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Sample records for arf excimer laser

  1. Comparison of KrF and ArF excimer laser treatment of biopolymer surface

    International Nuclear Information System (INIS)

    Highlights: • The influence of ArF and KrF laser on biopolymer surface was determined. • ArF laser acts predominantly on biopolymer surface. • PHB roughness is increased similarly for both applied wavelengths. • Roughness of nanostructures can be precisely controlled. • ArF laser introduces nitrogen on PHB surface. - Abstract: The goal of this work was the investigation of the impact of two different excimer lasers on two biocompatible and biodegradable polymers (poly-L-lactide and poly hydroxybutyrate). Both polymers find usage in medical and pharmaceutical fields. The polymers were modified by KrF and ArF excimer lasers. Subsequently the impact on surface morphology, surface chemistry changes, and thermal properties was studied by means of confocal and AFM microscopy, FTIR and XPS spectroscopy and DSC calorimetry. Under the same conditions of laser treatment it was observed that ArF laser causes more significant changes on surface chemistry, surface morphology and pattern formation on the polymers under investigation. The data obtained in this work can be used for a wide range of possible applications, in tissue engineering or in combination with metallization in electronics, e.g. for biosensors

  2. Comparison of KrF and ArF excimer laser treatment of biopolymer surface

    Energy Technology Data Exchange (ETDEWEB)

    Michaljaničová, I. [Department of Solid State Engineering, University of Chemistry and Technology, 166 28 Prague (Czech Republic); Slepička, P., E-mail: petr.slepicka@vscht.cz [Department of Solid State Engineering, University of Chemistry and Technology, 166 28 Prague (Czech Republic); Heitz, J.; Barb, R.A. [Institute of Applied Physics, Johannes Kepler University Linz, A-4040 Linz (Austria); Sajdl, P. [Department of Power Engineering, University of Chemistry and Technology, 166 28 Prague (Czech Republic); Švorčík, V. [Department of Solid State Engineering, University of Chemistry and Technology, 166 28 Prague (Czech Republic)

    2015-06-01

    Highlights: • The influence of ArF and KrF laser on biopolymer surface was determined. • ArF laser acts predominantly on biopolymer surface. • PHB roughness is increased similarly for both applied wavelengths. • Roughness of nanostructures can be precisely controlled. • ArF laser introduces nitrogen on PHB surface. - Abstract: The goal of this work was the investigation of the impact of two different excimer lasers on two biocompatible and biodegradable polymers (poly-L-lactide and poly hydroxybutyrate). Both polymers find usage in medical and pharmaceutical fields. The polymers were modified by KrF and ArF excimer lasers. Subsequently the impact on surface morphology, surface chemistry changes, and thermal properties was studied by means of confocal and AFM microscopy, FTIR and XPS spectroscopy and DSC calorimetry. Under the same conditions of laser treatment it was observed that ArF laser causes more significant changes on surface chemistry, surface morphology and pattern formation on the polymers under investigation. The data obtained in this work can be used for a wide range of possible applications, in tissue engineering or in combination with metallization in electronics, e.g. for biosensors.

  3. Comparison of KrF and ArF excimer laser treatment of biopolymer surface

    Science.gov (United States)

    Michaljaničová, I.; Slepička, P.; Heitz, J.; Barb, R. A.; Sajdl, P.; Švorčík, V.

    2015-06-01

    The goal of this work was the investigation of the impact of two different excimer lasers on two biocompatible and biodegradable polymers (poly-L-lactide and poly hydroxybutyrate). Both polymers find usage in medical and pharmaceutical fields. The polymers were modified by KrF and ArF excimer lasers. Subsequently the impact on surface morphology, surface chemistry changes, and thermal properties was studied by means of confocal and AFM microscopy, FTIR and XPS spectroscopy and DSC calorimetry. Under the same conditions of laser treatment it was observed that ArF laser causes more significant changes on surface chemistry, surface morphology and pattern formation on the polymers under investigation. The data obtained in this work can be used for a wide range of possible applications, in tissue engineering or in combination with metallization in electronics, e.g. for biosensors.

  4. Photochemical welding of silica microspheres to silicone rubber by ArF excimer laser

    International Nuclear Information System (INIS)

    Transparent fused silica (SiO2) microspheres 2.5 μm in diameter were photochemically welded to transparent, flexible silicone rubber ([SiO(CH3)2]n) substrate by 193 nm ArF excimer laser induced photochemical modification of silicone into silicon oxide. Single layer of silica microspheres was easily formed on an adhesive silicone rubber before laser irradiation after dropping of silica microspheres dispersed in ethanol and subsequent tape peeling. The welding rate, the percentage of welded microspheres tested by ultrasonic cleaning with ethanol, was examined by varying the single pulse fluence and irradiation time of ArF excimer laser. The welding layer underneath microsphere, silicon oxide, was also found to emit white light of strong intensity under UV light illumination.

  5. Pulsed laser deposition of polyhydroxybutyrate biodegradable polymer thin films using ArF excimer laser

    Science.gov (United States)

    Kecskemeti, G.; Smausz, T.; Kresz, N.; Tóth, Zs.; Hopp, B.; Chrisey, D.; Berkesi, O.

    2006-11-01

    We demonstrated the pulsed laser deposition (PLD) of high quality films of a biodegradable polymer, the polyhydroxybutyrate (PHB). Thin films of PHB were deposited on KBr substrates and fused silica plates using an ArF ( λ = 193 nm, FWHM = 30 ns) excimer laser with fluences between 0.05 and 1.5 J cm -2. FTIR spectroscopic measurements proved that at the appropriate fluence (0.05, 0.09 and 0.12 J cm -2), the films exhibited similar functional groups with no significant laser-produced modifications present. Optical microscopic images showed that the layers were contiguous with embedded micrometer-sized grains. Ellipsometric results determined the wavelength dependence ( λ ˜ 245-1000 nm) of the refractive index and absorption coefficient which were new information about the material and were not published in the scientific literature. We believe that our deposited PHB thin films would have more possible applications. For example to our supposal the thin layers would be applicable in laser induced forward transfer (LIFT) of biological materials using them as absorbing thin films.

  6. Pulsed laser deposition of polyhydroxybutyrate biodegradable polymer thin films using ArF excimer laser

    International Nuclear Information System (INIS)

    We demonstrated the pulsed laser deposition (PLD) of high quality films of a biodegradable polymer, the polyhydroxybutyrate (PHB). Thin films of PHB were deposited on KBr substrates and fused silica plates using an ArF (λ = 193 nm, FWHM = 30 ns) excimer laser with fluences between 0.05 and 1.5 J cm-2. FTIR spectroscopic measurements proved that at the appropriate fluence (0.05, 0.09 and 0.12 J cm-2), the films exhibited similar functional groups with no significant laser-produced modifications present. Optical microscopic images showed that the layers were contiguous with embedded micrometer-sized grains. Ellipsometric results determined the wavelength dependence (λ ∼ 245-1000 nm) of the refractive index and absorption coefficient which were new information about the material and were not published in the scientific literature. We believe that our deposited PHB thin films would have more possible applications. For example to our supposal the thin layers would be applicable in laser induced forward transfer (LIFT) of biological materials using them as absorbing thin films

  7. White-Light Emission from Silicone Rubber Modified by 193 nm ArF Excimer Laser

    Science.gov (United States)

    Okoshi, Masayuki; Sekine, Daisuke; Inoue, Narumi; Yamashita, Tsugito

    2007-04-01

    The photochemical surface modification of silicone ([SiO(CH3)2]n) rubber has been successfully demonstrated using a 193 nm ArF excimer laser, and white light of strong intensity was emitted upon exposure to a 325 nm He-Cd laser. The photoluminescence spectra of the modified silicone showed broad peaks centered at 410, 550, and 750 nm wavelengths. The modified surface was carbon-free silicon oxide, and the chemical composition ratio of O/Si was approximately 2. However, the surface was not silica glass (SiO2), as clarified by IR spectroscopy. Instead, nanometer-size particles of silicon oxide were formed on the surface of the modified silicone rubber.

  8. Photo-triggering and secondary electron produced ionization in electric discharge ArF* excimer lasers

    Science.gov (United States)

    Xiong, Zhongmin; Kushner, Mark J.

    2011-10-01

    Electric discharge excimer lasers are sustained in multi-atmosphere attaching gas mixtures that are typically preionized to enable a reproducible, uniform glow, which maximizes optical quality and gain. This preionization is often accomplished using UV light produced by a corona discharge within the plasma cavity. To quantify the relationship between corona discharge properties and those of the laser discharge, the triggering of electron avalanche by preionizing UV light in an electric discharge-pumped ArF* excimer laser was numerically investigated using a two-dimensional model. The preionizing UV fluxes were generated by a corona-bar discharge driven by the same voltage pulse as the main discharge sustained in a multi-atmospheric Ne/Ar/Xe/F2 gas mixture. The resulting peak photo-electron density in the inter-electrode spacing is around 108 cm-3, and its distribution is biased toward the UV source. The preionization density increases with increasing dielectric constant and capacitance of the corona bar. The symmetry and uniformity of the discharge are, however, improved significantly once the main avalanche develops. In addition to bulk electron impact ionization, the ionization generated by sheath accelerated secondary electrons was found to be important in sustaining the discharge current at experimentally observed values. At peak current, the magnitude of the ionization by sheath accelerated electrons is comparable to that from bulk electron impact in the vicinity of the cathode.

  9. Excimer laser system Profile-500

    Science.gov (United States)

    Atejev, V. V.; Bukreyev, V. S.; Vartapetov, Serge K.; Semenov, A. D.; Sugrobov, V. A.; Turin, V. S.; Fedorov, Sergei N.

    1999-07-01

    The description of ophthalmological excimer laser system 'PROFILE-500' for photorefractive and physiotherapeutic keratectomy is presented. Excimer Laser Systems 'PROFILE- 500' are optical system that use ArF excimer lasers to perform photorefractive keratectomy or LASIK; surgical procedures used to correct myopia, hyperopia and astigmatism.

  10. ArF Excimer Laser-induced Deposition of Ag/C Nanocomposite Thin Films in the Presence of n-Hexane

    Czech Academy of Sciences Publication Activity Database

    Gondal, M.A.; Fajgar, Radek; Chang, X.; Shen, K.; Xu, Q.

    2014-01-01

    Roč. 311, AUG 30 (2014), s. 95-100. ISSN 0169-4332 Grant ostatní: NNSFCH(CN) 51172044; NSFJP(CN) BK2011617; KFUPM(CN) RG 1311-1 Institutional support: RVO:67985858 Keywords : ArF excimer laser * nanocomposite * laser deposition Subject RIV: CH - Nuclear ; Quantum Chemistry Impact factor: 2.711, year: 2014

  11. Cathodoluminescence study of ArF excimer laser-induced planarization of large grain diamond films

    OpenAIRE

    Cremades, Ana; Piqueras, J.; Solís Céspedes, Javier

    1996-01-01

    Planarization of large grain diamond films has been induced by 193 nm excimer laser irradiation. Secondary emission images and cathodoluminescence (CL) in the scanning electron microscope have been used to characterize the irradiated area. Irradiation causes changes in the structure of defects involving nitrogen and vacancies. Evolution of the CL signal with the number of pulses indicates that the luminescence intensity tends to stabilize when a smooth film surface is obtained. © 1996 America...

  12. Characterization of calcium phosphate coatings doped with Mg, deposited by pulsed laser deposition technique using ArF excimer laser.

    Science.gov (United States)

    Mróz, W; Jedyński, M; Prokopiuk, A; Slósarczyk, A; Paszkiewicz, Z

    2009-01-01

    Calcium phosphate layers were deposited on Ti6Al4V substrates with TiN buffer layers by use of pulsed laser deposition method. With this technique three pressed pellets consisted of tricalcium phosphate (TCP, Ca(3)(PO(4))(2)), hydroxyapatite (HA, Ca(10)(PO(4))(6)(OH)(2)) and hydroxyapatite-doped with magnesium (HA with 4% of Mg and trace amount of (Ca,Mg)(3)(PO(4))(2)) were ablated using ArF excimer laser (lambda=193 nm). The using of different targets enabled to determine the influence of target composition on the nature of deposited layers. The obtained deposits were characterized by means of Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction method (XRD). The obtained Fourier spectras revealed differences in terms of intensity of spectral bands of different layers. The analysis from XRD showed that Mg-doped HA layer has crystalline structure and TCP and HA layers composition is characterized by amorphous nature. PMID:18407507

  13. The influence of ArF excimer laser micromachining on physicochemical properties of bioresorbable poly(L-lactide)

    Science.gov (United States)

    Stepak, Bogusz D.; Antończak, Arkadiusz J.; Szustakiewicz, Konrad; Pezowicz, Celina; Abramski, Krzysztof M.

    2016-03-01

    The main advantage of laser processing is a non-contact character of material removal and high precision attainable thanks to low laser beam dimensions. This technique enables forming a complex, submillimeter geometrical shapes such as vascular stents which cannot be manufactured using traditional techniques e.g. injection moulding or mechanical treatment. In the domain of nanosecond laser sources, an ArF excimer laser appears as a good candidate for laser micromachining of bioresorbable polymers such as poly(L-lactide). Due to long pulse duration, however, there is a risk of heat diffusion and accumulation in the material. In addition, due to short wavelength (193 nm) photochemical process can modify the chemical composition of ablated surfaces. The motivation for this research was to evaluate the influence of laser micromachining on physicochemical properties of poly(L-lactide). We performed calorimetric analysis of laser machined samples by using differential scanning calorimetry (DSC). It allowed us to find the optimal process parameters for heat affected zone (HAZ) reduction. The chemical composition of the ablated surface was investigated by FTIR in attenuated total reflectance (ATR) mode.

