficacy in a second clinical study, which did not include the HA-coated fixture. Two implants were placed on the facial aspects of both upper molar regions using individual acrylic plates. Thus, 2 fixtures on each side were examined in each patient. The examination revealed that only the sodium hydrocarbonate spray yielded a clean fixture without damage to the implant surface. In a third stage, which imitated the clinical procedure of the second approach, the cell growth of mouse-fibroblasts on implant surfaces was examined after cleaning the surface with plastic scaler and the air-abrasive system, which represents the least damaging and most effective methods. In contrast to the implant surfaces treated with plastic scalers, mostly vital cells were found on implants sprayed with the air-abrasive system. PMID:9736367

  5. Self-cleaning skin-like prosthetic polymer surfaces

    DOEpatents

    Simpson, John T.; Ivanov, Ilia N.; Shibata, Jason

    2012-03-27

    An external covering and method of making an external covering for hiding the internal endoskeleton of a mechanical (e.g., prosthetic) device that exhibits skin-like qualities is provided. The external covering generally comprises an internal bulk layer in contact with the endoskeleton of the prosthetic device and an external skin layer disposed about the internal bulk layer. The external skin layer is comprised of a polymer composite with carbon nanotubes embedded therein. The outer surface of the skin layer has multiple cone-shaped projections that provide the external skin layer with superhydrophobicity. The carbon nanotubes are preferably vertically aligned between the inner surface and outer surface of the external skin layer in order to provide the skin layer with the ability to transmit heat. Superhydrophobic powders may optionally be used as part of the polymer composite or applied as a coating to the surface of the skin layer to enhance superhydrophobicity.

  6. Electrical and Surface Properties of InAs/InSb Nanowires Cleaned by Atomic Hydrogen.

    PubMed

    Webb, James L; Knutsson, Johan; Hjort, Martin; Gorji Ghalamestani, Sepideh; Dick, Kimberly A; Timm, Rainer; Mikkelsen, Anders

    2015-08-12

    We present a study of InAs/InSb heterostructured nanowires by X-ray photoemission spectroscopy (XPS), scanning tunneling microscopy (STM), and in-vacuum electrical measurements. Starting with pristine nanowires covered only by the native oxide formed through exposure to ambient air, we investigate the effect of atomic hydrogen cleaning on the surface chemistry and electrical performance. We find that clean and unreconstructed nanowire surfaces can be obtained simultaneously for both InSb and InAs by heating to 380 ± 20 °C under an H2 pressure 2 × 10(-6) mbar. Through electrical measurement of individual nanowires, we observe an increase in conductivity of 2 orders of magnitude by atomic hydrogen cleaning, which we relate through theoretical simulation to the contact-nanowire junction and nanowire surface Fermi level pinning. Our study demonstrates the significant potential of atomic hydrogen cleaning regarding device fabrication when high quality contacts or complete control of the surface structure is required. As hydrogen cleaning has recently been shown to work for many different types of III-V nanowires, our findings should be applicable far beyond the present materials system.

  7. Fluid drag reduction and efficient self-cleaning with rice leaf and butterfly wing bioinspired surfaces

    NASA Astrophysics Data System (ADS)

    Bixler, Gregory D.; Bhushan, Bharat

    2013-08-01

    Researchers are continually inspired by living nature to solve complex challenges. For example, unique surface characteristics of rice leaves and butterfly wings combine the shark skin (anisotropic flow leading to low drag) and lotus leaf (superhydrophobic and self-cleaning) effects, producing the so-called rice and butterfly wing effect. In this paper, we present an overview of rice leaf and butterfly wing fluid drag and self-cleaning studies. In addition, we examine two other promising aquatic surfaces in nature known for such properties, including fish scales and shark skin. Morphology, drag, self-cleaning, contact angle, and contact angle hysteresis data are presented to understand the role of wettability, viscosity, and velocity. Liquid repellent coatings are utilized to recreate or combine various effects. Discussion is provided along with conceptual models describing the role of surface structures related to low drag, self-cleaning, and antifouling properties. Modeling provides design guidance when developing novel low drag and self-cleaning surfaces for applications in the medical, marine, and industrial fields.

  8. Fluid drag reduction and efficient self-cleaning with rice leaf and butterfly wing bioinspired surfaces.

    PubMed

    Bixler, Gregory D; Bhushan, Bharat

    2013-09-01

    Researchers are continually inspired by living nature to solve complex challenges. For example, unique surface characteristics of rice leaves and butterfly wings combine the shark skin (anisotropic flow leading to low drag) and lotus leaf (superhydrophobic and self-cleaning) effects, producing the so-called rice and butterfly wing effect. In this paper, we present an overview of rice leaf and butterfly wing fluid drag and self-cleaning studies. In addition, we examine two other promising aquatic surfaces in nature known for such properties, including fish scales and shark skin. Morphology, drag, self-cleaning, contact angle, and contact angle hysteresis data are presented to understand the role of wettability, viscosity, and velocity. Liquid repellent coatings are utilized to recreate or combine various effects. Discussion is provided along with conceptual models describing the role of surface structures related to low drag, self-cleaning, and antifouling properties. Modeling provides design guidance when developing novel low drag and self-cleaning surfaces for applications in the medical, marine, and industrial fields.

  9. Control of pyrite surface chemistry in physical coal cleaning

    SciTech Connect

    Yoon, R.H.; Luttrell, G.H.; Zachwieja, J.B.; Mielczarski, J.A.

    1992-03-18

    The separation of pyrite from coal by flotation is based on exploiting the wettability difference between coal and pyrite. There is evidence that the wettability of coal pyrite changes upon superficial oxidation. Therefore, the oxidation of coal pyrite has been studied under carefully controlled electrochemical conditions. In order to identify the species responsible for the changes in wettability, the surface products formed during oxidation have been identified by means of various surface analysis techniques, including X-ray photoelectron spectroscopy (XPS) and ion scattering spectroscopy (ISS). It has been found that pyrite oxidation creates a sulfur-rich surface along with iron oxides/hydroxides. The ratio between these hydrophobic and hydrophilic species correlates well with the results of the wettability measurements.

  10. Friction-induced surface activity of some hydrocarbons with clean and oxide-covered iron

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1973-01-01

    Sliding friction studies were conducted on a clean and oxide-covered iron surface with exposure of that surface to various hydrocarbons. The hydrocarbons included ethane, ethylene ethyl chloride, methyl chloride, and vinyl chloride. Auger cylindrical mirror analysis was used to follow interactions of the hydrocarbon with the iron surface. Results with vinyl chloride indicate friction induced surface reactivity, adsorption to surface oxides, friction sensitivity to concentration and polymerization. Variation in the loads employed influence adsorption and accordingly friction. In contrast with ethyl and vinyl chloride, friction induced surface reactivity was not observed with ethane and ethylene.

  11. Surface Analytical Study of Cleaning Effects and the Progress of Contamination on Prototypes of the Kilogram

    NASA Astrophysics Data System (ADS)

    Ikeda, S.; Uchikawa, K.; Hashiguchi, Y.; Nagoshi, M.; Kasamura, H.; Shiozawa, K.; Fujita, D.; Yoshihara, K.

    1993-01-01

    To examine the stability of prototypes of the kilogram after cleaning, surface analysis techniques, including X-ray photoelectron spectroscopy (XPS), were applied to specimens cut from prototype material of Pt-10% Ir alloy. Traditional steam-jet cleaning (SJC) was compared with ultrasonic cleaning with solvents (UCS) in terms of cleaning effects and the progress of contamination. The results show that mass changes due to metallic factors such as oxidation, reduction and dissolution were negligibly small. In terms of carbon decrease and adsorption of water, UCS was superior to SJC. From analyses of peak area ratio by XPS, it was shown that the cleaner the surfaces, the higher the rate of contamination. But the contamination levels converged to a common value after a six-month exposure to air, irrespective of the cleaning method used. This finding is of great importance for the preservation of prototypes. The contaminating substances were found to be hydrocarbons from the ambient air. The mass gain for the surfaces of a prototype due to hydrocarbons after a six-month exposure to ambient air is estimated to be 4,3 μg for SJC and 16 μg for UCS.

  12. Surface cleaning effects on reliability for devices with ultrathin oxides or oxynitrides

    NASA Astrophysics Data System (ADS)

    Lai, Kafai; Hao, Ming-Yin; Chen, Wei-Ming; Lee, Jack C.

    1994-09-01

    A new wafer cleaning procedure has been developed for ultra-thin thermal oxidation process (clean and a two-step dip, first in diluted HF and then in a methanol/HF solution, with no final DI water rinse. Ultrathin thermal oxides (48 angstrom) and oxynitrides grown in N2O (42 angstrom) were prepared using this new cleaning and other commonly used cleaning methods to investigate the effects of surface preparation on dielectric integrity. It has been found that this two-dip method produces dielectrics with reduced leakage current and stress-induced leakage current, which are believed to be the critical parameters for ultrathin oxides. Furthermore, this new cleaning procedure improves both intrinsic and defect-related breakdown as well as the uniformity of the current- voltage characteristics across a 4-inch wafer. The methanol/HF dip time has also been optimized. The improvement is believed to be due to enhanced silicon surface passivation by hydrogen, the reduced surface micro-roughness and the absence of native oxide.

  13. Control of pyrite surface chemistry in physical coal cleaning

    SciTech Connect

    Luttrell, G.H.; Yoon, R.H.; Zachwieja, J.B.

    1992-06-24

    The removal of pyrite from coal by flotation or any other surface chemistry based separation process is often hampered by the apparent hydrophobicity of the mineral. Results obtained in this project suggest that corrosion processes are responsible for the apparent hydrophobicity of pyrite in aqueous environments. Characterization of the corrosion products of pyrite in acidic and alkaline solution has been performed using electrochemical (cyclic voltammetry and single-potential-step chronoamperometry) and spectroscopic techniques (X-ray photoelectron spectroscopy -- XPS). The nature of the surface products have been correlated with hydrophobicity determined from in-situ contact angle measurements. The results show that pyrite hydrophobicity is influenced by either the oxidation or reduction conditions of the system.

  14. Coal surface control for advanced physical fine coal cleaning technologies

    SciTech Connect

    Morsi, B.I.; Chiang, S-H.; Sharkey, A.; Blachere, J.; Klinzing, G.; Araujo, G.; Venkatadri, R.; Bi, H.; Campbell, P.; Ciocco, M.; Hittle, L.; Kim, S.; Kim, Y.; Perez, L.

    1990-01-01

    Research continued on surface control of coal. This report describes Task 7 of the program. The following topics are discussed: quantitative distribution of iron species; surface functional groups; comparison of wet and dry ground samples; study of Illinois No. 6 coal wet ground using additives; study of wet grinding using tall oil; elemental distribution of coal samples wet ground without additives; elemental distribution of coal samples wet ground with tall oil; direct determination of pyrite by x-ray diffraction; electron microprobe measurements; morphology; zeta potential measurements; pyrite size distribution; statistical analysis of grinding study data; grinding using N-pentane; cyclohexane, and N-heptane; study of the effects of the grinding method and time; study of the effects of the agglomeration time; and the pentane to coal ratio. 13 refs.

  15. Surface chemistry and fundamental limitations on the plasma cleaning of metals

    NASA Astrophysics Data System (ADS)

    Dong, Bin; Driver, M. Sky; Emesh, Ismail; Shaviv, Roey; Kelber, Jeffry A.

    2016-10-01

    In-situ X-ray photoelectron spectroscopy (XPS) studies reveal that plasma cleaning of air-exposed Co or Cu transition metal surfaces results in the formation of a remnant C film 1-3 monolayers thick, which is not reduced upon extensive further plasma exposure. This effect is observed for H2 or NH3 plasma cleaning of Co, and He or NH3 plasma cleaning of Cu, and is observed with both inductively coupled (ICP) and capacitively-coupled plasma (CCP). Changes in C 1 s XPS spectra indicate that this remnant film formation is accompanied by the formation of carbidic C on Co and of graphitic C on Cu. This is in contrast to published work showing no such remnant carbidic/carbon layer after similar treatments of Si oxynitride surfaces. The observation of the remnant carbidic C film on Co and graphitic film on Cu, but not on silicon oxynitride (SiOxNy), regardless of plasma chemistry or type, indicates that this effect is due to plasma induced secondary electron emission from the metal surface, resulting in transformation of sp3 adventitious C to either a metal carbide or graphite. These results suggest fundamental limitations to plasma-based surface cleaning procedures on metal surfaces.

  16. Laser forming micro geometric structures on the surface of roller rolling mill

    NASA Astrophysics Data System (ADS)

    Vasilyev, O. S.; Ruzankina, J. S.

    2016-08-01

    This paper presents a method of metal surface microstructuring by means of radiation of an impulse fiber laser with a scanning system, used for the displacement of the light beam. The topographic relief being presented was modeled in the graphics editor and then was manufactured on the experimental material. We also created a "parameter matrix", which allows to determine the optimal modes of operation of the laser system for treatment of a specific material. The paper describes three stages of the microstructuring process: profiling, cleaning, and polishing, and the corresponding geometrical parameters of the structures manufactured. A method for decreasing the level of relief roughness (for Ra and Rz) was developed.

  17. Laser Patterning of Diamond. Part II. Surface Nondiamond Carbon Formation and its Removal

    SciTech Connect

    Smedley, J.; Jaye, C; Bohon, J; Rao, T; Fischer, D

    2009-01-01

    As diamond becomes more prevalent for electronic and research applications, methods of patterning diamond will be required. One such method, laser ablation, has been investigated in a related work. We report on the formation of surface nondiamond carbon during laser ablation of both polycrystalline and single-crystal synthetic diamonds. Near edge x-ray absorption fine structure spectroscopy was used to confirm that the nondiamond carbon layer formed during the ablation was amorphous, and Fourier transform infrared absorption spectroscopy (FTIR) was used to estimate the thickness of this layer to be {approx} 60 nm. Ozone cleaning was used to remove the nondiamond carbon layer.

  18. Effective removal of field-emitting sites from metallic surfaces by dry ice cleaning

    SciTech Connect

    Dangwal, Arti; Mueller, Guenter; Reschke, Detlef; Floettmann, Klaus; Singer, Xenia

    2007-08-15

    Systematic results of the field emission properties of polycrystalline copper and niobium and single-crystal Nb are reported. Dry ice cleaning (DIC) is found to suppress enhanced field emission from metallic surfaces. The cleaning effect on the emitting sites was investigated by means of field emission scanning microscopy up to fields of 250 MV/m and high-resolution scanning electron microscopy with energy dispersive x-ray analysis. The number density of emitters at given fields was drastically reduced by dry ice cleaning. Current-voltage measurements and derived Fowler-Nordheim parameters are partially discussed with respect to the morphology and impurity content of localized emitters. No emission from grain boundaries on large-grain Nb samples was observed. The microscopy results prove the effective removal of field-emitting particulates down to 400 nm as well as the partial smoothing of surface protrusions by DIC.

  19. Examining factors that influence the effectiveness of cleaning antineoplastic drugs from drug preparation surfaces: a pilot study.

    PubMed

    Hon, Chun-Yip; Chua, Prescillia Ps; Danyluk, Quinn; Astrakianakis, George

    2014-06-01

    Occupational exposure to antineoplastic drugs has been documented to result in various adverse health effects. Despite the implementation of control measures to minimize exposure, detectable levels of drug residual are still found on hospital work surfaces. Cleaning these surfaces is considered as one means to minimize the exposure potential. However, there are no consistent guiding principles related to cleaning of contaminated surfaces resulting in hospitals to adopt varying practices. As such, this pilot study sought to evaluate current cleaning protocols and identify those factors that were most effective in reducing contamination on drug preparation surfaces. Three cleaning variables were examined: (1) type of cleaning agent (CaviCide®, Phenokil II™, bleach and chlorhexidine), (2) application method of cleaning agent (directly onto surface or indirectly onto a wipe) and (3) use of isopropyl alcohol after cleaning agent application. Known concentrations of antineoplastic drugs (either methotrexate or cyclophosphamide) were placed on a stainless steel swatch and then, systematically, each of the three cleaning variables was tested. Surface wipes were collected and quantified using high-performance liquid chromatography-tandem mass spectrometry to determine the percent residual of drug remaining (with 100% being complete elimination of the drug). No one single cleaning agent proved to be effective in completely eliminating all drug contamination. The method of application had minimal effect on the amount of drug residual. In general, application of isopropyl alcohol after the use of cleaning agent further reduced the level of drug contamination although measureable levels of drug were still found in some cases.

  20. Self-Cleaning Synthetic Adhesive Surfaces Mimicking Tokay Geckos.

    SciTech Connect

    Branson, Eric D.; Singh, Seema; Burckel, David Bruce; Fan, Hongyou; Houston, Jack E.; Brinker, C. Jeffrey; Johnson, Patrick

    2006-11-01

    A gecko's extraordinary ability to suspend itself from walls and ceilings of varied surface roughness has interested humans for hundreds of years. Many theories and possible explanations describing this phenomenon have been proposed including sticky secretions, microsuckers, and electrostatic forces; however, today it is widely accepted that van der Waals forces play the most important role in this type of dry adhesion. Inarguably, the vital feature that allows a gecko's suspension is the presence of billions 3 of tiny hairs on the pad of its foot called spatula. These features are small enough to reach within van der Waals distances of any surface (spatula radius %7E100 nm); thus, the combined effect of billions of van der Waals interactions is more than sufficient to hold a gecko's weight to surfaces such as smooth ceilings or wet glass. Two lithographic approaches were used to make hierarchal structures with dimensions similar to the gecko foot dimensions noted above. One approach combined photo-lithography with soft lithography (micro-molding). In this fabrication scheme the fiber feature size, defined by the alumina micromold was 0.2 um in diameter and 60 um in height. The second approach followed more conventional photolithography-based patterning. Patterned features with dimensions %7E0.3 mm in diameter by 0.5 mm tall were produced. We used interfacial force microscopy employing a parabolic diamond tip with a diameter of 200 nm to measure the surface adhesion of these structures. The measured adhesive forces ranged from 0.3 uN - 0.6 uN, yielding an average bonding stress between 50 N/cm2 to 100 N/cm2. By comparison the reported literature value for the average stress of a Tokay gecko foot is 10 N/cm2. Acknowledgements This work was funded by Sandia National Laboratory's Laboratory Directed Research & Development program (LDRD). All coating processes were conducted in the cleanroom facility located at the University of New Mexico's Center for High Technology

  1. Laser cleaning in conservation of stone, metal, and painted artifacts: state of the art and new insights on the use of the Nd:YAG lasers

    NASA Astrophysics Data System (ADS)

    Siano, S.; Agresti, J.; Cacciari, I.; Ciofini, D.; Mascalchi, M.; Osticioli, I.; Mencaglia, A. A.

    2012-02-01

    In the present work the application of laser cleaning in the conservation of cultural assets is reviewed and some further developments on the interpretation of the associated laser-material interaction regimes are reported. Both the state of the art and new insights mainly focus on systematic approaches addressed to the solution of representative cleaning problems, including stone and metal artifacts along with wall and easel paintings. The innovative part is entirely dedicated to the extension of the application perspective of the Nd:YAG lasers by exploiting the significant versatility provided by their different pulse durations. Besides extensively discussing the specific conservation and physical problems involved in stone and metal cleaning, a significant effort was also made to explore the application potential for wall and easel paintings. The study of the latter was confined to preliminary irradiation tests carried out on prepared samples. We characterized the ablation phenomenology, optical properties, and photomechanical generation associated with the irradiation of optically absorbing varnishes using pulse durations of 10 and 120 ns. Further results concern the nature of the well-known problem of the yellowish appearance in stone cleaning, removal of biological growths and graffiti from stones, cleaning of bronze and iron artifacts and related aspects of laser conversion of unstable minerals, removal of calcareous stratification from wall paintings, and other features.

  2. Control of pyrite surface chemistry in physical coal cleaning

    SciTech Connect

    Yoon, R.H.; Richardson, P.R.

    1992-01-01

    Over the past 10 years, much research has provided convincing evidence that one major difficulty in using froth flotation to separate pyrite from coal is the self-induced'' flotation of pyrite. Numerous studies have attempted to identify reactions that occur under moderate oxidizing conditions, which lead to self-induced flotation, and to identify the oxidization products. During the past two report periods, it was established that: (1) freshly fractured pyrite surfaces immediately assume, at fracture, an electrode potential several hundred millivolts more negative than the usual steady state mixed potentials. Within minutes after fracture, the electrodes oxidize and reach higher steady state potentials. It was also shown, by photocurrent measurements, that a negative surface charge (upward band bending) already exists on freshly fractured pyrite, and (2) particle bed electrodes can be used to control the oxidation of pyrite and to precisely determine the electrochemical conditions where flotation occurs, or is depressed. By circulating the solution phase to an ultraviolet spectrometer, soluble products produced on pyrite by oxidation and reduction can be determined, e.g., HS[sup [minus

  3. Control of pyrite surface chemistry in physical coal cleaning

    SciTech Connect

    Luttrell, G.H.; Yoon, R.H.; Zachwieja, J.; Lagno, M.

    1990-01-17

    To better understand the flotation behavior of coal pyrite, studies have been initiated to characterize the floatability of coal pyrite and mineral pyrite. The hydrophobicity of coal material pyrite was examined over a range of pH and oxidation times. The results indicate that surface oxidation plays an important role in coal and mineral pyrite hydrophobicity. The hydrophobicity of mineral pyrite decreases with increasing oxidation time (20 min. to 5 hr.) and increasing pH (pH 4.6 to 9.2), with maximum depression occurring at pH 9.2. However, coal pyrite exhibited low floatability, even at the lowest oxidation time, over the entire pH range. X-ray photoelectron spectroscopy (XPS) results suggest the growth of an oxidized iron layer as being responsible for the deterioration in floatability, while a sulfur-containing species present on the sample surfaces may promote floatability. Preliminary studies of the effect of frother indicate an enhancement in the floatability of both coal and mineral pyrite over the entire pH range.

  4. Surface modification of Ti dental implants by Nd:YVO 4 laser irradiation

    NASA Astrophysics Data System (ADS)

    Braga, Francisco J. C.; Marques, Rodrigo F. C.; Filho, Edson de A.; Guastaldi, Antonio C.

    2007-09-01

    Surface modifications have been applied in endosteal bone devices in order to improve the osseointegration through direct contact between neoformed bone and the implant without an intervening soft tissue layer. Surface characteristics of titanium implants have been modified by addictive methods, such as metallic titanium, titanium oxide and hydroxyapatite powder plasma spray, as well as by subtractive methods, such as acid etching, acid etching associated with sandblasting by either AlO 2 or TiO 2, and recently by laser ablation. Surface modification for dental and medical implants can be obtained by using laser irradiation technique where its parameters like repetition rate, pulse energy, scanning speed and fluency must be taken into accounting to the appropriate surface topography. Surfaces of commercially pure Ti (cpTi) were modified by laser Nd:YVO 4 in nine different parameters configurations, all under normal atmosphere. The samples were characterized by SEM and XRD refined by Rietveld method. The crystalline phases αTi, βTi, Ti 6O, Ti 3O and TiO were formed by the melting and fast cooling processes during irradiation. The resulting phases on the irradiated surface were correlated with the laser beam parameters. The aim of the present work was to control titanium oxides formations in order to improve implants osseointegration by using a laser irradiation technique which is of great importance to biomaterial devices due to being a clean and reproducible process.

  5. Atmospheric-Pressure Plasma Cleaning of Contaminated Surfaces

    SciTech Connect

    Robert F. Hicks; Gary S. Selwyn

    2001-01-09

    Project was to develop a low-cost, environmentally benign technology for the decontamination and decommissioning of transuranic waste. With the invention of the atmospheric-pressure plasma jet the goal was achieved. This device selectively etches heavy metals from surfaces, rendering objects radiation free and suitable for decommissioning. The volatile reaction products are captured on filters, which yields a tremendous reduction in the volume of the waste. Studies on tantalum, a surrogate material for plutonium, have shown that etch rate of 6.0 microns per minute can be achieved under mild conditions. Over the past three years, we have made numerous improvements in the design of the plasma jet. It may now be operated for hundreds of hours and not undergo any degradation in performance. Furthermore, small compact units have been developed, which are easily deployed in the field.

  6. Femtosecond laser-induced electronic plasma at metal surface

    SciTech Connect

    Chen Zhaoyang; Mao, Samuel S.

    2008-08-04

    We develop a theoretical analysis to model plasma initiation at the early stage of femtosecond laser irradiation of metal surfaces. The calculation reveals that there is a threshold intensity for the formation of a microscale electronic plasma at the laser-irradidated metal surface. As the full width at half maximum of a laser pulse increases from 15 to 200 fs, the plasma formation threshold decreases by merely about 20%. The dependence of the threshold intensity on laser pulse width can be attributed to laser-induced surface electron emission, in particular due to the effect of photoelectric effect.

  7. In situ remote H-plasma cleaning of patterned Si-SiO2 surfaces

    NASA Astrophysics Data System (ADS)

    Carter, R. J.; Schneider, T. P.; Montgomery, J. S.; Nemanich, R. J.

    1994-11-01

    A RF H-plasma exposure was used to clean the surface of Si-SiO2 patterned wafers. The areal coverage of SiO2 to bare Si was 4 to 1, and the patterns were long strips, small squares, and large open regions. The plasma-surface etching was monitored by residual gas analysis (RGA). The RGA spectra indicated etching of the Si surface at temperatures below 400 C and no detectable by-products due to interactions with the SiO2 regions for temperatures less than 450 C. The patterned surfaces were characterized with low energy electron diffraction (LEED) (from the bare Si regions) and atomic force microscopy (AFM). The LEED patterns indicate 1 x 1 and 2 x 1 surface symmetries at 300 and 450 C, respectively. The sharpness of the LEED patterns as well as the 2 x 1 reconstruction indicated that the H-plasma cleaned the bare Si regions. In addition, AFM measurements indicated that the Si and SiO2 surface rms roughnesses do not vary significantly due to the H-plasma exposure. It can be concluded from the RGA and AFM data that the remote H-plasma process at 450 C cleaned the surface and did not significantly react with either the Si or SiO2 regions.

  8. Scanning electron microscopic study of laser-induced morphologic changes of a coated enamel surface

    SciTech Connect

    Hess, J.A. )

    1990-01-01

    A low-energy Nd:YAG laser was used to irradiate extracted human teeth coated with a black energy-absorbent laser initiator in a study to determine the extent of the morphologic changes produced in the enamel surface. The laser initiator was applied to a cleaned enamel surface and irradiated at an energy output of 30 mJ or 75 mJ. Both energy levels produced morphologic changes of the surface. There was a sharp line of demarcation between the coated, irradiated area and the surrounding noncoated enamel surface. The scanning electron microscope view at the lower energy level showed that the surface had melted and reformed with numerous small, bubble-like inclusions. The 75 mJ energy level showed individual impact craters with shallow centers and raised edges containing numerous pores and large, bubble-like inclusions. Etching is a dental procedure in which an acid is normally used to remove a thin outer layer of the tooth structure. This is necessary to create a roughened, irregular surface in order to provide mechanical retention for dental restorative materials. The changes produced by the laser in this study suggest a simple, effective, and controlled method of etching the enamel surface of a tooth by altering its surface characteristics.

  9. Control of pyrite surface chemistry in physical coal cleaning

    SciTech Connect

    Yoon, R.H.; Richardson, P.R.

    1992-06-24

    One of the most difficult separations in minerals processing involves the differential flotation of pyrite and coal. Under practical flotation conditions, they are both hydrophobic and no cost-effective method has been developed to efficiently reject the pyrite. The problem arises from inherent floatability of coal and pyrite. Coal is naturally hydrophobic and remains so under practical flotation. Although pyrite is believed to be naturally hydrophilic under practical flotation conditions it undergoes a relatively rapid incipient oxidation reaction that causes self-induced'' flotation. The oxidation product responsible for self-induced'' flotation is believed to be a metal polysulfide, excess sulfur in the lattice, or in some cases elemental sulfur. It is believed that if incipient oxidation of pyrite could be prevented, good pyrite rejection could be obtained. In order to gain a better understanding of how pyrite oxidizes, a new method of preparing fresh, unoxidized pyrite surfaces and a new method of studying pyrite oxidation have been developed this reporting period.

  10. Laser Surface Engineering of Magnesium Alloys: A Review

    NASA Astrophysics Data System (ADS)

    Singh, Ashish; Harimkar, Sandip P.

    2012-06-01

    Magnesium (Mg) and its alloys are well known for their high specific strength and low density. However, widespread applications of Mg alloys in structural components are impeded by their insufficient wear and corrosion resistance. Various surface engineering approaches, including electrochemical processes (plating, conversion coatings, hydriding, and anodizing), gas-phase deposition (thermal spray, chemical vapor deposition, physical vapor deposition, diamond-like coatings, diffusion coatings, and ion implantation), and organic polymer coatings (painting and powder coating), have been used to improve the surface properties of Mg and its alloys. Recently, laser surface engineering approaches are attracting significant attention because of the wide range of possibilities in achieving the desired microstructural and compositional modifications through a range of laser-material interactions (surface melting, shock peening, and ablation). This article presents a review of various laser surface engineering approaches such as laser surface melting, laser surface alloying, laser surface cladding, laser composite surfacing, and laser shock peening used for surface modification of Mg alloys. The laser-material interactions, microstructural/compositional changes, and properties development (mostly corrosion and wear resistance) accompanied with each of these approaches are reviewed.

  11. Studying femtosecond-laser hyperdoping by controlling surface morphology

    SciTech Connect

    Winkler, Mark T.; Sher, Meng-Ju; Lin Yuting; Zhang, Haifei; Smith, Matthew J.; Gradecak, Silvija; Mazur, Eric

    2012-05-01

    We study the fundamental properties of femtosecond-laser (fs-laser) hyperdoping by developing techniques to control the surface morphology following laser irradiation. By decoupling the formation of surface roughness from the doping process, we study the structural and electronic properties of fs-laser doped silicon. These experiments are a necessary step toward developing predictive models of the doping process. We use a single fs-laser pulse to dope silicon with sulfur, enabling quantitative secondary ion mass spectrometry, transmission electron microscopy, and Hall effect measurements. These measurements indicate that at laser fluences at or above 4 kJ m{sup -2}, a single laser pulse yields a sulfur dose >(3 {+-} 1) x 10{sup 13} cm{sup -2} and results in a 45-nm thick amorphous surface layer. Based on these results, we demonstrate a method for hyperdoping large areas of silicon without producing the surface roughness.

  12. Interaction of D{sub 2}O with model oxide single crystal surfaces: Clean and oxidized W(110)

    SciTech Connect

    Herman, G.S.; Gallagher, M.C.; Joyce, S.

    1995-12-31

    It has been suggested that the interaction of D{sub 2}O with single crystal oxide surfaces are dominated by defects. To investigate this we have prepared and then characterized oxidized W(110) surfaces with Auger electron spectroscopy, low-energy electron diffraction, and scanning tunneling microscopy. We have also used temperature programmed desorption (TPD) to investigate the interaction of D{sub 2}O with these surfaces. Results indicate that desorption of D{sub 2}O occurs from two states for both the clean and fully oxidized surface. The decomposition of D{sub 2}O was found to occur on the clean surface but not for the fully oxidized surface. This is evident from the observation of residual oxygen remaining on the clean surface after a TPD cycle as well as the observation of two different D{sub 2} desorption features for the clean surface. On the fully oxidized surface neither occur.

  13. Microbial surface contamination after standard operating room cleaning practices following surgical treatment of infection.

    PubMed

    Balkissoon, Rishi; Nayfeh, Tariq; Adams, Kerri L; Belkoff, Stephen M; Riedel, Stefan; Mears, Simon C

    2014-04-01

    At the authors' institution, some joint arthroplasty surgeons require the operating room to be terminally cleaned before using the room after infected cases, in theory to decrease exposure to excessive microbial contamination for the subsequent patient. The authors found no guidance in the literature to support this practice. To test this theory, the authors measured microbial surface contamination from 9 surfaces in operating rooms after standard operating room turnover following 14 infected cases vs 16 noninfected cases. A check was made for an association between organisms isolated intraoperatively from infected surgical patients immediately preceding standard cleaning and organisms isolated from common operating room surfaces. Colony counts were made at 24 and 48 hours, and organisms were identified. No significant difference was noted in colony counts between infected and noninfected cases, and no relationship was found between organisms isolated from infected cases and those from operating room surfaces. Furthermore, the largest colony count from both groups (0.08 cfu/cm(2)) was an order of magnitude less than the recently proposed 5 cfu/cm(2) threshold for surface hygiene in hospitals. This finding indicates that standard operating room turnover results in minimal surface contamination, regardless of the previous case's infection status, and that there is no need for a more extensive terminal cleaning after an infected case.

  14. Ion neutralization as a probe to study electronic dynamics on clean and nanostructured surfaces

    NASA Astrophysics Data System (ADS)

    Lee, Hee Suk; O'Connell, Ryan; Schmitz, Andrew; Shaw, John; Chakraborty, Himadri

    2011-03-01

    Resonant charge transfer in ion-surface collisions is a classic tool to explore the surface electronic structure. Using the Crank-Nicholson propagation we solve the time-dependent Schroedinger equation to simulate electrons' motion during the interaction of a H- anion with clean, nanostepped, and nanolayered metal surfaces. Ion survival from a clean surface is found to depend adiabatically on the metal band gap, but for the fast (diabatic) ion-speed perpendicular to the surface interactions with image states dominate. For larger distance of ion's closest approach, however, the image interaction intrudes the adiabatic region. For the stepped surfaces, conversely, the survival is found to depend on the ion speed parallel to the surface from super-lattice sub-band effects, resulting in rich structures in the survival probability. Electrons that populate a nanolayered surface, in contrast, are found to modify the Shockley surface state and image states by inducing standing waves in the direction perpendicular to the surface. Supported by NSF and Applied Research NWMSU.

  15. Optical velocimeters for moving surfaces using gas and semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Belousov, P. Ya.; Dubnistshev, Yu. N.; Meledin, V. G.

    1990-10-01

    A differential arrangement using a laser for the measurement of the velocity of moving surfaces is discussed. Configurations of optical velocimeters with diffraction beam-splitters are shown not to be critical on the wavelength stability of a semiconductor laser. Laser meters measuring the velocity and length of rolled stock have been built on the basis of the devices considered.

  16. Behavior of the 222Rn daughters on copper surfaces during cleaning

    SciTech Connect

    Wojcik, Marcin; Zuzel, Grzegorz

    2007-03-28

    Removal of the long-living 222Rn daughters (210Pb, 210Bi and 210Po) from the copper surface has been investigated. Different methods, like chemical etching and electropolishing, were applied to discs exposed earlier to a strong radon source. A long exposure assured effective accumulation of the 222Rn progenies on the copper surface. Cleaning efficiency for 210Pb was tested using a HPGe spectrometer, for 210Bi a beta spectrometer and for 210Po an alpha spectrometer were used. According to the conducted measurements electropolishing removes very effectively all the isotopes, while etching works only for lead and bismuth, for polonium the cleaning effect is practically negligible. Most probable 210Po is re-deposited on the treated surface.

  17. Cleaning Hospital Room Surfaces to Prevent Health Care–Associated Infections

    PubMed Central

    Han, Jennifer H.; Sullivan, Nancy; Leas, Brian F.; Pegues, David A.; Kaczmarek, Janice L.; Umscheid, Craig A.

