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Sample records for laser surface cleaning

  1. Laser surface cleaning

    SciTech Connect

    Freiwald, J.G.; Freiwald, D.A.

    1994-12-31

    The objective of this work is a laboratory demonstration that red-lead primer and two-part epoxy paints can be stripped from concrete and metal surfaces using surface cleaning systems based on pulsed-repetition CO{sub 2} lasers. The three goals are to: (1) demonstrate coatings removal, including surface pore cleaning; (2) demonstrate that there is negligible release of ablated contaminants to the environment; and (3) demonstrate that the process will generate negligible amounts of additional waste compared to competing technologies. Phase 1 involved site visits to RMI and Fernald to assess the cleaning issues for buildings and parts. In addition, Phase 1 included detailed designs of a more powerful system for industrial cleaning rates, including laser, articulating optics, ablated-material capture suction nozzle attached to a horizontal raster scanner for floor cleaning, and filtration system. Some concept development is also being done for using robots, and for parts cleaning. In Phase 2 a transportable 6 kW system will be built and tested, with a horizontal surface scanner for cleaning paint from floors. The laboratory tests will again be instrumented. Some concept development will continue for using robots, and for parts cleaning. This report describes Phase 1 results.

  2. Laser cleaning of metal surfaces

    NASA Astrophysics Data System (ADS)

    Walters, Craig T.; Campbell, Bernard E.; Hull, Robert J.

    1998-09-01

    There is a critical need to replace ozone-depleting substances and hazardous chemicals that, in the past, have been used routinely in aerospace maintenance operations such as precision cleaning of metal surfaces. Lasers now offer the potential for removal of many organic materials from metals without the use of any solvent or aqueous cleaning agents. This paper presents quantitative results of laser-cleaning process-development research with a pulsed Nd:YAG laser and several common metals and organic contaminants. Metal coupons of Stainless Steel 304, Aluminum 5052, and Titanium were contaminated with known amounts of organic oils and greases at contamination levels in the 5 to 200 (mu) g/cm2 range. A fiber-optic-delivered 1064-nm pulsed laser beam (20-Hz repetition rate) was scanned over the coupons with different overlap and pulse fluence conditions. Measurements of mass loss revealed that all levels of initial contamination could be removed to final cleanliness levels less than 3 (mu) g/cm2, at which point the mass loss measurements became uncertain. Pulse fluence thresholds for initial cleaning effects and practical cleaning rates for several metal and contaminant combinations are reported. From the totality of the results, an overall picture of the contaminant removal mechanism is emerging. For semi-transparent films, it is conjectured that a thermo-mechanical effect occurs wherein the laser energy is absorbed predominantly in the metal substrate which expands on the nanosecond time scale. This rapid expansion, in combination with some material evaporation at the film/metal interface, is believed to eject the contaminant film directly into aerosol droplets/particles which can be swept away and collected for recycle or cost- effective disposal in a compact form. Evidence for this mechanism will be presented.

  3. Laser surface cleaning of organic contaminants

    NASA Astrophysics Data System (ADS)

    Feng, Y.; Liu, Z.; Vilar, R.; Yi, X.-S.

    1999-08-01

    Laser surface cleaning process has been a useful and efficient technique for various industrial applications. The removal of photoresist contaminants on silicon wafers was investigated with a krypton fluoride (KrF) excimer laser, and the irradiated area was characterized using a profilometer, a scanning electronic microscopy (SEM), an Auger electron spectroscopy (AES) and a Fourier transition infrared spectroscopy (FT-IR). It was found that there exist an optimal number of pulses to remove the contaminant from the substrate surface without any laser-induced damage, depending on the laser density on the surface. A model to predict the optimal number of pulses, which agrees well with Beer-Lambert's law, is proposed and proved to be operable.

  4. Picosecond Laser Surface Cleaning of AM1 Superalloy

    NASA Astrophysics Data System (ADS)

    Moskal, D.; Martan, J.; Kučera, M.; Houdková, Š.; Kromer, R.

    Laser scanning processing of nickel-based superalloy AM1 surfaces by ultra-short pulses (10 ps) is introduced as a cleaning and deoxidation postprocess. The laser cleaning is investigated with two-directional surface scanning by a laser beam with several frequencies of pulse generation. The EDX elemental analyses of the laser cleaned AM1 surfaces were compared with the non-laser treated surface. The optimal speed, laser pulse repetition frequency, overlapping and layer repetition count are determined for minimal structural changes on the mechanically polished AM1 surfaces. The laser cleaning after shifted laser surface texturing (sLST) is presented as a two-step preparation of a superalloy surface for thermal spraying. The heat accumulation effect and temperature fields are calculated from a semi-planar model of a laser beam scanning heat source. The theoretical results are discussed in comparison with experimental studies. The upper and bottom bounds are defined for an optimal high speed laser cleaning process.

  5. Laser Cleaning of Metal Surface — Laboratory Investigations

    NASA Astrophysics Data System (ADS)

    Mottner, P.; Wiedemann, G.; Haber, G.; Conrad, W.; Gervais, A.

    The interaction of various metal alloys with laser energy generated by a Nd:YAG medium (λ=1064 nm, 532 nm, and 355 nm) has been examined systematically by the variation of laser parameters. With the help of model coupons, alteration/ablation thresholds of uncorroded/corroded surfaces of iron, pure copper and copper alloys were determined, leading to first recommendations for the cleaning of originals. Surface absorption measurements in the UV/VIS/IR wavelength regions completed the interaction studies.

  6. Macroscopic surface cleaning using a high repetition rate ultraviolet laser

    NASA Astrophysics Data System (ADS)

    Pang, H. M.; Baldwin, D.; Edelson, M. C.

    The aim of the Ames Laboratory Laser Decontamination Project is to explore new decontamination methods to reduce waste volumes and achieve sufficiently high decontamination factors to permit the unrestricted release of metals for commercial use. This paper presents a discussion of recent experimental work designed to test the capabilities of ultraviolet lasers for large surface area (approximately m(sup 2)) cleaning. The potential benefits of applying laser technology to decontamination are the elimination of solvents, the potential for remote operation to reduce exposure of personnel and expensive equipment to radiation hazards, and the minimization of secondary wastes. High-repetition rate lasers can clean large surfaces (approximately m(sup 2)) in a reasonable amount of time. Proper selection of laser pulse energy, wavelength, repetition rate, and focusing lens is mandated to optimize process efficiency.

  7. LASER CLEANING OF CONTAMINATED PAINTED SURFACES

    SciTech Connect

    Ames A. Grisanti; Charlene R. Crocker; Robert R. Jensen

    1999-11-19

    Several techniques are available or under development for surface decontamination in nuclear facilities. Each technique has its merits; however, none of them is universally the best choice for all surface decontamination applications. Because of the multitude of factors which influence the environmental and economic aspects of selecting a surface decontamination technique, it is difficult to select the best method in a given situation; an objective basis for comparing techniques is needed. The objective of this project was to develop a software tool for use by personnel selecting a surface decontamination technique. The software incorporates performance data for available surface decontamination techniques. The beta release version of the Surface Decontamination Assistant Software has been completed and has undergone testing at the Energy and Environmental Research Center. Minor modifications to the software were completed, and a final release version of the software is ready to be issued.

  8. 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?

  9. Laser cleaning of the contaminations on the surface of tire mould

    NASA Astrophysics Data System (ADS)

    Ye, Yayun; Jia, Baoshen; Chen, Jing; Jiang, Yilan; Tang, Hongping; Wang, Haijun; Luan, Xiaoyu; Liao, Wei; Zhang, Chuanchao; Yao, Caizhen

    2017-07-01

    During the manufacturing of tires, surface pollutants on tire mould will lead to the production of unqualified tires. Tire moulds need to be regularly cleaned. Laser cleaning is recognized as a non-destructive, effective, precise and environmental friendly method. In this paper, laser cleaning was used to remove contaminants on tire mould surface. First, laser induced damage experiments were performed. The results showed that the roughness and hardness of the cast steel sample surface seldom changed under the energy range of 140.1-580.2 mJ laser irradiation 1 pulse and the energy range of 44.7-168.9 mJ laser irradiation 100 pulses. In the laser cleaning experiments, the cleaning thresholds and the optimal cleaning parameters were obtained. Results indicated that laser cleaning was safe and effective for tire mould contamination removal.

  10. 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

  11. Laser Cleaning of Gildings

    NASA Astrophysics Data System (ADS)

    Panzner, M.; Wiedemann, G.; Meier, M.; Conrad, W.; Kempe, A.; Hutsch, T.

    Results of laser cleaning experiments on different gilding types like leaf gilding and fire gilding are presented in this contribution by means of three tested art objects. The reflectivity of gold is advantageously high for the typical laser cleaning wavelength of 1,064 nm. Additionally, to avoid damage like gold loss, the transfer of the absorbed laser pulse energy into the art object by thermal conduction is considered. Fire gilded surfaces are most easily cleaned because of the good heat transfer conditions which imply a high threshold intensity with respect to damage. This is different for leaf gilded surfaces but suitable laser cleaning parameters have also been found for this case. The results of laser cleaning experiments are presented by photography, microscopy, SEM and EDX analysis.

  12. CO2 laser-cleaning of dimethylsilicone contamination on the surface of gold films

    NASA Astrophysics Data System (ADS)

    Ye, Yayun; Yuan, Xiaodong; Xiang, Xia; Chen, Meng; Miao, Xinxiang; Lv, Haibing; Wang, Haijung; Wang, Chengcheng; Zheng, Wanguo

    2009-08-01

    As a non-contact cleaning method, laser cleaning can effectively remove particulate contaminations of sizes as small as 0.1 μm without damage to the optics. In this work, 10.6 μm CO2 laser was utilized to clean the dimethylsilicone oil contaminated on the surface of the gold-coated K9 glass. The dimethylsilicone oil contaminants with different degree were obtained by 10-30 minutes of vapor condensation. Single point irradiation mode was used to study the removal of the dimethylsilicone oil. The cleaning different degree of contaminations was investigated at the variable laser parameters, including laser power, laser frequency, and irradiation time. Optical microscope was used to analyze the cleaning effect. The results show that CO2 laser can effectively remove the dimethylsilicone oil. On the premise that the gold-coated K9 glasses are not damaged, the cleaning area increases with the increase of radiation time and laser power. The cleaning area doesn't change much with the variation of laser frequency when the other parameters are the same. In addition, at the same laser parameters, the cleaning area increases as contamination degree increases.

  13. 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.

  14. A method for cleaning optical precision surface of laser gyro cavity

    NASA Astrophysics Data System (ADS)

    Cui, Ying; Jiao, Ling Yan; Lin, Na Na; Zhang, Dong

    2016-10-01

    Laser gyro is the only one non-electromechanical high-precision inertial sensitive instruments in aircraft inertial guidance systems. Ultra high vacuum acquisition is a key segment during the manufacturing process of laser gyro. The surface cleanliness and integrity have decisive influence on the sealing performance of ultra-high vacuum. A cleaning technology for the optical surface of laser gyro cavity was found by experiment. Meanwhile, the analysis of the adsorption mechanism of contaminant on the laser gyro cavity surface and overview of common optical element cleaning technology were given. The result showed that the new cleaning technology improved the cleanliness of the cavity optical surface without any damage and provided a reliable solution for chronic leak of high precision laser gyro cavity.

  15. 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.

  16. Lasers and applications in parts cleaning and surface pre-treatment

    NASA Astrophysics Data System (ADS)

    Burdel, Thomas; Weiler, Sascha; Faißt, Birgit; Schneider, Till; Heckl, Oliver; Birkel, Jörn; Luzius, Severin

    2013-02-01

    A number of upcoming industrial applications prove that the laser offers great possibilities for parts cleaning and surface pretreatment. Thereby laser technology enables solutions to reduce production costs and to increase productivity and quality in the manufacturing process. Examples are the removal of oil, grease, phosphate layers or corrosion with the laser. This paper will focus on parts cleaning and surface pretreatment applications within the automotive industry. For a range of examples it will be shown that the laser not only offers advantages to carry out the described production step (such as cleaning or the creation of functional textures) but also offers great advantages for a following production step within the chain, such as a welding or gluing process. It will be demonstrated that several ns and ps laser sources and systems can be selected, depending on the application.

  17. Pulsed laser cleaning of aluminium-magnesium alloys: effect of surface modifications on adhesion

    NASA Astrophysics Data System (ADS)

    Autric, Michel; Oltra, Roland

    2008-05-01

    Surface cleaning is a key step in many industrial processes and especially in laser surface treatments. During laser cleaning of metallic alloys using pulsed lasers, surface modification can be induced due to transient thermal effect. In ambient atmospheric conditions, an oxidation of the cleaned surface can be detected. The aim of this work was to characterize this transient oxidation that can occur below the laser energy domain leading to any phase change (melting, ablation) of the cleaned substrate. A Q-switched Nd:YAG laser (1.06 μm) with 10 ns pulse duration was used for this study. X-ray photoelectron spectroscopy and secondary ion mass spectroscopy were used for surface analysis of irradiated samples. Thermal oxidation took place on the aluminium-magnesium alloy (5000 series) during the irradiation in air (fluence range 0.6-1.4 Jcm-2). It has been demonstrated that this 10 ns laser thermal oxidation and the steady state thermal oxidation have the same mechanism. When the laser fluence reached 1 J cm -2 , the oxide formed by the thermal oxidation became in a large extent crystalline and its outer part was entirely covered by a continuous magnesium oxide layer.

  18. Laser Cleaning of Avian Eggshell

    NASA Astrophysics Data System (ADS)

    Cornish, L.; Ball, A.; Russell, D.

    A low vacuum SEM was used to evaluate the effect of using an Nd:YAG laser as a non-contact technique for cleaning avian eggshells. The technique shows potential, since there are no obvious deleterious effects from cleaning, but further study is required to understand how the laser is interacting with the sample surface.

  19. 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.

  20. 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/.

  1. 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.

  2. The effects of short pulse laser surface cleaning on porosity formation and reduction in laser welding of aluminium alloy for automotive component manufacture

    NASA Astrophysics Data System (ADS)

    AlShaer, A. W.; Li, L.; Mistry, A.

    2014-12-01

    Laser welding of aluminium alloys typically results in porosity in the fusion zones, leading to poor mechanical and corrosion performances. Mechanical and chemical cleaning of surfaces has been used previously to remove contaminants for weld joint preparations. However, these methods are slow, ineffective (e.g. due to hydrogen trapping) or lead to environmental hazards. This paper reports the effects of short pulsed laser surface cleaning on porosity formation and reduction in laser welding of AC-170PX (AA6014) aluminium sheets (coated with Ti/Zr and lubricated using a dry lubricant AlO70) with two types of joints: fillet edge and flange couch, using an AA4043 filler wire for automotive component assembly. The effect of laser cleaning on porosity reduction during laser welding using a filler wire has not been reported before. In this work, porosity and weld fusion zone geometry were examined prior to and after laser cleaning. The nanosecond pulsed Nd:YAG laser cleaning was found to reduce porosity significantly in the weld fusion zones. For the fillet edge welds, porosity was reduced to less than 0.5% compared with 10-80% without laser cleaning. For flange couch welds, porosity was reduced to 0.23-0.8% with laser cleaning from 0.7% to 4.3% without laser cleaning. This has been found to be due to the elimination of contaminations and oxide layers that contribute to the porosity formation. The laser cleaning is based on thermal ablation. This research focuses on porosity reduction in laser welding of aluminium alloy. Weld quality was investigated for two joints, fillet edge and flange couch joints. The effect of laser cleaning on porosity reduction after welding was investigated. It was found that laser cleaning reduced porosity less than 1% in both joints. Weld dimensions and strength were evaluated and discussed for both types of joints.

  3. 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.

  4. 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.

  5. 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.

  6. Laser cleaning on Roman coins

    NASA Astrophysics Data System (ADS)

    Drakaki, E.; Karydas, A. G.; Klinkenberg, B.; Kokkoris, M.; Serafetinides, A. A.; Stavrou, E.; Vlastou, R.; Zarkadas, C.

    Ancient metal objects react with moisture and environmental chemicals to form various corrosion products. Because of the unique character and high value of such objects, any cleaning procedure should guarantee minimum destructiveness. The most common treatment used is mechanical stripping, in which it is difficult to avoid surface damage when employed. Lasers are currently being tested for a wide range of conservation applications. Since they are highly controllable and can be selectively applied, lasers can be used to achieve more effective and safer cleaning of archaeological artifacts and protect their surface details. The basic criterion that motivated us to use lasers to clean Roman coins was the requirement of pulsed emission, in order to minimize heat-induced damages. In fact, the laser interaction with the coins has to be short enough, to produce a fast removal of the encrustation, avoiding heat conduction into the substrate. The cleaning effects of three lasers operating at different wavelengths, namely a TEA CO2 laser emitting at 10.6 μm, an Er:YAG laser at 2.94 μm, and a 2ω-Nd:YAG laser at 532 nm have been compared on corroded Romans coins and various atomic and nuclear techniques have also been applied to evaluate the efficiency of the applied procedure.

  7. Laser cleaning of tungsten ribbon

    NASA Astrophysics Data System (ADS)

    Kumar, Aniruddha; Sonar, V. R.; Das, D. K.; Bhatt, R. B.; Behere, P. G.; Afzal, Mohd.; Kumar, Arun; Nilaya, J. P.; Biswas, D. J.

    2014-07-01

    Removal of a thin oxide layer from a tungsten ribbon was achieved using the fundamental, second and third harmonic radiation from a Q- switched Nd-YAG laser. It was found that beyond the threshold, oxide removal was achieved at all wavelengths for a wide range of fluence values. The removal mechanism of the oxide layer was found to be critically dependent on both wavelength and fluence of the incident radiation and has been identified as ejection or sublimation. The un-cleaned and cleaned surfaces were analyzed by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDS) and atomic force microscopy (AFM). Laser cleaned tungsten ribbons were used in a thermal ionization mass spectrometer (TIMS) to determine isotopic composition of Neodymium atoms.

  8. Colour changes of a historical Gotland sandstone caused by laser surface cleaning in ambient air and N2 flow

    NASA Astrophysics Data System (ADS)

    Jasińska, M.; Nowak, A.; Łukaszewicz, J. W.; Śliwiński, G.

    2008-07-01

    The surface discoloration due to laser cleaning was investigated for a historical Gotland sandstone. The difference in discoloration for cleaning performed in air and in the shielding environment of N2 flowing at low velocities was studied by means of colorimetry and scanning electron microscopy and energy dispersive X-ray spectroscopy techniques. For ablative removal of the natural as well as artificially applied encrustation a pulsed 1064-nm laser operated at a fluence of 0.5 J/cm2 was applied. It was observed that the natural colour variations (ΔL*=21; Δb*=23) of the stone can completely screen the laser-induced changes. Under conditions of shielding with nitrogen, darkening and yellowing slightly stronger than those occurring in the ambient air were revealed for the laser-cleaned, artificially crusted samples and the effect was independent of the gas-flow velocity. The observed difference confirmed the contribution of iron oxidation to the laser-induced yellowing and showed that the presence of oxygen in the ambient air affects favourably the cleaning by supporting removal of a variety of combustible surface remnants and crust components of organic as well as inorganic origin.

  9. Removal of beryllium-containing films deposited in JET from mirror surfaces by laser cleaning

    NASA Astrophysics Data System (ADS)

    Widdowson, A.; Coad, J. P.; Temmerman, G. de; Farcage, D.; Hole, D.; Ivanova, D.; Leontyev, A.; Rubel, M.; Semerok, A.; Schmidt, A.; Thro, P.-Y.; JET-EFDA Contributors

    2011-08-01

    A set of stainless steel (SS) and molybdenum mirror samples located in the divertor and at the outer mid-plane of the vessel were exposed in JET from 2005 to 2007. A selection of these mirror samples with well adhered deposits (i.e. not flaking) of up to a few hundred nanometers in thickness and with Be/C ratios ranging from 0 to ∼1 have been cleaned using a laser system developed at CEA, Saclay. Following laser cleaning the recovered reflectivity was generally better in the infrared than the visible spectrum, with recovery of up to 90% of the initial reflectivity being obtained at 1600 nm for both Mo and SS mirrors falling as low as 20-30% of initial reflectivity at a wavelength of 400 nm for some SS mirrors, rising to ∼80% for Mo mirrors. Some deposit remained on the mirrors after the cleaning trials.

  10. Removal of beryllium-containing films deposited in JET from mirror surfaces by laser cleaning

    NASA Astrophysics Data System (ADS)

    Jet-Efda Contributors Widdowson, A.; Coad, J. P.; Temmerman, G. De; Farcage, D.; Hole, D.; Ivanova, D.; Leontyev, A.; Rubel, M.; Semerok, A.; Schmidt, A.; Thro, P.-Y.

    2011-08-01

    A set of stainless steel (SS) and molybdenum mirror samples located in the divertor and at the outer mid-plane of the vessel were exposed in JET from 2005 to 2007. A selection of these mirror samples with well adhered deposits (i.e. not flaking) of up to a few hundred nanometers in thickness and with Be/C ratios ranging from 0 to ˜1 have been cleaned using a laser system developed at CEA, Saclay. Following laser cleaning the recovered reflectivity was generally better in the infrared than the visible spectrum, with recovery of up to 90% of the initial reflectivity being obtained at 1600 nm for both Mo and SS mirrors falling as low as 20-30% of initial reflectivity at a wavelength of 400 nm for some SS mirrors, rising to ˜80% for Mo mirrors. Some deposit remained on the mirrors after the cleaning trials.

  11. Laser cleaning of printed circuit boards

    NASA Astrophysics Data System (ADS)

    Song, W. D.; Hong, M. H.; Lu, Y. F.; Chong, T. C.

    2003-03-01

    Laser cleaning of printed circuit boards (PCB) has been studied in this paper. It is demonstrated that laser cleaning is a powerful tool to remove resin contaminants from printed circuit boards. A Nd:YAG laser is used as a light source for laser cleaning. The beam profile of the YAG laser is reshaped and homogenized into a square beam with uniform energy distribution in the focal plane of the focusing lens by using an optical system. The printed circuit board surfaces before and after laser cleaning were inspected by an optical microscope, analysed by X-ray photoelectron spectroscopy and monitored by an acoustic wave detection method. The cleaning threshold is about 75 mJ/cm 2 and no damage is observed below 400 mJ/cm 2.

  12. Laser cleaning experimental investigations on ancient coins

    NASA Astrophysics Data System (ADS)

    Drakaki, E.; Evgenidou, D.; Kantarelou, V.; Karydas, A. G.; Katsikosta, N.; Kontou, E.; Serafetinides, A. A.; Vlachou-Mogire, C.

    2008-12-01

    Laser cleaning tests were performed on ancient (Roman and Byzantine) coins, which belong to the collection of the Numismatic Museum of Athens, Greece. Coins with various types of surface corrosion were studied, using Q-switched Nd:YAG, CO2 and Er:YAG lasers and a range of laser pulsing parameters on dry and wet surfaces. A section of each object was cleaned mechanically, by the conservators of the museum in order to show the results of this method. It was discovered that the results of laser cleaning was influenced by the type of corrosion of the surface of the coins. X-ray fluorescence was applied as analytical technique. The results show that XRF could provide detail information about the surface chemical nature of the treated objects, as well as about their past and present state and it leaded to recommendations for restoration with the appropriate laser cleaning conditions.

  13. Research of laser cleaning technology for steam generator tubing

    NASA Astrophysics Data System (ADS)

    Hou, Suixa; Luo, Jijun; Xu, Jun; Yuan, Bo

    2010-10-01

    Surface cleaning based on the laser-induced breakdown of gas and subsequent shock wave generation can remove small particles from solid surfaces. Accordingly, several studies in steam generator tubes of nuclear power plants were performed to expand the cleaning capability of the process. In this work, experimental apparatus of laser cleaning was designed in order to clean heat tubes in steam generator. The laser cleaning process is monitored by analyzing acoustic emission signal experimentally. Experiments demonstrate that laser cleaning can remove smaller particles from the surface of steam generator tubes better than other cleaning process. It has advantages in saving on much manpower and material resource, and it is a good cleaning method for heat tubes, which can be real-time monitoring in laser cleaning process of heat tubes by AE signal. As a green cleaning process, laser cleaning technology in equipment maintenance will be a good prospect.

  14. Influence of beam incidence angle on dry laser cleaning of surface particles

    NASA Astrophysics Data System (ADS)

    Vereecke, G.; Röhr, E.; Heyns, M. M.

    2000-03-01

    Dry laser cleaning is envisaged by semiconductor companies to replace wet-cleans. The influence of beam incidence angle was studied in the case of the removal of weakly absorbing particles on absorbing Si wafers by 248 nm DUV light pulses. By decreasing the beam incidence angle from 80° to 10°, the removal efficiency of 0.15-0.30 μm Si 3N 4 particles was increased by 30-45%, while no improvement was observed with 0.3 μm SiO 2 particles. Based on theoretical calculations, it is proposed that the enhanced removal of particles at grazing incidence is caused by the horizontal component of the beam radiation pressure. The difference between Si 3N 4 and SiO 2 particles is attributed to the influence of particle shape on van der Waals adhesion forces.

  15. Laser cleaning of graffiti on stone

    NASA Astrophysics Data System (ADS)

    Atanassova, Victoria; Kostadinov, Ivan; Zahariev, Peter; Grozeva, Margarita; Miloushev, Ilko

    2016-01-01

    In present days graffiti is a common problem that many restorers have to deal with due to both its unaesthetic appearance and damaging nature for the surface beneath. We report laser cleaning of graffiti paints (black, white, blue, green and red) on limestone and granite. The efficiency of two laser systems is compared: high repetition rate (20 kHz) Copper Bromide Vapor Laser (CuBrVL) generating wavelength 510.6 nm and low repetition rate (up to 10 Hz) Q-switched Nd:YAG laser generating fundamental wavelength 1064 nm and its second harmonic 532 nm. The surface condition of the stone samples before and after cleaning is evaluated by means of optical microscopy. On that base, suitable working parameters are chosen in order to avoid under- or over-cleaning.

  16. 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.

  17. 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.

  18. 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. PMID:27873884

  19. Pulsed U.V. Laser Cleaning Of GaSb Single Crystal Surface In Ultra-High-Vacuum

    NASA Astrophysics Data System (ADS)

    Petit, E. J.; Humblet, V. M.; Brezini, A.; Caudano, R.; Gouskov, A.; Bougnot, G.

    1989-01-01

    Surface modifications induced to GaSb single crystals by pulsed U.V. laser annealing (PLA) in ultra-high-vacuum have been studied. The (111) surfaces of GaSb single crystals were prepared by a mechanical and chemical etching before introducing into vacuum. The samples were subsequently exposed in vacuum to the U.V. radiation (193 nm) of an high power excimer laser. The analysis by Auger electron spectroscopy performed in situ shows that an atomically clean surface (free of native oxides and of carbon pollution) can be achieved by PLA. The effects of the Energy Density (ED) and of the repetition of the PLA are addressed. Superficial topology changes observed in situ by low resolution scanning electron microscopy, and later by optical microscopy, are described too. From our observations we conclude that She antimony oxides begin to decompose noticely when the surface is irradiated with 50 mJ/cm2 laser pulses. Their evaporation explains the onset of the sharp chemical reduction observed at higher fluences. We propose that superficial melting of the GaSb single crystal starts as soon as the laser beam ED reaches 100 mJ/cm . Beyond this fluence the superficial chemical reduction is completed not only by evaporation, but also : - first : by thermal stress induced fracture of the gallium oxide layer and its ejection due to the strong evaporation from the substrate, and, - second : by the gallium oxide dissolution into the melt. The amount of antimony segregated on ple surface becomes important when the surface melts deeply (i.e. at ED superior of 150 mJ/cm2).

  20. 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.

  1. Task 12: Laser cleaning of contaminated painted surfaces. Semi-annual report, April 1, 1996--September 30, 1996

    SciTech Connect

    Grisanti, A.A.; Hassett, D.J.

    1997-05-01

    Paint contaminated with radionuclides and other hazardous materials is common in Department of Energy (DOE) facilities. Facility decommissioning and decontamination requires the removal of contaminated paint. Paint removal technologies include laser- and abrasive-based systems. F2 Associates are utilizing a pulsed-repetition CO{sub 2} laser that produces a 2.5-cm x 2.5-cm beam which can be scanned across a 30- x 100-cm raster and, when placed on a robot, can be designed to clean any surface that the robot can be programmed to follow. Causing little or no damage to the substrate (concrete, steel, etc.), the laser ablates the material to be removed from a given surface. Ablated material is then pulled into a filtration and collection (VAC-PAC) system to prevent the hazardous substances from entering into the atmosphere. The VAC-PAC system deposits the ablated material into waste drums which may be removed from the system without compromising the integrity of the seal, allowing a new drum to be set up for collection without leakage of the ablated material into the atmosphere.

  2. Laser cleaning of steel for paint removal

    NASA Astrophysics Data System (ADS)

    Chen, G. X.; Kwee, T. J.; Tan, K. P.; Choo, Y. S.; Hong, M. H.

    2010-11-01

    Paint removal is an important part of steel processing for marine and offshore engineering. For centuries, a blasting techniques have been widely used for this surface preparation purpose. But conventional blasting always has intrinsic problems, such as noise, explosion risk, contaminant particles, vibration, and dust. In addition, processing wastes often cause environmental problems. In recent years, laser cleaning has attracted much research effort for its significant advantages, such as precise treatment, and high selectivity and flexibility in comparison with conventional cleaning techniques. In the present study, we use this environmentally friendly technique to overcome the problems of conventional blasting. Processed samples are examined with optical microscopes and other surface characterization tools. Experimental results show that laser cleaning can be a good alternative candidate to conventional blasting.

  3. 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.

  4. Lasers Cleaning of Patrimonial Plasters

    NASA Astrophysics Data System (ADS)

    Tanguy, E.; Huet, N.; Vinçotte, A.

    The use of the lasers Q-switched Nd:YAG to remove the dust of the stone monuments especially sculpture gradually replaces the more abrasive technique of sandblasting. This tendency made us consider the lasers as solution for the cleaning of ceramics and the plasters. Indeed in museums, these materials are often covered with dirty mark (dust, grease, etc.) which is difficult to remove without damaging the object. This paper deals with the impact of different types of lasers (Nd:YAG first and third harmonic) irradiation on plaster and with the effects on its morphology and its crystallography. Plaster is an interesting material because of its typical acicular crystals altered at low temperature. That is why synthesis samples were prepared, constrained in temperature then analysed by various processes (SEM, XRD, TGA. . . ). These results were compared with samples cleaned by laser. That enabled us to conclude that plasters cleaned by UV-laser (third harmonic of the Nd:YAG) underwent neither yellowing, nor morphological or crystallographic changes. It has to be opposed to the intense yellowing, and sometimes morphological destruction, which appears with an infrared wavelength (first harmonic of the Nd:YAG).

  5. Chemical-free cleaning using excimer lasers

    NASA Astrophysics Data System (ADS)

    Lizotte, Todd E.; O'Keeffe, Terence R.

    1996-04-01

    A critical requirement in many industrial processes is the cleaning of oils and grease, oxides, solvent residues, particles, thin films and other contaminants from surfaces. There is a particularly acute need in the electronics industry for cleaning semiconductor wafers and computer chips and in the metals industry for removing oxides and other contaminants. Cleaning traditionally is done by various wet chemical processes, almost all consuming large amounts of water and producing large amounts of hazardous wastes. To further complicate this, some of these cleaning agents and vast water consumption are undergoing stringent restrictions. The Radiance ProcessSM is a novel, patented Excimer Laser approach to dry surface cleaning. The process has removed particles from 80 microns to submicron sizes, paints, inks, oxides, fingerprints, hazes, parts of molecules and metallic ions in fingerprints. The process does not ablate, melt or damage the underlying surface. Micro-roughening on some Silicon and Gallium Arsenide is on the order of 1A or less. This paper will discuss the various applications with this process and the latest results from a beta wafer cleaning prototype test bed system that is being built under an EPA grant and joint partnership between Radiance Services Company, Neuman Micro Technologies, Inc. and the Microelectronics Research Laboratory.

  6. 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.

  7. Laser Cleaning of Contaminated Painted Surfaces. Semiannual report, November 1, 1996--March 31, 1997

    SciTech Connect

    Grisanti, Ames A.; Jensen, Robert R.

    1997-12-31

    The objective of this project is to develop a software tool for use by personnel who must select a surface decontamination technique. The software will incorporate performance data for available surface decontamination techniques. The major activities in the project are broken down as follows: Task 1 - Complete decision tree development. Task 2 - Literature search for surface decontamination reports. Task 3 - Compilation of database from literature data. Task 4 - Sensitivity analysis and model design. Task 5 - Design of model data structures. Task 6 - PC software design and coding

  8. 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.

  9. Laser cleaning of calcareous stones: influence of laser irradiation in colour changes of different layers

    NASA Astrophysics Data System (ADS)

    Amaral, Sandra S.; Pires, Margarida; Carvalho, M. D.; Costa, F. M.

    2008-10-01

    Experimental laser cleaning of black crusted calcareous stones, carried on to study the laser yellowing of petreous surfaces, showed different colour alterations on the exposed surface, after laser irradiation, depending not only on the incident fluence but also with the crust or stone irradiated layer.

  10. 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.

  11. Laser cleaning of varnishes and contaminants on brass

    NASA Astrophysics Data System (ADS)

    Mateo, M. P.; Ctvrtnickova, T.; Fernandez, E.; Ramos, J. A.; Yáñez, A.; Nicolas, G.

    2009-03-01

    The capability of laser ablation to perform controlled cleaning of varnishes containing contaminants and paints used by restorers in artistic objects from brass samples while keeping unaltered the finish structure is demonstrated in this work. Adequate laser energy per pulse and number of laser shots required to perform a suitable cleaning by laser ablation have been optimized. The inspection of the samples before and after the cleaning process by optical microscopy and by Fourier transform infrared spectroscopy (FTIR) technique demonstrated that the finish structure of the surface was intact while the coatings were completely eliminated. Furthermore, a laser-induced plasma spectroscopy (LIBS)-based detection system was applied during the irradiation process for the analysis of the material removal and also for its monitoring.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Cleaning with water decomposed products obtained by laser irradiation

    NASA Astrophysics Data System (ADS)

    Hidai, Hirofumi; Tokura, Hitoshi

    2006-11-01

    ArF excimer laser irradiation can decompose water, and decomposed products contain highly reactive substrates, such as radicals. We propose cleaning using pure water with the aid of water decomposed products obtained by ArF excimer laser irradiation. In this study, the oxidation potential of decomposed products was estimated in metal etching. Then, cleaning of cutting oil was examined. The focal point of the lens used was set at the water surface. Specimens were aligned parallel to the laser beam, so that only decomposed products affected contaminants. As a result, decomposed products could not etch nickel and copper plates, but only zinc plates. Cutting oil was cleaned after 18 000 irradiation pulses. The range of the region cleaned was 5 mm around the focal point.

  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. Laser paper cleaning: the method of cleaning historical books

    NASA Astrophysics Data System (ADS)

    Zekou, Evangelini; Tsilikas, Ioannis; Chatzitheodoridis, Elias; Serafetinides, Alexander A.

    2016-01-01

    Conservation of cultural heritage treasures is the most important issue for transferring knowledge to the public through the next generation of students, academics, and researchers. Although this century is authenticating e-books and information by means of electronic text, still historical manuscripts as content as well as objects are the main original recourses of keeping a record of this transformation. The current work focuses on cleaning paper samples by the application of pulsed light, which is interventional. Experiments carried out using paper samples that are artificially colonized with Ulocladium chartarum. Paper is treated by Nd:YAG laser light. The available wavelength is 1064 nm, at various fluences, repetition rates and number of pulses. Two types of paper are stained with fungi colonies, which grow on substrates of clean paper, as well as on paper with ink text. The first type of paper is Whatman No.1056, which is closer to pure cellulose. The second type of paper is a page of a cultural heritage book published in 1926. Cleaning is performed using laser irradiation, thus defining the damage threshold of each sample. The treatment on paper Watman showed a yellowing, especially on areas with high concentration of fungi. The second sample was more durable to the exposure, performing the best results at higher fluences. Eventually, the paper samples are characterized, with optical microscopy and SEM/EDX analyses, prior to and after cleaning.

  19. Selective laser cleaning of chlorine on ancient coins

    NASA Astrophysics Data System (ADS)

    Aiello, Domenico; Buccolieri, Alessandro; Buccolieri, Giovanni; Castellano, Alfredo; Di Giulio, Massimo; Leo, Laura Sandra; Lorusso, Antonella; Nassisi, Gloria; Nassisi, Vincenzo; Torrisi, Lorenzo

    2007-05-01

    Results about the efficiency of the laser cleaning on the reduction of corrosion products from the surface of ancient coins are reported. In this work an ancient copper coin datable from 1500 to 1600 A.D. and a UV excimer laser were utilized. The goal of this work consists to study the potentiality of UV laser treatment in the reduction of the chlorine concentration on the coin surface which is the main responsible of the corrosion processes of the ancient coins. We used Energy Dispersive X-Ray Fluorescence (EDXRF) and X-Ray Diffraction (XRD) techniques to estimate the chemical composition of the coin surface, before and after UV excimer laser cleaning. In particular, we measured the chlorine, copper and calcium concentrations. We found that a radiation dose of about 19 J/cm2 was able to reduce the chlorine concentration from 2.3 % w/w to 0.6 % w/w without damaging the metal bulk.

  20. Experimental investigation on cleaning of corroded ancient coins using a Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Zhu, Huazhong; Lu, Jian; Ni, Xiaowu; Shen, Zhonghua

    2017-05-01

    The objective of the work reported is to study experimentally on the removal of corrosion layer from the ancient coins using laser beam as the conservation tool. With the use of Q-switched Nd:YAG laser radiation at 1064 nm, dry laser cleaning, steam laser cleaning and chemical-assisted laser cleaning were used to find out a more suitable and efficient laser treatment for corrosion removal. Cleaning tests were performed on ancient Chinese coins. Experimental results shows that the dry laser cleaning was not successful at removing all types of corrosion crust. It was possible to remove the outer thicker layer of the corrosion products (typically known as patina), but failed on the thinner layer of cuprite. The steam laser cleaning could decrease the initial removal threshold and improve the removal efficiency especially for the oxidation with powdery structure. As for chemical-assisted laser treatment, the cleaning results demonstrate that the combination of laser and chemical reagent could provide a considerable improvement in corrosion removal compared with the conventional laser treatments. Most of the corrosion contaminant was stripped, even the cuprite layer. Moreover, no secondary pollution was formed on the cleaned surface. X-ray fluorescence was applied to determine the variation of composition of surface layer and bulk metal before and after the coins cleaned. It shows that all of the three laser treatments were efficient to reduce the chlorine concentration on the surface of the coins more than 75%.