  14. ArF excimer laser-induced deposition of Ag/C nanocomposite thin films in the presence of n-Hexane

    International Nuclear Information System (INIS)

    Highlights: • A new excimer laser ablation process was proposed to fabricate Ag/C thin film. • The size of Ag nanoparticles is ranging from 5 to 20 nm. • The ratios of Ag to C can be controlled by adjusting the pressure of n-Hexane. • The graphite-like structure of carbonaceous products was confirmed. - Abstract: Ag/C nanocomposite thin films with different Ag/C molar ratios have been prepared using ArF excimer laser-induced ablation process and silver target under n-Hexane atmosphere. The morphology, crystal structure and composition of as-deposited Ag/C nanocomposite thin films were investigated with high resolution electronic microscopic techniques (including scanning electron microscopy and transmission electron microscopy) and energy-dispersive X-ray spectroscopy, respectively. Laser Raman spectroscopy and Fourier transform infrared spectroscopy techniques were also applied to characterize the final carbonaceous products generated from n-Hexane under laser ablation process. The optical emission of the plume caused by the interaction between excimer laser and silver target in the presence of n-Hexane was studied to understand the possible reaction process. The UV–vis absorption of as-deposited Ag/C thin films, which is attributed to the surface plasmonic excitation, was also investigated in the present work

  15. Effect of excimer laser (Arf, 193 nm) on aqueous humor during photorefractive keratectomy biophysical and biochemical study

    International Nuclear Information System (INIS)

    Ultraviolet light (193 nm) produced by an excimer laser has been used to produce precise tissue ablation with minimal thermal damage to adjacent tissue. The present study was designed to investigate the effect of excimer laser during photo refractive keratectomy (PRK) on aqueous humor constituents and also the effect of antioxidant enzyme superoxide dismutase (SOD)- applied topically- on these changes if exist. Five groups of schenchilla rabbits were involved in this study, where four groups underwent corneal stromal ablation using argon fluoride excimer laser (Ar F, 193 nm). Two of these four groups were treated with superoxide dismutase intra operatively. The fifth group was used as control one. The obtained results revealed depletion of aqueous humor ascorbate and glutathione contents. Aqueous humor refractive index, cholesterol, phospholipids, malondialdehyde (MDA) and total protein were measured. In conclusion, the excimer laser can induce changes in aqueous humor constituents during PRK. These changes lasted at least for 24 hours and as the time increased to 4 weeks, these changes became limited. The use of exogenous SOD seems to exert beneficial effect on aqueous humor refractive index and total protein

  16. Refractive surgery with the ArF excimer laser (Photorefractive keratectomy) : Surgical technique, wound healing and refractive results

    OpenAIRE

    Hamberg-Nyström, Heléne

    1997-01-01

    Excimer lasers have been adapted to treat refractive errors in the human eye since1987. By remodeling the corneal surface, myopia and astigmatism can be corrected.The investigations herein were performed during a time period when the surgical techniquedevelopment was extensive. It was necessary during this time to evaluate the outcomesin order to document improvement in the refractive results and the quality of vision.The visual outcome and the wound-healing performance are ...

  17. High-power gas-discharge excimer ArF, KrCl, KrF and XeCl lasers utilising two-component gas mixtures without a buffer gas

    Science.gov (United States)

    Razhev, A. M.; Kargapol'tsev, E. S.; Churkin, D. S.

    2016-03-01

    Results of an experimental study of the influence of a gas mixture (laser active medium) composition on an output energy and total efficiency of gas-discharge excimer lasers on ArF* (193 nm), KrCl* (222 nm), KrF* (248 nm) and XeCl* (308 nm) molecules operating without a buffer gas are presented. The optimal ratios of gas components (from the viewpoint of a maximum output energy) of an active medium are found, which provide an efficient operation of laser sources. It is experimentally confirmed that for gas-discharge excimer lasers on halogenides of inert gases the presence of a buffer gas in an active medium is not a necessary condition for efficient operation. For the first time, in two-component gas mixtures of repetitively pulsed gas-discharge excimer lasers on electron transitions of excimer molecules ArF*, KrCl*, KrF* and XeCl*, the pulsed energy of laser radiation obtained under pumping by a transverse volume electric discharge in a low-pressure gas mixture without a buffer gas reached up to 170 mJ and a high pulsed output power (of up to 24 MW) was obtained at a FWHM duration of the KrF-laser pulse of 7 ns. The maximal total efficiency obtained in the experiment with two-component gas mixtures of KrF and XeCl lasers was 0.8%.

  18. Excimer Laser Technology

    CERN Document Server

    Basting, Dirk

    2005-01-01

    This comprehensive survey on Excimer Lasers investigates the current range of the technology, applications and devices of this commonly used laser source, as well as the future of new technologies, such as F2 laser technology. Additional chapters on optics, devices and laser systems complete this compact handbook. A must read for laser technology students, process application researchers, engineers or anyone interested in excimer laser technology. An effective and understandable introduction to the current and future status of excimer laser technology.

  19. A trial of Fe(Se{sub 1-x}Te{sub x}) thin film fabrication by pulsed laser deposition using ArF excimer laser

    Energy Technology Data Exchange (ETDEWEB)

    Yoshimoto, T; Kiss, T; Inoue, M; Kai, H; Teranishi, R; Mori, N; Mukaida, M [Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan); Ichino, Y; Yoshida, Y [Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8603 (Japan); Matsumoto, K [Kyushu Institute of Technology, 1-1 Sensui-cho, Tobata-ku, Kitakyushu, Fukuoka, 804-8550 (Japan); Ichinose, A, E-mail: yoshimoto07@zaiko10.zaiko.kyushu-u.ac.j [Central Research Institute of Electric Power Industry, 2-6-1 Nagasaka, Yokosuka, Kanagawa 240-0196 (Japan)

    2010-06-01

    We fabricated Fe(Se{sub 1-x}Te{sub x}) thin films on LSAT(100), MgO(001), R-Al{sub 2}O{sub 3} substrates by ArF excimer pulsed laser deposition (ArF-PLD) and investigated pulse repetition rate dependence on film growth of Fe(Se{sub 1-x}Te{sub x}) thin films in ArF-PLD. Through x-ray diffraction measurements of Fe(Se{sub 1-x}Te{sub x}) thin films grown by ArF-PLD, 00l peaks of Fe(Se{sub 1-x}Te{sub x}) were confirmed in Fe(Se{sub 1-x}Te{sub x}) thin films grown by pulse repetition rate of 10 Hz but the 00l peaks were not confirmed in Fe(Se{sub 1-x}Te{sub x}) thin films grown at 5 Hz. Atomic force microscopy (AFM) revealed that 100 {approx} 250 nm sized grains were formed on surface of the thin films grown at 10 Hz. It was found that the thin films grown at 5 Hz were formed thinner than those grown at 10 Hz, in spite of the same pulses. Energy dispersive x-ray spectroscopy (EDX) analysis revealed that composition elements of the thin films grown at 5 Hz were re-evaporated from them more than those grown at 10Hz. In {rho}-T measurements of the thin films grown at 10 Hz, it was confirmed that the thin films has T{sub Conset} = 6.5 {approx} 10.5 K and T{sub C0} of the Fe(Se{sub 1-x}Te{sub x}) thin film on an MgO substrate is 3.9 K.

  20. Excimer laser applications

    International Nuclear Information System (INIS)

    This lecture deals with laser induced material photoprocessing, especially concerning those processes which are initiated by u.v. lasers (mostly excimer laser). Advantages of using the u.v. radiation emitted by excimer lasers, both in photophysical and photochemical processes of different materials, are discussed in detail. Applications concerning microelectronics are stressed with respect to other applications in different fields (organic chemistry, medicine). As further applications of excimer lasers, main spectroscopic techniques for ''on line'' diagnostics which employ excimer pumped dye lasers, emitting tunable radiation in the visible and near u.v. are reviewed

  1. Study on high pressure plasma produced by ArF laser

    OpenAIRE

    Tsuda, Norio; Yamada, Jun

    2004-01-01

    When an ArF excimer laser beam was focused in a high pressure argon gas from 50 to 130 atm, the plasma development is observed by streak camera from side window of chamber. The high pressure ArF laser plasma develops symmetrically and the plasma produced by ArF excimer laser hardly develops as compared with the plasma produced by XeCl. The photon energy of ArF laser light is higher than the XeCl laser. The transmittance of ArF laser light was measured. Almost all the laser light is transmitte...

  2. Electrodeless excimer laser

    International Nuclear Information System (INIS)

    In this paper it is proposed how to build an excimer laser based on an electrodeless discharge (or Dielectric Barrier Discharge). Such laser could operate with a low energy per pulse (2 excimer molecule, whose emission wavelength in the VUV range (157 nm) at high reprate is particularly interesting in the micro-lithography field

  3. Excimer laser induced patterning of polymeric surfaces

    International Nuclear Information System (INIS)

    The micropatterning of a surface modified polyurethane is proposed in this paper. In previous work, we described the development and characterisation of a series segmented polyurethanes. These polymers are irradiated with UV excimer lasers (ArF: λ=193 nm and KrF: λ=248 nm excimer laser). After determining the ablation properties of the synthesised polymers, one of these polyurethanes is selected and treated with a new developed method to graft hydrophilic polyacrylamide onto the hydrophobic surface. This modification is observed with spectral reflectance IR, static contact angle measurements, scanning electron and atomic force microscopy. This substrate is treated with an UV excimer laser (ArF, 193 nm) for micropatterning. The grafted polyacrylamide layer shows no interference with the patterning procedure: the polyurethane keeps its good ablation properties in terms of no debris formation and cavities with high dimensional quality (sharp edges and low surface roughness), measured with atomic force microscopy. Also the modification with PEO-macromonomers is executed (AFM, attenuated total reflectance IR and scanning electron microscopy) and shows promising results for a successful usage towards the patterning procedure. This combination of surface modification and micropatterning with UV excimer lasers can be of value in the development of new biosensors

  4. Tunable excimer lasers

    International Nuclear Information System (INIS)

    The wide bandwidth nature of the rare-gas halide excimer transitions allow reasonable tuning of the laser oscillation wavelength that makes it useful for a number of applications. At the same time this wide bandwidth makes narrow band operation difficult and special techniques are needed to insure narrow frequency lasing as well as absolute frequency resettability. The author discusses briefly some of the classical frequency narrowing techniques and then goes on to some recent work that require lasers of special frequency characteristics for special applications including KrF laser fusion

  5. Excimer laser photoresist stripping

    Science.gov (United States)

    Genut, Menachem; Tehar-Zahav, Ofer; Iskevitch, Eli; Livshits, Boris

    1996-06-01

    A new method for stripping the most challenging photoresists on deep sub-micron technology semiconductor wafers has been developed. The method uses a combination of UV excimer laser ablation and reactive chemistry to strip the photoresist in a single dry process, eliminating the wet acids or solvents often used following ashing of high dose implantation (HDI) and reactive ion etching (RIE). The stripping process combines new removal mechanisms: chemical assisted UV excimer laser ablation/etching, laser induced chemical etching of side walls and residues, and enhanced combustion. During the laser pulses photolysis of the process gas occurs, UV laser radiation breaks the photoresist polymer chain bonds, and the photoresist (including foreign materials imbedded in it) is ablated. The combustion is ignited by the ablative impact of laser radiation and enhanced by the radicals formed during photo-thermal decomposition of the process gases. Following this process, the volatilized products and gases are evacuated. The optimum laser stripping conditions were developed to provide a wide process window for the most challenging stripping conditions, such as after HDI and RIE (metal, polysilicon), without causing damage to the wafer devices. A photoresist stripping system based on the described technology was designed and built. The system has been designated as the L-StripperTM and provides stripping time of 0.15 s/(micrometer cm2).

  6. Excimer laser technology

    International Nuclear Information System (INIS)

    Scaling presently available excimer laser systems to lasers designed to operate at high average power and high pulse repetition rates for long periods of time requires advances in many areas of engineering technology. For economical application to industrial processes, the efficiency must be increased. This leads to more stringent requirements on preionization techniques, energy delivery systems, and system chemistry. Long life operation (> 109 to 1010 pulses) requires development of new pulse power components, optical elements and flow system components. A broad-based program underway at the Los Alamos Scientific Laboratory is addressing these key technology issues, with the help of advanced component and systems development programs in industry. A prototype XeCl laser meeting all requirements for efficiency, system performance and life is scheduled for completion in 1984

  7. Surface Modification of Titanium Dental Implants by Excimer Laser

    OpenAIRE

    Radnai, M.; Bereznai, M.; Pelseczi, I.; Toth, Z.; Turzo, K.; Bor, Z.; Fazekas, A.

    2002-01-01

    The perfect osseointegration process of the dental implants depends among other factors on the surfact characteristics of the titanium. In this study enlarged mechanical roughness was produced by a laser-based technique, in order to decrease the healing period of the implant. There are different ways of forming laser induced surface structures. In the case of mask projection techniques the surface can be modified in larger areas and surface patterns. An ArF nanosecond excimer laser was use...

  8. New 223-nm excimer laser surgical system for photorefractive keratectomy

    Science.gov (United States)

    Bagaev, Sergei N.; Razhev, Alexander M.; Zhupikov, Andrey A.

    1999-02-01

    The using of KrCl (223 nm) excimer laser in ophthalmic devices for Photorefractive Keratectomy (PRK) and phototherapeutic Keratectomy (PTK) is offered. The structure and functions of a new surgical UV ophthalmic laser systems Medilex using ArF (193 nm) or KrCl (223 nm) excimer laser for corneal surgery are presented. The systems Medilex with the new optical delivery system is used for photoablative reprofiling of the cornea to correct refraction errors (myopia, hyperopia and astigmatism) and to treat a corneal pathologies. The use of the 223 nanometer laser is proposed to have advantages over the 193 nanometer laser. The results of application of the ophthalmic excimer laser systems Medilex for treatment of myopia are presented.

  9. Triggering Excimer Lasers by Photoionization from Corona Discharges

    Science.gov (United States)

    Xiong, Zhongmin; Duffey, Thomas; Brown, Daniel; Kushner, Mark

    2009-10-01

    High repetition rate ArF (192 nm) excimer lasers are used for photolithography sources in microelectronics fabrication. In highly attaching gas mixtures, preionization is critical to obtaining stable, reproducible glow discharges. Photoionization from a separate corona discharge is one technique for preionization which triggers the subsequent electron avalanche between the main electrodes. Photoionization triggering of an ArF excimer laser sustained in multi-atmosphere Ne/Ar/F2/Xe gas mixtures has been investigated using a 2-dimensional plasma hydrodynamics model including radiation transport. Continuity equations for charged and neutral species, and Poisson's equation are solved coincident with the electron temperature with transport coefficients obtained from solutions of Boltzmann's equation. Photoionizing radiation is produced by a surface discharge which propagates along a corona-bar located adjacent to the discharge electrodes. The consequences of pulse power waveform, corona bar location, capacitance and gas mixture on uniformity, symmetry and gain of the avalanche discharge will be discussed.