    2015-01-01

    The cleaning of hard surfaces in hospital rooms is critical for reducing health care–associated infections. This review describes the evidence examining current methods of cleaning, disinfecting, and monitoring cleanliness of patient rooms, as well as contextual factors that may affect implementation and effectiveness. Key informants were interviewed, and a systematic search for publications since 1990 was done with the use of several bibliographic and gray literature resources. Studies examining surface contamination, colonization, or infection with Clostridium difficile, methicillin-resistant Staphylococcus aureus, or vancomycinresistant enterococci were included. Eighty studies were identified—76 primary studies and 4 systematic reviews. Forty-nine studies examined cleaning methods, 14 evaluated monitoring strategies, and 17 addressed challenges or facilitators to implementation. Only 5 studies were randomized, controlled trials, and surface contamination was the most commonly assessed outcome. Comparative effectiveness studies of disinfecting methods and monitoring strategies were uncommon. Future research should evaluate and compare newly emerging strategies, such as self-disinfecting coatings for disinfecting and adenosine triphosphate and ultraviolet/fluorescent surface markers for monitoring. Studies should also assess patient-centered outcomes, such as infection, when possible. Other challenges include identifying high-touch surfaces that confer the greatest risk for pathogen transmission; developing standard thresholds for defining cleanliness; and using methods to adjust for confounders, such as hand hygiene, when examining the effect of disinfecting methods. PMID:26258903

  18. Cleaning Hospital Room Surfaces to Prevent Health Care-Associated Infections: A Technical Brief.

    PubMed

    Han, Jennifer H; Sullivan, Nancy; Leas, Brian F; Pegues, David A; Kaczmarek, Janice L; Umscheid, Craig A

    2015-10-20

    The cleaning of hard surfaces in hospital rooms is critical for reducing health care-associated infections. This review describes the evidence examining current methods of cleaning, disinfecting, and monitoring cleanliness of patient rooms, as well as contextual factors that may affect implementation and effectiveness. Key informants were interviewed, and a systematic search for publications since 1990 was done with the use of several bibliographic and gray literature resources. Studies examining surface contamination, colonization, or infection with Clostridium difficile, methicillin-resistant Staphylococcus aureus, or vancomycin-resistant enterococci were included. Eighty studies were identified-76 primary studies and 4 systematic reviews. Forty-nine studies examined cleaning methods, 14 evaluated monitoring strategies, and 17 addressed challenges or facilitators to implementation. Only 5 studies were randomized, controlled trials, and surface contamination was the most commonly assessed outcome. Comparative effectiveness studies of disinfecting methods and monitoring strategies were uncommon. Future research should evaluate and compare newly emerging strategies, such as self-disinfecting coatings for disinfecting and adenosine triphosphate and ultraviolet/fluorescent surface markers for monitoring. Studies should also assess patient-centered outcomes, such as infection, when possible. Other challenges include identifying high-touch surfaces that confer the greatest risk for pathogen transmission; developing standard thresholds for defining cleanliness; and using methods to adjust for confounders, such as hand hygiene, when examining the effect of disinfecting methods.

  19. Cleaning Hospital Room Surfaces to Prevent Health Care-Associated Infections: A Technical Brief.

    PubMed

    Han, Jennifer H; Sullivan, Nancy; Leas, Brian F; Pegues, David A; Kaczmarek, Janice L; Umscheid, Craig A

    2015-10-20

    The cleaning of hard surfaces in hospital rooms is critical for reducing health care-associated infections. This review describes the evidence examining current methods of cleaning, disinfecting, and monitoring cleanliness of patient rooms, as well as contextual factors that may affect implementation and effectiveness. Key informants were interviewed, and a systematic search for publications since 1990 was done with the use of several bibliographic and gray literature resources. Studies examining surface contamination, colonization, or infection with Clostridium difficile, methicillin-resistant Staphylococcus aureus, or vancomycin-resistant enterococci were included. Eighty studies were identified-76 primary studies and 4 systematic reviews. Forty-nine studies examined cleaning methods, 14 evaluated monitoring strategies, and 17 addressed challenges or facilitators to implementation. Only 5 studies were randomized, controlled trials, and surface contamination was the most commonly assessed outcome. Comparative effectiveness studies of disinfecting methods and monitoring strategies were uncommon. Future research should evaluate and compare newly emerging strategies, such as self-disinfecting coatings for disinfecting and adenosine triphosphate and ultraviolet/fluorescent surface markers for monitoring. Studies should also assess patient-centered outcomes, such as infection, when possible. Other challenges include identifying high-touch surfaces that confer the greatest risk for pathogen transmission; developing standard thresholds for defining cleanliness; and using methods to adjust for confounders, such as hand hygiene, when examining the effect of disinfecting methods. PMID:26258903

  20. Laser surface texturing for high friction contacts

    NASA Astrophysics Data System (ADS)

    Dunn, A.; Wlodarczyk, K. L.; Carstensen, J. V.; Hansen, E. B.; Gabzdyl, J.; Harrison, P. M.; Shephard, J. D.; Hand, D. P.

    2015-12-01

    A pulsed, nanosecond fibre laser with wavelength of 1064 nm was used to texture grade 316 stainless steel and 'low alloy' carbon steel in order to generate contacts with high static friction coefficients. High friction contacts have applications in reducing the tightening force required in joints or to easily secure precision fittings, particularly for larger components where standard methods are difficult and expensive. Friction tests performed at normal pressures of 100 MPa and 50 MPa have shown that very high static friction coefficients greater than 1.25, an increase of 346% over untextured samples at 100 MPa, can be easily achieved by single pass laser texturing of both contacting surfaces with the use of low pulse separations. The high static friction coefficients, obtained at 100 MPa normal pressure with textures with up to 62.5 μm pulse separation (processing speed ∼0.67 cm2/s), were found to be associated with a significant amount of plastic deformation caused by the high normal pressures. As a result, higher normal pressures were found to result in higher friction coefficients.

  1. Transparent self-cleaning lubricant-infused surfaces made with large-area breath figure patterns

    NASA Astrophysics Data System (ADS)

    Zhang, Pengfei; Chen, Huawei; Zhang, Liwen; Ran, Tong; Zhang, Deyuan

    2015-11-01

    Nepenthes pitcher inspired slippery lubricant-infused porous surfaces greatly impact the understanding of liquid-repellent surfaces construction and have attracted extensive attention in recent years due to their potential applications in self-cleaning, anti-fouling, anti-icing, etc. In this work, we have successfully fabricated transparent slippery lubricant-infused surfaces based on breath figure patterns (BFPs). Large-area BFPs with interconnected pores were initially formed on the glass substrate and then a suitable lubricant was added onto the surfaces. The interconnected pores in BFPs were able to hold the lubricant liquid in place and form a stable liquid/solid composite surface capable of repelling a variety of liquids. The liquid-repellent surfaces show extremely low critical sliding angles for various liquids, thus providing the surfaces with efficient self-cleaning property. It was also found that the liquid droplets' sliding behaviors on the surfaces were significantly influenced by the tilting angle of the substrate, liquid volume, liquid chemical properties, and pore sizes of the surfaces.

  2. Evolution of surface stress during oxygen exposure of clean Si(111), Si(100), and amorphous Si surfaces

    SciTech Connect

    Flötotto, D. Wang, Z. M.; Jeurgens, L. P. H.; Mittemeijer, E. J.

    2014-01-14

    The evolutions of the surface stress of Si(111)-7 × 7, Si(100)-2 × 1, and a-Si surfaces upon oxygen exposure at pO{sub 2} = 1 × 10{sup −4} Pa and room temperature have been investigated in a comparative manner using a specimen-curvature based technique. To this end, a generally applicable, dedicated set of experiments has been devised and performed to deduce and correct for the surface stress change owing to oxygen reaction(s) at the (poorly-defined) back face of the specimen only. On this basis, it could be demonstrated that exposure of clean Si(111)-7 × 7, Si(100)-2 × 1 and a-Si surfaces to pure oxygen gas results in compressive surface stress changes for all three surfaces due to the incorporation of oxygen into Si backbonds. The measured surface stress change decreases with decreasing atomic packing density at the clean Si surfaces, which complies well with the less-densily packed Si surface regions containing more free volume for the accommodation of adsorbed O atoms.

  3. Photonic crystal surface-emitting lasers

    SciTech Connect

    Chua, Song Liang; Lu, Ling; Soljacic, Marin

    2015-06-23

    A photonic-crystal surface-emitting laser (PCSEL) includes a gain medium electromagnetically coupled to a photonic crystal whose energy band structure exhibits a Dirac cone of linear dispersion at the center of the photonic crystal's Brillouin zone. This Dirac cone's vertex is called a Dirac point; because it is at the Brillouin zone center, it is called an accidental Dirac point. Tuning the photonic crystal's band structure (e.g., by changing the photonic crystal's dimensions or refractive index) to exhibit an accidental Dirac point increases the photonic crystal's mode spacing by orders of magnitudes and reduces or eliminates the photonic crystal's distributed in-plane feedback. Thus, the photonic crystal can act as a resonator that supports single-mode output from the PCSEL over a larger area than is possible with conventional PCSELs, which have quadratic band edge dispersion. Because output power generally scales with output area, this increase in output area results in higher possible output powers.

  4. Final Clean Closure Report Site 300 Surface Impoundments Closure Lawrence Livermore National Laboratory Livermore, California

    SciTech Connect

    Haskell, K

    2006-02-14

    Lawrence Livermore National Laboratory operated two Class II surface impoundments that stored wastewater that was discharged from a number of buildings located on the Site 300 Facility (Site 300). The wastewater was the by-product of explosives processing. Reduction in the volume of water discharged from these buildings over the past several years significantly reduced the wastewater storage needs. In addition, the impoundments were constructed in 1984, and the high-density polyethylene (HDPE) geomembrane liners were nearing the end of their service life. The purpose of this project was to clean close the surface impoundments and provide new wastewater storage using above ground storage tanks at six locations. The tanks were installed and put into service prior to closure of the impoundments. This Clean Closure Report (Closure Report) complies with State Water Resources Control Board (SWRCB) Section 21400 of the California Code of Regulations Title 27 (27 CCR section 21400). As required by these regulations and guidance, this Closure Report provides the following information: (1) a brief site description; (2) the regulatory requirements relevant to clean closure of the impoundments; (3) the closure procedures; and (4) the findings and documentation of clean closure.

  5. Nanosecond laser textured superhydrophobic metallic surfaces and their chemical sensing applications

    NASA Astrophysics Data System (ADS)

    Ta, Duong V.; Dunn, Andrew; Wasley, Thomas J.; Kay, Robert W.; Stringer, Jonathan; Smith, Patrick J.; Connaughton, Colm; Shephard, Jonathan D.

    2015-12-01

    This work demonstrates superhydrophobic behavior on nanosecond laser patterned copper and brass surfaces. Compared with ultrafast laser systems previously used for such texturing, infrared nanosecond fiber lasers offer a lower cost and more robust system combined with potentially much higher processing rates. The wettability of the textured surfaces develops from hydrophilicity to superhydrophobicity over time when exposed to ambient conditions. The change in the wetting property is attributed to the partial deoxidation of oxides on the surface induced during laser texturing. Textures exhibiting steady state contact angles of up to ∼152° with contact angle hysteresis of around 3-4° have been achieved. Interestingly, the superhydrobobic surfaces have the self-cleaning ability and have potential for chemical sensing applications. The principle of these novel chemical sensors is based on the change in contact angle with the concentration of methanol in a solution. To demonstrate the principle of operation of such a sensor, it is found that the contact angle of methanol solution on the superhydrophobic surfaces exponentially decays with increasing concentration. A significant reduction, of 128°, in contact angle on superhydrophobic brass is observed, which is one order of magnitude greater than that for the untreated surface (12°), when percent composition of methanol reaches to 28%.

  6. Biocompatibility Evaluation of Nanosecond Laser Treated Titanium Surfaces

    NASA Astrophysics Data System (ADS)

    Honda, Ryo; Mizutani, Masayoshi; Ohmori, Hitoshi; Komotori, Jun

    We developed surface modification technologies for dental implants in this study. The study contributes to shortening the time required for adhesion between alveolar bone and fixtures which consist of dental implants. A Nd:YVO4 nanosecond laser was used to modify the surfaces of commercially pure titanium (CP Ti) disks, and their biocompatibility was evaluated cytocompatibility and bioactivity. First, rows of 200 µm spaced rectilinear laser treatments were performed on surfaces of CP Ti disks. Osteoblasts derived from rat mesenchymal stem cells were then cultured on the treated surfaces. Cytocompatibility on the laser treated area was evaluated by observing adhesion behavior of cells on these surfaces. The results indicated that the micro-order structure formed by the laser treatment promoted adhesion of osteoblasts and that traces of laser treatment without microstucture didn't affect the adhesion. Second, surfaces of CP Ti disks were completely covered by traces of laser treatment, which created complex microstructures of titania whose crystal structure is rutile and anatase. This phenomenon allowed the creation of hydroxyapatite on the surface of the disks in 1.5-times simulated body fluid (1.5SBF) while no hydroxyapatite was observed on conventional polished surfaces in the same conditions. This result indicates that bioactivity was enabled on CP Ti by the laser treatment. From these two results, laser treatment for CP Ti surfaces is an effective method for enhancing adhesion of osteoblasts and promoting bioactivity, which are highly appreciated properties for dental implants.

  7. Surface cleaning and etching of rare-earth-doped phosphate glass

    NASA Astrophysics Data System (ADS)

    Barnes, Amy S.; Pantano, Carlo G.; Conzone, Samuel D.

    2001-11-01

    The surface reactions of phosphate glasses are important for the processing and application of photonic devices, biomedical materials and conventional optical components. Of particular concern are the leaching of optically-active dopant species, surface layer formation and roughening during polishing, cleaning and other fabrication processes. In this study, the effects of various cleaning treatments, and both acid and base etching, were evaluated using surface analytical techniques (XPS, AFM). It is shown that in these phosphate glasses, the aluminum and rare-earth oxides have limited aqueous solubility, whereas the phosphate network is soluble over a wider range of pH. Thus, under those conditions where polishing damage can be removed by etching the surface, a localized precipitation of rare-earth oxides occurs which influences the final roughness and surface composition. Conversely, under conditions where this precipitation can be eliminated, an in-depth leaching of the surface occurs. These aqueous surface reactions were similar for both the optically-active and passive IOG-1 glasses. An optimized surface preparation method is described.

  8. Laser buffing of nickel-phosphorous surface after mechanical texturing

    NASA Astrophysics Data System (ADS)

    Liu, Daming; Lu, Yongfeng; Neo, Y. Y.; Wang, Weijie; Low, Tohsiew

    1998-08-01

    Laser buffing of nickel-phosphorous (NiP) surface after mechanic texturing has been investigated. A KrF excimer laser ((lambda) equals 248 nm, (tau) equals 23 ns) was employed in the experiment as an irradiation source. The sample is a mechanic- textured hard disk. Atomic force microscope (AFM) was used to analyze the surface morphologies before and after laser irradiation. The results show that the surface was buffed in micro-scale after laser irradiation. The surface root mean square roughness and average roughness decreased. One- dimensional thermal conduction model was used to simulate the temperature distribution in the irradiated region. The mechanisms of laser buffing are proposed based on the investigation. It is more likely due to selectively localized melting during laser irradiation.

  9. Ultrafast oleophobic-hydrophilic switching surfaces for antifogging, self-cleaning, and oil-water separation.

    PubMed

    Brown, P S; Atkinson, O D L A; Badyal, J P S

    2014-05-28

    Smooth copolymer-fluorosurfactant complex film surfaces are found to exhibit fast oleophobic-hydrophilic switching behavior. Equilibration of the high oil contact angle (hexadecane = 80°) and low water contact angle (<10°) values occurs within 10 s of droplet impact. These optically transparent surfaces display excellent antifogging and self-cleaning properties. The magnitude of oleophobic-hydrophilic switching can be further enhanced by the incorporation of surface roughness to an extent that it reaches a sufficiently high level (water contact angle <10° and hexadecane contact angle >110°), which, when combined with the inherent ultrafast switching speed, yields oil-water mixture separation efficiencies exceeding 98%. PMID:24786299

  10. Ultrafast oleophobic-hydrophilic switching surfaces for antifogging, self-cleaning, and oil-water separation.

    PubMed

    Brown, P S; Atkinson, O D L A; Badyal, J P S

    2014-05-28

    Smooth copolymer-fluorosurfactant complex film surfaces are found to exhibit fast oleophobic-hydrophilic switching behavior. Equilibration of the high oil contact angle (hexadecane = 80°) and low water contact angle (<10°) values occurs within 10 s of droplet impact. These optically transparent surfaces display excellent antifogging and self-cleaning properties. The magnitude of oleophobic-hydrophilic switching can be further enhanced by the incorporation of surface roughness to an extent that it reaches a sufficiently high level (water contact angle <10° and hexadecane contact angle >110°), which, when combined with the inherent ultrafast switching speed, yields oil-water mixture separation efficiencies exceeding 98%.

  11. Application of KrCI excilamp for cleaning GaAs surfaces using atomic hydrogen

    NASA Astrophysics Data System (ADS)

    Tarasenko, Victor F.; Kagadei, Valerii A.; Lomaev, Mikhail I.; Panchenko, Alexei N.; Proskurovsky, Dmitrii I.

    1998-06-01

    Novel single block process facility including UV excilamp and sources of atomic hydrogen is described. Circular sealed-off KrCl* excilamp emitting two intensive bands at 195 and 222 nm was used. The source of atomic hydrogen on the base of reflecting Penning arc discharge was placed in line with the lamp. Semiconducting structures were treated in an expanding effusion jet of atomic hydrogen. The possibility to realize the process of cleaning GaAs surface under joint action of atomic hydrogen and UV radiation has been investigated. Effect of UV radiation on the rate of removing oxide layer is found at low temperature (18 - 100 degree(s)C). The mechanism providing an explanation for this event is suggested. The possibility to realize GaAs surface cleaning using successive performing the procedures of the surface treatment by atomic hydrogen, its oxidation with UV- stimulation and additional treatment by atomic hydrogen was also studied. The sources of atomic hydrogen and UV radiation developed allows to improve cleaning control and provides a way of producing the surface with specified properties.

  12. A study of the effectiveness of particulate cleaning protocols on intentionally contaminated niobium surfaces

    SciTech Connect

    Reece, Charles E.; Ciancio, Elizabeth J.; Keyes, Katharine A.; Yang, Dian

    2009-11-01

    Particulate contamination on the surface of SRF cavities limits their performance via the enhanced generation of field-emitted electrons. Considerable efforts are expended to actively clean and avoid such contamination on niobium surfaces. The protocols in active use have been developed via feedback from cavity testing. This approach has the risk of over-conservatively ratcheting an ever increasing complexity of methods tied to particular circumstances. A complementary and perhaps helpful approach is to quantitatively assess the effectiveness of candidate methods at removing intentional representative particulate contamination. Toward this end, we developed a standardized contamination protocol using water suspensions of Nb{sub 2}O{sub 5} and SS 316 powders applied to BCP’d surfaces of standardized niobium samples yielding particle densities of order 200 particles/mm{sup 2}. From these starting conditions, controlled application of high pressure water rinse, ultrasonic cleaning, or CO{sub 2} snow jet cleaning was applied and the resulting surfaces examined via SEM/scanning EDS with particle recognition software. Results of initial parametric variations of each will be reported.

  13. Assessment of green cleaning effectiveness on polychrome surfaces by MALDI-TOF mass spectrometry and microscopic imaging.

    PubMed

    Hrdlickova Kuckova, Stepanka; Crhova Krizkova, Michaela; Pereira, Catarina Luísa Cortes; Hynek, Radovan; Lavrova, Olga; Busani, Tito; Branco, Luis Cobra; Sandu, Irina Crina Anca

    2014-08-01

    This article proposes an innovative methodology which employs nondestructive techniques to assess the effectiveness of new formulations based on ionic liquids, as alternative solvents for enzymes (proteases), for the removal of proteinaceous materials from painted surfaces during restoration treatments. Ionic liquids (ILs), also known as "designer" solvents, because of their peculiar properties which can be adjusted by selecting different cation-anion combinations, are potentially green solvents due totheir low vapour pressure. In this study, two ionic liquids were selected: IL1 (1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4 ])) and IL2 (1-ethyl-3-methylimidazolium ethylsulphate ([EMIM][EtSO4 ])). New formulations were prepared with these ILs and two different proteases (E): one acid (E1-pepsin) and one alkaline (E2-obtained from Aspergillus sojae). These formulations were tested on tempera and oil mock-up samples, prepared in accordance with historically documented recipes, and covered with two different types of protein-based varnishes (egg white and isinglass-fish glue). A noninvasive multiscale imaging methodology was applied before and after the treatment to evaluate the cleaning's effectiveness. Different microscopic techniques-optical microscopy (OM) with visible and fluorescent light, scanning electron microscopy (SEM) and atomic force microscopy (AFM)-together with Matrix-Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS) were applied on areas cleaned with the new formulations (IL + E) and reference areas cleaned only with the commercial enzyme formulations (gels). MALDI-TOF proved particularly very useful for comparing the diversity and abundance of peptides released by using different enzymatic systems. Microsc. Res. Tech. 77:574-585, 2014. © 2014 Wiley Periodicals, Inc. PMID:24825619

  14. Laser Surface Preparation and Bonding of Aerospace Structural Composites

    NASA Technical Reports Server (NTRS)

    Belcher, Marcus A.; Wohl, Christopher J.; Connell, John W.

    2009-01-01

    A Nd:YAG laser was used to etch patterns conducive to adhesive bonding onto CFRP surfaces. These were compared to typical pre-bonding surface treatments including grit blasting, manual abrasion, and peel ply. Laser treated composites were then subjected to optical microscopy, contact angle measurements, and post-bonding mechanical testing.

  15. Removal of graffiti paintings from the Mansion de Mattis site in Corato (Bari), Italy: Laser deveiling or complete cleaning?

    NASA Astrophysics Data System (ADS)

    Daurelio, G.; Andriani, E. S.; Albanese, A.; Catalano, I. M.; Teseo, G.; Marano, D.

    2008-10-01

    Nowadays one the main problem of stone monuments conservation is not only the natural environment deterioration but the defaced, in particular esthetic, due to graffiti. This paper presents the different stages of the cleaning graffiti research: the laboratory study phase, in which the aims were to investigate the laser cleaning effect on substrate and testing user-friendly and efficient solutions for in situ application; the application phase in which the study results were applied in the restoration of Palazzo de Mattis facade. The graffiti cleaning were carried out by using a Q-Switch Nd:YAG laser source (λ=1064 nm with pulse duration, t=8 ns, f=2 to 20 Hz, energy per impulse up to 280 mJ) in dry, wet and Very wet modes adopting the Daurelio technique n.1 (blade spot laser). The Q-Switch Nd:Yag laser source has demonstrated to be the most suitable for a fully or, according to new restoring theory, "de veiling" graffiti ablation.

  16. A Bronze Age Pre-Historic Dolmen: Laser Cleaning Techniques of Paintings and Graffiti (The Bisceglie Dolmen Case Study)

    NASA Astrophysics Data System (ADS)

    Daurelio, G.

    The whole building was included and covered by an elliptical plan tumulus as reported for other similar monuments situated in the same territory of BISCEGLIE and GIOVINAZZO (in South of Italy). The monument was built by a community established in that area to mark their territory. It has a typical funerary character (funeral urn) and it was destined to the collective sepulture in the Middle Bronze Age, as indicated by the ceramic finds, accompanying the rich dead men, copper objects and ornaments, bones and amber recovered inside together with human rests. Degradation Mapping and Laser Cleaning with Photographs, during and after the process in-situ were carried out. Black incrustations and writings (by some different felt pens, marking pens, permanent black and colored ink pigments — fluorescent and no, as well as permanent text liner markings and spayed black paint) were cleaned by using a portable Nd:YAG Laser (λ 1.06 μm — 0.53 μm, in N-Mode and Q-Switch Mode, Laser pulse duration 150 μs or 6ns — f 1 to 10Hz — E max. 500 mJ per pulse in 1st harmonic and 200 mJ per pulse in 2nd harmonic). So, according to the different ink types three different laser cleaning techniques were used.

  17. Laser forming of a bowl shaped surface with a stationary laser beam

    NASA Astrophysics Data System (ADS)

    Chakraborty, Shitanshu Shekhar; More, Harshit; Nath, Ashish Kumar

    2016-02-01

    Despite a lot of research done in the field of laser forming, generation of a symmetric bowl shaped surface by this process is still a challenge mainly because only a portion of the sheet is momentarily deformed in this process, unlike conventional sheet metal forming like deep drawing where the entire blank undergoes forming simultaneously reducing asymmetry to a minimum. The motion of laser beam also makes the process asymmetric. To counter these limitations this work proposes a new approach for laser forming of a bowl shaped surface by irradiating the centre of a flat circular blank with a stationary laser beam. With high power lasers, power density sufficient for laser forming, can be availed at reasonably large spot sizes. This advantage is exploited in this technique. Effects of duration of laser irradiation and beam spot diameter on the amount of bending and asymmetry in the formed surface were investigated. Laser power was kept constant while varying irradiation time. While varying laser spot diameter laser power was chosen so as to keep the surface temperature nearly constant at just below melting. Experimental conditions promoted almost uniform heating through sheet thickness. The amount of bending increased with irradiation time and spot diameter. It was interesting to observe that blanks bent towards the laser beam for smaller laser beam diameters and the reverse happened for larger spot diameters (~10 times of the sheet thickness). Effect of spot diameter variation has been explained with the help of coupled thermal-structural finite element simulations.

  18. Crystallographic and morphological textures in laser surface modified alumina ceramic

    NASA Astrophysics Data System (ADS)

    Harimkar, Sandip P.; Dahotre, Narendra B.

    2006-07-01

    Laser surface modification is an advanced technique for improving the surface performance of alumina ceramics in refractory and abrasive machining applications. Surface performance is expected to be greatly influenced by the crystallographic and morphological textures of surface grains generated during rapid solidification associated with laser processing. In this study, an investigation of the evolution of crystallographic and morphological textures during laser surface modifications of alumina ceramic was carried out using a 4kW Nd:YAG laser with fluences in the range of 458-726J/cm2. In these regimes of laser surface processing, the formation of equilibrium α-alumina was found to be assisted by catalytic sites provided by the substrate. Microstructure evolution was explored in terms of the development of crystallographic and morphological (size and shape) textures of surface grains as a function of laser processing parameters. The interdependence of crystallographic and morphological textures of the surface grains is discussed within the framework of faceted growth model suggesting that the formation of crystal shapes is governed by the relative velocities of certain crystallographic facets. Also, the effect of thermal aspects of laser processing on the morphology of the surface grains is discussed from the viewpoint of existing solidification theories.

  19. Fast microstructuring of silica glasses surface by NIR laser radiation

    NASA Astrophysics Data System (ADS)

    Kostyuk, G. K.; Sergeev, M. M.; Zakoldaev, R. A.; Yakovlev, E. B.

    2015-05-01

    The glass surface microstructuring technology using laser radiation with NIR wavelength (λ=1.064 μm) was revealed in this work. Glass plates were placed on the cellular graphite surface. Focused laser radiation passed through the glass plate and interacted with cellular graphite. The radiation heated the graphite surface and thus the high temperature influenced the back side of the glass plate. After consecutive laser scans, having certain periods and interruptions of laser radiation, the microstructures with depth ~0.5 μm were formed. Besides, in this work we suggested the method to calculate optical characteristics of formed elements. It was experimentally shown that these microstructures could be used to form phase diffraction gratings (PDGs) and random phase plates (RPPs). We experimentally demonstrated the possibility of these elements being used as RPPs which are suitable for multimode laser radiation homogenization and as PDGs which are suitable for laser simultaneous processing of metal films.

  20. Laser ablation system, and method of decontaminating surfaces

    DOEpatents

    Ferguson, Russell L.; Edelson, Martin C.; Pang, Ho-ming

    1998-07-14

    A laser ablation system comprising a laser head providing a laser output; a flexible fiber optic cable optically coupled to the laser output and transmitting laser light; an output optics assembly including a nozzle through which laser light passes; an exhaust tube in communication with the nozzle; and a blower generating a vacuum on the exhaust tube. A method of decontaminating a surface comprising the following steps: providing an acousto-optic, Q-switched Nd:YAG laser light ablation system having a fiber optically coupled output optics assembly; and operating the laser light ablation system to produce an irradiance greater than 1.times.10.sup.7 W/cm.sup.2, and a pulse width between 80 and 170 ns.

  1. Surface-attached cells, biofilms and biocide susceptibility: implications for hospital cleaning and disinfection.

    PubMed

    Otter, J A; Vickery, K; Walker, J T; deLancey Pulcini, E; Stoodley, P; Goldenberg, S D; Salkeld, J A G; Chewins, J; Yezli, S; Edgeworth, J D

    2015-01-01

    Microbes tend to attach to available surfaces and readily form biofilms, which is problematic in healthcare settings. Biofilms are traditionally associated with wet or damp surfaces such as indwelling medical devices and tubing on medical equipment. However, microbes can survive for extended periods in a desiccated state on dry hospital surfaces, and biofilms have recently been discovered on dry hospital surfaces. Microbes attached to surfaces and in biofilms are less susceptible to biocides, antibiotics and physical stress. Thus, surface attachment and/or biofilm formation may explain how vegetative bacteria can survive on surfaces for weeks to months (or more), interfere with attempts to recover microbes through environmental sampling, and provide a mixed bacterial population for the horizontal transfer of resistance genes. The capacity of existing detergent formulations and disinfectants to disrupt biofilms may have an important and previously unrecognized role in determining their effectiveness in the field, which should be reflected in testing standards. There is a need for further research to elucidate the nature and physiology of microbes on dry hospital surfaces, specifically the prevalence and composition of biofilms. This will inform new approaches to hospital cleaning and disinfection, including novel surfaces that reduce microbial attachment and improve microbial detachment, and methods to augment the activity of biocides against surface-attached microbes such as bacteriophages and antimicrobial peptides. Future strategies to address environmental contamination on hospital surfaces should consider the presence of microbes attached to surfaces, including biofilms.

  2. The effect of cleaning substances on the surface of denture base material

    PubMed Central

    Žilinskas, Juozas; Junevičius, Jonas; Česaitis, Kęstutis; Junevičiūtė, Gabrielė

    2013-01-01

    Bakcground The aim of this study was to evaluate the effect of substances used for hygienic cleaning of dentures on the surface of the denture base material. Material/Methods Meliodent Heat Cure (Heraeus-Kulzer, Germany) heat-polymerized acrylic resin was used to produce plates with all the characteristics of removable denture bases (subsequently, “plates”). Oral-B Complete toothbrushes of various brush head types were fixed to a device that imitated tooth brushing movements; table salt and baking soda (frequently used by patients to improve tooth brushing results), toothpaste (“Colgate Total”), and water were also applied. Changes in plate surfaces were monitored by measuring surface reflection alterations on spectrometry. Measurements were conducted before the cleaning and at 2 and 6 hours after cleaning. Results No statistically significant differences were found between the 3 test series. All 3 plates used in the study underwent statistically significant (p<0.05changed) – the reflection became poorer. The plates were most affected by the medium-bristle toothbrush with baking soda – the total reflection reduction was 4.82±0.1%; among toothbrushes with toothpaste, the hard-type toothbrush had the greatest reflection-reducing effect – 4.6±0.05%, while the toothbrush with table salt inflicted the least damage (3.5 ± 0.16%) due to the presence of rounded crystals between the bristles and the resin surface. Toothbrushes with water had a uniform negative effect on the plate surface – 3.89±0.07%. Conclusions All substances used by the patients caused surface abrasion of the denture base material, which reduced the reflection; a hard toothbrush with toothpaste had the greatest abrasive effect, while soft toothbrushes inflicted the least damage. PMID:24326781

  3. Airborne benzene exposures from cleaning metal surfaces with small volumes of petroleum solvents.

    PubMed

    Hollins, Dana M; Kerger, Brent D; Unice, Kenneth M; Knutsen, Jeffrey S; Madl, Amy K; Sahmel, Jennifer E; Paustenbach, Dennis J

    2013-06-01

    Airborne benzene concentrations were measured in a room with controlled air exchange during surface cleaning with two petroleum-based solvents (a paint thinner and an engine degreaser). The solvents were spiked with benzene to obtain target concentrations of 0.001, 0.01, and 0.1% by volume in the liquid. Personal samples on the worker and area samples up to 1.8m away were collected over 12 events (n=84 samples) designed to examine variation in exposure with solvent type, cleaning method (rag wipe or spatula scrape), surface area cleaned, air exchange rate, solvent volume applied, and distance from the cleaned surface. Average task breathing zone concentrations of benzene represented by 18-32 min time-weighted averages were 0.01 ppm, 0.05 ppm, and 0.27 ppm, when the solvents contained approximately 0.003, 0.008, and 0.07% benzene. Solvent benzene concentration, volume applied, and distance from the handling activities had the greatest effect on airborne concentrations. The studied solvent products containing 0.07% benzene (spiked) did not exceed the current OSHA permissible exposure limit of 1 ppm (averaged over 8h) or the ACGIH Threshold Limit Value of 0.5 ppm, in any of the tested short-term exposure scenarios. These data suggest that, under these solvent use scenarios, petroleum-based solvent products produced in the United States after 1978 likely did not produce airborne benzene concentrations above those measured if the concentration was less than 0.1% benzene. PMID:23088855

  4. Airborne benzene exposures from cleaning metal surfaces with small volumes of petroleum solvents.

    PubMed

    Hollins, Dana M; Kerger, Brent D; Unice, Kenneth M; Knutsen, Jeffrey S; Madl, Amy K; Sahmel, Jennifer E; Paustenbach, Dennis J

    2013-06-01

    Airborne benzene concentrations were measured in a room with controlled air exchange during surface cleaning with two petroleum-based solvents (a paint thinner and an engine degreaser). The solvents were spiked with benzene to obtain target concentrations of 0.001, 0.01, and 0.1% by volume in the liquid. Personal samples on the worker and area samples up to 1.8m away were collected over 12 events (n=84 samples) designed to examine variation in exposure with solvent type, cleaning method (rag wipe or spatula scrape), surface area cleaned, air exchange rate, solvent volume applied, and distance from the cleaned surface. Average task breathing zone concentrations of benzene represented by 18-32 min time-weighted averages were 0.01 ppm, 0.05 ppm, and 0.27 ppm, when the solvents contained approximately 0.003, 0.008, and 0.07% benzene. Solvent benzene concentration, volume applied, and distance from the handling activities had the greatest effect on airborne concentrations. The studied solvent products containing 0.07% benzene (spiked) did not exceed the current OSHA permissible exposure limit of 1 ppm (averaged over 8h) or the ACGIH Threshold Limit Value of 0.5 ppm, in any of the tested short-term exposure scenarios. These data suggest that, under these solvent use scenarios, petroleum-based solvent products produced in the United States after 1978 likely did not produce airborne benzene concentrations above those measured if the concentration was less than 0.1% benzene.

  5. The use of high power lasers in surface modification

    NASA Astrophysics Data System (ADS)

    Vesely, Edward J., Jr.; Verma, Suresh K.

    Results obtained in two areas of surface modification using a high power laser are reviewed: phase transformation and compositional transformation. The phase transformation process takes advantage of a solid or liquid state phase change, by using selective heating and quenching attainable with a laser. An example of such heat treating is laser processing of selective areas of a steel part with an annealed or normalized structure to form a hard martensite structure in those areas. In the compositional transformation process, the surface is melted and combined with alloying elements to form a surface with a new chemistry. The new surface can have a composition close to (by laser alloying) or completely different from (by laser cladding) the base alloy.

  6. Comparison of materials used for cleaning equipment in retail food premises, and of two methods for the enumeration of bacteria on cleaned equipment and work surfaces.