  1. 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.

  2. In situ window cleaning by laser blowoff through optical fiber

    SciTech Connect

    Alfier, A.; Pasqualotto, R.; Barison, S.; Pagura, C.; Danieli, T.; Giudicotti, L.

    2008-10-15

    The feasibility of a window cleaning system based on the laser blowoff technique is investigated to remove the impurity deposition on vacuum windows of the modified reversed field experiment fusion device. The laser pulse is sent to the window through a fused silica fiber optic ({phi}=1 mm), then focused on its internal surface, single shot ablating up to {approx}5 mm{sup 2} of the impurity layer; the focused pulse is scanned across the window to clean its entire surface. The composition of the deposited layer is studied through the secondary ion mass spectrometry and profilometry techniques. Effectiveness of cleaning is analyzed in terms of quality of the cleaned spot, its dimension, repetition rate of the laser, and its wavelength. The energy damage threshold of the fiber optic is also investigated. Three different lasers (microjoule Nd:YAG, Nd:YLF, and ruby) are first tested directly on the window; then only the ruby laser beam is propagated through an optical fiber and tested.

  3. In situ window cleaning by laser blowoff through optical fiber.

    PubMed

    Alfier, A; Barison, S; Danieli, T; Giudicotti, L; Pagura, C; Pasqualotto, R

    2008-10-01

    The feasibility of a window cleaning system based on the laser blowoff technique is investigated to remove the impurity deposition on vacuum windows of the modified reversed field experiment fusion device. The laser pulse is sent to the window through a fused silica fiber optic (phi=1 mm), then focused on its internal surface, single shot ablating up to approximately 5 mm(2) of the impurity layer; the focused pulse is scanned across the window to clean its entire surface. The composition of the deposited layer is studied through the secondary ion mass spectrometry and profilometry techniques. Effectiveness of cleaning is analyzed in terms of quality of the cleaned spot, its dimension, repetition rate of the laser, and its wavelength. The energy damage threshold of the fiber optic is also investigated. Three different lasers (microjoule Nd:YAG, Nd:YLF, and ruby) are first tested directly on the window; then only the ruby laser beam is propagated through an optical fiber and tested.

  4. Ultraviolet-Ozone Cleaning of Semiconductor Surfaces

    DTIC Science & Technology

    1992-10-01

    cleaning; (b) after UV/ozone cleaning. 4 3. Absorption spectrum of oxygen . 7 4. Absorption spectrum of ozone. 7 5. Schematic drawing of a UV/ozone...A clean glass surface was obtained after 15 hours of exposure to the UV radiation in air. In a vacuum system at 104 torr of oxygen , clean gold... oxygen . It took 60 minutes in 20 torr of oxygen , and no cleaning effect was observed in 1 torr after 60 minutes of cleaning (47). (It should be noted

  5. 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.

  6. Ultraviolet-Ozone Cleaning of Semiconductor Surfaces

    DTIC Science & Technology

    1992-01-01

    to the UV radiation in air. In a vacuum system at 10-4 tort of oxygen , clean gold surfaces were produced after about two hours of UV exposure. During...torr of oxygen , and no cleaning effect was observed in 1 torr after 60 minutes of cleaning (46). (It should be noted, however, that the cleaning...source can be used as an "ozone killer." For example, in one cryopumped vacuum system, UV/ozone cleaning was performed in up to 20 torr of oxygen . After

  7. 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.

  8. Cleaning of extremely sensitive optical surfaces

    NASA Astrophysics Data System (ADS)

    Lizon, Jean Louis; Deiries, Sebastian

    2014-07-01

    Most of the optical surfaces are sensitive; the cleaning should be done with great cares and using well characterized technique and equipment. In this paper we are reporting about cleaning of some of the most critical optical surfaces, surfaces which are generally known as not allowing any cleaning. The first section reports about the cleaning of the silver coating on an echelle grating. Silver becomes oxidized, or tarnished, from exposure to sulphates in the air. With time this can lead to dramatic loss of the efficiency of the grating. The second section reports about the cleaning of a CCD chip which has been contaminated with grease. A special "contactless" cleaning procedure has been developed and used successfully on real components. In both cases the full procedure is described and a set of measurements document the results and shows how the original performance have been recovered.

  9. Composition and Method for Cleaning Salt Residues From Metal Surfaces.

    DTIC Science & Technology

    CLEANING, *METALS), (*AIRCRAFT ENGINES, CLEANING), (*PATENTS, CLEANING), ETHYLENEDINITRILO TETRAACETATES, SALTS , HELICOPTER ENGINES...ETHYLENEDIAMINE, SODIUM COMPOUNDS, POLYETHYLENE PLASTICS, PROPENES, SURFACE ACTIVE SUBSTANCES, ACETATES, CORROSION, NITRITES

  10. EM Task 12 -- Laser cleaning of contaminated painted surfaces. Semi-annual report, April 1--September 30, 1997

    SciTech Connect

    Grisanti, A.A.; Jenson, R.R.; Allan, S.E.

    1997-12-31

    Surface decontamination of concrete and steel surfaces in nuclear facilities provides cost savings during decommissioning operations by allowing recycling or reuse of concrete and steel structures. Separation of radionuclides and other contamination from the concrete or steel substrates also allows reduction in volume of hazardous materials during the D and D (decontamination and decommissioning) process, resulting in further cost savings. Several techniques are available or under development for surface decontamination in nuclear facilities. Each technique has its merits; however, none of them is universally the best choice for all surface decontamination applications. Because of the multitude of factors which influence the environmental and economic aspects of selecting a surface decontamination technique, it is difficult to select the best method in a given situation; an objective basis for comparing techniques is needed. The objective of this project is to develop a software tool for use by personnel selecting a surface decontamination technique. The software will incorporate performance data for available surface decontamination techniques. The major activities in the project are broken down as follows: Task 1--Complete decision tree development; Task 2--Literature search for surface decontamination reports; Task 3--Compilation of database from literature data; Task 4--Sensitivity analysis and model design; Task 5--Design of model data structures; and Task 6--PC software design and coding. Work during this reporting period completed Tasks 1, 2, 3, 5, and 6. Task 4 activities resulted in a prototype of the model design; sensitivity analysis and model modifications are in progress at the time of this report. Task 4 will be complete prior to the end of December 1997. A working prototype of the software implementation of the surface decontamination model and technology database has been completed. The program developed at the Energy and Environmental Research

  11. Cleaning of the first mirrors and diagnostic windows by YAG laser on HL-2A

    NASA Astrophysics Data System (ADS)

    Zhou, Y.; Zheng, L.; Gao, H.; Zhao, G.; Li, Y. G.; Li, L. C.; Jiao, Y. M.

    2009-12-01

    A laser cleaning system for HL-2A tokamak first mirrors and diagnostic windows has been developed recently. A detailed description of the laser cleaning procedure is presented. The optical transmission performance measured before and after the laser cleaning of the impurity film deposited on the optical elements is investigated. HL-2A deposited layers on metal mirrors and glass windows with thicknesses of about 1 and 4 μm, respectively, are clearly removed by irradiation with a single pulse of a Q-switched Nd:YAG laser with energy density of 0.4 and 2.8 J cm-2, respectively. The feasibility of cleaning ECE windows is demonstrated. A cleaning time of about 5 min is suitable for application in fusion devices. The comparison of results obtained at different laser wavelengths shows that there is a greater probability of damage to the metallic mirror surface with a short laser wavelength than with longer wavelength.

  12. Laser ablative fluxless soldering (LAFS): 60Sn-40Pb solder wettability tests on laser cleaned OFHC copper substrates

    SciTech Connect

    Peebles, H. C.; Keicher, D. M.; Hosking, F. M.; Hlava, P. F.; Creager, N. A.

    1991-01-01

    OFHC copper substrates, cleaned by laser ablation under argon and helium gas, were tested for solder wettability by 60Sn-40Pb using an area-of-spread method. The wettability of copper surfaces cleaned under both argon and helium gas was found to equal or exceed the wettability obtained on this surface in air using a standard RMA flux. The area of spread on copper substrates cleaned under helium was eight times larger than the area of spread of substrates cleaned under argon. The enhanced spreading observed on the substrates cleaned under helium gas was found to be due to surface roughness. 11 refs., 8 figs., 2 tabs.

  13. Laser plasma shockwave cleaning of SiO 2 particles on gold film

    NASA Astrophysics Data System (ADS)

    Ye, Yayun; Yuan, Xiaodong; Xiang, Xia; Dai, Wei; Chen, Meng; Miao, Xinxiang; Lv, Haibing; Wang, Haijun; Zheng, Wanguo

    2011-04-01

    A Nd:YAG laser (1064 nm) induces optical breakdown of the airborne above the gold-coated K9 glass surface and the created shockwave removes the SiO2 particles contaminated on the gold films. The laser cleaning efficiency has been characterized by optical microscopy, dark field imaging, ultraviolet-visible-near infrared spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and the Image-pro software. The relationships between removal ratio and particle position and laser gap distance have been studied in the case of single pulse laser cleaning. The results show that the 1064 nm laser induced plasma shockwave can effectively remove the SiO2 particles. The removal ratio can reach above 90%. The effects of particle position and laser gap distance on the cleaning efficiency are simulated for the single pulse laser cleaning. The simulated results are consistent with the experimental ones.

  14. Clean Air Markets - Monitoring Surface Water Chemistry

    EPA Pesticide Factsheets

    Learn about how EPA uses Long Term Monitoring (LTM) and Temporily Integrated Monitoring of Ecosystems (TIME) to track the effect of the Clean Air Act Amendments on acidity of surface waters in the eastern U.S.

  15. 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.

  16. Significant OH production under surface cleaning and air cleaning conditions: Impact on indoor air quality.

    PubMed

    Carslaw, N; Fletcher, L; Heard, D; Ingham, T; Walker, H

    2017-11-01

    We report measurements of hydroxyl (OH) and hydroperoxy (HO2 ) radicals made by laser-induced fluorescence spectroscopy in a computer classroom (i) in the absence of indoor activities (ii) during desk cleaning with a limonene-containing cleaner (iii) during operation of a commercially available "air cleaning" device. In the unmanipulated environment, the one-minute averaged OH concentration remained close to or below the limit of detection (6.5×10(5)  molecule cm(-3) ), whilst that of HO2 was 1.3×10(7)  molecule cm(-3) . These concentrations increased to ~4×10(6) and 4×10(8)  molecule cm(-3) , respectively during desk cleaning. During operation of the air cleaning device, OH and HO2 concentrations reached ~2×10(7) and ~6×10(8)  molecule cm(-3) respectively. The potential of these OH concentrations to initiate chemical processing is explored using a detailed chemical model for indoor air (the INDCM). The model can reproduce the measured OH and HO2 concentrations to within 50% and often within a few % and demonstrates that the resulting secondary chemistry varies with the cleaning activity. Whilst terpene reaction products dominate the product composition following surface cleaning, those from aromatics and other VOCs are much more important during the use of the air cleaning device. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  17. Plasma surface cleaning using microwave plasmas

    SciTech Connect

    Tsai, C.C.; Haselton, H.H.; Nelson, W.D.; Schechter, D.E.; Thompson, L.M.; Campbell, V.B.; Glover, A.L.; Googin, J.M.

    1993-11-01

    In a microwave electron cyclotron resonance (ECR) plasma source, reactive plasmas of oxygen and its mixture with argon are used for plasma-cleaning experiments. Aluminum test samples (0.95 {times} 1.9 cm) were coated with thin films ({le} 20 {mu}m in thickness) of Shell Vitrea oil and cleaned by using such reactive plasmas. The plasma cleaning was done in various discharge conditions with fixed microwave power, rf power, biased potential, gas pressures (0.5 and 5 mtorr), and operating time up to 35 min. The status of plasma cleaning has been monitored by using mass spectroscopy. Mass loss of the samples after plasma cleaning was measured to estimate cleaning rates. Measured clean rates of low pressure (0.5 mtorr) argon/oxygen plasmas were as high as 2.7 {mu}/min. X-ray photoelectron spectroscopy was used to determine cleanliness of the sample surfaces and confirm the effectiveness of plasma cleaning in achieving atomic levels of surface cleanliness. In this paper, significant results are reported and discussed.

  18. Degreasing of Solid Surfaces by Microbubble Cleaning

    NASA Astrophysics Data System (ADS)

    Miyamoto, Makoto; Ueyama, Satoshi; Hinomoto, Nobuhide; Saitoh, Tadashi; Maekawa, Shigeki; Hirotsuji, Junji

    2007-03-01

    It is increasingly required to reduce the environmental impact and cost in the field of industrial cleaning. As a substitute for conventional degreasing technology using organic solvents, acids, and alkalis, the authors have developed a new cleaning technology that uses microbubbles having an average diameter of about 70 μm. Grease being adsorbed onto a bubble’s surface and grease being separated from a solid surface by its buoyancy were captured using a high-speed microscopic video camera to demonstrate the degreasing capability of bubbles. High-density microbubbles were generated by adding a trace amount of a specific chemical (0.1% weight or less). The cleaning performance using microbubbles was found to be highly improved compared with that using normal bubbles. It was also revealed that the grease removal efficiency was strongly dependent on the viscosity of the grease. Raising the temperature of the cleaning solution is an effective method of improving cleaning performance by reducing the viscosity. Finally, the degreasing of about 150 machining metal parts at the same time was demonstrated to exceed the common target cleaning level (5-20 μg/cm2) in only 2 min because of their large surface area. Furthermore, the high degreasing performance was maintained even after repeated use of the cleaning solution because of the separation of grease due to buoyancy.

  19. 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.

  20. Laser system for space debris cleaning

    NASA Astrophysics Data System (ADS)

    Rubenchik, A. M.; Erlandson, A. C.; Liedahl, D.

    2012-07-01

    Starting with intensity requirements for producing efficient ablation thrust, then applying orbital mechanics and taking beam transport into account, we have determined the laser pulse energy and the number of pulses required for removing orbital debris. Our calculations show that a ground-based, diode-pumped, gas-cooled multi-slab laser, that uses only modest extensions of existing technology, would be capable of removing most small debris from low-earth orbit, when used with a 3-m-diameter beam director. Such a laser would also be capable of moving large debris into orbits that avoid high-value satellites and of even removing large debris from orbit, by illuminating the debris over several encounters. The laser design we propose uses diode-pumped, Nd:glass, gas-cooled amplifiers with 25-cm square apertures. When operating at the laser fundamental wavelength of 1054 nm, each beamline would produce ˜ 8kJ/4ns pulses at 15 Hz. Two such beamlines, combined using established polarization-combining methods, would be sufficient for orbital debris cleaning. Alternatively, when operating at the second harmonic of 527 nm, each beamline would produce ˜ 7 kJ/4 ns pulses. Due to reduced beam divergence and a smaller beam diameter at the debris, a single harmonically-converted beamline can be useful. We estimate that the first-of-a-kind beamline could be deployed within 4-5 years of project start at a cost of 100-150M. Later beamlines would require less development and engineering costs and would have substantially lower overall cost.

  1. UV/Ozone Cleaning of Surfaces

    DTIC Science & Technology

    1986-05-01

    clean surfaces under UV radiation maintained the surface cleanliness indefinitely. Duting the period 1974-1976, Vig et al.( 3 - 5 ) described a series of...probably no other device of which the performance is so critically dependent upon surface cleanliness . For example, the aging requirement for one 5 MHz...such a device changes the frequency by about one part in 106. The surface cleanliness must therefore be such that the rate of contamination transfer

  2. 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.

  3. 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.

  4. 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.

  5. Multiphysics modelling and simulation of dry laser cleaning of micro-slots with particle contaminants

    NASA Astrophysics Data System (ADS)

    Yue, Liyang; Wang, Zengbo; Li, Lin

    2012-04-01

    Light could interact differently with thin-film contaminants and particle contaminates because of their different surface morphologies. In the case of dry laser cleaning of small transparent particles, it is well known that particles could function like mini-lenses, causing a localized near-field hot spot effect on the cleaning process. This paper looks into a special, yet important, phenomenon of dry laser cleaning of particles trapped in micro-sized slots. The effects of slot size, particle size and particle aggregate states in the cleaning process have been theoretically investigated, based on a coupled electromagnetic-thermal-mechanical multiphysics modelling and simulation approach. The study is important for the development and optimization of laser cleaning processes for contamination removal from cracks and slots.

  6. Laser cleaning of oil spill on coastal rocks

    NASA Astrophysics Data System (ADS)

    Kittiboonanan, Phumipat; Rattanarojpan, Jidapa; Ratanavis, Amarin

    2015-07-01

    In recent years, oil spills have become a significant environmental problem in Thailand. This paper presents a laser treatment for controlled-clean up oil spill from coastal rocks. The cleaning of various types of coastal rocks polluted by the spill was investigated by using a quasi CW diode laser operating at 808 nm. The laser power was attempted from 1 W to 70 W. The result is shown to lead to the laser removal of oil spill, without damaging the underlying rocks. In addition, the cleaning efficiency is evaluated using an optical microscope. This study shows that the laser technology would provide an attractive alternative to current cleaning methods to remove oil spill from coastal rocks.

  7. Improving the laser-induced damage threshold of 532-nm antireflection coating using plasma ion cleaning

    NASA Astrophysics Data System (ADS)

    Zhu, Meiping; Xing, Huanbin; Chai, Yingjie; Yi, Kui; Sun, Jian; Wang, Jianguo; Shao, Jianda

    2017-01-01

    BK7 glass substrates were precleaned by different cleaning procedures before being loaded into a vacuum chamber, and then a series of plasma ion cleaning procedures were conducted at different bias voltages in the vacuum chamber, prior to the deposition of 532-nm antireflection (AR) coatings. The plasma ion cleaning process was implemented by the plasma ion bombardment from an advanced plasma source. The surface morphology of the plasma ion-cleaned substrate, as well as the laser-induced damage threshold (LIDT) of the 532-nm AR coating was investigated. The results indicated that the LIDT of 532-nm AR coating can be greatly influenced by the plasma ion cleaning energy. The plasma ion cleaning with lower energy is an attractive method to improve the LIDT of the 532-nm AR coating, due to the removal of the adsorbed contaminations on the substrate surface, as well as the removal of part of the chemical impurities hidden in the surface layer.

  8. 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.

  9. 40 CFR 761.369 - Pre-cleaning the surface.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 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 mop...

  10. Different regimes of viscous melt flow in laser ablation: From "clean" ablation to nanostructuring

    NASA Astrophysics Data System (ADS)

    Tokarev, Vladimir N.; Lazare, Sylvain; Kaplan, Alexander F. H.

    2006-05-01

    The paper reviews recent results on modeling a viscous liquid flow driven by ablation pressure. Based on the analysis of the Navier-Stokes equation various strongly different manifestations of this phenomenon are explained. These are: (i) a "clean" laser ablation, when laser spot has a clean sharp spot border, free from a re-solidified melt dross; (ii) a new form of material removal in laser ablation - expulsion on a poly(methyl methacrylate) target of long (up to 1 mm) nanofibers with a radius about 150-200 nm to the exterior of the spot under the action of a single pulse of KrF excimer laser; and (iii) a new way of laser surface nanostructuring - the formation of a surface foam having a structure of micro-pores interconnected with nanofilaments of diameters about 100 nm as a result of single pulse KrF laser irradiation of biopolymer films.

  11. Laser Surface Treatment

    NASA Astrophysics Data System (ADS)

    Gnanamuthu, D. S.

    1980-10-01

    Experimental procedures and current state-of-the-art are presented for laser surface treating methods such as alloying, cladding, grain refining, and transformation hardening using a cw CO2 laser. Microstructural and x-ray analyses of the treated surfaces indicate that a laser beam can locally enhance surface properties. Laser alloying offers the possibility to selectively modify a low cost workpiece surface so that it has the desired high quality surface properties characteristic of high performance alloys. Laser cladding offers feasibility to apply high melting cladding alloys on low melting workpieces, to reduce the amount of dilution of cladding alloy with the workpieces, and the potential to apply dense ceramic claddings to metallic workpieces. Laser grain refining offers potential to either minimize or eliminate surface defects such as inclusions, intermetallic compounds, and pores, and to provide a refined grain structure. Laser transformation hardening provides the treated workpieces with a hard martensitic surface that has compressive stresses for enhanced fatigue life; in addition, reduction in wear rate of treated surfaces is achieved. This experimental study indicates that the use of lasers for surface treatment has several limitations. Further studies will provide better understanding for maximum utilization of laser surface treating processes.

  12. 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.

  13. Laser cleaning: an alternative method for removing oil-spill fuel residues

    NASA Astrophysics Data System (ADS)

    Mateo, M. P.; Nicolas, G.; Piñon, V.; Ramil, A.; Yañez, A.

    2005-07-01

    Cleaning methods employed in last oil spills usually require direct contact or the intervention of external agents that can lead to additional contamination and damage of treated surfaces. As an alternative, a laser-based methodology is proposed in this work for controlled removal of fuel residues caused by the accident of Prestige tanker from rocks, as well as tools and equipment employed in fuel retaining and elimination procedures. Ablation thresholds of fuel crust and underlying material have been investigated with the aim to establish operational parameters that preserve the structural integrity and identity of the latter. The clean-up process was controlled by the self-limiting nature of the process or by laser-induced plasma spectroscopy. Contaminated, no contaminated and cleaned areas of the samples have been characterized by complementary microscopy techniques to help in the task of optimizing the laser cleaning procedure and checking the effectiveness of the removal process.

  14. Suppression of melt flows in laser ablation: application to clean laser processing

    NASA Astrophysics Data System (ADS)

    Tokarev, Vladimir N.; Kaplan, Alexander F. H.

    1999-07-01

    It is shown that in laser ablation of materials with large Prandtl numbers (mainly ceramics and polymers) a motion of the melt along the surface caused by the vapour plume pressure is essentially retarded for thin enough melt layers due to the onset of viscous friction. For polymers in nanosecond laser ablation this melt displacement can be obtained to be less than the ablation depth per pulse (which is typically 0.2-1 µm for nanosecond irradiation), when the absorption coefficient, icons/Journals/Common/alpha" ALT="alpha" ALIGN="TOP"/>, and the kinematic viscosity, icons/Journals/Common/nu" ALT="nu" ALIGN="TOP"/>, satisfy the condition icons/Journals/Common/alpha" ALT="alpha" ALIGN="TOP"/>2icons/Journals/Common/nu" ALT="nu" ALIGN="TOP"/>>108 s-1. Thus, clean precise laser ablation for such polymers can be explained simply in terms of the thermal mechanism, without invoking the concept of photochemical decomposition, in terms of absorption coefficient, melt viscosity and pressure of the ablation plume on the irradiated surface. From this point of view, several factors facilitating clean laser ablation in multipulse irradiation are discussed. However, for metals (usually having a very small Prandtl number) the viscous friction has no significant effect on the retardation lateral melt flow to the periphery. The quality of the laser spot border can still be improved by using laser pulses shorter than 1 ps. In this case, in a shallow spot, the alternative (explosive) melt expulsion mechanism becomes predominant, producing material removal mainly transverse to the spot surface. Thus, the lateral (along the surface) component of melt expulsion appears to be strongly suppressed, having no chance to spoil the border of the spot.

  15. 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.

  16. Laser Cleaning the Abergavenny Hoard: Silver Coins from the Time of William the Conqueror

    NASA Astrophysics Data System (ADS)

    Davis, M.

    The Abergavenny Hoard is a recently discovered collection of late Saxon and Norman silver coins, the details of which were badly obscured by corrosion products and iron concretions. A Q-switched Nd:YAG laser, using near infrared radiation at 1,064 nm, was employed to clean the hoard. Detail retained on the surface of the coins after laser cleaning included "rough-out" marks and polishing marks from the original die, as well as the legend. From this evidence surface damage appears to have been minimal, and the treatment very successful.

  17. 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.

  18. The Potential Use of Laser Ablation for Selective Cleaning of Indiana Limestone

    NASA Astrophysics Data System (ADS)

    Normandin, K. C.; Powers, L.; Slaton, D.; Scheffler, M. J.

    The aim of this investigation and conservation study was to examine and evaluate the laser ablation method as a practical technique for cleaning of Indiana limestone, a calcite-cemented stone widely used in historic structures throughout the United States. To this goal, a thorough petrographic characterization of the samples was performed prior to and following laser cleaning tests by Q-switched and short free running Nd:YAG lasers. The main optimization problem was the amber-gray appearance associated with the laser ablation by Q-switching lasers. Following the evaluation of such a cleaning result, two practicable solutions based on suitable pulse duration or wavelength selections were successfully demonstrated and then compared with different intervention protocols proposed. This chapter will show that through this case study, an understanding of effective uses of cleaning highly weathered Indiana limestone through the use of three types of Q-switched and short free running Nd:YAG lasers can be most effective in the removal from limestone of surface soiling and thick built-up carbon deposits ranging from 0.5 to 1mm in thickness. Case study evaluation methods included petrographic examination of composition, texture, and microstructure using optical microscopy and scanning electron microscopy performed on thin and polished sections of limestone sampled from six areas before and after cleaning. The microscopy studies were supplemented with energy-dispersive X-ray spectroscopy to characterize crystalline phases and track changes in chemistry.

  19. 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.

  20. 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.

  1. Surface treatments by laser

    NASA Astrophysics Data System (ADS)

    Thomann, A. L.; Benzerga, R.; Basillais, Armelle; Georges, Cecile; Fariaut, Francois; Semmar, Nadjib; Boulmer-Leborgne, Chantal

    2003-07-01

    Laser treatments of various metals are studying depending on the laser wavelength, pulse time duration and shape, and fluence (laser/metal interaction regime). Low fluence excimer UV laser melting process of gold layer is shown to improve the corrosion resistance of multilayer (Au/Ni/Cu alloy) electrical contacts. For this application the homogenity of the laser beam as well as the initial Cu substrate roughness are found to be limiting parameters of the process. Carburization of Al alloy, performed in C3H6 atmosphere with a KrF laser induces the incorporation of carbon atoms over about 4 μm depth. The crystalline Al4C3 synthesized at the surface leads to a strengthening of the light Al alloy, which is of great interest for application in car industry. The study shows that diffusion of C atom in the target is possible because of a plasma presence on the surface which supports the molten bath life time and induces dissociation of the ambient gas. In the last example of laser metal surface treatment presented in that paper, a commonly used steel is treated in air with different lasers at a fluence above the plasma formation threshold. It is seen that the machining oils covering the surface before the treatment can be efficiently removed and that new compounds (nitride, carbide and oxides) are formed at the surface.

  2. 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

  3. 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.

  4. Treating the untreatable in art and heritage materials: ultrafast laser cleaning of "cloth-of-gold".

    PubMed

    Kono, Mitsuhiko; Baldwin, Kenneth G H; Wain, Alison; Rode, Andrei V

    2015-02-03

    Laser cleaning provides art and heritage conservators with an alternative means to restore objects when traditional chemical and mechanical methods are not viable. However, long (>nanosecond) laser pulses can cause unwanted damage from photothermal processes and provide limited control over ablation depth. Ultrashort (lasers are emerging as a more appropriate tool for cleaning historic artifacts because of their unique ability to avoid heat- and shock-wave generation, thus minimizing collateral damage of the underlayers, and to remove material with near-nanometer precision. Here we demonstrate the effectiveness of ultrashort pulses by cleaning 19th century military gold braid without any detrimental effects on the gold foil or the underlying silk thread structure. The results are compared with nanosecond-pulse laser treatment that damages the surface structure. By introducing in situ feedback control of the laser ablation via laser-induced breakdown spectroscopy (LIBS) monitoring of the ablated plume, we are able to halt the cleaning process just as the contaminant layer is completely removed. This technique allows ultrafast laser ablation to extend the armory of conservation treatments, enabling restoration of a range of complex and fragile heritage objects previously untreatable by conventional means.

  5. 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.

  6. 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.

  7. Practical issues in laser cleaning of stone and painted artefacts: optimisation procedures and side effects

    NASA Astrophysics Data System (ADS)

    Pouli, Paraskevi; Oujja, Mohamed; Castillejo, Marta

    2012-02-01

    In the last twenty years lasers have acquired an important role in the study and the preservation of Cultural Heritage (CH) objects and Monuments, as they have effectively illuminated a number of complex diagnostic and restoration problems. Their unique properties have enabled their use in a wide range of conservation applications, since they ensure interventions with precise control, material selectivity and immediate feedback. Surface cleaning, based on laser ablation, is a delicate, critical and irreversible process, which, given the multitude of materials that may be present on a CH object and the often fragile or precarious condition of the original surfaces, is fraught with many potential complications. Therefore it is crucial to choose the best possible laser cleaning methodology for each individual case, which involves optimising the laser parameters according to material properties, as well as the thorough knowledge of the ablation mechanisms involved. In this context the systematic investigation and elucidation of potential damage or side effects occurring upon cleaning is essential, as it delineates the possibilities and limitations of laser ablation and allows the fine-tuning of the operating parameters for a successful cleaning intervention. This paper is an overview of studies investigating the mechanisms which are responsible for the laser-induced discoloration effects. Emphasis is given on the yellowing coloration observed on stonework upon infrared (IR) ablation of pollution encrustations, while the various theories introduced to approach the different physical and/or chemical processes and mechanisms responsible for such side effects are discussed. In this respect the different laser cleaning methodologies, which are based on the use of laser systems with different pulse durations and wavelength characteristics, introduced in order to rectify or prevent discoloration on stonework are presented. In parallel, the darkening phenomena which occur upon

  8. Self-Cleaning Properties on Superhydrophobic Surfaces via Condensation

    NASA Astrophysics Data System (ADS)

    Miller, David; Crockett, Julie; Maynes, Daniel

    2016-11-01

    Superhydrophobic (SH) surfaces have many unique capabilities, one of which is self-cleaning. When a water droplet rolls on a contaminated SH surface, particulates can adhere to the droplet and roll away with the droplet, creating a self-cleaning effect. Another unique characteristic of SH surfaces is the promotion of dropwise condensation when cooled in a humid environment. These droplets may engulf particulates on the surface as they are generated and coalesce. This research seeks to understand the potential cleaning efficiency SH surfaces have when water vapor is condensed on a dirty SH surface and allowed to roll off. Multiple condensation cycles with common particulates deposited on SH surfaces oriented vertically are explored. Sliding and contact angles are measured to approximate the cleaning efficiency of the condensed, rolling droplets after each condensation cycle. Results are compared with the cleaning efficiency of water droplets placed on the surface to roll. Moxtek, INC.

  9. 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.

  10. 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.

  11. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Effect of pulsed laser target cleaning on ionisation and acceleration of ions in a plasma produced by a femtosecond laser pulse

    NASA Astrophysics Data System (ADS)

    Volkov, Roman V.; Vorobiev, A. A.; Gordienko, Vyacheslav M.; Dzhidzhoev, M. S.; Lachko, I. M.; Mar'in, B. V.; Savel'ev, Andrei B.; Uryupina, D. S.

    2005-10-01

    The impurity layer on the surface of a solid target is shown to exert a significant effect on the characteristics of the ion current of the laser plasma produced under the action of ultrahigh-intensity femtosecond radiation on the surface of this target. The application of pulsed laser cleaning gives rise to an additional high-energy component in the ion spectrum of the target material. It is shown that the ion current parameters of the laser plasma such as the average and highest ion charge, the highest ion energy of the target material, etc., can be controlled by varying the lead time of the cleaning laser radiation.

  12. 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.

  13. In situ cleaning of diagnostic first mirrors: an experimental comparison between plasma and laser cleaning in ITER-relevant conditions

    NASA Astrophysics Data System (ADS)

    Maffini, A.; Moser, L.; Marot, L.; Steiner, R.; Dellasega, D.; Uccello, A.; Meyer, E.; Passoni, M.

    2017-04-01

    This paper presents an experimental comparison between the plasma cleaning and the laser cleaning techniques of diagnostic first mirrors (FMs). The re-deposition of contaminants sputtered from a tokamak first wall onto FMs could dramatically decrease their reflectance in an unacceptable way for the proper functioning of plasma diagnostic systems. Therefore, suitable in situ cleaning solutions will be required to recover the FMs reflectance in ITER. Currently, plasma cleaning and laser cleaning are considered the most promising solutions. In this work, a set of ITER-like rhodium mirrors contaminated with materials tailored to reproduce tokamak redeposits is employed to experimentally compare plasma and laser cleaning against different criteria (reflectance recovery, mirror integrity, time requirement). We show that the two techniques present different complementary features that can be exploited for the cleaning of ITER FMs. In particular, plasma cleaning ensures an excellent reflectance recovery in the case of compact contaminants, while laser cleaning is faster, gentler, and more effective in the case of porous contaminant. In addition, we demonstrate the potential benefits of a synergistic solution which combines plasma and laser cleaning to exploit the best features of each technique.

  14. Evaluating the use of laser radiation in cleaning of copper embroidery threads on archaeological Egyptian textiles

    NASA Astrophysics Data System (ADS)

    Abdel-Kareem, Omar; Harith, M. A.

    2008-07-01

    Cleaning of copper embroidery threads on archaeological textiles is still a complicated conservation process, as most textile conservators believe that the advantages of using traditional cleaning techniques are less than their disadvantages. In this study, the uses of laser cleaning method and two modified recipes of wet cleaning methods were evaluated for cleaning of the corroded archaeological Egyptian copper embroidery threads on an archaeological Egyptian textile fabric. Some corroded copper thread samples were cleaned using modified recipes of wet cleaning method; other corroded copper thread samples were cleaned with Q-switched Nd:YAG laser radiation of wavelength 532 nm. All tested metal thread samples before and after cleaning were investigated using a light microscope and a scanning electron microscope with an energy dispersive X-ray analysis unit. Also the laser-induced breakdown spectroscopy (LIBS) technique was used for the elemental analysis of laser-cleaned samples to follow up the laser cleaning procedure. The results show that laser cleaning is the most effective method among all tested methods in the cleaning of corroded copper threads. It can be used safely in removing the corrosion products without any damage to both metal strips and fibrous core. The tested laser cleaning technique has solved the problems caused by other traditional cleaning techniques that are commonly used in the cleaning of metal threads on museum textiles.

  15. 40 CFR 761.369 - Pre-cleaning the surface.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Pre-cleaning the surface. 761.369 Section 761.369 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES... PROHIBITIONS Double Wash/Rinse Method for Decontaminating Non-Porous Surfaces § 761.369 Pre-cleaning...

  16. 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 Section 761.369 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES... PROHIBITIONS Double Wash/Rinse Method for Decontaminating Non-Porous Surfaces § 761.369 Pre-cleaning...

  17. Effect of different provisional cement remnant cleaning procedures including Er:YAG laser on shear bond strength of ceramics

    PubMed Central

    Zortuk, Mustafa; Gumus, Hasan Onder; Kilinc, Halil Ibrahim

    2012-01-01

    PURPOSE The purpose of this study was to evaluate the effect of provisional cement removal by different dentin cleaning protocols (dental explorer, pumice, cleaning bur, Er:YAG laser) on the shear bond strength between ceramic and dentin. MATERIALS AND METHODS In total, 36 caries-free unrestored human third molars were selected as tooth specimens. Provisional restorations were fabricated and cemented with eugenol-free provisional cement. Then, disc-shaped ceramic specimens were fabricated and randomly assigned to four groups of dentin cleaning protocols (n = 9). Group 1 (control): Provisional cements were mechanically removed with a dental explorer. Group 2: The dentin surfaces were treated with a cleaning brush with pumice Group 3: The dentin surfaces were treated with a cleaning bur. Group 4: The provisional cements were removed by an Er:YAG laser. Self-adhesive luting cement was used to bond ceramic discs to dentin surfaces. Shear bond strength (SBS) was measured using a universal testing machine at a 0.05 mm/min crosshead speed. The data were analyzed using a Kolmogorov Smirnov, One-way ANOVA and Tukey HSD tests to perform multiple comparisons (α=0.05). RESULTS The dentin cleaning methods did not significantly affect the SBS of ceramic discs to dentin as follows: dental explorer, pumice, cleaning bur, and Er:YAG laser. CONCLUSION The use of different cleaning protocols did not affect the SBS between dentin and ceramic surfaces. PMID:23236570

  18. Laser nitriding and laser carburizing of surfaces

    NASA Astrophysics Data System (ADS)

    Schaaf, Peter

    2003-11-01

    Laser irradiation of surfaces with short pulses in reactive atmospheres (nitrogen, methane) can lead to very effective nitrification and carburization via complicated laser-surface-gas-plasma-interactions. This laser nitriding and laser carburizing and their basic underlying phenomena will be presented and partly explained by results of example materials (iron, titanium, aluminum, silicon) where nitride and carbide coatings can be formed by fast and easily by Excimer Laser, Nd:YAG laser, Free Electron Laser and also by femtosecond Ti:sapphire laser. This implies laser pulse durations from the nanosecond to the femtosecond regime and wavelengths from ultra-violet to infrared. The resulting surfaces, thin films, coatings and their properties are investigated by combining Mossbauer Spectroscopy, x-ray diffraction, x-ray absorption spectroscopy, Nanoindentation, Resonant Nuclear Reaction Analysis, and Rutherford Backscattering Spectroscopy.

  19. Investigation of aluminum surface cleaning using cavitating fluid flow

    SciTech Connect

    Ralys, Aurimas; Striška, Vytautas; Mokšin, Vadim

    2013-12-16

    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.

  20. 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.

  1. Comparative study of ornamental granite cleaning using femtosecond and nanosecond pulsed lasers

    NASA Astrophysics Data System (ADS)

    Rivas, T.; Lopez, A. J.; Ramil, A.; Pozo, S.; Fiorucci, M. P.; Silanes, M. E. López de; García, A.; Aldana, J. R. Vazquez de; Romero, C.; Moreno, P.