  10. Matrix metalloproteinase expression in excimer laser wounded rabbit corneas

    Science.gov (United States)

    Hahn, Taewon; Chamon, Wallace; Akova, Yonja; Stark, Walter J.; Stetler-Stevenson, William G.; Azar, Dimitri T.

    1994-06-01

    This study was performed to obtain information about matrix metalloproteinase (MMP) expression in excimer-wounded corneas and to determine whether MMPs expression correlates with the depth of the ablation. 6-mm excimer keratectomy (60 or 180 micrometers ) was performed using the 193-mm ArF excimer laser on 12 NZW rabbits. Corneas treated with mechanical epithelial debridement and untreated corneas served as controls. Rabbits were killed at 20 and 30 hr after laser ablation. Zymography after SDS extraction was performed on regenerated central epithelium and the central stroma to determine MMPs expression. We observed enzymatic activity of a 92 KDa band in the epithelium of excimer-ablated corneas but not in that following debridement wounds and untreated controls. The expression of the 92 KDa MMP was most pronounced with the deeper excimer ablation. A 72 KDa band of enzymatic activity present in the stroma of all treated and control eyes was also seen in the epithelium of excimer-ablated corneas. These proteolytic enzymes may play an important role in wound healing and remodelling after excimer keratectomy.

  11. Retinal detachment following excimer laser

    OpenAIRE

    Charteris, D; Cooling, R; Lavin, M; McLeod, D

    1997-01-01

    AIMS—To report the clinical presentation, surgical management, and outcome of retinal detachment following excimer laser.
METHODS—Retrospective analysis of retinal detachments observed in 11 eyes of 10 myopic patients who had previously undergone photorefractive keratectomy (PRK) or phototherapeutic keratectomy (PTK) by excimer laser.
RESULTS—Symptoms of visual loss in two eyes were initially attributed to corneal haze. In 10 of 11 eyes visualisation of the retinal detachment and causative br...

  12. Excimer laser debridement of necrotic erosions of skin without collateral damage

    Science.gov (United States)

    Wynne, James J.; Felsenstein, Jerome M.; Trzcinski, Robert; Zupanski-Nielsen, Donna; Connors, Daniel P.

    2011-07-01

    Pulsed ArF excimer laser radiation at 6.4 eV, at fluence exceeding the ablation threshold, will debride burn eschar and other dry necrotic erosions of the skin. Debridement will cease when sufficiently moist viable tissue is exposed, due to absorption by aqueous chloride ions (Cl-) through the non-thermal process of electron photodetachment, thereby inhibiting collateral damage to the viable tissue. ArF excimer laser radiation debrides/ablates ~1 micron of tissue with each pulse. While this provides great precision in controlling the depth of debridement, the process is relatively time-consuming. In contrast, XeCl excimer laser radiation debrides ~8 microns of tissue with each pulse. However the 4.0 eV photon energy of the XeCl excimer laser is insufficient to photodetach an electron from a Cl- ion, so blood or saline will not inhibit debridement. Consequently, a practical laser debridement system should incorporate both lasers, used in sequence. First, the XeCl excimer laser would be used for accelerated debridement. When the necrotic tissue is thinned to a predetermined thickness, the ArF excimer laser would be used for very precise and well-controlled debridement, removing ultra-thin layers of material with each pulse. Clearly, the use of the ArF laser is very desirable when debriding very close to the interface between necrotic tissue and viable tissue, where the overall speed of debridement need not be so rapid and collateral damage to viable tissue is undesirable. Such tissue will be sterile and ready for further treatment, such as a wound dressing and/or a skin graft.

  13. Excimer Laser Pulse Compress With Pulse Feedback

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>To attain a shorter laser pulse, a compressing technique called pulse feedback was developed from the saturation gain switch applied to the amplification in a discharge pumping excimer laser cavity. It can

  14. Excimer lasers drive large-area microprocessing

    Science.gov (United States)

    Delmdahl, Ralph; Tapié, Jean-Luc

    2012-09-01

    Excimer lasers emitting in the UV to far UV region are by nature the laser sources enabling the highest optical resolution and strongest material-photon interaction. At the same time, excimer lasers deliver unmatched UV pulse energies and output powers up to the kilowatt range. Thus, they are the key to fast and effective large area processing of smallest structures with micron precision. As a consequence, excimer lasers are the UV technology of choice when it comes to high-performance microstructuring with unsurpassed quality and process repeatability in applications such as drilling advanced ink jet nozzles or patterning biomedical sensor structures.

  15. Excimer lasers drive large-area microprocessing

    International Nuclear Information System (INIS)

    Highlights: ► Multi-hundred watt UV excimer lasers are used in industrial high-volume microprocessing. ► Excimer laser operational lifetime of two years under typical production conditions yields affordable high power UV laser processing. ► Laser lift-off processing of LEDs is facilitated by the large per-shot-area of excimer lasers. - Abstract: Excimer lasers emitting in the UV to far UV region are by nature the laser sources enabling the highest optical resolution and strongest material–photon interaction. At the same time, excimer lasers deliver unmatched UV pulse energies and output powers up to the kilowatt range. Thus, they are the key to fast and effective large area processing of smallest structures with micron precision. As a consequence, excimer lasers are the UV technology of choice when it comes to high-performance microstructuring with unsurpassed quality and process repeatability in applications such as drilling advanced ink jet nozzles or patterning biomedical sensor structures.

  16. 308-nm excimer laser in endodontics

    Science.gov (United States)

    Liesenhoff, Tim

    1992-06-01

    Root canal preparation was performed on 20 extracted human teeth. After opening the coronal pulp, the root canals were prepared by 308 nm excimer laser only. All root canals were investigated under SEM after separation in the axial direction. By sagittal separation of the mandibles of freshly slaughtered cows, it was possible to get access to the tissues and irradiate under optical control. Under irradiation of excimer laser light, tissue starts to fluoresce. It was possible to demonstrate that each tissue (dentin, enamel, bone, pulpal, and connective tissue) has a characteristic spectral pattern. The SEM analyses showed that it is well possible to prepare root canals safely. All organic soft tissue has been removed by excimer laser irradiation. There was no case of via falsa. The simultaneous spectroscopic identification of the irradiated tissue provides a safe protection from overinstrumentation. First clinical trials on 20 patients suffering of chronical apical parodontitis have been carried out successfully.

  17. Controlled reshaping of the front surface of the cornea through its full-area ablation outside of the optical zone with a Gaussian ArF excimer laser beam

    International Nuclear Information System (INIS)

    We studied in vitro the response of the topography of the cornea to its full-area laser ablation (the laser beam spot diameter is commensurable with the size of the interface) outside of the central zone with an excimer laser having a Gaussian fluence distribution across the beam. Subject to investigation were the topographically controlled surface changes of the anterior cornea in 60 porcine eyes with a 5 ± 1.25-diopter artificially induced astigmatism, the changes being caused by laser ablation of the stromal collagen in two 3.5-mm-dia. circular areas along the weaker astigmatism axis. Experimental relationships are presented between the actual astigmatism correction and the expected correction for the intact optical zones 1, 2, 3, and 4 mm in diameter. The data for each zone were approximated by the least-squares method with the function d = a + bx. The coefficient b is given with the root-mean-square error. The statistical processing of the data yielded the following results: d = (0.14 ± 0.037)x for the 1-mm-dia. optical zone, (1.10 ± 0.036)x for the 2-mm-dia. optical zone, (1.04 ± 0.020)x for the 3-mm-dia. optical zone, and (0.55 ± 0.04)x for the 4-mm-dia. optical zone. Full astigmatism correction was achieved with ablation effected outside of the 3-mm-dia. optical zone. The surface changes of the cornea are shown to be due not only to the removal of the corneal tissue, but also to the biomechanical topographic response of the cornea to its strain caused by the formation of a dense pseudomembrane in the ablation area. (letter)

  18. Controlled reshaping of the front surface of the cornea through its full-area ablation outside of the optical zone with a Gaussian ArF excimer laser beam

    Science.gov (United States)

    Semchishen, A. V.; Semchishen, V. A.

    2014-01-01

    We studied in vitro the response of the topography of the cornea to its full-area laser ablation (the laser beam spot diameter is commensurable with the size of the interface) outside of the central zone with an excimer laser having a Gaussian fluence distribution across the beam. Subject to investigation were the topographically controlled surface changes of the anterior cornea in 60 porcine eyes with a 5 ± 1.25-diopter artificially induced astigmatism, the changes being caused by laser ablation of the stromal collagen in two 3.5-mm-dia. circular areas along the weaker astigmatism axis. Experimental relationships are presented between the actual astigmatism correction and the expected correction for the intact optical zones 1, 2, 3, and 4 mm in diameter. The data for each zone were approximated by the least-squares method with the function d = a + bx. The coefficient b is given with the root-mean-square error. The statistical processing of the data yielded the following results: d = (0.14 ± 0.037)x for the 1-mm-dia. optical zone, (1.10 ± 0.036)x for the 2-mm-dia. optical zone, (1.04 ± 0.020)x for the 3-mm-dia. optical zone, and (0.55 ± 0.04)x for the 4-mm-dia. optical zone. Full astigmatism correction was achieved with ablation effected outside of the 3-mm-dia. optical zone. The surface changes of the cornea are shown to be due not only to the removal of the corneal tissue, but also to the biomechanical topographic response of the cornea to its strain caused by the formation of a dense pseudomembrane in the ablation area.

  19. X-ray photoemission investigation of excimer laser induced etching of InP

    International Nuclear Information System (INIS)

    ArF excimer laser induced etching of InP in various etch gases (HBr, HCl, Cl2) is discussed with regard to its spatial resolution capability. X-ray photoemission spectra and large-area etch rate measurements published before lead to fundamental understanding and interpretation of the characteristics of etched test structures. HBr and HCl require gas phase photodissociation. Cl2, in contrast, has the advantage to react spontaneously

  20. Corneal topography of excimer laser photorefractive keratectomy.

    Science.gov (United States)

    Klyce, S D; Smolek, M K

    1993-01-01

    The application of the 193 nm excimer laser for keratorefractive surgery promises to deliver a higher degree of precision and predictability than traditional procedures such as radial keratotomy. The development and evaluation of keratorefractive surgery have benefited from the parallel advances made in the field of corneal topography analysis. We used the Computed Anatomy Topography Modeling System (TMS-1) to analyze a Louisiana State University (LSU) Eye Center series of patients who had photorefractive keratectomy for the treatment of myopia with the VISX Twenty/Twenty excimer laser system. The excimer ablations were characterized by a relatively uniform distribution of surface powers within the treated zone. In the few cases that exhibited marked refractive regression, corneal topography analysis showed correlative changes. With topographical analysis, centration of the ablations relative to the center of the pupil could be evaluated. Marked improvement in centration occurred in the patients of LSU Series IIB in which the procedure to locate the point on the cornea directly over the pupil's center during surgery was refined. Corneal topographical analysis provides objective measures of keratorefractive surgical results and is able to measure the precise tissue removal effect of excimer laser ablation without the uncertainties caused by measuring visual acuity alone. Our observations forecast the need for improved aids to center the laser ablations and for the development of a course of treatment to prevent post-ablation stromal remodeling. PMID:8450433

  1. Generation of intense 10-ps, 193-nm pulses using simple distributed feedback dye lasers and an ArF(*) amplifier.

    Science.gov (United States)

    Hatten, D L; Cui, Y; Iii, W T; Mikes, T; Goldhar, J

    1992-11-20

    A pair of holographic distributed feedback dye lasers is used to generate 10-ps pulses at two selected wavelengths that are mixed in a BBO crystal to produce a pulse ~ 10 ps in duration at 193 nm. This seed pulse is subsequently amplified in an ArF(*) excimer laser to an energy of 10-15 mJ with <40 microJ in amplified spontaneous emission. The pulses are nearly transform limited and diffraction limited. PMID:20802565

  2. Excimer laser-ablated plasma atomic spectrometry

    International Nuclear Information System (INIS)

    The characterization and evaluation of a new kind of excimer laser-ablated plasma and applications for direct spectrochemical analysis were investigated through time- and space-resolved spectroscopy. The shape, size, emission spectra, and excitation temperatures of the plasma are largely department on the atmospheric surroundings, the ambient gas composition, the pressure, and laser energy. Spatial discrimination may be desirable to increase the line-to-background (L/B) ratio in atomic emission spectroscopy. A direct spectrochemical analytical method for solid samples with good linearity was developed using the excimer laser-AES. The sensitivity of the analytical signal varied depending on the chemical matrix of the solid samples. A typical detection limit for potassium in a glass matrix was 0.13 μg/g.

  3. Discharge instabilities in high-pressure fluorine based excimer laser gas mixtures

    OpenAIRE

    Mathew, Denny

    2007-01-01

    Fluorine based excimer lasers such as KrF, ArF and F2 are currently the most powerful sources available in the ultraviolet wavelength range, operating at 248 nm, at 193 nm and at 157 nm, respectively. They are thus of central importance for numerous applications in this range. At these short wavelengths, reaching the laser threshold for an efficient operation, F2-based lasers require to be pumped, in a controlled manner, with very high power densities. This can practically be achieved only vi...

  4. Collateral damage-free debridement using 193nm ArF laser

    Science.gov (United States)

    Wynne, James J.; Felsenstein, Jerome M.; Trzcinski, Robert; Zupanski-Nielsen, Donna; Connors, Daniel P.

    2011-03-01

    Burn eschar and other necrotic areas of the skin and soft tissue are anhydrous compared to the underlying viable tissue. A 193 nm ArF excimer laser, emitting electromagnetic radiation at 6.4 eV at fluence exceeding the ablation threshold, will debride such necrotic areas. Because such radiation is strongly absorbed by aqueous chloride ions through the nonthermal process of electron photodetachment, debridement will cease when hydrated (with chloride ions) viable tissue is exposed, avoiding collateral damage to this tissue. Such tissue will be sterile and ready for further treatment, such as a wound dressing and/or a skin graft.