    PubMed

    Gilbert, R J

    1970-06-01

    There is no official scheme for testing disinfectants and detergent/disinfectants for use in the retail food trade and few recommended procedures have been given for the cleaning of equipment with these agents. Therefore, field trials were carried out in a large self-service store. Comparisons were made of the various cleaning efficiencies, as determined by bacterial plate counts, of detergent and disinfectant solutions and machine cleaning oils applied with either clean cloths or disposable paper towels to items of equipment. The most satisfactory results were always obtained when anionic detergent (0.75% w/v) and hypochlorite (200 p.p.m. available chlorine) solutions were applied in a ;two-step' procedure.Tests were made to compare the calcium alginate swab-rinse and the agar sausage (Agaroid) techniques for the enumeration of bacteria on stainless steel, plastic, formica and wooden surfaces before and after a cleaning process. Although recovery rates were always greater by the swab-rinse technique, the agar sausage technique was considered to be a useful routine control method for surface sampling. PMID:4914087

  7. Laser coupling effects on structural material under different surface conditions

    NASA Astrophysics Data System (ADS)

    Feng, Guobing; Wei, Chenghua; Wu, Lixiong; Chen, Linzhu; Lin, Xinwei; Zhang, Jianmin; Ma, Zhiliang

    2013-05-01

    The laser coupling effect of material is a fundamental factor to influence laser interaction with matter. The coupling coefficient, which is the material absorptance of the input laser energy, depends on the surface conditions of materials, such as temperature, incident angle, surface airflow, oxidizing environment, and so on. To measure the laser coupling characteristics of materials, two typical online measuring apparatuses were developed in our laboratory. One is based on a conjugated hemi-ellipsoidal reflectometer, which is suitable to measure the laser coupling coefficients of different temperature in vacuum and air environments. The other is based on an integrating sphere and a simple airflow simulator, which can be applied to online measure the laser absorptance of materials subjected to surface airflow. The laser coupling effects on two types of structural materials, which are alloy steels and composite materials, are given in this paper. With the conjugated ellipsoidal reflectometer, the laser coupling effects on a typical alloy steel are investigated in different temperatures under the vacuum and air environment, and the experimental results are analyzed. According the results, metal oxidization plays a key role in the laser coupling enhancement effects. Especially, when the metal is subjected to high power laser irradiation in the high subsonic airflow, metal oxidization which is an exothermic reaction enhances the laser damage effect and the convective heat loss is negligible. Finally, the laser coupling effects on a typical composite material subjected to airflow are studied by using the integrating sphere with an airflow simulator, and the experimental results of laser absorptance during the laser ablation are presented.

  8. Quantum well, beam deflecting surface emitting lasers

    NASA Technical Reports Server (NTRS)

    Kim, Jae H. (Inventor)

    1992-01-01

    This invention relates to surface emitting semiconductor lasers (SELs), with integrated 45 deg. beam deflectors. A SEL is formed on a wafer including vertical mirrors and 45 deg. beam deflectors formed in grooves by tilted ion beam etching. A SEL is a lattice matched, or unstrained, AlGaAs/GaAs GRINSCH SQW SEL. An alternate embodiment is shown, in which a SEL is lattice mismatched, strained or pseudomorphic, or InGaAs/AlGaAs GRINSCH SQW SEL which emits radiation at a wavelength to which its substrate is transparent. Both SELs exhibit high output power, low threshold current density, and relatively high efficiency, and each are processing compatible with conventional large scale integration technology. Such SELs may be fabricated in large numbers from single wafers. The novel features of this invention include the use of tilted ion beam etching to form a pair of grooves each including vertical mirrors and 45 deg. beam deflectors. The embodiment provides substantial circuit design flexibility because radiation may be coupled both up and/or down through the substrate.

  9. Quantum well, beam deflecting surface emitting lasers

    NASA Astrophysics Data System (ADS)

    Kim, Jae H.

    1992-10-01

    This invention relates to surface emitting semiconductor lasers (SELs), with integrated 45 deg. beam deflectors. A SEL is formed on a wafer including vertical mirrors and 45 deg. beam deflectors formed in grooves by tilted ion beam etching. A SEL is a lattice matched, or unstrained, AlGaAs/GaAs GRINSCH SQW SEL. An alternate embodiment is shown, in which a SEL is lattice mismatched, strained or pseudomorphic, or InGaAs/AlGaAs GRINSCH SQW SEL which emits radiation at a wavelength to which its substrate is transparent. Both SELs exhibit high output power, low threshold current density, and relatively high efficiency, and each are processing compatible with conventional large scale integration technology. Such SELs may be fabricated in large numbers from single wafers. The novel features of this invention include the use of tilted ion beam etching to form a pair of grooves each including vertical mirrors and 45 deg. beam deflectors. The embodiment provides substantial circuit design flexibility because radiation may be coupled both up and/or down through the substrate.

  10. Quantum well, beam deflecting surface emitting lasers

    NASA Astrophysics Data System (ADS)

    Kim, Jae H.

    1991-06-01

    This invention relates to surface emitting semiconductor lasers (SELs), with integrated 45 deg. beam deflectors. A SEL is formed on a wafer including vertical mirrors and 45 deg. beam deflectors formed in grooves by tilted ion beam etching. A SEL is a lattice matched, or unstrained, AlGaAs/GaAs GRINSCH SQW SEL. An alternate embodiment is shown, in which a SEL is lattice mismatched, strained or pseudomorphic, or InGaAs/AlGaAs GRINSCH SQW SEL which emits radiation at a wavelength to which its substrate is transparent. Both SELs exhibit high output power, low threshold current density, and relatively high efficiency, and each are processing compatible with conventional large scale integration technology. Such SELs may be fabricated in large numbers from single wafers. The novel features of this invention include the use of tilted ion beam etching to form a pair of grooves each including vertical mirrors and 45 deg. beam deflectors. The embodiment provides substantial circuit design flexibility because radiation may be coupled both up and/or down through the substrate.

  11. Interaction of highly vibrationally excited molecules with clean metal surfaces. Final technical report

    SciTech Connect

    Wodtke, A.M.; Auerbach, D.J.

    1998-11-01

    The authors present results from a grant funded under the Department of Energy Office of Basic Energy Sciences. A collaboration between Prof. Alec Wodtke of the Department of Chemistry at UCSB and Daniel J. Auerbach of IBM Almaden Research Labs has allowed new experiments on the dynamics of surface chemical reactivity to be successfully executed. High quality data has been generated which provides an excellent test of theoretical models of surface reactivity, a topic of importance to catalysis. The authors have obtained the first experimental measurements on the influence of reactant velocity on the steric effect in a chemical reaction: the dissociative adsorption of hydrogen on copper. They have also designed and built a molecular beam scattering apparatus for the study of highly vibrationally excited molecules and their interactions with clean and oxidized metal surfaces. With this apparatus they have observed the vibrational energy exchange of highly vibrationally excited NO with an oxidized copper surface. Multi-quantum vibrational relaxation was found ({Delta}v = 1-5). Such remarkably strong and efficient vibrational energy transfer represents a qualitatively new phenomenon and is representative of the exciting new behavior that they had hoped might be observable in this project. Evidence of chemical reactivity of vibrationally excited NO on a clean copper surface was also found.

  12. How do we assess hospital cleaning? A proposal for microbiological standards for surface hygiene in hospitals.

    PubMed

    Dancer, S J

    2004-01-01

    Increasing numbers of hospital-acquired infections have generated much attention over the last decade. The public has linked the so-called 'superbugs' with their experience of dirty hospitals, but the precise role of cleaning in the control of these organisms in unknown. Hence the importance of a clean environment is likely to remain speculative unless it becomes an evidence-based science. This proposal is a call for bacteriological standards with which to assess clinical surface hygiene in hospitals, based on those used by the food industry. The first standard concerns any finding of a specific 'indicator' organism, the presence of which suggests a requirement for increased cleaning. Indicators would include Staphylococcus aureus, including methicillin-resistant S. aureus, Clostridium difficile, vancomycin-resistant enterococci and various Gram-negative bacilli. The second standard concerns a quantitative aerobic colony count of <5 cfu/cm(2) on frequent hand touch surfaces in hospitals. The principle relates to modern risk management systems such as HACCP, and reflects the fact that pathogens of concern are widespread. Further work is required to evaluate and refine these standards and define the infection risk from the hospital environment.

  13. Surface composition analysis of HF vapour cleaned silicon by X-ray photoelectron spectroscopy

    NASA Astrophysics Data System (ADS)

    Ermolieff, A.; Martin, F.; Amouroux, A.; Marthon, S.; Westendorp, J. F. M.

    1991-06-01

    X-ray photoelectron spectroscopy (XPS) measurements on silicon surfaces treated by HF gaseous cleaning are described. Various cleaning recipes, which essentially differ by the amount of water present during the reaction were studied; the composition of the silicon surface was measured in terms of monolayer coverage of oxygen, fluorine and carbon. These gaseous cleaned surfaces are compared with those of commonly deglazed silicon samples by using an aqueous HF bath. The F(1s), O(1s), Si(2p), C(1s) photoelectron lines were monitored, and concentrations determined as usual by integration of the lines after removal of the non-linear backgroune. The F(1s), C(1s) and Si(2p) lines were decomposed into several components corresponding to different chemical bonds. The results show that the amount of fluorine is directly correlated with the amount of oxygen: the higher the oxygen level on the sample, the more important is the fluorine content till 0.7 ML, essentially in a O sbnd Si sbnd F bonding state. For more aggresive etching leaving less than one monolayer of oxygen, the Si sbnd F bond becomes predominant. The ratio of the SiF to OSiF concentrations is a significant signature of the deoxidation state of the surface. Hydrophobicity of the water appears in the range of 25% Si sbnd F bonds. With very aggresive etching processes, 67% Si sbnd F bonds and 33% O sbnd Si sbnd F bonds are reached and the total amount of fluoride drops below 0.3 ML. For comparison, only Si sbnd F bonds are observed after a wet etching in a dilute HF bath without a rinse with a much lower fluorine concentration. The balance between Si sbnd F and O sbnd Si sbnd F remains stable and seems to be representative of the surface states provided by the etching process.

  14. Surface cleaning of metals in air with a one atmosphere uniform glow discharge plasma

    SciTech Connect

    Roth, J.R.; Ku, Y.

    1995-12-31

    The authors report the use of active species generated in a one atmosphere uniform glow discharge plasma reactor with a parallel-plate configuration to clean the surface of as-received metal samples from the machine shop floor. The experimental arrangement used to expose the 7 by 10 cm metal samples is shown. The lower parallel-plate electrode is a flat copper plate 22 by 22 cm, covered by a 5mm thick pyrex sheet. The upper electrode is formed by the bare metal sample plate, with the side to be cleaned facing the plasma. To assure plasma uniformity between the electrodes, it was helpful to direct a flow of air on the edges of the plasma volume. The cleanliness of the metal samples was determined with the standard sessile water drop test.

  15. Laser-Induced Surface Damage of Optical Materials: Absorption Sources, Initiation, Growth, adn Mitigation

    SciTech Connect

    Papernov, S.; Schmid, A.W.

    2009-04-07

    Susceptibility to laser damage of optical-material surfaces originates from the nature of the surface as a transitional structure between optical-material bulk and its surroundings. As such, it requires technological processing to satisfy figure and roughness requirements and is also permanently subjected to environmental exposure. Consequently, enhanced absorption caused by mechanical structural damage or incorporation and sorption of microscale absorbing defects, even layers of organic materials, is always characteristic for optical-material surfaces. In this review physics of interaction of pulsed-laser radiation with surface imperfections for different types of optical materials (metals, semiconductors, dielectrics, etc.), mechanisms of damage initiation, damage morphology, and damage-site growth under repetitive pulse irradiation are discussed. Consideration is also given here to the surface treatments leading to the reduction of damage initiation sites, such as laser cleaning and conditioning, removal of the surface layers affected by the grinding/polishing process, and mitigation of the damage growth at already formed damage sites.

  16. Laser surface and subsurface modification of sapphire using femtosecond pulses

    NASA Astrophysics Data System (ADS)

    Eberle, G.; Schmidt, M.; Pude, F.; Wegener, K.

    2016-08-01

    Two methods to process sapphire using femtosecond laser pulses are demonstrated, namely ablation (surface), and in-volume laser modification followed by wet etching (subsurface). Firstly, the single and multipulse ablation threshold is determined and compared with previous literature results. A unique application of ablation is demonstrated by modifying the entrance aperture of water jet orifices. Laser ablation exhibits advantages in terms of geometric flexibility and resolution, however, defects in the form of edge outbreaks and poor surface quality are evident. Secondly, the role of material transformation, polarisation state and formation of multi-focus structures after in-volume laser modification is investigated in order to explain their influence during the wet etching process. Laser scanning and electron microscopy as well as electron backscatter diffraction measurements supported by ion beam polishing are used to better understand quality and laser-material interactions of the two demonstrated methods of processing.

  17. Predicting threshold and location of laser damage on optical surfaces

    DOEpatents

    Siekhaus, Wigbert

    1987-01-01

    An apparatus useful in the prediction of the damage threshold of various optical devices, the location of weak spots on such devices and the location, identification, and elimination of optical surface impurities comprising, a focused and pulsed laser, an photo electric detector/imaging means, and a timer. The weak spots emit photoelectrons when subjected to laser intensities that are less than the intensity actually required to produce the damage. The weak spots may be eliminated by sustained exposure to the laser beam.

  18. Laser Nanostructurization of the Metal and Alloy Surfaces

    NASA Astrophysics Data System (ADS)

    Kanavin, Andrei; Kozlovskaya, Natalia; Krokhin, Oleg; Zavestovskaya, Irina

    2010-10-01

    The results from experimental and theoretical investigation of material pulsed laser treatment aimed at obtaining nano- and microstructured surface are presented. An experiment has been performed on the modification of indium surface using a solid-state diode-pumped laser. It has been shown that nano- and micro-size structures are formed under laser melting and fast crystallization of the metal surface. The kinetics of the crystallization of metals under superfast cooling. The distribution function for crystalline nuclei dimensions is analytically found within the framework of the classical kinetic equation in case of superfast temperature changing. The average number of particles in the crystalline nuclei and relative volume of the crystalline phase are determined as functions of thermodynamic and laser treatment regime parameters. Good agreement is observed with experimental results for ultrashort laser pulses induced micro- and nanostructures production.

  19. Transparent, self-cleaning and waterproof surfaces with tunable micro/nano dual-scale structures.

    PubMed

    Lee, Yujin; You, Eun-Ah; Ha, Young-Geun

    2016-09-01

    The rational design and facile fabrication of optically transparent, superhydrophobic surfaces can advance their versatile applications, including optoelectronic devices. For the easily accessible and scalable preparation of transparent, superhydrophobic surfaces, various coating methods using a solution-process have been developed. However, obtaining highly transparent, non-wetting surfaces with excellent properties is challenging due to the difficulty in controlling surface roughness. Here, we report on a novel approach to control the surface roughness by fabricating tailorable micro/nano dual-scale surface structures via solution-processed nanoparticle coating. The surface roughness was able to be controlled by micro/nano dual-scale structures that can be manipulated by varying the mixture ratio of two different sizes of Al2O3 nanoparticles. The controllable micro/nano dual-scale structures were optimized to achieve the superior surface properties in both hydrophobicity and transparency, exhibiting a high water contact angle (>160°), low sliding angle (<2°) and high transmittance (>90%). These characteristics allowed an excellent transparency and self-cleaning capability as well as a superior waterproof ability even under applied voltage. Furthermore, we demonstrated the versatile applicability of the developed surface-coating method to a wide range of substrates including glass, paper, fabrics, and even flexible plastics. PMID:27454653

  20. Transparent, self-cleaning and waterproof surfaces with tunable micro/nano dual-scale structures.

    PubMed

    Lee, Yujin; You, Eun-Ah; Ha, Young-Geun

    2016-09-01

    The rational design and facile fabrication of optically transparent, superhydrophobic surfaces can advance their versatile applications, including optoelectronic devices. For the easily accessible and scalable preparation of transparent, superhydrophobic surfaces, various coating methods using a solution-process have been developed. However, obtaining highly transparent, non-wetting surfaces with excellent properties is challenging due to the difficulty in controlling surface roughness. Here, we report on a novel approach to control the surface roughness by fabricating tailorable micro/nano dual-scale surface structures via solution-processed nanoparticle coating. The surface roughness was able to be controlled by micro/nano dual-scale structures that can be manipulated by varying the mixture ratio of two different sizes of Al2O3 nanoparticles. The controllable micro/nano dual-scale structures were optimized to achieve the superior surface properties in both hydrophobicity and transparency, exhibiting a high water contact angle (>160°), low sliding angle (<2°) and high transmittance (>90%). These characteristics allowed an excellent transparency and self-cleaning capability as well as a superior waterproof ability even under applied voltage. Furthermore, we demonstrated the versatile applicability of the developed surface-coating method to a wide range of substrates including glass, paper, fabrics, and even flexible plastics.

  1. Transparent, self-cleaning and waterproof surfaces with tunable micro/nano dual-scale structures

    NASA Astrophysics Data System (ADS)

    Lee, Yujin; You, Eun-Ah; Ha, Young-Geun

    2016-09-01

    The rational design and facile fabrication of optically transparent, superhydrophobic surfaces can advance their versatile applications, including optoelectronic devices. For the easily accessible and scalable preparation of transparent, superhydrophobic surfaces, various coating methods using a solution-process have been developed. However, obtaining highly transparent, non-wetting surfaces with excellent properties is challenging due to the difficulty in controlling surface roughness. Here, we report on a novel approach to control the surface roughness by fabricating tailorable micro/nano dual-scale surface structures via solution-processed nanoparticle coating. The surface roughness was able to be controlled by micro/nano dual-scale structures that can be manipulated by varying the mixture ratio of two different sizes of Al2O3 nanoparticles. The controllable micro/nano dual-scale structures were optimized to achieve the superior surface properties in both hydrophobicity and transparency, exhibiting a high water contact angle (>160°), low sliding angle (<2°) and high transmittance (>90%). These characteristics allowed an excellent transparency and self-cleaning capability as well as a superior waterproof ability even under applied voltage. Furthermore, we demonstrated the versatile applicability of the developed surface-coating method to a wide range of substrates including glass, paper, fabrics, and even flexible plastics.

  2. Surface Modification of ICF Target Capsules by Pulsed Laser Ablation

    DOE PAGES

    Carlson, Lane C.; Johnson, Michael A.; Bunn, Thomas L.

    2016-06-30

    Topographical modifications of spherical surfaces are imprinted on National Ignition Facility (NIF) target capsules by extending the capabilities of a recently developed full surface (4π) laser ablation and mapping apparatus. The laser ablation method combines the precision, energy density and long reach of a focused laser beam to pre-impose sinusoidal modulations on the outside surface of High Density Carbon (HDC) capsules and the inside surface of Glow Discharge Polymer (GDP) capsules. Sinusoidal modulations described in this paper have sub-micron to 10’s of microns vertical scale and wavelengths as small as 30 μm and as large as 200 μm. The modulatedmore » patterns are created by rastering a focused laser fired at discrete capsule surface locations for a specified number of pulses. The computer program developed to create these raster patterns uses inputs such as laser beam intensity profile, the material removal function, the starting surface figure and the desired surface figure. The patterns are optimized to minimize surface roughness. Lastly, in this paper, simulated surfaces are compared with actual ablated surfaces measured using confocal microscopy.« less

  3. Femtosecond laser color marking of metal and semiconductor surfaces

    NASA Astrophysics Data System (ADS)

    Ionin, Andrey A.; Kudryashov, Sergey I.; Makarov, Sergey V.; Seleznev, Leonid V.; Sinitsyn, Dmitry V.; Golosov, Evgeniy V.; Golosova, Ol'ga A.; Kolobov, Yuriy R.; Ligachev, Alexander E.

    2012-05-01

    Color marking of rough or smooth metal (Al, Cu, Ti) and semiconductor (Si) surfaces was realized via femtosecond laser fabrication of periodic surface nanorelief, representing one-dimensional diffraction gratings. Bright colors of the surface nanorelief, especially for longer electromagnetic wavelengths, were provided during marking through pre-determined variation of the laser incidence angle and the resulting change of the diffraction grating period. This coloration technique was demonstrated for the case of silicon and various metals to mark surfaces in any individual color with a controllable brightness level and almost without their accompanying chemical surface modification.

  4. Robust authentication through stochastic femtosecond laser filament induced scattering surfaces

    NASA Astrophysics Data System (ADS)

    Zhang, Haisu; Tzortzakis, Stelios

    2016-05-01

    We demonstrate a reliable authentication method by femtosecond laser filament induced scattering surfaces. The stochastic nonlinear laser fabrication nature results in unique authentication robust properties. This work provides a simple and viable solution for practical applications in product authentication, while also opens the way for incorporating such elements in transparent media and coupling those in integrated optical circuits.

  5. Direct modification of silicon surface by nanosecond laser interference lithography

    NASA Astrophysics Data System (ADS)

    Wang, Dapeng; Wang, Zuobin; Zhang, Ziang; Yue, Yong; Li, Dayou; Maple, Carsten

    2013-10-01

    Periodic and quasi-periodic structures on silicon surface have numerous significant applications in photoelectronics and surface engineering. A number of technologies have been developed to fabricate the structures in various research fields. In this work, we take the strategy of direct nanosecond laser interference lithography technology, and focus on the silicon material to create different well-defined surface structures based on theoretical analysis of the formation of laser interference patterns. Two, three and four-beam laser interference systems were set up to fabricate the grating, regular triangle and square structures on silicon surfaces, respectively. From the AFM micrographs, the critical features of structures have a dependence on laser fluences. For a relative low laser fluence, grating and dot structures formed with bumps due to the Marangoni Effect. With the increase of laser fluences, melt and evaporation behaviors can be responsible for the laser modification. By properly selecting the process parameters, well-defined grating and dot structures can been achieved. It can be demonstrated that direct laser interference lithography is a facile and efficient technology with the advantage of a single process procedure over macroscale areas for the fabrication of micro and nano structures.

  6. Modern technologies for improving cleaning and disinfection of environmental surfaces in hospitals.

    PubMed

    Boyce, John M

    2016-01-01

    Experts agree that careful cleaning and disinfection of environmental surfaces are essential elements of effective infection prevention programs. However, traditional manual cleaning and disinfection practices in hospitals are often suboptimal. This is often due in part to a variety of personnel issues that many Environmental Services departments encounter. Failure to follow manufacturer's recommendations for disinfectant use and lack of antimicrobial activity of some disinfectants against healthcare-associated pathogens may also affect the efficacy of disinfection practices. Improved hydrogen peroxide-based liquid surface disinfectants and a combination product containing peracetic acid and hydrogen peroxide are effective alternatives to disinfectants currently in widespread use, and electrolyzed water (hypochlorous acid) and cold atmospheric pressure plasma show potential for use in hospitals. Creating "self-disinfecting" surfaces by coating medical equipment with metals such as copper or silver, or applying liquid compounds that have persistent antimicrobial activity surfaces are additional strategies that require further investigation. Newer "no-touch" (automated) decontamination technologies include aerosol and vaporized hydrogen peroxide, mobile devices that emit continuous ultraviolet (UV-C) light, a pulsed-xenon UV light system, and use of high-intensity narrow-spectrum (405 nm) light. These "no-touch" technologies have been shown to reduce bacterial contamination of surfaces. A micro-condensation hydrogen peroxide system has been associated in multiple studies with reductions in healthcare-associated colonization or infection, while there is more limited evidence of infection reduction by the pulsed-xenon system. A recently completed prospective, randomized controlled trial of continuous UV-C light should help determine the extent to which this technology can reduce healthcare-associated colonization and infections. In conclusion, continued efforts to

  7. Clean boiler systems chemically

    SciTech Connect

    Robinson, J.O. )

    1993-04-01

    Internal surfaces of steam generator systems are cleaned to remove contaminants that impair heat transfer and may ultimately cause tube failure. One method of doing so is chemical cleaning. All new steam generators should be chemically cleaned to remove construction contaminants. The degree of cleaning required depends on the initial condition of the boiler and on its operating requirements. This paper discusses: key considerations; pre-operational cleaning; post-operational cleaning; water flushing and steam blowing; alkaline cleaning; and solvent cleaning.

  8. Numerical Study of High-Speed Droplet Impact on Surfaces and its Physical Cleaning Effects

    NASA Astrophysics Data System (ADS)

    Kondo, Tomoki; Ando, Keita

    2015-11-01

    Spurred by the demand for cleaning techniques of low environmental impact, one favors physical cleaning that does not rely on any chemicals. One of the promising candidates is based on water jets that often involve fission into droplet fragments and collide with target surfaces to which contaminant particles (often micron-sized or even smaller) stick. Hydrodynamic force (e.g., shearing and lifting) arising from the droplet impact will play a role to remove the particles, but its detailed mechanism is still unknown. To explore the role of high-speed droplet impact in physical cleaning, we solve compressible Navier-Stokes equations with a finite volume method that is designed to capture both shocks and material interfaces in accurate and robust manners. Water hammer and shear flow accompanied by high-speed droplet impact at a rigid wall is simulated to evaluate lifting force and rotating torque, which are relevant to the application of particle removal. For the simulation, we use the numerical code recently developed by Computational Flow Group lead by Tim Colonius at Caltech. The first author thanks Jomela Meng for her help in handling the code during his stay at Caltech.

  9. Dermatopharmacokinetics of betamethasone 17-valerate: influence of formulation viscosity and skin surface cleaning procedure.

    PubMed

    Wiedersberg, Sandra; Leopold, Claudia S; Guy, Richard H

    2009-02-01

    The objective was to compare the in vivo distribution profiles of betamethasone 17-valerate (BMV) across the stratum corneum (SC) following (a) delivery from gelled and un-gelled formulations, and (b) two different skin cleaning procedures at the end of the application period. BMV was dissolved in gelled and un-gelled vehicles comprising either medium chain triglycerides (MCT) or a brand microemulsion (ME). The BMV concentration was adjusted to 80% of saturation and applied to the forearms of healthy volunteers. After 2 h, the treated skin site was cleaned either with a dry paper towel or with an isopropyl alcohol swab, and the SC was then progressively removed by repeated adhesive tape-stripping. BMV distribution profiles across the SC showed reasonable reproducibility, and that delivery from the ME was significantly superior to that from MCT. Gelled vehicles were less efficiently removed from the skin surface by dry wiping than un-gelled formulations. Removing excess formulation more aggressively with isopropyl alcohol resulted in a lower apparent uptake of drug into the SC. Excess gelled formulation may be trapped in the skin 'furrows', and requires an efficient skin cleaning procedure to ensure its complete removal. PMID:18940255

  10. Active optical system for advanced 3D surface structuring by laser remelting

    NASA Astrophysics Data System (ADS)

    Pütsch, O.; Temmler, A.; Stollenwerk, J.; Willenborg, E.; Loosen, P.

    2015-03-01

    Structuring by laser remelting enables completely new possibilities for designing surfaces since material is redistributed but not wasted. In addition to technological advantages, cost and time benefits yield from shortened process times, the avoidance of harmful chemicals and the elimination of subsequent finishing steps such as cleaning and polishing. The functional principle requires a completely new optical machine technology that maintains the spatial and temporal superposition and manipulation of three different laser beams emitted from two laser sources of different wavelength. The optical system has already been developed and demonstrated for the processing of flat samples of hot and cold working steel. However, since particularly the structuring of 3D-injection molds represents an application example of high innovation potential, the optical system has to take into account the elliptical beam geometry that occurs when the laser beams irradiate a curved surface. To take full advantage of structuring by remelting for the processing of 3D surfaces, additional optical functionality, called EPS (elliptical pre-shaping) has to be integrated into the existing set-up. The development of the beam shaping devices not only requires the analysis of the mechanisms of the beam projection but also a suitable optical design. Both aspects are discussed in this paper.

  11. Atomic diffusion in laser surface modified AISI H13 steel

    NASA Astrophysics Data System (ADS)

    Aqida, S. N.; Brabazon, D.; Naher, S.

    2013-07-01

    This paper presents a laser surface modification process of AISI H13 steel using 0.09 and 0.4 mm of laser spot sizes with an aim to increase surface hardness and investigate elements diffusion in laser modified surface. A Rofin DC-015 diffusion-cooled CO2 slab laser was used to process AISI H13 steel samples. Samples of 10 mm diameter were sectioned to 100 mm length in order to process a predefined circumferential area. The parameters selected for examination were laser peak power, pulse repetition frequency (PRF), and overlap percentage. The hardness properties were tested at 981 mN force. Metallographic study and energy dispersive X-ray spectroscopy (EDXS) were performed to observe presence of elements and their distribution in the sample surface. Maximum hardness achieved in the modified surface was 1017 HV0.1. Change of elements composition in the modified layer region was detected in the laser modified samples. Diffusion possibly occurred for C, Cr, Cu, Ni, and S elements. The potential found for increase in surface hardness represents an important method to sustain tooling life. The EDXS findings signify understanding of processing parameters effect on the modified surface composition.

  12. Surface Cleaning Techniques: Ultra-Trace ICP-MS Sample Preparation and Assay of HDPE

    SciTech Connect

    Overman, Nicole R.; Hoppe, Eric W.; Addleman, Raymond S.

    2013-06-01

    The world’s most sensitive radiation detection and assay systems depend upon ultra-low background (ULB) materials to reduce unwanted radiological backgrounds. Herein, we evaluate methods to clean HDPE, a material of interest to ULB systems and the means to provide rapid assay of surface and bulk contamination. ULB level material and ultra-trace level detection of actinide elements is difficult to attain, due to the introduction of contamination from sample preparation equipment such as pipette tips, sample vials, forceps, etc. and airborne particulate. To date, literature available on the cleaning of such polymeric materials and equipment for ULB applications and ultra-trace analyses is limited. For these reasons, a study has been performed to identify an effective way to remove surface contamination from polymers in an effort to provide improved instrumental detection limits. Inductively Coupled Plasma Mass Spectroscopy (ICP-MS) was utilized to assess the effectiveness of a variety of leachate solutions for removal of inorganic uranium and thorium surface contamination from polymers, specifically high density polyethylene (HDPE). HDPE leaching procedures were tested to optimize contaminant removal of thorium and uranium. Calibration curves for thorium and uranium ranged from 15 ppq (fg/mL) to 1 ppt (pg/mL). Detection limits were calculated at 6 ppq for uranium and 7 ppq for thorium. Results showed the most effective leaching reagent to be clean 6 M nitric acid for 72 hour exposures. Contamination levels for uranium and thorium found in the leachate solutions were significant for ultralow level radiation detection applications.

  13. Scattering of hyperthermal argon atoms from clean and D-covered Ru(0001) surfaces.

    PubMed

    Ueta, Hirokazu; Gleeson, Michael A; Kleyn, Aart W

    2011-01-21

    Hyperthermal Ar atoms were scattered from a Ru(0001) surface held at temperatures of 180, 400 and 600 K, and from a Ru(0001)-(1×1)D surface held at 114 and 180 K. The resultant angular intensity and energy distributions are complex. The in-plane angular distributions have narrow (FWHM ≤ 10°) near-specular peaks and additional off-specular features. The energy distributions show an oscillatory behavior as a function of outgoing angle. In comparison, scattered Ar atoms from a Ag(111) surface exhibit a broad angular intensity distribution and an energy distribution that qualitatively tracks the binary collision model. The features observed for Ru, which are most evident when scattering from the clean surface at 180 K and from the Ru(0001)-(1×1)D surface, are consistent with rainbow scattering. The measured TOF profiles cannot be adequately described with a single shifted Maxwell-Boltzmann distribution. They can be fitted by two components that exhibit complex variations as a function of outgoing angle. This suggests at least two significantly different site and∕or trajectory dependent energy loss processes at the surface. The results are interpreted in terms of the stiffness of the surface and highlight the anomalous nature of the apparently simple hcp(0001) ruthenium surface.

  14. Evaluation of surface sampling for Bacillus spores using commercially available cleaning robots.

    PubMed

    Lee, Sang Don; Calfee, M Worth; Mickelsen, Leroy; Wolfe, Stephen; Griffin, Jayson; Clayton, Matt; Griffin-Gatchalian, Nicole; Touati, Abderrahmane

    2013-03-19

    Five commercially available domestic cleaning robots were evaluated on their effectiveness for sampling aerosol-deposited Bacillus atrophaeus spores on different indoor material surfaces. The five robots tested include three vacuum types (R1, R2, and R3), one wet wipe (R4), and one wet vacuum (R5). Tests were conducted on two different surface types (carpet and laminate) with 10(6) colony forming units of B. atrophaeus spores deposited per coupon (35.5 cm × 35.5 cm). Spores were deposited on the center surface (30.5 × 30.5 cm) of the coupon's total surface area (71.5 × 71.5 cm), and the surfaces were sampled with an individual robot in an isolation chamber. Chamber air was sampled using a biofilter sampler to determine the potential for resuspension of spores during sampling. Robot test results were compared to currently used surface sampling methods (vacuum sock for carpet and sponge wipe for laminate). The test results showed that the average sampling efficacies for R1, R2, and R3 on carpet were 26, 162, and 92% of vacuum sock sampling efficacy, respectively. On laminate, R1, R2, R3, R4, and R5 average sampling efficacies were 8, 11, 2, 62, and 32% of sponge wipe sampling efficacy, respectively. We conclude that some robotic cleaners were as efficacious as the currently used surface sampling methods for B. atrophaeus spores on these surfaces.

  15. Surface and bulk effects in silica fibers caused by 405 nm CW diode laser irradiation and means for mitigation

    NASA Astrophysics Data System (ADS)

    Gonschior, C. P.; Klein, K.-F.; Sun, T.; Grattan, K. T. V.

    2012-11-01

    Surface and bulk effects in silica optics due to high intensity laser light are well known using short pulse and high power laser systems. Surfaces are quickly destroyed mechanically if not properly prepared and thoroughly cleaned. Linear and non-linear absorption of high intensity laser light in the bulk of the optics causes material modifications, like voids, cracks and UV defects. In ablation experiments with very short pulses on wide band-gap dielectrics, periodic surface structures in the form of ripples were found. Surprisingly, we found similar structures on fiber end-faces after long-term irradiation with 405 nm CW laser light. Power densities on the end-face are in the range of 1 MW/cm2, three magnitudes of order below the power threshold at which the described damages occur. Nevertheless a ripple structure perpendicular to the polarization direction of the laser was formed and grows with irradiation time. An increased absorption band at 214 nm (E' center) along the fiber was discovered by spectral absorption measurements. E' centers can be generated by 405 nm laser light in the bulk, therefore defects on the surface are possible as well. The generation of defect centers on the silica surface can enhance the formation of an unstable surface layer.

  16. Self-cleaning superhydrophobic surface based on titanium dioxide nanowires combined with polydimethylsiloxane

    NASA Astrophysics Data System (ADS)

    Zhang, Xia; Guo, Yonggang; Zhang, Zhijun; Zhang, Pingyu

    2013-11-01

    The present work describes a simple dipping process for the preparation of superhydrophobic coatings based on titanium dioxide nanowires combined with polydimethylsiloxane. The coating surface morphology, composition and wettability were investigated by scanning electron microscope, X-ray photoelectron spectroscope and contact angle measurements, respectively. Interestingly, the superhydrophobic coatings turn into a hydrophilic one after UV irradiation. It is found that the superhydrophobic surface shows almost complete wet self-cleaning of dirt particles with water droplets. Furthermore, the coating surface shows the anti-fouling performance for organic solvents, which can self-remove the organic solvents layer and recovers its superhydrophobic behavior. The advantage of the present approach is that the damaged coating can be easily repaired.

  17. Preparation of self-cleaning surfaces with a dual functionality of superhydrophobicity and photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Park, Eun Ji; Yoon, Hye Soo; Kim, Dae Han; Kim, Yong Ho; Kim, Young Dok

    2014-11-01

    Thin film of polydimethylsiloxane (PDMS) was deposited on SiO2 nanoparticles by chemical vapor deposition, and SiO2 became completely hydrophobic after PDMS coating. Mixtures of TiO2 and PDMS-coated SiO2 nanoparticles with various relative ratios were prepared, and distributed on glass surfaces, and water contact angles and photocatalytic activities of these surfaces were studied. Samples consisting of TiO2 and PDMS-coated SiO2 with a ratio of 7:3 showed a highly stable superhydrophobicity under UV irradiation with a water contact angle of 165° and UV-driven photocatalytic activity for decomposition of methylene blue and phenol in aqueous solution. Our process can be exploited for fabricating self-cleaning surfaces with dual functionality of superhydrophobicity and photocatalytic activity at the same time.