    2013-08-01

    Granite has been widely used as a structural and ornamental element in public works and buildings. In damp climates it is almost permanently humid and its exterior surfaces are consequently biologically colonized and blackened We describe a comparative analysis of the performance of two different laser sources in removing biological crusts from granite surfaces: nanosecond Nd:YVO4 laser (355 nm) and femtosecond Ti:Sapphire laser at its fundamental wavelength (790 nm) and second harmonic (395 nm). The granite surface was analyzed using scanning electron microscopy, attenuated total reflection - Fourier transform infrared spectroscopy and profilometry, in order to assess the degree of cleaning and to characterize possible morphological and chemical changes caused by the laser sources.

  2. 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.

  3. 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.

  4. Ge(001) surface cleaning methods for device integration

    NASA Astrophysics Data System (ADS)

    Ponath, P.; Posadas, A. B.; Demkov, A. A.

    2017-06-01

    In recent years, research on Ge nanodevices has experienced a renaissance, as Ge is being considered a possible high mobility channel material replacement for Si MOSFET devices. However, for reliable high performance devices, an atomically flat and perfectly clean Ge surface is of utmost importance. In this review, the existing methods for cleaning the Ge(001) surface are reviewed and compared for the first time. The review discusses three broad categories of cleaning techniques that have been successfully demonstrated to obtain a clean Ge surface. First, the use of ultraviolet light and/or oxygen plasma is discussed. Both techniques remove carbon contamination from the Ge surface and simultaneously form an oxide passivation layer. Second, in situ ion sputtering in combination with germanium regrowth, which can lead to extremely clean and well-ordered Ge surfaces, is discussed. Finally, various wet-etching recipes are summarized, with focus on hydrofluoric acid (HF), NH4OH, and HCl. Despite the success of HF for Si surface preparation, it is demonstrated that in the case of Ge, HF is outperformed by other chemicals with respect to surface roughness, carbon and oxide removal efficiency. It is shown that several cleaning methods can lead to a perfectly clean Ge surface, but only a few methods can be considered for actual device integration due to their effectiveness, simplicity, and scaling ability.

  5. 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.

  6. ``Clean'' processing of polymers and smoothing of ceramics by pulsed laser melting

    NASA Astrophysics Data System (ADS)

    Tokarev, V. N.; Marine, W.; Prat, C.; Sentis, M.

    1995-05-01

    Surface stability during laser pulsed melting of polymers and ceramics is studied theoretically. Irradiation conditions and material parameters are found giving rise to the suppression of surface wavy relief of a nonresonant type (with period Λ≫λ, where λ is the radiation wavelength) and thus to the smooth flat irradiation spots. For example, for the polymers considered this process takes place for wavelengths where the absorption coefficient is sufficiently high: α(λ)≳105 cm-1. Thus, it is shown that the formation of such spots, previously referred to as ``clean ablation,'' can be explained using only a thermal mechanism without reference to the concept of ``photodecomposition.'' Moreover, laser smoothing and polishing of a surface, if it had roughness before irradiation, can be achieved by appropriate matching of the characteristic size of this roughness along the surface with the values of α(λ) and laser fluence. Methods are proposed to decrease the parasitic influence of droplets on the deposition of thin films by laser ablation of massive ceramic pellets. The results of theoretical modeling are shown to be in good agreement with experiments on smoothing of rough alumina ceramics and ``clean'' processing of polymers by excimer laser radiation.

  7. On the target surface cleanness during magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Schelfhout, R.; Strijckmans, K.; Boydens, F.; Depla, D.

    2015-11-01

    The thickness of the chemisorbed oxide layer on a tantalum target surface was determined from sputter cleaning experiments. These measurements show a clear logarithmic growth behaviour as a function of the oxygen exposure. By extrapolating this result towards other sputter conditions, the target cleanness during magnetron sputter deposition can be estimated.

  8. 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.

  9. 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.

  10. 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.

  11. Laser cleaning of historical limestone buildings in Bordeaux appraisal using cathodoluminescence and electron paramagnetic resonance.

    PubMed

    Chapoulie, Rémy; Cazenave, Sandrine; Duttine, Mathieu

    2008-05-01

    Most historical buildings in Bordeaux city are made of limestone. This yellowish-white rock is rather porous and highly sensitive to pollution. As a consequence of local weathering conditions, these buildings present a dark appearance due to the development of a superficial dark grey to black crust. For the last decade, a campaign has been underway to clean these buildings. Eleven techniques of surface treatment have been used, including laser beam technology. As a contribution to the study of laser beam effects on stone buildings, two analytical methods have been used on clean versus unclean surfaces: Cathodoluminescence (CL) and Electron Paramagnetic Resonance (EPR), in addition to SEM-EDX and XRD. The black crust is composed of different types of particles: carbon porous micro-particles of industrial origin, atmospheric dust due to the erosion of soils and rocks, alumino-silicate particles from urban pollution; all these particles being cemented by gypsum. As far as heritage conservation is concerned, the laser surface treatment not only preserves the original patina of the stone, but also leaves surface smoothness unaltered. CL and EPR data confirm that lasers--with highly controlled parameters--only get rid of the black crust and, thus, reveal the underneath layer, the so-called patina. This patina shows no luminescence, whereas the limestone on which it has grown shows a bright orange emission of CL. This indicates CL to be a fast and easy way to provide a high quality control for the restoration of polluted ancient stones.

  12. Cleaning, disinfection and sterilization of surface prion contamination.

    PubMed

    McDonnell, G; Dehen, C; Perrin, A; Thomas, V; Igel-Egalon, A; Burke, P A; Deslys, J P; Comoy, E

    2013-12-01

    Prion contamination is a risk during device reprocessing, being difficult to remove and inactivate. Little is known of the combined effects of cleaning, disinfection and sterilization during a typical reprocessing cycle in clinical practice. To investigate the combination of cleaning, disinfection and/or sterilization on reducing the risk of surface prion contamination. In vivo test methods were used to study the impact of cleaning alone and cleaning combined with thermal disinfection and high- or low-temperature sterilization processes. A standardized test method, based on contamination of stainless steel wires with high titres of scrapie-infected brain homogenates, was used to determine infectivity reduction. Traditional chemical methods of surface decontamination against prions were confirmed to be effective, but extended steam sterilization was more variable. Steam sterilization alone reduced the risk of prion contamination under normal or extended exposure conditions, but did show significant variation. Thermal disinfection had no impact in these studies. Cleaning with certain defined formulations in combination with steam sterilization can be an effective prion decontamination process, in particular with alkaline formulations. Low-temperature, gaseous hydrogen peroxide sterilization was also confirmed to reduce infectivity in the presence and absence of cleaning. Prion decontamination is affected by the full reprocessing cycle used on contaminated surfaces. The correct use of defined cleaning, disinfection and sterilization methods as tested in this report in the scrapie infectivity assay can provide a standard precaution against prion contamination. Copyright © 2013 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

  13. Cleaning Historical Metals: Performance of Laser Technology in Monument Preservation

    NASA Astrophysics Data System (ADS)

    Gervais, A.; Meier, M.; Mottner, P.; Wiedemann, G.; Conrad, W.; Haber, G.

    In practical restoration - depending on the object in question and the regional attitude to monument restoration - widely differing techniques and restoration philosophies have been, and still are, applied to the exposure of metal. Depending on the type of metal, this results in differing working materials as well as highly diverging definitions of the required degree of exposure as far as removing corrosive deposits is concerned. Therefore, particularly where metallic or heat sensitive cultural assets are concerned, the applicability of an efficient cleaning procedure using contact-free laser beam technology, which is also gentle on the material, should be examined.

  14. Cu Nanowires with Clean Surfaces: Synthesis and Enhanced Electrocatalytic Activity.

    PubMed

    Liu, Xinmei; Sui, Yongming; Yang, Xinyi; Wei, Yingjin; Zou, Bo

    2016-10-12

    Low activity and high cost of electrocatalysts are the major challenge for the commercialization of the direct fuel cells (DFCs) and biofuel cells. In this work, we demonstrate the desirable "clean surfaces" effect of Cu nanocrystals in electrocatalysis. By a new reaction route of Cu2O nanospheres (Cu2O NSs), Cu nanowires (Cu NWs) with high purity and "clean surfaces" are first obtained under mild conditions. Benefiting from the path directing effects and abundant (100) facets, the as-prepared Cu NWs exhibit a lower overpotential to achieve the methanol electro-oxidation reaction (MOR) than that of analogous Cu nanoparticles (Cu NPs). Moreover, the "clean surfaces" provide more available active sites for the efficient transfer of electrons, enabling the Cu NWs to show their enhanced electrocatalytic activity. In the MOR, forward peak current density for the surface-cleaned Cu NWs is 2839 μA cm(-2), which is ca. 6.45-fold higher than that of the Cu NWs with residual capping molecules on their surface. The "clean surfaces" effect can also be extended to the glucose electro-oxidation reaction (GOR), and the enhancement in specific surface area activity for the Cu NWs is 11.3-fold. This work enhances the electrocatalytic performance of Cu nanocrystals without the need for additional noble metals, which opens up new avenues for utilizing non-noble metals in the DFC or biofuel cell applications.

  15. Critical evaluation of current cleaning protocols for foraminiferal trace metal analyses using single shell Laser-Ablation -ICP measurements

    NASA Astrophysics Data System (ADS)

    Sadekov, A.; Eggins, S. M.; Misra, S.; Kerr, J.; Greaves, M.; Elderfield, H.

    2012-12-01

    Trace element compositions of foraminiferal calcite have been widely used as proxies for past ocean conditions. However, it has been shown that the presence of detrital material, particulate organic matter and diagenically-precipitated overgrowth on test surfaces significantly limit the accuracy of trace element analyses. A number of cleaning methods had been proposed to remove impurities from foraminiferal calcite but their relative effectiveness for foraminiferal trace metal analyses is still debatable. In this work, we employed the microanalytical technique Laser Ablation ICP-MS to compare the most commonly-used cleaning protocols. Distribution of Ca, Mg, Mn, Zn, Ba, Sr, Li, B, Fe, Al across tests of Orbulina universa from modern and Holocene sediments were analysed before and after each cleaning step. The use of Laser Ablation ICP-MS provides accurate and direct comparison of the effectiveness of each cleaning protocol, which was applied to fragments of a single foraminifera test. We also present results obtained using a novel automated cleaning device, "fOraccle", for cleaning single shell and bulk foraminiferal samples. This instrument minimises manual handling of chemical reagents during cleaning, thereby improving reproducibility of the Me/Ca measurements. Based on these results, we will discuss the composition of surface contamination on foraminiferal tests as well as possible ways to improve current cleaning protocols.

  16. Enamel Surface Roughness after Debonding of Orthodontic Brackets and Various Clean-Up Techniques

    PubMed Central

    Ahrari, Farzaneh; Akbari, Majid; Akbari, Javad; Dabiri, Ghahraman

    2013-01-01

    Objective: This study aimed to evaluate enamel roughness after adhesive removal using different burs and an Er:YAG laser. Materials and Methods: The buccal surfaces of forty human premolars were sealed by two layers of nail varnish, except for a circular area of 3 mm in diameter on the middle third. The enamel surfaces were initially subjected to profilometry analysis and four parameters of surface irregularity (Ra, Rq, Rt and Rz) were recorded. Following bracket bonding and debonding, adhesive remnants were removed by tungsten carbide burs in low- or high- speed handpieces (group 1 and 2, respectively), an ultrafine diamond bur (group 3) or an Er:YAG laser (250 mJ, long pulse, 4 Hz) (group 4), and surface roughness parameters were measured again. Then, the buccal surfaces were polished and the third profilometry measurements were performed. Results: The specimens that were cleaned with a low speed tungsten carbide bur showed no significant difference in surface irregularity between the different treatment stages (p>0.05). Surface roughness increased significantly after clean-up with the diamond bur and the Er:YAG laser (p<0.01). In comparison between groups, adhesive removal with tungsten carbide burs at slow- or high-speed handpieces produced the lowest, while enamel clean-up with the Er:YAG laser caused the highest values of roughness measurements (P<0.05). Conclusion: Under the study conditions, application of the ultrafine diamond bur or the Er:YAG laser caused irreversible enamel damage on tooth surface, and thus these methods could not be recommended for removing adhesive remnants after debonding of orthodontic brackets. PMID:23724206

  17. IV INTERNATIONAL CONFERENCE ON ATOM AND MOLECULAR PULSED LASERS (AMPL'99): Surface oxide removal by a XeCl laser for decontamination

    NASA Astrophysics Data System (ADS)

    Sentis, M. L.; Delaporte, Ph; Marine, W.; Uteza, O.

    2000-06-01

    The laser ablation performed with an automated excimer XeCl laser unit is used for large surface cleaning. The study focuses on metal surfaces that are oxidised and are representative of contaminated surfaces with radionuclides in a context of nuclear power plant maintenance. The unit contains an XeCl laser, the beam delivery system, the particle collection cell, and the system for real-time control of cleaning processes. The interaction of laser radiation with a surface is considered, in particular, the surface damage caused by cleaning radiation. The beam delivery system consists of an optical fibre bundle of 5 m long and allows delivering 150 W at 308 nm for laser surface cleaning. The cleaning process is controlled by analysing in real time the plasma electric field evolution. The system permits the cleaning of 2 to 6 m2 h-1 of oxides with only slight substrate modifications.

  18. Laser Cleaning of Undyed Silk: Indications of Chemical Change

    NASA Astrophysics Data System (ADS)

    von Lerber, K.; Strlic, M.; Kolar, J.; Krüger, J.; Pentzien, S.; Kennedy, C.; Wess, T.; Sokhan, M.; Kautek, Wolfgang

    Three different undyed, unweighed silk fabrics (new clean, new soiled, and naturally aged) were cleaned with a computer-controlled Q-switched Nd:YAG laser at 532nm in 30 combinations of fluence and pulse numbers. They were studied for chemical change by viscometry, X-ray diffraction, and FIB-SIMS in combination with temperature calculations. While physical changes only occurred above the tested parameters, chemical changes could be detected as low as 0.2 J cm?2 with four pulses. Yellowing was observed at lower and bleaching at higher fluence/pulse number combinations. Melting was observed in naturally aged silk cleaned with 64 pulses at 4.2 J cm?2. The temperature reached at 0.1 J cm?2 is sufficient to evaporate carbon. Excess energy is transferred into the silk substrate causing thermal degradation. Different chemical processes leading to chain scission and to crosslinking seem to occur simultaneously, even at low fluence and pulse number. An increase in pulse numbers also leads to increasing damage.

  19. 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.

  20. Viscous liquid expulsion in nanosecond UV laser ablation: From ``clean'' ablation to nanostructures

    NASA Astrophysics Data System (ADS)

    Tokarev, V. N.

    2006-09-01

    This paper reviews recent results on modeling UV nanosecond laser ablation. Particular attention is given to a viscous liquid flow driven by ablation pressure. Based on the analysis of the Navier-Stokes equation, various strongly different manifestations of this phenomenon are explained. These are (i) a “clean” laser ablation, when the laser spot has a clean sharp spot border free of resolidified melt dross; (ii) a new form of material removal in laser ablation, expulsion on a poly(methyl methacrylate) target of long (up to 1 mm) nanofibers with a radius about 150-200 nm to the exterior of the spot under the action of a single pulse of a KrF excimer laser; and (iii) a new method of laser surface nanostructuring, the formation of a surface foam having a structure of micropores interconnected by nanofilaments with diameters of about 100 nm as a result of single-pulse KrF laser ablation of biopolymer films.

  1. 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.

  2. 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.

  3. Hierarchical surfaces for enhanced self-cleaning applications

    NASA Astrophysics Data System (ADS)

    Fernández, Ariadna; Francone, Achille; Thamdrup, Lasse H.; Johansson, Alicia; Bilenberg, Brian; Nielsen, Theodor; Guttmann, Markus; Sotomayor Torres, Clivia M.; Kehagias, Nikolaos

    2017-04-01

    In this study we present a flexible and adaptable fabrication method to create complex hierarchical structures over inherently hydrophobic resist materials. We have tested these surfaces for their superhydrophobic behaviour and successfully verified their self-cleaning properties. The followed approach allow us to design and produce superhydrophobic surfaces in a reproducible manner. We have analysed different combination of hierarchical micro-nanostructures for their application to self-cleaning surfaces. A static contact angle value of 170° with a hysteresis of 4° was achieved without the need of any additional chemical treatment on the fabricated hierarchical structures. Dynamic effects were analysed on these surfaces, obtaining a remarkable self-cleaning effect as well as a good robustness over impacting droplets.

  4. 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

  5. Rapid screening of surfactant and biosurfactant surface cleaning performance.

    PubMed

    Onaizi, Sagheer A; He, Lizhong; Middelberg, Anton P J

    2009-08-01

    Surface Plasmon Resonance (SPR) and rubisco protein stain were used as tools to screen the effectiveness of detergent formulations in cleaning a protein stain from solid surfaces. Surfactant and biosurfactant-based formulations, with and without added protease, were screened for cleaning performance. Enzyme-free detergent formulations at 1500 ppm total surfactant were insufficient to cause complete surface cleaning, despite the high concentration of surfactant. The cleaning performance of a "home-made" formulation containing 2 ppm subtilisin A (SA) and 2 ppm sodium dodecyl benzyl sulphonate (SDOBS) was as efficient as the best amongst the three enzyme-free 1500 ppm formulations. The cleaning performance of 2 ppm SA in the absence of SDOBS was less effective than the combined formulation, even though 2 ppm SDOBS alone did not cause any protein removal. The observed synergistic performance was attributed to the cooperative mechanisms (chemical and physical attack) by which these two agents act on a rubisco stain. Replacing SDOBS in the enzyme-surfactant formulation with the same amount of surfactin biosurfactant (2 ppm) gave the best rubisco removal of all formulations examined in this study, irrespective of the surface chemistry underlying the protein film. It was found that 75% and 80% of immobilised rubisco stain could be removed from hydrophobic and hydrophilic surfaces, respectively, by the biosurfactant-SA formulation (compared with 60% and 65%, respectively, using the SDOBS-SA formulation). Our results suggest that it may be possible to generate fully renewable biochemical-based cleaning formulations that have superior cleaning performance to existing technologies. In developing optimised formulations, there is a pressing need for chip-based tools similar to that developed in this research.

  6. 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.

  7. Reduction of trapped-ion anomalous heating by in situ surface plasma cleaning

    NASA Astrophysics Data System (ADS)

    McConnell, Robert; Bruzewicz, Colin; Chiaverini, John; Sage, Jeremy

    2015-08-01

    Anomalous motional heating is a major obstacle to scalable quantum information processing with trapped ions. Although the source of this heating is not yet understood, several previous studies suggest that noise due to surface contaminants is the limiting heating mechanism in some instances. We demonstrate an improvement by a factor of 4 in the room-temperature heating rate of a niobium surface electrode trap by in situ plasma cleaning of the trap surface. This surface treatment was performed with a simple homebuilt coil assembly and commercially available matching network and is considerably gentler than other treatments, such as ion milling or laser cleaning, that have previously been shown to improve ion heating rates. We do not see an improvement in the heating rate when the trap is operated at cryogenic temperatures, pointing to a role of thermally activated surface contaminants in motional heating whose activity may freeze out at low temperatures.

  8. [Physicochemical fundamentals on the cleaning of hard surfaces (author's transl)].

    PubMed

    Schwuger, M J; Kurzendörfer, C P

    1979-03-01

    The primary process in the cleaning of hard surfaces is the adsorption of the active substance of the detergent at the interfaces: liquid/gas, liquid/liquid, liquid/solid. This primary step in the cleaning process induces secondary processes which in turn are responsible for the soil removal from the surface of the substrate. The first requirement for a cleaning effect is that the dirt and the substrate be well wetted by the cleaning solution as a result of a reduction in surface tension and of the adsorption at the solid/liquid interface. The further secondary processes which effect the removal of dirt vary considerably, depending on the type of dirt (e.g. oils, pigments). In the case of oily and greasy dirt, rolling-up penetration, formation of mixed phases, emulsification and solubilization are of importance. For pigments, the surface pressure of the adsorption layer and the electrostatic repulsion are the determining factors. The processes of pigment dispersion, emulsification and solubilization are, in addition, extremely important for the stabilization of the dirty wash bath and the prevention of deposits on the substrate. The essential active substances of the detergents are surfactant and complexing agents, the first being unspecifically adsorbed by hydrophobic interactions, and the latter specifically by polar interactions. They influence one another mutually and are responsible for an optimal cleaning effect when they occur in suitable mixing ratios; the special constitutional characteristics of the individual surfactant and complexing agents, must also be considered.

  9. Surface cleaning of metal wire by atmospheric pressure plasma

    NASA Astrophysics Data System (ADS)

    Nakamura, T.; Buttapeng, C.; Furuya, S.; Harada, N.

    2009-11-01

    In this study, the possible application of atmospheric pressure dielectric barrier discharge plasma for the annealing of metallic wire is examined and presented. The main purpose of the current study is to examine the surface cleaning effect for a cylindrical object by atmospheric pressure plasma. The experimental setup consists of a gas tank, plasma reactor, and power supply with control panel. The gas assists in the generation of plasma. Copper wire was used as an experimental cylindrical object. This copper wire was irradiated with the plasma, and the cleaning effect was confirmed. The result showed that it is possible to remove the tarnish which exists on the copper wire surface. The experiment reveals that atmospheric pressure plasma is usable for the surface cleaning of metal wire. However, it is necessary to examine the method for preventing oxidization of the copper wire.

  10. High-Power Ultrasound in Surface Cleaning and Decontamination

    NASA Astrophysics Data System (ADS)

    Awad, Sami B.

    High-power ultrasound is being widely utilized for decontamination in different industrial applications. The same technology is also being investigated as an effective tool for cleaning of components in the decontamination of produce. An understanding of the basic technology and how it works in cleaning various industrial parts should help in applying it on a large scale in the food industry. The technology has evolved throughout the past four decades. Different frequencies were developed and are now industrially available. The frequency range is from 20 kHz to 1 MHz. Current sound technology provides a uniform ultrasonic activity throughout the cleaning vessel, which was a major disadvantage in the earlier technology. The two main driving forces that affect cleaning of surfaces are cavitation and acoustic streaming. Both are generated as a result of the direct interaction of high-frequency sound waves with fluids.

  11. Effect of melamine foam cleaning on the surface condition of composite resin artificial teeth.

    PubMed

    Tanaka, Rika; Kurogi, Tadafumi; Murata, Hiroshi

    2013-12-01

    The purpose of this study was to examine the abrasive and cleaning effects of melamine foam and other cleaning agents on the surfaces of composite resin artificial tooth specimens. A stained composite resin artificial tooth in a used denture was cleaned using a denture brush and melamine foam, and the stain removal effect was evaluated macroscopically. Next, 5 types of cleaning material (fourfold-compression melamine foam, MEL; brush with water, BRU; denture dentifrice without abrasive, POL; denture dentifrice with abrasive, TAF; conventional dentifrice, AQU) and 15 plate-shaped specimens made of composite resin for artificial teeth were used for wear tests. The surface roughness was measured using a laser scanning microscope. Furthermore, the surface properties were observed using a digital microscope. Surface roughness data were analyzed by two-way ANOVA followed by Tukey's test. Artificial tooth stains that could not be removed by brushing became removable using melamine foam. With regard to surface roughness in the context of the wear test, significant differences were not indicated between MEL and POL, whereas BRU-, TAF-, and AQU-treated specimens showed significantly increased surface roughness (p < 0.05). In the comparison among the cleaning materials, TAF- and AQU-treated specimens showed significantly rougher surfaces than those treated with MEL, BRU, and POL (p < 0.05). Macroscopic observations suggest that melamine foam would be effective for the removal of stains on composite resin artificial teeth. Traces of wear were not observed in specimens treated with melamine foam and the denture dentifrice not containing abrasives. It was suggested that these two materials would be desirable and useful to use for composite resin tooth cleaning. © 2013 by the American College of Prosthodontists.

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

    SciTech Connect

    Saghir, M. E-mail: G.Balakrishnan@warwick.ac.uk; Walker, M.; McConville, C. F.; Balakrishnan, G. E-mail: G.Balakrishnan@warwick.ac.uk

    2016-02-08

    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.

  13. 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.

  14. Cleaning and characterization of objects of cultural value by laser ablation

    NASA Astrophysics Data System (ADS)

    Bilmes, Gabriel M.; Freisztav, Cesar; Schinca, Daniel; Orsetti, Alberto

    2005-06-01

    Surface ablation with nanosecond laser pulses was applied to preservation, cleaning and compositional identification of objects of cultural value. On one hand, treatments of fabrics, coins, bones, and other archeological objects are shown, as well as applications to the preservation of covers, front of books and old manuscripts made in rag paper. Damage fluence thresholds for 17 different XIXth century types of papers, made by processing textiles, were determined. On the other hand, we use the spectroscopic analysis of the plasma generated as a result of laser ablation (LIBS- laser Induced Breakdown Spectroscopy-) for the determination of the elementary composition of unique pieces in anthropology and archaeology. In particular, we show applications to the identification of trace elements in Hominide teeth, of interest concerning the analysis of eating habits. We also apply LIBS to the determination of the composition of acheological objects belonging to different pre-Columbian cultures.

  15. 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.

  16. Self-cleaning of Surfaces: the Role of Surface Wettability and Dust Types

    NASA Astrophysics Data System (ADS)

    Quan, Yun-Yun; Zhang, Li-Zhi; Qi, Rong-Hui; Cai, Rong-Rong

    2016-12-01

    The self-cleaning property is usually connected to superhydrophobic surfaces (SHSs) where the dust particles can be easily removed by the rolling motion of droplets. It seems that superhydrophobicity (its durability is questionable nowadays) is a necessity. However here, it is disclosed that self-cleaning can also be realized on an ordinary surface by droplet impinging. The effects of surface wettability and the types of dust particles are considered. The self-cleaning is realized by two steps: (1) the pickup of particles by the water-air interface of an impinging droplet, (2) the release of the impinging droplets from the surface. It can be observed that only the trailing edges of the droplets can pick up particles when the droplets recoil from the inclined surfaces. The hydrophilic surface can also achieve self-cleaning under some conditions. This interesting finding may be helpful for the successful implementation of self-cleaning with common surfaces.

  17. Self-cleaning of Surfaces: the Role of Surface Wettability and Dust Types

    PubMed Central

    Quan, Yun-Yun; Zhang, Li-Zhi; Qi, Rong-Hui; Cai, Rong-Rong

    2016-01-01

    The self-cleaning property is usually connected to superhydrophobic surfaces (SHSs) where the dust particles can be easily removed by the rolling motion of droplets. It seems that superhydrophobicity (its durability is questionable nowadays) is a necessity. However here, it is disclosed that self-cleaning can also be realized on an ordinary surface by droplet impinging. The effects of surface wettability and the types of dust particles are considered. The self-cleaning is realized by two steps: (1) the pickup of particles by the water-air interface of an impinging droplet, (2) the release of the impinging droplets from the surface. It can be observed that only the trailing edges of the droplets can pick up particles when the droplets recoil from the inclined surfaces. The hydrophilic surface can also achieve self-cleaning under some conditions. This interesting finding may be helpful for the successful implementation of self-cleaning with common surfaces. PMID:27917900

  18. 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.

  19. 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

  20. 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.

  1. Beam cleaning of an incoherent laser via plasma Raman amplification

    DOE PAGES

    Edwards, Matthew R.; Qu, Kenan; Mikhailova, Julia M.; ...

    2017-09-25

    We show that backward Raman amplification in plasma can efficiently compress a temporally incoherent pump laser into an intense coherent amplified seed pulse, provided that the correlation time of the pump is longer than the inverse plasma frequency. One analytical theory for Raman amplification using pump beams with different correlation functions is developed and compared to numerical calculations and particle-in-cell simulations. Since incoherence on scales shorter than the instability growth time suppresses spontaneous noise amplification, we point out a broad regime where quasi-coherent sources may be used as efficient low-noise Raman amplification pumps. As the amplified seed is coherent, Ramanmore » amplification provides an additional a beam-cleaning mechanism for removing incoherence. At near-infrared wavelengths, finite coherence times as short as 50 fs allow amplification with only minor losses in efficiency.« less

  2. Beam cleaning of an incoherent laser via plasma Raman amplification

    NASA Astrophysics Data System (ADS)

    Edwards, Matthew R.; Qu, Kenan; Mikhailova, Julia M.; Fisch, Nathaniel J.

    2017-10-01

    We show that backward Raman amplification in plasma can efficiently compress a temporally incoherent pump laser into an intense coherent amplified seed pulse, provided that the correlation time of the pump is longer than the inverse plasma frequency. An analytical theory for Raman amplification using pump beams with different correlation functions is developed and compared to numerical calculations and particle-in-cell simulations. Since incoherence on scales shorter than the instability growth time suppresses spontaneous noise amplification, we point out a broad regime where quasi-coherent sources may be used as efficient low-noise Raman amplification pumps. As the amplified seed is coherent, Raman amplification additionally provides a beam-cleaning mechanism for removing incoherence. At near-infrared wavelengths, finite coherence times as short as 50 fs allow amplification with only minor losses in efficiency.

  3. Bubble bouncing at a clean water surface.

    PubMed

    Zawala, Jan; Dorbolo, Stéphane; Vandewalle, Nicolas; Malysa, Kazimierz

    2013-10-28

    Experiments on the coalescence time of submillimeter bubbles colliding with a distilled water/air interface either being at rest (undisturbed) or vibrating vertically (with controlled amplitude and frequency) were carried out. It was found that the outcome of the bubble collision (coalescence or bounce) depends on impact velocity and size of the bubble, i.e. the parameters determining the bubble deformation degree. With the surface at rest, when the deformation of the bubble was sufficiently high, bubble bouncing was observed. It was caused by the fact that the radius of the intervening liquid film formed between the colliding bubble and water/air interface was large enough to prevent the liquid layer from reaching its thickness of rupture within the time of bubble-interface contact. Coalescence occurred in a consecutive collision if the bubble deformation was below a threshold value, as a result of dissipation of the kinetic energy associated with the bubble motion. The hypothesis about the crucial role of the bubble deformation and size of the liquid film formed in the bouncing mechanism was confirmed in a series of experiments where the bubble collided with a vibrating water/air interface. It was shown that when the kinetic energy was properly re-supplied from an external source (interface vibrations), the spectacular phenomenon of "immortal" bubbles, dancing indefinitely at the water/air interface, was achieved. It was shown that "immortal" bubble formation is a consequence of a similarly high degree of the bubble shape deformation and consequently a large enough radius of the liquid film formed.

  4. 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.

  5. Poultices as a Way to Eliminate the Yellowing Effect Linked to Limestone Laser Cleaning

    NASA Astrophysics Data System (ADS)

    Vergès-Belmin, Véronique; Labouré, M.

    One of the main drawbacks raised against stone cleaning by Nd:YAG Q-switched lasers (1,064 nm, 6-20 ns) is the yellow aspect left after cleaning. It is well known among stone conservators that one may attenuate this colour using waterbased poultices.We tested four kinds of poultices in two areas on the northern portal of the Saint Denis cathedral, which had been laser cleaned in 1997. The yellow aspect visibly decreased immediately after poultice removal, and the effect remained visible after 12 months. Colour measurements performed before, just after, 3 and 9 months after poulticing confirmed and quantified observations. Scotch tape tests, optical microscope and SEM-EDS observations and analyses show that this reduction is due at least partly to poultice remnants when poultice contains attapulgite or carboxymethyl- cellulose. Fume silica poulticing also seems to leave relics on the treated surface. The use of cellulose alone leads to a slight de-yellowing without any poultice relics being present. In that case, the de-yellowing could be due to solubilization of yellow products or physical detachment of particles.

  6. 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.

  7. Air cushion convection inhibiting icing of self-cleaning surfaces.

    PubMed

    Yang, Qin; Luo, Zhuangzhu; Jiang, Faming; Luo, Yimin; Tan, Sheng; Lu, Zhibin; Zhang, Zhaozhu; Liu, Weimin

    2016-10-04

    Anti-icing surfaces/interfaces are of considerable importance in various engineering fields under natural freezing environment. Although superhydrophobic self-cleaning surfaces show good anti-icing potentials, promotion of these surfaces in engineering applications seems to enter a "bottleneck" stage. One of the key issues is the intrinsic relationship between superhydrophobicity and icephobicity is unclear, and the dynamic action mechanism of "air cushion" (a key internal factor for superhydrophobicity) on icing suppression was largely ignored. Here we report that icing inhibition (i.e. icing-delay) of self-cleaning surfaces is mainly ascribed to air cushion and its convection. We experimentally found air cushion on the porous self-cleaning coating under vacuum environments and on the water/ice-coating interface at low temperatures. The icing-delay performances of porous self-cleaning surfaces compared with bare substrate, up to 10~40min under 0~-4(°)C environments close to freezing rain, have been accurately real-time recorded by a novel synergy method including high-speed photography and strain sensing voltage. Based on the experimental results, we innovatively propose a physical model of "air cushion convection inhibiting icing", which envisages both the static action of trapped air pocket without air flow and dynamic action of air cushion convection. Gibbs free energy of water droplets increased with the entropy of air derived from heat and mass transfer between warmer air underneath water droplets and colder surrounding air, resulting in remarkable ice nucleation delay. Only when air cushion convection disappears can ice nucleation be triggered on suitable Gibbs free energy conditions. The fundamental understanding of air cushion on anti-icing is an important step towards designing optimal anti-icing surfaces for practical engineering application.

  8. 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.

  9. Wetting and self-cleaning properties of artificial superhydrophobic surfaces.

    PubMed

    Fürstner, Reiner; Barthlott, Wilhelm; Neinhuis, Christoph; Walzel, Peter

    2005-02-01

    The wetting and the self-cleaning properties (the latter is often called the "Lotus-Effect") of three types of superhydrophobic surfaces have been investigated: silicon wafer specimens with different regular arrays of spikes hydrophobized by chemical treatment, replicates of water-repellent leaves of plants, and commercially available metal foils which were additionally hydrophobized by means of a fluorinated agent. Water droplets rolled off easily from those silicon samples which had a microstructure consisting of rather slender spikes with narrow pitches. Such samples could be cleaned almost completely from artificial particulate contaminations by a fog consisting of water droplets (diameter range, 8-20 microm). Some metal foils and some replicates had two levels of roughening. Because of this, a complete removal of all particles was not possible using artificial fog. However, water drops with some amount of kinetic impact energy were able to clean these surfaces perfectly. A substrate where pronounced structures in the range below 5 microm were lacking could not be cleaned by means of fog because this treatment resulted in a continuous water film on the samples.

  10. 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.

  11. Probing the limits of paper and parchment laser cleaning by multispectral imaging

    NASA Astrophysics Data System (ADS)

    Kautek, Wolfgang; Pentzien, Simone; Mueller-Hess, Doris; Troschke, Karin; Teule, Rianne

    2001-10-01

    Paper and parchment cleaning with lasers provides the advantage to be a contact-less and dry process. The absence of chemical agents, its spectroscopic selectivity, micro-precision, computer-aided handling, and the combination with on-line diagnostic techniques makes it attractive for restoration applications. This technique, however, is not only limited by the evaporation of such delicate protein or cellulose fibre structures (i.e. the ablation threshold) or by discolorations, which can be easily detected by the naked eye or by microscopic inspection. Even when the aesthetic appearance is not altered, invisible irreversible chemical modifications may affect the long-term aging behavior negatively. In such cases, only diagnostic tools sensitive for chemical changes can probe the limits of laser cleaning. Deviations of chemical conversion threshold fluences from the well-established ablation threshold fluence values were investigated by multi-spectral imaging techniques at parchment or paper model systems and historical originals. Ultraviolet, visible and infrared reflection, but also visible fluorescence were employed using an imaging system, which operates in a spectral range from 320 nm to 1550 nm. Visible imaging allowed an accurate documentation of the color appearance of the artwork before and after the laser treatment. In-depth information of chemical modifications could be gained by the infrared imaging mode. Surface chemical identification was performed by both diffuse-reflection imaging in the ultraviolet range between 320 and 400 nm, and by visible fluorescence imaging using a 365 nm light source. The results for excimer laser treatment at 308 nm show that not only the laser fluence but also the age of the artefact strongly affects the chemical conversion threshold. Most substrates older than at least several decades exhibited much higher chemical stability than new model systems. This is a strong indication that the aging status of both parchment and

  12. Cleaning of biomaterial surfaces: protein removal by different solvents.

    PubMed

    Kratz, Fabian; Grass, Simone; Umanskaya, Natalia; Scheibe, Christian; Müller-Renno, Christine; Davoudi, Neda; Hannig, Matthias; Ziegler, Christiane

    2015-04-01

    The removal of biofilms or protein films from biomaterials is still a challenging task. In particular, for research investigations on real (applied) surfaces the reuse of samples is of high importance, because reuse allows the comparison of the same sample in different experiments. The aim of the present study was to evaluate the cleaning efficiency of different solvents (SDS, water, acetone, isopropanol, RIPA-buffer and Tween-20) on five different biomaterials (titanium, gold, PMMA (no acetone used), ceramic, and PTFE) with different wettability which were covered by layers of two different adsorbed proteins (BSA and lysozyme). The presence of a protein film after adsorption was confirmed by transmission electron microscopy (TEM). After treatment of the surfaces with the different solvents, the residual proteins on the surface were determined by BCA-assay (bicinchoninic acid assay). Data of the present study indicate that SDS is an effective solvent, but for several protein-substrate combinations it does not show the cleaning efficiency often mentioned in literature. RIPA-buffer and Tween-20 were more effective. They showed very low residual protein amounts after cleaning on all examined material surfaces and for both proteins, however, with small differences for the respective substrate-protein combinations. RIPA-buffer in combination with ultrasonication completely removed the protein layer as confirmed by TEM.

  13. 40 CFR 761.372 - Specific requirements for relatively clean surfaces.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... clean surfaces. 761.372 Section 761.372 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... § 761.372 Specific requirements for relatively clean surfaces. For surfaces that do not appear dusty or... with clean rinse solvent such that the entire surfaces is very wet for 1 minute. Drain and contain...

  14. 40 CFR 761.372 - Specific requirements for relatively clean surfaces.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... clean surfaces. 761.372 Section 761.372 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... § 761.372 Specific requirements for relatively clean surfaces. For surfaces that do not appear dusty or... with clean rinse solvent such that the entire surfaces is very wet for 1 minute. Drain and contain...