  5. Excimer laser irradiation of metal surfaces

    Science.gov (United States)

    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

  6. Excimer laser development for fusion

    International Nuclear Information System (INIS)

    The future utility of inertial confinement fusion requires a new driver. Successful experiments coupling laser energy to targets, and our understanding of fuel capsule behavior strongly suggest that a laboratory thermonuclear source is attainable and power production may be considered if a suitable driver with high efficiency, high repetition rate, and most importantly, low capital cost, can be identified. No adequate driver exists today; however, the krypton fluoride laser holds great promise. By the end of this decade, driver development can be brought to the point that a technically justifiable choice can be made for the future direction of ICF

  7. Electrodeless excimer laser; Laser a eccimeri senza elettrodi

    Energy Technology Data Exchange (ETDEWEB)

    Lisi, N. [ENEA, Divisione Nuovi Materiali, Centro Ricerche Casaccia, Rome (Italy)

    2001-07-01

    In this paper it is proposed how to build an excimer laser based on an electrodeless discharge (or Dielectric Barrier Discharge). Such laser could operate with a low energy per pulse (<100 mJ) and a high repetition rate (<100 kHz). The most relevant advantage an electrodeless DBD laser is the much longer gas mixture lifetime. This feature could allow the operation of a sealed laser emitting higher average power with respect to commercially available excimer lasers. Such discharge scheme could be advantageous in order to excite the F{sub 2} excimer molecule, whose emission wavelength in the VUV range (157 nm) at high reprate is particularly interesting in the micro-lithography field. [Italian] In questo documento viene proposto come costruire un laser a eccimeri basato su una scarica priva di elettrodi, o Dielectric Barrier Discharge. Tale laser puo' funzionare con una bassa energia per impulso (<100 mJ) ad alta frequenza di ripetizione (<100 kHz). Il vantaggio fondamentale di un laser a DBD e quindi privo di elettrodi e' la vita media della miscela gassosa molto piu' alta che potrebbe permettere alla camera laser di operare sigillata ad una potenza media superiore a quella dei laser a eccimeri attuali. Tale schema di pompaggio potrebbe essere particolarmente vantaggioso per eccitare la molecola eccimero F{sub 2} la cui lunghezza di emissione nel VUV (157 nm) ad elevata frequenza di ripetizione presenta un notevole interesse nel campo della produzione di microcircuiti.

  8. Excimer laser annealing for low-voltage power MOSFET

    Science.gov (United States)

    Chen, Yi; Okada, Tatsuya; Noguchi, Takashi; Mazzamuto, Fulvio; Huet, Karim

    2016-08-01

    Excimer laser annealing of lumped beam was performed to form the P-base junction for high-performance low-voltage-power MOSFET. An equivalent shallow-junction structure for the P-base junction with a uniform impurity distribution is realized by adopting excimer laser annealing (ELA). The impurity distribution in the P-base junction can be controlled precisely by the irradiated pulse energy density and the number of shots of excimer laser. High impurity activation for the shallow junction has been confirmed in the melted phase. The application of the laser annealing technology in the fabrication process of a practical low-voltage trench gate MOSFET was also examined.

  9. Irradiation experiment of textile materials by excimer laser pulses

    International Nuclear Information System (INIS)

    The results of the irradiation experiment of natural and synthetic textile materials by XeCl (excimer) laser pulses (emission wavelenght λ=0.308 μm) are presented. The friction, finish and look variations of the irradiated textiles are examined as a function of the laser radiation parameters (e. g. fluence and shots number). The possibility of using excimer laser systems on industrial bases is also discussed

  10. Fabrication of SERS Active Surface on Polyimide Sample by Excimer Laser Irradiation

    Directory of Open Access Journals (Sweden)

    T. Csizmadia

    2014-01-01

    Full Text Available A possible application of excimer laser irradiation for the preparation of surface enhanced Raman spectroscopy (SERS substrate is demonstrated. A polyimide foil of 125 μm thickness was irradiated by 240 pulses of focused ArF excimer laser beam (λ = 193 nm, FWHM = 20 ns. The applied fluence was varied between 40 and 80 mJ/cm2. After laser processing, the sample was coated with 40 nm silver by PLD in order to create a conducting layer required for the SERS application. The SERS activity of the samples was tested by Raman microscopy. The Raman spectra of Rhodamine 6G aqueous solution (c=10−3 mol/dm3 were collected from the patterned and metalized areas. For areas prepared at 40–60 mJ/cm2 laser fluences, the measured Raman intensities have shown a linear dependence on the applied laser fluence, while above 60 mJ/cm2 saturation was observed. The morphology of the SERS active surface areas was investigated by scanning electron microscopy. Finite element modeling was performed in order to simulate the laser-absorption induced heating of the polyimide foil. The simulation resulted in the temporal and spatial distribution of the estimated temperature in the irradiated polyimide sample, which are important for understanding the structure formation process.

  11. The Excimer Laser: Its Impact on Science and Industry

    Science.gov (United States)

    Basting, Dirk

    2010-03-01

    After the laser was demonstrated in 1960, 15 years were required to develop a practical method for extending laser emission into the UV: the Excimer laser. This historical review will describe the challenges with the new medium and provide an insight into the technological achievements. In the transition from Science to Industry it will be shown how start-ups successfully commercialized laboratory prototypes. The pioneers in this rapidly expanding field will be identified and the influence of government-funded research as well as the role of venture capital will be discussed. In scientific applications, the fields of photochemistry and material research were particularly stimulated by the advent of a reliable UV light source. Numerous industrial applications and worldwide research in novel applications were fueled In the early and mid 80's by progress in excimer laser performance and technology. The discovery of ablative photocomposition of polymer materials by Srinivasan at IBM opened the door to a multitude of important excimer applications. Micromachining with extreme precision with an excimer laser enabled the success of the inkjet printer business. Biological materials such as the human cornea can also be ``machined'' at 193nm, as proposed in 1983 by Trokel and Srinivasan. This provided the foundation of a new medical technology and an industry relying on the excimer laser to perform refractive surgery to correct vision Today, by far the largest use of the excimer laser is in photolithography to manufacture semiconductor chips, an application discovered by Jain at IBM in the early 80's. Moore's law of shrinking the size of the structure to multiply the number of transistors on a chip could not have held true for so long without the deep UV excimer laser as a light source. The presentation will conclude with comments on the most recent applications and latest market trends.

  12. Perspectives of using the 223-nm wavelength of the KrCl excimer laser for refractive surgery and for the treatment of some eye diseases

    Science.gov (United States)

    Bagayev, Sergei N.; Chernikh, Valery V.; Razhev, Alexander M.; Zhupikov, Andrey A.

    2000-06-01

    The new surgical UV ophthalmic laser system Medilex based on the KrCl (223 nm) excimer laser for refractive surgery was created. The comparative analysis of using the UV ophthalmic laser systems Medilex based on the ArF (193 nm) and the KrCl (223 nm) excimer lasers for the correction of refractive errors was performed. The system with the radiation wavelength of 223 nanometer of the KrCl excimer laser for refractive surgery was shown to have several medical and technical advantages over the system with the traditionally used radiation wavelength of 193 nanometer of the ArF excimer laser. In addition the use of the wavelength of 223 nanometer extends functional features of the system, allowing to make not only standard for this type systems surgical and therapeutic procedures but also to treat such ocular diseases as the glaucoma and herpetic keratities. For the UV ophthalmic laser systems Medilex three variations of the beam delivery system including special rotating masks and different beam homogenize systems were developed. All created beam delivery systems are able to make the correction of myopia, hyperopia, astigmatism and myopic or hyperopic astigmatism and may be used for therapeutic procedures. The results of the initial treatments of refractive error corrections using the UV ophthalmic laser systems Medilex for both photorefractive keratectomy (PRK) and LASIK procedures are presented.

  13. Formation of color centers in a soda-lime silicate glass by excimer laser irradiation

    International Nuclear Information System (INIS)

    We have investigated defect generation in soda-lime silicate and iron-doped soda-lime silicate glasses by excimer laser irradiation in order to apply coloration due to radiation-induced defects as a coloring technique for practical glass products. The laser irradiation generated various kinds of defects, i.e., non-bridging oxygen hole centers (NBOHCs), E' centers, and trapped electron centers, as does x-ray and γ-ray irradiation. The amounts of generated NBOHCs, monitored by the absorption intensity, increased at first with the irradiation time for both the ArF and XeF lasers, and eventually became saturated. The saturated values for the ArF laser irradiation were almost the same regardless of the laser intensity, whereas those for the XeF laser irradiation were dependent on the intensity; a higher intensity generated a larger amount of NBOHCs. From the comparison of the energies of the photon and the absorption edge of the soda-lime silicate glasses, the defect generation reactions were expected to be one-photon and two-photon processes for the ArF and XeF lasers, respectively. In order to explain the defect generation behavior, we used a simple kinetic model in which the NBOHCs are reversibly generated and annihilated through the photo-reaction. The model includes a stretched exponential function, which is often observed for reactions occurring in amorphous materials. The dependences of the amounts of the generated NBOHCs on the irradiation time and intensity of the laser pulses derived from the model were consistent with the experimental results.

  14. Analysis of the influence of substrate temperature on hydroxyapatite deposited by laser ablation method using ArF laser

    Science.gov (United States)

    Mróz, Waldemar; Jedyński, Marcin; Szymański, Zygmunt; Prokopiuk, Artur; Burdyńska, Sylwia

    2007-02-01

    Hydroxyapatite layers (Ca 10(PO 4)6(OH) II) were deposited by means of laser ablation method using an ArF excimer laser (193 nm). The influence of substrate temperature on the structure of deposited layers was studied. The layers were deposited on Ti6Al4V titanium alloy which temperature varied from 250 °C to 700 °C. The characteristics of the hydroxyapatite coatings were determined by means of Fourier Transform Infrared spectroscopy (FTIR). The obtained spectra reveal that the presence and abundance of the PO 4 absorption bands depend on the substrate temperature. The topography of the deposited layers were analyzed with the use of an Atomic Force Microscope.

  15. Femtosecond ultraviolet (248 nm) excimer laser processing of Teflon (PTFE)

    International Nuclear Information System (INIS)

    We have investigated by X-ray photoelectron spectroscopy (XPS) the surface of poly(tetrafluoroethylene) (PTFE) films, which were subjected to processing by femtosecond (fs) UV radiation from an excimer laser (KrF: λ=248 nm, tp∼380 fs) in air. Bulk characterization of processed PTFE films by Fourier transform infrared spectroscopy (FTIR) permit an investigation of the laser induced modifications in the material at energy densities below the ablation threshold. No features in XPS and FTIR spectra indicated the incorporation of hydrogen and/or oxygen, or the formation of a cross-linked network of carbon indicating chemically clean processing in contrast to nanosecond excimer laser processing which chemically degrades the surface. Scanning electron microscopy (SEM) of the micrometer size vertical interconnect (microvia) indicated mechanically and thermally damage free processing of PTFE with good edge quality, in contrast to nanosecond excimer laser processing

  16. Overview on the high power excimer laser technology

    Science.gov (United States)

    Liu, Jingru

    2013-05-01

    High power excimer laser has essential applications in the fields of high energy density physics, inertial fusion energy and industry owing to its advantages such as short wavelength, high gain, wide bandwidth, energy scalable and repetition operating ability. This overview is aimed at an introduction and evaluation of enormous endeavor of the international high power excimer laser community in the last 30 years. The main technologies of high power excimer laser are reviewed, which include the pumping source technology, angular multiplexing and pulse compressing, beam-smoothing and homogenous irradiation, high efficiency and repetitive operation et al. A high power XeCl laser system developed in NINT of China is described in detail.

  17. Optical design of high power excimer laser system

    International Nuclear Information System (INIS)

    Image relay and angular multiplexing,which should be considered together in the design of high power excimer laser system, is reviewed. It's important to select proper illumination setup and laser beam shaping techniques. Given the complex and special angular multiplexing scheme in high power excimer laser systems, some detailed conceptual layout schemes are given in the paper. After a brief description of lens array and reflective telescope objective, which combine the incoming beams to a common focus, a new schematic layout which uses the final targeting optics and one optical delay line array, to realize multiplexing and de-multiplexing simultaneously is first proposed in the paper. (authors)

  18. Cleaning of large area by excimer laser ablation

    Science.gov (United States)

    Sentis, Marc L.; Delaporte, Philippe C.; Marine, Wladimir I.; Uteza, Olivier P.

    2000-01-01

    Surface removal technologies are being challenged from environmental and economic perspectives. This paper is concerned with laser ablation applied to large surface cleaning with an automatized excimer laser unit. The study focused on metallic surfaces that are oxidized and are representative of contaminated surfaces with radionuclides in a context of nuclear power plant maintenance. The whole system is described: laser, beam deliver, particle collection cell, real time control of cleaning processes. Results concerning surface laser interaction and substrate modifications are presented.

  19. New excimer laser technique for the correction of strabismus and diplopia

    Science.gov (United States)

    Azar, Dimitri T.

    1994-06-01

    We used the ArF excimer laser to determine the feasibility of performing prismatic photoablations in model eyes (plastic spheres simulating the eye), and in rabbit corneas. This would correct diplopia and small angles of deviation, and result in minimal refractive alterations. We modified excimer laser delivery system that achieved the desired corneal contour of prismatic ablations. 193-nm argon fluoride laser was used at fluence of 160 mJ/cm2 and ablation rate 5 Hz. 5.0-mm diameter, 40 um corneal epithelial ablation were followed by 5.0- mm diameter, prismatic photokeratectomy (PPK). We were able to achieve prismatic photoablation of PMMA blocks and lenses. No other refractive changes accompanied the prismatic photoablation of PMMA blocks and lenses. No other refractive changes accompanied the prismatic effect. In rabbits re-epithelialization of the 5-mm ablations was complete by day 3, and corneal haze was not observed by gross examination. Epithelial hyperplasia and subepithelial scarring were noted at the deep edges. PPK holds important therapeutic potential for fine-tuning results of conventional strabismus surgery, and for patients with stable diplopia following nerve palsy and ocular surgery.

  20. Treatment of onychomycosis using radiation of excimer laser

    Czech Academy of Sciences Publication Activity Database

    Urzová, J.; Jelínek, Miroslav; Mikšovský, Jan; Kymplová, J.