  18. Mechanically durable superoleophobic aluminum surfaces with microstep and nanoreticula hierarchical structure for self-cleaning and anti-smudge properties.

    PubMed

    Peng, Shan; Bhushan, Bharat

    2016-01-01

    Superoleophobic aluminum surfaces are of interest for self-cleaning, anti-smudge (fingerprint resistance), anti-fouling, and corrosion resistance applications. In the published literature on superoleophobic aluminum surfaces, mechanical durability, self-cleaning, and anti-smudge properties data are lacking. Microstep structure has often been used to prepare superhydrophobic aluminum surfaces which produce the microstructure. The nanoreticula structure has also been used, and is reported to be able to trap air-pockets, which are desirable for a high contact angle. In this work, the microstep and nanoreticula structures were produced on aluminum surfaces to form a hierarchical micro/nanostructure by a simple two-step chemical etching process. The hierarchical structure, when modified with fluorosilane, made the surface superoleophobic. The effect of nanostructure, microstructure, and hierarchical structure on wettability and durability were studied and compared. The superoleophobic aluminum surfaces were found to be wear resistant, self-cleaning, and have anti-smudge and corrosion resistance properties.

  19. Biotin chemisorption on clean and hydroxylated Si-SiC(001) surfaces

    NASA Astrophysics Data System (ADS)

    Kanai, Yosuke; Cicero, Giancarlo; Selloni, Annabella

    2005-03-01

    In recent years, there have been substantial experimental efforts toward achieving nanoscale functionalization of semiconductor surfaces. One of the main motivations of such experiments is biosensing application. Biotin is a leading candidate for such functionalization because of its strong, unmatched affinity to specific proteins such as Streptavidin. On the other hand, silicon carbide (SiC) has emerged as a promising biocompatible material that may be employed in new biomedical devices. Using Density Functional Theory, we have carried out a theoretical investigation of the structural and electronic properties of biotin after chemisorption on both the clean and hydroxylated Si-SiC(001). We find that, upon chemisorption, Biotin retains the electronic properties responsible for its strong affinity to proteins. While the electronic states of the hydroxylated surface undergo negligible changes in the presence of biotin, those of the clean surface are substantially affected by the presence of the molecule. This work was performed under the auspices of the U.S. Department of Energy by University of California Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.

  20. Femtosecond laser surface patterning of steel and titanium alloy

    NASA Astrophysics Data System (ADS)

    Milovanović, D. S.; Gaković, B.; Radu, C.; Zamfirescu, M.; Radak, B.; Petrović, S.; Rogić Miladinović, Z.; Mihailescu, I. N.

    2014-09-01

    In this work, we present the results obtained by femtosecond laser processing of AISI D2 steel and the widely applicable titanium-based alloy, Ti6Al4V. Patterning the materials’ surfaces was done by a Ti:sapphire system at 775 nm wavelength and 200 fs pulse duration, while varying the output pulse energies and the scanning speed. The formation of laser-induced periodical surface structures were found for both materials.

  1. SEMICONDUCTOR TECHNOLOGY: GaAs surface wet cleaning by a novel treatment in revolving ultrasonic atomization solution

    NASA Astrophysics Data System (ADS)

    Zaijin, Li; Liming, Hu; Ye, Wang; Ye, Yang; Hangyu, Peng; Jinlong, Zhang; Li, Qin; Yun, Liu; Lijun, Wang

    2010-03-01

    A novel process for the wet cleaning of GaAs surface is presented. It is designed for technological simplicity and minimum damage generated within the GaAs surface. It combines GaAs cleaning with three conditions consisting of (1) removal of thermodynamically unstable species and (2) surface oxide layers must be completely removed after thermal cleaning, and (3) a smooth surface must be provided. Revolving ultrasonic atomization technology is adopted in the cleaning process. At first impurity removal is achieved by organic solvents; second NH4OH:H2O2:H2O = 1:1:10 solution and HCl: H2O2:H2O = 1:1:20 solution in succession to etch a very thin GaAs layer, the goal of the step is removing metallic contaminants and forming a very thin oxidation layer on the GaAs wafer surface; NH4OH:H2O = 1:5 solution is used as the removed oxide layers in the end. The effectiveness of the process is demonstrated by the operation of the GaAs wafer. Characterization of the oxide composition was carried out by X-ray photoelectron spectroscopy. Metal-contamination and surface morphology was observed by a total reflection X-ray fluorescence spectroscopy and atomic force microscope. The research results show that the cleaned surface is without contamination or metal contamination. Also, the GaAs substrates surface is very smooth for epitaxial growth using the rotary ultrasonic atomization technology.

  2. Femtosecond laser surface structuring technique for making human enamel and dentin surfaces superwetting

    NASA Astrophysics Data System (ADS)

    Vorobyev, A. Y.; Guo, Chunlei

    2013-12-01

    It is known that good wettability of enamel and dentin surfaces is a key factor in enhancing adhesion of restorative materials in dentistry. Here, we report on a femtosecond laser surface texturing approach that makes both the enamel and dentine surfaces superwetting. In contrast to the traditional chemical etching that yields random surface structures, this new approach produces engineered surface structures. The surface structure engineered and tested here is an array of femtosecond laser-produced parallel microgrooves that generates a strong capillary force. Due to the powerful capillary action, water is rapidly sucked into this engineered surface structure and spreads even on a vertical surface.

  3. Robust non-wetting PTFE surfaces by femtosecond laser machining.

    PubMed

    Liang, Fang; Lehr, Jorge; Danielczak, Lisa; Leask, Richard; Kietzig, Anne-Marie

    2014-08-08

    Nature shows many examples of surfaces with extraordinary wettability,which can often be associated with particular air-trapping surface patterns. Here,robust non-wetting surfaces have been created by femtosecond laser ablation of polytetrafluoroethylene (PTFE). The laser-created surface structure resembles a forest of entangled fibers, which support structural superhydrophobicity even when the surface chemistry is changed by gold coating. SEM analysis showed that the degree of entanglement of hairs and the depth of the forest pattern correlates positively with accumulated laser fluence and can thus be influenced by altering various laser process parameters. The resulting fibrous surfaces exhibit a tremendous decrease in wettability compared to smooth PTFE surfaces; droplets impacting the virgin or gold coated PTFE forest do not wet the surface but bounce off. Exploratory bioadhesion experiments showed that the surfaces are truly air-trapping and do not support cell adhesion. Therewith, the created surfaces successfully mimic biological surfaces such as insect wings with robust anti-wetting behavior and potential for antiadhesive applications. In addition, the fabrication can be carried out in one process step, and our results clearly show the insensitivity of the resulting non-wetting behavior to variations in the process parameters,both of which make it a strong candidate for industrial applications.

  4. Laser-induced nanoscale superhydrophobic structures on metal surfaces.

    PubMed

    Jagdheesh, R; Pathiraj, B; Karatay, E; Römer, G R B E; Huis in't Veld, A J

    2011-07-01

    The combination of a dual-scale (nano and micro) roughness with an inherent low-surface energy coating material is an essential factor for the development of superhydrophobic surfaces. Ultrashort pulse laser (USPL) machining/structuring is a promising technique for obtaining the dual-scale roughness. Sheets of stainless steel (AISI 304 L SS) and Ti-6Al-4V alloys were laser-machined with ultraviolet laser pulses of 6.7 ps, with different numbers of pulses per irradiated area. The surface energy of the laser-machined samples was reduced via application of a layer of perfluorinated octyltrichlorosilane (FOTS). The influence of the number of pulses per irradiated area on the geometry of the nanostructure and the wetting properties of the laser-machined structures has been studied. The results show that with an increasing number of pulses per irradiated area, the nanoscale structures tend to become predominantly microscale. The top surface of the microscale structures is seen covered with nanoscale protrusions that are most pronounced in Ti-6Al-4V. The laser-machined Ti-6Al-4V surface attained superhydrophobicity, and the improvement in the contact angle was >27% when compared to that of a nontextured surface.

  5. High resolution electron energy loss spectroscopy of clean and hydrogen covered Si(001) surfaces: first principles calculations.

    PubMed

    Patterson, C H

    2012-09-01

    Surface phonons, conductivities, and loss functions are calculated for reconstructed (2×1), p(2×2) and c(4×2) clean Si(001) surfaces, and (2×1) H and D covered Si(001) surfaces. Surface conductivities perpendicular to the surface are significantly smaller than conductivities parallel to the surface. The surface loss function is compared to high resolution electron energy loss measurements. There is good agreement between calculated loss functions and experiment for H and D covered surfaces. However, agreement between experimental data from different groups and between theory and experiment is poor for clean Si(001) surfaces. Formalisms for calculating electron energy loss spectra are reviewed and the mechanism of electron energy losses to surface vibrations is discussed.

  6. Laser-Driven Corrugation Instability of Liquid Metal Surfaces

    NASA Astrophysics Data System (ADS)

    Keilmann, Fritz

    1983-12-01

    During intense CO2-laser irradiation deep corrugations build up on liquid metals such as Hg, In, Sn, Al, and Pb. Spacing, orientation, growth, and decay of the corrugations are studied, by visible light diffraction; support is found for a model of stimulated scattering where the incident light parametrically decays into both the surface corrugation and a surface plasmon. Thermal evaporation supplies the nonlinearity. The instability provides polarization-dependent absorption and can be expected in laser-metalworking and laser-plasma situations.

  7. Femtosecond laser-induced periodic surface structure formation on tungsten

    SciTech Connect

    Vorobyev, A. Y.; Guo Chunlei

    2008-09-15

    In this paper, we demonstrate the generation of periodic surface structures on a technologically important material, tungsten, at both 400 and 800 nm, despite that the table values of dielectric constants for tungsten at these two wavelengths suggest the absence of surface plasmons, a wave necessary for forming periodic structures on metals. Furthermore, we find that the structure periods formed on tungsten are significantly less than the laser wavelengths. We believe that the dielectric constants of tungsten change significantly due to intense laser pulse heating and surface structuring and roughening at nanometer scales, permitting surface plasmon excitation and periodic structure formation.

  8. Impurities removal by laser blow-off from in-vacuum optical surfaces on RFX-mod experiment

    SciTech Connect

    Alfier, A.; Fassina, A.; Pasqualotto, R.; Cervaro, V.; Lotto, L.; Barison, S.; Fiameni, S.; Giudicotti, L.

    2010-12-15

    An in situ window cleaning system by laser blow-off through optical fiber has been developed on the basis of a feasibility study previously presented. The beam generated by a Q-switched Nd:YAG laser is launched in a vacuum box into a high damage threshold optical fiber through a lens. The fiber output is focused on the impurities-coated surface of a vacuum window exposed to the plasma of the RFX-mod experiment, and it is remotely controlled with an xy motion system to scan the entire surface. We first investigate the energy density threshold necessary to ablate the deposited impurity substrate on removed dirty windows: above threshold, a single laser pulse recovers {approx}95% of the window transmission before its exposure to the plasma, while below it the efficiency of the cleaning process is too poor. The system so conceived was then used to clean the three collection windows of the Main Thomson scattering diagnostic on RFX-mod. We also present results obtained applying the same technique to the SiO-protected Al mirror used for the Z{sub eff} diagnostic: an energy threshold for efficient impurity removal without mirror damage is first identified, then ablation tests are executed and analyzed in terms of recovered reflectivity. The SIMS technique is used both with windows and mirror to study the composition of surfaces before and after the ablation.

  9. Impurities removal by laser blow-off from in-vacuum optical surfaces on RFX-mod experiment

    NASA Astrophysics Data System (ADS)

    Alfier, A.; Barison, S.; Fassina, A.; Fiameni, S.; Giudicotti, L.; Pasqualotto, R.; Cervaro, V.; Lotto, L.

    2010-12-01

    An in situ window cleaning system by laser blow-off through optical fiber has been developed on the basis of a feasibility study previously presented. The beam generated by a Q-switched Nd:YAG laser is launched in a vacuum box into a high damage threshold optical fiber through a lens. The fiber output is focused on the impurities-coated surface of a vacuum window exposed to the plasma of the RFX-mod experiment, and it is remotely controlled with an xy motion system to scan the entire surface. We first investigate the energy density threshold necessary to ablate the deposited impurity substrate on removed dirty windows: above threshold, a single laser pulse recovers ˜95% of the window transmission before its exposure to the plasma, while below it the efficiency of the cleaning process is too poor. The system so conceived was then used to clean the three collection windows of the Main Thomson scattering diagnostic on RFX-mod. We also present results obtained applying the same technique to the SiO-protected Al mirror used for the Zeff diagnostic: an energy threshold for efficient impurity removal without mirror damage is first identified, then ablation tests are executed and analyzed in terms of recovered reflectivity. The SIMS technique is used both with windows and mirror to study the composition of surfaces before and after the ablation

  10. Modifying molecule-surface scattering by ultrashort laser pulses

    SciTech Connect

    Khodorkovsky, Yuri; Averbukh, Ilya Sh.; Manson, J. R.

    2011-11-15

    In recent years it has become possible to align molecules in free space using ultrashort laser pulses. Here we explore two schemes for controlling molecule-surface scattering processes and which are based on laser-induced molecular alignment. In the first scheme, a single ultrashort nonresonant laser pulse is applied to a molecular beam hitting the surface. This pulse modifies the angular distribution of the incident molecules and causes the scattered molecules to rotate with a preferred sense of rotation (clockwise or counterclockwise). In the second scheme, two properly delayed laser pulses are applied to a molecular beam composed of two chemically close molecular species (isotopes, or nuclear-spin isomers). As the result of the double-pulse excitation, these species are selectively scattered to different angles after the collision with the surface. These effects may provide new means for the analysis and separation of molecular mixtures.

  11. Laser-based nanoengineering of surface topographies for biomedical applications

    NASA Astrophysics Data System (ADS)

    Schlie, Sabrina; Fadeeva, Elena; Koroleva, Anastasia; Ovsianikov, Aleksandr; Koch, Jürgen; Ngezahayo, Anaclet; Chichkov, Boris. N.

    2011-04-01

    In this study femtosecond laser systems were used for nanoengineering of special surface topographies in silicon and titanium. Besides the control of feature sizes, we demonstrated that laser structuring caused changes in material wettability due to a reduced surface contact area. These laser-engineered topographies were tested for their capability to control cellular behavior of human fibroblasts, SH-SY5Y neuroblastoma cells, and MG-63 osteoblasts. We found that fibroblasts reduced cell growth on the structures, while the other cell types proliferated at the same rate. These findings make laser-surface structuring very attractive for biomedical applications. Finally, to explain the results the correlation between topography and the biophysics of cellular adhesion, which is the key step of selective cell control, is discussed.

  12. SURFACE MORPHOLOGY OF CARBON FIBER POLYMER COMPOSITES AFTER LASER STRUCTURING

    SciTech Connect

    Sabau, Adrian S; Chen, Jian; Jones, Jonaaron F.; Alexandra, Hackett; Jellison Jr, Gerald Earle; Daniel, Claus; Warren, Charles David; Rehkopf, Jackie D.

    2015-01-01

    The increasing use of Carbon Fiber Polymer Composite (CFPC) as a lightweight material in automotive and aerospace industries requires the control of surface morphology. In this study, the composites surface was prepared by ablating the resin in the top fiber layer of the composite using an Nd:YAG laser. The CFPC specimens with T700S carbon fiber and Prepreg - T83 resin (epoxy) were supplied by Plasan Carbon Composites, Inc. as 4 ply thick, 0/90o plaques. The effect of laser fluence, scanning speed, and wavelength was investigated to remove resin without an excessive damage of the fibers. In addition, resin ablation due to the power variation created by a laser interference technique is presented. Optical property measurements, optical micrographs, 3D imaging, and high-resolution optical profiler images were used to study the effect of the laser processing on the surface morphology.

  13. Surface roughness measurement of tooling spheres for laser measurements

    NASA Astrophysics Data System (ADS)

    Sarr, Dennis P.; Reed, Paul W.

    2001-02-01

    The usage of chrome or highly polished precision tooling (reference) spheres is common in the calibration and operational characterization of measurement systems such as a Coordinate Measurement Machine (CMM). The usage of a three-dimensional, (3D) laser triangulation, non-contact measurement system on CMMs and other scanning systems pose several obstacles. The highly specular mirror finish on the tooling sphere provides an accurate mechanical entity that has adverse results with laser sensors. The development of tooling spheres with a diffuse surface would benefit laser based measurement systems. The surface roughness and reflectivity properties have an effect on the laser measurements' accuracy. Efforts to develop spheres and establish meaningful measurements of spheres with modified surface finishes are investigated.

  14. Method for Selective Cleaning of Mold Release from Composite Honeycomb Surfaces

    NASA Technical Reports Server (NTRS)

    Pugel, Diane

    2011-01-01

    Honeycomb structures are commonly employed as load- and force-bearing structures as they are structurally strong and lightweight. Manufacturing processes for heat-molded composite honeycomb structures commence with the placement of pre-impregnated composite layups over metal mandrels. To prevent permanent bonding between the composite layup and the metal mandrels, an agent, known as a mold release agent, is used. Mold release agents allow the molded composite material to be removed from mandrels after a heat-forming process. Without a specific removal process, mold release agents may continue to adhere to the surface of the composite material, thereby affecting the bonding of other materials that may come into contact with the composite surface in later stages of processing A constituent common to commercially available household cleaning agents is employed for the removal of mold release agents common to the manufacturing of heat-formed composite materials. The reliability of the solvent has been proven by the longevity and reliability of commercial household cleaners. At the time of this reporting, no one has attempted using constituent for this purpose. The material to be cleaned is immersed in the solution, vertically removed so that the solution is allowed to drain along cell walls and into a solvent bath, and then placed on a compressed airflow table for drying.

  15. Picosecond laser surface micropatterning of ceramics by optical fiber induction

    NASA Astrophysics Data System (ADS)

    Li, Jian; Ji, Lingfei; Hu, Yan; Wu, Yan; Yan, Yinzhou

    2015-06-01

    Parallel microgrooves and mesh structure with a line width of about 16 μm, which is much smaller than the diameter of the laser focus spot of 50 μm, are fabricated on Al2O3 ceramic surfaces by picosecond laser patterning with optical fiber induction. The patterned grooves are of high quality without burr, recasting or thermally induced cracks. Grain refinement of the groove surfaces caused by the rapid condensation and redeposition during picosecond laser irradiation with optical fiber induction improved the smoothness and mechanical strength of the grooves. Different patterns can be fabricated by adjusting the optical fiber layout, which is independent of the laser scanning direction. The regions etched by the laser are kept in near-field contact with the optical fibers when the laser beam passes through the fibers and irradiates the ceramic surface. This results in localized field enhancement between the transparent optic fiber and ceramic surface, which produces the precise microgrooves. The developed technique allows high-resolution micromachining of the surfaces of hard and brittle ceramic-type materials.

  16. Comparative first-principles study of clean-surface properties of metals

    NASA Astrophysics Data System (ADS)

    Patra, Abhirup; Sun, Jianwei; Perdew, John P.

    Metal surfaces are widely used in different applications from nano-devices to heterogeneous catalysis. Clean-surface properties such as the surface energy, work function and interlayer spacing importantly determine the behavior of metal surfaces. Prior work has been done to understand these properties using high-level methods including the local density approximation (LDA) and the generalized gradient approximation (PBE). In this work, we study (111) (100) and (110) surfaces of Pt, Pd, Cu, Al, Au, Ag, Rh and Ru by extrapolation from a finite number of layers. These surfaces are studied using SCAN, a new member of the computationally-efficient meta-GGA family of density functionals. We have compared the performance of SCAN and three other standard density functionals - LDA, PBE and PBEsol - to available experimental results. We find that the performance of the general-purpose SCAN is at the level of the more-specialized PBEsol, giving accurate metallic properties. Ref: Jianwei Sun, Adrienn Ruzsinszky, John P Perdew, Strongly Constrained and Appropriately Normed Semilocal Density Functional, Physical Review Letters115 (3), 036402 (2015). Supported by NSF under DMR-1305135, CNS-09-5884, and by DOE under DE-SC0012575, DE-AC02-05CH11231.

  17. Influence of Surface Pre-treatments on Laser Welding of Ti6Al4V Alloy

    NASA Astrophysics Data System (ADS)

    Sánchez-Amaya, J. M.; Amaya-Vázquez, M. R.; González-Rovira, L.; Botana-Galvin, M.; Botana, F. J.

    2014-05-01

    In the present study, Ti6Al4V samples have been welded under conduction regime by means of a high power diode laser. The main objective of the work has been to determine the actual influence of the surface pre-treatments on the laser welding process. Thus, six different pre-treatments were applied to Ti6Al4V samples before performing bead-on-plate and butt welding treatments. The depth, width, microstructure, and microhardness of the different weld zones were deeply analyzed. Grinding, sandblasting, and chemical cleaning pre-treatments lead to welds with the highest depth values, presenting high joint strengths. Treatments based on the application of dark coatings generate welds with lower penetration and worse mechanical properties, specially the graphite-based coating.

  18. Nanoparticles based laser-induced surface structures formation on mesoporous silicon by picosecond laser beam interaction

    NASA Astrophysics Data System (ADS)

    Talbi, A.; Petit, A.; Melhem, A.; Stolz, A.; Boulmer-Leborgne, C.; Gautier, G.; Defforge, T.; Semmar, N.

    2016-06-01

    In this study, laser induced periodic surface structures were formed on mesoporous silicon by irradiation of Nd:YAG picosecond pulsed laser beam at 266 nm wavelength at 1 Hz repetition rate and with 42 ps pulse duration. The effects of laser processing parameters as laser beam fluence and laser pulse number on the formation of ripples were investigated. Scanning electron microscopy and atomic force microscopy were used to image the surface morphologies and the cross section of samples after laser irradiation. At relatively low fluence ∼20 mJ/cm2, ripples with period close to the laser beam wavelength (266 nm) and with an always controlled orientation (perpendicular to the polarization of ps laser beam) appeared after a large laser pulse number of 12,000. It has been found that an initial random distribution of SiOx nanoparticles is periodically structured with an increase of the laser pulse number. Finally, it is experimentally demonstrated that we formed a 100 nm liquid phase under the protusion zones including the pores in the picosecond regime.

  19. Long wavelength vertical cavity surface emitting laser

    DOEpatents

    Choquette, Kent D.; Klem, John F.

    2005-08-16

    Selectively oxidized vertical cavity lasers emitting near 1300 nm using InGaAsN quantum wells are reported for the first time which operate continuous wave below, at and above room temperature. The lasers employ two n-type Al.sub.0.94 Ga.sub.0.06 As/GaAs distributed Bragg reflectors each with a selectively oxidized current aperture adjacent to the active region, and the top output mirror contains a tunnel junction to inject holes into the active region. Continuous wave single mode lasing is observed up to 55.degree. C.

  20. Oriented cluster formation of endohedral Y@C{sub 82} metallofullerenes on clean surfaces

    SciTech Connect

    Shinohara, Hisanori; Inakuma, Masayasu; Kishida, Masaaki; Yamazaki, Souichi; Hashizume, Tomihiro; Sakurai, Toshio

    1995-09-21

    An oriented head-to-tail cluster formation of an endohedral yttrium metallofullerene, Y@C{sub 82}, on a Cu(111)I x 1 clean surface has been observed directly by the use of a scanning tunneling microscopy (STM) under ultrahigh-vacuum conditions. The STM observation reveals that the Y@C{sub 82} molecules preferentially form dimers and one-dimensional clusters at the step edge of the Cu(111) surface. The observed intermolecular distance (11.2 {+-} 0.5 A) is smaller than that of the simple Y@C{sub 82}, Y@C{sub 82} van der Waals distance (11.4 A), indicating the presence of a strong interfullerene interaction. The STM results suggest the presence of strong dipole-dipole and charge-transfer interactions among Y@C{sub 82} fullerenes. Such a molecule has a great similarity to the `superatom` features proposed theoretically in a semiconductor heterostructure. 30 refs., 5 figs.

  1. Cleaning of the Moscow SIA ``Radon`` surface water runoff: Problems and solutions

    SciTech Connect

    Barinov, A.S.; Volkov, A.S.; Karlin, Y.V.; Kropotov, V.N.

    1996-08-01

    This paper describes a three-barrier system of engineered safety features for the cleaning of the Moscow SIA ``Radon`` surface water runoff. The three-barrier system is under development, but several components have been put into operation. For example, in 1995 more than 400 cubic meters of radioactive water (containing 1,500 Bk/l initial specific activity of beta-emitting nuclides and 30 Bk/l initial specific activity of alpha-emitting nuclides) was purified using the ``Aqua-express`` filtration and ultrafiltration modules. Since 1990, solid particles have been removed from the surface water runoff by the two pond settlers. It is hoped that the entire system will be put into operation not later than the year 2000.

  2. Laboratory evaluation of disposable and reusable disinfectant cloths for cleaning food contact surfaces.

    PubMed

    Tebbutt, G M

    1988-10-01

    A comparison of five methods of cleaning Formica surfaces contaminated with bacteria dried in milk has been carried out. A standardized procedure was developed, and impression plates were found to be at least as sensitive as a swab-rinse method for detecting bacteria on the surfaces. The most satisfactory results were obtained with one type of disposable alcohol-impregnated wipe and with a detergent/hypochlorite solution applied with paper. A reusable cloth impregnated with disinfectant initially performed well against all test organisms, but was less reliable against Staphylococcus aureus and Streptococcus faecalis, after the cloth had been used and rinsed several times. The importance of introducing methods to reduce the high risk of cross-contamination presently associated with the use of wiping cloths in catering premises is stressed.

  3. Cleaning Surface Particle Contamination with Ultrapure Water (UPW) Megasonic Flow on Genesis Array Collectors

    NASA Technical Reports Server (NTRS)

    Allton, J. H.; Calaway, Michael J.; Hittle, J. D.; Rodriquez, M. C.; Stansbery, E. K.; McNamara, K. M.

    2006-01-01

    The hard landing experienced by the Genesis sample return capsule breached the science canister containing the solar wind collectors. This impact into the damp lakebed contaminated collector surfaces with pulverized collector and spacecraft materials and Utah sediment and brine residue. The gold foil, polished aluminum, and bulk metallic glass remained intact, but the solar wind bulk and regime-specific array collectors were jarred loose from their frames and fractured into greater than 10,000 specimens. After a year of investigation and cleaning experimentation, the Genesis Science Team determined that array collectors had 4 classes of contaminants: particles, molecular film, submicron inorganic particulate ("aerosol"), and pre-launch surface contamination. We discuss here use of megasonically energized ultrapure water (UPW) for removing particulate debris from array collector fragments.

  4. Hydrogen radical processing -- In-situ semiconductor surface cleaning for epitaxial regrowth

    SciTech Connect

    Kuenzel, H.; Hase, A.; Griebenow, U.

    1996-12-31

    The achievement of high-quality interfaces for improved semiconductor device structures necessitates in-situ surface cleaning between different material deposition processes. In this contribution in-situ hydrogen radical exposure is presented as an advanced technique to obtain semiconductor surfaces adequate for MBE regrowth. Exposure of In-P-based materials to a thermal hydrogen radical beam at relatively low temperatures removes the native oxide layer from GaInAsP as well as AlGaInAs. In addition, accumulation of carbon, being the most prominent contaminant due to the exposure to air or intermediate ex-situ processing steps, is efficiently reduced. There is no indication of the occurrence of degradation of the treated material due to the hydrogen radical process which makes it especially suited for the fabrication of complex device structures.

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

    SciTech Connect

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

    2015-03-15

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

  6. [Influence of an Er:YAG laser on the surface structure of titanium implants].

    PubMed

    Schwarz, Frank; Rothamel, Daniel; Becker, Jürgen

    2003-01-01

    In addition to conventional treatment modalities (mechanical and chemical), the use of lasers has been proposed for cleaning and detoxification of implant surfaces. The aim of the present clinical investigation was (1) to evaluate the effects of an Er:YAG laser on the surface properties of titanium implants in vivo and (2) to determine the effectiveness of this treatment modality for subgingival calculus removal. This investigation was conducted on eight implants of two patients, considered for explantation due to severe peri-implantitis inflammation. Immediately before explanatation, six implants were instrumented subgingivally with an Er:YAG laser (100 mJ/pulse and 10 Hz). Two implants served as a control. All titanium implants were examined using scanning electron microscopy by one calibrated and blinded examiner. In comparison to the untreated control group, non-surgical instrumentation of titanium implants with an Er:YAG laser resulted in an effective removal of subgingival calculus without leading to any thermal damages. However, all samples of the test group revealed amounts of residual debris which should be taken into account under clinical conditions.

  7. SEMICONDUCTOR TECHNOLOGY A new cleaning process for the metallic contaminants on a post-CMP wafer's surface

    NASA Astrophysics Data System (ADS)

    Baohong, Gao; Yuling, Liu; Chenwei, Wang; Yadong, Zhu; Shengli, Wang; Qiang, Zhou; Baimei, Tan

    2010-10-01

    This paper presents a new cleaning process using boron-doped diamond (BDD) film anode electrochemical oxidation for metallic contaminants on polished silicon wafer surfaces. The BDD film anode electrochemical oxidation can efficiently prepare pyrophosphate peroxide, pyrophosphate peroxide can oxidize organic contaminants, and pyrophosphate peroxide is deoxidized into pyrophosphate. Pyrophosphate, a good complexing agent, can form a metal complex, which is a structure consisting of a copper ion, bonded to a surrounding array of two pyrophosphate anions. Three polished wafers were immersed in the 0.01 mol/L CuSO4 solution for 2 h in order to make comparative experiments. The first one was cleaned by pyrophosphate peroxide, the second by RCA (Radio Corporation of America) cleaning, and the third by deionized (DI) water. The XPS measurement result shows that the metallic contaminants on wafers cleaned by the RCA method and by pyrophosphate peroxide is less than the XPS detection limits of 1 ppm. And the wafer's surface cleaned by pyrophosphate peroxide is more efficient in removing organic carbon residues than RCA cleaning. Therefore, BDD film anode electrochemical oxidation can be used for microelectronics cleaning, and it can effectively remove organic contaminants and metallic contaminants in one step. It also achieves energy saving and environmental protection.

  8. Mesoscopic organization of cobalt thin films on clean and oxygen-saturated Fe(001) surfaces

    NASA Astrophysics Data System (ADS)

    Riva, M.; Picone, A.; Giannotti, D.; Brambilla, A.; Fratesi, G.; Bussetti, G.; Duò, L.; Ciccacci, F.; Finazzi, M.

    2015-09-01

    The different morphologies of Co films grown on either the clean Fe(001) surface and the oxygen-saturated Fe(001)-p (1 ×1 ) O substrate are investigated by means of scanning tunneling microscopy, Auger electron spectroscopy, and density functional theory. The considered Co coverage range extends beyond the thickness at which layer-by-layer growth is destabilized by plastic deformations induced by the relaxation of the strain accumulated in the film. Our findings indicate that the oxygen overlayer of the Fe(001)-p (1 ×1 ) O surface floats on top of the growing Co film and strongly influences both the Co nucleation process and the film structural evolution. The layer-dependent islands nucleation of Co films grown on clean Fe(001) substrates, recently associated with a thickness-dependent adatom mobility [A. Picone et al., Phys. Rev. Lett. 113, 046102 (2014), 10.1103/PhysRevLett.113.046102], is found to be suppressed by the oxygen overlayer. The latter also significantly delays the layer-by-layer instability with respect to the oxygen-free growth. Furthermore, the body-centered-tetragonal/hexagonal-close-packed transition is not observed in the case of Co/Fe(001)-p (1 ×1 ) O sample, replaced by the development of highly ordered surface undulations. These form a mesoscopic square pattern with the sides aligned to the Fe <110 > directions, while the surface atomic structure retains the square p (1 ×1 ) symmetry in registry with the substrate. Such undulations are likely generated by a highly ordered array of interfacial misfit dislocations running along the Fe <110 > directions.

  9. Laser and chemical surface modifications of titanium grade 2 for medical application

    NASA Astrophysics Data System (ADS)

    Kwaśniak, P.; Pura, J.; Zwolińska, M.; Wieciński, P.; Skarżyński, H.; Olszewski, L.; Marczak, J.; Garbacz, H.; Kurzydłowski, K. J.

    2015-05-01

    The article presents combined, chemical and physical approach to titanium surface functionalization designed for biomedical applications. The topography modification has been obtained by employing the double laser beam interference technique and chemical etching. In the outcome, clean and smooth Ti surface as well as periodic striated topography with the roughness range from nano- to micrometers were created. The obtained structures were characterized in terms of shape, roughness, chemical composition, mechanical properties and microstructures. In order to achieve all information, numerous of research methods have been used: scanning electron microscopy, atomic force microscopy, optical profilometry and microhardness measurements. Demonstrated methodology can be used as an effective tool for manufacturing controlled surface structures improving the bone-implants interactions.

  10. Laser annealing of silicon surface defects for photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Sun, Zeming; Gupta, Mool C.

    2016-10-01

    High power lasers are increasingly used for low cost fabrication of solar cell devices. High power laser processes generate crystal defects, which lower the cell efficiency. This study examines the effect of low power laser annealing for the removal of high power laser induced surface defects. The laser annealing behavior is demonstrated by the significant decrease of photoluminescence generated from dislocation-induced defects and the increase of band-to-band emission. This annealing effect is further confirmed by the X-ray diffraction peak reversal. The dislocation density is quantified by observing etch pits under the scanning electron microscope (SEM). For as-melted samples, the dislocation density is decreased to as low as 1.01 × 106 cm- 2 after laser annealing, resulting in an excellent surface carrier lifetime of 920 μs that is comparable to the value of 1240 μs for the silicon starting wafer. For severely defective samples, the dislocation density is decreased by 4 times and the surface carrier lifetime is increased by 5 times after laser annealing.

  11. Pulse laser particulate separation from polycarbonate: surface acoustic wave and thermomechanical mechanisms

    NASA Astrophysics Data System (ADS)

    Arif, S.; Armbruster, O.; Kautek, W.

    2013-05-01

    The mechanisms of graphite particle and polystyrene-co-divinyl benzene microsphere removal from flat polycarbonate substrates by nanosecond pulse laser interaction at 532 nm were studied both experimentally and theoretically. These model contaminants exhibited an extremely contrasting behavior in respect to phase separation and collateral damage to the polycarbonate substrate. Opaque graphite particles within the irradiated spot area either desorbed due to their thermal expansion or undertook vaporization/ablation. The transparent polystyrene microspheres caused local ablation of the substrate in their optical near-field. This process led to the removal of the particles, but eradicated the available cleaning fluence window. The opaque graphite particles, on the other hand, showed efficient clearance, particularly in a practicable cleaning window above 0.5~J/cm2 and low pulse numbers of about two. Besides the mechanisms occurring within the irradiated spot, a separation process in the proximity beyond the laser spot (more than double the Gaussian radius) could be related to the action of high-amplitude surface acoustic waves (SAW). A minimum surface acceleration of 109~cm/s2 was calculated to be sufficient to overcome the adhesion forces in this particle separation model.

  12. Surface force measurements between titanium dioxide surfaces prepared by atomic layer deposition in electrolyte solutions reveal non-DLVO interactions: influence of water and argon plasma cleaning.