  15. Si cleaning method without surface morphology change by cyanide solutions

    NASA Astrophysics Data System (ADS)

    Takahashi, Masao; Liu, Yueh-Ling; Narita, Hiroaki; Kobayashi, Hikaru

    2008-04-01

    Hydrogen cyanide (HCN) aqueous solutions can remove copper contaminants from Si surfaces more effectively than hydrochloric acid/hydrogen peroxide mixture (HPM) and sulfuric acid/hydrogen peroxide mixture (SPM). When pH of the HCN solutions is adjusted at 9, Si surface morphology is not changed, while when pH exceeds 10, the Si surfaces are considerably roughed. AFM measurements show that Cu contaminants are present in the form of particles on the bare Si surfaces. XPS measurements show that the particles consist of metallic Cu. The Cu particle height decreases almost linearly with the cleaning time, and the Cu surface concentration decreases exponentially with it. It is concluded that Cu particles gradually dissolve into the HCN aqueous solutions by the direct reaction with cyanide ions at the surface of the Cu particles.

  16. Phonons on the clean metal surfaces and in adsorption structures

    NASA Astrophysics Data System (ADS)

    Rusina, Galina G.; Chulkov, Evgenii V.

    2013-06-01

    The state-of-the-art studies of the vibrational dynamics of clean metal surfaces and metal surface structures formed upon the sub-monolayer adsorption of the atoms of various elements are considered. A brief historical survey of the milestones of investigations of surface phonons is presented. The results of studies of the atomic structure and vibration characteristics of surfaces with low and high Miller indices and adsorption structures are analyzed. It is demonstrated that vicinal surfaces of FCC metals tend to exhibit specific vibrational modes located on the step and polarized along the step. Irrespective of the type and position of adsorption or the substrate structure, the phonon spectra of sub-monolayer adsorption structures always tend to display two modes for combined translational displacements of adatoms and for coupled vibrations of substrate atoms and adatoms polarized in the direction normal to the surface. The bibliography includes 202 references.

  17. The dream of staying clean: Lotus and biomimetic surfaces.

    PubMed

    Solga, Andreas; Cerman, Zdenek; Striffler, Boris F; Spaeth, Manuel; Barthlott, Wilhelm

    2007-12-01

    The Lotus has been the symbol of purity for thousands of years; contaminations and pathogens are washed off the surfaces of Lotus and some other plants with rain or even dew. After the introduction of scanning electron microscopy, we were able to resolve the mechanism behind this phenomenon. It took some further decades before in-depth studies on self-cleaning with plants were conducted and the effect could be understood in detail. We identified extreme water-repellency ('superhydrophobicity'), characterized by very high contact angles and low sliding angles, as the prerequisite for self-cleaning properties. We could show that the combination of two factors is necessary for obtaining a high degree of water-repellency: (1) low energy surfaces being hydrophobic and (2) surface structures that significantly increase hydrophobicity. It is suggested that this mechanism plays an important role in the protection of plants against pathogens. Our technological application of this effect has resulted in the development of successful, eco-friendly and sustainable industrial products. Another interesting property was found with superhydrophobic surfaces of certain aquatic and semi-aquatic plants and animals: here a layer of air under water is retained. We present a new approach of using this feature for creating structured, air-retaining surfaces for technical underwater applications. It is proposed that such surfaces can reduce significantly the drag of large ships. We conclude that basic biological research is of particular importance for true innovation. Our research on superhydrophobic self-cleaning biological surfaces and the development of similar engineered materials suggests that biomimicry is a matter of multi-stage processes rather than a simple copying of biological developments.

  18. 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.

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

    NASA Astrophysics Data System (ADS)

    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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Producing lasting amphiphobic building surfaces with self-cleaning properties

    NASA Astrophysics Data System (ADS)

    Facio, Dario S.; Carrascosa, Luis A. M.; Mosquera, María J.

    2017-06-01

    Nowadays, producing building surfaces that prevent water and oil uptake and which present self-cleaning activity is still a challenge. In this study, amphiphobic (superhydrophobic and oleophobic) building surfaces were successfully produced. A simple and low-cost process was developed, which is applicable to large-scale building surfaces, according the following procedure: (1) by spraying a SiO2 nanocomposite which produces a closely-packed nanoparticle uniform topography; (2) by functionalizing the previous coating with a fluorinated alkoxysilane, producing high hydrophobicity and oleophobicity. The formation of a Cassie-Baxter regime, in which air pockets could be trapped between the aggregates of particles, was confirmed by topographic study. The building surface demonstrated an excellent self-cleaning performance. Finally, the surface presented lasting superhydrophobicity with high stability against successive attachment/detachment force cycles. This high durability can be explained by the effective grafting of the silica nanocomposite coating skeleton with the substrate, and with the additional fluorinated coating produced by condensation reactions.

  5. 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.

  6. An Evaluation of Nd:YAG Laser-Cleaned Basketry in Comparison with Commonly Used Methods

    NASA Astrophysics Data System (ADS)

    Elliott, A.; Bezúr, A.; Thornton, J.

    While in storage and on exhibition, baskets can accumulate dirt that is aesthetically undesirable and even harmful. The nature of the woven structure, as well as the porosity of organic materials, causes difficulty in the removal of accumulated dirt. This chapter presents results from a study of basket-cleaning methods focusing on how Nd:YAG laser-cleaned samples are compare with those cleaned by more commonly used methods. Cleaning tests were performed on stem, bark, and root sample materials in order to examine the effects of cleaning on a variety of plant materials that are commonly encountered with basketry. Photography, optical microscopy, and scanning electron microscopy were used to document and compare the effectiveness and drawbacks of these methods. The results indicated that plant materials with protective cuticle layers can be effectively cleaned using lowtech methods and such fibers would not greatly benefit from laser cleaning. Materials without protective cuticle layers are more sensitive to mechanical cleaning and could possibly be more safely cleaned using lasers.

  7. Metallic surfaces decontamination by using laser light

    SciTech Connect

    Moggia, Fabrice; Lecardonnel, Xavier

    2013-07-01

    Metal surface cleaning appears to be one of the major priorities for industries especially for nuclear industries. The research and the development of a new technology that is able to meet the actual requirements (i.e. waste volume minimization, liquid effluents and chemicals free process...) seems to be the main commitment. Currently, a wide panel of technologies already exists (e.g. blasting, disk sander, electro-decontamination...) but for some of them, the efficiency is limited (e.g, Dry Ice blasting) and for others, the wastes production (liquid and/or solid) remains an important issue. One answer could be the use of a LASER light process. Since a couple of years, the Clean- Up Business Unit of the AREVA group investigates this decontamination technology. Many tests have been already performed in inactive (i.e. on simulants such as paints, inks, resins, metallic oxides) or active conditions (i.e. pieces covered with a thick metallic oxide layer and metallic pieces covered with grease). The paper will describe the results obtained in term of decontamination efficiency during all our validation process. Metallographic characterizations (i.e. SEM, X-ray scattering) and radiological analysis will be provided. We will also focus our paper on the future deployment of the LASER technology and its commercial use at La Hague reprocessing facility in 2013. (authors)

  8. 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.

  9. Cleaning of magnetic nanoparticle surfaces via cold plasmas treatments

    NASA Astrophysics Data System (ADS)

    Poudyal, Narayan; Han, Guangbing; Qiu, Zhaoguo; Elkins, Kevin; Mohapatra, Jeotikanta; Gandha, Kinjal; Timmons, Richard B.; Liu, J. Ping

    2017-05-01

    We report surface cleaning of magnetic nanoparticles (SmCo5 nanochips and CoFe2O4 nanoparticles) by using cold plasma. SmCo5 nanochips and CoFe2O4 nanoparticles, coated with surfactants (oleic acid and oleylamine, respectively) on their surfaces, were treated in cold plasmas generated in argon, hydrogen or oxygen atmospheres. The plasmas were generated using a capacitively coupled pulsed radio frequency discharge. Surface cleaning of nanoparticles was monitored by measurement of the reduction of surface carbon content as functions of plasma processing parameters and treatment times. EDX and XPS analyses of the nanoparticles, obtained after the plasma treatment, revealed significant reduction of carbon content was achieved via plasma treatment. The SmCo5 nanochips and CoFe2O4 nanoparticles treated in an argon plasma revealed reduction of atomic carbon content by more than 54 and 40 in atomic percentage, compared with the untreated nanoparticles while the morphology, crystal structures and magnetic properties are retained upon the treatments.

  10. Roughening and removal of surface contamination from beryllium using negative transferred-arc cleaning

    SciTech Connect

    Castro, R.G.; Hollis, K.J.; Elliott, K.E.

    1997-12-01

    Negative transferred-arc (TA) cleaning has been used extensively in the aerospace industry to clean and prepare surfaces prior to plasma spraying of thermal barrier coatings. This non-line of sight process can improve the bond strength of plasma sprayed coatings to the substrate material by cleaning and macroscopically roughening the surface. A variation of this cleaning methodology is also used in gas tungsten arc (GTA) welding to cathodically clean the surfaces of aluminum and magnesium prior to welding. Investigations are currently being performed to quantify the degree in which the negative transferred-arc process can clean and roughen metal surfaces. Preliminary information will be reported on the influence of processing conditions on roughening and the removal of carbon and other contaminates from the surface of beryllium. Optical, spectral and electrical methods to quantify cleaning of the surface will also be discussed. Applications for this technology include chemical-free precision cleaning of beryllium components.

  11. Uv Laser-Induced Dehydroxylation of UV Fused Silica Surfaces

    NASA Astrophysics Data System (ADS)

    Fernandes, A. J.; Kane, D. M.; Gong, B.; Lamb, R. N.

    The 'clean' surface of silica glass is usually covered with a quasi-layer of hydroxyl groups. These groups are significant as their concentration on a surface affects surface adhesion and chemical reactivity. Removal of hydroxyl groups from the surface by a UV pulsed laser treatment has been demonstrated to be an alternative technique to the dehydroxylation of glass by the traditional oven heat treatment. Silica so treated has improved resistance to particulate adhesion. Dehydroxylation using this UV laser treatment has key advantages of being: a much faster process; largely limited to heating the surface not the bulk of the silica; and which allows selective spatial patterning of the dehydroxylation of the silica surface. This work outlines a technique developed to allow systematic, quantitative measurements of the dehydroxylation of UV fused silica. The removal of hydroxyl groups using laser irradiation is shown to be a thermal process.

  12. Shockwave-induced deformation of organic particles during laser shockwave cleaning

    NASA Astrophysics Data System (ADS)

    Hoon Kim, Tae; Cho, Hanchul; Busnaina, Ahmed; Park, Jin-Goo; Kim, Dongsik

    2013-08-01

    Although the laser shockwave cleaning process offers a promising alternative to conventional dry-cleaning processes for nanoscale particle removal, its difficulty in removing organic particles has been an unexplained problem. This work elucidates the physics underlying the ineffectiveness of removing organic particles using laser shock cleaning utilizing polystyrene latex particles on silicon substrates. It is found that the shockwave pressure is high enough to deform the particles, increasing the contact radius and consequently the particle adhesion force. The particle deformation has been verified by high-angle scanning electron microscopy. The Maugis-Pollock theory has been applied to predict the contact radius, showing good agreement with the experiment.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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)

  19. Axial laser beam cleaning of tiny particles on narrow slot sidewalls

    NASA Astrophysics Data System (ADS)

    Yue, Liyang; Wang, Zengbo; Guo, Wei; Li, Lin

    2012-09-01

    Laser cleaning is a rapidly developed technique in recent years. However, it is difficult to apply it to a slot structure, because the sidewall cannot absorb enough laser energy. Meanwhile, the focusing lens concentrates the laser beam and energy on a small spot size at the focusing position. The defocused laser beam after the focusing position would disperse and spatially enlarge. In this study, an axial laser beam (excimer laser, 248 nm) is focused at a position that is slightly in front of the slot (silicon), which makes the defocused beam propagate into the slot, and the sidewall is able to absorb the laser energy through its dispersion. The slot structure is constructed through a combination of three silicon wafers (two as sidewalls, and one as the bottom of the slot). In this manner the slot width can be controlled well during the experiment. Using this method, tiny particles (fused silica, diameter 5 µm) adhered on the slot sidewall are successfully cleaned. The cleaning threshold and efficiency for multiple slot widths (3.5-13 mm) and pulse numbers (0-40) are experimentally determined. A multi-physics model is established to understand the experimental phenomena. The electromagnetic-thermal-mechanical processes during laser cleaning are also analysed.

  20. 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.

  1. 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.

  2. Contamination spike simulation and measurement in a clean metal vapor laser

    SciTech Connect

    Lin, C.E. ); Yang, C.Y. )

    1990-04-01

    This paper describes a new method for the generation of contamination-induced voltage spikes in a clean metal vapor laser. The method facilitates the study of the characteristics of this troublesome phenomenon in laser systems. Analysis of these artificially generated dirt spikes shows that the breakdown time of the laser tube is increased when these spike appear. The concept of a Townsend discharge is used to identify the parameter which changes the breakdown time of the discharges. The residual ionization control method is proposed to generate dirt spikes in a clean laser. Experimental results show that a wide range of dirt spike magnitudes can be obtained by using the proposed method. The method provides easy and accurate control of the magnitude of the dirt spike, and the laser tube does not become polluted. Results based on the measurements can be used in actual laser systems to monitor the appearance of dirt spikes and thus avoid the danger of thyratron failure.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. Investigation of the effect of contaminations and cleaning processes on the surface properties of brazing surfaces

    NASA Astrophysics Data System (ADS)

    Bobzin, K.; Öte, M.; Wiesner, S.

    2017-03-01

    The quality of brazed joints is determined by different factors such as the atmosphere and the parameters during brazing as well as the condition of the brazing surfaces. Residues of lubricants used during machining of the components and the subsequent cleaning processes can contaminate the faying surfaces and can hence influence the flow ability of the molten filler metals. Besides their influence on the filler metal flow, the residues can result in the formation of carbonic phases in the joint leading to a possible reduction of the corrosion resistance and the mechanical properties. The first step of the current study with the aim of avoiding these defects is to identify the influence of critical contaminations and cleaning methods on the quality of the brazed joints. In a first step, contaminations on AISI304 and Inconel alloy 625 due to different cooling lubricants and the effect of several cleaning methods, in particular plasma cleaning, have been investigated. Information about the surface energy of contaminated and cleaned surfaces was gained by measuring contact angle of testing fluids. Additionally, the lubricants and the resulting contamination products have been analyzed considering the influence of a heat treatment.

  10. 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.

  11. 40 CFR 761.372 - Specific requirements for relatively clean surfaces.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... clean surfaces. 761.372 Section 761.372 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY..., DISTRIBUTION IN COMMERCE, AND USE PROHIBITIONS Double Wash/Rinse Method for Decontaminating Non-Porous Surfaces § 761.372 Specific requirements for relatively clean surfaces. For surfaces that do not appear dusty or...

  12. Laser cleaning of particulates from paper: Comparison between sized ground wood cellulose and pure cellulose

    NASA Astrophysics Data System (ADS)

    Arif, S.; Kautek, W.

    2013-07-01

    Visible laser cleaning of charcoal particulates from yellow acid mechanical ground wood cellulose paper was compared with that from bleached sulphite softwood cellulose paper. About one order of magnitude of fluence range is available for a cleaning dynamics between the cleaning threshold and the destruction threshold for two laser pulses. Wood cellulose paper exhibited a higher destruction threshold of the original paper than that of the contaminated specimen because of heat transfer from the hot or evaporating charcoal particulates. In contrast, the contaminated bleached cellulose paper exhibited a higher destruction threshold due to shading by the particulates. The graphite particles are not only detached thermo-mechanically, but also by evaporation or combustion. A cleaning effect was found also outside the illuminated areas due to lateral blasting. Infrared measurements revealed dehydration/dehydrogenation reactions and cross-links by ether bonds together with structural changes of the cellulose chain arrangement and the degree of crystallinity.

  13. Damage Free Particle Removal from Extreme Ultraviolet Lithography Mask Layers by High Energy Laser Shock Wave Cleaning

    NASA Astrophysics Data System (ADS)

    Kim, Tae-Gon; Yoo, Young-Sam; Kim, Tae-Geun; Ahn, Jinho; Lee, Jong-Myoung; Choi, Jae-Sung; Busnaina, Ahmed A.; Park, Jin-Goo

    2008-06-01

    Plasma shock waves induced by focusing a Q-switched Nd:YAG laser at a maximum energy of 1.8 J in air were characterized by a laser beam deflection method and were applied to 50 nm silica particle removal from a Al2O3/TaN/Ru/MoSi 40 pairs as the extreme ultraviolet lithography (EUVL) mask layers on silicon wafer. A high energy laser induced shock wave effectively removed 50 nm silica particles from the EUVL mask layers. The change of sample topography before and after laser shock cleaning was measured by an atomic force microscope. Surface damage was observed at a gap distance of 1.5 mm. The dimensions of the plasma plume were characterized as a function of the laser energy and focus-to-surface gap distance. The plasma plume was the main source for damaging the surface. A high energy laser induced shock wave with a gap distance of over 3 mm achieved damage-free sub-100 nm particle removal.

  14. 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.

  15. 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.

  16. Cleaning of optical surfaces by capacitively coupled RF discharge plasma

    SciTech Connect

    Yadav, P. K. Rai, S. K.; Nayak, M.; Lodha, G. S.; Kumar, M.; Chakera, J. A.; Naik, P. A.; Mukherjee, C.

    2014-04-24

    In this paper, we report cleaning of carbon capped molybdenum (Mo) thin film by in-house developed radio frequency (RF) plasma reactor, at different powers and exposure time. Carbon capped Mo films were exposed to oxygen plasma for different durations at three different power settings, at a constant pressure. After each exposure, the thickness of the carbon layer and the roughness of the film were determined by hard x-ray reflectivity measurements. It was observed that most of the carbon film got removed in first 15 minutes exposure. A high density layer formed on top of the Mo film was also observed and it was noted that this layer cannot be removed by successive exposures at different powers. A significant improvement in interface roughness with a slight improvement in top film roughness was observed. The surface roughness of the exposed and unexposed samples was also confirmed by atomic force microscopy measurements.

  17. Local atomic structure of a clean surface by surface-extended x-ray absorption fine structure: Amorphized Si

    SciTech Connect

    Comin, F.; Incoccia, L.; Lagarde, P.; Rossi, G.; Citrin, P.H.

    1985-01-14

    The application of near-edge surface, extended x-ray absorption fine structure to the study of a clean surface is reported. Direct evidence is found for surface recrystallization of ion-damaged (amorphized) Si, whereas no such evidence is seen for evaporated (amorphous) Si. The procedures described here are applicable to almost all clean or adsorbate-covered surfaces.

  18. Laser Interaction with Metallic Surfaces.

    DTIC Science & Technology

    1982-12-01

    opaque targets the absorptance is one m~nus the reflectance , measurement of the time dependence of the metal surface reflectance will yield the laser...1O 4 TIME (ps) TIME (ns) (a) REFLECTANCE MEASUREMENTS (b) GENERAL REFLECTANCE WC) REFLECTANCE MEASUREMENT OF SONCH-8RUEVICH et al CURVE OF ZAVECZ et al...integrating sphere by Bonch-Bruevich and, therefore, a total reflectance measurement while Zavecz et al. measured only the specular reflectance. In

  19. 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.

  20. 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...

  1. 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...

  2. 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

  3. Dual Electrolytic Plasma Processing for Steel Surface Cleaning and Passivation

    NASA Astrophysics Data System (ADS)

    Yang, L.; Zhang, P.; Shi, J.; Liang, J.; Tian, W. B.; Zhang, Y. M.; Sun, Z. M.

    2017-07-01

    To remove the rust on rebars and passivate the fresh surfaces, electrodes reversing electrolytic plasma processing (EPP) was proposed and conducted in a 10 wt.% Na2CO3 aqueous solution. The morphology and the composition of the surface were investigated by SEM and XPS. Experimental results show that the rust on the surface was removed effectively by cathode EPP, and a passive film containing Cr2O3 was achieved by the succeeding anode EPP treatment, by a simple operation of reversing the bias. The corrosion resistance was evaluated in a 3.5 wt.% NaCl aqueous solution using an electrochemical workstation. In comparison, the corrosion resistance was improved by the succeeding anode EPP treatment, which is evidenced by a positive shift of the open-circuit potential, an increase in the electrochemical impedance representing the inner layer by 76.8% and the decrease in the corrosion current density by 49.6%. This is an effective and environment-friendly technique to clean and passivate rebars and similar steel materials.

  4. Development of construction specifications to attain clean rooms for the NOVA laser facility

    SciTech Connect

    Benedix, C.P.

    1980-02-01

    This paper describes the process of defining technical requirements for a major Department of Energy Research and Development Facility and subsequent development of construction specifications for the clean spaces in that facility. The organizational interactions between technical client, Engineering and Construction elements are described. The importance of an interdisciplinary team approach is stressed. A brief description of the SHIVA Laser and NOVA Laser Clean Spaces is included to indicate the scope of the facility undertaking. A number of potential pitfalls are discussed that may be helpful to designers of new facilities.

  5. 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.

  6. 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.

  7. 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

  8. Surface modification of plasticized PVC by dry cleaning methods: Consequences for artworks

    NASA Astrophysics Data System (ADS)

    Morales Muñoz, C.

    2010-03-01

    A study of dry cleaning methods for plasticized PVC has been undertaken using three commercial cloths recommended for plastics artworks, in addition to cotton swabs traditionally used in art conservation. The evaluation of the cleaning has focussed on the efficiency of the cleaners, and the physical and chemical damages caused by the cleaning. The physical and chemical modifications of the PVC surface have been studied by optical microscopy, non-contact profilometry and ATR-FTIR spectroscopy, while spectrocolorimetry and non-contact profilometry have been used for evaluating the cleaning efficiency. The results have shown that the cleaner's composition and the cleaning time play an important role in damaging the plasticized PVC surface. On the contrary, it has not been completely determined if the texture of the cleaning agents' surface had an influence on the cleaning efficiency.

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

    NASA Technical Reports Server (NTRS)

    Gillette, R. B.; Beverly, W. D.

    1971-01-01

    Plasma cleaning experiments were completed on hydrocarbon contaminant films, experiments were initiated to determine a satisfactory technique for depositing contaminant films, and an experiment was conducted to determine whether specimens are being thermally cleaned rather than plasma cleaned. Results of plasma cleaning experiments on hydrocarbon contaminant films showed that the optical properties of mirrors and gratings could be satisfactorily restored. Results on fused silica optical flats were inconclusive because of the insensitivity of measurement techniques to the contaminant films. White thermal control surfaces, degraded by the hydrocarbon contaminant film, could not be restored by oxygen plasma exposure. The reflectance of silvered FEP Teflon thermal control surfaces could be restored by plasma cleaning. Experiments with a silicone contaminant indicated that it could not be easily polymerized onto surfaces with ultraviolet radiation. Results of the thermal cleaning experiment showed that the polymerized hydrocarbon contaminant film could not be removed by heating in vacuum to a temperature in excess of that expected during plasma cleaning.

  10. Laser Induced Surface Chemical Epitaxy

    DTIC Science & Technology

    1990-03-01

    Laser-Induced Surface Chemical Epitaxy ( LSCE ). The essential features of LSCE as applied to CdTe epitaxy involve: coadsorption of DMCd and DMTe on a GaAs...DIAGRAM OF THE LSCE PROCESS UHV environment 1M substra1e 9 /X Adsorbed thin film produced CH 3 -Cd-GH 3 CH 3 -Te-CH, by molecular beam source hv ’ CH...with Anneal W/// substraIe %/"/,’ Figure 1.1. Schematic of the LSCE process. (1-2) t I 2. EXPERIMENTAL APPROACH 2.1 Experimental Apparatus The

  11. 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.

  12. 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.

  13. 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.

  14. Organogel-based thin films for self-cleaning on various surfaces.

    PubMed

    Liu, Hongliang; Zhang, Pengchao; Liu, Mingjie; Wang, Shutao; Jiang, Lei

    2013-08-27

    Self-cleaning on various surfaces is obtained using the facile approach of modifying the surface with a thin organogel film. The film not only absorbs oil but also holds it in a crosslinked network, which endows the material with excellent self-cleaning properties. This facile method can be applied to various common engineering metals.

  15. Efficiency of surface cleaning by a glow discharge for plasma spraying coating

    NASA Astrophysics Data System (ADS)

    Kadyrmetov, A. M.; Kashapov, N. F.; Sharifullin, S. N.; Saifutdinov, A. I.; Fadeev, S. A.

    2016-06-01

    The article presents the results of experimental studies of the quality of cleaning steel surfaces by a glow discharge for plasma spraying. Shows the results of measurements of the angle of surface wetting and bond strength of the plasma coating to the surface treated. The dependence of the influence of the glow discharge power, chamber pressure, distance between the electrodes and the processing time of the surface on cleaning efficiency. Optimal fields of factors is found. It is shown increase joint strength coating and base by 30-80% as a result of cleaning the substrate surface by a glow discharge plasma spraying.

  16. 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.

  17. 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.

  18. STUDY OF SURFACE PROPERTIES OF ATOMICALLY-CLEAN METALS AND SEMICONDUCTORS.

    DTIC Science & Technology

    photosorptive effects were observed. In cadmium selenide clean (0001)Cd surfaces were prepared whose properties and chemisorptive behavior were similar to those observed on Cd surfaces of cadmium sulfide. (Author)

  19. Laboratory demonstration model: Active cleaning technique device. [for removal of contaminants from an optical surface

    NASA Technical Reports Server (NTRS)

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

    1974-01-01

    The technique which utilizes exposure to a plasma to remove contaminants from a surface was incorporated into a laboratory model which demonstrates active cleaning by both plasma cleaning and ion sputtering modes of operation. The development phase is reported and includes discussion of the plasma tube configuration, device design, and performance tests. A general description of the active cleaning device is provided which includes information on the main power/plasma discharge sensors, and the power, gas supply, and ion accelerator systems. Development of the active cleaning species at high vacuum conditions is described and results indicate that plasma cleaning occurs in the region of a visible plume which extends from the end of the plasma tube. Recommendations are made for research to determine the plasma cleaning mechanism and the plasma species responsible for the cleaning, as well limitations on the type of contaminants that can be removed.

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

    NASA Astrophysics Data System (ADS)

    Hoppe, E. W.; Seifert, A.; Aalseth, C. E.; Bachelor, P. P.; Day, A. R.; Edwards, D. J.; Hossbach, T. W.; Litke, K. E.; McIntyre, J. I.; Miley, H. S.; Schulte, S. M.; Smart, J. E.; Warren, G. A.

    2007-08-01

    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 +/Cu 2+ 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.

  1. 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

  2. Surface modification of ceramic matrix composites induced by laser treatment

    NASA Astrophysics Data System (ADS)

    Costil, S.; Lukat, S.; Langlade, C.; Coddet, C.

    2008-12-01

    Ceramics or ceramic composites present many advantages (hardness, chemical resistance, low density, etc.) which induce some more and more important applications particularly from the industrial point of view. The evolution of technology can also be beneficial to enlarge their global application areas. This is particularly the aim of this work which consists in applying a laser beam on the ceramic in order to clean its surface. A Nd:YAG laser has been used to study the basic mechanism roughening the surface of silicon carbide composite (ceramic matrix composite (CMC)). Investigations on different surfaces (two chemical compositions) show a strong influence of the nature of the material on the development of a characteristic conic structure. Microscopic studies (SEM) and elementary analyses (EDS and RMS) demonstrated the formation of a regular cone-like structure with a kinetic and a chemical modification specific to each material.

  3. 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.

  4. Surface emitting lasers with combined output

    NASA Technical Reports Server (NTRS)

    Carlin, Donald B. (Inventor)

    1990-01-01

    Surface emitting lasers are laterally aligned and coupled together and also have their light output signals combined. This results in greater phase and frequency coherency and narrower and reduced amplitude sidelobes. Preferably, not more than two lasers are longitudinally aligned along the same axis for still greater coherency compared with adding the light output signals of more than two longitudinally aligned lasers. The lasers can be of the DH-LOC type or of the QW type.

  5. Effect of Solventless Bore Cleaning Device (SBCD) on Surface Finish and Contamination Transport in the M256 Gun Barrel

    DTIC Science & Technology

    2006-09-01

    min. The brush itself is made from ceramic (silicon carbide) impregnated organic resin matrix spheres or strands which abrade away, along with the...Vacuum fixture designed to remove abraded brush and bore surface residue during cleaning...fixture designed to remove abraded brush and bore surface residue during cleaning. 2. Post-Cleaned SBCD Surface Finish Though the surface finish

  6. 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.

  7. 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.

  8. Potential use of copper as a hygienic surface; problems associated with cumulative soiling and cleaning.

    PubMed

    Airey, P; Verran, J

    2007-11-01

    It has been suggested that antibacterial copper could be used in place of stainless steel to help reduce the occurrence of hospital-acquired infections. The antibacterial activity of copper has been clearly demonstrated when using cell suspensions held in prolonged contact with copper or copper alloys. The aim of this study was to evaluate the antimicrobial properties of copper in comparison with stainless steel in a generally dry environment. Three stainless steels of varying surface finish and polished copper were soiled with Staphylococcus aureus suspended in a protein-based organic soil (bovine serum album), dried rapidly, and then incubated for 24 h. Surfaces were then wiped clean using a standardised wiping procedure with two cleaning agents recommended by UK National Health Service guidelines. This soiling/cleaning procedure was carried out daily over five days. After each cleaning cycle the amount of residual soil and live cells was assessed using direct epifluorescence microscopy. All materials were easily cleaned after the first soiling episode but a build-up of cells and soil was observed on the copper surfaces after several cleaning/wiping cycles. Stainless steel remained highly cleanable. Accumulation of material on copper is presumably due to the high reactivity of copper, resulting in surface conditioning. This phenomenon will affect subsequent cleaning, aesthetic properties and possibly antibacterial performance. It is important to select the appropriate cleaning/disinfecting protocols for selected surfaces.

  9. Laser Surface Treatment of Sintered Alumina

    NASA Astrophysics Data System (ADS)

    Hagemann, R.; Noelke, C.; Kaierle, S.; Wesling, V.

    Sintered alumina ceramics are used as refractory materials for industrial aluminum furnaces. In this environment the ceramic surface is in permanent contact with molten aluminum resulting in deposition of oxidic material on its surface. Consequently, a lower volume capacity as well as thermal efficiency of the furnaces follows. To reduce oxidic adherence of the ceramic material, two laser-based surface treatment processes were investigated: a powder- based single-step laser cladding and a laser surface remelting. Main objective is to achieve an improved surface quality of the ceramic material considering the industrial requirements as a high process speed.

  10. Bioinspired Surface for Low Drag, Self-Cleaning, and Antifouling: Shark Skin, Butterfly and Rice Leaf Effects

    NASA Astrophysics Data System (ADS)

    Bixler, Gregroy D.

    In this thesis, first presented is an overview of inorganic-fouling and biofouling which is generally undesirable for many medical, marine, and industrial applications. A survey of nature's flora and fauna are studied in order to discover new antifouling methods that could be mimicked for engineering applications. New antifouling methods will presumably incorporate a combination of physical and chemical controls. Presented are mechanisms and experimental results focusing on laminar and turbulent drag reducing shark skin inspired riblet surfaces. This includes new laser etched and riblet film samples for closed channel drag using water, oil, and air as well as in wind tunnel. Also presented are mechanisms and experimental results focusing on the newly discovered rice and butterfly wing effect surfaces. Morphology, drag, self-cleaning, contact angle, and contact angle hysteresis data are presented to understand the role of sample geometrical dimensions, wettability, viscosity, and velocity. Hierarchical liquid repellent coatings combining nano- and micro-sized features and particles are utilized to recreate or combine various effects. Such surfaces have been fabricated with photolithography, soft lithography, hot embossing, and coating techniques. Discussion is provided along with new 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 medical, marine, and industrial applications.

  11. 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.

  12. Failure of Cleaning Verification in Pharmaceutical Industry Due to Uncleanliness of Stainless Steel Surface.

    PubMed

    Haidar Ahmad, Imad A; Blasko, Andrei

    2017-08-11

    The aim of this work is to identify the parameters that affect the recovery of pharmaceutical residues from the surface of stainless steel coupons. A series of factors were assessed, including drug product spike levels, spiking procedure, drug-excipient ratios, analyst-to-analyst variability, intraday variability, and cleaning procedure of the coupons. The lack of a well-defined procedure that consistently cleaned the coupon surface was identified as the major contributor to low and variable recoveries. Assessment of cleaning the surface of the coupons with clean-in-place solutions (CIP) gave high recovery (>90%) and reproducible results (Srel≤4%) regardless of the conditions that were assessed previously. The approach was successfully applied for cleaning verification of small molecules (MW <1,000 Da) as well as large biomolecules (MW up to 50,000 Da).

  13. 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…

  14. 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…

  15. The use of the Karl sub-scale laser for Raman beam clean-up experiments

    NASA Astrophysics Data System (ADS)

    Dudas, Alan J.; Burris, Harris R.

    1987-03-01

    The two X-ray preionized discharge pumped front end lasers for the Raman Beam Clean-up Experiment (LARBC) have been examined both optically and electrically in an effort to increase the optical and temporal quality of the injection locked beam produced. The KARL subscale has been successfully injection locked by the front end lasers and preliminary studies of the stability of the injection locking begun. An isolator system has been designed and constructed to prevent damage to system optics from energy moving the wrong way in the system. A gas processing system was tested to remove contaminants in the laser gas. Additional units have been purchased for use on all lasers in the system. Diagnostics for the experiment will be coordinated through the WP3202 digitizing system.

  16. Effects of Nd:YAG (532 nm) laser radiation on `clean' cotton

    NASA Astrophysics Data System (ADS)

    Bloisi, F.; Vicari, L.; Barone, A. C.; Martuscelli, E.; Gentile, G.; Polcaro, C.

    The use of pulsed laser radiation in order to remove small particles from a substrate has gained a growing interest in the last decade, finding applications in several fields ranging from the microcircuits industry to cultural heritage restoration and conservation. The application of such a technique requires the knowledge of the correct laser irradiation parameters to be used in order to obtain a desired result avoiding substrate damage. In this paper we have studied the effect of frequency-doubled (532 nm) Nd:YAG laser radiation on clean cotton samples. We have observed that `yellowing' is present even at low fluences. This suggests that less invasive laser assisted particle removal techniques, some of which have already been proposed by different authors, must be considered.

  17. Method for Cleaning Laser-Drilled Holes on Printed Wiring Boards by Plasma Treatment

    NASA Astrophysics Data System (ADS)

    Hirogaki, Toshiki; Aoyama, Eiichi; Minagi, Ryu; Ogawa, Keiji; Katayama, Tsutao; Matsuoka, Takashi; Inoue, Hisahiro

    We propose a new method for cleaning blind via holes after laser drilling of PWBs using oxygen plasma treatment. This report dealt with three kinds of PWB materials: epoxy resin and two kinds of aramid fiber reinforced plastics (AFRP: Technora or Kevlar fiber reinforcement). We observed the drilled holes after plasma treatment using both an optical and a scanning electric microscope (SEM). It was confirmed that adequate etching took place in the drilled holes by plasma treatment. We also compared the hole wall and hole bottom after plasma treatment with ones after chemical etching. It was clear that there was no damage to the aramid fiber tip on the hole wall, and that a smooth roughness of the hole wall was obtained by means of plasma treatment. As a result, we demonstrated that the plasma treatment is effective in cleaning the laser drilled holes of PWBs.

  18. Crude Oil Remote Sensing, Characterization and Cleaning with ContinuousWave and Pulsed Lasers

    DTIC Science & Technology

    2015-01-23

    identification, and characterization of crude oil . These methods enable the three-dimensional characterization of oil spills that is important for... oil spills that is important for practical applications. Combined methods of CFP and HILI are described in the frame of coherent superposition of...cleaning methods of oil spills cause damage to the environment and pose a risk to human health,.. Oil removal/containment by Lasers offers advantages

  19. 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.

  20. Femtosecond laser-induced surface wettability modification of polystyrene surface

    NASA Astrophysics Data System (ADS)

    Wang, Bing; Wang, XinCai; Zheng, HongYu; Lam, YeeCheong

    2016-12-01

    In this paper, we demonstrated a simple method to create either a hydrophilic or hydrophobic surface. With femtosecond laser irradiation at different laser parameters, the water contact angle (WCA) on polystyrene's surface can be modified to either 12.7° or 156.2° from its original WCA of 88.2°. With properly spaced micro-pits created, the surface became hydrophilic probably due to the spread of the water droplets into the micro-pits. While with properly spaced micro-grooves created, the surface became rough and more hydrophobic. We investigated the effect of laser parameters on WCAs and analyzed the laser-treated surface roughness, profiles and chemical bonds by surface profilometer, scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). For the laser-treated surface with low roughness, the polar (such as C—O, C=O, and O—C=O bonds) and non-polar (such as C—C or C—H bonds) groups were found to be responsible for the wettability changes. While for a rough surface, the surface roughness or the surface topography structure played a more significant role in the changes of the surface WCA. The mechanisms involved in the laser surface wettability modification process were discussed.

  1. 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

    ... 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 Act... environmental review of Appalachian surface coal mining operations under the Clean Water Act,...

  2. Surface changes of implants after laser irradiation

    NASA Astrophysics Data System (ADS)

    Rechmann, Peter; Sadegh, Hamid M. M.; Goldin, Dan S.; Hennig, Thomas

    1999-05-01

    Periimplantitis is one of the major factors for the loss of dental implants. Due to the minor defense ability of the tissue surrounding the implant compared to natural teeth treatment of periimplantitis in the early stage is very important. Reducing bacteria with a laser might be the most successful step in therapy of periimplantitis. Aim of the study was to observe changes in surface morphology of seven different implants after irradiation with three different lasers. Two kinds of flat round samles were prepared by the manufacturers either identical to the body surface or to the cervical area of the corresponding implants. The samples were irradiated using different power settings. The lasers used were a CO2 laser (Uni Laser 450P, ASAH Medico Denmark; fiber guided, wavelength 10.6 μm, max. average power 8.3 W, "soft-pulse" and cw) an Er:YAG laser (KaVo Key Laser II, wavelength 2.94 μm, pulse duration 250-500μs, pulse energy 60-500 mJ, pulse repetition rate 1-15 Hz, focus diameter 620 μm, air-water cooling; Biberach, Germany; a frequency doubled Alexandrite laser (laboratory prototype, q-switched, fiber guided, wavelength 377 nm, pulse duration 1 μs, pulse repetition rate 30 Hz, water cooling). After irradiation the implant surfaces were investigated with a Scanning Electron Microscope. Ablation thresholds were determined. After CO2 laser irradiation no changes in surface morphology were observed whereas using the pulsed Er:YAG laser or frequency doubled Alexandrite laser even at low energies loss of integrity or melting of the surface was observed. The changes in surface morphology seem to depend very strongly on the type of surface coating.