    2013-01-01

    Roč. 647, JAN (2013), s. 636-641. ISSN 1022-6680 R&D Projects: GA MŠk LD12069 Institutional support: RVO:68378271 Keywords : excimer laser * UV-C radiation * nails * onychomycosis Subject RIV: BM - Solid Matter Physics ; Magnetism

  1. Subjective results of excimer laser correction of myopia. Review

    OpenAIRE

    V. N. Trubilin; S. Yu. Shchukin

    2014-01-01

    In review presents data of various authors regarding the subjective results excimer laser correction of myopia by LASIK. It was revealed that a group of patients with a high degree of dissatisfaction amounts to 4.6% of the total in all studies. High subjective results are confirmed by the positive dynamics of the «quality of life» of the patient.

  2. Assessment of the suitability of excimer lasers in treating onychomycosis

    Czech Academy of Sciences Publication Activity Database

    Kymplová, J.; Jelínek, Miroslav; Urzová, J.; Mikšovský, Jan; Dušek, K.; Bauerová, L.

    Vol. 497. Bristol : IOP Publishing Ltd, 2014, "012022-1"-"012022-13". ISSN 1742-6588. - (497). [International Laser Physics Workshop /22./ (LPHYS'13). Praha (CZ), 15.07.2013-19.07.2013] R&D Projects: GA ČR GA13-33056S Institutional support: RVO:68378271 Keywords : excimer laser * UV-C radiation * nails * onychomycosis Subject RIV: BM - Solid Matter Physics ; Magnetism

  3. Surface modification of polymer materials by excimer-laser irradiation

    International Nuclear Information System (INIS)

    The surface modification of fluoropolymers was studied with intense UV radiations from excimer lasers. The adhesive strength of polytetrafluoroethylene film was enhanced remarkably by KrF-laser irradiation in air when a small amount of aromatic compounds was blended. Tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer was endowed with the high wettability by ArF-laser irradiation in water dissolved carbon monoxide. The enhancement of the wettability was closely related to the decrease of the fluorine/carbon atomic ratio and the increase of the oxygen/carbon ratio. (author)

  4. Subjective results of excimer laser correction of myopia. Review

    Directory of Open Access Journals (Sweden)

    V. N. Trubilin

    2014-07-01

    Full Text Available In review presents data of various authors regarding the subjective results excimer laser correction of myopia by LASIK. It was revealed that a group of patients with a high degree of dissatisfaction amounts to 4.6% of the total in all studies. High subjective results are confirmed by the positive dynamics of the «quality of life» of the patient.

  5. Subjective results of excimer laser correction of myopia. Review

    Directory of Open Access Journals (Sweden)

    V. N. Trubilin

    2012-01-01

    Full Text Available In review presents data of various authors regarding the subjective results excimer laser correction of myopia by LASIK. It was revealed that a group of patients with a high degree of dissatisfaction amounts to 4.6% of the total in all studies. High subjective results are confirmed by the positive dynamics of the «quality of life» of the patient.

  6. Assessment of the suitability of excimer lasers in treating onychomycosis

    International Nuclear Information System (INIS)

    Since it is known that UV-C radiation kills fungus, we wanted to verify the hypothesis that the use of excimer laser could be an alternative method for treating onychomycosis - nail fungus. The aim of the first stage of this work was to determine the transmission, reflection and absorption of nails. In the following stage we focused on irradiation of fungi. Our final task is to assess whether it is possible to determine the parameters of radiation (a total dose,a dose per pulse frequency, a repetition rate, a number of pulses) for which the elimination of fungi would be the most effective but without damaging the nail and soft tissue underneath it. The results so far have showed that UV-C radiation does not pass through a fingernail to such an extent that it could damage the soft tissue beneath it. Fungi are destroyed by the application of only small doses of radiation using the excimer laser. Additional measurements will be required to determine the modulation parameters of the excimer laser radiation for the treatment of onychomycosis.

  7. Assessment of the Suitability of Excimer Lasers in Treating Onychomycosis

    Science.gov (United States)

    Kymplová, Jaroslava; Jelínek, Miroslav; Urzová, Jana; Mikšovský, Jan; Dušek, Karel; Bauerová, Lenka

    2014-04-01

    Since it is known that UV-C radiation kills fungus, we wanted to verify the hypothesis that the use of excimer laser could be an alternative method for treating onychomycosis - nail fungus. The aim of the first stage of this work was to determine the transmission, reflection and absorption of nails. In the following stage we focused on irradiation of fungi. Our final task is to assess whether it is possible to determine the parameters of radiation (a total dose,a dose per pulse frequency, a repetition rate, a number of pulses) for which the elimination of fungi would be the most effective but without damaging the nail and soft tissue underneath it. The results so far have showed that UV-C radiation does not pass through a fingernail to such an extent that it could damage the soft tissue beneath it. Fungi are destroyed by the application of only small doses of radiation using the excimer laser. Additional measurements will be required to determine the modulation parameters of the excimer laser radiation for the treatment of onychomycosis.

  8. PTTL method applied to UV radiation detection during refractive surgery using excimer laser

    International Nuclear Information System (INIS)

    The method of photo-transferred thermoluminescence (PTTL), using CaSO4:Dy pellets produced at IPEN as sensitive material, was used to detect the spread laser radiation inside the surgery room during refractive surgical procedures using ArF excimer lasers. The purpose of this work was to study the viability of performing the ultraviolet radiation (UVR) exposure detection of patients and the hospital's surgical staff during a refractive surgery. The CaSO4:Dy pellets were positioned at different distances from the laser source inside the surgery room: patient's (≅0.15 m), surgeon's (≅0.5 m) and nurse's (≅1.0 m) foreheads, lateral (≅1.5 m) and back (≅4.0 m) walls. The measurements of PTTL were carried out at two different conditions: five surgeries, each one taking ∼10 min, and during a period of 4 h (cumulative), when several operations were performed. The detectors positioned as far as 4.0 m from the UV laser source were sensitised, making the UVR detection feasible at large source-detector distances. The absorbed energy was detected in the range from 40 μJ to 30 mJ during a surgery. This result indicates that the method studied can be used to detect the spread UVR. (authors)

  9. Studies in fiber guided excimer laser surgery for cutting and drilling bone and meniscus

    OpenAIRE

    Dressel, Martin; Jahn, Renate; Neu, Walter; Jungbluth, Karl-Heinz

    1991-01-01

    Our experiments on transmitting high-power excimer laser pulses through optical fibers and our investigations on excimer laser ablation of hard tissue show the feasibility of using the excimer laser as an additional instrument in general and accident surgery involving minimal invasive surgery. By combining XeCl-excimer lasers and tapered fused silica fibers we obtained output fluences up to 32 J/cm2 and ablation rates of 3 m/pulse of hard tissue. This enables us to cut bone and cartilage in a...

  10. Automatic alignment of double optical paths in excimer laser amplifier

    Science.gov (United States)

    Wang, Dahui; Zhao, Xueqing; Hua, Hengqi; Zhang, Yongsheng; Hu, Yun; Yi, Aiping; Zhao, Jun

    2013-05-01

    A kind of beam automatic alignment method used for double paths amplification in the electron pumped excimer laser system is demonstrated. In this way, the beams from the amplifiers can be transferred along the designated direction and accordingly irradiate on the target with high stabilization and accuracy. However, owing to nonexistence of natural alignment references in excimer laser amplifiers, two cross-hairs structure is used to align the beams. Here, one crosshair put into the input beam is regarded as the near-field reference while the other put into output beam is regarded as the far-field reference. The two cross-hairs are transmitted onto Charge Coupled Devices (CCD) by image-relaying structures separately. The errors between intersection points of two cross-talk images and centroid coordinates of actual beam are recorded automatically and sent to closed loop feedback control mechanism. Negative feedback keeps running until preset accuracy is reached. On the basis of above-mentioned design, the alignment optical path is built and the software is compiled, whereafter the experiment of double paths automatic alignment in electron pumped excimer laser amplifier is carried through. Meanwhile, the related influencing factors and the alignment precision are analyzed. Experimental results indicate that the alignment system can achieve the aiming direction of automatic aligning beams in short time. The analysis shows that the accuracy of alignment system is 0.63μrad and the beam maximum restoration error is 13.75μm. Furthermore, the bigger distance between the two cross-hairs, the higher precision of the system is. Therefore, the automatic alignment system has been used in angular multiplexing excimer Main Oscillation Power Amplification (MOPA) system and can satisfy the requirement of beam alignment precision on the whole.

  11. Boron doping of silicon using excimer lasers

    International Nuclear Information System (INIS)

    The use of lasers in the doping of semiconductors has been investigated extensively these last years both for photovoltaic and microelectronic applications. In this work, doping of single-crystal silicon in BCl3 ambients using a pulsed UV laser has been studied as a function of laser wavelength and fluence in order to investigate the effects of photochemical decomposition of the BCl3 gas and the effects of thermal decomposition of adsorbed layers on the doping process. Different parameters involved in the process (laser energy density, number of pulses per frame, BCl3 gas pressure) were investigated. The electrical characteristics of the doped layers are discussed

  12. Influence of the laser wavelength on the epitaxial growth and electrical properties of La0.8Sr0.2MnO3 films grown by excimer laser-assisted MOD

    International Nuclear Information System (INIS)

    Epitaxial La1-xSrxMnO3 (LSMO) films were prepared by excimer laser-assisted metal organic deposition (ELAMOD) at a low temperature using ArF, KrF, and XeCl excimer lasers. Cross-section transmission electron microscopy (XTEM) observations confirmed the epitaxial growth and homogeneity of the LSMO film on a SrTiO3 (STO) substrate, which was prepared using ArF, KrF, and XeCl excimer lasers. It was found that uniform epitaxial films could be grown at 500 deg. C by laser irradiation. When an XeCl laser was used, an epitaxial film was formed on the STO substrate at a fluence range from 80 to 140 mJ/cm2 of the laser fluence for the epitaxial growth of LSMO film on STO substrate was changed. When the LaAlO3 (LAO) substrate was used, an epitaxial film was only obtained by ArF laser irradiation, and no epitaxial film was obtained using the KrF and XeCl lasers. When the back of the amorphous LSMO film on an LAO substrate was irradiated using a KrF laser, no epitaxial film formed. Based on the effect of the wavelength and substrate material on the epitaxial growth, formation of the epitaxial film would be found to be photo thermal reaction and photochemical reaction. The maximum temperature coefficient of resistance (TCR) of the epitaxial La0.8Sr0.2MnO3 film on an STO substrate grown using an XeCl laser is 4.0%/K at 275 K. XeCl lasers that deliver stabilized pulse energies can be used to prepare LSMO films with good a TCR.

  13. Pixel diamond detectors for excimer laser beam diagnostics

    Science.gov (United States)

    Girolami, M.; Allegrini, P.; Conte, G.; Salvatori, S.

    2011-05-01

    Laser beam profiling technology in the UV spectrum of light is evolving with the increase of excimer lasers and lamps applications, that span from lithography for VLSI circuits to eye surgery. The development of a beam-profiler, able to capture the excimer laser single pulse and process the acquired pixel current signals in the time period between each pulse, is mandatory for such applications. 1D and 2D array detectors have been realized on polycrystalline CVD diamond specimens. The fast diamond photoresponse, in the ns time regime, suggests the suitability of such devices for fine tuning feedback of high-power pulsed-laser cavities, whereas solar-blindness guarantees high performance in UV beam diagnostics, also under high intensity background illumination. Offering unique properties in terms of thermal conductivity and visible-light transparency, diamond represents one of the most suitable candidate for the detection of high-power UV laser emission. The relatively high resistivity of diamond in the dark has allowed the fabrication of photoconductive vertical pixel-detectors. A semitransparent light-receiving back-side contact has been used for detector biasing. Each pixel signal has been conditioned by a multi-channel read-out electronics made up of a high-sensitive integrator and a Σ-Δ A/D converter. The 500 μs conversion time has allowed a data acquisition rate up to 2 kSPS (Sample Per Second).

  14. Plasma plume induced during ArF laser ablation of hydroxyapatite

    International Nuclear Information System (INIS)

    Plasma plume induced by ArF excimer laser ablation of a hydroxyapatite (Ca10(PO4)6(OH)2) target was studied during expansion into a vacuum or water vapour. The ArF laser operated at a wavelength of 193 nm with a pulse energy of 300-350 mJ and a 20 ns pulse duration. The emission spectra of the plasma plume were registered with the use of a spectrograph and an ICCD camera. The expansion of the plasma plume was studied using the time of flight method. The time-dependent radiation of the Ca I and Ca II lines was registered with the use of a monochromator and photomultiplier at various distances from the target. The dynamics of the plasma plume was also imaged by means of fast photography. It was found that during expansion into a vacuum, the plasma front moved with a constant velocity of 1.75 x 104 m s-1, while in the case of ambient water vapour at a pressure of 20 Pa, velocities of 1.75 x 104-1.5 x 103 m s-1 were found depending on the distance from the target. Electron densities of 1.2 x 1024-4.5 x 1021 m-3 were determined from the Stark broadening of the Ca II and Ca I lines at distances of 1-25 mm from the target. Temperatures of 11,500-4500 K were determined from the relative intensities of carbon lines and continuum radiation at distances of 4-29 mm from the target. The results allowed the estimation of thermal and kinetic energies of ablated particles. During expansion into a vacuum, the kinetic energies of Ca, P and O atoms were 64, 49 and 25 eV, respectively. During expansion into water vapour, kinetic energies dropped to 0.47, 0.36 and 0.19 eV, respectively at a distance of 25 mm from the target and were comparable to the energies of thermal motion.

  15. The Characteristics of the Surface Topography of Excimer Laser Processed Al2O3 Ceramic

    Institute of Scientific and Technical Information of China (English)

    LIUYing; WENShi-zhu

    2004-01-01

    Surface of Al2O3 ceramic was processed by an excimer laser and the characteristics of topography were examined based on the application of thesystem(MEMS). It is indicated that the statistic pararueters of surface topography processed by the excimer laser have an obvioas regularity. The arithmeticmean value Ro and the root-mean square value Rq change with the changing of processing parameters in the same step and trend, and there is a quantitative relation between them. A simplified nuuIel is proposed for the excimer laser processing surface profile, whose results of the analysis and calculation agree basically with the experimental data. Furthermore, the surfaces processed by excimer laser are greatly fiat. Skewness root-mean-square value Zq changed little with the change of the technological parameters. The above characteristics depend on the processing principle of excimer laser, quite different from the cutting processing.