    PubMed

    Walsh, Rick B; Evans, Drew; Craig, Vincent S J

    2014-03-01

    Surface force measurements between titania surfaces in electrolyte solutions have previously revealed an unexplained long-range repulsive force at high pH, not described by Derjaguin, Landau, Verwey, and Overbeek (DLVO) theory. Here, the surface forces between titania surfaces produced by atomic layer deposition (ALD) and cleaned using a variety of methods have been measured to determine the influence of the cleaning protocol on the measured forces and test the hypothesis that water plasma cleaning of the surface results in non-DLVO forces at high pH. For argon plasma and water plasma cleaned surfaces, a diffuse double layer repulsion and van der Waals attraction is observed near the isoelectric point. At high pH, the force remained repulsive up until contact, and no van der Waals attraction or adhesion was observed. Differences in the measured forces are explained by modification of the surface chemistry during cleaning, which alters the density of charged groups on the surface, but this cannot explain the observed disagreement with DLVO theory at high pH. PMID:24548170

  13. Laser Surface Modification of H13 Die Steel using Different Laser Spot Sizes

    NASA Astrophysics Data System (ADS)

    Aqida, S. N.; Naher, S.; Brabazon, D.

    2011-05-01

    This paper presents a laser surface modification process of AISI H13 tool steel using three sizes of laser spot with an aim to achieve reduced grain size and surface roughness. A Rofin DC-015 diffusion-cooled CO2 slab laser was used to process AISI H13 tool steel samples. Samples of 10 mm diameter were sectioned to 100 mm length in order to process a predefined circumferential area. The parameters selected for examination were laser peak power, overlap percentage and pulse repetition frequency (PRF). Metallographic study and image analysis were done to measure the grain size and the modified surface roughness was measured using two-dimensional surface profilometer. From metallographic study, the smallest grain sizes measured by laser modified surface were between 0.51 μm and 2.54 μm. The minimum surface roughness, Ra, recorded was 3.0 μm. This surface roughness of the modified die steel is similar to the surface quality of cast products. The grain size correlation with hardness followed the findings correlate with Hall-Petch relationship. The potential found for increase in surface hardness represents an important method to sustain tooling life.

  14. Surface charge effects in silicon wafer cleaning using surfactant-containing solutions

    NASA Astrophysics Data System (ADS)

    Jeon, Joong-Suck; Raghavan, Srini; Lowell, John K.; Wenner, Valerie

    1994-09-01

    The adsorption of an anionic and a cationic surfactant onto a silicon surface was investigated using the technique of ATR (Attenuated Total Reflection) FT-IR at pH values of 2.5 and 9.5. The surface charge development on silicon samples conditioned in these surfactant solutions was investigated using a SPV (Surface Photovoltage) technique. The adsorption of DTAB was found to be much higher at pH equals 9.5 than at pH equals 2.5. In contrast, adsorption of SDS was independent of pH. The surface charge of HF-last cleaned silicon p(100) wafers was almost the same as that of the as-received wafer. After conditioning in surfactant solutions, negatively charged silicon wafers showed an excess of positive charge except of silicon wafers conditioned in DTAB solution at pH equals 9.5. After a DI water rinsing step, the surface charge was returned to its original value.

  15. Laser-induced thermal desorption of aniline from silica surfaces

    NASA Astrophysics Data System (ADS)

    Voumard, Pierre; Zenobi, Renato

    1995-10-01

    A complete study on the energy partitioning upon laser-induced thermal desorption of aniline from silica surfaces was undertaken. The measurements include characterization of the aniline-quartz adsorption system using temperature-programmed desorption, the extrapolation of quasiequilibrium desorption temperatures to the regime of laser heating rates on the order of 109-1010 K/s by computational means, measurement of the kinetic energy distributions of desorbing aniline using a pump-probe method, and the determination of internal energies with resonance-enhanced multiphoton ionization spectroscopy. The measurements are compared to calculations of the surface temperature rise and the resulting desorption rates, based on a finite-difference mathematical description of pulsed laser heating. While the surface temperature of laser-heated silica reaches about 600-700 K at the time of desorption, the translational temperature of laser-desorbed aniline was measured to be Tkin=420±60 K, Tvib was 360±60 K, and Trot was 350±100 K. These results are discussed using different models for laser-induced thermal desorption from surfaces.

  16. Drag reduction on laser-patterned hierarchical superhydrophobic surfaces.

    PubMed

    Tanvir Ahmmed, K M; Kietzig, Anne-Marie

    2016-06-14

    Hierarchical laser-patterned surfaces were tested for their drag reduction abilities. A tertiary level of surface roughness which supports stable Cassie wetting was achieved on the patterned copper samples by laser-scanning multiple times. The laser-fabricated micro/nano structures sustained the shear stress in liquid flow. A rheometer setup was used to measure the drag reduction abilities in term of slip lengths on eight different samples. A considerable increase in slip length (111% on a grate sample) was observed on these surfaces compared to the slip length predictions from the theoretical and the experimental models for the non-hierarchical surfaces. The increase in slip lengths was correlated to the secondary level of roughness observed on the patterned samples. The drag reduction abilities of three different arrangements of the surface features were also compared: posts in a square lattice, parallel grates, and posts in a hexagonal lattice. Although the latter facilitates a stable Cassie state, it nevertheless resulted in a lower normalized slip length compared to the other two arrangements at a similar solid fraction. Furthermore, we coated the laser-patterned surfaces with a silane to test the effect of surface chemistry on drag reduction. While the contact angles were surprisingly similar for both the non-silanized and the silanized samples, we observed higher slip lengths on the latter, which we were able to explain by measuring the respective penetration depths of the liquid-vapour interface between surface features. PMID:27146256

  17. Drag reduction on laser-patterned hierarchical superhydrophobic surfaces.

    PubMed

    Tanvir Ahmmed, K M; Kietzig, Anne-Marie

    2016-06-14

    Hierarchical laser-patterned surfaces were tested for their drag reduction abilities. A tertiary level of surface roughness which supports stable Cassie wetting was achieved on the patterned copper samples by laser-scanning multiple times. The laser-fabricated micro/nano structures sustained the shear stress in liquid flow. A rheometer setup was used to measure the drag reduction abilities in term of slip lengths on eight different samples. A considerable increase in slip length (111% on a grate sample) was observed on these surfaces compared to the slip length predictions from the theoretical and the experimental models for the non-hierarchical surfaces. The increase in slip lengths was correlated to the secondary level of roughness observed on the patterned samples. The drag reduction abilities of three different arrangements of the surface features were also compared: posts in a square lattice, parallel grates, and posts in a hexagonal lattice. Although the latter facilitates a stable Cassie state, it nevertheless resulted in a lower normalized slip length compared to the other two arrangements at a similar solid fraction. Furthermore, we coated the laser-patterned surfaces with a silane to test the effect of surface chemistry on drag reduction. While the contact angles were surprisingly similar for both the non-silanized and the silanized samples, we observed higher slip lengths on the latter, which we were able to explain by measuring the respective penetration depths of the liquid-vapour interface between surface features.

  18. FOOD SURFACE TEXTURE MEASUREMENT USING REFLECTIVE CONFOCAL LASER SCANNING MICROSCOPY

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Confocal laser scanning microscopy (CLSM) was used in the reflection mode to characterize the surface texture (roughness) of sliced food surfaces. Sandpapers of grit size between 150 and 600 were used as the height reference to standardize the CLSM hardware settings. Sandpaper particle sizes were v...

  19. Low Temperature Silicon Surface Cleaning by HF Etching/Ultraviolet Ozone Cleaning (HF/UVOC) Method (II)—in situ UVOC

    NASA Astrophysics Data System (ADS)

    Kaneko, Tetsuya; Suemitsu, Maki; Miyamoto, Nobuo

    1989-12-01

    A new method to obtain clean silicon surfaces using a thermal treatment at as low as 700°C is proposed. The method consists of an ex situ treatment of HF dipping followed by a rinse in distilled, deionized water and in situ treatments of both UVOC under low oxygen pressure and annealing in vacuo. From the Arrhenius plot of the removal rate of the surface oxide, two mechanisms corresponding to a diffusion of the volatile product, SiO, and a reaction between oxygen and silicon are suggested to exist, with activation energies 3.7 eV and 1.9 eV, respectively.

  20. In vitro study of the erbium:yttrium aluminum garnet laser cleaning of root canal by the use of shadow photography

    NASA Astrophysics Data System (ADS)

    Gregorčič, Peter; Lukač, Nejc; Možina, Janez; Jezeršek, Matija

    2016-01-01

    Erbium:yttrium aluminum garnet laser cleaning is a promising technique in endodontic treatment. In our in vitro study, we measured the vapor-bubble dynamics in the root canal by using shadow photography. The canal model was made of a plastic cutout placed between two transparent glass plates. An artificial smear layer was applied to the glass to study cleaning efficiency. In our results, no shock waves have been observed, since the pulp-chamber dimensions have been in the same range as the maximum diameter of the vapor bubble. This leads to the conclusion that shock waves are not the main cleaning mechanism within our model. However, the cleaning effects are also visible in the regions significantly below the bubble. Therefore, it can be concluded that fluid flow induced by the bubble's oscillations contributes significantly to the canal cleaning. We also proposed a simple theoretical model for cleaning efficiency and used it to evaluate the measured data.

  1. Designing Pulse Laser Surface Modification of H13 Steel Using Response Surface Method

    NASA Astrophysics Data System (ADS)

    Aqida, S. N.; Brabazon, D.; Naher, S.

    2011-01-01

    This paper presents a design of experiment (DOE) for laser surface modification process of AISI H13 tool steel in achieving the maximum hardness and minimum surface roughness at a range of modified layer depth. A Rofin DC-015 diffusion-cooled CO2 slab laser was used to process AISI H13 tool steel samples. Samples of 10 mm diameter were sectioned to 100 mm length in order to process a predefined circumferential area. The parameters selected for examination were laser peak power, overlap percentage and pulse repetition frequency (PRF). The response surface method with Box-Behnken design approach in Design Expert 7 software was used to design the H13 laser surface modification process. Metallographic study and image analysis were done to measure the modified layer depth. The modified surface roughness was measured using two-dimensional surface profilometer. The correlation of the three laser processing parameters and the modified surface properties was specified by plotting three-dimensional graph. The hardness properties were tested at 981 mN force. From metallographic study, the laser modified surface depth was between 37 μm and 150 μm. The average surface roughness recorded from the 2D profilometry was at a minimum value of 1.8 μm. The maximum hardness achieved was between 728 and 905 HV0.1. These findings are significant to modern development of hard coatings for wear resistant applications.

  2. Thermal and microstructural effects of nanosecond pulsed Nd:YAG laser irradiation on tooth root surface

    NASA Astrophysics Data System (ADS)

    Wilder-Smith, Petra B. B.; Arrastia-Jitosho, Anna-Marie A.; Grill, G.; Liaw, Lih-Huei L.; Berns, Michael W.

    1995-05-01

    Plaque, calculus and altered cementum removal by scaling and root planing is a fundamental procedure in periodontal treatment. However, the residual smear layer contains cytotoxic and inflammatory mediators which adversely affect healing. Chemical smear layer removal is also problematic. In previous investigations effective smear layer removal was achieved using long pulsed irradiation at 1.06 (mu) . However, laser irradiation was not adequate as an alternative to scaling and root planing procedures and concurrent temperature rises exceeded thermal thresholds for pulpal and periodontal safety. It was the aim of this study to determine whether nanosecond pulsed irradiation at 1.06 (mu) could be used as an alternative or an adjunct to scaling and root planing. Sixty freshly extracted teeth were divided as follows: 5 control, 5 root planed only, 25 irradiated only, 25 root planed and irradiated. Irradiation was performed at fluences of 0.5 - 2.7 J/cm2, total energy densities of 12 - 300 J/cm2, frequencies of 2 - 10 Hz using the Medlite (Continuum) laser. Irradiation-induced thermal events were recorded using a thermocouple within the root canal and a thermal camera to monitor surface temperatures. SEM demonstrated effective smear layer removal with minimal microstructural effects. Surface temperatures increased minimally (< 3 C) at all parameters, intrapulpal temperature rises remained below 4 C at 2 and 5 Hz, F < 0.5 J/cm2. Without prior scaling and root planing, laser effects did not provide an adequately clean root surface.

  3. Short range laser obstacle detector. [for surface vehicles using laser diode array

    NASA Technical Reports Server (NTRS)

    Kuriger, W. L. (Inventor)

    1973-01-01

    A short range obstacle detector for surface vehicles is described which utilizes an array of laser diodes. The diodes operate one at a time, with one diode for each adjacent azimuth sector. A vibrating mirror a short distance above the surface provides continuous scanning in elevation for all azimuth sectors. A diode laser is synchronized with the vibrating mirror to enable one diode laser to be fired, by pulses from a clock pulse source, a number of times during each elevation scan cycle. The time for a given pulse of light to be reflected from an obstacle and received is detected as a measure of range to the obstacle.

  4. Laser-induced selective copper plating of polypropylene surface

    NASA Astrophysics Data System (ADS)

    Ratautas, K.; Gedvilas, M.; Stankevičiene, I.; JagminienÄ--, A.; Norkus, E.; Li Pira, N.; Sinopoli, S.; Emanuele, U.; Račiukaitis, G.

    2016-03-01

    Laser writing for selective plating of electro-conductive lines for electronics has several significant advantages, compared to conventional printed circuit board technology. Firstly, this method is faster and cheaper at the prototyping stage. Secondly, material consumption is reduced, because it works selectively. However, the biggest merit of this method is potentiality to produce moulded interconnect device, enabling to create electronics on complex 3D surfaces, thus saving space, materials and cost of production. There are two basic techniques of laser writing for selective plating on plastics: the laser-induced selective activation (LISA) and laser direct structuring (LDS). In the LISA method, pure plastics without any dopant (filler) can be used. In the LDS method, special fillers are mixed in the polymer matrix. These fillers are activated during laser writing process, and, in the next processing step, the laser modified area can be selectively plated with metals. In this work, both methods of the laser writing for the selective plating of polymers were investigated and compared. For LDS approach, new material: polypropylene with carbon-based additives was tested using picosecond and nanosecond laser pulses. Different laser processing parameters (laser pulse energy, scanning speed, the number of scans, pulse durations, wavelength and overlapping of scanned lines) were applied in order to find out the optimal regime of activation. Areal selectivity tests showed a high plating resolution. The narrowest width of a copper-plated line was less than 23 μm. Finally, our material was applied to the prototype of the electronic circuit board on a 2D surface.

  5. Effect of cleaning and storage on quartz substrate adhesion and surface energy

    NASA Astrophysics Data System (ADS)

    Balachandran, Dave; John, Arun

    2014-04-01

    The force of adhesion of 50 nm diameter diamond-like carbon sphere probes to three quartz substrates was measured using an atomic force microscope. The force of adhesion was measured prior to cleaning, within 10 minutes after cleaning, after storage in an N2-purged cabinet, and after storage in an N2-purged vacuum oven. The evaluated cleaning recipes were SC1-like, SPM-like, and HF-based, each followed by ultra-pure deionized water (UPW) rinse and spin drying. The measurements were conducted in a Class 100 clean room at approximately 50% relative humidity. In addition, contact angle measurements were made on three additional quartz substrates using UPW before cleaning, after cleaning, and throughout N2 storage. The adhesion force increased after cleaning as compared to the pre-cleaned state, continued to increase until reaching a maximum after 5 days of N2 storage, and then decreased after 26 days for all three substrates. One substrate was then stored in a vacuum oven for 3 days, and the adhesion force decreased to 46% of the pre-cleaned state. The contact angle was reduced from over 30° before cleaning to 0° immediately after cleaning. During subsequent N2 storage, the contact angle increased to 5° or greater after 18 hours for the substrate cleaned with the HF-based recipe and after 15 days for the substrates cleaned by the SC1-like and SPM-like recipes.

  6. Electrically injected visible vertical cavity surface emitting laser diodes

    DOEpatents

    Schneider, Richard P.; Lott, James A.

    1994-01-01

    Visible laser light output from an electrically injected vertical cavity surface emitting laser (VSCEL) diode is enabled by the addition of phase-matching spacer layers on either side of the active region to form the optical cavity. The spacer layers comprise InAlP which act as charge carrier confinement means. Distributed Bragg reflector layers are formed on either side of the optical cavity to act as mirrors.

  7. Electrically injected visible vertical cavity surface emitting laser diodes

    DOEpatents

    Schneider, R.P.; Lott, J.A.

    1994-09-27

    Visible laser light output from an electrically injected vertical cavity surface emitting laser (VSCEL) diode is enabled by the addition of phase-matching spacer layers on either side of the active region to form the optical cavity. The spacer layers comprise InAlP which act as charge carrier confinement means. Distributed Bragg reflector layers are formed on either side of the optical cavity to act as mirrors. 5 figs.

  8. Surface separation investigation of ultrafast pulsed laser welding

    NASA Astrophysics Data System (ADS)

    Chen, Jianyong; Carter, Richard M.; Thomson, Robert R.; Hand, Duncan P.

    2016-03-01

    Techniques for joining materials, especially optical materials such as glass to structural materials such as metals, or to other optical materials, while maintaining their surface and optical properties are essential for a wide range of industrial applications. Adhesive bonding is commonly used but leads to many issues including optical surface contamination and outgassing. It is possible to generate welds using an ultra-short pulsed laser process, whereby two flat material surfaces are brought into close contact and the laser is focused through the optical material onto the interface. Highly localised melting and rapid resolidification form a strong bond between the two surfaces whilst avoiding significant heating of the surrounding material, which is important for joining materials with different thermal expansion coefficients. Previous reports on ultrafast laser welding have identified a requirement for the surface separation gap to be less than 500nm in order to avoid cracking or ablation at the interface. We have investigated techniques for increasing this gap (to reduce weld fit-up problems), and tested by bonding two surfaces with a weld-controlled gap. These gaps were generated either by a series of etched grooves on the surface of one of the substrates, or by using a cylindrical lens as a substrate. By careful optimisation of parameters such as laser power, process speed and focal position, we were able to demonstrate successful welding with a gap of up to 3μm.

  9. Femtosecond laser color marking stainless steel surface with different wavelengths

    NASA Astrophysics Data System (ADS)

    Li, Guoqiang; Li, Jiawen; Hu, Yanlei; Zhang, Chenchu; Li, Xiaohong; Chu, Jiaru; Huang, Wenhao

    2015-03-01

    The femtosecond laser color marking stainless steel surfaces with different incident wavelengths were investigated theoretically and experimentally. It indicates that the spectral regions of the colors firstly increase and then reduce with increasing spatial periods of the ripples induced by laser irradiation. Additionally, the colors are gradually changed from blue to red due to the elongation of the diffracted light wavelengths. As a result, the color effects are distinctly different. This study offers a new controllable parameter to produce diverse colors, which may find a wide range of applications in the laser color marking, art designing and so on.

  10. Issues Related to Cleaning Complex Geometry Surfaces with ODC-Free Solvents

    NASA Technical Reports Server (NTRS)

    Bradford, Blake F.; Wurth, Laura A.; Nayate, Pramod D.; McCool, Alex (Technical Monitor)

    2001-01-01

    Implementing ozone depleting chemicals (ODC)-free solvents into full-scale reusable solid rocket motor cleaning operations has presented problems due to the low vapor pressures of the solvents. Because of slow evaporation, solvent retention is a problem on porous substrates or on surfaces with irregular geometry, such as threaded boltholes, leak check ports, and nozzle backfill joints. The new solvents are being evaluated to replace 1,1,1-trichloroethane, which readily evaporates from these surfaces. Selection of the solvents to be evaluated on full-scale hardware was made based on results of subscale tests performed with flat surface coupons, which did not manifest the problem. Test efforts have been undertaken to address concerns with the slow-evaporating solvents. These concerns include effects on materials due to long-term exposure to solvent, potential migration from bolthole threads to seal surfaces, and effects on bolt loading due to solvent retention in threads. Tests performed to date have verified that retained solvent does not affect materials or hardware performance. Process modifications have also been developed to assist drying, and these can be implemented if additional drying becomes necessary.

  11. Metastable-atom deexcitation spectroscopy of clean and Ag-adsorbed Si (111) surfaces

    NASA Astrophysics Data System (ADS)

    Nishigaki, S.; Takao, K.; Yamada, T.; Arimoto, M.; Komatsu, T.

    1985-07-01

    Electron energy spectra upon incidence of He ∗ metastables on a clean Si(111)7 × 7 surface are obtained, which demonstrate the operation of the surface Penning ionization mechanism for the metastable-atom deexcitation (MD). Dangling bond orbitals are detected at about -0.5 and -1.5 eV below EF in the MD spectra. They are compared with previous UPS results. The adsorption process of Ag on Si(111) is studied by MDS and AES. In a MD spectrum for a Ag-deposited surface at room temperature with θ = {2}/{3} a peak appears at -5.2 below EF which belongs to Ag 4d orbitals. For a surface with the 3× 3 structure (deposited at 300°C with θ = {2}/{3}), however, the intensity of the Ag 4d peak is rather weak and its energy shifts by about -0.4 eV from the room-temperature value. These results support the embedded-Ag model for the Si(111) 3Ag structure.

  12. Amino acid conjugated self assembling molecules for enhancing surface wettability of fiber laser treated titanium surfaces

    NASA Astrophysics Data System (ADS)

    Akkan, Cagri K.; Hür, Deniz; Uzun, Lokman; Garipcan, Bora

    2016-03-01

    Surface wetting properties of implants are one of the most critical parameter, which determine the interaction of proteins and cells with the implant surface. In this regards, acid etching and sand blasting are the mostly used methods at surface modification of Titanium (Ti) for enhanced surface wettability. Besides, these kinds of modifications may cause a conflict whether the surface wettability is influenced by the process related surface contaminations or by the surface roughness. In contrast, lasers might be an option for the alteration of surface wetting properties via supporting micro and/or nano surface topographies while preventing surface chemical contaminations. In this work, we focused on two steps of surface processing approaches of Ti surface: physical and chemical modifications. Herein, we hierarchically structured Ti surfaces by using microsecond modulated pulsed fiber laser. Subsequently, laser structured and non-structured Ti surfaces were further modified with novel histidine and leucine Amino Acid conjugated Self-Assembled Molecules (His1-SAMs2 and Leu3-SAMs) to alter the surface wettability by introducing biologically hydrophilic and hydrophobic groups. Modification of Ti surfaces with His-SAMs and Leu-SAMs ended up with stable wetting properties when compared to non-modified surfaces after 7 days which may enhances the cell-surface interaction.

  13. Digital processing of SEM images for the assessment of evaluation indexes of cleaning interventions on Pentelic marble surfaces

    SciTech Connect

    Moropoulou, A. Delegou, E.T.; Vlahakis, V.; Karaviti, E.

    2007-11-15

    In this work, digital processing of scanning-electron-microscopy images utilized to assess cleaning interventions applied on the Pentelic marble surfaces of the National Archaeological Museum and National Library in Athens, Greece. Beside mineralogical and chemical characterization that took place by scanning-electron-microscopy with Energy Dispersive X-ray Spectroscopy, the image-analysis program EDGE was applied for estimating three evaluation indexes of the marble micro-structure. The EDGE program was developed by the U.S. Geological Survey for the evaluation of cleaning interventions applied on Philadelphia City Hall. This computer program analyzes scanning-electron-microscopy images of stone specimens cut in cross-section for measuring the fractal dimension of the exposed surfaces, the stone near-surface fracture density, the shape factor (a surface roughness factor) and the friability index which represents the physico-chemical and physico-mechanical stability of the stone surface. The results indicated that the evaluation of the marble surface micro-structure before and after cleaning is achieved by the suggested indexes, while the performance of cleaning interventions on the marble surfaces can be assessed.

  14. Artefacts in RBS analysis of laser treated surfaces

    NASA Astrophysics Data System (ADS)

    Kuldeep; Jain, Animesh K.

    1986-04-01

    Laser treatment of deposited films often result in globules on the surface which may influence the solute depth profiles, as measured by Rutherford backscattering spectrometry (RBS). We show that the globules generally have poor adhesion to the substrate and can be easily removed using techniques commonly employed for testing adhesion of thin films, such as a scotch tape test, or mild abrasion test using a cotton bud or tip of a soft wooden piece. The effectiveness of this approach is demonstrated for Zn films on Al (treated with a 12 ns fwhm Nd: glass laser pulse) and Sb films on Al (treated with a 100 ns fwhm CO 2 laser pulse). The solute depth profiles, both before and after removal of globules from the laser treated surfaces, have been measured by employing RBS of He + ions and dramatic differences between the two cases have been observed. Laser treated surfaces are also characterized by optical microscopy and the topography is correlated with the RBS depth profiles. Results are presented for laser heating and liquid phase diffusion analysis of the solute depth profiles obtained after scotch tape and abrasion tests.

  15. Multifunctional gratings for surface-emitting lasers: design and implementation.

    PubMed

    Modh, Peter; Backlund, Johan; Bengtsson, Jörgen; Larsson, Anders; Shimada, Naoyuki; Suhara, Toshiaki

    2003-08-20

    We experimentally demonstrate the use of two different multifunctional grating couplers in surface-emitting lasers for improved beam quality and advanced beam profiles. The lasers used for the demonstration are grating-based unstable resonator lasers, each with a grating coupler for surface emission and beam shaping. The new design method, described in detail, allows for simultaneous optimization of arbitrary feedback and outcoupling characteristics of the grating coupler. The first coupler is designed to reduce feedback to the resonator that would otherwise disturb the operation of the laser and lower the beam quality and to produce an output beam focused to four spots. The second coupler is designed to provide the feedback needed to support the unstable resonator, eliminating one feedback grating, and simultaneously focus the output beam to a single spot. As far as we know, this is the first time such multifunctional couplers are used in grating-coupled surface-emitting lasers. The couplers provide near-diffraction-limited spots that are a considerable improvement compared with previous lasers with no feedback control in the couplers. PMID:12952329

  16. Laser-heating-induced displacement of surfactants on the water surface.

    PubMed

    Backus, Ellen H G; Bonn, Daniel; Cantin, Sophie; Roke, Sylvie; Bonn, Mischa

    2012-03-01

    We report a combined vibrational sum-frequency generation (SFG) spectroscopy, Brewster angle microscopy (BAM), and ellipsometry study of different surfactants on water as a function of surfactant density. Vibrational SFG spectra of surfactants on the water surface in a Langmuir trough have been measured in both the surfactant CH and the water OH stretch regions. At low densities, the SFG signal generated at the surface in the presence of the surfactant is indistinguishable from the SFG signal generated at the clean water-air interface. When the surfactant density increases, i.e., upon compressing the monolayer, a very sudden increase in the SFG signal in both the CH and OH spectral regions is observed. For higher laser fluences, this stepwise increase occurs at increasingly higher surfactant densities. Since BAM shows that surfactant molecules are clearly present at these low densities, we conclude that at low surfactant density the laser beam displaces relatively high-density domains with surfactants in the liquid expanded phase out of the region of the laser focus. This is a consequence of the thermal gradient induced by local heating of the water phase with the monolayer on top due to repetitive laser excitation at 1 kHz. It can be circumvented by using a rotating trough. In this manner, the sampled surface area can be refreshed, allowing artifact-free vibrational SFG spectra to be measured down to the very lowest surfactant densities. In ellipsometry experiments, a similar step can be noticed, which, however, is of a different nature; i.e., it is not related to heating (the laser fluence is very low and the light nonresonant) but to a molecular transition. The occurrence of the step in ellipsometry as a function of area per molecule depends critically on the preparation of the monolayer. By giving the molecules time and space to relax during the preparation of the monolayer, this step could also be eliminated.

  17. Optodynamics: dynamic aspects of laser beam-surface interaction

    NASA Astrophysics Data System (ADS)

    Možina, J.; Diaci, J.

    2012-05-01

    This paper presents a synthesis of the results of our original research in the area of laser-material interaction and pulsed laser material processing with a special emphasis on the dynamic aspects of laser beam-surface interaction, which include the links between the laser material removal and the resulting material motion. In view of laser material processing, a laser beam is not only considered as a tool but also as a generator of information about the material transformation. The information is retained and conveyed by different kinds of optically induced mechanical waves. Several generation/detection schemes have been developed to extract this information, especially in the field of non-destructive material evaluation. Blast and acoustic waves, which propagate in the air surrounding the work-piece, have been studied using microphone detection as well as various setups of the laser beam deflection probe. Stress waves propagating through the work-piece have been studied using piezoelectric transducers and laser interferometers.

  18. Control of physical properties on solid surface via laser processing

    NASA Astrophysics Data System (ADS)

    Yonemoto, Yukihiro; Nishimura, Akihiko

    2012-07-01

    In a safety operation of a nuclear power plant, vapor conditions such as a droplet or liquid membrane toward a solid surface of a heat exchanger and reactor vessel is important. In the present study, focusing on the droplet, the wettability on solid surface and surface free energy of solid are evaluated. In addition, wettability on a metal plate fabricated by laser processing is also considered for the nuclear engineering application.

  19. Pulsed laser stereophotography of plasmas and dynamically moving surfaces

    SciTech Connect

    Paisley, D.L.

    1987-01-01

    A pulsed laser is used as a light source for illuminating the surface of a dynamic event of less than or equal to1 mm/sup 2/ moving at >3 mm/..mu..s. At a predetermined time during the dynamic action, a stereo camera is used to record a pair of images of the dynamically moving surface. The stereoimage pair can be quantified for surface contour. 3 refs., 8 figs.

  20. Transfer of Salmonella Enteritidis to four types of surfaces after cleaning procedures and cross-contamination to tomatoes.

    PubMed

    Soares, Vanessa Mendonça; Pereira, Juliano Gonçalves; Viana, Cibeli; Izidoro, Thiago Braga; Bersot, Luciano dos Santos; Pinto, José Paes de Almeida Nogueira

    2012-06-01

    The objectives of the present study were to evaluate the spread of Salmonella Enteritidis to different cutting boards (wood, triclosan-treated plastic, glass, and stainless steel) from contaminated poultry skin (5 log CFU/g) and then to tomatoes and to analyze the effect of different protocols used to clean these surfaces to control contamination. The following procedures were simulated: (1) no cleaning after handling contaminated poultry skin; (2) rinsing in running water; (3) cleaning with dish soap and mechanical scrubbing; and (4) cleaning with dish soap and mechanical scrubbing, followed by disinfection with hypochlorite. The pathogen was recovered from all surfaces following procedure 1, with counts ranging from 1.90 to 2.80 log, as well as from the tomatoes handled on it. Reduced numbers of S. Enteritidis were recovered using the other procedures, both from the surfaces and from the tomatoes. Counts were undetectable after procedure 4. From all surfaces evaluated, wood was the most difficult to clean, and stainless steel was the easiest. The use of hypochlorite as a disinfecting agent helped to reduce cross-contamination. PMID:22365360

  1. Achieving clean epitaxial graphene surfaces suitable for device applications by improved lithographic process

    SciTech Connect

    Nath, A. Rao, M. V.; Koehler, A. D.; Jernigan, G. G.; Wheeler, V. D.; Hite, J. K.; Hernández, S. C.; Robinson, Z. R.; Myers-Ward, R. L.; Eddy, C. R.; Gaskill, D. K.; Garces, N. Y.

    2014-06-02

    It is well-known that the performance of graphene electronic devices is often limited by extrinsic scattering related to resist residue from transfer, lithography, and other processes. Here, we report a polymer-assisted fabrication procedure that produces a clean graphene surface following device fabrication by a standard lithography process. The effectiveness of this improved lithography process is demonstrated by examining the temperature dependence of epitaxial graphene-metal contact resistance using the transfer length method for Ti/Au (10 nm/50 nm) metallization. The Landauer-Buttiker model was used to explain carrier transport at the graphene-metal interface as a function of temperature. At room temperature, a contact resistance of 140 Ω-μm was obtained after a thermal anneal at 523 K for 2 hr under vacuum, which is comparable to state-of-the-art values.

  2. Multibeam echosounder data cleaning through a hierarchic adaptive and robust local surfacing

    NASA Astrophysics Data System (ADS)

    Debese, Nathalie; Moitié, Rodéric; Seube, Nicolas

    2012-09-01

    Multibeam echo sounders (MBES) datasets generally contain sporadic outlier points. The huge volumes of MBES datasets in a hydrographic framework require the use of semi-automatic techniques. In very shallow waters depth, data cleaning becomes a challenging task when potential dangers to navigation have to be carefully checked. The aim of our paper is to attempt this goal by combining two well-known techniques. The seafloor is constructed as an assemblage of surface elements with the help of a robust statistical approach. The local parameters model is a priori chosen, its scale is driven through a quadtree descending approach using subdivision rules based on both statistical and spatio-temporal inferences. Our multi resolution approach provides, with the algorithm outputs, a classification map that notes areas of concern.

  3. Residual viral and bacterial contamination of surfaces after cleaning and disinfection.

    PubMed

    Tuladhar, Era; Hazeleger, Wilma C; Koopmans, Marion; Zwietering, Marcel H; Beumer, Rijkelt R; Duizer, Erwin

    2012-11-01

    Environmental surfaces contaminated with pathogens can be sources of indirect transmission, and cleaning and disinfection are common interventions focused on reducing contamination levels. We determined the efficacy of cleaning and disinfection procedures for reducing contamination by noroviruses, rotavirus, poliovirus, parechovirus, adenovirus, influenza virus, Staphylococcus aureus, and Salmonella enterica from artificially contaminated stainless steel surfaces. After a single wipe with water, liquid soap, or 250-ppm free chlorine solution, the numbers of infective viruses and bacteria were reduced by 1 log(10) for poliovirus and close to 4 log(10) for influenza virus. There was no significant difference in residual contamination levels after wiping with water, liquid soap, or 250-ppm chlorine solution. When a single wipe with liquid soap was followed by a second wipe using 250- or 1,000-ppm chlorine, an extra 1- to 3-log(10) reduction was achieved, and except for rotavirus and norovirus genogroup I, no significant additional effect of 1,000 ppm compared to 250 ppm was found. A reduced correlation between reduction in PCR units (PCRU) and reduction in infectious particles suggests that at least part of the reduction achieved in the second step is due to inactivation instead of removal alone. We used data on infectious doses and transfer efficiencies to estimate a target level to which the residual contamination should be reduced and found that a single wipe with liquid soap followed by a wipe with 250-ppm free chlorine solution was sufficient to reduce the residual contamination to below the target level for most of the pathogens tested. PMID:22941071

  4. Study of Surface Cleaning Methods and Pyrolysis Temperature on Nano-Structured Carbon Films using X-ray Photoelectron Spectroscopy

    SciTech Connect

    Kerber, Pranita B.; Porter, Lisa M.; McCullough, L. A.; Kowalewski, Tomasz; Engelhard, Mark H.; Baer, Donald R.

    2012-10-12

    Nanostructured carbon (ns-C) films fabricated by stabilization and pyrolysis of di-block copolymers are of interest for a variety of electrical/electronic applications due to their chemical inertness, high-temperature insensitivity, very high surface area, and tunable electrical resistivity over a wide range [Kulkarni et al., Synth. Met. 159, (2009) 177]. Because of their high porosity and associated high specific surface area, controlled surface cleaning studies are important for fabricating electronic devices from these films. In this study, quantification of surface composition and surface cleaning studies on ns-C films synthesized by carbonization of di-block copolymers of polyacrylonitrile-b-poly(n-butyl acrylate) (PAN-b-PBA) at two different temperatures were carried out. X-ray photoelectron spectroscopy was used for elemental analysis and to determine the efficacy of various surface cleaning methods for ns-C films and to examine the polymer residues in the films. The in-situ surface cleaning methods included: HF vapor treatment, vacuum annealing, and exposure to UV-ozone. Quantitative analysis of high-resolution XPS scans showed 11 at. % of nitrogen present in the films pyrolyzed at 600 °C, suggesting incomplete denitrogenation of the copolymer films. The nitrogen atomic concentration reduced significantly for films pyrolyzed at 900 °C confirming extensive denitrogenation at that temperature. Furthermore, quantitative analysis of nitrogen sub-peaks indicated higher loss of nitrogen atoms residing at the edge of graphitic clusters relative to that of nitrogen atoms within the graphitic cluster, suggesting higher graphitization with increasing pyrolysis temperature. Of the surface cleaning methods investigated, in-situ annealing of the films at 300 °C for 40 min was found to be the most efficacious in removing adventitious carbon and oxygen impurities from the surface.