  3. 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.

  4. Excimer laser surface processing of titanium

    SciTech Connect

    Jervis, T.R.; Hubbard, K.M.; Zocco, T.G.; Foster, L.; Nastasi, M.; Tesmer, J.R.

    1993-05-01

    We have examined the effect of laser surface processing of Ti alloys using pulsed excimer laser light at 248 nm. Thermal transformations of the surface are accomplished by heating the surface and rapid cooling. Alloying and formation of compounds can be obtained by melting and mixing surface layers into the material and by gas alloying. Multiple melting-resolidification cycles result in the inter-diffusion of surface layers in the liquid state and the diffusion of gas species into the material. The effect of alloying from both solid and gas sources and the effects of thermal transformations on the microstructure and surface hardness properties of these alloys will be examined.

  5. Excimer laser surface processing of titanium

    SciTech Connect

    Jervis, T.R.; Hubbard, K.M.; Zocco, T.G.; Foster, L.; Nastasi, M.; Tesmer, J.R.

    1993-01-01

    We have examined the effect of laser surface processing of Ti alloys using pulsed excimer laser light at 248 nm. Thermal transformations of the surface are accomplished by heating the surface and rapid cooling. Alloying and formation of compounds can be obtained by melting and mixing surface layers into the material and by gas alloying. Multiple melting-resolidification cycles result in the inter-diffusion of surface layers in the liquid state and the diffusion of gas species into the material. The effect of alloying from both solid and gas sources and the effects of thermal transformations on the microstructure and surface hardness properties of these alloys will be examined.

  6. 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

  7. The effect of surface cleaning on quantum efficiency in AlGaN photocathode

    NASA Astrophysics Data System (ADS)

    Hao, Guanghui; Zhang, Yijun; Jin, Muchun; Feng, Cheng; Chen, Xinlong; Chang, Benkang

    2015-01-01

    To improve the quantum efficiency of AlGaN photocathode, various surfaces cleaning techniques for the removal of alumina and carbon from AlGaN photocathode surface were investigated. The atomic compositions of AlGaN photocathode structure and surface were measured by the X-ray photoelectron spectroscopy and Ar+ ion sputtering. It is found that the boiling KOH solution and the mixture of sulfuric acid and hydrogen peroxide, coupled with the thermal cleaning at 850 °C can effectively remove the alumina and carbon from the AlGaN photocathode surface. The quantum efficiency of AlGaN photocathode is improved to 35.1% at 240 nm, an increase of 50% over the AlGaN photocathode chemically cleaned by only the mixed solution of sulfuric acid and hydrogen peroxide and thermally cleaned at 710 °C.

  8. 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

  9. Chemical cleaning of metal surfaces in vacuum systems by exposure to reactive gases

    SciTech Connect

    Grunze, M.; Ruppender, H.; Elshazly, O.

    1988-05-01

    Chemical surface cleaning procedures for metals using oxidation/reduction cycles by exposure to oxidizing (O/sub 2/, NO) and reducing (H/sub 2/, NH/sub 3/ ) gases are summarized and an update of the original compilation for chemical cleaning procedures published by Musket et al. (Appl. Surf. Sci. 10, 143 (1982)) is given. Examples discussed in this paper are cleaning procedures for iron, nickel, palladium, copper, and silver surfaces. We also present data on the reduction of gaseous contaminants in a stainless-steel UHV system by flowing nitric oxide through the system during bakeout.

  10. 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.

  11. 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.

  12. Air powder abrasive treatment as an implant surface cleaning method: a literature review.

    PubMed

    Tastepe, Ceylin S; van Waas, Rien; Liu, Yuelian; Wismeijer, Daniel

    2012-01-01

    To evaluate the air powder abrasive treatment as an implant surface cleaning method for peri-implantitis based on the existing literature. A PubMed search was conducted to find articles that reported on air powder abrasive treatment as an implant surface cleaning method for peri-implantitis. The studies evaluated cleaning efficiency and surface change as a result of the method. Furthermore, cell response toward the air powder abrasive-treated discs, reosseointegration, and clinical outcome after treatment is also reported. The PubMed search resulted in 27 articles meeting the inclusion criteria. In vitro cleaning efficiency of the method is reported to be high. The method resulted in minor surface changes on titanium specimens. Although the air powder abrasive-treated specimens showed sufficient levels of cell attachment and cell viability, the cell response decreased compared with sterile discs. Considerable reosseointegration between 39% and 46% and improved clinical parameters were reported after treatment when applied in combination with surgical treatment. The results of the treatment are influenced by the powder type used, the application time, and whether powder was applied surgically or nonsurgically. The in vivo data on air powder abrasive treatment as an implant surface cleaning method is not sufficient to draw definitive conclusions. However, in vitro results allow the clinician to consider the method as a promising option for implant surface cleaning in peri-implantitis treatment.

  13. 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.

  14. 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.

  15. Laser reflections from relatively flat specular surfaces.

    PubMed

    Marshall, W J

    1989-05-01

    A major element in laser range control procedures has been the control of stray reflections from glass reflectors which may be near the laser target. These hazardous reflections have been thought to extend as far as the direct beam for near grazing angles of incidence. Modern military laser rangefinders and designators can be hazardous to the unaided eye to distances of 10 km or even greater. For this reason, many square kilometers of laser range area have been necessary to conduct laser tests when flat specular reflectors may be present on targets. Fortunately, sophisticated pointing systems have been developed with these laser systems to ensure that the direct beam is confined to the immediate target area. In most cases, flat specular reflectors also have been eliminated from the immediate target area. In some instances, however, specular reflectors still exist near or on laser targets. For these special cases, a more definitive mathematical treatment of hazardous laser reflections is desired. The divergence of a laser beam which has been reflected from a flat specular surface is dependent on the size of the reflector, the divergence of the laser creating the reflection, and the curvature of the reflecting surface. It can be shown mathematically that the curvature of even an optical flat, a reference surface used to compare the flatness of other surfaces, will produce a significant additional beam spread, thereby reducing the hazards of reflected beams. The natural curvature of plate glass or window glass is much greater, reducing the hazards even further. The extent of the hazards for reflections of various types of lasers and reflecting surfaces is discussed.

  16. 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).

  17. 40 CFR 761.369 - Pre-cleaning the surface.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... CONTROL ACT POLYCHLORINATED BIPHENYLS (PCBs) MANUFACTURING, PROCESSING, DISTRIBUTION IN COMMERCE, AND USE... the entire surface with absorbent paper or cloth until no liquid is visible on the surface....

  18. 40 CFR 761.369 - Pre-cleaning the surface.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... CONTROL ACT POLYCHLORINATED BIPHENYLS (PCBs) MANUFACTURING, PROCESSING, DISTRIBUTION IN COMMERCE, AND USE... the entire surface with absorbent paper or cloth until no liquid is visible on the surface....

  19. The effect of chemical cleaning on surface roughness of steam generator tubes

    SciTech Connect

    Guzonas, D.A.; Semmler, J.

    1998-12-31

    The effect of chemical cleaning using an Electric Power Research Institute-Steam Generator Owners Group (EPRI-SGOG) iron removal solvent on the surface roughness of the secondary side of fouled and unfouled Alloy 800 steam generator tubes was characterized using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). The latter technique was used to quantify the surface roughness of the tubes before and after chemical cleaning. The surface roughness as a function of exposure time to the iron removal solvent was determined. It was found that the surface roughness of the fouled tube and the unfouled tube was slightly increased by chemical cleaning. The degree of roughening for the unfouled tube paralleled the corrosion of the tube surface. The surface roughness changes for the fouled tube indicated an isotropic dissolution of the oxide.

  20. Laser surface treatment of pre-prepared Rene 41 surface

    NASA Astrophysics Data System (ADS)

    Yilbas, B. S.; Akhtar, S.; Karatas, C.

    2012-11-01

    Laser controlled melting of pre-prepared Rene 41 surface is carried out. A carbon film composing of uniformly distributed 5% TiC carbide particles is formed at the surface prior to laser treatment process. The carbon film provides increased absorption of the incident radiation and facilitates embedding of TiC particles at the surface region of the workpiece during the treatment process. Nitrogen at high pressure is used as assisting gas during the controlled melting. It is found that laser treated layer extents 40 μm below the surface with almost uniform thickness. Fine grains and ultra-short dendrites are formed at the surface region of the laser treated layer. Partially dissolved TiC particles and γ, γ' and γ'N phases are observed in the treated layer.

  1. Surface ozone exposures measured at clean locations around the world.

    PubMed

    Lefohn, A S; Krupa, S V; Winstanley, D

    1990-01-01

    For assessing the effects of air pollution on vegetation, some researchers have used control chambers as the basis of comparison between crops and trees grown in contemporary polluted rural locations and those grown in a clean environment. There has been some concern whether the arbitrary ozone level of 0.025 ppm and below, often used in charcoal-filtration chambers to simulate the natural background concentration of ozone, is appropriate. Because of the many complex and man-made factors that influence ozone levels, it is difficult to determine natural background. To identify a range of ozone exposures that occur at 'clean' sites, we have calculated ozone exposures observed at a number of 'clean' monitoring sites located in the United States and Canada. We do not claim that these sites are totally free from human influence, but rather than the ozone concentrations observed at these 'clean' sites may be appropriate for use by vegetation researchers in control chambers as pragmatic and defensible surrogates for natural background. For comparison, we have also calculated ozone exposures observed at four 'clean' remote sites in the Northern and Southern Hemispheres and at two remote sites (Whiteface Mountain, NY and Hohenpeissenberg, FRG) that are considered to be more polluted. Exposure indices relevant for describing the relationship between ozone and vegetation effects were applied. For studying the effects of ozone on vegetation, the higher concentrations are of interest. The sigmoidally-weighted index appeared to best separate those sites that experienced frequent high concentration exposures from those that experienced few high concentrations. Although there was a consistent seasonal pattern for the National Oceanic and Atmospheric Administration (NOAA) Geophysical Monitoring for Climate Change (GMCC) sites indicating a winter/spring maximum, this was not the case for the other remote sites. Some sites in the continental United States and southern Canada

  2. A modified ATP benchmark for evaluating the cleaning of some hospital environmental surfaces.

    PubMed

    Lewis, T; Griffith, C; Gallo, M; Weinbren, M

    2008-06-01

    Hospital cleaning continues to attract patient, media and political attention. In the UK it is still primarily assessed via visual inspection, which can be misleading. Calls have therefore been made for a more objective approach to assessing surface cleanliness. To improve the management of hospital cleaning the use of adenosine triphosphate (ATP) in combination with microbiological analysis has been proposed, with a general ATP benchmark value of 500 relative light units (RLU) for one combination of test and equipment. In this study, the same test combination was used to assess cleaning effectiveness in a 1300-bed teaching hospital after routine and modified cleaning protocols. Based upon the ATP results a revised stricter pass/fail benchmark of 250 RLU is proposed for the range of surfaces used in this study. This was routinely achieved using modified best practice cleaning procedures which also gave reduced surface counts with, for example, aerobic colony counts reduced from >100 to <2.5 cfu/cm(2), and counts of Staphylococcus aureus reduced from up to 2.5 to <1 cfu/cm(2) (95% of the time). Benchmarking is linked to incremental quality improvements and both the original suggestion of 500 RLU and the revised figure of 250 RLU can be used by hospitals as part of this process. They can also be used in the assessment of novel cleaning methods, such as steam cleaning and microfibre cloths, which have potential use in the National Health Service.

  3. 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

  4. 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.

  5. Cleaning Compound Efficiency; Test Method for Aircraft Surface Cleaners

    DTIC Science & Technology

    1983-11-01

    Coolanol 25R DO , 1473 COITION * F I II NOV UCA S O ED S/N 0102.LF.01446601 UNCLASSIFIED SE$CURITY CLAhSIFICATION O THNIl PAGE (Whmen0 Dae nt*,64) NADC-84...MIL-L-23699> MIL-H-83282 (least tenacious, highest soil removal results). Finally, cleaning efficiencies were also measured using Monsanto’s Coolanol ...soil removal range tend to exhibit limited variability, the Coolanol results were not included in variance calculations in order to better judge the

  6. Metal surface nitriding by laser induced plasma

    NASA Astrophysics Data System (ADS)

    Thomann, A. L.; Boulmer-Leborgne, C.; Andreazza-Vignolle, C.; Andreazza, P.; Hermann, J.; Blondiaux, G.

    1996-10-01

    We study a nitriding technique of metals by means of laser induced plasma. The synthesized layers are composed of a nitrogen concentration gradient over several μm depth, and are expected to be useful for tribological applications with no adhesion problem. The nitriding method is tested on the synthesis of titanium nitride which is a well-known compound, obtained at present by many deposition and diffusion techniques. In the method of interest, a laser beam is focused on a titanium target in a nitrogen atmosphere, leading to the creation of a plasma over the metal surface. In order to understand the layer formation, it is necessary to characterize the plasma as well as the surface that it has been in contact with. Progressive nitrogen incorporation in the titanium lattice and TiN synthesis are studied by characterizing samples prepared with increasing laser shot number (100-4000). The role of the laser wavelength is also inspected by comparing layers obtained with two kinds of pulsed lasers: a transversal-excited-atmospheric-pressure-CO2 laser (λ=10.6 μm) and a XeCl excimer laser (λ=308 nm). Simulations of the target temperature rise under laser irradiation are performed, which evidence differences in the initial laser/material interaction (material heated thickness, heating time duration, etc.) depending on the laser features (wavelength and pulse time duration). Results from plasma characterization also point out that the plasma composition and propagation mode depend on the laser wavelength. Correlation of these results with those obtained from layer analyses shows at first the important role played by the plasma in the nitrogen incorporation. Its presence is necessary and allows N2 dissociation and a better energy coupling with the target. Second, it appears that the nitrogen diffusion governs the nitriding process. The study of the metal nitriding efficiency, depending on the laser used, allows us to explain the differences observed in the layer features

  7. 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.

  8. Cleaning and heat-treatment effects on unalloyed titanium implant surfaces.

    PubMed

    Kilpadi, D V; Lemons, J E; Liu, J; Raikar, G N; Weimer, J J; Vohra, Y

    2000-01-01

    This study tested the following hypotheses: (1) acid-cleaned and passivated unalloyed titanium implants have higher surface energies (which are considered desirable for bone implants) than ethanol-cleaned titanium; (2) higher temperatures of heat treatment of unalloyed titanium result in higher surface energies; and (3) these changes can be related to changes in surface composition and roughness. Thus, unalloyed titanium specimens were either acid-cleaned and passivated (CP) or ethanol-cleaned (Et). Each set was then divided into 3 groups and heat-treated for 1 hour at 316 degrees C (600 degrees F), 427 degrees C (800 degrees F), and 538 degrees C (1,000 degrees F), respectively. Surface roughness values for each of these groups were determined using atomic force microscopy, while surface compositions were determined using Auger electron, x-ray photoelectron, and Raman spectroscopic techniques. Surface energies were estimated using a 2-liquid geometric mean technique and correlated with surface roughness, elemental composition, and elemental thickness. The CP surfaces were slightly rougher than the Et specimens, which had greater oxide thickness and hydrocarbon presence. The surface oxides were composed of TiO2, Ti2O3, and possibly titanium peroxide; those heat-treated at 427 degrees C or above were crystalline. The CP specimens had carbonaceous coverage that was of a different composition from that on Et specimens. The CP specimens had significantly higher surface energies, which showed statistically significant correlations with oxide thickness and carbonaceous presence. In conclusion, ethanol cleaning of unalloyed titanium dental implants may not provide optimal surface properties when compared to cleaning with phosphoric acid followed by nitric acid passivation.

  9. 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.

  10. 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

    2015-03-06

    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. Copyright © 2015, American Association for the Advancement of Science.

  11. Research on chemical cleaning technology for super-smooth surface of fused silica substrate

    NASA Astrophysics Data System (ADS)

    Jiao, Lingyan; Jin, Yuzhu; Ji, Yiqin; Tong, Yi; Wang, Fang; Liu, Tao; Wang, Lishuan

    2010-10-01

    A chemical technology for cleaning super-smooth surface, based on wet method, is put forward in order to solve the problems including that the dirt existing on the surface of optical components is difficult to remove, and the system used to estimate the surface quality is hard to establish. Firstly, in this paper, all kinds of dirt existing on optical surface and their adsorption mechanism are discussed. Secondly, a cleaning route has been designed. Thirdly, all the reagents in use are prepared and their decontamination capabilities are described. Finally, the cleaned optical components are tested. The result shows that the surface cleanliness is high, the defect density is no more than 0.7/mm2 within a certain area, and the scattering loss is no more than 20ppm.

  12. 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.

  13. 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.

  14. Effect of laser treatment on the surface of copper alloys

    NASA Astrophysics Data System (ADS)

    Garbacz, Halina; Fortuna-Zalesna, Elzbieta; Marczak, Jan; Koss, Andrzej; Zatorska, Anna; Zukowska, Grazyna Z.; Onyszczuk, Tomasz; Kurzydlowski, Krzysztof J.

    2011-06-01

    The paper presents the results of laser cleaning of the archaeological metal objects using two time widths of pulsed laser radiation, which are around 150 μs and around 120 ns. Two archaeological objects made of copper alloys were studied: a bow and a ring. Both objects came from a cemetery which is located in the garden complex of Wilanow Palace in Warsaw and are dated from XII to XIII century. The bow and bronze ring had ornamental longitudinal grooving and were part of burial jewellery. The materials of which these artefacts were made of, as well as corrosion products on these objects, were studied by using a variety of analytical techniques. The phase composition of the corrosion layers was determined by using Raman spectroscopy. The surface topography as well as the chemical composition of the deposits and cleaned surfaces were investigated. The samples were examined using scanning electron microscopes equipped with EDS. The investigations included observations in SE and BSE modes and point analyses of the chemical composition by EDS.

  15. Possibilities of a metal surface radioactive decontamination using a pulsed CO2 laser

    NASA Astrophysics Data System (ADS)

    Milijanic, Scepan S.; Stjepanovic, Natasa N.; Trtica, Milan S.

    2000-01-01

    There is a growing interest in the laser radioactive decontamination of metal surfaces. It offers advantages over conventional methods: improved safety, reduction of secondary waste, reduced waste volume, acceptable cost. A main mechanism of cleaning in by lasers is ablation. In this work a pulsed TEA CO2 laser was used for surface cleaning, primarily in order to demonstrate that the ablation from metal surfaces with this laser is possible even with relatively low pulse energies, and secondary, that it could be competitive with other lasers because of much higher energy efficiencies. The laser pulse contains two parts, one strong and shot peak at the beginning, followed with a tail. The beam was focused onto a contaminated surface with a KBr lens. The surface was contaminated with 137Cs. Three different metals were used: stainless steel, copper and aluminum. The evaporated material was pumped out in air atmosphere and transferred to a filter. Presence of the activity on the filter was proved by a germanium detector-multichannel analyzer. Activity levels were measured by a GM counter. Calculated decontamination factors as well as collection factors have shown that ablation takes place with relatively high efficiency of decontamination. This investigation suggests that decontamination using the CO2 laser should be seriously considered.

  16. 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.

  17. Characterization, optimization and surface physics aspects of in situ plasma mirror cleaning.

    PubMed

    Pellegrin, Eric; Sics, Igors; Reyes-Herrera, Juan; Perez Sempere, Carlos; Lopez Alcolea, Juan Josep; Langlois, Michel; Fernandez Rodriguez, Jose; Carlino, Vincent

    2014-03-01

    Although the graphitic carbon contamination of synchrotron beamline optics has been an obvious problem for several decades, the basic mechanisms underlying the contamination process as well as the cleaning/remediation strategies are not understood and the corresponding cleaning procedures are still under development. In this study an analysis of remediation strategies all based on in situ low-pressure RF plasma cleaning approaches is reported, including a quantitative determination of the optimum process parameters and their influence on the chemistry as well as the morphology of optical test surfaces. It appears that optimum results are obtained for a specific pressure range as well as for specific combinations of the plasma feedstock gases, the latter depending on the chemical aspects of the optical surfaces to be cleaned.

  18. 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.

  19. 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.

  20. 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.

  1. Laser ignition of plasma off aluminum surfaces

    NASA Astrophysics Data System (ADS)

    Weyl, G.; Pirri, A.; Root, R.

    1980-07-01

    The prompt initiation of a plasma above metal surfaces irradiated by a CO2 laser pulse in the intensities range one million to one billion W per sq cm is modelled. The initiation mechanism is assumed to be the vaporization of flakes or surface defects that are thermally insulated from the bulk surface, followed by laser induced breakdown in the vapor. The fluid dynamics of the expansion in an air background is modelled in the 1 dimensional and 3 dimensional regimes. Breakdown of the vapor due to inverse bremsstrahlung absorption of the laser radiation is calculated specifically for aluminum by use of a Boltzmann code. Results are presented in the form of a map of breakdown time versus incident laser flux and compared with available experimental data.

  2. Laser surface conditioning of semimetallic friction materials

    SciTech Connect

    Patten, D.T.

    1986-01-01

    Surface conditioning is one way of reducing the duration and magnitude of the initial transients occurring in friction materials. In developing a laser searing system for semimetallic materials the changes occurring on the surface were characterized as a function of the power density. Excessive power melted the surface of the lining and produced an undesirable microstructure, while too little power did not produce the changes desired. The changes produced by laser searing were found to be similar to the changes produced by other types of surface conditioning. The friction and wear performance was studied for linings seared with different power densities. Laser searing primarily increased the low speed, low temperature, pre-burnish friction level. The amount of increase was proportional to the amount of searing. After burnishing the searing did not effect the friction level of the lining. Excessive power densities produced undesirable surface microstructures and persistent rotor scoring.

  3. 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.

  4. Surface photochemistry of phosgene on clean and iodine-covered Ag(111)

    SciTech Connect

    Zhou, X.L.; White, J.M. )

    1990-03-22

    The photochemistry of phosgene (Cl{sub 2}CO) on clean and partially iodine covered Ag(111) has been studied. Cl{sub 2}CO adsorbed on Ag(111) at 100 K desorbs molecularly with no detectable thermal decomposition. On clean Ag(111) K, UV photolysis occurs readily for both submonolayer and multilayer coverages. The photolysis products are chlorine, which remains on the surface, and CO, which desorbs during irradiation. There is no detectable photodesorption of molecular Cl{sub 2}CO.

  5. Optimized Cleaning Method for Producing Device Quality InP(100) Surfaces

    SciTech Connect

    Sun, Y.

    2005-02-07

    A very effective, two-step chemical etching method to produce clean InP(100) surfaces when combined with thermal annealing has been developed. The hydrogen peroxide/sulfuric acid based solutions, which are successfully used to clean GaAs(100) surfaces, leave a significant amount of residual oxide on the InP surface which can not be removed by thermal annealing. Therefore, a second chemical etching step is needed to remove the oxide. We found that strong acid solutions with HCl or H{sub 2}SO{sub 4} are able to remove the surface oxide and leave the InP surface passivated with elemental P which is, in turn, terminated with H. This yields a hydrophobic surface and allows for lower temperatures to be used during annealing. We also determined that the effectiveness of oxide removal is strongly dependent on the concentration of the acid. Surfaces cleaned by HF solutions were also studied and result in a hydrophilic surface with F terminated surface In atoms. The chemical reactions leading to the differences in behavior between InP and GaAs are analyzed and the optimum cleaning method for InP is discussed.

  6. Study of Sn removal by surface wave plasma for source cleaning

    NASA Astrophysics Data System (ADS)

    Panici, Gianluca; Qerimi, Dren; Ruzic, David N.

    2017-03-01

    A hydrogen plasma cleaning technique to clean Sn off of EUV sources is studied in detail. The cleaning process uses hydrogen radicals (formed in the hydrogen plasma) to interact with Sn-coated surfaces, forming SnH4 and being pumped away. This technique has been used to clean a 300mm-diameter stainless steel dummy collector optic, and EUV reflectivity of multilayer mirror samples was restored after cleaning Sn from them, validating the potential of this technology. A concern for plasma based methods is the implantation of high energy hydrogen ions into the MLM, reducing reflectivity and possibly blistering. With a surface wave plasma (SWP) this concern is alleviated somewhat because of lower ion energies. Surface wave plasmas have lower electron temperatures than conventional sources in the range of 1 to 3 eV. In addition, SWP sources result in plasma densities on the order of 1011-12 cm-3, allowing for greater utilization of ion etch enhancement. Experiments measuring radical density and etch rate profiles have been conducted and the results from these measurements are presented. These will help demonstrate scalability of SWP cleaning techniques for use in EUV sources.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Efficacy of low-pressure foam cleaning compared to conventional cleaning methods in the removal of bacteria from surfaces associated with convenience food.

    PubMed

    Lambrechts, A A; Human, I S; Doughari, J H; Lues, J F R

    2014-09-01

    Food borne illnesses and food poisoning are cause for concern globally. The diseases are often caused by food contamination with pathogenic bacteria due largely to poor sanitary habits or storage conditions. Prevalence of some bacteria on cleaned and sanitised food contact surfaces from eight convenience food plants in Gauteng (South Africa) was investigated with the view to evaluate the efficacy of the cleaning methods used with such food contact surfaces. The microbial load of eight convenience food manufacturing plants was determined by sampling stainless steel food contact surfaces after they had been cleaned and sanitised at the end of a day's shift. Samples were analysed for Total Plate Count (TPC), Escherichia coli, Salmonella species, Staphylococcus aureus and Listeria species. Results showed that 59 % of the total areas sampled for TPC failed to comply with the legal requirements for surfaces, according to the Foodstuffs, Cosmetics and Disinfectants Act (< 100 cfu.cm(-2)). S. aureus and Salmonella were not detected, but Listeria was detected in 23 % and E. coli in 1.3 % of the samples. Fifty percent (50 %) of the plants applied conventional cleaning methods for cleaning and sanitation and 50 % used the low-pressure foam (LPF) method. There was significant difference (P ≤ 0.05) between the mean TPC values of the conventional cleaning method (14 358.82) compared to that of LPF method (2 386.51) but no significant difference (P > 0.05) in terms of Listeria species isolates obtained from both cleaning methods. The LPF method proved to be the superior cleaning option for lowering TPC counts. Regardless of cleaning method used, pathogens continued to flourish on various surfaces, including dry stainless steel, posing a contamination hazard for a considerable period depending on the contamination level and type of pathogen. Intensive training for proper chemical usage and strict procedural compliance among workers for efficient cleaning procedures is

  13. [Surface Cleaning and Disinfection in the Hospital. Improvement by Objective Monitoring and Intervention].

    PubMed

    Woltering, R; Hoffmann, G; Isermann, J; Heudorf, U

    2016-11-01

    Background and Objective: An assessment of cleaning and disinfection in hospitals by the use of objective surveillance and review of mandatory corrective measures was undertaken. Methods: A prospective examination of the cleaning and disinfection of surfaces scheduled for daily cleaning in 5 general care hospitals by use of an ultraviolet fluorescence targeting method (UVM) was performed, followed by structured educational and procedural interventions. The survey was conducted in hospital wards, operating theatres and intensive care units. Cleaning performance was measured by complete removal of UVM. Training courses and reinforced self-monitoring were implemented after the first evaluation. 6 months later, we repeated the assessment for confirmation of success. Results: The average cleaning performance was 34% (31/90) at base-line with significant differences between the 5 hospitals (11-67%). The best results were achieved in intensive care units (61%) and operating theatres (58%), the worst results in hospital wards (22%). The intervention significantly improved cleaning performance up to an average of 69% (65/94; +34.7%; 95% confidence interval (CI): 21.2-48.3; p<0.05), with differences between the hospitals (20-95%). The largest increase was achieved in hospital wards (+45%; CI 29.2-60.8; p<0.05). Improvements in operating theatres (+22.9%; CI 10.9-56.7) and intensive care units (+5.6%; CI 25.8-36.9) were statistically not significant. Conclusions: The monitoring of cleaning and disinfection of surfaces by fluorescence targeting is appropriate for evaluating hygiene regulations. An intervention can lead to a significant improvement of cleaning performance. As part of a strategy to improve infection control in hospitals, fluorescence targeting enables a simple inexpensive and effective surveillance of the cleaning performance and corrective measures. © Georg Thieme Verlag KG Stuttgart · New York.

  14. Portable Fiber Laser System and Method to Remove Pits and Cracks on Sensitized Surfaces of Aluminum Alloys

    DTIC Science & Technology

    2015-08-01

    and Cracks on Sensitized Surfaces of Aluminum Alloys Prepared for DEPARTMENT OF THE NAVY Office of Naval Research For the period July 1, 2015... Cracks on Sensitized Surfaces of Aluminum Alloys 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e...laser repair system integrated with the capabilities of surface cleaning, local heating, and peening using a single laser to remove pits and cracks in

  15. 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.

  16. Cleaning of niobium surface by plasma of diffuse discharge at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Tarasenko, V. F.; Erofeev, M. V.; Shulepov, M. A.; Ripenko, V. S.

    2017-07-01

    Elements composition of niobium surface before and after plasma treatment by runaway electron preionized diffuse discharge was investigated in atmospheric pressure nitrogen flow by means of an Auger electron spectroscopy. Surface characterizations obtained from Auger spectra show that plasma treatment by diffuse discharge after exposure of 120000 pulses provides ultrafine surface cleaning from carbon contamination. Moreover, the surface free energy of the treated specimens increased up to 3 times, that improve its adhesion property.

  17. The construction, fouling and enzymatic cleaning of a textile dye surface.

    PubMed

    Onaizi, Sagheer A; He, Lizhong; Middelberg, Anton P J

    2010-11-01

    The enzymatic cleaning of a rubisco protein stain bound onto Surface Plasmon Resonance (SPR) biosensor chips having a dye-bound upper layer is investigated. This novel method allowed, for the first time, a detailed kinetic study of rubisco cleanability (defined as fraction of adsorbed protein removed from a surface) from dyed surfaces (mimicking fabrics) at different enzyme concentrations. Analysis of kinetic data using an established mathematical model able to decouple enzyme transfer and reaction processes [Onaizi, He, Middelberg, Chem. Eng. Sci. 64 (2008) 3868] revealed a striking effect of dyeing on enzymatic cleaning performance. Specifically, the absolute rate constants for enzyme transfer to and from a dye-bound rubisco stain were significantly higher than reported previously for un-dyed surfaces. These increased transfer rates resulted in higher surface cleanability. Higher enzyme mobility (i.e., higher enzyme adsorption and desorption rates) at the liquid-dye interface was observed, consistent with previous suggestions that enzyme surface mobility is likely correlated with overall enzyme cleaning performance. Our results show that reaction engineering models of enzymatic action at surfaces may provide insight able to guide the design of better stain-resistant surfaces, and may also guide efforts to improve cleaning formulations.

  18. 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.

  19. 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.

  20. Extreme laser pulses for possible development of boron fusion power reactors for clean and lasting energy

    NASA Astrophysics Data System (ADS)

    Hora, H.; Eliezer, S.; Kirchhoff, G. J.; Korn, G.; Lalousis, P.; Miley, G. H.; Moustaizis, S.

    2017-05-01

    The nuclear reaction of hydrogen (protons) with the boron isotope 11 (HB11) is aneutronic avoiding the production of dangerous neutrons in contrast to any other fusion but it is extremely difficult at thermal equilibrium plasma conditions. There are alternative schemes without thermal equilibrium, e.g. the Tri Alpha reversed magnetic field (RMF) confinement and others, however, the only historical first measurements of HB11 fusion were with lasers interacting with high density plasmas using non-thermal direct conversion of laser energy into ultrahigh acceleration of plasma blocks to avoid the thermal problems. Combining these long studied mechanisms with recently measured ultrahigh magnetic fields for trapping the reacting plasma arrives at a very compact design of an environmentally clean reactor for profitable low cost energy using present technologies.

  1. Rough Structure of Electrodeposition as a Template for an Ultrarobust Self-Cleaning Surface.

    PubMed

    Qing, Yongquan; Hu, Chuanbo; Yang, Chuanning; An, Kai; Tang, Fawei; Tan, Junyang; Liu, Changsheng

    2017-05-17

    Superhydrophobic surfaces with self-cleaning properties have been developed based on roughness on the micro- and nanometer scales and low-energy surfaces. However, such surfaces are fragile and stop functioning when exposed to oil. Addressing these challenges, here we show an ultrarobust self-cleaning surface fabricated by a process of metal electrodeposition of a rough structure that is subsequently coated with fluorinated metal-oxide nanoparticles. Scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction were employed to characterize the surfaces. The micro- and nanoscale roughness jointly with the low surface energy imparted by the fluorinated nanoparticles yielded surfaces with water contact angle of 164.1° and a sliding angle of 3.2°. Most interestingly, the surface exhibits fascinating mechanical stability after finger-wipe, knife-scratch, sand abrasion, and sandpaper abrasion tests. It is found that the surface with superamphiphobic properties has excellent repellency toward common corrosive liquids and low-surface-energy substances. Amazingly, the surface exhibited excellent self-cleaning ability and remained intact even after its top layer was exposed to 50 abrasion cycles with sandpaper and oil contamination. It is believed that this simple, unique, and practical method can provide new approaches for effectively solving the stability issue of superhydrophobic surfaces and could extend to a variety of metallic materials.

  2. 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.

  3. Self-cleaning skin-like prosthetic polymer surfaces

    DOEpatents

    Simpson, John T [Clinton, TN; Ivanov, Ilia N [Knoxville, TN; Shibata, Jason [Manhattan Beach, CA

    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.

  4. Control of pyrite surface chemistry in physical coal cleaning

    SciTech Connect

    Luttrell, G.H.; Yoon, R.H.; Lagno, M.L.

    1991-01-01

    The removal of pyrite from coal by flotation or any other surface- based separation process is often hampered by the apparent hydrophobicity of the mineral. Microflotation tests and induction time measurements conducted under different conditions showed that the hydrophobicity of coal pyrite is due to superficial oxidation of the mineral surface. X-ray photoelectron spectroscopy (XPS) analysis of the oxidized pyrite samples suggests that the sulfur-rich surfaces formed during oxidation may be responsible for the hydrophobicity of both coal pyrite and mineral pyrite. Based on these findings, an oxidation mechanism is proposed in which metal polysulfides and iron oxides-hydroxides are produced. The floatability of both coal pyrite and mineral pyrite can be correlated with the atomic ration between these hydrophobic and hydrophilic species that are formed on the surface. 14 refs., 7 figs., 1 tab.

  5. 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.

  6. Surface Microbes in the Neonatal Intensive Care Unit: Changes with Routine Cleaning and over Time

    PubMed Central

    Bokulich, Nicholas A.; Mills, David A.

    2013-01-01

    Premature infants in neonatal intensive care units (NICUs) are highly susceptible to infection due to the immaturity of their immune systems, and nosocomial infections are a significant risk factor for death and poor neurodevelopmental outcome in this population. To investigate the impact of cleaning within a NICU, a high-throughput short-amplicon-sequencing approach was used to profile bacterial and fungal surface communities before and after cleaning. Intensive cleaning of surfaces in contact with neonates decreased the total bacterial load and the percentage of Streptococcus species with similar trends for total fungal load and Staphylococcus species; this may have clinical relevance since staphylococci and streptococci are the most common causes of nosocomial NICU infections. Surfaces generally had low levels of other taxa containing species that commonly cause nosocomial infections (e.g., Enterobacteriaceae) that were not significantly altered with cleaning. Several opportunistic yeasts were detected in the NICU environment, demonstrating that these NICU surfaces represent a potential vector for spreading fungal pathogens. These results underline the importance of routine cleaning as a means of managing the microbial ecosystem of NICUs and of future opportunities to minimize exposures of vulnerable neonates to potential pathogens and to use amplicon-sequencing tools for microbial surveillance and hygienic testing in hospital environments. PMID:23740726

  7. 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.

  8. Cleaning verification: Exploring the effect of the cleanliness of stainless steel surface on sample recovery.

    PubMed

    Haidar Ahmad, Imad A; Tam, James; Li, Xue; Duffield, William; Tarara, Thomas; Blasko, Andrei

    2017-02-05

    The parameters affecting the recovery of pharmaceutical residues from the surface of stainless steel coupons for quantitative cleaning verification method development have been studied, including active pharmaceutical ingredient (API) level, spiking procedure, API/excipient ratio, analyst-to-analyst variability, inter-day variability, and cleaning procedure of the coupons. The lack of a well-defined procedure that consistently cleaned coupon surface was identified as the major contributor to low and variable recoveries. Assessment of acid, base, and oxidant washes, as well as the order of treatment, showed that a base-water-acid-water-oxidizer-water wash procedure resulted in consistent, accurate spiked recovery (>90%) and reproducible results (Srel≤4%). By applying this cleaning procedure to the previously used coupons that failed the cleaning acceptance criteria, multiple analysts were able to obtain consistent recoveries from day-to-day for different APIs, and API/excipient ratios at various spike levels. We successfully applied our approach for cleaning verification of small molecules (MW<1000Da) as well as large biomolecules (MW up to 50,000Da). Method robustness was greatly influenced by the sample preparation procedure, especially for analyses using total organic carbon (TOC) determination. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Advanced Techniques for Improving Laser Optical Surfaces

    DTIC Science & Technology

    1975-03-01

    methanol and permitting drops of the suspensions to dry on cleaned glass slides. The slides were coated with .00 angstrom aluminum films and...surface to be replicated, improper coating of it. or nonuniform re- moval of the film can cause artifacts in the replica which are difficult to interpret...difficult to coat uniformly and so act as defect sites in thin film coatings on the etched pieces. A second series of damage experiments which was

  10. Surface modification of titanium membrane by chemical vapor deposition and its electrochemical self-cleaning

    NASA Astrophysics Data System (ADS)

    Li, X. W.; Li, J. X.; Gao, C. Y.; Chang, M.