  16. Study on pulsed excimer laser deposited films

    CERN Document Server

    Liu Jing Ru; Li Tie Jun; Yao Dong Sheng; Wang Li Ge; Yuan Xiao; Wang Sheng; Ye Xi Sheng

    2002-01-01

    Pulsed lasers of two different durations (30 ns, 500 fs) are used to deposit Hydrogen-free Diamond Like Carbon (DLC) films over large areas. Analysis of DLC films shows remarkable mechanical, optical, electrical, and chemical properties that are close to those of diamond. By optical emission spectroscopy and ion probe, the effects of plasma characteristic on DLC film are on experimentally studied. Amorphous silicon films deposited by PLD are also experimentally studied

  17. Laser dentistry: A new application of excimer laser in root canal therapy

    International Nuclear Information System (INIS)

    We report the first study of the application of excimer lasers in dentistry for the treatment of dental root canals. High-energy ultraviolet (UV) radiation emitted by an XeCl excimer laser (308 nm) and delivered through suitable optical fibers can be used to remove residual organic tissue from the canals. To this aim, UV ablation thresholds of dental tissues have been measured, showing a preferential etching of infiltrated dentin in respect to healthy dentin, at laser fluences of 0.5-1.5 J/cm2. This technique has been tested on extracted tooth samples, simulating a clinical procedure. Fibers of decreasing core diameters have been used to treat different sections of the root canal down to its apical portion, resulting in an effective, easy, and fast cleaning action. Possible advantages of excimer laser clinical applications in respect to usual procedures are also discussed

  18. Excimer Laser Beam Analyzer Based on CVD Diamond

    Science.gov (United States)

    Girolami, Marco; Salvatori, Stefano; Conte, Gennaro

    2010-11-01

    1-D and 2-D detector arrays have been realized on CVD-diamond. The relatively high resistivity of diamond in the dark allowed the fabrication of photoconductive "sandwich" strip (1D) or pixel (2D) detectors: a semitransparent light-receiving back-side contact was used for detector biasing. Cross-talk between pixels was limited by using intermediate guard contacts connected at the same ground potential of the pixels. Each pixel photocurrent was conditioned by a read-out electronics composed by a high sensitive integrator and a Σ-Δ ADC converter. The overall 500 μs conversion time allowed a data acquisition rate up to 2 kSPS. The measured fast photoresponse of the samples in the ns time regime suggests to use the proposed devices for fine tuning feedback of high-power pulsed-laser cavities, whereas solar-blindness guarantees high performance in UV beam diagnostics also under high intensity background illumination. Offering unique properties in terms of thermal conductivity and visible-light transparency, diamond represents one of the most suitable candidate for the detection of high-power UV laser emission. The technology of laser beam profiling is evolving with the increase of excimer lasers applications that span from laser-cutting to VLSI and MEMS technologies. Indeed, to improve emission performances, fine tuning of the laser cavity is required. In such a view, the development of a beam-profiler, able to work in real-time between each laser pulse, is mandatory.

  19. Single photon excimer laser photodissociation of highly vibrationally excited polyatomic molecules

    International Nuclear Information System (INIS)

    The ir + uv photodissociation of SF6 has been performed using CO2 and ArF lasers. The two-color photolysis significantly enhances the photodissociation process over ArF irradiation alone and is found to preserve the initial isotopic specificity of the ir excitation process

  20. The application of excimer lasers for corneal sculpturing

    International Nuclear Information System (INIS)

    Of the broad selection of lasers available for surgery, the argon fluoride excimer laser offers a set of attributes that make it uniquely suited for the removal of corneal tissue. With ultraviolet radiation at 193mm, the energy of an individual photon (6.3 electron volts) is sufficient to break bonds in protein molecules without generating molecular vibration (heat). A single laser pulse is capable of removing 0.25 microns of corneal tissue over a well defined area 80 mm2 in extent. This excision with a lateral precision to a fraction of a micron causes no discernible damage to neighboring cells. The smooth surface left after the tissue is removed promotes a quick and predictable regrowth of the epithelium. The penetration of radiation into the underlying tissue is the order of a micron so there is no potential harm to the lens or retinal tissue. Insignificant mutagenesis or unscheduled DNA synthesis has been detected as a result of tissue irradiation at this wavelength. In the past few years major progress has been made towards developing ophthalmic procedures which utilize the unique properties of this laser. To date there are FDA IDE's (Investigational Device Exemptions) for the following procedures: Photorefractive Keratectomy (PRK) or corneal reshaping for correcting near-sightedness, far-sightedness and astigmatism without the need for eye glasses, contact lenses or conventional refractive surgery (Radial Keratotomy); Partial Excimer Trabeculectomy for relieving the pressure build-up caused by glaucoma; T-Excisons for reducing astigmatism; Myopic Keratomileusis (MKM) for the refractive correction of severe myopia; superficial Keratectomy (corneal smoothing) for treating various corneal scars, dystrophies, recurrent corneal erosion etc. In this paper the fundamentals of beam tissue interaction at 193nm will be discussed

  1. Excimer Laser Used as a Materials Characterization Tool: Sulphide Inclusion Printing in Steel

    OpenAIRE

    McIntosh, J.; Zervaki, A.; K. Papadimitriou; Haidemenopoulos, G. N.; Manousaki, A.; Zergioti, G.; Hontzopoulos, E.

    1993-01-01

    An application of the excimer laser in the area of material characterization making use of its ablative ability to perform surface sulphur printing is presented. It is shown that the differential ablative and surface melting capability of the excimer laser is useful in microetching sulphide inclusions in flat polished steel samples and rough fracture surfaces. An optimum laser fluence is found to be that which melts the sulphide particles without significant melting of the steel matrix or cau...

  2. Liquid crystal alignment on excimer laser irradiated polyimide

    International Nuclear Information System (INIS)

    Grating and photoinduced anisotropic modifications are made to polyimide layers to promote homogeneous and pretilted nematic liquid crystal alignment. Gratings are etched into the polyimide by irradiating a phase mask of period 1.1 μm with the output from a KrF excimer laser of wavelength 248 nm with fluences above the threshold required for ablation. Grating depths from 10 to 190 nm have been achieved using a simple pulse from the laser, and the liquid crystal azimuthal anchoring energy is determined as a function of the grating depth. Values up to 1.3 x 10-5 Jm-2 are found. Discrepancies are found when comparisons are made between experimental data and a theory based upon elastic strain energy minimisation. A modified theory taking finite polar anchoring into account shows better agreement. Polarised excimer laser radiation at normal incidence is used to induce an anisotropy which gives rise to homogeneous liquid crystal alignment. The strength of the azimuthal anchoring energy is similar to that produced by grating alignment. Spectroscopic analysis reveals that the alignment originates from the stronger depletion of polyimide chains parallel to the exposure polarisation direction. The dependence of beam fluence and exposure time on the anchoring energy is measured, and the degradation mechanism of the polyimide is investigated as a function of the exposure. We find that oxidative degradation takes place. We also use these techniques to identify the chemical composition of the polyimide material. Pretilted liquid crystal alignment has also been achieved, with pretilt angles up to 3.7 deg. A tilted polymer distribution is generated by oblique exposure of the polyimide to an elliptically polarised beam. We measure the liquid crystal pretilt angle as a function of the angle of incidence, and exposure time and present a theoretical analysis of the polyimide chain azimuthal distribution which agrees with the experimental results. Finally, a simple and novel technique

  3. Infrared recombination lasers pumped by low energy Nd: YAG and excimer lasers

    OpenAIRE

    Momma, C.; Hube, M.; Tünnermann, A.; Mossavi, K.; Wellegehausen, B.

    1992-01-01

    24 infrared laser lines on atomic and ionic transitions have been observed in recombining plasmas by vaporizing and ionizing Cd, Pb, Sn, Zn, and Mg with low energy Nd:YAG or excimer pump-lasers. For operation and optimization of the recombination lasers separated plasma spots and a plasma confinement have been used. The operation of shorter wavelength systems by isoelectronic scaling is discussed.

  4. Results of excimer-laser-performed photorefractive keratectomy operations

    Science.gov (United States)

    Ferincz, Istvan E.; Ratkay-Traub, Imola; Dinnyes, Maria

    1998-08-01

    We have performed excimer laser photorefractive keratectomy operations with a Schwind Keratom 2F to correct near- sightedness. 613 eyes of 348 patients were treated by this ablation method. We have selected 318 case, where the follow-up was at least 6 months long. The intended corrections were in the range of -1.75 D to -9.0 D for myopia. The optical zones were 5.5 and 6.0 mm. We present various results of the treatments: change of visual acuity, residual spherical refractive error, time valuation of healing, and ablation speed. We have found that the ablation speed of human cornea is depends on the age of patients. An equation is also presented to describe the relation between age and ablation speed.

  5. Nickel-disilicide-assisted excimer laser crystallization of amorphous silicon

    Institute of Scientific and Technical Information of China (English)

    Liao Yan-Ping; Shao Xi-Bin; Gao Feng-Li; Luo Wen-Sheng; Wu Yuan; Fu Guo-Zhu; Jing Hai; Ma Kai

    2006-01-01

    Polycrystalline silicon (poly-Si) thin film has been prepared by means of nickel-disilicide (NiSi2) assisted excimer laser crystallization (ELC). The process to prepare a sample includes two steps. One step consists of the formation of NiSi2 precipitates by heat-treating the dehydrogenated amorphous silicon (a-Si) coated with a thin layer of Ni. And the other step consists of the formation of poly-Si grains by means of ELC. According to the test results of scanning electron microscopy (SEM), another grain growth model named two-interface grain growth has been proposed to contrast with the conventional Ni-metal-induced lateral crystallization (Ni-MILC) model and the ELC model. That is, an additional grain growth interface other than that in conventional ELC is formed, which consists of NiSi2 precipitates and a-Si.The processes for grain growth according to various excimer laser energy densities delivered to the a-Si film have been discussed. It is discovered that grains with needle shape and most of a uniform orientation are formed which grow up with NiSi2 precipitates as seeds. The reason for the formation of such grains which are different from that of Ni-MILCwithout migration of Ni atoms is not clear. Our model and analysis point out a method to prepare grains with needle shape and mostly of a uniform orientation. If such grains are utilized to make thin-film transistor, its characteristics may be improved.

  6. Studies in fiber guided excimer laser surgery for cutting and drilling bone and meniscus.

    Science.gov (United States)

    Dressel, M; Jahn, R; Neu, W; Jungbluth, K H

    1991-01-01

    Our experiments on transmitting high-power excimer laser pulses through optical fibers and our investigations on excimer laser ablation of hard tissue show the feasibility of using the excimer laser as an additional instrument in general and accident surgery involving minimal invasive surgery. By combining XeCl-excimer lasers and tapered fused silica fibers we obtained output fluences up to 32 J/cm2 and ablation rates of 3 microns/pulse of hard tissue. This enables us to cut bone and cartilage in a period of time which is suitable for clinical operations. Various experiments were carried out on cadavers in order to optimize the parameters of the excimer laser and fibers: e.g., wavelength, pulse duration, energy, repetition rate, fiber core diameter. The surfaces of the cut tissue are comparable to cuts with conventional instruments. No carbonisation was observed. The temperature increase is below 40 degrees C in the tissue surrounding the laser spot. The healing rate of an excimer laser cut is not slower than mechanical treatments; the quality is comparable. PMID:1661360

  7. The elaboration of excimer laser dosimetry for bone and meniscus cutting and drilling using optical fibers

    OpenAIRE

    Jahn, Renate; Dressel, Martin; Neu, Walter; Jungbluth, Karl-Heinz

    1991-01-01

    In order to optimize bone and cartilage ablation various excimer laser systems at 308 nm wavelength (pulse width 28 ns, 60 ns, 300 ns) and tapered fibers (core diameter 400 μm, 600 μm, 1000 μm) were combined. By variing the major parameters such as fluence, pulselength, repetition rate, fiber diameter, medium, manner of application (drilling, cutting) we analysed the interaction of the excimer laser beam with different organic material (meniscus, bone tissue). More than 300 cut...

  8. Psychological aspects of excimer laser surgery for myopia: reasons for seeking treatment and patient satisfaction.

    OpenAIRE

    McGhee, C N; D. Orr; Kidd, B.; C. Stark; Bryce, I G; Anastas, C N

    1996-01-01

    AIMS: To determine the reasons patients seek excimer laser treatment for myopia and to measure levels of patient satisfaction with each phase of this relatively new treatment. METHODS: A unique 38 item visual analogue questionnaire was developed and applied to 100 consecutive patients (n = 100) who had undergone excimer laser photorefractive keratectomy for myopia or myopic astigmatism at a single centre. All subjects underwent extensive ophthalmic assessment and patient education before trea...

  9. Advanced excimer laser technologies enable green semiconductor manufacturing

    Science.gov (United States)

    Fukuda, Hitomi; Yoo, Youngsun; Minegishi, Yuji; Hisanaga, Naoto; Enami, Tatsuo

    2014-03-01

    "Green" has fast become an important and pervasive topic throughout many industries worldwide. Many companies, especially in the manufacturing industries, have taken steps to integrate green initiatives into their high-level corporate strategies. Governments have also been active in implementing various initiatives designed to increase corporate responsibility and accountability towards environmental issues. In the semiconductor manufacturing industry, there are growing concerns over future environmental impact as enormous fabs expand and new generation of equipments become larger and more powerful. To address these concerns, Gigaphoton has implemented various green initiatives for many years under the EcoPhoton™ program. The objective of this program is to drive innovations in technology and services that enable manufacturers to significantly reduce both the financial and environmental "green cost" of laser operations in high-volume manufacturing environment (HVM) - primarily focusing on electricity, gas and heat management costs. One example of such innovation is Gigaphoton's Injection-Lock system, which reduces electricity and gas utilization costs of the laser by up to 50%. Furthermore, to support the industry's transition from 300mm to the next generation 450mm wafers, technologies are being developed to create lasers that offer double the output power from 60W to 120W, but reducing electricity and gas consumption by another 50%. This means that the efficiency of lasers can be improve by up to 4 times in 450mm wafer production environments. Other future innovations include the introduction of totally Heliumfree Excimer lasers that utilize Nitrogen gas as its replacement for optical module purging. This paper discusses these and other innovations by Gigaphoton to enable green manufacturing.