  5. Study of surface cleaning methods and pyrolysis temperatures on nanostructured carbon films using x-ray photoelectron spectroscopy

    SciTech Connect

    Kerber, Pranita; Porter, Lisa M.; McCullough, Lynne A.; Kowalewski, Tomasz; Engelhard, Mark; Baer, Donald

    2012-11-15

    Nanostructured carbon (ns-C) films fabricated by stabilization and pyrolysis of diblock copolymers are of interest for a variety of electrical/electronic applications due to their chemical inertness, high-temperature insensitivity, very high surface area, and tunable electrical resistivity over a wide range [Kulkarni et al., Synth. Met. 159, 177 (2009)]. Because of their high porosity and associated high specific surface area, controlled surface cleaning studies are important for fabricating electronic devices from these films. In this study, quantification of surface composition and surface cleaning studies on ns-C films synthesized by carbonization of diblock copolymers of polyacrylonitrile-b-poly(n-butyl acrylate) at two different temperatures were carried out. X-ray photoelectron spectroscopy was used for elemental analysis and to determine the efficacy of various surface cleaning methods for ns-C films and to examine the polymer residues in the films. The in-situ surface cleaning methods included HF vapor treatment, vacuum annealing, and exposure to UV-ozone. Quantitative analysis of high-resolution XPS scans showed 11 at. % nitrogen was present in the films pyrolyzed at 600 Degree-Sign C, suggesting incomplete denitrogenation of the copolymer films. The nitrogen atomic concentration decreased significantly for films pyrolyzed at 900 Degree-Sign C confirming extensive denitrogenation at that temperature. Furthermore, quantitative analysis of nitrogen subpeaks indicated higher loss of nitrogen atoms residing at the edge of graphitic clusters relative to that of nitrogen atoms within the graphitic clusters, suggesting higher graphitization with increasing pyrolysis temperature. Of the surface cleaning methods investigated, in-situ annealing of the films at 300 Degree-Sign C for 40 min was found to be the most efficacious in removing adventitious carbon and oxygen impurities from the surface.

  6. The shaped critical surface in high intensity laser plasma interactions

    SciTech Connect

    Schumacher, D. W.; Kemp, G. E.; Link, A.; Freeman, R. R.; Van Woerkom, L. D.

    2011-01-15

    This paper describes an investigation of the properties of the relativistic critical surface in a high intensity laser-plasma interaction, specifically the spatial morphology of the surface and its effect upon the divergence of the reflected light. The particle-in-cell code LSP running in two dimensions (2d3v) was used to model the formation of the critical surface and to show that it resides at a varying depth into the material that is dependent on both the intensity radial dependence of the laser focus as well as the shape of the longitudinal vacuum-material interface. The result is a shaped 'mirror' surface that creates a reflected beam with phase and amplitude information informed by the extent of the preplasma present before the intense laser pulse arrived. A robust, highly effective means of experimentally determining the preplasma conditions for any high intensity laser-matter interaction is proposed using this effect. The important physics is elucidated with a simplified model that, within reasonable intensity bounds, recasts the effect of the complex laser-plasma interaction on the reflected beam into a standard Gaussian optics calculation.

  7. Value added cleaning and disinfection of the root canal: laser-activated irrigation and laser-induced photoporation

    NASA Astrophysics Data System (ADS)

    De Moor, Roeland J. G.; Meire, Maarten A.

    2016-03-01

    Among present-day marketed systems ultrasonic activation appears to be the best way to activate and potentiate endodontic irrigants. An alternative for ultrasonic activation of irrigants is laser activated irrigation (LAI) or photoninitiated acoustic streaming. Based on present-day research it appears that LAI (especially with Erbium lasers) can be more efficient for debris removal out of root canals and interaction with the endodontic biofilms thanks to the induction of specific cavitation phenomena and acoustic streaming. Other wavelengths are now explored to be used for LAI. Another way to interact with biofilms is to rely on laser-induced photoporation in combination with gold nanoparticles ( AuNPs). The latter is an alternative physical method for delivering macromolecules in cells. Nanosized membrane pores can be created upon pulsed laser illumination. Depending on the laser energy, pores are created through either direct heating of the AuNPs or by vapour nanobubbles that can emerge around the AuNPs.

  8. Cleaning of endodontic root canal by ultrasonics and Nd:YAG laser beam with fiber optic delivery: scanning electron microscopy, endoscopic and microradiographic analysis

    NASA Astrophysics Data System (ADS)

    Berna, Norberto; Melis, Marco; Benvenuti, Alessandro; Tosto, Sebastiano; Pierdominici, Fabrizio

    1997-05-01

    12 teeth have been extracted and treated 'in vitro' by ultrasonics and Nd:YAG pulsed laser with fiber optic delivery to compare the cleaning efficiency of the root canal. The optic fiber was equipped with a water-air coaxial cooling system. The ultrasonic device was equipped with a 3 percent NaCl solution douche system. The samples have been prepared according to the technical specifications of the suppliers of laser and ultrasonics and observed by an endodontic endoscope. Cross sections of the samples have been utilized for microradiographic investigations and scanning electron microscopy observations. Local melting has been observed after laser irradiation.Also, vitrification preferentially occurred in the apical zones. The occurrence of vitrification was found strongly dependent on the translation velocity of the laser beam inside the root canal. The laser beam has shown a cleaning efficiency greater than that obtained by ultrasonic procedure.

  9. Characterization of an Effective Cleaning Procedure for Aluminum Alloys: Surface Enhanced Raman Spectroscopy and Zeta Potential Analysis

    SciTech Connect

    Cherepy, N J; Shen, T H; Esposito, A P; Tillotson, T M

    2004-06-02

    We have developed a cleaning procedure for aluminum alloys for effective minimization of surface-adsorbed sub-micron particles and non-volatile residue. The procedure consists of a phosphoric acid etch followed by an alkaline detergent wash. To better understand the mechanism whereby this procedure reduces surface contaminants, we characterized the aluminum surface as a function of cleaning step using Surface Enhanced Raman Spectroscopy (SERS). SERS indicates that phosphoric acid etching re-establishes a surface oxide of different characteristics, including deposition of phosphate and increased hydration, while the subsequent alkaline detergent wash appears to remove the phosphate and modify the new surface oxide, possibly leading to a more compact surface oxide. We also studied the zeta potential of <5 micron pure aluminum and aluminum alloy 6061-T6 particles to determine how surface electrostatics may be affected during the cleaning process. The particles show a decrease in the magnitude of their zeta potential in the presence of detergent, and this effect is most pronounced for particles that have been etched with phosphoric acid. This reduction in magnitude of the surface attractive potential is in agreement with our observation that the phosphoric acid etch followed by detergent wash results in a decrease in surface-adsorbed sub-micron particulates.

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

    SciTech Connect

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

    2015-09-15

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

  11. Tuning 3D topography on biomimetic surface for efficient self-cleaning and microfluidic manipulation

    NASA Astrophysics Data System (ADS)

    Guan, Wei-Sheng; Huang, Han-Xiong; Chen, An-Fu

    2015-03-01

    Currently, micro-/nanotopography on polymeric replica is generally limited to 2D when a mechanical demolding approach is applied. In this work, one-step replication of bio-inspired 3D topography is achieved using microinjection compression molding with novel dual-layer molds. Using a proposed flexible template, the replica topography and wettability are highly tunable during molding. Moreover, dual-scale topography on the mold is developed by coating the micropatterned insert with submicron silica particles. Contact angle and roll-off angle measurements indicate the lotus leaf, rose petal and rice leaf effects on biomimetic surfaces. Among the three kinds of surfaces, the petal-inspired surface possesses the superior performance in self-cleaning submicron contaminants and mechanical robustness, which is highly correlated to the low roughness-induced adhesive superhydrophobicity and the absence of fragile submicron-/nanostructure, respectively. Furthermore, a multi-layer mold structure is proposed for fabricating the open microfluidic devices. The embedment of the hydrophilic and hydrophobic silica particles in the microstructured open channel and the hydrophobic silica particles in the background area during replication renders the wettability contrast sharp, realizing the self-driven flow of microfluid confined within the open microchannel.

  12. Work of Adhesion of a Sessile Drop to a Clean Surface.

    PubMed

    Schroder

    1999-05-15

    According to the Young-Dupré equation, as interpreted by Bangham and Razouk, the work of adhesion of a sessile drop to a smooth solid surface is given by WS(V)L = gammaL (1 + cos θ), where θ is the equilibrium contact angle measured at equilibrium of the system with the saturated vapor of the liquid, and WS(V)L is the work of adhesion of that drop to the solid surface which is in equilibrium with that vapor and may contain an adlayer of the vapor. For calculation of WSL, the work of adhesion of a sessile drop to a clean solid surface, the equation WSL = gammaL (1 + cos θ) + Pie is generally used (although Bangham and Razouk never proposed it). Pie is the negative of the free energy of formation of the adlayer, sometimes called the spreading pressure. In the present work it is shown that the latter equation cannot be accurate. Copyright 1999 Academic Press.

  13. Preliminary surface-emitting laser logic device evaluation

    NASA Astrophysics Data System (ADS)

    Libby, S. I.; Parker, M. A.; Olbright, G. R.; Swanson, P. D.

    1993-03-01

    This report discusses the evaluation of a monolithically integrated heterojunction phototransistor and vertical-cavity surface-emitting laser, designated the surface-Emitting Laser Logic device (CELL). Included is a discussion of the device structure and theory of operation, test procedures, results, and conclusions. Also presented is the CELL's opto-electronic input/output characteristics which includes spectral analysis, characteristic emitted light versus current and current versus voltage curves, input wavelength tolerance, output wavelength sensitivity to bias current, and insensitivity to input wavelength and power within a specified range.

  14. Vertical-cavity surface-emitting laser device

    DOEpatents

    Hadley, G. Ronald; Lear, Kevin L.; Awyoung, Adelbert; Choquette, Kent D.

    1999-01-01

    A vertical-cavity surface-emitting laser device. The vertical-cavity surface-emitting laser (VCSEL) device comprises one or more VCSELs with each VCSEL having a mode-control region thereabout, with the mode-control region forming an optical cavity with an effective cavity length different from the effective cavity length within each VCSEL. Embodiments of the present invention can be formed as single VCSELs and as one- or two-dimensional arrays of VCSELs, with either an index-guided mode of operation or an index anti-guided mode of operation being defined by a sign of the difference in the two effective cavity lengths.

  15. Surface Structuring of CFRP by using Modern Excimer Laser Sources

    NASA Astrophysics Data System (ADS)

    Fischer, F.; Kreling, S.; Dilger, K.

    High demands for lightweight construction can be attained by the use of carbon fiber-reinforced plastics (CFRP) including one major challenge: the joining technology. Adhesive bonding may allow an increased utilization of the lightweight potential of CFRP. But this technology requires a surface pre-treatment because of residues of release agents. This paper describes surface pre-treatment of CFRP specimens by using modern excimer laser and the mechanical tests that compare the achieved strength to manually abraded ones. The laser process is suitable for achieving cohesive failure within the adhesive and bond strengths in the magnitude of the abraded specimen.

  16. EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Transient deformation of the surface of a thermocapillary liquid by laser heating

    NASA Astrophysics Data System (ADS)

    Rozniakowski, K.

    1995-02-01

    Deformation self-focusing of a laser beam (0.6328 μm, 5 mW) on the surface of a strongly absorbing viscous liquid was studied experimentally. It was found that the approach described can be used to evaluate the surface tension.

  17. Surface Change Detection Using Large Footprint Laser Altimetry

    NASA Technical Reports Server (NTRS)

    Blair, J. Bryan; Hofton, Michelle A.; Smith, David E. (Technical Monitor)

    2000-01-01

    Laser altimeters provide a precise and accurate method for mapping topography at fine horizontal and vertical scales. A laser altimeter provides range by measuring the roundtrip flight time of a short pulse of laser light from the laser altimeter instrument to the target surface. The range is then combined with laser beam pointing knowledge and absolute position knowledge to provide an absolute measurement of the surface topography. Newer generations of laser altimeters measure the range by recording the shape and time of the outgoing and received laser pulses. The shape of the return pulse can also provide unique information about the vertical structure of material such as vegetation within each laser footprint. Distortion of the return pulse is caused by the time-distributed reflections adding together and representing the vertical distribution of surfaces within the footprint. Larger footprints (10 - 100m in diameter) can support numerous target surfaces and thus provide the potential for producing complex return pulses. Interpreting the return pulse from laser altimeters has evolved from simple timing between thresholds, range-walk corrections, constant-fraction discriminators, and multi-stop time interval units to actual recording of the time varying return pulse intensity - the return waveform. Interpreting the waveform can be as simple as digitally thresholding the return pulse, calculating a centroid, to fitting one or more gaussian pulse-shapes to the signal. What we present here is a new technique for using the raw recorded return pulse as a raw observation to detect centimeter-level vertical topographic change using large footprint airborne and spaceborne laser altimetry. We use the correlation of waveforms from coincident footprints as an indication of the similarity in structure of the waveforms from epoch to epoch, and assume that low correlation is an indicator of vertical structure or elevation change. Thus, using vertically and horizontally

  18. Analysis and Design of Vertical Cavity Surface Emitting Lasers

    NASA Astrophysics Data System (ADS)

    Yu, S. F.

    2003-08-01

    A practical, hands-on guidebook for the efficient modeling of VCSELs Vertical Cavity Surface Emitting Lasers (VCSELs) are a unique type of semiconductor laser whose optical output is vertically emitted from the surface as opposed to conventional edge-emitting semiconductor lasers. Complex in design and expensive to produce, VCSELs nevertheless represent an already widely used laser technology that promises to have even more significant applications in the future. Although the research has accelerated, there have been relatively few books written on this important topic. Analysis and Design of Vertical Cavity Surface Emitting Lasers seeks to encapsulate this growing body of knowledge into a single, comprehensive reference that will be of equal value for both professionals and academics in the field. The author, a recognized expert in the field of VCSELs, attempts to clarify often conflicting assumptions in order to help readers achieve the simplest and most efficient VCSEL models for any given problem. Highlights of the text include: * A clear and comprehensive theoretical treatment of VCSELs * Detailed derivations for understanding the operational principles of VCSELs * Mathematical models for the investigation of electrical, optical, and thermal properties of VCSELs * Case studies on the mathematical modeling of VCSELs and the implementation of simulation programs

  19. Modification of Surface Energy via Direct Laser Ablative Surface Patterning

    NASA Technical Reports Server (NTRS)

    Wohl, Christopher J., Jr. (Inventor); Belcher, Marcus A. (Inventor); Connell, John W. (Inventor); Hopkins, John W. (Inventor)

    2015-01-01

    Surface energy of a substrate is changed without the need for any template, mask, or additional coating medium applied to the substrate. At least one beam of energy directly ablates a substrate surface to form a predefined topographical pattern at the surface. Each beam of energy has a width of approximately 25 micrometers and an energy of approximately 1-500 microJoules. Features in the topographical pattern have a width of approximately 1-500 micrometers and a height of approximately 1.4-100 micrometers.

  20. Surface measuring technique. [using a laser to scan the surface of a reflector

    NASA Technical Reports Server (NTRS)

    Spiers, R. B., Jr.

    1980-01-01

    Measurement of the surface contour of a large electrostatically formed concave reflector using a modified Foucault or knife edge test is described. The curve of the actual electrostatically formed reflector surface is compared to a curve representing a reference sphere. Measurements of surface slope and deviation are calculated every 15 cm along the reflector's horizontal and vertical diameters. Characterization of surface roughness on a small scale compared to the laser spot size at the reflector are obtained from the increased laser spot size at a distant projection screen.

  1. Laser Polishing: Green Path to Improved Accelerator Surfaces

    SciTech Connect

    Kelley, Michael

    2015-10-06

    We pursued three paths toward reducing the initial cost and operating expense of particle accelerators. First, we investigated laser surface melting as an alternative to the present cavity processing approach using noxious chemicals. We successfully demonstrated a process that can be scaled up and defined the path to do so. Second, we sought to develop tailored laser pulsing as a way to simulate the thermal fatigue environment responsible for damaging accelerator components. Though the first three steps along the path were successfully accomplished, the final segment depended on collaborators with unique facilities, whose program was terminated. The third segment aimed to acquire a fundamental understanding of the widely used chemical process that yields the rough surfaces smoothed by laser melting. We found that the roughness is an inherent and unavoidable outcome that limits the performance of components processed thusly.

  2. Tailored surface modification by ion implantation and laser treatment

    NASA Astrophysics Data System (ADS)

    Picraux, S. T.; Pope, L. E.

    1984-11-01

    Techniques and applications of ion- and laser-beam treatment of surface and near surface materials to control the composition and microstructure are explored. The processes are especially useful in miniaturized electronic components with large surface/volume ratios. Laser beams permit selective, extremely short interval high energy heating of specific molecules in surfaces and studies of transient and metastable states that are otherwise unattainable. The applications affect the wear, friction, hardness, adhesion, fatigue, toughness, ductility, corrosion resistance, and electromagnetic properties of the materials. Beam treatments have been successfully applied to polymers, ceramics, metals, and microprocessors, often causing new performance characteristics to appear. The techniques are noted to relax the usual constraints of thermal equilibrium and thereby increase the understanding of materials.

  3. Analysis of Surface Roughness at Overlapping Laser Shock Peening

    NASA Astrophysics Data System (ADS)

    Dai, F. Z.; Zhang, Z. D.; Zhou, J. Z.; Lu, J. Z.; Zhang, Y. K.

    2016-02-01

    The overlapping effects on surface roughness are studied when samples are treated by laser shock peening (LSP). Surface roughness of overlapped circular laser spot is calculated by ISO 25178 height parameters. The usually used overlapping styles namely isosceles-right-triangle-style (AAP) and equilateral-triangle-style (AAA) are carefully investigated when the overlapping degree in x-axis (ηx) is below 50%. Surface roughness of isosceles-right-triangle-style attains its minimum value at ηx of 29.3%, and attains its maximum value at ηx of 43.6%. Surface roughness of equilateral-triangle-style attains its minimum value at ηx of 42.3%, and attains its maximum value at ηx of 32%. Experimental results are well consistent with theoretical analysis.

  4. Laser polishing for topography management of accelerator cavity surfaces

    SciTech Connect

    Zhao, Liang; Klopf, J. Mike; Reece, Charles E.; Kelley, Michael J.

    2015-07-20

    Improved energy efficiency and reduced cost are greatly desired for advanced particle accelerators. Progress toward both can be made by atomically-smoothing the interior surface of the niobium superconducting radiofrequency accelerator cavities at the machine's heart. Laser polishing offers a green alternative to the present aggressive chemical processes. We found parameters suitable for polishing niobium in all surface states expected for cavity production. As a result, careful measurement of the resulting surface chemistry revealed a modest thinning of the surface oxide layer, but no contamination.

  5. GaAs surface cleaning by thermal oxidation and sublimation in molecular-beam epitaxy

    NASA Astrophysics Data System (ADS)

    Saito, Junji; Nanbu, Kazuo; Ishikawa, Tomonori; Kondo, Kazuo

    1988-01-01

    GaAs surface cleaning by thermal oxidation and sublimation prior to molecular-beam-epitaxial growth has been investigated as a means of reducing the carrier depletion at the substrate and epitaxial layer interface. The carrier depletion between the substrate and epitaxial films, measured by a C-V carrier profiling technique, was shown to decrease significantly with an increase in the thickness of the thermal oxidation. The concentration of carbon contamination near the substrate-epitaxial interface was measured using secondary ion mass spectroscopy. The carbon concentration correlated very well with the carrier depletion. Therefore, the main origin of the carrier depletion is believed to be the carbon concentration of the initial growth surface. Based on these results, the thermal oxidation and sublimation of a semi-insulating GaAs substrate was successfully applied to improve the mobility and sheet concentration of the two-dimensional electron gas in selectively doped GaAs/N-Al0.3Ga0.7As heterostructures with very thin GaAs buffer layers.

  6. PRECISION CLEANING OF SEMICONDUCTOR SURFACES USING CARBON DIOXIDE-BASED FLUIDS

    SciTech Connect

    J. RUBIN; L. SIVILS; A. BUSNAINA

    1999-07-01

    The Los Alamos National Laboratory, on behalf of the Hewlett-Packard Company, is conducting tests of a closed-loop CO{sub 2}-based supercritical fluid process, known as Supercritical CO{sub 2} Resist Remover (SCORR). We have shown that this treatment process is effective in removing hard-baked, ion-implanted photoresists, and appears to be fully compatible with metallization systems. We are now performing experiments on production wafers to assess not only photoresist removal, but also residual surface contamination due to particulate and trace metals. Dense-phase (liquid or supercritical) CO{sub 2}, since it is non-polar, acts like an organic solvent and therefore has an inherently high volubility for organic compounds such as oils and greases. Also, dense CO{sub 2} has a low-viscosity and a low dielectric constant. Finally, CO{sub 2} in the liquid and supercritical fluid states can solubilize metal completing agents and surfactants. This combination of properties has interesting implications for the removal not only of organic films, but also trace metals and inorganic particulate. In this paper we discuss the possibility of using CO{sub 2} as a precision-cleaning solvent, with particular emphasis on semiconductor surfaces.

  7. Investigation of the Shockley surface state on clean and air-exposed Au (1 1 1)

    NASA Astrophysics Data System (ADS)

    Kowalczyk, P. J.; Puchalski, M.; Kozłowski, W.; Dąbrowski, P.; Klusek, Z.; Olejniczak, W.

    2008-05-01

    Scanning tunneling microscopy (STM) and spectroscopy (STS) carried out in vacuum and air were used to study the electronic structure of the Au (1 1 1) surface in the range of 0.0-0.7 eV below the Fermi level. The STS experiment carried out in UHV showed the existence of the Shockley surface state (SS) located 0.48 eV below the Fermi level. STS carried out in air showed strong local maximum located 0.35 eV below the Fermi level. This maximum was ascribed to the SS shifted toward lower energy due to carbon and oxygen overlayer. To confirm that the SS could exist on the sample exposed to air we did ultraviolet photoemission spectroscopy (UPS) experiment on air-treated and clean Au (1 1 1). Our results suggest that the SS position initially measured at 0.38 eV below the Fermi level was shifted to 0.27 eV after air treatment. Additionally, the level of contamination was measured using X-ray photoelectron spectroscopy (XPS).

  8. Full-solid-angle photoelectron diffraction from bulk and surface atoms of clean W(110)

    SciTech Connect

    Ynzunza, R. X.; Tober, E. D.; Palomares, F. J.; Wang, Z.; Daimon, H.; Chen, Y.; Hussain, Z.; Van Hove, M. A.; Fadley, C. S.

    1997-04-01

    The authors have studied the atomic structure of the clean W(110) surface by means of site-resolved scanned-angle W4f{sub 7/2} photoelectron diffraction (PD) data obtained over nearly the full 2{pi} solid angle above the surface. Prior to the availability of high-brightness sources such as the Advanced Light Source, such large high-resolution data sets were prohibitively time consuming to obtain. The well characterized W(110) system was used as a reference case to check the accuracy of structure determinations from such scanned-angle data via R-factor comparisons of experiment with theoretical multiple scattering calculations. The photoelectron kinetic energy of {approximately}40 eV used was also lower than in many prior PD studies, providing further challenges to theory. The influence of various non-structural theoretical input parameters (e.g., scattering phase shifts, electron inelastic attenuation length, and inner potential) was thus also assessed. A final optimized structure is presented, together with comments on the future applications of this method.

  9. EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Doppler backscattered-signal diagnostics of laser-induced surface hydrodynamic processes

    NASA Astrophysics Data System (ADS)

    Gordienko, Vyacheslav M.; Kurochkin, Nikolay N.; Markov, V. N.; Panchenko, Vladislav Ya; Pogosov, G. A.; Chastukhin, E. M.

    1995-02-01

    A method is proposed for on-line monitoring of laser industrial processing. The method is based on optical heterodyne measurements of the Doppler backscattering signal generated in the interaction zone. Qualitative and quantitative information on hydrodynamic flows in the interaction zone can be obtained. A report is given of measurements, carried out at cw CO2 laser radiation intensities up to 1 kW cm-2, on the surfaces of a number of condensed materials irradiated in the monostatic interaction configuration.

  10. Holmium:YAG laser in dentistry: photoconditioning of dentinal surfaces

    NASA Astrophysics Data System (ADS)

    Holt, Raleigh A.; Nordquist, Robert E.

    1994-09-01

    This in vitro study was undertaken to determine energy levels necessary to produce tubule closure and surface smoothing on dentinal surfaces of human teeth and their resultant temperature increases within the pulpal canals with the Holmium:YAG laser. An optimal working spot size and even absorption pattern were produced by defocusing the laser beam and evaluated by images produced on light exposed and developed photographic paper. The surface effects on dentin were examined by scanning electron microscopy. A thermocouple was positioned in the canals of fresh dissected dog jaws and attached to a recorder which produced a graph of the temperature changes. The in vitro research model for intrapulpal temperatures changes was verified by comparing premortem and postmortem temperature readings. The same protocol was used to evaluate temperature changes in fresh human extracted teeth. In vivo histological studies were conducted to evaluate the effects of HO:YAG laser energy on pulpal tissues. The results of these studies indicate the HO:YAG laser at a wavelength of 2.12 microns can be safely and effectively used for photoconditioning of the dentinal surfaces of teeth in clinical conditions.

  11. Surface-enhanced Raman scattering activity of niobium surface after irradiation with femtosecond laser pulses

    SciTech Connect

    Ivanov, Victor G.; Vlakhov, Emil S.; Stan, George E.; Socol, Marcela; Zamfirescu, Marian; Albu, Catalina; Mihailescu, Natalia; Negut, Irina; Luculescu, Catalin; Ristoscu, Carmen; Mihailescu, Ion N.

    2015-11-28

    The chemical modification of the niobium (Nb) surface after irradiation with femtosecond laser pulses was investigated by scanning electron microscopy coupled with energy dispersive spectroscopy, atomic force microscopy, grazing incidence X-ray diffraction, and micro-Raman spectroscopy. The physical-chemical analyses indicated that the laser treatment results in oxidation of the Nb surface, as well as in the formation of Nb hydrides. Remarkably, after the samples' washing in ethanol, a strong Surface-Enhanced Raman Scattering (SERS) signal originating from the toluene residual traces was evidenced. Further, it was observed that the laser irradiated Nb surface is able to provide a SERS enhancement of ∼1.3 × 10{sup 3} times for rhodamine 6G solutions. Thus, for the first time it was shown that Nb/Nb oxide surfaces could exhibit SERS functionality, and so one can expect applications in biological/biochemical screening or for sensing of dangerous environmental substances.

  12. Surface-enhanced Raman scattering activity of niobium surface after irradiation with femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Ivanov, Victor G.; Vlakhov, Emil S.; Stan, George E.; Zamfirescu, Marian; Albu, Catalina; Mihailescu, Natalia; Negut, Irina; Luculescu, Catalin; Socol, Marcela; Ristoscu, Carmen; Mihailescu, Ion N.

    2015-11-01

    The chemical modification of the niobium (Nb) surface after irradiation with femtosecond laser pulses was investigated by scanning electron microscopy coupled with energy dispersive spectroscopy, atomic force microscopy, grazing incidence X-ray diffraction, and micro-Raman spectroscopy. The physical-chemical analyses indicated that the laser treatment results in oxidation of the Nb surface, as well as in the formation of Nb hydrides. Remarkably, after the samples' washing in ethanol, a strong Surface-Enhanced Raman Scattering (SERS) signal originating from the toluene residual traces was evidenced. Further, it was observed that the laser irradiated Nb surface is able to provide a SERS enhancement of ˜1.3 × 103 times for rhodamine 6G solutions. Thus, for the first time it was shown that Nb/Nb oxide surfaces could exhibit SERS functionality, and so one can expect applications in biological/biochemical screening or for sensing of dangerous environmental substances.

  13. Computational study of a self-cleaning process on superhydrophobic surface

    NASA Astrophysics Data System (ADS)

    Farokhirad, Samaneh

    All substances around us are bounded by interfaces. In general, interface between different phases of materials are categorized as fluid-fluid, solid-fluid, and solid-solid. Fluid-fluid interfaces exhibit a distinct behavior by adapting their shape in response to external stimulus. For example, a liquid droplet on a substrate can undergo different wetting morphologies depending on topography and chemical composition of the surface. Fundamentally, interfacial phenomena arise at the limit between two immiscible phases, namely interface. The interface dynamic governs, to a great extent, physical processes such as impact and spreading of two immiscible media, and stabilization of foams and emulsions from break-up and coalescence. One of the recent challenging problems in the interface-driven fluid dynamics is the self-propulsion mechanism of droplets by means of different types of external forces such as electrical potential, or thermal Marangoni effect. Rapid removal of self-propelled droplet from the surface is an essential factor in terms of expense and efficiency for many applications including self-cleaning and enhanced heat and mass transfer to save energy and natural resources. A recent study on superhydrophobic nature of micro- and nanostructures of cicada wings offers a unique way for the self-propulsion process with no external force, namely coalescence-induced self-propelled jumping of droplet which can act effectively at any orientation. The biological importance of this new mechanism is associated with protecting such surfaces from long term exposure to colloidal particles such as microbial colloids and virus particles. Different interfacial phenomena can occur after out-of-plane jumping of droplet. If the departed droplet is landed back by gravity, it may impact and spread on the surface or coalesce with another droplet and again self-peopled itself to jump away from the surface. The complete removal of the propelled droplet to a sufficient distance

  14. Laser bioengineering of glass-titanium implants surface

    NASA Astrophysics Data System (ADS)

    Lusquiños, F.; Arias-González, F.; Penide, J.; del Val, J.; Comesaña, R.; Quintero, F.; Riveiro, A.; Boutinguiza, M.; Pascual, M. J.; Durán, A.; Pou, J.

    2013-11-01

    Osseointegration is the mean challenge when surgical treatments fight against load-bearing bone diseases. Absolute bone replacement by a synthetic implant has to be completed not only from the mechanics point of view, but also from a biological approach. Suitable strength, resilience and stress distribution of titanium alloy implants are spoiled by the lack of optimal biological characteristics. The inert quality of extra low interstitial titanium alloy, which make it the most attractive metallic alloy for biomedical applications, oppose to an ideal surface with bone cell affinity, and capable to stimulate bone attachment bone growth. Diverse laser treatments have been proven as effective tools to modify surface properties, such as wettability in contact to physiological fluids, or osteoblast guided and slightly enhanced attachment. The laser surface cladding can go beyond by providing titanium alloy surfaces with osteoconduction and osteoinduction properties. In this research work, the laser radiation is used to produce bioactive glass coatings on Ti6Al4V alloy substrates. Specific silicate bioactive glass compositions has been investigated to achieve suitable surface tension and viscosity temperature behavior during processing, and to provide with the required release of bone growth gene up regulation agents in the course of resorption mediated by physiological fluids. The produced coatings and interfaces, the surface osteoconduction properties, and the chemical species release in simulated physiological fluid were characterized by scanning electron microscopy (SEM), hot stage microscopy (HSM), X-ray diffraction (XRD), X ray fluorescence (XRF), and Fourier transform infrared spectroscopy (FTIR).

  15. Low-reflectance laser-induced surface nanostructures created with a picosecond laser

    NASA Astrophysics Data System (ADS)

    Sarbada, Shashank; Huang, Zhifeng; Shin, Yung C.; Ruan, Xiulin

    2016-04-01

    Using high-speed picosecond laser pulse irradiation, low-reflectance laser-induced periodic surface structures (LIPSS) have been created on polycrystalline silicon. The effects of laser fluence, scan speed, overlapping ratio and polarization angle on the formation of LIPSS are reported. The anti-reflective properties of periodic structures are discussed, and the ideal LIPSS for low surface reflectance is presented. A decrease of 35.7 % in average reflectance of the silicon wafer was achieved over the wavelength range of 400-860 nm when it was textured with LIPSS at high scan speeds of 4000 mm/s. Experimental results of broadband reflectance of silicon wafers textured with LIPSS have been compared with finite difference time domain simulations and are in good agreement, showing high predictability in reflectance values for different structures. The effects of changing the LIPSS profile, fill factor and valley depth on the surface reflectance were also analyzed through simulations.

  16. Applications of lasers to the solution of environmental problems

    SciTech Connect

    Allen, L.; Pang, H.-M.; Edelson, M.C.

    1995-12-31

    This presentation will focus on current work in the Ames Laboratory where laser ablation is being used for both analytical sampling and metal surface cleaning. Examples will be presented demonstrating the utility of optical spectroscopy for monitoring laser ablation processes.

  17. Means for phase locking the outputs of a surface emitting laser diode array

    NASA Technical Reports Server (NTRS)

    Lesh, James R. (Inventor)

    1987-01-01

    An array of diode lasers, either a two-dimensional array of surface emitting lasers, or a linear array of stripe lasers, is phase locked by a diode laser through a hologram which focuses the output of the diode laser into a set of distinct, spatially separated beams, each one focused onto the back facet of a separate diode laser of the array. The outputs of the diode lasers thus form an emitted coherent beam out of the front of the array.

  18. Energy-scalable temporal cleaning device for femtosecond laser pulses based on cross-polarized wave generation

    NASA Astrophysics Data System (ADS)

    Ricci, Aurélien; Jullien, Aurélie; Rousseau, Jean-Philippe; Liu, Yi; Houard, Aurélien; Ramirez, Patricia; Papadopoulos, Dimitris; Pellegrina, Alain; Georges, Patrick; Druon, Frédéric; Forget, Nicolas; Lopez-Martens, Rodrigo

    2013-04-01

    We report on a compact energy-scalable device for generating high-fidelity femtosecond laser pulses based on spatial filtering through a hollow-core fiber followed by a nonlinear crystal for cross-polarized wave (XPW) generation. This versatile device is suited for temporal pulse cleaning over a wide range of input energies (from 0.1 to >10 mJ) and is successfully qualified on different ultrafast laser systems. Full characterization of the XPW output is presented. In particular, we demonstrate the generation of 1.6 mJ energy pulses starting from 11 mJ input pulse energy. The temporal contrast of the pulses is enhanced by more than 4 orders of magnitude. In addition, pulse shortening from 40 fs down to 15 fs Fourier-transform limit yields an overall peak-power transmission of up to 50%. This device not only serves as an integrated pulse contrast filter inside an ultrafast laser amplifier but also as a simple back-end solution for temporal post-compression of amplified pulses.

  19. Energy-scalable temporal cleaning device for femtosecond laser pulses based on cross-polarized wave generation.

    PubMed

    Ricci, Aurélien; Jullien, Aurélie; Rousseau, Jean-Philippe; Liu, Yi; Houard, Aurélien; Ramirez, Patricia; Papadopoulos, Dimitris; Pellegrina, Alain; Georges, Patrick; Druon, Frédéric; Forget, Nicolas; Lopez-Martens, Rodrigo

    2013-04-01

    We report on a compact energy-scalable device for generating high-fidelity femtosecond laser pulses based on spatial filtering through a hollow-core fiber followed by a nonlinear crystal for cross-polarized wave (XPW) generation. This versatile device is suited for temporal pulse cleaning over a wide range of input energies (from 0.1 to >10 mJ) and is successfully qualified on different ultrafast laser systems. Full characterization of the XPW output is presented. In particular, we demonstrate the generation of 1.6 mJ energy pulses starting from 11 mJ input pulse energy. The temporal contrast of the pulses is enhanced by more than 4 orders of magnitude. In addition, pulse shortening from 40 fs down to 15 fs Fourier-transform limit yields an overall peak-power transmission of up to 50%. This device not only serves as an integrated pulse contrast filter inside an ultrafast laser amplifier but also as a simple back-end solution for temporal post-compression of amplified pulses.