    2011-10-01

    Membrane separation is applied widely in many fields, while concentration polarization and membrane fouling, limiting its promotion and application greatly, are the bottlenecks in membrane application. Among which, membrane fouling is irreversible, membrane must be periodically cleaned or even replaced to restore permeability. Membrane cleaning has become one of the key issues in membrane separation areas. Considering incomparable electrochemical advantages of boron-doped diamond (BDD) film electrode over conventional electrode, a new composite membrane Ti/BDD, made by depositing CVD (chemical vapor deposition) boron-doped diamond film on titanium(Ti) membrane to modify porous titanium surface, that can be cleaned electrochemically is proposed. Feasibility of its preparation and application is discussed in this paper. Results shows that based on the unique electrochemical properties of diamond, cleaning level of this composite Ti/BDD membrane is significantly increased, making membrane life and efficiency improved prominently.

  11. Avalanche boron fusion by laser picosecond block ignition with magnetic trapping for clean and economic reactor

    DOE PAGES

    Hora, H.; Korn, G.; Eliezer, S.; ...

    2016-10-11

    Measured highly elevated gains of proton–boron (HB11) fusion (Picciottoet al., Phys. Rev. X4, 031030 (2014)) confirmed the exceptional avalanche reaction process (Lalousiset al., Laser Part. Beams 32, 409 (2014); Horaet al., Laser Part. Beams33, 607 (2015)) for the combination of the non-thermal block ignition using ultrahigh intensity laser pulses of picoseconds duration. The ultrahigh accelerationabovemore » $$10^{20}~\\text{cm}~\\text{s}^{-2}$$ for plasma blocks was theoretically and numerically predicted since 1978 (Hora,Physics of Laser Driven Plasmas(Wiley, 1981), pp. 178 and 179) and measured (Sauerbrey, Phys. Plasmas3, 4712 (1996)) in exact agreement (Horaet al., Phys. Plasmas14, 072701 (2007)) when the dominating force was overcoming thermal processes. This is based on Maxwell’s stress tensor by the dielectric properties of plasma leading to the nonlinear (ponderomotive) force $$f_{\\text{NL}}$$ resulting in ultra-fast expanding plasma blocks by a dielectric explosion. Combining this with measured ultrahigh magnetic fields and the avalanche process opens an option for an environmentally absolute clean and economic boron fusion power reactor. Finally, this is supported also by other experiments with very high HB11 reactions under different conditions (Labauneet al., Nature Commun.4, 2506 (2013)).« less

  12. 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.

  13. Cleaning assessment of disinfectant cleaning wipes on an external surface of a medical device contaminated with artificial blood or Streptococcus pneumoniae.

    PubMed

    Gold, Kathryn M; Hitchins, Victoria M

    2013-10-01

    Improperly cleaned, disinfected, or sterilized reusable medical devices are a critical cause of health care-associated infections. More effective studies are required to address the improvement of cleaning and disinfection instructions, as well as selection of cleaning and disinfecting agents, for surfaces of reusable devices and equipment. Six commercially available disinfectant cleaning wipes were evaluated for their effectiveness to remove a coagulated blood test soil or Streptococcus pneumoniae bacteria from the surface of a reusable medical device. Liquid aliquots of the coagulated blood or bacteria were dried onto the surface of the device and removed with the wipes. Effectiveness of the wipes was assessed by 3 methods: residual protein debris by o-phthaldialdehyde analysis, bacterial survival by adenosine triphosphate measurement, and force required to remove the dried debris by force measurement. A sodium hypochlorite wipe was most effective in removing protein debris from the device surface. All tested wipes were equivalent in disinfecting bacterial contamination from the device surface. The active ingredient, wipe design, and wipe wetness are important factors to consider when selecting a disinfectant cleaning wipe. Additionally, achieving conditions that effectively clean, disinfect, and/or inactivate surface bacterial contamination is critical to preventing the spread of health care-associated infections. Published by Mosby, Inc.

  14. 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.

  15. In situ ion gun cleaning of surface adsorbates and its effect on electrostatic forces

    NASA Astrophysics Data System (ADS)

    Schafer, Robert; Xu, Jun; Mohideen, Umar

    2016-01-01

    To obtain precise measurements of the Casimir force, it is crucial to take into account the electrostatic interactions that exist between the two boundaries. Two otherwise grounded conductors will continue to have residual electrostatic effects from patch potentials existing on the surfaces. In this paper, we look at the effect of in situ cleaning of adsorbate patches, and the resultant effect on the net electrostatic potential difference between two surfaces. We find a significant reduction in the residual potential due to in situ Ar+ cleaning for the samples used.

  16. 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.

  17. 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.

  18. Removal and transfer of viruses on food contact surfaces by cleaning cloths.

    PubMed

    Gibson, Kristen E; Crandall, Philip G; Ricke, Steven C

    2012-05-01

    Contamination of food contact surfaces with pathogens is considered an important vehicle for the indirect transmission of food-borne diseases. Five different cleaning cloths were assessed for the ability to remove viruses from food contact surfaces (stainless steel surface and nonporous solid surface) and to transfer viruses back to these surfaces. Cleaning cloths evaluated include two different cellulose/cotton cloths, one microfiber cloth, one nonwoven cloth, and one cotton terry bar towel. Four viral surrogates (murine norovirus [MNV], feline calicivirus [FCV], bacteriophages PRD1 and MS2) were included. Removal of FCV from stainless steel was significantly greater (P ≤ 0.05) than that from nonporous solid surface, and overall removal of MNV from both surfaces was significantly less (P ≤ 0.05) than that of FCV and PRD1. Additionally, the terry towel removed significantly fewer total viruses (P ≤ 0.05) than the microfiber and one of the cotton/cellulose cloths. The cleaning cloth experiments were repeated with human norovirus. For transfer of viruses from cloth to surface, both cellulose/cotton cloths and microfiber transferred an average of 3.4 and 8.5 total PFU, respectively, to both surfaces, and the amounts transferred were significantly different (P ≤ 0.05) from those for the nonwoven cloth and terry towel (309 and 331 total PFU, respectively). There was no statistically significant difference (P > 0.05) in the amount of virus transfer between surfaces. These data indicate that while the cleaning cloths assessed here can remove viruses from surfaces, some cloths may also transfer a significant amount of viruses back to food contact surfaces.

  19. Removal and Transfer of Viruses on Food Contact Surfaces by Cleaning Cloths

    PubMed Central

    Crandall, Philip G.; Ricke, Steven C.

    2012-01-01

    Contamination of food contact surfaces with pathogens is considered an important vehicle for the indirect transmission of food-borne diseases. Five different cleaning cloths were assessed for the ability to remove viruses from food contact surfaces (stainless steel surface and nonporous solid surface) and to transfer viruses back to these surfaces. Cleaning cloths evaluated include two different cellulose/cotton cloths, one microfiber cloth, one nonwoven cloth, and one cotton terry bar towel. Four viral surrogates (murine norovirus [MNV], feline calicivirus [FCV], bacteriophages PRD1 and MS2) were included. Removal of FCV from stainless steel was significantly greater (P ≤ 0.05) than that from nonporous solid surface, and overall removal of MNV from both surfaces was significantly less (P ≤ 0.05) than that of FCV and PRD1. Additionally, the terry towel removed significantly fewer total viruses (P ≤ 0.05) than the microfiber and one of the cotton/cellulose cloths. The cleaning cloth experiments were repeated with human norovirus. For transfer of viruses from cloth to surface, both cellulose/cotton cloths and microfiber transferred an average of 3.4 and 8.5 total PFU, respectively, to both surfaces, and the amounts transferred were significantly different (P ≤ 0.05) from those for the nonwoven cloth and terry towel (309 and 331 total PFU, respectively). There was no statistically significant difference (P > 0.05) in the amount of virus transfer between surfaces. These data indicate that while the cleaning cloths assessed here can remove viruses from surfaces, some cloths may also transfer a significant amount of viruses back to food contact surfaces. PMID:22327573

  20. 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.

  1. Control of pyrite surface chemistry in physical coal cleaning

    SciTech Connect

    Luttrell, G.H.; Yoon, R.H.; Ou, Z.S.

    1992-06-24

    The successful separation of pyrite from coal by flotation is dependent to a large extent upon the selectivity of the process, and the use of a pyrite depressant is one of the most important and cost-effective techniques for achieving this. This report evaluates the effects of three factors on the floatability of pyrite. These are (1) the superficial oxidation of pyrite, (2) the contamination of pyrite surfaces by carbonaceous matter, and (3) pulp redox potentials. XPS (x-ray photoelectron spectroscopy) and IR spectrometry have been used to identify surface reaction products. Microflotation, laboratory-scale conventional flotation and microbubble column flotation were used to quantify the effects of these factors. It was found that low (reducing) pulp potentials are effective depressants of pyrite (more so for fresh, unoxidized samples than for oxidized samples), whilst at the same time do not materially affect coal flotation.

  2. 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.

  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. 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.

  5. Light scattering from laser-induced shallow pits on silica exit surfaces

    NASA Astrophysics Data System (ADS)

    Feigenbaum, E.; Raman, R. N.; Nielsen, N.; Matthews, M. J.

    2015-11-01

    We study the formation of laser-induced shallow pits (LSPs) on silica output surfaces and relate these features to optical performance as a function of incident laser fluence. Typical characteristics of the LSPs morphology are presented. Closed-form expressions for the scattered power and far-field angular distribution are derived and validated using numerical calculations of both Fourier optics and FDTD solutions to Maxwell's equations. The model predictions agree well with the measurements for precise profile micro-machined shallow pits on glass, and for pitting caused by laser cleaning of bound metal micro-particles at different fluences.

  6. 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.

  7. 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.

  8. Light alloy upgrading by surface laser treatment

    NASA Astrophysics Data System (ADS)

    Fariaut, Francois; Boulmer-Leborgne, Chantal; Andreazza-Vignolle, Caroline; Sauvage, Thierry; Langlade, Cecile; Frainais, Michel

    2002-09-01

    The excimer laser nitriding and carburizing process reported is developed to enhance the mechanical and chemical properties of aluminum alloys. An excimer laser beam is focused onto the alloy surface in a cell containing 1 bar nitrogen or propylene gas. Vapor plasma expands from the surface then dissociates and ionizes ambient gas. Nitrogen or carbon atoms from plasma in contact with the surface penetrate in depth due to plasma recoil action onto the target surface heated by the plasma. It is thus necessary to work with a sufficient laser fluence to create the plasma, but this fluence must be limited to prevent laser-induced surface roughness. The nitrogen or carbon concentration profiles are determined from nuclear analysis. Crystalline quality is evidenced by X Ray Diffraction (XRD) technique. Transmission Electron Microscopy (TEM) gives the in-depth microstructure. Fretting coefficient measurements exhibit a satisfying behavior for some experimental conditions. The polycrystalline nitride or carbide layer obtained is several micrometers thick and composed of pure A1N or Al4C3 (columnar microstructure) top layer standing on a diffusion layer.

  9. Growth of pentacene on clean and modified gold surfaces

    SciTech Connect

    Kaefer, Daniel; Ruppel, Lars; Witte, Gregor

    2007-02-15

    The growth and evolution of pentacene films on gold substrates have been studied. By combining complementary techniques including scanning tunneling microscopy, atomic force microscopy, scanning electron microscopy, near-edge x-ray-absorption fine structure, and x-ray diffraction, the molecular orientation, crystalline structure, and morphology of the organic films were characterized as a function of film thickness and growth parameters (temperature and rate) for different gold substrates ranging from Au(111) single crystals to polycrystalline gold. Moreover, the influence of precoating the various gold substrates with self-assembled monolayers (SAM's) of organothiols with different chemical terminations has been studied. On bare gold the growth of pentacene films is characterized by a pronounced dewetting while the molecular orientation within the resulting crystalline three-dimensional islands depends distinctly on the roughness and cleanliness of the substrate surface. After completion of the first wetting layer where molecules adopt a planar orientation parallel to the surface the molecules continue to grow in a tilted fashion: on Au(111) the long molecular axis is oriented parallel to the surface while on polycrystalline gold it is upstanding oriented and thus parallels the crystalline orientation of pentacene films grown on SiO{sub 2}. On SAM pretreated gold substrates the formation of a wetting layer is effectively suppressed and pentacene grows in a quasi-layer-by-layer fashion with an upstanding orientation leading to rather smooth films. The latter growth mode is observed independently of the chemical termination of the SAM's and the roughness of the gold substrate. Possible reasons for the different growth mechanism as well as consequences for the assignment of spectroscopic data of thin pentacene film are discussed.

  10. Skin characteristics by laser generated surface waves.

    PubMed

    Huang, Zhihong; L'Etang, Adèle

    2009-01-01

    This paper discusses a study into the suitability of using laser generated surface acoustic waves for the characterisation of skin properties without causing any damage to the skin thermally or by mechanical disruption. Using commercial Finite Element Code ANSYS, the effects of laser wavelength, laser beam radius and laser rise time on generation of laser generated ultrasonic waves in a 3-layered elastic isotropic model of human skin were studied. The FE model is an example of a sequential coupled field analysis where the thermal and mechanical analyses are treated separately. The heating of the skin model due to the short laser pulse is simulated by a dynamic thermal analysis with the laser pulse modeled as volumetric heat generation and the results from this analysis subsequently applied as a load in the mechanical analysis where the out-of-plane displacement histories are analyzed. The technique described in this paper also involves measuring the propagation velocity of SAWs, which are directly related to the material properties, and thickness of layers, this is done over a wide frequency range in order to obtain maximum information regarding the material under test.

  11. 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.

  12. 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

  13. 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.

  14. Reduction of Schottky Reverse Leakage Current Using GaAs Surface Cleaning with UVO3 Treatment

    NASA Astrophysics Data System (ADS)

    Tanimoto, Takuma; Ohbu, Isao; Ohta, Hiroshi; Takatani, Shinichiro

    1999-07-01

    A GaAs surface-cleaning method using UVO3 treatment was developed. The UVO3 treatment involves two processes: GaAs surface oxidation and oxide removal. Surface oxidation is performed by using a mercury lamp at high temperature, such as 180°C. GaAs oxide is removed by NH4OH solution dipping. Spectroscopic ellipsometry and X-ray photoelectron spectroscopy (XPS) study showed that thermally unstable As oxides exist on a non-treated surface; however, surface GaAs oxides are almost completely removed by this treatment. This cleaning method was applied in the field effect transistor (FET)-gate-formation process and, consequently, Schottky leakage current was significantly reduced.

  15. Excimer laser irradiation of metal surfaces

    NASA Astrophysics Data System (ADS)

    Kinsman, Grant

    In this work a new method of enhancing CO2 laser processing by modifying the radiative properties of a metal surface is studied. In this procedure, an excimer laser (XeCl) or KrF) exposes the metal surface to overlapping pulses of high intensity, 10(exp 8) - 10(exp 9) W cm(exp -2), and short pulse duration, 30 nsec FWHM (Full Width Half Maximum), to promote structural and chemical change. The major processing effect at these intensities is the production of a surface plasma which can lead to the formation of a laser supported detonation wave (LSD wave). This shock wave can interact with the thin molten layer on the metal surface influencing to a varying degree surface oxidation and roughness features. The possibility of the expulsion, oxidation and redeposition of molten droplets, leading to the formation of micron thick oxide layers, is related to bulk metal properties and the incident laser intensity. A correlation is found between the expulsion of molten droplets and a Reynolds number, showing the interaction is turbulent. The permanent effects of these interactions on metal surfaces are observed through scanning electron microscopy (SEM), transient calorimetric measurements and Fourier transform infrared (FTIR) spectroscopy. Observed surface textures are related to the scanning procedures used to irradiate the metal surface. Fundamental radiative properties of a metal surface, the total hemispherical emissivity, the near-normal spectral absorptivity, and others are examined in this study as they are affected by excimer laser radiation. It is determined that for heavily exposed Al surface, alpha' (10.6 microns) can be increased to values close to unity. Data relating to material removal rates and chemical surface modification for excimer laser radiation is also discussed. The resultant reduction in the near-normal reflectivity solves the fundamental problem of coupling laser radiation into highly reflective and conductive metals such as copper and aluminum. The

  16. 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.

  17. 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

  18. 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.

  19. Nonequilibrium Atmospheric Pressure Ar/O2 Plasma Jet: Properties and Application to Surface Cleaning

    NASA Astrophysics Data System (ADS)

    Jin, Ying; Ren, Chunsheng; Yang, Liang; Zhang, Jialiang

    2016-02-01

    In this study an atmospheric pressure Ar/O2 plasma jet is generated to study the effects of applied voltage and gas flux rate to the behavior of discharge and the metal surface cleaning. The increase in applied voltage leads to increases of the root mean square (rms) current, the input power and the gas temperature. Furthermore, the optical emission spectra show that the emission intensities of metastable argon and atomic oxygen increase with increasing applied voltage. However, the increase in gas flux rate leads to a reduction of the rms current, the input power and the gas temperature. Furthermore, the emission intensities of metastable argon and atomic oxygen decrease when gas flux rate increases. Contact angles are measured to estimate the cleaning performance, and the results show that the increase of applied voltage can improve the cleaning performance. Nevertheless, the increase of gas flux rate cannot improve the cleaning performance. Contact angles are compared for different input powers and gas flux rates to search for a better understanding of the major mechanism for surface cleaning by plasma jets. supported by National Natural Science Foundation of China (No. 11305017)

  20. Ion beam and laser induced surface modifications

    NASA Astrophysics Data System (ADS)

    Appleton, B. R.

    1984-01-01

    The capabilities of energetic ion beam and laser processing of surfaces are reviewed. Ion implantation doping, ion beam mixing, and laser and electron beam processing techniques are capable of producing new and often unique surface properties. The inherent control of these techniques has led to significant advances in our ability to tailor the properties of solids for a wide range of technological applications. Equally important, these techniques have allowed tests of fundamental materials interactions under conditions not heretofore achievable and have resulted in increased understanding of a broad range of materials phenomena. These include new metastable phase formation, rapid nucleation and crystal growth kinetics, amorphous metals and metaglasses, supersaturated solid solutions and substitutional alloys, interface interactions, solute trapping, laser-assisted chemical modifications, and a host of other.

  1. Chemical Cleaning of Metal Surfaces in Vacuum Systems by Exposure to Reactive Gases.

    DTIC Science & Technology

    1987-11-10

    IS88 CHEMNICAL CLEANING OF METAL SURFACES IN VACUUM SYSTEMS il BY EXPOSURE TO BERG (U) MAINE UNIV AT OR0ON0 LAB FOR SURFACE SCIENCE AND TECHNOLOGY M...Phys. Letters 39 (1976) 113. 196. P.E. Luscher , Surface Sci. 66 (1977) 167. 197. M. Housley and C.A. King, Surface Sci. 62 (1977) 81, 93. 193. M.K. Debe...D.A. King and F.S. Marsh, Surface Sci. 68 (1977) 437. 199. S.P. Withrow, P.E. Luscher and F.M. Propst, 7. Vacuum Sci. Technol. 15 (1978) 511. 200

  2. Composition and method for cleaning embedded soil from surfaces having low gloss coatings

    NASA Astrophysics Data System (ADS)

    Clark, K. G.

    1984-04-01

    A composition for cleaning embedded soil from surfaces coated with flat or low-gloss coatings has elastomeric particles intermixed with a thixotropic solvent emulsion cleaner. The elastomeric particles provide an eraser-like action to absorb deeply entrapped soil so that the cleaner can emulsify or dissolve the soil and wash it away.

  3. 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.

  4. 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.

  5. 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.

  6. The Capability of the Laser Application for Selective Cleaning and the Removal of Different Layers on Wooden Artworks

    NASA Astrophysics Data System (ADS)

    Wiedemann, G.; Pueschner, K.; Wust, H.; Kempe, A.

    We could demonstrate that the laser ablation for the cleaning or the exposure of wooden artwork is a very promising technique. Using a short pulse lasers with a wavelength of approx. 1064 nm the material "wood" has a higher reaction- and damage threshold than the removal threshold of most of the other layer material. This fact can be explained by the lower absorption at this wavelength.

  7. The application of power ultrasound to the surface cleaning of silica and heavy mineral sands.

    PubMed

    Farmer, A D; Collings, A F; Jameson, G J

    2000-10-01

    Power ultrasound may be used in the processing of minerals to clean their surfaces of oxidation products and fine coatings, mainly through the large, but very localised, forces produced by cavitation. Results of the application of power ultrasound to remove iron-rich coatings from the surfaces of silica sand used in glass making and to improve the electrostatic separation of mineral sand concentrates through lowering the resistivity of the conducting minerals (ilmenite and rutile) are presented. Parameters affecting ultrasonic cleaning, such as input power and levels of reagent addition, are discussed. In particular, we present data showing the relationship between power input and the particle size of surface coatings removed. This can be explained by the Derjaguin approximation for the energy of interaction between a sphere and a flat surface.

  8. The thermal decomposition of methanol and methanethiol on the clean and modified Fe(110) surface

    SciTech Connect

    Batteas, J.D.; Rufael, T.S.; Friend, C.M.

    1996-10-01

    The thermal decomposition of methanol and methanethiol on the clean and modified Fe(110) surface has been examined using X-ray photoelectron spectroscopy, low-energy electron diffraction and temperature programmed reaction spectroscopy. Both methanethiol and methanol adsorb on the Fe(110) surface at 100 K with immediate cleavage of the terminal hydrogen to produce methylthiolate (CH{sub 3}S) and methoxy (CH{sub 3}O) coadsorbed with atomic hydrogen on the Fe surface. Heating the sample to 800 K produces gas phase methane and hydrogen, leaving a chemisorbed S overlayer in the case of methylthiolate, while methoxy decomposes via desorbing hydrogen and CO to leave a clean Fe surface. The influence of oxygen and sulfur pre-adsorption on the thermal decomposition of these species will also be described.

  9. Surface Cleaning by Glow Discharge in High-Volume Gas Flow

    DTIC Science & Technology

    1976-04-07

    was used with a #25 size hypodermic needle the results are shown in Table 2. A slightly smaller drop was obtained when using the same size needle coated...small to measure, indicates a surface free of both water and of substances which are hydrophobic. The theory of the significance of the small contact...and its diameter when spread out over the surface of the clean specimen. The experiment data to test the following theory , was accumulated by measuring

  10. Avalanche boron fusion by laser picosecond block ignition with magnetic trapping for clean and economic reactor

    SciTech Connect

    Hora, H.; Korn, G.; Eliezer, S.; Nissim, N.; Lalousis, P.; Giuffrida, L.; Margarone, D.; Picciotto, A.; Miley, G. H.; Moustaizis, S.; Martinez-Val, J. -M.; Barty, C. P. J.; Kirchhoff, G. J.

    2016-10-11

    Measured highly elevated gains of proton–boron (HB11) fusion (Picciottoet al., Phys. Rev. X4, 031030 (2014)) confirmed the exceptional avalanche reaction process (Lalousiset al., Laser Part. Beams 32, 409 (2014); Horaet al., Laser Part. Beams33, 607 (2015)) for the combination of the non-thermal block ignition using ultrahigh intensity laser pulses of picoseconds duration. The ultrahigh accelerationabove$10^{20}~\\text{cm}~\\text{s}^{-2}$ for plasma blocks was theoretically and numerically predicted since 1978 (Hora,Physics of Laser Driven Plasmas(Wiley, 1981), pp. 178 and 179) and measured (Sauerbrey, Phys. Plasmas3, 4712 (1996)) in exact agreement (Horaet al., Phys. Plasmas14, 072701 (2007)) when the dominating force was overcoming thermal processes. This is based on Maxwell’s stress tensor by the dielectric properties of plasma leading to the nonlinear (ponderomotive) force $f_{\\text{NL}}$ resulting in ultra-fast expanding plasma blocks by a dielectric explosion. Combining this with measured ultrahigh magnetic fields and the avalanche process opens an option for an environmentally absolute clean and economic boron fusion power reactor. Finally, this is supported also by other experiments with very high HB11 reactions under different conditions (Labauneet al., Nature Commun.4, 2506 (2013)).

  11. 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.

  12. Analysis of cavitation on the surface of steel under the ultrasonic cleaning

    NASA Astrophysics Data System (ADS)

    Tsybry, I. K.; Vyalikov, I. L.

    2017-02-01

    The article presents: the results of studies on the effects of cavitation on the surface of steel during processing in a liquid medium; the analysis of changes of the microstructure and the microhardness of steel under the effect of cavitation; the features of hardening and destruction of the surface layers of steel with a structure of granular pearlite and the martensitic steel structure. Comparative analysis of the structural transformations of the surface layers of steels 12H17 and U8 allows us to select the optimum time of ultrasonic treatment for a complete cleaning of the surface without destroying it.

  13. Characteristics of laser surface melted aluminum alloys.

    PubMed

    Weinman, L S; Kim, C; Tucker, T R; Metzbower, E A

    1978-03-15

    Specimens of Al-Fe 1-4 w/o, 2024 and 6061 Al have been surface melted with a pulsed Nd-glass laser. A TEM and SEM study showed that the dendrite spacings were from 2500 A to 4000 A which corresponds to a cooling rate of over 10(6) degrees C/sec. Melt depths obtained were in the range of 30-100 microm. No significant surface vaporization was observed at energy densities up to 440 J/cm(2). Fracture surfaces of the commerical alloys demonstrated elongated porosity in the melt areas, probably due to internal hydrogen.

  14. Defining nanoscale metal features on an atomically clean silicon surface with a stencil.

    PubMed

    Linklater, A; Nogami, J

    2008-07-16

    Metal features with nanometer scale edge definition have been created on an atomically clean Si(001) surface with a stencil. These features were subsequently characterized by scanning tunneling microscopy and scanning electron microscopy. The stencil was brought into contact with the substrate while allowing the stencil to pivot so that it self-aligned parallel to the substrate surface. With this simple method, feature edge spreading was reduced to less than 10 nm in the best case. At the same time, atomic resolution images of the metal feature/silicon boundary showed significant spreading of a sub-monolayer of metal beyond the deposited area. This spreading may pose a limit on the ultimate resolution that can be achieved for metals deposited on atomically clean silicon surfaces.

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

    NASA Astrophysics Data System (ADS)

    Wójcik, Marcin; Zuzel, Grzegorz

    2007-03-01

    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.

  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. Study on surface integrity in photomask resist strip and final cleaning processes

    NASA Astrophysics Data System (ADS)

    Singh, Sherjang; Helbig, Stefan; Dress, Peter; Dietze, Uwe

    2009-04-01

    In recent years, photomask resist strip and cleaning technology development was substantially driven by the industry's need to prevent surface haze formation through the elimination of sulfuric acid from these processes. As a result, ozone water was introduced to the resist strip and cleaning processes as a promising alternative to a Sulfuric - Peroxide Mixture (SPM). However, with the introduction of 193i double patterning, EUVL (Extreme Ultraviolet Lithography) and NanoImprint Lithography (NIL) the demand on CD-linewidth control and surface layer integrity is significantly expanded and the use of ozone water is questionable. Ozone water has been found to cause significant damage to metal based mask surface layers, leading to significant changes in optical properties and CD-linewidth shift. In this paper HamaTech APE demonstrates the use of an alternative acid-free resist strip and cleaning process, which not only overcomes the named drawbacks of conventional ozone water use, but reduces resist strip time by 50% to 75%. The surface materials investigated during this study are; chrome absorber layers on binary masks, MoSi based shifters, chrome hard mask layers on EPSM, and ruthenium capping layers on EUV masks. Surface material integrity and CD-stability results using this new, acid-free approach are presented in the following pages.

  19. Interaction of water vapor with clean and oxygen-covered uranium surfaces

    NASA Astrophysics Data System (ADS)

    Winer, K.; Colmenares, C. A.; Smith, R. L.; Wooten, F.

    1987-04-01

    The interaction of water vapor with clean and oxygen-covered high-purity polycrystalline uranium surfaces was studied between 85 and 298 K with thermal desorption spectroscopy (TDS), X-ray photoelectron spectroscopy (XPS), and secondary ion mass spectroscopy (SIMS). Saturation of the uranium surface with oxygen or water vapor produced an asymmetric O1s photoelectron peak that consisted of a main oxide contribution and a small component assigned to strongly chemisorbed oxygen or hydroxyl ions, respectively. Saturation of the clean or oxygen-covered surface with water vapor at 85 K produced multilayer ice that was converted to oxide and adsorbed hydroxyl ions after warming to room temperature. A significant difference in binding energies was observed in the O1s spectra between water vapor adsorption on clean and oxygen-covered surfaces that lends support to the oxygen inhibition of the water vapor-uranium reaction by a surface mechanism. The initial oxidation mechanisms of uranium with oxygen and water vapor are discussed.

  20. 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.

  1. 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.

  2. Oxide-assisted laser surfacing of aluminum

    NASA Astrophysics Data System (ADS)

    Hoepp, E. E.; Kerr, Hugh W.

    1996-04-01

    CO2 laser processing has been carried out on pure aluminum substrates for travel speeds from 0.3 to 6.1 mm/s, using laser powers of about 100 W or 300 W, with various preplaced single or mixed powders including CoO, NiO, SiO2, Fe2O3 or TiO2 usually combined with enough aluminum powder to permit complete reduction of the oxides. The 100 W laser experiments included low, normal and high gravity experiments. The resulting tracks were tested qualitatively for scratch resistance, and examined metallographically. Two types of surfacing were observed; continuous oxide layers produced by melting and an oxidation- reduction reaction of the original oxides with aluminum, and alloying of the substrate by elements reduced by the reaction. Low gravity experiments produced more uniform thicknesses and generally less cracking in the continuous oxides than normal or high gravity experiments. Alloying of the substrate ranged from almost 100% intermetallic layers at low laser powers and low travel speeds to complex mixtures and bands of different phases, depending on the temporal stability of the process, the powder composition and thickness, the laser power and travel speed. Optimization of the process could provide useful wear resistant coatings in a space environment.

  3. Water repellency on a fluorine-containing polyurethane surface: toward understanding the surface self-cleaning effect.

    PubMed

    Wu, Wanling; Zhu, Qingzeng; Qing, Fengling; Han, Charles C

    2009-01-06

    Surface geometrical microstructure and low surface free energy are the two most important factors for a self-cleaning surface. In this study, multiform geometrical microstructured surfaces were fabricated by casting and electrospinning polyurethanes with and without low surface energy segments. The effect of low surface energy on water repellency was evaluated. Low surface energy seems to make a more significant contribution to the static wetting behavior than do dynamic properties such as the improvement of sliding behavior. Sucking disk behavior was brought forward to explain the pinning state of a water droplet on hydrophobic surfaces with high water contact angles (>150 degrees ). A better understanding of the relationship between the static contact angle and the dynamic sliding property was provided.

  4. 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.

  5. Nanostructured Gd3+-TiO2 surfaces for self-cleaning application

    NASA Astrophysics Data System (ADS)

    Saif, M.; El-Molla, S. A.; Aboul-Fotouh, S. M. K.; Ibrahim, M. M.; Ismail, L. F. M.; Dahn, Douglas C.

    2014-06-01

    Preparation of self-cleaning surfaces based on lanthanide modified titanium dioxide nanoparticles has rarely been reported. In the present work, gadolinium doped titanium dioxide thin films (x mol Gd3+-TiO2 where x = 0.000, 0.005, 0.008, 0.010, 0.020 and 0.030 mol) were synthesized by sol-gel method and deposited using doctor-blade method. These films were characterized by studying their structural, optical and electrical properties. Doping with gadolinium decreases the band gap energy and increase conductivity of thin films. The photo self-cleaning activity in term of quantitative determination of the active oxidative species (rad OH) produced on the thin film surfaces was evaluated using fluorescent probe method. The results show that, the highly active thin film is the 0.020 Gd3+-TiO2. The structural, morphology, optical, electrical and photoactivity properties of Gd3+-TiO2 thin films make it promising surfaces for self-cleaning application. Mineralization of commercial textile dye (Remazol Red RB-133, RR) and durability using 0.020Gd3+-TiO2 film surface was studied.

  6. Development of surface swabbing procedures for a cleaning validation program in a biopharmaceutical manufacturing facility.

    PubMed

    Lombardo, S; Inampudi, P; Scotton, A; Ruezinsky, G; Rupp, R; Nigam, S

    1995-12-05

    Validation of direct surface swabbing procedure in conjuction with total organic carbon (TOC) analysis is described for a biopharmaceutical product manufacturing operation. The swabbing technique was found to be very effective in reliably detecting very low levels of residuals for diverse process streams (limit of detection of approximately 0.5microg/cm(2)). However, contaminant recovery was significantly dependent on both the type of contaminant and the processing surface. This study serves as a guide for designing effective cleaning validation protocols based on direct surface swabbing techniques. (c) 1995 John Wiley & Sons, Inc.

  7. A robust superhydrophobic surface and origins of its self-cleaning properties

    NASA Astrophysics Data System (ADS)

    Li, Hao; Yu, Sirong

    2017-10-01

    A hierarchical surface was fabricated by electrodeposition of copper coating and chemical oxidation to form copper oxide, and the surface energy was lowered by chemical modification. The optimum parameters including seven days of chemical modification, 0.12 mol/L of (NH4)2S2O8, 2.5 mol/L of KOH and 60 °C of oxidation temperature were used to fabricate the superhydrophobic surface with a water contact angle up to around 160° and a sliding angle about 3° on a steel substrate. Silver mirror effect and simple calculation showed that the wetting state between a water droplet and the hierarchical superhydrophobic surface was the Cassie state. This superhydrophobic surface had excellent self-cleaning properties for two different sizes (∼ 50 μm and 150 μm) of fly-ash cenospheres, and we gave the reason for its self-cleaning properties by the force involved at the interface. We also investigated the dynamics of water droplets impinging onto the superhydrophobic surface with different impact velocities, ranging from 0.31 m/s to 1.71 m/s, and found that all the water droplets could rebound from the superhydrophobic surface, with no trace of adhesion. In addition, a variety of tests were performed to assess the robustness of the superhydrophobic surfaces.

  8. 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.

  9. Laser Window Surface Finishing and Coating Science

    DTIC Science & Technology

    1975-07-01

    IKlf il fie. r . *ttt\\ mil nlrol’ly h\\ lllm k Itumhvr ■ LasLr windows. Surface finishing, Thin films , Antireflection coatings , 10.6...Zuccaro) During the course of our program it is our objective to prepare antireflection (AR) film coatings for candidate infrared laser window...antireflection coatings under UHV conditions and to compare; these films with (.host- prepared under ordinary vacuum conditions. a. Experimental Results

  10. Comparison of high‐intensity sound and mechanical vibration for cleaning porous titanium cylinders fabricated using selective laser melting

    PubMed Central

    Seiffert, Gary; Sutcliffe, Chris

    2015-01-01

    Abstract Orthopedic components, such as the acetabular cup in total hip joint replacement, can be fabricated using porous metals, such as titanium, and a number of processes, such as selective laser melting. The issue of how to effectively remove loose powder from the pores (residual powder) of such components has not been addressed in the literature. In this work, we investigated the feasibility of two processes, acoustic cleaning using high‐intensity sound inside acoustic horns and mechanical vibration, to remove residual titanium powder from selective laser melting‐fabricated cylinders. With acoustic cleaning, the amount of residual powder removed was not influenced by either the fundamental frequency of the horn used (75 vs. 230 Hz) or, for a given horn, the number of soundings (between 1 and 20). With mechanical vibration, the amount of residual powder removed was not influenced by the application time (10 vs. 20 s). Acoustic cleaning was found to be more reliable and effective in removal of residual powder than cleaning with mechanical vibration. It is concluded that acoustic cleaning using high‐intensity sound has significant potential for use in the final preparation stages of porous metal orthopedic components. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 117–123, 2017. PMID:26426906

  11. Comparison of high-intensity sound and mechanical vibration for cleaning porous titanium cylinders fabricated using selective laser melting.

    PubMed

    Seiffert, Gary; Hopkins, Carl; Sutcliffe, Chris

    2017-01-01

    Orthopedic components, such as the acetabular cup in total hip joint replacement, can be fabricated using porous metals, such as titanium, and a number of processes, such as selective laser melting. The issue of how to effectively remove loose powder from the pores (residual powder) of such components has not been addressed in the literature. In this work, we investigated the feasibility of two processes, acoustic cleaning using high-intensity sound inside acoustic horns and mechanical vibration, to remove residual titanium powder from selective laser melting-fabricated cylinders. With acoustic cleaning, the amount of residual powder removed was not influenced by either the fundamental frequency of the horn used (75 vs. 230 Hz) or, for a given horn, the number of soundings (between 1 and 20). With mechanical vibration, the amount of residual powder removed was not influenced by the application time (10 vs. 20 s). Acoustic cleaning was found to be more reliable and effective in removal of residual powder than cleaning with mechanical vibration. It is concluded that acoustic cleaning using high-intensity sound has significant potential for use in the final preparation stages of porous metal orthopedic components. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 117-123, 2017. © 2015 The Authors Journal of Biomedical Materials Research Part B: Applied Biomaterials Published by Wiley Periodicals, Inc.

  12. Type 304L stainless steel surface microstructure: Performance in hydride storage and acid cleaning

    SciTech Connect

    Clark, E.A.

    1994-07-01

    The performance of stainless steel as the container in hydride storage bed systems has been evaluated, primarily using scanning electron microscopy. No adverse reaction between Type 304L stainless steel and either LaNi{sub 5{minus}x},Al{sub x}, or palladium supported on Kieselguhr granules (silica) during exposure in hydrogen was found in examination of retired prototype storage bed containers and special compatibility test samples. Intergranular surface ditching, observed on many of the stainless steel surfaces examined, was shown to result from air annealing and acid cleaning of stainless steel during normal fabrication. The ditched air annealed and acid cleaned stainless steel samples were more resistant to subsequent acid attack than vacuum annealed or polished samples without ditches.

  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. © 2014 Wiley Periodicals, Inc.