  10. Microencapsulation of silicon cavities using a pulsed excimer laser

    International Nuclear Information System (INIS)

    This work presents a novel low thermal-budget technique for sealing micromachined cavities in silicon. Cavities are sealed without deposition, similar to the silicon surface-migration sealing process. In contrast to the 1100 °C furnace anneal required for the migration process, the proposed technique uses short excimer laser pulses (24 ns), focused onto an area of 23 mm2, to locally heat the top few microns of the substrate, while the bulk substrate remains near ambient temperature. The treatment can be applied to selected regions of the substrate, without the need for special surface treatments or a controlled environment. This work investigates the effect of varying the laser pulse energy from 400 mJ cm−2 to 800 mJ cm−2, the pulse rate from 1 Hz to 50 Hz and the pulse count from 200 to 3000 pulses on sealing microfabricated cavities in silicon. An analytical model for the effect of holes on the surface temperature distribution is derived, which shows that much higher temperatures can be achieved by increasing the hole density. A mechanism for sealing the cavities is proposed, which indicates how complete sealing is feasible. (paper)

  11. Microencapsulation of silicon cavities using a pulsed excimer laser

    KAUST Repository

    Sedky, Sherif M.

    2012-06-07

    This work presents a novel low thermal-budget technique for sealing micromachined cavities in silicon. Cavities are sealed without deposition, similar to the silicon surface-migration sealing process. In contrast to the 1100°C furnace anneal required for the migration process, the proposed technique uses short excimer laser pulses (24ns), focused onto an area of 23mm 2, to locally heat the top few microns of the substrate, while the bulk substrate remains near ambient temperature. The treatment can be applied to selected regions of the substrate, without the need for special surface treatments or a controlled environment. This work investigates the effect of varying the laser pulse energy from 400 mJ cm 2to 800 mJ cm 2, the pulse rate from 1Hz to 50Hz and the pulse count from 200 to 3000 pulses on sealing microfabricated cavities in silicon. An analytical model for the effect of holes on the surface temperature distribution is derived, which shows that much higher temperatures can be achieved by increasing the hole density. A mechanism for sealing the cavities is proposed, which indicates how complete sealing is feasible. © 2012 IOP Publishing Ltd.

  12. Patterning of PLZT and PSZT thin films by excimer laser

    International Nuclear Information System (INIS)

    The patterning of lanthanum-doped lead zirconate titanate (PLZT) and strontium-doped lead zirconate titanate (PSZT) thin films has been examined using a 5-ns pulsed excimer laser. Both types of film were deposited by rf magnetron sputtering with in situ heating and a controlled cooling rate in order to obtain the perovskite-structured films. The depth of laser ablation in both PSZT and PLZT films showed a logarithmic dependence on fluence. The ablation rate of PLZT films was slightly higher than that of PSZT films over the range of fluence (10-150 J/cm2) and increased linearly with number of pulses. The threshold fluence required to initiate ablation was ∝1.25 J/cm2 for PLZT and ∝1.87 J/cm2 for PSZT films. Individual squares were patterned with areas ranging from 10 x 10 μm2 up to 30 x 30 μm2 using single and multiple pulses. The morphology of the etched surfaces comprised globules which had diameters of 200-250 nm in PLZT and 1400 nm in PSZT films. The diameter of the globules has been shown to increase with fluence until reaching an approximately constant size at ≤20 J/cm2 in both types of film. The composition of the films following ablation has been compared using X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy. (orig.)

  13. Patterning of PLZT and PSZT thin films by excimer laser

    Energy Technology Data Exchange (ETDEWEB)

    Leech, P.W. [CSIRO Materials Science and Engineering, Clayton South, MDC Victoria (Australia); Holland, A.S.; Sriram, S.; Bhaskaran, M. [RMIT University, Microelectronics and Materials Technology Centre, School of Electrical and Computer Engineering, GPO Box 2476V, Melbourne, Victoria (Australia)

    2008-06-15

    The patterning of lanthanum-doped lead zirconate titanate (PLZT) and strontium-doped lead zirconate titanate (PSZT) thin films has been examined using a 5-ns pulsed excimer laser. Both types of film were deposited by rf magnetron sputtering with in situ heating and a controlled cooling rate in order to obtain the perovskite-structured films. The depth of laser ablation in both PSZT and PLZT films showed a logarithmic dependence on fluence. The ablation rate of PLZT films was slightly higher than that of PSZT films over the range of fluence (10-150 J/cm{sup 2}) and increased linearly with number of pulses. The threshold fluence required to initiate ablation was {proportional_to}1.25 J/cm{sup 2} for PLZT and {proportional_to}1.87 J/cm{sup 2} for PSZT films. Individual squares were patterned with areas ranging from 10 x 10 {mu}m{sup 2} up to 30 x 30 {mu}m{sup 2} using single and multiple pulses. The morphology of the etched surfaces comprised globules which had diameters of 200-250 nm in PLZT and 1400 nm in PSZT films. The diameter of the globules has been shown to increase with fluence until reaching an approximately constant size at {<=}20 J/cm{sup 2} in both types of film. The composition of the films following ablation has been compared using X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy. (orig.)

  14. Average power scaling of UV excimer lasers drives flat panel display and lidar applications

    Science.gov (United States)

    Herbst, Ludolf; Delmdahl, Ralph F.; Paetzel, Rainer

    2012-03-01

    Average power scaling of 308nm excimer lasers has followed an evolutionary path over the last two decades driven by diverse industrial UV laser microprocessing markets. Recently, a new dual-oscillator and beam management concept for high-average power upscaling of excimer lasers has been realized, for the first time enabling as much as 1.2kW of stabilized UV-laser average output power at a UV wavelength of 308nm. The new dual-oscillator concept enables low temperature polysilicon (LTPS) fabrication to be extended to generation six glass substrates. This is essential in terms of a more economic high-volume manufacturing of flat panel displays for the soaring smartphone and tablet PC markets. Similarly, the cost-effective production of flexible displays is driven by 308nm excimer laser power scaling. Flexible displays have enormous commercial potential and can largely use the same production equipment as is used for rigid display manufacturing. Moreover, higher average output power of 308nm excimer lasers aids reducing measurement time and improving the signal-to-noise ratio in the worldwide network of high altitude Raman lidar stations. The availability of kW-class 308nm excimer lasers has the potential to take LIDAR backscattering signal strength and achievable altitude to new levels.

  15. FEM for modelling 193 nm excimer laser treatment of SiO{sub 2}/Si/Si{sub (1-x)}Ge{sub x} heterostructures on SOI substrates

    Energy Technology Data Exchange (ETDEWEB)

    Conde, J.C.; Chiussi, S.; Gontad, F.; Gonzalez, P. [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, 36310 Vigo (Spain); Martin, E. [Dpto. de Mecanica, Maquinas, Motores Termicos y Fluidos, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, 36310 Vigo (Spain)

    2011-03-15

    Research on epitaxial crystalline silicon (c-Si) and silicon-germanium (Si{sub 1-x}Ge{sub x}) alloys growth and annealing for microelectronic purposes, such as Micro- or Nano-Electro-Mechanical Systems (MEMS or NEMS) and Silicon-On-Nothing (SON) devices is continuously in progress. Laser assisted annealing techniques using commercial ArF Excimer Laser sources are based on ultra-rapid heating and cooling cycles induced by the 193 nm pulses of 20 ns, which are absorbed in the near surface region of the heterostructures. During and after the absorption of these laser pulses, complex physical processes appear that strongly depend on sample structure and applied laser pulse energy densities. The control of the experimental parameters is therefore a key task for obtaining high quality alloys. The Finite ElementsMethod (FEM) is a powerful tool for the optimization of such treatments, because it provides the spatial and temporal temperature fields that are produced by the laser pulses. In this work, we have used a FEM commercial software, to predict the temperatures gradients induced by ArF excimer laser over a wide energy densities range, 0.1<{phi}<0.4 J/cm{sup 2}, on different SiO{sub 2}/Si/Si{sub (1-x)}Ge{sub (x)} thin films deposited on SOI substrate. These numerical results allow us to predict the threshold energies needed to reach the melting point (MP) of the Si and SiGe alloy without oxidation of the thin films system. Therefore, it is possible to optimize the conditions to achieve high quality epitaxy films. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  16. Development of high coherence high power 193nm laser

    Science.gov (United States)

    Tanaka, Satoshi; Arakawa, Masaki; Fuchimukai, Atsushi; Sasaki, Yoichi; Onose, Takashi; Kamba, Yasuhiro; Igarashi, Hironori; Qu, Chen; Tamiya, Mitsuru; Oizumi, Hiroaki; Ito, Shinji; Kakizaki, Koji; Xuan, Hongwen; Zhao, Zhigang; Kobayashi, Yohei; Mizoguchi, Hakaru

    2016-03-01

    We have been developing a hybrid 193 nm ArF laser system that consists of a solid state seeding laser and an ArF excimer laser amplifier for power-boosting. The solid state laser consists of an Yb-fiber-solid hybrid laser system and an Er-fiber laser system as fundamentals, and one LBO and three CLBO crystals for frequency conversion. In an ArF power amplifier, the seed laser passes through the ArF gain media three times, and an average power of 110 W is obtained. As a demonstration of the potential applications of the laser, an interference exposure test is performed.

  17. Excimer laser ablation of polycarbonate-based plastic substrates

    International Nuclear Information System (INIS)

    Ablation of polycarbonate-based plastics under excimer laser irradiation has been studied, with emphasis on the influence of specific inorganic additives in the polymer to the ablation process. Such additives consisted of 0.2 μm sized, (spherical) TiO2 grains, in either 5% or 10% mass concentration. Irradiation products are analyzed, with respect to roughness and ablation, by scanning electron microscopy, energy dispersive X-ray spectroscopy and stylus-profilometry. In the surface region (0-5 μm) of the plastic substrate (i.e. where additives are nearly absent), single pulse irradiation at fluences below 1 J/cm2 yields no ablation and induces the formation of a spongeous polycarbonate medium. Upon repeated irradiation, ablation of this medium proceeds and gives access to the additive-containing material. Evidences are then obtained for subsequent ablation and for a particular structuring of the TiO2-containing material surface in the form of roll-forming cells. The cell formation is indicative of irradiation-monitored melting of the polymer and phase separation between additive and polymer

  18. KrF excimer laser precision machining of hard and brittle ceramic biomaterials.

    Science.gov (United States)

    Huang, Yao-Xiong; Lu, Jian-Yi; Huang, Jin-Xia

    2014-06-01

    KrF excimer laser precision machining of porous hard-brittle ceramic biomaterials was studied to find a suitable way of machining the materials into various desired shapes and sizes without distorting their intrinsic structure and porosity. Calcium phosphate glass ceramics (CPGs) and hydroxyapatite (HA) were chosen for the study. It was found that KrF excimer laser can cut both CPGs and HA with high efficiency and precision. The ablation rates of CPGs and HA are respectively 0.081 µm/(pulse J cm(-2)) and 0.048 µm/(pulse  J cm(-2)), while their threshold fluences are individually 0.72 and 1.5 J cm(-2). The cutting quality (smoothness of the cut surface) is a function of laser repetition rate and cutting speed. The higher the repetition rate and lower the cutting speed, the better the cutting quality. A comparison between the cross sections of CPGs and HA cut using the excimer laser and using a conventional diamond cutting blade indicates that those cut by the excimer laser could retain their intrinsic porosity and geometry without distortion. In contrast, those cut by conventional machining had distorted geometry and most of their surface porosities were lost. Therefore, when cutting hard-brittle ceramic biomaterials to prepare scaffold and implant or when sectioning them for porosity evaluation, it is better to choose KrF excimer laser machining. PMID:24784833

  19. KrF excimer laser precision machining of hard and brittle ceramic biomaterials

    International Nuclear Information System (INIS)

    KrF excimer laser precision machining of porous hard–brittle ceramic biomaterials was studied to find a suitable way of machining the materials into various desired shapes and sizes without distorting their intrinsic structure and porosity. Calcium phosphate glass ceramics (CPGs) and hydroxyapatite (HA) were chosen for the study. It was found that KrF excimer laser can cut both CPGs and HA with high efficiency and precision. The ablation rates of CPGs and HA are respectively 0.081 µm/(pulse ⋅ J cm−2) and 0.048 µm/(pulse ⋅ J cm−2), while their threshold fluences are individually 0.72 and 1.5 J cm−2. The cutting quality (smoothness of the cut surface) is a function of laser repetition rate and cutting speed. The higher the repetition rate and lower the cutting speed, the better the cutting quality. A comparison between the cross sections of CPGs and HA cut using the excimer laser and using a conventional diamond cutting blade indicates that those cut by the excimer laser could retain their intrinsic porosity and geometry without distortion. In contrast, those cut by conventional machining had distorted geometry and most of their surface porosities were lost. Therefore, when cutting hard–brittle ceramic biomaterials to prepare scaffold and implant or when sectioning them for porosity evaluation, it is better to choose KrF excimer laser machining. (paper)

  20. Selective area in situ conversion of Si (0 0 1) hydrophobic to hydrophilic surface by excimer laser irradiation in hydrogen peroxide

    International Nuclear Information System (INIS)

    We report on a method of rapid conversion of a hydrophobic to hydrophilic state of an Si (0 0 1) surface irradiated with a relatively low number of pulses of an excimer laser. Hydrophilic Si (0 0 1), characterized by the surface contact angle (CA) of near 15°, is fabricated following irradiation with either KrF or ArF excimer lasers of hydrophobic samples (CA ∼ 75°) immersed in a 0.01% H2O2/H2O solution. The chemical and structural analysis carried with x-ray photoelectron spectroscopy and atomic force microscopy measurements confirmed the formation of OH-terminated Si (0 0 1) surface with no detectable change in the surface morphology of the laser-irradiated material. To investigate the efficiency of this laser-induced hydrophilization process, we demonstrate a selective area immobilization of biotin-conjugated fluorescein-stained nanospheres outside of the laser-irradiated area. The results demonstrate the potential of the method for the fabrication of biosensing architectures and advancements of the Si-based microfluidic device technology. (paper)

  1. High efficiency metal marking with CO2 laser and glass marking with excimer laser

    DEFF Research Database (Denmark)

    Bastue, Jens; Olsen, Flemmming Ove

    1997-01-01

    with a thoroughly tested ray-tracing model is presented and compared with experimental results. Special emphasis is put on two different applications namely marking in metal with TEA-CO2 laser and marking in glass with excimer laser. The results are evaluated on the basis of the achievable energy enhancement......Today, mask based laser materials processing and especially marking is widely used. However, the energy efficiency in such processes is very low [1].This paper gives a review of the results, that may be obtained using the energy enhancing technique [1]. Results of simulations performed...