  20. Nanorod Surface Plasmon Enhancement of Laser-Induced Ultrafast Demagnetization.

    PubMed

    Xu, Haitian; Hajisalem, Ghazal; Steeves, Geoffrey M; Gordon, Reuven; Choi, Byoung C

    2015-01-01

    Ultrafast laser-induced magnetization dynamics in ferromagnetic thin films were measured using a femtosecond Ti:sapphire laser in a pump-probe magneto-optic Kerr effect setup. The effect of plasmon resonance on the transient magnetization was investigated by drop-coating the ferromagnetic films with dimensionally-tuned gold nanorods supporting longitudinal surface plasmon resonance near the central wavelength of the pump laser. With ~4% nanorod areal coverage, we observe a >50% increase in demagnetization signal in nanorod-coated samples at pump fluences on the order of 0.1 mJ/cm(2) due to surface plasmon-mediated localized electric-field enhancement, an effect which becomes more significant at higher laser fluences. We were able to qualitatively reproduce the experimental observations using finite-difference time-domain simulations and mean-field theory. This dramatic enhancement of ultrafast laser-induced demagnetization points to possible applications of nanorod-coated thin films in heat-assisted magnetic recording. PMID:26515296

  1. Nanorod Surface Plasmon Enhancement of Laser-Induced Ultrafast Demagnetization

    PubMed Central

    Xu, Haitian; Hajisalem, Ghazal; Steeves, Geoffrey M.; Gordon, Reuven; Choi, Byoung C.

    2015-01-01

    Ultrafast laser-induced magnetization dynamics in ferromagnetic thin films were measured using a femtosecond Ti:sapphire laser in a pump-probe magneto-optic Kerr effect setup. The effect of plasmon resonance on the transient magnetization was investigated by drop-coating the ferromagnetic films with dimensionally-tuned gold nanorods supporting longitudinal surface plasmon resonance near the central wavelength of the pump laser. With ~4% nanorod areal coverage, we observe a >50% increase in demagnetization signal in nanorod-coated samples at pump fluences on the order of 0.1 mJ/cm2 due to surface plasmon-mediated localized electric-field enhancement, an effect which becomes more significant at higher laser fluences. We were able to qualitatively reproduce the experimental observations using finite-difference time-domain simulations and mean-field theory. This dramatic enhancement of ultrafast laser-induced demagnetization points to possible applications of nanorod-coated thin films in heat-assisted magnetic recording. PMID:26515296

  2. Femtosecond laser-induced periodic surface structures on silica

    SciTech Connect

    Hoehm, S.; Rosenfeld, A.; Krueger, J.; Bonse, J.

    2012-07-01

    The formation of laser-induced periodic surface structures (LIPSS) on two different silica polymorphs (single-crystalline synthetic quartz and commercial fused silica glass) upon irradiation in air with multiple linearly polarized single- and double-fs-laser pulse sequences ({tau} = 150 fs pulse duration, {lambda} = 800 nm center wavelength, temporal pulse separation {Delta}t < 40 ps) is studied experimentally and theoretically. Two distinct types of fs-LIPSS [so-called low-spatial-frequency LIPSS (LSFL) and high-spatial-frequency LIPSS (HSFL)] with different spatial periods and orientations were identified. Their appearance was characterized with respect to the experimental parameters peak laser fluence and number of laser pulses per spot. Additionally, the 'dynamics' of the LIPSS formation was addressed in complementary double-fs-pulse experiments with varying delays, revealing a characteristic change of the LSFL periods. The experimental results are interpreted on the basis of a Sipe-Drude model considering the carrier dependence of the optical properties of fs-laser excited silica. This new approach provides an explanation of the LSFL orientation parallel to the laser beam polarisation in silica - as opposed to the behaviour of most other materials.

  3. Tapered cavity surface emitting distributed Bragg reflector lasers

    NASA Astrophysics Data System (ADS)

    Luo, Hui

    2000-09-01

    High power, diffraction-limited semiconductor lasers are required for a wide range of applications such as pumping for EDFAs, Raman amplifiers, and for free space optical communications. Unstable resonator has been identified as a very promising concept to develop these lasers. The objective of this research is to investigate and develop tapered cavity unstable resonator grating coupled surface emitting lasers (TCSELs). The laser consists of a ridge section, a tapered gain section and a DBR grating section. The ridge is used to ensure single lateral mode operation. The taper is used to achieve high power from a large aperture. The grating is used to provide feedback and surface outcoupling. This laser design has several key features including high output power, near diffraction-limited beam, low divergence angle, single longitudinal mode operation, and integration with dynamic functionality such as wavelength tuning and beam steering. In this dissertation the design, fabrication and characterization of TCSELs are discussed. The theory of TCSELs is presented. As a theoretical investigation, a comprehensive numerical modeling based on finite difference beam propagation method (FD-BPM) for semiconductor laser is developed. The model includes major parameters affecting device performance such as current spreading, carrier diffusion, nonlinear gain- carrier relation, gain saturation, carrier induced antiguiding and thermal lensing. The simulation results are presented and effects of design parameters on device performance are discussed. TCSELs with different device design and functionality are fabricated. The characterization results are discussed. High power operation is obtained under both pulsed and continuous wave (CW) operation. Collimated near diffraction-limited beam is demonstrated with moderate power. Single longitudinal mode operation with high side mode suppression ratio is observed. Wavelength tuning and beam steering is achieved using current injection to

  4. Microscopical and chemical surface characterization of CAD/CAM zircona abutments after different cleaning procedures. A qualitative analysis

    PubMed Central

    2015-01-01

    PURPOSE To describe and characterize the surface topography and cleanliness of CAD/CAM manufactured zirconia abutments after steaming and ultrasonic cleaning. MATERIALS AND METHODS A total of 12 ceramic CAD/CAM implant abutments of various manufacturers were produced and randomly divided into two groups of six samples each (control and test group). Four two-piece hybrid abutments and two one-piece abutments made of zirconium-dioxide were assessed per each group. In the control group, cleaning by steam was performed. The test group underwent an ultrasonic cleaning procedure with acetone, ethyl alcohol and antibacterial solution. Groups were subjected to scanning electron microscope (SEM) analysis and Energy-dispersive X-ray spectroscopy (EDX) to verify and characterize contaminant chemical characterization non-quantitatively. RESULTS All zirconia CAD/CAM abutments in the present study displayed production-induced wear particles, debris as well as organic and inorganic contaminants. The abutments of the test group showed reduction of surface contamination after undergoing an ultrasonic cleaning procedure. However, an absolute removal of pollutants could not be achieved. CONCLUSION The presence of debris on the transmucosal surface of CAD/CAM zirconia abutments of various manufacturers was confirmed. Within the limits of the study design, the results suggest that a defined ultrasonic cleaning process can be advantageously employed to reduce such debris, thus, supposedly enhancing soft tissue healing. Although the adverse long-term influence of abutment contamination on the biological stability of peri-implant tissues has been evidenced, a standardized and validated polishing and cleaning protocol still has to be implemented. PMID:25932314

  5. Noncontact NDE of microscopic surface-breaking cracks using laser generated and detected ultrasonic surface waves

    NASA Astrophysics Data System (ADS)

    Cooney, Adam; Blackshire, James L.

    2004-07-01

    Laser ultrasonic imaging of surface acoustic waves on a material surface provides a non-contact and sensitive method for detecting and characterizing defects and anomalies in aerospace and industrial materials. It has recently been shown that the surface acoustic wave interactions with sharp material discontinuities such as surface-breaking cracks provides an additional benefit of an intensification of the displacement field in the immediate vicinity of the crack site. This near-field intensification can be exploited by scanning, point-by-point, a laser-ultrasonic system to create detailed microscopic images of the surface breaking cracks. In this effort, a number of laser ultrasonic system parameters were studied to better understand the optimized conditions to imaging surface breaking cracks using ultrasonic generation in the thermoelastic regime, and laser detection of ultrasound fields using heterodyne interferometer. In particular, laser beam sizes, separation distances, and motives were varied. In addition, several different time-gating analysis methods were studied, which had a significant effect on both the characteristics as well as the quality of the resultant crack images.

  6. Graphene surface emitting terahertz laser: Diffusion pumping concept

    SciTech Connect

    Davoyan, Arthur R.; Morozov, Mikhail Yu.; Popov, Vyacheslav V.; Satou, Akira; Otsuji, Taiichi

    2013-12-16

    We suggest a concept of a tunable graphene-based terahertz (THz) surface emitting laser with diffusion pumping. We employ significant difference in the electronic energy gap of graphene and a typical wide-gap semiconductor, and demonstrate that carriers generated in the semiconductor can be efficiently captured by graphene resulting in population inversion and corresponding THz lasing from graphene. We develop design principles for such a laser and estimate its performance. We predict up to 50 W/cm{sup 2} terahertz power output for 100 kW/cm{sup 2} pump power at frequency around 10 THz at room temperature.

  7. Direct laser fabrication of nanowires on semiconductor surfaces

    NASA Astrophysics Data System (ADS)

    Haghizadeh, Anahita; Yang, Haeyeon

    2016-03-01

    Periodic nanowires are observed from (001) orientation of Si and GaAs when the surfaces are irradiated interferentially by high power laser pulses. These nanowires are self-assembled and can be strain-free while their period is consistent with interference period. The nanowire morphologies are studied by atomic force microscopy. The observed period between nanowires depends on the wavelengths used and interference angle. The nanowire width increases with laser intensity. The narrowest nanowires observed have the width smaller than 20 nm, which is more than 10 times smaller than the interference period.

  8. Waterproof active paper via laser surface micropatterning of magnetic nanoparticles.

    PubMed

    Chitnis, G; Ziaie, B

    2012-09-26

    Paper is one of the oldest and most abundant materials known to man. Recently, there has been a considerable interest in creating paper devices by combining paper with other functional materials. In this letter, we demonstrate a simple fabrication technique to create water-resistant ferro-patterns on wax paper using CO(2) laser ablation. A resolution of about 100 μm is achieved which is mostly limited by the cellulose fiber size (~50 μm) in the wax paper and can be improved by using a smaller cellulose matrix. Laser ablation results in modification of surface morphology and chemistry, leading to a change in surface energy. We also present a 2D model for ferrofluid deposition relating the size of the pattern to the amount of ferroparticles deposited on the surface. Finally, a paper gripper is presented to demonstrate advantages of our technique, which allows microscale patterning and machining in a single step. PMID:22939525

  9. Mechanically durable superoleophobic aluminum surfaces with microstep and nanoreticula hierarchical structure for self-cleaning and anti-smudge properties.

    PubMed

    Peng, Shan; Bhushan, Bharat

    2016-01-01

    Superoleophobic aluminum surfaces are of interest for self-cleaning, anti-smudge (fingerprint resistance), anti-fouling, and corrosion resistance applications. In the published literature on superoleophobic aluminum surfaces, mechanical durability, self-cleaning, and anti-smudge properties data are lacking. Microstep structure has often been used to prepare superhydrophobic aluminum surfaces which produce the microstructure. The nanoreticula structure has also been used, and is reported to be able to trap air-pockets, which are desirable for a high contact angle. In this work, the microstep and nanoreticula structures were produced on aluminum surfaces to form a hierarchical micro/nanostructure by a simple two-step chemical etching process. The hierarchical structure, when modified with fluorosilane, made the surface superoleophobic. The effect of nanostructure, microstructure, and hierarchical structure on wettability and durability were studied and compared. The superoleophobic aluminum surfaces were found to be wear resistant, self-cleaning, and have anti-smudge and corrosion resistance properties. PMID:26407055

  10. Formation of highly corrosion resistant stainless steel surface alloys for marine environments by laser surface alloying

    SciTech Connect

    Sridhar, K.; Deshmukh, M.B.; Khanna, A.S.; Wissenbach, K.

    1998-12-31

    Austenitic stainless steels (SS) such as UNS S30403 are being used for numerous industrial applications due to their goad mechanical properties and weldability. However in aggressive marine environments such as seawater, they suffer from localized corrosion. Even though newly developed highly alloyed SS`s possess very high pitting resistance, they are susceptible to the formation of secondary phases. In the present study, a laser surface alloying technique was employed for the formation of highly alloyed austenitic stainless steel surfaces on conventional 304 SS substrate. Microstructural characterization by optical and SEM revealed finer cells of austenitic phase in the laser alloyed zones with molybdenum contents in the range of 3 to 15 wt%. The pitting corrosion resistance of the surface alloys were ascertained by immersion and potentiodynamic polarization tests and the repassivation behavior by cyclic polarization tests. Also the influence of microstructural features on pitting behavior of highly alloyed and laser surface alloyed steels is studied.

  11. Investigation of UV Laser Triggered, Nanosecond, Surface Flashover Switches

    SciTech Connect

    Nunnally, W C; Neurath, R; Holmes, C; Sampayan, S; Caporaso, G

    2003-06-03

    Triggered, multi-channel, surface discharges or surface flashover switching have been investigated as a low inductance, low pulse rate switch for conducting large currents. This paper discusses the investigation of UV (355 nm) laser triggered, single channel, low inductance, ns closure and sub-ns jitter switches for applications in switching high dielectric constant, compact pulse forming lines into accelerator loads. The experimental arrangement for evaluating the switch performance and for measuring the high field dielectric constant of the pulse forming lines is presented. Experimental results of delay and jitter measurements versus optical energy on the flashover surface and dc electric field charge.

  12. Quantization of surface rust by using laser imaging techniques

    NASA Astrophysics Data System (ADS)

    Koyuncu, B.; Yasin, A.; Abu-Rezq, A.

    1995-06-01

    Laser speckle interferometry 1,2 and image processing 3,4 have been used to detect and quantize the rust build-up on metal surfaces under water. Speckle information from the sample metal surface was captured by a CCD camera and a frame grabber card. Software techniques were used to convert the image data files into ASCII files in an appropriate format. Three-dimensional surface plots were generated to define the numerical values for the amout of rust build-up.

  13. Formation of laser-induced periodic surface structures on niobium by femtosecond laser irradiation

    SciTech Connect

    Pan, A.; Dias, A.; Gomez-Aranzadi, M.; Olaizola, S. M.; Rodriguez, A.

    2014-05-07

    The surface morphology of a Niobium sample, irradiated in air by a femtosecond laser with a wavelength of 800 nm and pulse duration of 100 fs, was examined. The period of the micro/nanostructures, parallel and perpendicularly oriented to the linearly polarized fs-laser beam, was studied by means of 2D Fast Fourier Transform analysis. The observed Laser-Induced Periodic Surface Structures (LIPSS) were classified as Low Spatial Frequency LIPSS (periods about 600 nm) and High Spatial Frequency LIPSS, showing a periodicity around 300 nm, both of them perpendicularly oriented to the polarization of the incident laser wave. Moreover, parallel high spatial frequency LIPSS were observed with periods around 100 nm located at the peripheral areas of the laser fingerprint and overwritten on the perpendicular periodic gratings. The results indicate that this method of micro/nanostructuring allows controlling the Niobium grating period by the number of pulses applied, so the scan speed and not the fluence is the key parameter of control. A discussion on the mechanism of the surface topology evolution was also introduced.

  14. Structurally colored surfaces with antireflective, self-cleaning, and antifogging properties.

    PubMed

    Du, Xin; He, Junhui

    2012-09-01

    This article describes a simple method to fabricate uniform porous antireflective (AR) coatings composed of nanoflakes on the surface of soda lime glass through one-step hydrothermal alkali (NaOH) etching process. Experimental conditions including reaction temperature, NaOH concentration, and reaction time were investigated to find the optimal etching conditions, and the maximum transmittance increases from 90.5% to 98.5%. The coating thickness increases with increase in the NaOH concentration, leading to the tunable red-shift of transmission and reflection spectra in the UV and entire visible range. And the corresponding uniform structural reflected colors varying from gray, pale yellow, yellow, pink, blue to pale blue are observed when the etched glasses are viewed in reflected light. The relationship of coating thickness, transmittance, reflectance, and reflected color was obtained and discussed. The etched glass after introducing TiO(2) component onto the porous coating had AR, self-cleaning (superhydrophilic and photocatalytic) and antifogging properties. It is conceivable that such etched glasses would have broad potential applications in optical devices, solar cells, light emitting diodes, and varied window glasses.

  15. Rapid laser surface enamelling by powder feeding technique

    NASA Astrophysics Data System (ADS)

    Akhter, R.; Li, L.; Edwards, R. E.; Gale, A. W.

    2003-03-01

    Enamelling processes normally require very long curing/setting time typically 30-60 min. This paper reports a new rapid laser enamelling process by powder feeding technique with curing time less than 2 s. A special application of the technique has been developed for tile grout sealing. The laser parameters and their effects on the enamelling process are presented. It has been found that a good smooth enamel surface free of porosities can be produced by powder feeding technique. The increase in scan speed reduces the width of the seal, while an increase in laser power increases the width of the seal. The interface characteristics between the enamel and the substrate are investigated.

  16. Self-organizing microstructures orientation control in femtosecond laser patterning on silicon surface.

    PubMed

    Liu, Pengjun; Jiang, Lan; Hu, Jie; Zhang, Shuai; Lu, Yongfeng

    2014-07-14

    Self-organizing rippled microstructures are induced on silicon surface by linearly polarized femtosecond laser pulses. At a near threshold fluence, it is observed that ripple orientation is co-determined by the laser polarization direction and laser scanning parameters (scanning direction and scanning speed) in surface patterning process. Under fixed laser polarization, the ripple orientation can be controlled to rotate by about 40° through changing laser scanning parameters. In addition, it is also observed that the ripple morphology is sensitive to the laser scanning direction, and it is an optimal choice to obtain ordered ripple structures when the angle between laser scanning and laser polarization is less than 45°.

  17. ATP Bioluminometers Analysis on the Surfaces of Removable Orthodontic Aligners after the Use of Different Cleaning Methods.

    PubMed

    Levrini, Luca; Mangano, Alessandro; Margherini, Silvia; Tenconi, Camilla; Vigetti, Davide; Muollo, Raffaele; Marco Abbate, Gian

    2016-01-01

    Purpose. The aim was to quantify the bacteria concentration on the surface of orthodontic clear aligners using three different cleaning methods. Furthermore the objective was to validate the efficacy of the bioluminometer in assessing the bacteria concentration. Materials and Methods. Twenty subjects (six males and fourteen females) undergoing orthodontic therapy with clear aligners (Invisalign® Align Technology, Santa Clara, California) were enrolled in this study. The observation time was of six weeks. The patients were instructed to use different cleaning methods (water, brushing with toothpaste, and brushing with toothpaste and use of sodium carbonate and sulphate tablet). At the end of each phase a microbiological analysis was performed using the bioluminometer. Results. The highest bacteria concentration was found on aligners cleaned using only water (583 relative light units); a value of 189 relative light units was found on aligners cleaned with brushing and toothpaste. The lowest bacteria concentration was recorded on aligners cleaned with brushing and toothpaste and the use of sodium carbonate and sulfate tablet. Conclusions. The mechanical removal of the bacterial biofilm proved to be effective with brushing and toothpaste. The best results in terms of bacteria concentration were achieved adding the use of sodium carbonate and sulfate tablet.

  18. ATP Bioluminometers Analysis on the Surfaces of Removable Orthodontic Aligners after the Use of Different Cleaning Methods

    PubMed Central

    Levrini, Luca; Mangano, Alessandro; Margherini, Silvia; Tenconi, Camilla; Vigetti, Davide; Muollo, Raffaele; Marco Abbate, Gian

    2016-01-01

    Purpose. The aim was to quantify the bacteria concentration on the surface of orthodontic clear aligners using three different cleaning methods. Furthermore the objective was to validate the efficacy of the bioluminometer in assessing the bacteria concentration. Materials and Methods. Twenty subjects (six males and fourteen females) undergoing orthodontic therapy with clear aligners (Invisalign® Align Technology, Santa Clara, California) were enrolled in this study. The observation time was of six weeks. The patients were instructed to use different cleaning methods (water, brushing with toothpaste, and brushing with toothpaste and use of sodium carbonate and sulphate tablet). At the end of each phase a microbiological analysis was performed using the bioluminometer. Results. The highest bacteria concentration was found on aligners cleaned using only water (583 relative light units); a value of 189 relative light units was found on aligners cleaned with brushing and toothpaste. The lowest bacteria concentration was recorded on aligners cleaned with brushing and toothpaste and the use of sodium carbonate and sulfate tablet. Conclusions. The mechanical removal of the bacterial biofilm proved to be effective with brushing and toothpaste. The best results in terms of bacteria concentration were achieved adding the use of sodium carbonate and sulfate tablet. PMID:27242901

  19. Diagnosis of materials and effectiveness of Er:YAG laser cleaning as complementary treatment in a panel painting attributed to Lluís Borrassà (fifteenth century)

    NASA Astrophysics Data System (ADS)

    Andreotti, Alessia; Brown, William P.; Camaiti, Mara; Colombini, Maria Perla; DeCruz, Adele

    2016-06-01

    A fifteenth-century panel painting by Lluís Borrassà (1360-1425) was the object of a restoration at the North Carolina Museum of Art. A multi-analytical approach based on Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy and gas chromatography-mass spectrometry (GC/MS) also coupled with a pyrolyzer was used to investigate the origin of the darkened coating obscuring the work of art in order to find a proper cleaning procedure. The results evidenced the presence of different restoration materials that constituted the superficial patina, which was difficult to remove by conventional solvent cleaning methods. The Er:YAG laser operating at 2.94 μm was tested as an innovative alternative method to the traditional solvent mixture and gels. Because of the presence of multilayers of over-painting and restoration materials, the Er:YAG laser also proved beneficial as a nondestructive and selective sampling tool. The organic material was collected by positioning a microscope glass coverslip (15 × 15 mm) on the painting surface, followed with laser ablation that removed the material, which condensed on the glass that was then submitted for the FTIR and GC-MS analyses. The acquired new knowledge of the characterized materials and optimization of the cleaning methods guided the conservators to choose the best restoration conditions and perform a safe and successful cleaning of the painting especially the blue pigment, which was covered with intractable restoration material. The Er:YAG was an efficient and safe method to remove these materials.

  20. LEED crystallography studies of the structure of clean and adsorbate-covered Ir, Pt and Rh crystal surfaces

    SciTech Connect

    Koestner, R.J.

    1982-08-01

    There have only been a few Low Energy Electron Diffraction (LEED) intensity analyses carried out to determine the structure of molecules adsorbed on metal surfaces; most surface crystallography studies concentrated on the structure of clean unreconstructed or atomic adsorbate-covered transition metal faces. The few molecular adsorption systems already investigated by dynamical LEED are CO on Ni(100), Cu(100) and Pd(100) as well as C/sub 2/H/sub 2/ and C/sub 2/H/sub 4/ adsorbed on Pt(111). The emphasis of this thesis research has been to extend the applicability of LEED crystallography to the more complicated unit cells found in molecular overlayers on transition metals or in there constructed surfaces of clean transition metals.

  1. Ultrahigh vacuum and low-temperature cleaning of oxide surfaces using a low-concentration ozone beam

    SciTech Connect

    Pratt, A.; Graziosi, P.; Bergenti, I.; Dediu, A.; Prezioso, M.; Yamauchi, Y.

    2014-07-15

    We present a novel method of delivering a low-concentration (<15%) ozone beam to an ultra-high vacuum environment for the purpose of cleaning and dosing experimental samples through oxidation processing. The system described is safe, low-cost, and practical and overcomes the limitations of ozone transport in the molecular flow environment of high or ultrahigh vacuum whilst circumventing the use of pure ozone gas which is potentially highly explosive. The effectiveness of this method in removing surface contamination is demonstrated through comparison of high-temperature annealing of a simple oxide (MgO) in ozone and oxygen environments as monitored using quadrupole mass spectroscopy and Auger electron spectroscopy. Additionally, we demonstrate the potential of ozone for obtaining clean complex oxide surfaces without the need for high-temperature annealing which may significantly alter surface structure.

  2. Washable and wear-resistant superhydrophobic surfaces with self-cleaning property by chemical etching of fibers and hydrophobization.

    PubMed

    Xue, Chao-Hua; Li, Ya-Ru; Zhang, Ping; Ma, Jian-Zhong; Jia, Shun-Tian

    2014-07-01

    Superhydrophobic poly(ethylene terephthalate) (PET) textile surfaces with a self-cleaning property were fabricated by treating the microscale fibers with alkali followed by coating with polydimethylsiloxane (PDMS). Scanning electron microscopy analysis showed that alkali treatment etched the PET and resulted in nanoscale pits on the fiber surfaces, making the textiles have hierarchical structures. Coating of PDMS on the etched fibers affected little the roughening structures while lowered the surface energy of the fibers, thus making the textiles show slippery superhydrophobicity with a self-cleaning effect. Wettability tests showed that the superhydrophobic textiles were robust to acid/alkaline etching, UV irradiation, and long-time laundering. Importantly, the textiles maintained superhydrophobicity even when the textiles are ruptured by severe abrasion. Also colorful images could be imparted to the superhydrophobic textiles by a conventional transfer printing without affecting the superhydrophobicity.

  3. Aluminium surface treatment with ceramic phases using diode laser

    NASA Astrophysics Data System (ADS)

    Labisz, K.; Tański, T.; Brytan, Z.; Pakieła, W.; Wiśniowski, M.

    2016-07-01

    Ceramic particles powder feeding into surface layer of engineering metal alloy is a well-known and widely used technique. New approach into the topic is to obtain finely distributed nano-sized particles involved in the aluminium matrix using the traditional laser technology. In this paper are presented results of microstructure investigation of cast aluminium-silicon-copper alloys surface layer after heat treatment and alloying with ceramic carbides of WC and ZrO2 using high-power diode laser. The surface layer was specially prepared for the reason of reducing the reflectivity, which is the main problem in the up-to-date metal matrix composites production. With scanning electron microscopy, it was possible to determine the deformation process and distribution of WC and ZrO2 ceramic powder phase. Structure of the surface after laser treatment changes, revealing three zones—remelting zone, heat-affected zone and transition zone placed over the Al substrate. The structural changes of ceramic powder, its distribution and morphology as well as microstructure of the matrix material influence on functional properties, especially wear resistance and hardness of the achieved layer, were investigated.

  4. Particle generation by ultraviolet-laser ablation during surface decontamination.

    PubMed

    Lee, Doh-Won; Cheng, Meng-Dawn

    2006-11-01

    A novel photonic decontamination method was developed for removal of pollutants from material surfaces. Such a method relies on the ability of a high-energy laser beam to ablate materials from a contaminated surface layer, thus producing airborne particles. In this paper, the authors presented the results obtained using a scanning mobility particle sizer (SMPS) system and an aerosol particle sizer (APS). Particles generated by laser ablation from the surfaces of cement, chromium-embedded cement, and alumina were experimentally investigated. Broad particle distributions from nanometer to micrometer in size were measured. For stainless steel, virtually no particle > 500 nm in aerodynamic size was detected. The generated particle number concentrations of all three of the materials were increased as the 266-nm laser fluence (millijoules per square centimeter) increased. Among the three materials tested, cement was found to be the most favorable for particle removal, alumina next, and stainless steel the least. Chromium (dropped in cement) showed almost no effects on particle production. For all of the materials tested except for stainless steel, bimodal size distributions were observed; a smaller mode peaked at approximately 50-70 nm was detected by SMPS and a larger mode (peaked at approximately 0.70-0.85 microm) by APS. Based on transmission electron microscopy observations, the authors concluded that particles in the range of 50-70 nm were aggregates of primary particles, and those of size larger than a few hundred nanometers were produced by different mechanisms, for example, massive object ejection from the material surfaces.

  5. Femtosecond laser induced nanostructuring for surface enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Messaoudi, H.; Das, S. K.; Lange, J.; Heinrich, F.; Schrader, S.; Frohme, M.; Grunwald, R.

    2014-03-01

    The formation of periodical nanostructures with femtosecond laser pulses was used to create highly efficient substrates for surface-enhanced Raman spectroscopy (SERS). We report about the structuring of silver and copper substrates and their application to the SERS of DNA (herring sperm) and protein molecules (egg albumen). The maximum enhancement factors were found on Ag substrates processed with the second harmonic generation (SHG) of a 1-kHz Ti:sapphire laser and structure periods near the SHG wavelength. In the case of copper, however, the highest enhancement was obtained with long-period ripples induced with at fundamental wavelength. This is explained by an additional significant influence of nanoparticles on the surface. Nanostructured areas in the range of 1.25 mm2 were obtained in 10 s. The surfaces were characterized by scanning electron microscopy, Fast Fourier Transform and Raman spectroscopy. Moreover, the role of the chemical modification of the metal structures is addressed. Thin oxide layers resulting from working in atmosphere which improve the biocompatibility were indicated by vibration spectra. It is expected that the detailed study of the mechanisms of laser-induced nanostructure formation will stimulate further applications of functionalized surfaces like photocatalysis, selective chemistry and nano-biology.

  6. AFM CHARACTERIZATION OF RAMAN LASER INDUCED DAMAGE ON CDZNTECRYSTAL SURFACES

    SciTech Connect

    Teague, L.; Duff, M.

    2008-10-07

    High quality CdZnTe (or CZT) crystals have the potential for use in room temperature gamma-ray and X-ray spectrometers. Over the last decade, the methods for growing high quality CZT have improved the quality of the produced crystals however there are material features that can influence the performance of these materials as radiation detectors. The presence of structural heterogeneities within the crystals, such as twinning, pipes, grain boundaries (polycrystallinity), and secondary phases (SPs) can have an impact on the detector performance. There is considerable need for reliable and reproducible characterization methods for the measurement of crystal quality. With improvements in material characterization and synthesis, these crystals may become suitable for widespread use in gamma radiation detection. Characterization techniques currently utilized to test for quality and/or to predict performance of the crystal as a gamma-ray detector include infrared (IR) transmission imaging, synchrotron X-ray topography, photoluminescence spectroscopy, transmission electron microscopy (TEM), atomic force microscopy (AFM) and Raman spectroscopy. In some cases, damage caused by characterization methods can have deleterious effects on the crystal performance. The availability of non-destructive analysis techniques is essential to validate a crystal's quality and its ability to be used for either qualitative or quantitative gamma-ray or X-ray detection. The work presented herein discusses the damage that occurs during characterization of the CZT surface by a laser during Raman spectroscopy, even at minimal laser powers. Previous Raman studies have shown that the localized annealing from tightly focused, low powered lasers results in areas of higher Te concentration on the CZT surface. This type of laser damage on the surface resulted in decreased detector performance which was most likely due to increased leakage current caused by areas of higher Te concentration. In this study

  7. A versatile elevated-pressure reactor combined with an ultrahigh vacuum surface setup for efficient testing of model and powder catalysts under clean gas-phase conditions

    SciTech Connect

    Morfin, Franck; Piccolo, Laurent

    2013-09-15

    A small-volume reaction cell for catalytic or photocatalytic testing of solid materials at pressures up to 1000 Torr has been coupled to a surface-science setup used for standard sample preparation and characterization under ultrahigh vacuum (UHV). The reactor and sample holder designs allow easy sample transfer from/to the UHV chamber, and investigation of both planar and small amounts of powder catalysts under the same conditions. The sample is heated with an infrared laser beam and its temperature is measured with a compact pyrometer. Combined in a regulation loop, this system ensures fast and accurate temperature control as well as clean heating. The reaction products are automatically sampled and analyzed by mass spectrometry and/or gas chromatography (GC). Unlike previous systems, our GC apparatus does not use a recirculation loop and allows working in clean conditions at pressures as low as 1 Torr while detecting partial pressures smaller than 10{sup −4} Torr. The efficiency and versatility of the reactor are demonstrated in the study of two catalytic systems: butadiene hydrogenation on Pd(100) and CO oxidation over an AuRh/TiO{sub 2} powder catalyst.

  8. A versatile elevated-pressure reactor combined with an ultrahigh vacuum surface setup for efficient testing of model and powder catalysts under clean gas-phase conditions.

    PubMed

    Morfin, Franck; Piccolo, Laurent

    2013-09-01

    A small-volume reaction cell for catalytic or photocatalytic testing of solid materials at pressures up to 1000 Torr has been coupled to a surface-science setup used for standard sample preparation and characterization under ultrahigh vacuum (UHV). The reactor and sample holder designs allow easy sample transfer from/to the UHV chamber, and investigation of both planar and small amounts of powder catalysts under the same conditions. The sample is heated with an infrared laser beam and its temperature is measured with a compact pyrometer. Combined in a regulation loop, this system ensures fast and accurate temperature control as well as clean heating. The reaction products are automatically sampled and analyzed by mass spectrometry and/or gas chromatography (GC). Unlike previous systems, our GC apparatus does not use a recirculation loop and allows working in clean conditions at pressures as low as 1 Torr while detecting partial pressures smaller than 10(-4) Torr. The efficiency and versatility of the reactor are demonstrated in the study of two catalytic systems: butadiene hydrogenation on Pd(100) and CO oxidation over an AuRh/TiO2 powder catalyst. PMID:24089839

  9. Polishing slurry induced surface haze on phosphate laser glasses

    SciTech Connect

    Suratwala, T I; Miller, P E; Ehrmann, P R; Steele, R A

    2004-03-12

    The effects of residual polishing slurry on the surface topology of highly-polished, Nd-doped metaphosphate laser glasses are reported. Glass samples were pitched polished using cerium oxide or zirconium oxide slurry at different pHs and then washed by different methods that allowed varying amounts of residual slurry to ''dry'' on the surface. Upon re-washing with water, some of the samples showed surface haze (scatter), which scaled with the amount of residual slurry. Profilometry measurements showed that the haze is the result of shallow surface pits (100 nm - 20 {micro}m wide x {approx}15 nm deep). Chemical analyses of material removed during rewashing, confirmed the removal of glass components as well as the preferential removal of modifier ions (e.g. K{sup 1+} and Mg{sup 2+}). The surface pits appear to result from reaction of the glass with condensed liquid at the slurry particle-glass interface that produces water-soluble phosphate products that dissolves away with subsequent water contact. Aggressive washing, to remove residual slurry immediately following polishing, can minimize surface haze on phosphate glasses. It is desirable to eliminate haze from glass used in high-peak-power lasers, since it can cause scatter-induced optical modulation that can cause damage to downstream optics.