  14. Investigation of surface laser treatment of ancient calcite: the case of the grave in Torricelle (Naples, Italy)

    NASA Astrophysics Data System (ADS)

    Benedetti, D.; Bontempi, E.; Depero, L. E.; Zoncheddu, M.; di Blasio, G.; Bloisi, F.; Vicari, L.; Piccioli, C.

    2006-06-01

    The laser-cleaning technique has been effectively employed in many areas. Recently it has led to a huge development in art restoration. However, this technique must be optimised to remove contaminations and encrustations from surfaces without generating any physical or chemical changes of the original material. Its use has been considered to clean a 4th century B.C. chamber gravesite in Torricelle, near Nola (Naples). The wall painting could not be seen owing to bioorganic surface layer and resinous material originated from surrounding pinewood. In order to evaluate the technique effectiveness we studied the interaction of the light from a Q-switched Nd: YAG equipped with SHG to work at wavelength of 532 nm. Several characterization techniques have been employed to verify the laser effect on the cleaning of the surface versus the operating parameter configuration and to evaluate the possible damages induced by the beam. In particular, micro X-Ray fluorescence (μXRF) provided information on the chemical composition of the clean surface; X-ray microdiffraction (μXRD) was used to identify the phases and their microstructures. These techniques were effective in assessing the quality of the cleaning process and for following the changes in the microstructure of the sample. Preliminary results suggest a possible influence of the laser on the aragonite calcite transformation.

  15. 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

  16. Cleaning of Residues from Equipment Surfaces After Demilitarization of Arsenical-Based Munitions and Fill Materiels

    DTIC Science & Technology

    2007-10-01

    demilitarization process for the destruction of recovered arsenical-based munitions. Presently, this includes the use of PMNSCM’s Explosive Destruction...as the surfaces must be clean in order to achieve a good seal to prevent leaks during operations. A field-useable process for removing the residues was...data generated from the present study will be used to support operation of a non-stockpile demilitarization process for the destruction of recovered

  17. Surface roughness measurement with laser triangulation

    NASA Astrophysics Data System (ADS)

    Bai, Fuzhong; Zhang, Xiaoyan; Tian, Chaoping

    2016-09-01

    A surface roughness measurement method is introduced in the paper, which is based on laser triangulation and digital image processing technique. In the measuring system, we use the line-structured light as light source, microscope lens and high-accuracy CCD sensor as displacement sensor as well. In addition, the working angle corresponding to the optimal sensitivity is considered in the optical structure design to improve the measuring accuracy. Through necessary image processing operation for the light strip image, such as center-line extraction with the barycenter algorithm, Gaussian filtering, the value of roughness is calculated. A standard planing surface is measured experimentally with the proposed method and the stylus method (Mitutoyo SJ-410) respectively. The profilograms of surface appearance are greatly similar in the shape and the amplitude to two methods. Also, the roughness statistics values are close. The results indicate that the laser triangulation with the line-structured light can be applied to measure the surface roughness with the advantages of rapid measurement and visualized display of surface roughness profile.

  18. [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.

  19. Arsenic-Dominated Chemistry in the Acid Cleaning of InGaAs and InAlAs Surfaces

    SciTech Connect

    Sun, Y.; Pianetta, P.; Chen, P.-T.; Kobayashi, M.; Nishi, Y.; Goel, N.; Garner, M.; Tsai, W.

    2008-10-31

    The surface cleaning of InGaAs and InAlAs is studied using Synchrotron Radiation Photoelectron Spectroscopy. Thermal annealing at 400 C can not completely remove the native oxides from those surfaces. Elemental arsenic build-up is observed on both surfaces after acid treatment using HCl, HF or H{sub 2}SO{sub 4} solutions, which is similar to acid-cleaned GaAs surface. Cleaned InGaAs surface is oxide free but small amount of aluminum oxide remains on cleaned InAlAs surface. The common chemical reactions between III-As semiconductors and acid solutions are identified and are found to be dominated by arsenic chemistry.

  20. Surface cleaning of artworks: structure and dynamics of nanostructured fluids confined in polymeric hydrogel networks.

    PubMed

    Mastrangelo, Rosangela; Montis, Costanza; Bonelli, Nicole; Tempesti, Paolo; Baglioni, Piero

    2017-09-13

    Nanosystems and confinement tools for the controlled release of a cleaning agent, e.g., hydrogels and microemulsions, have been used for several years for the treatment of delicate surfaces in art restoration interventions. However, notwithstanding the unprecedented achievements from an application point of view, a fundamental comprehension of their interaction mechanism is still lacking. In this study PVA hydrogels, obtained via freeze-thaw processes, are prepared as scaffolds for water-based nanostructured fluids for application in the cleaning of artworks: rheological, thermal, microscopic and scattering techniques showed that, depending on the number of freeze-thaw cycles, the hydrogels exhibit different physicochemical and viscoelastic properties, making them suitable for application in a broad range of cleaning issues. The gels have been loaded with an oil-in-water microemulsion and the diffusion of the microemulsion droplets inside the polymeric network has been investigated through Fluorescence Correlation Spectroscopy (FCS), demonstrating that the microemulsion is permanently kept inside the matrix and can freely diffuse in the network. In addition, we show that when the gel-microemulsion system is put in contact with a layer of hydrophobic grime, a dynamic interaction between the microemulsion droplets and the underlying layer is established, leading to the solubilization of the hydrophobic molecules inside the droplets in the gel matrix. Thus, for the first time, through FCS, insights into the removal mechanism of hydrophobic grime upon interaction with a cleaning agent embedded in the polymeric matrix are obtained.

  1. 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.

  2. 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.

  3. Fabrication of a Self-Cleaning Surface via the Thermosensitive Copolymer Brush of P(NIPAAm-PEGMA).

    PubMed

    Ye, Yuansong; Huang, Jian; Wang, Xiaolin

    2015-10-14

    Surface hydrophilicity and the inherent washing force are two crucial factors for constructing an underwater self-cleaning surface. Following this self-cleaning mechanism, we fabricated thermosensitive copolymer brushes of N-isopropylacrylamide (NIPAAm) and poly(ethylene glycol) methacrylate (PEGMA) on the polypropylene (PP) surface. Benefiting from the hydrophilic poly(ethylene glycol) (PEG) side chains, the copolymer brushes with the PEGMA content exceeding 5 mol % exhibited good surface hydrophilicity, whenever at temperatures below or above the lower critical solution temperatures (LCST). Hence their underwater oleophobicity was greatly improved with oil contact angles higher than 141° and oil adhesive forces lower than 20 μN. In addition, the sharp volume-phase transition feature was reserved in their copolymer backbones, as proved by the AFM result. Self-cleaning evaluation of the modified surfaces was performed by a simple temperature-change water cleaning method, after which only 0.2 wt % of oil residues remained on the brush surface of P(NIPAAm-5PEGMA) (with 5 mol % of PEGMA contents). The excellent self-cleaning capability is believed to be ascribed to its balanced surface features in hydrophilicity and the sharper volume-phase transition, when a hydrophilic surface can facilitate oil desorption and an intense conformation change of chain stretching and shrinking can offer the strong washing force to assist oil detachment. This study contributes to development of the underwater self-cleaning surface based on a hydrophilic surface with the chain motion.

  4. 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 Central

    Gilbert, R. J.

    1970-01-01

    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

  5. Structural Studies of Clean and Adsorbate-Covered Fcc Metal Surfaces

    NASA Astrophysics Data System (ADS)

    Statiris, Panayiotis Athanasiou

    We have used medium energy ion scattering (MEIS) to study the structural and vibrational properties of the clean metal surfaces of Ni(110) and Ag(111), the structural changes induced by the presence of small amounts ( {~}1 atomic layer) of heteroatoms on the Ni(001) and Ni(110) surfaces (Cs, K, K and CO on Ni(110) and Au on Ni(001)) as well as the arrangement of the heteroatoms on the surface. The thesis consists of five chapters two of which serve as an introduction and provide general information about metal surfaces and medium energy ion scattering (chapters 1 and 2) and three chapters (3, 4, 5) in which the experimental results are being presented, and structural models are proposed for the surfaces studied. The purpose of the material contained in chapter one is to familiarize the reader with the general concepts, and provide an overview of the progress (experimental and theoretical) in the field of clean and adsorbate covered metal surfaces. The second chapter contains an extensive discussion about the principles and applications of medium energy ion scattering. A study of the structure of the clean Ni(001) surface and the K/Ni(110) and K/CO/Ni(110) surfaces is presented in chapter 3. Both the K/Ni(110) and K/CO/Ni(110) exhibit the missing row reconstruction. The change in the surface unit cell observed upon adsorption of CO atoms on the K/Ni(110) surface observed with low energy electron diffraction is due to the ordering of the CO molecules. The growth and structure of thin Au films (0.35 -3 layers) deposited on the Ni(001) surface is the subject of chapter 4. Au forms an almost incommensurate overlayer with a c(2 times 8) unit cell whose structure resembles that of fcc Au(111). The Au atoms exhibit unusually high vibrational amplitudes, indicating the presence of a soft phonon mode as predicted by theoretical work. The growth mode resembles the Stranski-Krastanov mode without exactly following it. The temperature dependence of the vibrational amplitudes

  6. 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.

  7. Clean synthesis of YOF:Er3+, Yb3+ upconversion colloidal nanoparticles in water through liquid phase pulsed laser ablation for imaging applications

    NASA Astrophysics Data System (ADS)

    Anjana, R.; Kurias, K. M.; Jayaraj, M. K.

    2017-10-01

    Upconversion luminescent nanomaterials have great outlook towards imaging applications. These materials have high chemical and thermal stability, low auto fluorescence, high photo stability and IR excitation does not cause photo damage to living cells and penetrate deeply into tissue. Most of the reported nanoparticles are synthesized through chemical methods in which surface modification is needed for dispersing nanoparticles in water. In this paper we report clean and simple synthesis of upconversion luminescent yttrium oxyfluoride (YOF) nanoparticles through laser ablation in deionized water. YOF:Er3+, Yb3+ pellets were used for ablation. Er3+ is the emission centre Yb3+ is the sensitizer. Obtained colloidal solution is transparent to day light and showing red emission on exciting with 980 nm IR laser. By controlling ablation parameters particles of size less than 10 nm dispersed uniformly in water can be obtained through this surfactant free method. The synthesized nanoparticles can be used for cell imaging.

  8. A Facile in Situ and UV Printing Process for Bioinspired Self-Cleaning Surfaces

    PubMed Central

    González Lazo, Marina A.; Katrantzis, Ioannis; Dalle Vacche, Sara; Karasu, Feyza; Leterrier, Yves

    2016-01-01

    A facile in situ and UV printing process was demonstrated to create self-cleaning synthetic replica of natural petals and leaves. The process relied on the spontaneous migration of a fluorinated acrylate surfactant (PFUA) within a low-shrinkage acrylated hyperbranched polymer (HBP) and its chemical immobilization at the polymer-air interface. Dilute concentrations of 1 wt. % PFUA saturated the polymer-air interface within 30 min, leading to a ten-fold increase of fluorine concentration at the surface compared with the initial bulk concentration and a water contact angle (WCA) of 108°. A 200 ms flash of UV light was used to chemically crosslink the PFUA at the HBP surface prior to UV printing with a polydimethylsiloxane (PDMS) negative template of red and yellow rose petals and lotus leaves. This flash immobilization hindered the reverse migration of PFUA within the bulk HBP upon contacting the PDMS template, and enabled to produce texturized surfaces with WCA well above 108°. The synthetic red rose petal was hydrophobic (WCA of 125°) and exhibited the adhesive petal effect. It was not superhydrophobic due to insufficient concentration of fluorine at its surface, a result of the very large increase of the surface of the printed texture. The synthetic yellow rose petal was quasi-superhydrophobic (WCA of 143°, roll-off angle of 10°) and its self-cleaning ability was not good also due to lack of fluorine. The synthetic lotus leaf did not accurately replicate the intricate nanotubular crystal structures of the plant. In spite of this, the fluorine concentration at the surface was high enough and the leaf was superhydrophobic (WCA of 151°, roll-off angle below 5°) and also featured self-cleaning properties. PMID:28773860

  9. 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

  10. Stability investigation of laser darkened metal surfaces

    NASA Astrophysics Data System (ADS)

    Hopp, Béla; Smausz, Tomi; Lentner, Márton; Kopniczky, Judit; Tápai, Csaba; Gera, Tamás; Csizmadia, Tamás; Ehrhardt, Martin; Lorenz, Pierre; Zimmer, Klaus

    2017-09-01

    Pulsed laser irradiation-induced reflectivity decrease of metal surfaces is a well-established phenomenon, which is extensively utilized in numerous applications. Since the stability of these black surfaces is often a demand, we investigated the resistance of darkened copper and titanium surfaces against optical and mechanical damages. For optical stability studies, samples were irradiated by a probe laser beam ( λ = 775 nm, FWHM = 150 fs, f = 1 kHz) at different fluences (0-300 mJ/cm2), while the mechanical stability was studied with scratch test using 2.5 µm radius tip and applying normal force in 29.4-147 µN range. The observed reflectivity and morphological changes indicated that the optical damage threshold fluence is 130 and 160 mJ/cm2 for copper and titanium surfaces, respectively. Mechanical damage only in case of copper could be detected in the applied parameter range indicating a scratch hardness of 21.5 MPa.

  11. Shifted laser surface texturing for bearings applications

    NASA Astrophysics Data System (ADS)

    Houdková, Š.; Šperka, P.; Repka, M.; Martan, J.; Moskal, D.

    2017-05-01

    The laser surface texturing (LST) technologies, based on creation of micro-pattern with pre-defined geometry can positively influence both the friction and wear of tribo-elements. In practice, the integration of LST technology is often limited due to its slowness. The new method, so called shifted laser surface texturing (sLST) with increased process speed was developed to make the technology more attractive for the industrial application. In the paper, the texture created by sLST technology was applied onto the steel samples and Al-Sn-Si surface of sliding bearings. Both block-on-ring (ASTM G-77) laboratory tests of steel samples and high-loaded working application tests on Al-Sn-Si bearings surface were carried out to evaluate the influence of texture on tribological behaviour. The ASTM G-77 laboratory tests showed a positive effect of the texture on friction behaviour. Under the high-loaded testing conditions, the positive effect was observed in initial stages of the tests, decreasing the torque of textured bearings compared to the untreated one. Lately, the texture was worn out and have no influence on the overall wear of the bearings. Based on the above mentioned observations, the use of alternative bearing material with higher hardness or application of protective layer over the created texture was suggested to exploit the texture benefits.

  12. Theory of the clean and hydrogenated Al2O3(0001)-(1×1) surfaces

    NASA Astrophysics Data System (ADS)

    Felice, Rosa Di; Northrup, John E.

    1999-12-01

    We present the results of a first principles investigation of the equilibrium properties of c-plane α-Al2O3 surfaces. The stable structure for the 1×1 clean surface is Al terminated with a stoichiometric composition, while other terminations are unstable independent of surface preparation conditions. We discuss the implications of our results in the frame of possible extended reconstructions. For 1 monolayer of H coverage, we find that the preferred structure has OH dimers both perpendicular and nearly parallel to the surface. H-terminated surfaces may form in suitable preparation conditions. We discuss our results in terms of water adsorption and atomic layer epitaxy of α-Al2O3(0001).

  13. Tracking electron-induced carbon contamination and cleaning of Ru surfaces by Auger electron spectroscopy

    SciTech Connect

    Kanjilal, Aloke; Catalfano, Mark; Harilal, Sivanandan S.; Hassanein, Ahmed; Rice, Bryan

    2012-07-15

    Extreme ultraviolet (EUV) radiation induced growth of carbon and oxygen desorption were investigated on a Ru surface by Auger electron spectroscopy (AES) in the presence and absence of additional photoelectrons (PEs) from a focusing Ru mirror. A decrease in EUV reflectivity with carbon growth in the presence of additional PEs has been observed. Conversely, a carbonaceous Ru surface was cleaned in sequential AES, and discussed in terms of secondary electron assisted dissociation of residual hydrocarbons and water molecules, followed by a chemical reaction between adsorbed carbon and oxygen atoms.

  14. First Principles study of clean and CO covered CeO2 surfaces

    NASA Astrophysics Data System (ADS)

    Grohmann, Rainer; Bihlmayer, Gustav; Vogtenhuber, Doris; Redinger, Joseph; Podloucky, Raimund

    2000-03-01

    By application of a full-potential linearized augmented plane wave method (FLEUR package: G. Bihlmayer, S. Blügel, J. Redinger, R. Podloucky, M. Weinert, D. Vogtenhuber, unpublished.) energetics, relaxed geometry and electronic structure of bulk CeO2 and of its (110) and (111) clean surfaces were calculated. Results and analysis are presented for perfect and O-defect surfaces. Because of the importance of ceria in catalysis adsorption of CO at several high-symmetry positions is studied and discussed.

  15. 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.

  16. Mechanical, chemical and laser treatments of the implant surface in the presence of marginal bone loss around implants.

    PubMed

    Meyle, Joerg

    2012-01-01

    The objective of this review was to summarise current evidence with regard to the decontamination of implant surfaces by mechanical, chemical and physical methods in the presence of marginal bone loss arising from peri-implant infections. A PubMed search identified studies and publications dealing with 'peri-implantitis', 'treatment', 'surface decontamination', 'laser application' 'air-abrasive treatment' and 'photodynamic therapy'. Only studies in international peer-reviewed journals were selected for further evaluation; case reports were not included. Several therapeutic approaches were identified such as mechanical treatment, antiseptics and air-abrasive treatment, photodynamic treatment, and laser applications. Since treatment of infected surfaces with air-powder +/- citric acid, gauze soaked with saline + citric acid or gauze soaked with chlorhexidine led to similar results in experimental studies, cotton pellets with saline may be adequate for cleaning micro-rough surfaces. Antimicrobial photodynamic therapy can effectively reduce the prevalence of pathogens on implant surfaces, but the clinical benefits remain unknown. The increase in temperature of the implant surface caused by the CO2 laser poses a risk. The Er:YAG laser is considered to possess the best properties for implant surface decontamination. In vivo, no single method of surface decontamination (chemical agents, air abrasives or lasers) was found to be superior. In several animal experiments, thorough cleaning of the infected implant surfaces and implantation of these previously infected devices into freshly prepared sites resulted in re-osseointegration, while currently there are no controlled clinical trials where re-osseointegration has been demonstrated in patients. For decontamination of the infected implant surfaces, rinsing with saline (or cleaning with cotton pellets soaked with sterile saline) and air-abrasive treatment seem to work. Laser decontamination of the surface does not improve

  17. Square lattice photonic crystal surface mode lasers.

    PubMed

    Lu, Tsan-Wen; Lu, Shao-Ping; Chiu, Li-Hsun; Lee, Po-Tsung

    2010-12-06

    In this report, we propose a square lattice photonic crystal hetero-slab-edge microcavity design. In numerical simulations, three surface modes in this microcavity are investigated and optimized by tuning the slab-edge termination τ and gradual mirror layer. High simulated quality (Q) factor of 2.3 × 10(5) and small mode volume of 0.105 μm(3) are obtained from microcavity with τ = 0.80. In experiments, we obtain and identify different surface modes lasing. The surface mode in the second photonic band gap shows a very-low threshold of 140 μW and high Q factor of 5,500, which could be an avenue to low-threshold optical lasers and highly sensitive sensor applications with efficient light-matter interactions.

  18. Nondestructive characterization and enzyme cleaning of painted surfaces: assessment from the macro to nano level.

    PubMed

    Pereira, Catarina; Busani, Tito; Branco, Luis C; Joosten, Ineke; Sandu, Irina Crina Anca

    2013-12-01

    This work establishes a multiscale and multitechnique nondestructive approach as valid methodology for monitoring surface properties and evaluating the effectiveness of enzymatic removal of varnishes from paintings/polychrome artefacts. Mock-up samples (documented reconstructions of oil, tempera, and gilded layers on canvas and wooden supports) were covered with different proteinaceous varnishes (egg white, animal and fish glue, casein) and then characterized before and after the removal of these coatings with enzyme-based solutions. The varnish was cleaned in several steps (two dry swabs and two wet swabs) with a clearance step for removing the residues from proteinaceous varnish or from enzyme solution. Microscopy [stereomicroscopy (SM), optical microscopy (OM), atomic force microscopy (AFM), and scanning electron microscopy (SEM)] and colorimetric (CIE L*a*b* system) techniques were used for characterization of the reconstruction surfaces at different scales (macro-scale by SM and OM; micro-scale by SEM and nano-scale by AFM). These techniques were also used to monitor the cleaning treatment. Although results presented in this work were obtained for the specific treatment of enzyme removal, the methodology could be extended to other types of materials and cleaning. Further experiments on real works of art are needed for a complete validation of the methodology.

  19. A method to evaluate the cleaning and disinfectant action of surface disinfectants.

    PubMed

    Walder, M; Myrbäck, K E; Nilsson, B

    1989-02-01

    Surface disinfection tests, used to evaluate new disinfectants, do not take into account the effects of detergents or of the mechanical cleaning process. We describe methods which evaluate both the disinfection and cleaning effect of disinfectants on organic matter. When testing alcohols at high concentrations (greater than or equal to 70%) on blood spots contaminated with Staphylococcus aureus, we found that the organisms were trapped and fixed to the test surface, probably due to denaturation of the blood. This gave a low inactivating factor (IF), as well as a poor subjective cleaning effect (SC). If serum was used instead of blood, we observed less pronounced trapping, resulting in a high IF although the SC was still poor. When broth was used, both IF and SC were satisfactory. With alcohols at a concentration of 42%, trapping was markedly reduced which improved the SC in blood contamination, with serum or broth contamination trapping did not occur. However, 42% ethanol lost its killing effect (i.e. low IF), whereas 42% isopropanol still demonstrated a high IF.

  20. Cleaning of inner vacuum surfaces in the Uragan-3M facility by radio-frequency discharges

    SciTech Connect

    Lozin, A. V. Moiseenko, V. E.; Grigor’eva, L. I.; Kozulya, M. M.; Kulaga, A. E.; Lysoivan, A. I.; Mironov, Yu. K.; Pavlichenko, R. O.; Romanov, V. S.; Chernyshenko, V. Ya.; Chechkin, V. V.; Collaboration: Uragan-3M Team

    2013-08-15

    A method for cleaning vacuum surfaces by a low-temperature (T{sub e} ∼ 10 eV) relatively dense (n{sub e} ≈ 10{sup 12} cm{sup −3}) plasma of an RF discharge was developed and successfully applied at the Uragan-3M torsatron. The convenience of the method is that it can be implemented with the same antenna system and RF generators that are used to produce and heat the plasma in the operating mode and does not require retuning the frequencies of the antennas and RF generators. The RF discharge has a high efficiency from the standpoint of cleaning vacuum surfaces. After performing a series of cleanings by the low-temperature RF discharge plasma (about 20000 pulses), (i) the intensity of the CIII impurity line was substantially reduced, (ii) a quasi-steady operating mode with a duration of up to 50 ms, a plasma density of n{sub e} ≈ 10{sup 12} cm{sup −3}, and an electron temperature of up to T{sub e} ∼ 1 keV was achieved, and (iii) mass spectrometric analysis of the residual gas in the chamber indicated a significant reduction in the impurity content.

  1. 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.

  2. Adsorption, polymerization and decomposition of acetaldehyde on clean and carbon-covered Rh(111) surfaces

    NASA Astrophysics Data System (ADS)

    Kovács, Imre; Farkas, Arnold Péter; Szitás, Ádám; Kónya, Zoltán; Kiss, János

    2017-10-01

    The adsorption and dissociation of acetaldehyde were investigated on clean and carbon-covered Rh(111) single crystal surfaces by electron energy loss spectroscopy (EELS), temperature programmed desorption (TPD), high-resolution electron energy loss spectroscopy (HREELS) and work function (∆φ) measurements. Acetaldehyde is a starting material for the catalytic production of many important chemicals and investigation of its reactions motivated by environmental purposes too. The adsorption of acetaldehyde on clean Rh(111) surface produced various types of adsorption forms. η1-(O)-CH3CHOa and η2-(O,C)-CH3CHOa are developing and characterized by HREELS. η1-CH3CHOa partly desorbed at Tp = 150 K, another part of these species are incorporated in trimer and linear 2D polimer species. The desorption of trimers (at amu 132) were observed in TPD with a peak maximum at Tp = 225 K. Above this temperature acetaldehyde either desorbed or bonded as a stable surface intermediate (η2-CH3CHOa) on the rhodium surface. The molecules decomposed to adsorbed products, and only hydrogen and carbon monoxide were analyzed in TPD. Surface carbon decreased the uptake of adsorbed acetaldehyde, inhibited the formation of polymers, nevertheless, it induced the Csbnd O bond scission and CO formation with 40-50 K lower temperature after higher acetaldehyde exposure.

  3. 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.

  4. 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.

  5. 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.

  6. Assembly of Self-Cleaning Electrode Surface for the Development of Refreshable Biosensors.

    PubMed

    Zhu, Xiaoli; Chen, Yaoyao; Feng, Chang; Wang, Wei; Bo, Bing; Ren, Ruixin; Li, Genxi

    2017-04-04

    Passivation of electrode surface and tedious reconstruction of biosensing architectures have long plagued researchers for the development of electrochemical biosensors. Here, we report a novel self-cleaning electrode by modifying the commonly used working electrode with superhydrophobic and conductive nanocomposite. Owing to the superhydrophobicity and the chemical stability, the electrode avoids passivation result from both adsorption of molecules and oxidation in air. The high conductivity and the high effective area also allow the achievement of enhanced electrochemical signals. On the basis of comprehensive studies on this novel electrode, we have applied it in the fabrication of refreshable electrochemical biosensors for both electro-active and electro-inactive targets. For both cases, detection of the targets can be well performed, and the self-cleaning electrode can be refreshed by simply washing and applied for successive measurements in a long period.

  7. Two-Dimensional Laser-Speckle Surface-Strain Gauge

    NASA Technical Reports Server (NTRS)

    Barranger, John P.; Lant, Christian

    1992-01-01

    Extension of Yamaguchi's laser-speckle surface-strain-gauge method yields data on two-dimensional surface strains in times as short as fractions of second. Laser beams probe rough spot on surface of specimen before and after processing. Changes in speckle pattern of laser light reflected from spot indicative of changes in surface strains during processing. Used to monitor strains and changes in strains induced by hot-forming and subsequent cooling of steel.

  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. Incorporation of iron on the clean and gallium-bilayer GaN(0001) surface

    NASA Astrophysics Data System (ADS)

    González-Hernández, Rafael; López P., William; Moreno-Armenta, María G.; Arbey Rodríguez, Jairo

    2011-04-01

    First-principles calculations of the energetic and magnetic properties of Fe incorporation in various sites on clean and Ga-bilayer GaN(0001) surfaces are presented. Employing a thermodynamic approach, the calculated formation energies demonstrate characteristic features in the structural stability and magnetism of Fe incorporated surfaces depending on the growth condition. It is found that the N-rich conditions produce greater magnetization compared to the Ga-rich condition. N-rich magnetization is attributed to the interface formation of FeN layers on the GaN(0001) surface. In addition, calculations for Fe incorporation in Ga-bilayer terminated surface suggest that it is possible to form a FeGax ferromagnetic alloy by performing the growth under extreme Ga-rich conditions.

  10. Preparation and characterization of atomically clean, stoichiometric surfaces of AIN(0001)

    SciTech Connect

    Mecouch, W.J.; Wagner, B.P.; Reitmeier, Z.J.; Davis, R.F.; Pandarinath, C.; Rodriguez, B.J.; Nemanich, R.J.

    2005-01-01

    In situ exposure of the (0001) surface of AlN thin films to flowing ammonia at 1120 deg. C and 10{sup -4} Torr removes oxygen/hydroxide and hydrocarbon species below the detectable limits of x-ray photoelectron spectroscopy and decreases the Al/N ratio from 1.3 to 1.0. The positions of the Al 2p and the N 1s core level peaks acquired from the cleaned surfaces were 75.0{+-}0.1 eV and 398.2{+-}0.1 eV, respectively, which were similar to the values determined for the as-loaded samples. The cleaning process left unchanged the (1x1) low energy electron diffraction pattern, the step-and-terrace microstructure, and the root mean square roughness values observed for the surfaces of the as-loaded samples; i.e., the surface structure and microstructure were not changed by the high-temperature exposure to ammonia at low pressures. Vacuum annealing under 10{sup -7} Torr at 1175 deg. C for 15 min removed all detectable hydrocarbons; however, it did not remove the oxygen/hydroxide species.

  11. 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.

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

    PubMed

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

    2016-09-02

    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.

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. [The investigation of ultrasound efficacy in cleaning the surface of new endodontic instruments].

    PubMed

    Popović, Jelena; Gasić, Jovanka; Radicević, Goran

    2009-01-01

    Active parts and tips of various new stainless steel and nickel-titanium endodontic instruments can be coated with fragments or metal residues, which can become detached during endodontic treatment. These fragments may obstruct the root canals or even reach the periapical tissue during biomechanical preparation and should be removed before clinical use. The aim of this study was to evaluate the presence of metal residues on both new stainless steel and nickel-titanium endodontic instruments, and to determine the cleaning efficacy of ultrasound using distilled water or disinfectant solution for removing these residues. Forty-eight stainless steel and nickel-titanium instruments were carefully removed from their original packages with dental tweezers, in order to avoid any contact with the cutting flutes and tips. The instruments were evaluated in term of metal debris presence, using scanning electron microscopy (SEM) and x-ray energy-dispersive spectroscopy (EDS). The instruments were then removed from the electron microscopy analysis stubs and placed in an ultrasonic bath for 15 minutes at a frequency of 28 kHz, using distilled water or disinfectant solution. The surfaces of the instruments were re-evaluated after cleaning. Before ultrasound cleaning, a larger amount of metal debris was observed on the nickel-titanium endodontic instruments when compared to those made of stainless steel. The presence of metal particles on the instruments was evaluated by using EDS analysis. The use of ultrasound was effective in removing the metal residues from both types of endodontic instrument surfaces. The use of ultrasound proved to be an efficient method for the removal of metal particles from the surface of new stainless steel and nickel-titanium endodontic instruments.

  19. Two-Period Gratings For Surface-Emitting Lasers

    NASA Technical Reports Server (NTRS)

    Lang, Robert J.

    1991-01-01

    Grating surfaces having two spatial periods tailored to obtain desired proportions of output coupling and inward reflection. Solid-state lasers of type emitting light perpendicularly to their broad surfaces made more efficient. Same principle also applicable to "Annular-Bragg-Grating Surface-Emitting Laser", (NPO-17912).

  20. Growth, characterisation and surface cleaning procedures for high-purity tungsten single crystals

    NASA Astrophysics Data System (ADS)

    Cortenraad, R.; Ermolov, S. N.; Semenov, V. N.; Denier van der Gon, A. W.; Glebovsky, V. G.; Bozhko, S. I.; Brongersma, H. H.

    2001-01-01

    High-purity tungsten (W) single crystals have been prepared by the electron-beam floating zone melting technique. The structural quality of these crystals was subsequently improved by the application of a strain-annealing technique. X-ray diffraction methods revealed the near-perfect crystallographic structure, and confirmed the absence of first- and second-order subgrains. The observation of the anomalous transmission of X-rays through the thick crystals, also referred to as the Borrmann effect, further substantiated the structural perfection of the crystals. Well-ordered clean W surfaces free from all contaminants, were obtained by a two-step heating procedure. First, the crystals were heated to 1500 K in an oxygen atmosphere for the removal of the carbon impurities. Subsequent flashing to high temperatures (approximately 2500 K) removed the excess oxygen remaining on the surface from the carbon-removal procedure. Low-energy ion scattering and Auger electron spectroscopy confirmed that the cleaning procedures removed all impurities and that the crystal faces expose only tungsten in the outermost atomic layers. Low-energy electron diffraction patterns showed unreconstructed (1×1) surfaces for the main crystallographic orientations.

  1. The equilibrium geometry and electronic structure of Bi nanolines on clean and hydrogenated Si(001) surfaces.

    PubMed

    Miwa, R H; Macleod, J M; McLean, A B; Srivastava, G P

    2005-10-01

    The equilibrium geometry, electronic structure and energetic stability of Bi nanolines on clean and hydrogenated Si(001) surfaces have been examined by means of ab initio total energy calculations and scanning tunnelling microscopy. For the Bi nanolines on a clean Si surface the two most plausible structural models, the Miki or M model (Miki et al 1999 Phys. Rev. B 59 14868) and the Haiku or H model (Owen et al 2002 Phys. Rev. Lett. 88 226104), have been examined in detail. The results of the total energy calculations support the stability of the H model over the M model, in agreement with previous theoretical results. For Bi nanolines on the hydrogenated Si(001) surface, we find that an atomic configuration derived from the H model is also more stable than an atomic configuration derived from the M model. However, the energetically less stable (M) model exhibits better agreement with experimental measurements for equilibrium geometry. The electronic structures of the H and M models are very similar. Both models exhibit a semiconducting character, with the highest occupied Bi-derived bands lying at approximately 0.5 eV below the valence band maximum. Simulated and experimental STM images confirm that at a low negative bias the Bi lines exhibit an 'antiwire' property for both structural models.

  2. The equilibrium geometry and electronic structure of Bi nanolines on clean and hydrogenated Si(001) surfaces

    NASA Astrophysics Data System (ADS)

    Miwa, R. H.; MacLeod, J. M.; McLean, A. B.; Srivastava, G. P.

    2005-10-01

    The equilibrium geometry, electronic structure and energetic stability of Bi nanolines on clean and hydrogenated Si(001) surfaces have been examined by means of ab initio total energy calculations and scanning tunnelling microscopy. For the Bi nanolines on a clean Si surface the two most plausible structural models, the Miki or M model (Miki et al 1999 Phys. Rev. B 59 14868) and the Haiku or H model (Owen et al 2002 Phys. Rev. Lett. 88 226104), have been examined in detail. The results of the total energy calculations support the stability of the H model over the M model, in agreement with previous theoretical results. For Bi nanolines on the hydrogenated Si(001) surface, we find that an atomic configuration derived from the H model is also more stable than an atomic configuration derived from the M model. However, the energetically less stable (M) model exhibits better agreement with experimental measurements for equilibrium geometry. The electronic structures of the H and M models are very similar. Both models exhibit a semiconducting character, with the highest occupied Bi-derived bands lying at ~0.5 eV below the valence band maximum. Simulated and experimental STM images confirm that at a low negative bias the Bi lines exhibit an 'antiwire' property for both structural models.

  3. Review of antireflective surface structures on laser optics and windows.

    PubMed

    Busse, Lynda E; Frantz, Jesse A; Shaw, L Brandon; Aggarwal, Ishwar D; Sanghera, Jasbinder S

    2015-11-01

    We present recent advancements in structured, antireflective surfaces on optics, including crystals for high-energy lasers as well as windows for the infrared wavelength region. These structured surfaces have been characterized and show high transmission and laser damage thresholds, making them attractive for these applications. We also present successful tests of windows with antireflective surfaces that were exposed to simulated harsh environments for the application of these laser systems.

  4. 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.

  5. 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.

  6. [Atomic and electronic structure of metals and alloys: Clean surfaces and chemisorbed molecules

    SciTech Connect

    Not Available

    1993-01-01

    Ultrapure Tb was further purified and surface cleaning procedures developed for basal plane and (11[bar 2]0) surface of Tb. Structure of both surfaces was found to be relaxed: (0001) is contracted by 3.9% in the first and expanded by 1.4% in second interlayer spacing; (11[bar 2]0) is contracted by 3.3% in first layer and shows a change in registry. Thin films of Gd, Tb, Dy, Ho, and Er were grown on W[l brace]110[r brace] substrate in ultrahigh vacuum. Studies have been carried out on epitaxial systems involving Cu, Fe and Mn on Fe and Pt, Cu, and Pd substrates, respectively; new metastable crystalline phases have been found. Studies of possible ferromagnetism in 4d elements (Rh, Ru) and relativistic effects in electron band structure of Cu[l brace]111[r brace] have been completed and published. Plans for the following year are given.

  7. 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.

  8. 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.

  9. 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.

  10. Reduction of Clostridium Difficile and vancomycin-resistant Enterococcus contamination of environmental surfaces after an intervention to improve cleaning methods

    PubMed Central

    Eckstein, Brittany C; Adams, Daniel A; Eckstein, Elizabeth C; Rao, Agam; Sethi, Ajay K; Yadavalli, Gopala K; Donskey, Curtis J

    2007-01-01

    Background Contaminated environmental surfaces may play an important role in transmission of some healthcare-associated pathogens. In this study, we assessed the adequacy of cleaning practices in rooms of patients with Clostridium difficile-associated diarrhea (CDAD) and vancomycin-resistant Enterococcus (VRE) colonization or infection and examined whether an intervention would result in improved decontamination of surfaces. Methods During a 6-week period, we cultured commonly touched surfaces (i.e. bedrails, telephones, call buttons, door knobs, toilet seats, and bedside tables) in rooms of patients with CDAD and VRE colonization or infection before and after housekeeping cleaning, and again after disinfection with 10% bleach performed by the research staff. After the housekeeping staff received education and feedback, additional cultures were collected before and after housekeeping cleaning during a 10-week follow-up period. Results Of the 17 rooms of patients with VRE colonization or infection, 16 (94%) had one or more positive environmental cultures before cleaning versus 12 (71%) after housekeeping cleaning (p = 0.125), whereas none had positive cultures after bleach disinfection by the research staff (p < 0.001). Of the 9 rooms of patients with CDAD, 100% had positive cultures prior to cleaning versus 7 (78%) after housekeeping cleaning (p = 0.50), whereas only 1 (11%) had positive cultures after bleach disinfection by research staff (p = 0.031). After an educational intervention, rates of environmental contamination after housekeeping cleaning were significantly reduced. Conclusion Our findings provide additional evidence that simple educational interventions directed at housekeeping staff can result in improved decontamination of environmental surfaces. Such interventions should include efforts to monitor cleaning and disinfection practices and provide feedback to the housekeeping staff. PMID:17584935

  11. Rear-Surface Laser Damage on 355-nm Silica Optics Owing to Fresnel Diffraction on Front-Surface Contamination Particles

    NASA Astrophysics Data System (ADS)

    Génin, François Y.; Feit, Michael D.; Kozlowski, Mark R.; Rubenchik, Alexander M.; Salleo, Alberto; Yoshiyama, James

    2000-07-01

    Light intensity modulations caused by opaque obstacles (e.g., dust) on silica lenses in high-power lasers often enhance the potential for laser-induced damage. To study this effect, particles (10 250 m) with various shapes were sputter deposited on the input surface and irradiated with a 3-ns laser beam at 355 nm. Although a clean silica surface damages at fluences above 15 J cm 2 , a surface contaminated with particles can damage below 11.5 J cm 2 . A pattern that conforms to the shape of the input surface particle is printed on the output surface. Repetitive illumination resulted in catastrophic drilling of the optic. The damage pattern correlated with an interference image of the particle before irradiation. The image shows that the incident beam undergoes phase (and amplitude) modulations after it passes around the particle. We modeled the experiments by calculating the light intensity distribution behind an obscuration by use of Fresnel diffraction theory. The comparison between calculated light intensity distribution and the output surface damage pattern showed good agreement. The model was then used to predict the increased damage vulnerability that results from intensity modulations as a function of particle size, shape, and lens thickness. The predictions provide the basis for optics cleanliness specifications on the National Ignition Facility to reduce the likelihood of optical damage.

  12. Increasing the hydrophobicity degree of stonework by means of laser surface texturing: An application on Zimbabwe black granites

    NASA Astrophysics Data System (ADS)

    Chantada, A.; Penide, J.; Riveiro, A.; del Val, J.; Quintero, F.; Meixus, M.; Soto, R.; Lusquiños, F.; Pou, J.

    2017-10-01

    Tailoring the wetting characteristics of materials has gained much interest in applications related to surface cleaning in both industry and home. Zimbabwe black granite is a middle-to-fine-grained natural stone commonly used as countertops in kitchens and bathrooms. In this study, the laser texturing of Zimbabwe black granite surfaces is investigated with the aim to enhance its hydrophobic character, thus reducing the attachment of contaminants on the surface. Two laser sources (λ = 1064 and 532 nm) were used for this purpose. The treatment is based on the irradiation of the stone by a laser focused on the surface of the targeting sample. The influence of different laser processing parameters on the surface characteristics of granite (wettability, roughness, and chemistry) was statistically assessed. Most suitable laser processing parameters required to obtain the highest hydrophobicity degree were identified. It has been possible to identify the 532 nm laser wavelength as the most effective one to increase the hydrophobic degree of Zimbabwe black granite surface. The phenomenon governing wettability changes was found to be the surface roughness patterns, given the unaltered chemical surface composition after laser processing.

  13. 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%.

  14. Material, Mechanical, and Tribological Characterization of Laser-Treated Surfaces

    NASA Astrophysics Data System (ADS)

    Yilbas, Bekir Sami; Kumar, Aditya; Bhushan, Bharat; Aleem, B. J. Abdul

    2014-10-01

    Laser treatment under nitrogen assisting gas environment of cobalt-nickel-chromium-tungsten-based superalloy and high-velocity oxygen-fuel thermal spray coating of nickel-chromium-based superalloy on carbon steel was carried out to improve mechanical and tribological properties. Superalloy surface was preprepared to include B4C particles at the surface prior to the laser treatment process. Material and morphological changes in the laser-treated samples were examined using scanning electron microscopy, energy-dispersive spectroscopy, and x-ray diffraction (XRD) analysis. Residual stresses present at the surface region of the laser-treated layer were determined from the XRD data. The microhardness of the laser-treated surface was measured by indentation tests. Fracture toughness of the coating surfaces before and after laser treatment were also measured using overload indentation tests. Macrowear and macrofriction characterization were carried out using pin-on-disk tests.

  15. Surface treatment of CFRP composites using femtosecond laser radiation

    NASA Astrophysics Data System (ADS)

    Oliveira, V.; Sharma, S. P.; de Moura, M. F. S. F.; Moreira, R. D. F.; Vilar, R.

    2017-07-01

    In the present work, we investigate the surface treatment of carbon fiber-reinforced polymer (CFRP) composites by laser ablation with femtosecond laser radiation. For this purpose, unidirectional carbon fiber-reinforced epoxy matrix composites were treated with femtosecond laser pulses of 1024 nm wavelength and 550 fs duration. Laser tracks were inscribed on the material surface using pulse energies and scanning speeds in the range 0.1-0.5 mJ and 0.1-5 mm/s, respectively. The morphology of the laser treated surfaces was investigated by field emission scanning electron microscopy. We show that, by using the appropriate processing parameters, a selective removal of the epoxy resin can be achieved, leaving the carbon fibers exposed. In addition, sub-micron laser induced periodic surface structures (LIPSS) are created on the carbon fibers surface, which may be potentially beneficial for the improvement of the fiber to matrix adhesion in adhesive bonds between CFRP parts.

  16. Aluminum metal surface cleaning and activation by atmospheric-pressure remote plasma

    NASA Astrophysics Data System (ADS)

    Muñoz, J.; Bravo, J. A.; Calzada, M. D.

    2017-06-01

    The use of the remote plasma (postdischarge) of argon and argon-nitrogen microwave plasmas for cleaning and activating the surface of metallic commercial aluminum samples has been studied. The influence of the nitrogen content and the distance between the treated samples and the end of the discharge on the hydrophilicity and the surface energy has been analyzed by means of the sessile drop technique and the Owens-Wendt method. A significant increase in the hydrophilicity has been noted in the treated samples, together with an increase in the surface energy from values around 37 mJ/m2 to 77 mJ/m2. Such increase weakly depends on the nitrogen content of the discharge, and the effectivity of the treatment extends to distances up to 5 cm from the end of the discharge, much longer than those reported in other plasma-based treatments. The analysis of the treated samples using X-ray photoelectron spectroscopy reveals that such increase in the surface energy takes place due to a reduction of the carbon content and an increase in the amount of OH radicals in the surface. These radicals tend to disappear within 24-48 h after the treatment when the samples are stored in contact with ambient air, resulting in the ageing of the treated surface and a partial retrieval of the hydrophobicity of the surface.

  17. High resolution electron energy loss spectroscopy of clean and hydrogen covered Si(001) surfaces: first principles calculations.

    PubMed

    Patterson, C H

    2012-09-07

    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.

  18. Scaling of root surfaces with lasers: an in vitro study

    NASA Astrophysics Data System (ADS)

    Sievers, Martin; Frentzen, Matthias; Kosina, A.; Koort, Hans J.

    1993-12-01

    The purpose of this study was to examine the effects of root preparation with different laser types in order to replace hand-held instruments in periodontal surgery. The advantage should be a more selective and atraumatic technique promoting periodontal regeneration. The root surfaces of extracted human teeth were irradiated with pulsed laser radiation of IR lasers (CO2, Ho:YAG and Tm:YAG laser) and excimer lasers (ArF* and XeCl* laser). For the light microscopic investigation the specimen were cut into undecalcified sections of 10 micrometers thickness and stained with Toluidine-blue.

  19. 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.

  20. Cu wetting and interfacial stability on clean and nitrided tungsten surfaces

    NASA Astrophysics Data System (ADS)

    Ekstrom, B. M.; Lee, S.; Magtoto, N.; Kelber, J. A.

    2001-02-01

    Cu growth/nucleation behavior and thermal stability on clean and nitrided tungsten foil have been characterized by Auger electron spectroscopy (AES) and thermal desorption spectroscopy (TDS) under controlled ultra high vacuum (UHV) conditions. At room temperature, Auger intensity ratio versus time plots demonstrate layer by layer Cu growth for the clean tungsten surface (W) and three-dimensional nucleation for the nitride overlayer (7.5-10 Å, WN x/W). Auger intensity ratio versus temperature measurements for the Cu (1 monolayer)/W system indicate a stable interface up to 1000 K. For the Cu (1 ML)/WN x/W system, initial Cu diffusion into the nitride overlayer is observed at 550 K. Maximum diffusion of the Cu occurs at 750 K. The driving force for diffusion is due to an effective Cu-nitride repulsion and a more thermodynamically favorable Cu-W interaction. TDS measurements of the nitride overlayer demonstrate N 2 decomposition from 800-1400 K. The addition of Cu (1 ML) to the nitride overlayer lowers the decomposition temperature range of 750-1350 K. The enhancement of N 2 recombination is attributed to the perturbing effect of Cu on W-N bonding driven by a Cu-W surface alloy formation.

  1. 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.

  2. 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.

  3. In situ work function study of oxidation and thin film growth on clean surfaces

    NASA Astrophysics Data System (ADS)

    Baikie, I. D.; Petermann, U.; Lägel, B.

    1999-08-01

    Using a novel ultra high vacuum compatible Kelvin probe we have studied the work function ( φ) changes on semiconductors and metals occurring during basic surface processing, for example, surface cleaning, sputtering, oxidation and thin film growth. We show that damage of the 7×7 reconstruction due to Ar ion bombardment has a profound influence on the work function changes (Δ φ) during oxidation on the Si(111) surface, tending to decrease or even reverse the surface dipole. We have also followed the variable temperature oxidation kinetics of Si(111) in the range of 100-600 K and show that magnitude of the Δ φpeak during the initial adsorption curve decreases in a linear fashion with increasing substrate temperature. We interpret this as being due to the rapid onset of oxygen permeation through the surface layer at higher temperatures producing a reverse or zero net dipole. Combining work function data with a localized technique such as scanning tunnelling microscopy permits monitoring of surface processes at both microscopic and macroscopic levels. In conjunction with Professor Behm's group at Ulm University, Germany, we have monitored work function changes during evaporation of Al on Ru(0001) and show correlation between changes in φ with topographic features such as island growth mechanism, monolayer formation, etc.

  4. 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.

  5. 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.

  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. 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.

  8. Pre-bonding technology based on excimer laser surface treatment

    NASA Astrophysics Data System (ADS)

    Rotel, M.; Zahavi, J.; Tamir, S.; Buchman, A.; Dodiuk, H.

    2000-02-01

    The application of ArF excimer laser for surface pre-treatment of polycarbonate, polyetherimide, polyaryl ether-ether-ketone (PEEK) composite, fiberglass, aluminum, copper and fused silica was investigated. Various substrates were tested with excimer laser irradiation using various parameters, such as: intensity, repetition rate, and number of pulses. The optimal laser treatment parameters were found for each material needed for achieving maximum adhesional strength of the corresponding bonded joints. Experimental results indicated that UV laser surface treatment improved significantly the adhesion strength compared to conventional treated substrates for all the materials tested. The improved adhesion was correlated with the roughening of the irradiated surface, chemical modification and removal of contamination.

  9. Surface electron acceleration in relativistic laser-solid interactions

    NASA Astrophysics Data System (ADS)

    Chen, Min; Sheng, Zheng-Ming; Zheng, Jun; Ma, Yan-Yun; Bari, Muhammad; Li, Yu-Tong; Zhang, Jie

    2006-04-01

    Under the grazing incidence of a relativistic intense laser pulse onto a solid target, two-dimensional particle-in-cell simulations show that intense quasistatic magnetic and electric fields are generated near the front target surface during the interaction. Some electrons are confined in these quasistatic fields and move along the target surface with betatron oscillations. When this oscillating frequency is close to the laser frequency in the particle frame, these electrons can be accelerated significantly in the reflected laser field, similar to the inverse free-electron-laser acceleration. An analytical model for this surface betatron acceleration is proposed.

  10. High throughput laser texturing of super-hydrophobic surfaces on steel

    NASA Astrophysics Data System (ADS)

    Gemini, Laura; Faucon, Marc; Romoli, Luca; Kling, Rainer

    2017-03-01

    Super-hydrophobic surfaces are nowadays of primary interest in several application fields, as for de-icing devices in the automotive and aerospace industries. In this context, laser surface texturing has widely demonstrated to be an easy one-step method to produce super-hydrophobic surfaces on several materials. In this work, a high average power (up to 40W), high repetition-rate (up to 1MHz), femtosecond infrared laser was employed to produce super-hydrophobic surfaces on 316L steel. The set of process and laser parameters for which the super-hydrophobic behavior is optimized, was obtained by varying the laser energy and repetition rate. The morphology of the textured surfaces was firstly analyzed by SEM and confocal microscope analyses. The contact angle was measured over time in order to investigate the effect of air environment on the hydrophobic properties and define the period of time necessary for the super-hydrophobic properties to stabilize. An investigation on the effect of after-processing cleaning solvents on the CA evolution was carried to assess the influence of the after-processing sample handling on the CA evaluation. Results show that the highest values of contact angle, that is the best hydrophobic behavior, are obtained at high repetition rate and low energy, this way opening up a promising scenario in terms of upscaling for reducing the overall process takt-time.

  11. [Cleaning and disinfection of surfaces in hospitals: Data on structure, process and result in the Frankfurt/Main Metropolitan Area].

    PubMed

    Hausemann, A; Hofmann, H; Otto, U; Heudorf, Ursel

    2015-06-01

    In addition to hand hygiene and reprocessing of medical products, cleaning and disinfection of surfaces is also an important issue in the prevention of germ transmission and by implication infections. Therefore, in 2014, the quality of the structure, process and result of surface preparation of all hospitals in Frankfurt am Main, Germany, was monitored. All 17 hospitals transferred information on the quality of structure. Process quality was obtained through direct observation during cleaning and disinfection of rooms and their plumbing units. Result quality was gained using the fluorescent method, i.e. marking surfaces with a fluorescent liquid and testing if this mark has been sufficiently removed by cleaning. Structure quality: in all hospitals the employees were trained regularly. In 12 of them, the foremen had the required qualifications, in 6 hospitals unclarity as to the intersection of the cleaning and care services remained. In 14 hospitals only visible contamination was cleaned on the weekends, whereas complete cleaning was reported to take place in 12 hospitals on Saturdays and in 2 hospitals on Sundays. The contractually stipulated cleaning (observations specified in brackets) averaged 178 m(2)/h (148 m(2)/h) per patient room and 69 m(2)/h (33 m(2)/h) for bathrooms. Process quality: during process monitoring, various hand contact surfaces were prepared insufficiently. Result quality: 63 % of fluorescent markings were appropriately removed. The need for improvement is given especially in the area of the qualification of the foremen and a in a clear definition of the intersection between cleaning and care services, as well as in the regulations for weekends and public holidays.

  12. Superhydrophobic surfaces fabricated by femtosecond laser with tunable water adhesion: from lotus leaf to rose petal.

    PubMed

    Long, Jiangyou; Fan, Peixun; Gong, Dingwei; Jiang, Dafa; Zhang, Hongjun; Li, Lin; Zhong, Minlin

    2015-05-13

    Superhydrophobic surfaces with tunable water adhesion have attracted much interest in fundamental research and practical applications. In this paper, we used a simple method to fabricate superhydrophobic surfaces with tunable water adhesion. Periodic microstructures with different topographies were fabricated on copper surface via femtosecond (fs) laser irradiation. The topography of these microstructures can be controlled by simply changing the scanning speed of the laser beam. After surface chemical modification, these as-prepared surfaces showed superhydrophobicity combined with different adhesion to water. Surfaces with deep microstructures showed self-cleaning properties with extremely low water adhesion, and the water adhesion increased when the surface microstructures became flat. The changes in surface water adhesion are attributed to the transition from Cassie state to Wenzel state. We also demonstrated that these superhydrophobic surfaces with different adhesion can be used for transferring small water droplets without any loss. We demonstrate that our approach provides a novel but simple way to tune the surface adhesion of superhydrophobic metallic surfaces for good potential applications in related areas.

  13. Improvements In A Laser-Speckle Surface-Strain Gauge

    NASA Technical Reports Server (NTRS)

    Lant, Christian T.

    1996-01-01

    Compact optical subsystem incorporates several improvements over optical subsystems of previous versions of laser-speckle surface-strain gauge: faster acquisition of data, faster response to transients, reduced size and weight, lower cost, and less complexity. Principle of operation described previously in "Laser System Measures Two-Dimensional Strain" (LEW-15046), and "Two-Dimensional Laser-Speckle Surface-Strain Gauge" (LEW-15337).

  14. Laser nanoablation of diamond surface at high pulse repetition rates

    NASA Astrophysics Data System (ADS)

    Kononenko, V. V.; Gololobov, V. M.; Pashinin, V. P.; Konov, V. I.

    2016-10-01

    The chemical etching of the surface of a natural diamond single crystal irradiated by subpicosecond laser pulses with a high repetition rate (f ≤slant 500 {\\text{kHz}}) in air is experimentally investigated. The irradiation has been performed by the second-harmonic (515 {\\text{nm}}) radiation of a disk Yb : YAG laser. Dependences of the diamond surface etch rate on the laser energy density and pulse repetition rate are obtained.

  15. 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.

  16. Field emitter activation on cleaned crystalline niobium surfaces relevant for superconducting rf technology

    NASA Astrophysics Data System (ADS)

    Navitski, A.; Lagotzky, S.; Reschke, D.; Singer, X.; Müller, G.

    2013-11-01

    The influence of heat treatments at 122, 400, and 800°C on the field emission of large-grain and single-crystal high-purity niobium samples has been investigated. Buffered chemical polishing of 40μm and high pressure ultrapure water rinsing under clean-room conditions resulted in smooth surfaces with a linear surface roughness of 46 to 337 nm. By means of field emission scanning microscopy, an increasing number of emitters up to 40/cm2 with temperature were found at surface fields up to 160MV/m. Two different mechanisms of emitter activation were found, i.e. activation by the applied electric field and activation by temperature. Some emitters with an onset surface field of 50 to 100MV/m appeared already after the low-temperature bakeout. Correlated scanning-electron-microscopy/energy-dispersive-x-ray measurements revealed particles and surface defects as emitters. Their activation will be discussed with respect to the thickness of the insulating oxide layer.

  17. 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.

  18. 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.

  19. Removal of peanut allergen Ara h 1 from common hospital surfaces, toys and books using standard cleaning methods.

    PubMed

    Watson, Wade Ta; Woodrow, AnnMarie; Stadnyk, Andrew W

    2015-01-01

    In children, a diagnosis of peanut allergy causes concern about accidental exposure because even small amounts of peanut protein could trigger an allergic reaction. Contamination of toys, books or other items by peanut butter in areas where individuals have eaten may occur in hospital waiting rooms and cafeterias. It is not known if hospital cleaning wipes are effective in removing peanut allergen. The purpose of this study was to determine whether cleaning peanut contaminated items with common household and hospital cleaning wipes would remove peanut allergen. 5 mL of peanut butter was evenly smeared on a 12 inch by 12 inch (30.5 by 30.5 cm) square on a nonporous (laminated plastic) table surface, a plastic doll, and a textured plastic ball, and 2.5 mL was applied to smooth and textured book covers. Samples for measurement of Ara h 1 were collected prior to the application of the peanut butter (baseline), and after cleaning with a common household wipe and two commercial hospital wipes. A monoclonal-based ELISA for arachis hypogaea allergen 1 (Ara h 1), range of detection 1.95-2000 ng/mL, was used to assess peanut allergen on each item. The samples were diluted 1:50 for testing. At baseline, there was no detectable Ara h 1 allergen on any item at baseline. Detectable Ara h 1 was detected on all products after applying peanut butter (range 1.2-19.0 micrograms/mL). After cleaning with any product, no Ara h 1 was detected on any item. Table surfaces, book covers and plastic toys can be cleaned to remove peanut allergen Ara h 1 using common household and hospital cleaning wipes. Regular cleaning of these products or cleaning prior to their use should be promoted to reduce the risk of accidental peanut exposure, especially in areas where they have been used by many children.

  20. 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.

  1. Cleaning and disinfection of biofilms composed of Listeria monocytogenes and background microbiota from meat processing surfaces.

    PubMed

    Fagerlund, Annette; Møretrø, Trond; Heir, Even; Briandet, Romain; Langsrud, Solveig

    2017-06-30

    Surfaces of food processing premises are exposed to regular cleaning and disinfection (C&D) regimes, using biocides that are highly effective against bacteria growing as planktonic cells. However, bacteria growing in surface associated communities (biofilms) are typically more tolerant towards C&D than their individual free cells counterparts, and survival of pathogens such as Listeria monocytogenes may be affected by interspecies interactions within biofilms. In this study, Pseudomonas and Acinetobacter were the most frequently isolated genera surviving on conveyor belts subjected to C&D in meat processing plants. In the laboratory, Pseudomonas, Acinetobacter and L. monocytogenes dominated the community both in suspensions and in biofilms formed on conveyor belts, when cultures were inoculated with eleven-genera cocktails of representative bacterial strains from the identified background flora. When biofilms were exposed to daily C&D cycles, mimicking treatments used in food industry, the levels of Acinetobacter and Pseudomonas mandelii diminished, and biofilms were instead dominated by Pseudomonas putida (65-76%), Pseudomonas fluorescens (11-15%) and L. monocytogenes (3-11%). The dominance of certain species after daily C&D correlated with high planktonic growth rates at 12°C and tolerance to C&D. In single-species biofilms, L. monocytogenes developed higher tolerance to C&D over time, both for the peracetic acid and quaternary ammonium disinfectant, indicating that a broad-spectrum mechanism was involved. Survival after C&D appeared to be a common property of L. monocytogenes strains, as both persistent and sporadic subtypes showed equal survival in complex biofilms. Biofilms established preferentially in surface irregularities of conveyor belts, potentially constituting harborage sites for persistent contamination.IMPORTANCE In food industry, efficient production hygiene is a key measure to avoid accumulation of spoilage bacteria and eliminate pathogens

  2. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Formation of the ion current of a high-temperature femtosecond laser plasma on the target surface containing an impurity layer

    NASA Astrophysics Data System (ADS)

    Volkov, Roman V.; Golishnikov, D. M.; Gordienko, Vyacheslav M.; Dzhidzhoev, M. S.; Lachko, I. M.; Mar'in, B. V.; Mikheev, Pavel M.; Savel'ev, Andrei B.; Uryupina, D. S.; Shashkov, Alexander A.

    2003-11-01

    The effect of an impurity film lying on the surface of a target in a vacuum of up to 10-5 Torr on the ion acceleration in a plasma, which is formed by a 2×1016-W cm-2 femtosecond laser pulse is studied using the time-of-flight and mass spectrometry techniques. It is shown that, under such conditions, the maximum mean energy per unit charge (8 keV) is gained by protons, whereas the ions constituting the target substance (Si, Ti) acquire an energy per unit charge of <1 keV. The use of a <10 J cm-2 nanosecond laser pulse applied 0.1-100 ms before a femtosecond laser pulse allows the target surface to be efficiently cleaned due to the removal of H-, C-, and O-containing molecules from it. Unlike a continuous thermal heating of a surface, the pulse laser cleaning ensures higher heating temperatures and can be efficiently applied to any solid targets in both the thermal and plasma cleaning modes.

  3. [Thermodynamics process of laser drilling on copper surface].

    PubMed

    Li, Shi-Wen; Zhang, Qiu-Hui; Niu, Rui-Hua

    2013-04-01

    The laser drilling experiment was carried out on the copper surface by ns laser pulse, then the micro-morphology of the micro-hole was observed and the thermodynamic process was analyzed accordingly. The research results show that micro-hole is made of the pit in the center and surrounding uplift. The pit becomes deeper with the incident laser pulse energy. The thermodynamic analysis indicates that laser drilling on the metal requires two basic conditions: the first is the deposition of laser pulse energy, which makes the occurrence of melting, vaporization and ionization. Such phase transition can make the materials easy to remove and the laser plasma can accelerate the laser pulse energy deposition as the secondary heat source. The second condition is the production of the laser plasma shock wave, it can eject the materials of phase transition effectively and timely, thus the micro hole can be formed.

  4. 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.

  5. Time-dependent effects of tongue cleaning with mouthwash or mouth moisturising gel on the number of microbes on the tongue surface of elders with care needs.

    PubMed

    Tajima, Sayaka; Ryu, Masahiro; Ogami, Koichiro; Ueda, Takayuki; Sakurai, Kaoru

    2017-08-23

    The purpose of this study was to investigate time-dependent change in the number of microbes on the tongue surface after tongue cleaning using a mouthwash or mouth moisturising gel for elders fed with a feeding tube and with care needs. Twelve elders fed through a feeding tube and with care needs participated in this prospective crossover study. There were four kinds of tongue cleaning modes as follows: (i) tongue cleaning with a mouthwash; (ii) tongue cleaning with a mouth moisturising gel; (iii) tongue cleaning with water; (iv) no tongue cleaning as a negative control. The total number of microbes on the tongue surface was measured using a rapid oral bacteria detection device at baseline, immediately after cleaning, and at 1, 3 and 5 hours after cleaning to evaluate the time-dependent change for each tongue cleaning mode. There were no significant differences regarding microbial count on every measurement in negative control and tongue cleaning with water. There were significant decreases immediately after cleaning, and at 1, 3 and 5 hours after cleaning compared to baseline when the tongue was cleaned with a mouthwash. There was a significant decrease between baseline and immediately after cleaning when the tongue was cleaned with a mouth moisturising gel. Tongue cleaning with mouth moisturising gel decreased the number of microbes on the tongue surface immediately after cleaning, and tongue cleaning with mouthwash decreased it for 5 hours. © 2017 John Wiley & Sons A/S and The Gerodontology Association. Published by John Wiley & Sons Ltd.

  6. 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.

  7. Neutralization of slow multicharged ions at a clean gold surface: Electron-emission statistics

    NASA Astrophysics Data System (ADS)

    Kurz, H.; Aumayr, F.; Lemell, C.; Töglhofer, K.; Winter, Hp.

    1993-09-01

    Emission of slow electrons (Ee<=60 eV) induced by impact of slow multicharged ions (impact velocity vp<=2×105 m/s) onto an atomically clean, polycrystalline gold surface has been studied both experimentally and by numerical simulation, based on the resulting electron-emission statistics. The projectile ions (Nq+, q=5,6; Neq+, q=5-10 Arq+, q=5-16 Krq+, q=5-10 Xeq+, q=6,8,10; Iq+, q=16,20,23,25) have been extracted from a recoil ion source pumped by the GSI UNILAC heavy-ion accelerator in Darmstadt, Germany. We discuss the shape of the experimentally obtained electron-emission statistics and, by means of numerical simulation based on the classical over-the-barrier model put forward recently by Burgdörfer, Lerner, and Meyer [Phys. Rev. A 44, 5674 (1991)], identify the various processes contributing to the ``above-surface'' electron emission, i.e., taking place until projectile impact on the surface. In particular, for impact of slow (E>=50 eV) Ar12+ we show that most of the emitted electrons have energies below 50 eV, with the above-surface-produced fast Auger electrons being a small minority of less than 1%.

  8. Femtosecond laser surface texturing of a nickel-based superalloy

    NASA Astrophysics Data System (ADS)

    Semaltianos, N. G.; Perrie, W.; French, P.; Sharp, M.; Dearden, G.; Watkins, K. G.

    2008-12-01

    Femtosecond laser (180 fs, 775 nm, 1 kHz) surface modification of the nickel-based superalloy C263 is investigated. The laser beam was scanned onto areas on the substrate with macroscopic dimensions using different fluences ( F = 0.28-30 J/cm 2), speeds ( υ = 1-10 mm/s) and number of overscans (5-90). The evolution of surface morphology, roughness, ablation depth and volume ablation rate with laser micromachining parameters were determined. The surface morphology is characterized by ripples for low average powers while for high average powers the surface becomes porous.

  9. Pollution Encrustation Removal by Means of Combined Ultraviolet and Infrared Laser Radiation: The Application of this Innovative Methodology on the Surface of the Parthenon West Frieze

    NASA Astrophysics Data System (ADS)

    Pouli, P.; Frantzikinaki, K.; Papakonstantinou, E.; Zafiropulos, V.; Fotakis, C.

    This study refers to the innovative laser cleaning methodology developed at FORTH IESL on the combination of ultraviolet and infrared laser radiation emitted from a Q-switched Nd:YAG laser for the successful removal of pollution encrustation from marble substrates. The above-mentioned methodology is presented as regards its successful application on the fragile and demanding surface of the Parthenon West Frieze in collaboration with the Committee for the Preservation of the Acropolis Monuments. The aim of this intervention was to remove encrustation, accumulated on the stone due to the atmospheric pollution, without any discoloration or structural alteration to the original surface. The preliminary experiments on all the possible substrates and encrustations present on the surface of the Acropolis monuments and the laser cleaning parameters are presented in detail.

  10. 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.

  11. Kinetic study of Pt nanocrystal deposition on Ag nanowires with clean surfaces via galvanic replacement

    PubMed Central

    2012-01-01

    Without using any templates or surfactants, this study develops a high-yield process to prepare vertical Ag-Pt core-shell nanowires (NWs) by thermally assisted photoreduction of Ag NWs and successive galvanic replacement between Ag and Pt ions. The clean surface of Ag nanowires allows Pt ions to reduce and deposit on it and forms a compact sheath comprising Pt nanocrystals. The core-shell structural feature of the NWs thus produced has been demonstrated via transmission electron microscopy observation and Auger electron spectroscopy elemental analysis. Kinetic analysis suggests that the deposition of Pt is an interface-controlled reaction and is dominated by the oxidative dissolution of Ag atoms. The boundaries in between Pt nanocrystals may act as microchannels for the transport of Ag ions during galvanic replacement reactions. PMID:22559242

  12. Residual Viral and Bacterial Contamination of Surfaces after Cleaning and Disinfection

    PubMed Central

    Tuladhar, Era; Hazeleger, Wilma C.; Koopmans, Marion; Zwietering, Marcel H.; Beumer, Rijkelt R.

    2012-01-01

    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 log10 for poliovirus and close to 4 log10 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-log10 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

  13. 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.

  14. Effects of laser ablation on cemented tungsten carbide surface quality

    NASA Astrophysics Data System (ADS)

    Tan, J. L.; Butler, D. L.; Sim, L. M.; Jarfors, A. E. W.

    2010-11-01

    Although laser micromachining has been touted as being the most promising way to fabricate micro tools, there has been no proper evaluation of the effects of laser ablation on bulk material properties. The current work demonstrates the effects of laser ablation on the properties of a cemented tungsten carbide surface. Of particular interest is the resultant increase in compressive residual stresses in the ablated surface. From this study it is seen that there are no adverse effects from laser ablation of cemented tungsten carbide that would preclude its use for the fabrication of micro-tools but a finishing process may not be avoidable.

  15. Removal of surface contaminants using a chemical-free laser-assisted process

    NASA Astrophysics Data System (ADS)

    Engelsberg, Audrey C.

    1994-10-01

    Contamination control is a critical issue to the manufacture and maintenance of optical components. Particulates and thin films (organic and inorganic) can degrade optical performance. Current cleaning methods are focusing on aqueous-based cleaning and super- critical fluids. Concurrently, environmentally-conscious manufacturing processes are becoming essential for industrial applications. These manufacturing processes emphasize the reduction of water and chemical consumption and hazardous waste production. In this paper, we will introduce a chemical-free laser assisted process that has demonstrated its capability of removing particulates and films from various surfaces including optical. Since this process works with energy flux and a flowing inert gas, it's readily adaptable and cost effective for many industrial applications.

  16. A Comparative Study of Enamel Surface Roughness After Bleaching With Diode Laser and Nd: YAG Laser.

    PubMed

    Mirzaie, Mansoreh; Yassini, Esmaiel; Ganji, Saber; Moradi, Zohreh; Chiniforush, Nasim

    2016-01-01

    Introduction: Bleaching process can affect surface roughness of enamel, which is a vital factor in esthetic and resistance of tooth. The aim of this study was to compare surface roughness of enamel in teeth bleached using Diode and Neodymium-Doped Yttrium Aluminium Garnet (Nd: YAG) lasers with those bleached using conventional method. Methods: In this study, 75 anterior human teeth from upper and lower jaws (These teeth extracted because of periodontal disease) were randomly divided into 5 groups. Group 1: Laser white gel (Biolase, USA) with 45% hydrogen peroxide concentration and GaAlAs Diode laser (CHEESE(TM), GIGAA, China), group 2: Heydent gel (JW, Germany) with 30% Hydrogen peroxide concentration and Diode laser, group 3: Laser white gel and Nd:YAG laser (FIDELIS(TM), Fotona, Slovenia), group 4: Heydent gel and Nd:YAG laser and group 5: The Iranian gel Kimia (Iran) with 35% hydrogen peroxide concentration were used. Surface roughness of the samples was measured using the Surface Roughness Tester system (TR 200 Time Group, Germany) before and after bleaching. In each group, one sample was randomly selected for SEM analysis. Results: The results showed that the mean surface roughness of the teeth before and after bleaching had a significant difference in all the study groups. It was indicated that after bleaching, the mean surface roughness had increased in all the study groups. The highest surface roughness was seen in the conventional bleaching group and the lowest surface roughness was reported in group 3 (laser white gel + diode laser), in which the average surface roughness increased by only 0.1 μm. Conclusion: It was concluded that using the Laser white gel and the diode laser for bleaching resulted in the least surface roughness compared to conventional method.

  17. A Comparative Study of Enamel Surface Roughness After Bleaching With Diode Laser and Nd: YAG Laser

    PubMed Central

    Mirzaie, Mansoreh; Yassini, Esmaiel; Ganji, Saber; Moradi, Zohreh; Chiniforush, Nasim

    2016-01-01

    Introduction: Bleaching process can affect surface roughness of enamel, which is a vital factor in esthetic and resistance of tooth. The aim of this study was to compare surface roughness of enamel in teeth bleached using Diode and Neodymium-Doped Yttrium Aluminium Garnet (Nd: YAG) lasers with those bleached using conventional method. Methods: In this study, 75 anterior human teeth from upper and lower jaws (These teeth extracted because of periodontal disease) were randomly divided into 5 groups. Group 1: Laser white gel (Biolase, USA) with 45% hydrogen peroxide concentration and GaAlAs Diode laser (CHEESETM, GIGAA, China), group 2: Heydent gel (JW, Germany) with 30% Hydrogen peroxide concentration and Diode laser, group 3: Laser white gel and Nd:YAG laser (FIDELISTM, Fotona, Slovenia), group 4: Heydent gel and Nd:YAG laser and group 5: The Iranian gel Kimia (Iran) with 35% hydrogen peroxide concentration were used. Surface roughness of the samples was measured using the Surface Roughness Tester system (TR 200 Time Group, Germany) before and after bleaching. In each group, one sample was randomly selected for SEM analysis. Results: The results showed that the mean surface roughness of the teeth before and after bleaching had a significant difference in all the study groups. It was indicated that after bleaching, the mean surface roughness had increased in all the study groups. The highest surface roughness was seen in the conventional bleaching group and the lowest surface roughness was reported in group 3 (laser white gel + diode laser), in which the average surface roughness increased by only 0.1 μm. Conclusion: It was concluded that using the Laser white gel and the diode laser for bleaching resulted in the least surface roughness compared to conventional method. PMID:28144442

  18. Laser micro-structuring of surfaces for applications in materials and biomedical science

    NASA Astrophysics Data System (ADS)

    Sarzyński, Antoni; Marczak, Jan; Strzelec, Marek; Rycyk, Antoni; CzyŻ, Krzysztof; Chmielewska, Danuta

    2016-12-01

    Laser radiation is used, among others, for surface treatment of various materials. At the Institute of Optoelectronics, under the direction of the late Professor Jan Marczak, a number of works in the field of laser materials processing were performed. Among them special recognition deserves flagship work of Professor Jan Marczak: implementation in Poland laser cleaning method of artworks. Another big project involved the direct method of laser interference lithography. These two projects have already been widely discussed in many national and international scientific conferences. They will also be discussed at SLT2016. In addition to these two projects in the Laboratory of Lasers Applications many other works have been carried out, some of which will be separately presented at the SLT2016 Conference. These included laser decorating of ceramics and glass (three projects completed in cooperation with the Institute of Ceramics and Building Materials), interference structuring medical implants (together with the Warsaw University of Technology), testing the adhesion of thin layers (project implemented together with IFTR PAS), structuring layers of DLC for growing endothelial cells (together with IMMS PAS), engraving glass for microfluidic applications, metal marking, sapphire cutting and finally the production of microsieves for separating of blood cells.

  19. Influence of 527-nm laser light on debris- and shrapnel-contaminated optical surfaces

    NASA Astrophysics Data System (ADS)

    Andrew, James E.; Mann, Karen R.; Tobin, Michael T.; Watson, Joe C.

    2003-05-01

    The use of large aperture high power lasers to study plasmas formed from solid targets is well known. In this paper we consider the effects of second harmonic Neodymium laser radiation [527 nm] on optical surfaces that have been contaminated by solid shrapnel and liquid or gaseous debris arising from the use of laser irradiated solid targets. In typical operations large lasers use debris shields to protect expensive aspheric lenses from optical and mechanical damage. These debris shields have a finite lifetime before they need to be replaced. Criteria for replacement have often been derived empirically from operational experience of evacuated target chambers and may be based on transmission, reflectivity, scatter or obscuration measurements. Here we describe and characterize the debris produced from targets based on gas bags, spall packages and gold halfraums captured on fused silica borosilicate plates. The influence of contamination levels and the physical form of debris on laser beams of various fluences was measured. Laser cleaning, damage thresholds and growth rates were investigated and the techniques are described.

  20. Experimental investigation of the laser ablation process on wood surfaces

    NASA Astrophysics Data System (ADS)

    Panzner, M.; Wiedemann, G.; Henneberg, K.; Fischer, R.; Wittke, Th.; Dietsch, R.

    1998-05-01

    Processing of wood by conventional mechanical tools like saws or planes leaves behind a layer of squeezed wood only slightly adhering to the solid wood surface. Laser ablation of this layer could improve the durability of coatings and glued joints. For technical applications, thorough knowledge about the laser ablation process is necessary. Results of ablation experiments by excimer lasers, Nd:YAG lasers, and TEA-CO 2 lasers on surfaces of different wood types and cut orientations are shown. The process of ablation was observed by a high-speed camera system and optical spectroscopy. The influence of the experimental parameters are demonstrated by SEM images and measurement of the ablation rate depending on energy density. Thermal effects like melting and also carbonizing of cellulose were found for IR- and also UV-laser wavelengths. Damage of the wood surface after laser ablation was weaker for excimer lasers and CO 2-TEA lasers. This can be explained by the high absorption of wood in the ultraviolet and middle infrared spectral range. As an additional result, this technique provides an easy way for preparing wood surfaces with excellently conserved cellular structure.