  10. X-ray photoemission analysis of clean and carbon monoxide-chemisorbed platinum(111) stepped surfaces using a curved crystal

    PubMed Central

    Walter, Andrew L.; Schiller, Frederik; Corso, Martina; Merte, Lindsay R.; Bertram, Florian; Lobo-Checa, Jorge; Shipilin, Mikhail; Gustafson, Johan; Lundgren, Edvin; Brión-Ríos, Anto´n X.; Cabrera-Sanfelix, Pepa; Sánchez-Portal, Daniel; Ortega, J. Enrique

    2015-01-01

    Surface chemistry and catalysis studies could significantly gain from the systematic variation of surface active sites, tested under the very same conditions. Curved crystals are excellent platforms to perform such systematics, which may in turn allow to better resolve fundamental properties and reveal new phenomena. This is demonstrated here for the carbon monoxide/platinum system. We curve a platinum crystal around the high-symmetry (111) direction and carry out photoemission scans on top. This renders the spatial core-level imaging of carbon monoxide adsorbed on a ‘tunable' vicinal surface, allowing a straightforward visualization of the rich chemisorption phenomenology at steps and terraces. Through such photoemission images we probe a characteristic elastic strain variation at stepped surfaces, and unveil subtle stress-release effects on clean and covered vicinal surfaces. These results offer the prospect of applying the curved surface approach to rationally investigate the chemical activity of surfaces under real pressure conditions. PMID:26561388

  11. X-ray photoemission analysis of clean and carbon monoxide-chemisorbed platinum(111) stepped surfaces using a curved crystal

    DOE PAGES

    Walter, Andrew L.; Schiller, Frederik; Corso, Martina; Merte, Lindsay R.; Bertram, Florian; Lobo-Checa, Jorge; Shipilin, Mikhail; Gustafson, Johan; Lundgren, Edvin; Brión-Ríos, Anto´n X.; et al

    2015-11-12

    Surface chemistry and catalysis studies could significantly gain from the systematic variation of surface active sites, tested under the very same conditions. Curved crystals are excellent platforms to perform such systematics, which may in turn allow to better resolve fundamental properties and reveal new phenomena. This is demonstrated here for the carbon monoxide/platinum system. We curve a platinum crystal around the high-symmetry (111) direction and carry out photoemission scans on top. This renders the spatial core-level imaging of carbon monoxide adsorbed on a 'tunable' vicinal surface, allowing a straightforward visualization of the rich chemisorption phenomenology at steps and terraces. Throughmore » such photoemission images we probe a characteristic elastic strain variation at stepped surfaces, and unveil subtle stress-release effects on clean and covered vicinal surfaces. Lastly, these results offer the prospect of applying the curved surface approach to rationally investigate the chemical activity of surfaces under real pressure conditions.« less

  12. X-ray photoemission analysis of clean and carbon monoxide-chemisorbed platinum(111) stepped surfaces using a curved crystal

    SciTech Connect

    Walter, Andrew L.; Schiller, Frederik; Merte, Lindsay R.; Bertram, Florian; Lobo-Checa, Jorge; Gustafson, Johan; Lundgren, Edvin; Brión-Ríos, Anto´n X.; Cabrera-Sanfelix, Pepa; Sánchez-Portal, Daniel

    2015-11-12

    Surface chemistry and catalysis studies could significantly gain from the systematic variation of surface active sites, tested under the very same conditions. Curved crystals are excellent platforms to perform such systematics, which may in turn allow to better resolve fundamental properties and reveal new phenomena. This is demonstrated here for the carbon monoxide/platinum system. We curve a platinum crystal around the high-symmetry (111) direction and carry out photoemission scans on top. This renders the spatial core-level imaging of carbon monoxide adsorbed on a 'tunable' vicinal surface, allowing a straightforward visualization of the rich chemisorption phenomenology at steps and terraces. Through such photoemission images we probe a characteristic elastic strain variation at stepped surfaces, and unveil subtle stress-release effects on clean and covered vicinal surfaces. Lastly, these results offer the prospect of applying the curved surface approach to rationally investigate the chemical activity of surfaces under real pressure conditions.

  13. Development of megasonic cleaning for silicon wafers

    NASA Technical Reports Server (NTRS)

    Mayer, A.

    1980-01-01

    A cleaning and drying system for processing at least 2500 three in. diameter wafers per hour was developed with a reduction in process cost. The system consists of an ammonia hydrogen peroxide bath in which both surfaces of 3/32 in. spaced, ion implanted wafers are cleaned in quartz carriers moved on a belt past two pairs of megasonic transducers. The wafers are dried in the novel room temperature, high velocity air dryer in the same carriers used for annealing. A new laser scanner was used effectively to monitor the cleaning ability on a sampling basis.

  14. Laser surface fusion of plasma sprayed ceramic turbine seals

    NASA Technical Reports Server (NTRS)

    Wisander, D. W.; Bill, R. C. (Inventor)

    1981-01-01

    The thermal shock resistance of a ceramic layer is improved. An improved abradable lining that is deposited on a shroud forming a gas path seal in turbomachinery is emphasized. Improved thermal shock resistance of a shroud is effective through the deliberate introduction of 'benign' cracks. These are microcracks which will not propagate appreciably upon exposure to the thermal shock environment in which a turbine seal must function. Laser surface fusion treatment is used to introduce these microcracks. The ceramic surface is laser scanned to form a continuous dense layer. As this cools and solidifies, shrinkage results in the formation of a very fine crack network. The presence of this deliberately introduced fine crack network precludes the formation of a catastrophic crack during thermal shock exposure.

  15. Porosity/bubble formation mechanism in laser surface enamelling

    NASA Astrophysics Data System (ADS)

    Akhter, R.; Li, L.; Edwards, R. E.; Gale, A. W.

    2003-03-01

    The grouts between commercial tiles applied to walls and floors can be contaminated over time and normally have to be removed by manual or mechanical processes. To overcome the contamination problem, a specially developed tile grout was used to fill the voids between the tiles. The base filler was overlaid with an enamel surface that glazes after laser irradiation. One problem discovered in this work is that bubbles and porosities were formed after laser treatment. The use of water glass (sodium silicate) as a binder has been undertaken in this study. This paper investigates the mechanism of bubble formation and its effects on the enamel surface. It has been found that the CO 2 gas released during the reaction causes bubble formation. The results and the technique for the removal of bubbles/porosities are presented in the paper.

  16. Vertical-cavity surface-emitting laser device

    DOEpatents

    Hadley, G.R.; Lear, K.L.; Awyoung, A.; Choquette, K.D.

    1999-05-11

    A vertical-cavity surface-emitting laser device is disclosed. The vertical-cavity surface-emitting laser (VCSEL) device comprises one or more VCSELs with each VCSEL having a mode-control region thereabout, with the mode-control region forming an optical cavity with an effective cavity length different from the effective cavity length within each VCSEL. Embodiments of the present invention can be formed as single VCSELs and as one- or two-dimensional arrays of VCSELs, with either an index-guided mode of operation or an index anti-guided mode of operation being defined by a sign of the difference in the two effective cavity lengths. 10 figs.

  17. Low Temperature Silicon Surface Cleaning by HF Etching/Ultraviolet Ozone Cleaning (HF/UVOC) Method (I)—Optimization of the HF Treatment—

    NASA Astrophysics Data System (ADS)

    Suemitsu, Maki; Kaneko, Tetsuya; Miyamoto, Nobuo

    1989-12-01

    Several variations of fluoric acid (HF) treatments of silicon substrates were examined for their adaptability as a pretreatment method for a silicon epitaxy process. Treatments with and without distilled, deionized (DI) water rinse, of different HF concentrations, and of different methods of HF supply were tested and their residual carbonic impurity contents were measured using RHEED. As a result, HF treatments by themselves were found to be insufficient in passivating the surface dangling bonds irrespective of the method of HF supply: dipping into the solution or exposure to the vapor. The optimum procedure of HF treatment thus proposed is a succession of (a) HF dipping, (b) DI-water rinsing, (c) nitrogen-gas blowing, and (d) UV-ozone cleaning.

  18. Laboratory evaluations of elmex inter X toothbrushes for interproximal access efficacy and posterior tooth surface cleaning.

    PubMed

    Yankell, S L; Shi, X; Emling, R C

    2002-01-01

    Laboratory methods have been developed to evaluate the ability of toothbrush bristles to remove artificial plaque deposits at interproximal sites (Interproximal Access Efficacy; IAE) and on distal tooth surfaces (Posterior Tooth Surface Cleaning; PTSC). In the testing performed for this study, six toothbrushes were evaluated. These were: elmex inter X Sensitive; elmex inter X Sensitive Short Head; elmex inter X medium; elmex inter X Medium Short Head; Oral-B Cross Action 40 medium; and the ADA reference standard toothbrush. Six toothbrushes of each design were tested four times under wet brushing conditions in all assays. In the IAE studies, toothbrushing was conducted using a vertical or horizontal brushing motion, simulated anterior or posterior teeth, and a brushing weight of 250 g. The bristles were placed at a 90 degree angle to the tooth surface, and brushing was performed for 15 seconds at two strokes per second with 50 mm strokes. IAE was recorded as the maximum width of simulated plaque deposit removed. For the PTSC evaluations, a horizontal brushing motion was used on posterior tooth shapes, with a 250 g brushing pressure for ten seconds. PTSC was determined as the maximum measurement of artificial plaque deposit removed from the mid-facial area to the maximum post-distal area of the most posterior simulated tooth shape. All data were assessed with ANOVA and the post hoc Tukey test. In the individual IAE tests, with vertical or horizontal brushing on anterior and posterior simulated teeth, and on overall IAE mean values, the four elmex inter X toothbrushes were significantly higher (p < 0.01-0.001) than the ADA reference standard and the Oral-B Cross Action 40 toothbrushes. The mean PTSC values for all toothbrushes were significantly higher (p < 0.01-0.001) compared to the ADA Reference Standard toothbrush mean PTSC. All elmex inter X brushes were statistically significantly higher (p < 0.01-0.001) compared to the Oral-B Cross Action 40 product. The elmex

  19. Tuning micropillar cavity birefringence by laser induced surface defects

    SciTech Connect

    Bonato, Cristian; Ding Dapeng; Gudat, Jan; Exter, Martin P. van; Thon, Susanna; Kim, Hyochul; Petroff, Pierre M.; Bouwmeester, Dirk

    2009-12-21

    We demonstrate a technique to tune the optical properties of micropillar cavities by creating small defects on the sample surface near the cavity region with an intense focused laser beam. Such defects modify strain in the structure, changing the birefringence in a controllable way. We apply the technique to make the fundamental cavity mode polarization-degenerate and to fine tune the overall mode frequencies, as needed for applications in quantum information science.

  20. A LASER INTERFERENCE-BASED SURFACE TREATMENT OF AL AND CARBON FIBER POLYMER COMPOSITES FOR ENHANCED BONDING

    SciTech Connect

    Sabau, Adrian S; Warren, Charles David; ERDMAN III, DONALD L; Daniel, Claus; Skszek, Timothy; Caruso-Dailey, Mary M.

    2016-01-01

    Due to its increased use in the automotive and aerospace industries, joining of Carbon Fiber-reinforced Polymer matrix Composites (CFPC) to metals demands enhanced surface preparation and control of surface morphology prior to joining. In this study, surfaces of both composite and aluminum were prepared for joining using a new laser based technique, in which the laser interference power profile was created by splitting the beam and guiding those beams to the sample surface by overlapping each other with defined angles to each other. Results were presented for the overlap shear testing of single-lap joints made with Al 5182 and CFPC specimens whose surfaces prepared by (a) surface abrasion and solvent cleaning; and (b) laser-interference structured surfaces by rastering with a 4 mm laser beam at approximately 3.5 W power. CFPC specimens of T700S carbon fiber, Prepreg T70 epoxy, 4 or 5 ply thick, 0/90o plaques were used. Adhesive DP810 was used to bond Al and CFPC. The bondline was 0.25mm and the bond length was consistent among all joints produced. First, the effect of the laser speed on the joint performance was evaluated by laser-interference structure Al and CFPC surfaces with a beam angle of 3o and laser beam speeds of 3, 5, and 10 mm/s. For this sensitivity study, 3 joint specimens were used per each joint type. Based on the results for minimum, maximum, and mean values for the shear lap strength and maximum load for all the 9 joint types, two joint types were selected for further evaluations. Six additional joint specimens were prepared for these two joint types in order to obtain better statistics and the shear test data was presented for the range, mean, and standard deviation. The results for the single-lap shear tests obtained for six joint specimens, indicate that the shear lap strength, maximum load, and displacement at maximum load for those joints made with laser-interference structured surfaces were increased by approximately 14.8%, 16%, and 100

  1. Thermal treatment effects on laser surface remelting duplex stainless steel

    NASA Astrophysics Data System (ADS)

    do Nascimento, Alex M.; Ierardi, Maria Clara F.; Aparecida Pinto, M.; Tavares, Sérgio S. M.

    2008-10-01

    In this paper the microstructural changes and effects on corrosion resistance of duplex stainless steels UNS S32304 and UNS S32205, commonly used by the petroleum industry, were studied, following the execution of laser surface remelting (LSM) and post-thermal treatments (TT). In this way, data was obtained, which could then be compared with the starting condition of the alloys. In order to analyze the corrosion behaviour of the alloys in the as-received conditions, treated with laser and after post-thermal treatments, cyclic polarization tests were carried out. A solution of 3.5% NaCl (artificial sea water) was used, as duplex stainless steels are regularly used by the petroleum industry in offshore locations. The results obtained showed that when laser surface treated, due to rapid resolidification, the alloys became almost ferritic, and since the level of nitrogen in the composition of both alloys is superior to their solubility limit in ferrite, a precipitation of Cr2N (chromium nitrides) occurred in the ferritic matrix, causing loss of corrosion resistance, thus resulting in an increase in surface hardness. However, after the post-thermal treatment the alloys corrosion resistance was restored to values close to those of the as-received condition.

  2. Angle-resolved photoemission extended fine structure of the Ni 3p, Cu 3s, and Cu 3p core levels of the respective clean (111) surfaces

    SciTech Connect

    Huff, W.R. |; Chen, Y.; Kellar, S.A.; Moler, E.J. |; Hussain, Z.; Huang, Z.Q.; Zheng, Y.; Shirley, D.A.

    1997-07-01

    We report a non-s initial-state angle-resolved photoemission extended fine-structure (ARPEFS) study of clean surfaces for the purpose of further understanding the technique. The surface structure sensitivity of ARPEFS applied to clean surfaces and to arbitrary initial states is studied using normal photoemission data taken from the Ni 3p core levels of a Ni(111) single crystal and the Cu 3s and the Cu 3p core levels of a Cu(111) single crystal. The Fourier transforms of these clean surface data are dominated by backscattering. Unlike the s initial-state data, the p initial-state data show a peak in the Fourier transform corresponding to in-plane scattering from the six nearest neighbors to the emitter. Evidence was seen for single-scattering events from the same plane as the emitters and double-scattering events. Using a recently developed, multiple-scattering calculation program, ARPEFS data from clean surfaces and from p initial states can be modeled to high precision. Although there are many layers of emitters when measuring photoemission from a clean surface, test calculations show that the ARPEFS signal is dominated by photoemission from atoms in the first two crystal layers. Thus ARPEFS applied to clean surfaces is sensitive to surface reconstruction. The best-fit calculation for clean Ni(111) indicates an expansion of the first two layers. {copyright} {ital 1997} {ital The American Physical Society}

  3. In-Situ Cleaning of Metal Photo-Cathodes in rf Guns

    SciTech Connect

    Schmerge, J.F.; Castro, J.M.; Clendenin, J.E.; Colby, E.R.; Dowel, D.H.; Gierman, S.M.; Loos, H.; Nalls, M.; White, W.E.; /SLAC

    2007-01-03

    Metal cathodes installed in rf guns typically exhibit much lower quantum efficiency than the theoretical limit. Experimenters often use some sort of in situ technique to ''clean'' the cathode to improve the QE. The most common technique is laser cleaning where the laser is focused to a small spot and scanned across the cathode surface. However, since the laser is operated near the damage threshold, it can also damage the cathode and increase the dark current. The QE also degrades over days and must be cleaned regularly. We are searching for a more robust cleaning technique that cleans the entire cathode surface simultaneously. In this paper we describe initial results using multiple techniques such as several keV ion beams, glow discharge cleaning and back bombarding electrons. Results are quantified in terms of the change in QE and dark current.

  4. A Hybrid Laser Surface Treatment for Refurbishment of Stress Corrosion Cracking Damaged 304L Stainless Steel

    NASA Astrophysics Data System (ADS)

    Gupta, R. K.; Sundar, R.; Kumar, B. Sunil; Ganesh, P.; Kaul, R.; Ranganathan, K.; Bindra, K. S.; Kain, V.; Oak, S. M.; Kukreja, L. M.

    2015-06-01

    The paper describes a new hybrid laser surface treatment approach, combining laser surface melting and laser shock peening treatments, for refurbishment stress corrosion cracking damaged type 304L stainless steel specimens. Hybrid laser surface treatment produced crack-free compressively stressed surface. With respect to as-machined specimens, laser-rejuvenated specimens demonstrated significantly reduced susceptibility to stress corrosion cracking in chloride environment with minor increase in mean surface roughness. The results of the study, although particularly applicable to shallow stress corrosion cracking damage, are important for life extension of in-service stainless steel components operating in corrosive chloride environment.

  5. Cost effective nanostructured copper substrates prepared with ultrafast laser pulses for explosives detection using surface enhanced Raman scattering

    NASA Astrophysics Data System (ADS)

    Hamad, Syed; Podagatlapalli, G. Krishna; Mohiddon, Md. Ahamad; Soma, Venugopal Rao

    2014-06-01

    Ultrafast laser pulses induced surface nanostructures were fabricated on a copper (Cu) target through ablation in acetone, dichloromethane, acetonitrile, and chloroform. Surface morphological information accomplished from the field emission scanning electron microscopic data demonstrated the diversities of ablation mechanism in each case. Fabricated Cu substrates were utilized exultantly to investigate the surface plasmon (localized and propagating) mediated enhancements of different analytes using surface enhance Raman scattering (SERS) studies. Multiple utility of these substrates were efficiently demonstrated by collecting the SERS data of Rhodamine 6G molecule and two different secondary explosive molecules such as 5-amino-3-nitro-l,2,4-triazole and trinitrotoluene on different days which were weeks apart. We achieved significant enhancement factors of >105 through an easily adoptable cleaning procedure.

  6. Cost effective nanostructured copper substrates prepared with ultrafast laser pulses for explosives detection using surface enhanced Raman scattering

    SciTech Connect

    Hamad, Syed; Podagatlapalli, G. Krishna; Soma, Venugopal Rao E-mail: soma-venu@yahoo.com; Mohiddon, Md. Ahamad

    2014-06-30

    Ultrafast laser pulses induced surface nanostructures were fabricated on a copper (Cu) target through ablation in acetone, dichloromethane, acetonitrile, and chloroform. Surface morphological information accomplished from the field emission scanning electron microscopic data demonstrated the diversities of ablation mechanism in each case. Fabricated Cu substrates were utilized exultantly to investigate the surface plasmon (localized and propagating) mediated enhancements of different analytes using surface enhance Raman scattering (SERS) studies. Multiple utility of these substrates were efficiently demonstrated by collecting the SERS data of Rhodamine 6G molecule and two different secondary explosive molecules such as 5-amino-3-nitro-l,2,4-triazole and trinitrotoluene on different days which were weeks apart. We achieved significant enhancement factors of >10{sup 5} through an easily adoptable cleaning procedure.

  7. Development of Statistical Process Control Methodology for an Environmentally Compliant Surface Cleaning Process in a Bonding Laboratory

    NASA Technical Reports Server (NTRS)

    Hutchens, Dale E.; Doan, Patrick A.; Boothe, Richard E.

    1997-01-01

    Bonding labs at both MSFC and the northern Utah production plant prepare bond test specimens which simulate or witness the production of NASA's Reusable Solid Rocket Motor (RSRM). The current process for preparing the bonding surfaces employs 1,1,1-trichloroethane vapor degreasing, which simulates the current RSRM process. Government regulations (e.g., the 1990 Amendments to the Clean Air Act) have mandated a production phase-out of a number of ozone depleting compounds (ODC) including 1,1,1-trichloroethane. In order to comply with these regulations, the RSRM Program is qualifying a spray-in-air (SIA) precision cleaning process using Brulin 1990, an aqueous blend of surfactants. Accordingly, surface preparation prior to bonding process simulation test specimens must reflect the new production cleaning process. The Bonding Lab Statistical Process Control (SPC) program monitors the progress of the lab and its capabilities, as well as certifies the bonding technicians, by periodically preparing D6AC steel tensile adhesion panels with EA-91 3NA epoxy adhesive using a standardized process. SPC methods are then used to ensure the process is statistically in control, thus producing reliable data for bonding studies, and identify any problems which might develop. Since the specimen cleaning process is being changed, new SPC limits must be established. This report summarizes side-by-side testing of D6AC steel tensile adhesion witness panels and tapered double cantilevered beams (TDCBs) using both the current baseline vapor degreasing process and a lab-scale spray-in-air process. A Proceco 26 inches Typhoon dishwasher cleaned both tensile adhesion witness panels and TDCBs in a process which simulates the new production process. The tests were performed six times during 1995, subsequent statistical analysis of the data established new upper control limits (UCL) and lower control limits (LCL). The data also demonstrated that the new process was equivalent to the vapor

  8. Laser removal of sludge from steam generators

    DOEpatents

    Nachbar, Henry D.

    1990-01-01

    A method of removing unwanted chemical deposits known as sludge from the metal surfaces of steam generators with laser energy is provided. Laser energy of a certain power density, of a critical wavelength and frequency, is intermittently focused on the sludge deposits to vaporize them so that the surfaces are cleaned without affecting the metal surface (sludge substrate). Fiberoptic tubes are utilized for laser beam transmission and beam direction. Fiberoptics are also utilized to monitor laser operation and sludge removal.

  9. Surface plasmon resonance assisted rapid laser joining of glass

    SciTech Connect

    Zolotovskaya, Svetlana A.; Tang, Guang; Abdolvand, Amin; Wang, Zengbo

    2014-08-25

    Rapid and strong joining of clear glass to glass containing randomly distributed embedded spherical silver nanoparticles upon nanosecond pulsed laser irradiation (∼40 ns and repetition rate of 100 kHz) at 532 nm is demonstrated. The embedded silver nanoparticles were ∼30–40 nm in diameter, contained in a thin surface layer of ∼10 μm. A joint strength of 12.5 MPa was achieved for a laser fluence of only ∼0.13 J/cm{sup 2} and scanning speed of 10 mm/s. The bonding mechanism is discussed in terms of absorption of the laser energy by nanoparticles and the transfer of the accumulated localised heat to the surrounding glass leading to the local melting and formation of a strong bond. The presented technique is scalable and overcomes a number of serious challenges for a widespread adoption of laser-assisted rapid joining of glass substrates, enabling applications in the manufacture of microelectronic devices, sensors, micro-fluidic, and medical devices.

  10. Laser modification of ceramic surfaces with micro- and nano- particles

    NASA Astrophysics Data System (ADS)

    Rohde, Magnus

    2007-02-01

    Laser supported processes can be used to modify the electrical and thermal properties of ceramic substrates locally. These processes are characterised by a strong thermal interaction between the laser beam and the ceramic surface which leads to localised melting. During the dynamic melting process metal particles are introduced into the melt pool in order to modify the physical properties. Different alumina samples were treated with metal powders of tungsten, copper, and oxides of these metals. The interface between the metal and the ceramic can be designed by using selected combinations of metal- and metal-oxide-powders and also by a thermal post-processing. The application of nano-particles during the laser-dispersing process resulted in completely different characteristics of the micro-structure and the electrical properties compared to the conventional metal powders with an average grain size of 5 - 15 microns. The micron sized metal particles are embedded within the ceramic matrix as particle agglomerates or as distinct metal phase the nano-particle phase covers the grain boundaries of the ceramics leading to network of nano-scaled electrically conducting "wires". The resulting resistance of the laser tracks can be adjusted from semi-conducting to metallic behavior with a resistivity down to 2x10 -6W/m. The modified ceramic can be used for heating elements working at operation temperatures of up to 1000 °C, high current resistances which can be loaded with currents of up to 100 A.

  11. Laser imaging of small surface vessels and people at sea

    NASA Astrophysics Data System (ADS)

    Steinvall, Ove; Elmqvist, Magnus; Karlsson, Kjell; Larsson, Håkan; Axelsson, Maria

    2010-04-01

    The development of new asymmetric threats to civilian and naval ships has been a relatively recent occurrence. The bombing of the USS Cole is one example and the pirate activities outside Somalia another. There is a need to recognize targets at long ranges and possibly also their intentions to prepare for counteractions. Eye safe laser imaging at 1.5 μm offers target recognition at long ranges during day and night. The 1.5 μm wavelength is suitable for observing small targets at the sea surface such as boats and swimmers due to the low reflectivity of water compared to potential targets. Turbulence and haze limits the sensor performance and their influence is estimated for some cases of operational interest. For comparison, passive EO images have been recorded with the same camera to investigate the difference between sun illuminated and laser illuminated images. Examples of laser images will be given for a variety of targets and external conditions.Image segmentation for future automated recognition development is described and examplified. Examples of relevant 1.5 μm laser reflectivities of small naval targets are also presented. Finally a discussion of system aspects is made.

  12. Integrated high-order surface diffraction gratings for diode lasers

    NASA Astrophysics Data System (ADS)

    Zolotarev, V. V.; Leshko, A. Yu; Pikhtin, N. A.; Slipchenko, S. O.; Sokolova, Z. N.; Lubyanskiy, Ya V.; Voronkova, N. V.; Tarasov, I. S.

    2015-12-01

    High-order surface diffraction gratings acting as a distributed Bragg reflector (DBR) in mesa stripe semiconductor lasers (λ = 1030 nm) have been studied theoretically and experimentally. Higher order interfering radiation modes (IRMs), which propagate off the plane of the waveguide, have been shown to have a crucial effect on the reflection and transmission spectra of the DBR. The decrease in the reflectivity of the DBR in response to the increase in the diffraction efficiency of these modes may reach 80% and more. According to theoretical analysis results, the intensity of the higher order IRMs is determined by the geometry of the DBR groove profile. Experimental data demonstrate that the noncavity modes are responsible for parasitic light leakage losses in the laser cavity. It has been shown that, in the case of nonoptimal geometry of the grating groove profile, the overall external differential quantum efficiency of the parasitic laser emission may exceed 45%, which is more than half of the laser output power. The optimal geometry of the DBR groove profile is trapezoidal, with the smallest possible lower base. Experimental evidence has been presented that this geometry considerably reduces the power of the higher order IRMs and minimises the parasitic light leakage loss.

  13. Laser-Based Transient Surface Acceleration of Thermoelastic Layers

    NASA Astrophysics Data System (ADS)

    CETINKAYA, CETIN; WU, CUNLI; LI, CHEN

    2000-03-01

    The removal of particles from elastic substrates has been an important practical problem in the electronics industry especially as the sizes of electronic units shrink. In recent years, there has been an interest in removingsubmicron level particles from surfaces. The use of traditional surface cleaning methods, such as ultrasonically induced fluid flow, vibrational methods, centrifugal techniques, is limited to particles that require surface acceleration lower than 107m/s2. For the effective removal of submicron particles, a higher level surface acceleration is needed since the adhesion forces (mainly van der Waals force for dry surfaces) are related to the particle size and increase approximately linearly as the characteristic radius of small particles that are to be removed decreases. In current work, based on the generalized dynamic theory of thermoelasticity reported, a transfer matrix formulation including the second sound effect is developed for a thermoelastic layer. The transfer matrix for axisymmetric wave propagation in a thermoelastic layer is obtained by adopting a double integral transform approach. The second sound effect is included to eliminate the thermal wave travelling with infinite velocity as predicted by the diffusion heat transfer model, and, consequently, the immediate arrival of waves. Using the current formulation and the periodic systems framework, a transfer function formulation for calculating the accelerations is developed for transient analysis. A double integral transform inversion method is used for transient response calculations. Acceleration levels, sufficient for submicron particle removal, are reported. Various processes such as thermoelastic stresses, surface evaporation, and optical breakdown may be responsible for surface acceleration components and particle removal. In current work, only the surface acceleration due to transient thermoelastic wave propagation is under investigation.

  14. Laser spectrum detection methods for substance of Mars surface

    NASA Astrophysics Data System (ADS)

    Zhang, Dan; Xue, Bin; Zhao, Yi-yi

    2014-11-01

    The chemical element and mineral rock's abundance and distribution are the basic material of planetary geology evolution research [1], hence preterit detection for composition of Mars surface substance contains both elements sorts and mineral ingredients. This article introduced new ways to detect Mars elements and mineral components, Laser Induced Breakdown Spectroscopy (LIBS) and Raman Spectroscopy (RS) which have distinct advantages, such as work over a long distance, detect rapidly, accuratly and nondestructively. LIBS and RS both use laser excitation to shoot the substance of Mars exciting new wavelengths. The techniques of LIBS and RS in laboratory are mature, besides the technique of LIBS is being used in MSL (Chemcam) now and RS will be used in ExoMars. Comparing LIBS and RS's detection results with XRF and APXS, Mossbauer spectrometer, these existed Mars surface material detection instruments,and the Infrared spectrometer, Mid-IR, they have more accurate detection results. So LIBS and RS are competent for Mars surface substance detection instead of X-ray spectrometer and Mossbauer spectrometer which were already used in 'Viking 1' and 'Opportunity'. Only accurate detection results about Mars surface substance can lead to scientist's right analysis in inversing geological evolution of the planet.

  15. Virtual environment assessment for laser-based vision surface profiling

    NASA Astrophysics Data System (ADS)

    ElSoussi, Adnane; Al Alami, Abed ElRahman; Abu-Nabah, Bassam A.

    2015-03-01

    Oil and gas businesses have been raising the demand from original equipment manufacturers (OEMs) to implement a reliable metrology method in assessing surface profiles of welds before and after grinding. This certainly mandates the deviation from the commonly used surface measurement gauges, which are not only operator dependent, but also limited to discrete measurements along the weld. Due to its potential accuracy and speed, the use of laser-based vision surface profiling systems have been progressively rising as part of manufacturing quality control. This effort presents a virtual environment that lends itself for developing and evaluating existing laser vision sensor (LVS) calibration and measurement techniques. A combination of two known calibration techniques is implemented to deliver a calibrated LVS system. System calibration is implemented virtually and experimentally to scan simulated and 3D printed features of known profiles, respectively. Scanned data is inverted and compared with the input profiles to validate the virtual environment capability for LVS surface profiling and preliminary assess the measurement technique for weld profiling applications. Moreover, this effort brings 3D scanning capability a step closer towards robust quality control applications in a manufacturing environment.

  16. Thermal annealing of laser damage precursors on fused silica surfaces

    SciTech Connect

    Shen, N; Miller, P E; Bude, J D; Laurence, T A; Suratwala, T I; Steele, W A; Feit, M D; Wang, L L

    2012-03-19

    Previous studies have identified two significant precursors of laser damage on fused silica surfaces at fluenes below {approx} 35 J/cm{sup 2}, photoactive impurities in the polishing layer and surface fractures. In the present work, isothermal heating is studied as a means of remediating the highly absorptive, defect structure associated with surface fractures. A series of Vickers indentations were applied to silica surfaces at loads between 0.5N and 10N creating fracture networks between {approx} 10{micro}m and {approx} 50{micro}m in diameter. The indentations were characterized prior to and following thermal annealing under various times and temperature conditions using confocal time-resolved photo-luminescence (CTP) imaging, and R/1 optical damage testing with 3ns, 355nm laser pulses. Significant improvements in the damage thresholds, together with corresponding reductions in CTP intensity, were observed at temperatures well below the glass transition temperature (T{sub g}). For example, the damage threshold on 05.N indentations which typically initiates at fluences <8 J/cm{sup 2} could be improved >35 J/cm{sup 2} through the use of a {approx} 750 C thermal treatment. Larger fracture networks required longer or higher temperature treatment to achieve similar results. At an annealing temperature > 1100 C, optical microscopy indicates morphological changes in some of the fracture structure of indentations, although remnants of the original fracture and significant deformation was still observed after thermal annealing. This study demonstrates the potential of using isothermal annealing as a means of improving the laser damage resistance of fused silica optical components. Similarly, it provides a means of further understanding the physics associated with optical damage and related mitigation processes.

  17. Comparative Mirror Cleaning Study: 'A Study on Removing Particulate Contamination'

    NASA Technical Reports Server (NTRS)

    Houston, Karrie

    2007-01-01

    The cleanliness of optical surfaces is recognized as an industry-wide concern for the performance of optical devices such as mirrors and telescopes, microscopes and lenses, lasers and interferometers, and prisms and optical filters. However, no standard has been established for optical cleaning and there is no standard definition of a 'clean' optical element. This study evaluates the effectiveness of commonly used optical cleaning techniques based on wafer configuration, contamination levels, and the number and size of removed particles. It is concluded that cleaning method and exposure time play a significant factor in obtaining a high removal percentage. The detergent bath and solvent rinse method displayed an increase in effective removal percentage as the contamination exposure increased. Likewise, CO2 snow cleaning showed a relatively consistent cleaning effectiveness. The results can help ensure mission success to flight projects developed for the NASA Origins Program. Advantages and disadvantages of each of the optical cleaning methods are described.

  18. Effect of organic matter addition to the pen surface and pen cleaning frequency on nitrogen mass balance in open feedlots.

    PubMed

    Adams, J R; Farran, T B; Erickson, G E; Klopfenstein, T J; Macken, C N; Wilson, C B

    2004-07-01

    Three finishing trials were conducted to determine the effects of dietary manipulation and management on N losses from open feedlots. In each experiment, 96 steers were assigned randomly to 12 nutrient balance pens. In Trial 1, calves were fed for 180 d during the winter/spring months; in Trial 2, yearlings were fed for 132 d in the summer. In Trials 1 and 2, N losses from pens were compared directly by adding OM to the pen surface or indirectly by feeding digestible ingredients designed to increase OM excretion. The dietary treatment (BRAN) included 30% corn bran (DM basis) replacing dry-rolled corn. Pens where OM was directly added received sawdust applications (SAWDUST) at a rate to match OM excretion from the BRAN diet. These two treatments were compared with a conventional, 75% dry-rolled corn diet (CON). Because CON and SAWDUST diets were identical, performance for both treatments was similar during Trials 1 and 2. The BRAN diet decreased (P < 0.10) gain efficiency during Trials 1 and 2 by 9.5% relative to CON. Fecal N excretion was greater (P < 0.01) for calves and yearlings when BRAN was fed compared with CON. Adding OM to the pen surface increased (P < 0.01) the amount of N in manure removed from pens and reduced (P < 0.10) N losses in Trial 1. Nitrogen losses were not significantly different among treatments in Trial 2. In Trial 3, calves were fed for 166 d during the winter/spring months. A 2 x 2 factorial design was used to evaluate pen cleaning frequency and diets similar to CON and BRAN. Pens were either cleaned monthly or once at the end of the feeding period. Daily DMI was greater (P = 0.01) and ADG was lower (P < 0.01) when cattle were fed BRAN compared with CON. Responses from all three trials indicate a negative effect of BRAN on gain efficiency. Dietary treatment and cleaning frequency interacted for N balance in the feedlot. Nitrogen losses decreased and manure N increased (P < 0.10) for cattle fed BRAN compared with CON when pens were cleaned

  19. Single-mode operation of mushroom structure surface emitting lasers

    SciTech Connect

    Wang, Y.J.; Dziura, T.G.; Wang, S.C. ); Du, G.; Wang, S. )

    1991-01-01

    Mushroom structure vertical cavity surface emitting lasers with a 0.6 {mu}m GaAs active layer sandwiched by two Al{sub 0.6{sup {minus}}}Ga{sub 0.4}As-Al{sub 0.08}Ga{sub 0.92}As multilayers as top and bottom mirrors exhibit 15 mA pulsed threshold current at 880 nm. Single longitudinal and single transverse mode operation was achieved on lasers with a 5 {mu}m diameter active region at current levels near 2 {times} I{sub th}. The light output above threshold current was linearly polarized with a polarization ratio of 25:1.

  20. Experimental Study of Magnesium Production with Laser for Clean Energy Cycle

    NASA Astrophysics Data System (ADS)

    Sato, Y.; Yabe, T.; Sakurai, Y.; Mohamed, M. S.; Uchida, S.; Baasandash, C.; Ohkubo, T.; Mori, Y.; Sato, H.

    2008-04-01

    A new scheme of generating power called magnesium injection cycle [MAGIC] engine was developed. Magnesium [Mg] and water are put into the chamber and ignited at 500 degree Celsius. Mg reaction with water produces hydrogen [H2] gas. The hydrogen blows out and reacts with oxygen [O2] gas to generate H2O and energy at the exit nozzle. These reactions occur simultaneously and generate thrust. In order to reproduce Mg, the residual MgO is irradiated by focused cw CO2 laser (1000 W) at 20 Pa. Then, high temperature (over 4000 degree Celsius) is exerted in tiny spot thus MgO reduction in equilibrium is achievable. Spectroscopic analysis was conducted on the Mg/MgO vapor under atmospheric condition. The Mg line at 518 nm, MgO line at 500 nm and O+ line were confirmed. This proves that the MgO is dissociated by laser irradiation These experiments confirm that the scheme can be used for magnesium energy cycle system with practical efficiency and large throughput.