  2. KrF excimer laser micromachining of MEMS materials: characterization and applications

    International Nuclear Information System (INIS)

    Conventional photolithography-based microfabrication techniques are widely used to create microscale structures and devices nowadays. However, these techniques are limited to two-dimensional fabrication and also to particular materials. Excimer laser micromachining enables us to overcome those limitations and facilitates three-dimensional (3D) microfabrication. This paper presents a comprehensive characterization study for excimer laser micromachining of micro-electro-mechanical system (MEMS) materials. By using a 248 nm KrF excimer laser and four representative MEMS materials (Si, soda-lime glass, SU-8 photoresist and poly-dimethysiloxane (PDMS)), the relations between laser ablation parameters (fluence, frequency and number of laser pulses) and etch performance such as the etch rates in the vertical and lateral directions, aspect ratio, and surface quality were obtained. The etch rate increased almost linearly for all four materials as the fluence increased but no significant variation in etch rate was observed as the frequency of laser pulses was changed. The etch rate was also inversely proportional to the number of laser pulses. Physical deformation in the laser-machined sites on PDMS and SU-8 was investigated using SEM imaging. In order to demonstrate the 3D microfabrication capability of an excimer laser and the utility of this characterization study, two novel implantable biomedical microscale devices made of SU-8 and PDMS were successfully fabricated using the optimized laser ablation parameters obtained in this study

  3. Excimer laser-induced formation of metallic microstructures by electroless copper plating

    Science.gov (United States)

    Yang, H.; Pan, C.-T.

    2002-03-01

    Micro-patterns created by the excimer laser and activated by reactants for electroless copper plating are described in this paper. The generated micro-patterns are transformed into copper patterns on the substrate and copper microstructures are formed. This method simplifies the manufacturing process of making circuits on boards compared with the conventional lithography process of forming copper patterns on the substrate. Micro-patterns generated by the excimer laser cause changes of surface electric properties and activation selectively. A chemical reaction through these activated areas may deposit metal, such as copper. The KrF excimer laser not only provides simple and fast machining patterns, but also uses its high-energy density to drill holes and circuits directly. Palladium ions are added as mediators in the electroless plating solution to enable a continuous electroless copper deposition. According to the experiment of excimer laser-assisted electroless copper plating, the procedures of pretreatment and post-cleaning are the key factors that resulted in excellent selective plating. The samples were pretreated by sodium dodecyl sulfate (SDS) and post-cleaned by acetone and diluted nitric acid resulting in distinct micro-patterns. The deposition area is confined to the excimer laser-ablated portion resulting in good selective plating.

  4. Plaque Ablation by Excimer Laser Irradiation Using a Movable Energy-Transmitting Device

    OpenAIRE

    Laufer, Günther; Wollenek, Gregor; Stangl, Günther; Klepetko, Walter; Fasol, Roland; Zilla, Peter; Wolner, Ernst

    1987-01-01

    During the past 2 years, excimer laser energy has been shown to provide a highly suitable type of atherosclerotic plaque ablation, especially in small-diameter vessels such as coronary or crural arteries. Nevertheless, transmission of far-ultraviolet pulsed laser power has remained a major problem in animal studies and clinical trials.

  5. Stability of a 1-kW excimer laser with long optical pulses

    NARCIS (Netherlands)

    Timmermans, J.C.M.; Hofmann, Th.; Goor, van F.A.; Witteman, W.J.

    1997-01-01

    For high repetition operation of excimer-lasers care has to be taken of the changing performance of the electrical circuit, gas dynamic effects and contamination of the gas mixture to avoid deterioration of the laser performance. The parameters that influence the stability of the discharge are discu

  6. Laser damage testing of coated reflectors at excimer laser wavelengths

    International Nuclear Information System (INIS)

    An important parameter in the design of large-scale ultraviolet lasers (such as those envisioned for Inertial Confinement Fusion and Molecular Laser Isotope Separation) is the resistance to optical damage of windows, AR-coatings, and coated reflectors. In addressing the problem of evaluating and optimizing highly reflective dielectric stacks, we have measured the damage thresholds of a variety of 248-nm, 308-nm, and 351-nm reflectors. The coatings were composed of quarterwave stacks of oxide and/or fluoride films deposited on Suprasil 2 substrates. Testing was accomplished at 35 Hz with nominal 10-ns pulses focused to a mean 1/e2 diameter of 0.5 to 0.6 mm. Damage threshold (defined as the highest fluence at which 10/10 sites survived 1000 shots) ranged from 1 to 5 J/cm2, with a strong dependence upon laser wavelength and reflector coating materials

  7. Surface modification of polyethylene terephthalate using excimer and CO2 laser

    International Nuclear Information System (INIS)

    Complete text of publication follows. Attempts have been made to evaluate microstructuring which affects cell behaviour, physical and chemical changes produced by laser irradiation onto the polyethylene terephthalate (PET) surface. The surfaces of PET were irradiated using the CO2 laser and KrF excimer pulsed laser. The changes in chemical and physical properties of the irradiated PET surface were investigated by attenuated total reflectance infrared spectroscopy (ATR-IR) and contact angle measurements. ATR-IR Spectra showed that the crystallinity in the surface region decreased due to the CO2 laser and excimer laser irradiation. Scanning electron microscopy observations showed that the morphology of the laser irradiated PET surface changed due to laser irradiation. The results obtained from the cell behaviour studies revealed that changes of physico-chemical properties of the laser treated PET film have significantly changed in comparison with the unmodified PET

  8. Excimer laser micromachining of oblique microchannels on thin metal films using square laser spot

    Indian Academy of Sciences (India)

    SYED NADEEM AKHTAR; SHASHANK SHARMA; S ANANTHA RAMAKRISHNA; J RAMKUMAR

    2016-06-01

    Excimer laser micromachining of thin metal films with a sacrificial polymer coating is a novel technique that produces features with smooth edges. Using this technique, oblique microchannels are fabricated by workpiece dragging and using a square laser spot, where the axis of traverse of the workpiece is not parallel to the edges of the square laser spot. The microchannels have serrated edges that are particular to the shape of the mask producing the spot. The edge roughness of the channels, machined with a square laser spot of side 100lm, is found to be most affected by the fluence–spot overlap interaction, and the channel width by spot-overlap and the angle of tilt of the traversed path. Polymer coated metal films underwent close to ideal machining, aided by the clamping action of the polymer layer. Through this technique of machining post polymer coating, the edge roughnesses of the microchannels have been curtailed to less than 10 lm, and channel widths to 150 lm. This technique may be used in fabrication of oblique and circular patterns using excimer laser micromachiningwith rectangular and square laser spots

  9. Mesoscale Laser Processing using Excimer and Short-Pulse Ti: Sapphire Lasers

    Energy Technology Data Exchange (ETDEWEB)

    Shirk, M D; Rubenchik, A M; Gilmer, G H; Stuart, B C; Armstrong, J P; Oberhelman, S K; Baker, S L; Nikitin, A J; Mariella, R P

    2003-07-28

    Targets to study high-energy density physics and inertial confinement fusion processes have very specific and precise tolerances that are pushing the state-of-the-art in mesoscale microsculpting technology. A significant effort is required in order to advance the capabilities to make these targets with very challenging geometries. Ultrashort pulsed (USP) Ti:Sapphire lasers and excimer lasers are proving to be very effective tools in the fabrication of the very small pieces that make up these targets. A brief description of the dimensional and structural requirements of these pieces will be presented, along with theoretical and experimental results that demonstrate to what extent these lasers are achieving the desired results, which include sub-{mu}m precision and RMS surface values well below 100 nm. This work indicates that excimer lasers are best at sculpting the polymer pieces and that the USP lasers work quite well on metal and aerogel surfaces, especially for those geometries that cannot be produced using diamond machining and where material removal amounts are too great to do with focused ion beam milling in a cost effective manner. In addition, the USP laser may be used as part of the procedure to fill target capsules with fusion fuel, a mixture of deuterium and tritium, without causing large perturbations on the surface of the target by keeping holes drilled through 125 {micro}m of beryllium below 5 {micro}m in diameter.

  10. Mutagenic potential of a 193-nm excimer laser on fibroblasts in tissue culture

    International Nuclear Information System (INIS)

    In response to concerns regarding possible DNA damage by far ultraviolet radiation during excimer laser corneal surgery, the mutagenic potential of an argon fluoride excimer laser (193 nm) on BALB/3T3 mouse fibroblasts grown in tissue culture was investigated. The cumulative incidence of anaplastic transformation after subablative radiant exposures from 3.5 mJ/cm2/pulse to 13.4 mJ/cm2/pulse was 3.6% of all cell cultures. The incidence of anaplastic transformation in nonirradiated controls was 4.2%. Transformation after exposure to x-ray radiation (60.9 rad) was 98.8%. The difference between the incidence of transformation of nonirradiated controls or excimer-treated cultures compared with x-ray radiation-treated cells was significant P less than 0.0001 (chi square test). In this standard cell line, 193-nm laser energy does not appear to have substantial mutagenic potential

  11. Discharge studies with a high-efficiency XeCl excimer laser

    OpenAIRE

    Trentelman, M.; Ekelmans, G.B.; Goor, van, H.; Witteman, W.J.

    1990-01-01

    Results on a high efficiency excimer laser operating according to the prepulse-mainpulsetechnique are reported. The laser volume of about 90 cm is X-ray preionized. The mainpulse obtained from a PFN 2 swiched onto the discharge by means of a racetrack saturable inductor (magnetic switching) connected to the laser head with low inductance. Laser output energy has been measured as a function of gas mixture and delay between X-ray and prepulse.

  12. Prevention and treatment of transient dry eye following excimer laser surgery

    Directory of Open Access Journals (Sweden)

    V. V. Pogorelovа

    2015-01-01

    Full Text Available To compare dry eye symptoms after LASIK with mechanical keratome-created flaps and femtosecond laser keratome-created flaps as well as to analyze the efficacy of Systane® Ultra Monodose used to prevent and to treat transient dry eye after excimer laser surgery. Methods: 98 patients (194 eyes with myopia and compound myopic astigmatism who underwent excimer laser surgery were included in the study. In group 1 patients with pre-op dry eye, femtosecond laser-assisted LASIK was performed, Systane® Ultra Monodose was prescribed postoperatively. In group 2 patients with pre-op dry eye, LASIK was performed using mechanical microkeratome, Systane® Ultra Monodose was prescribed postoperatively. In group 3 patients without pre-op dry eye, LASIK was performed using mechanical microkeratome, standard anti-inflammatory therapy without any lubricant eye drops was prescribed. Patients were followed up for 60 days. Results: It was demonstrated that excimer laser surgery provokes transient dry eye in all patients, therefore, artificial tears are required for 2 months and more after the surgery. Post-operative lubricant eye drops use improves tear film stability, tear production, tear osmolarity, and objective signs of dry eye. Femtosecond laser decreases clinical and functional symptoms of transient dry eye as compared with mechanical microkeratome and provides more rapid visual recovery. Conclusion: Systane® Ultra Monodose has both high efficiency and good tolerability. It can be recommended for the prevention and treatment of dry eye following excimer laser surgery.

  13. Chemical evolution of InP/InGaAs/InGaAsP microstructures irradiated in air and deionized water with ArF and KrF lasers

    International Nuclear Information System (INIS)

    Irradiation of quantum semiconductor microstructures with ultraviolet pulsed lasers could induce surface defects and modify chemical composition of the microstructure capping material that during high-temperature annealing leads to selected area bandgap engineering through the process known as quantum well intermixing (QWI). In this work, we investigate the role of both ArF and KrF excimer lasers in the QWI process of InP/InGaAs/InGaAsP microstructures irradiated in air and deionized (DI) water. X-ray photoelectron spectroscopy and secondary ion mass spectroscopy analysis was employed to study the chemical composition of the irradiated surface and investigate the chemical evolution of ArF and KrF laser irradiated microstructures. The results indicate that InPxOy oxides are the dominating surface products of the ArF and KrF lasers interaction with InP. Consistent with this observation is a relatively greater bandgap blue shift of ∼130 nm found in the microstructures irradiated in air, in comparison to a maximum of 60 nm blue shift observed in the microstructures irradiated in a DI water environment.

  14. [PKP for Keratoconus - From Hand/Motor Trephine to Excimer Laser and Back to Femtosecond Laser].

    Science.gov (United States)

    Seitz, B; Szentmáry, N; Langenbucher, A; Hager, T; Viestenz, A; Janunts, E; El-Husseiny, M

    2016-06-01

    For patients with keratoconus, rigid gas-permeable contact lenses are the first line correction method and allow good visual acuity for quite some time. In severe stages of the disease with major cone-shaped protrusion of the cornea, even specially designed keratoconus contact lenses are no longer tolerated. If there are contraindications for intrastromal ring segments, corneal transplantation typically has a very good prognosis. In patients with advanced keratoconus - especially after corneal hydrops due to rupture of Descemet's membrane - penetrating keratoplasty (PKP) is still the first line surgical method. Non-contact excimer laser trephination seems to be especially beneficial for eyes with iatrogenic keratectasia after LASIK and for patients with repeat grafts due to "keratoconus recurrences" due to small grafts with thin host cornea. For donor trephination from the epithelial side, an artificial chamber is used. Wound closure is achieved with a double running cross-stitch suture according to Hoffmann. Graft size is adapted individually, depending on corneal size ("as large as possible - as small as necessary"). Limbal centration is preferred intraoperatively, due to optical displacement of the pupil. During the last 10 years, femtosecond laser trephination has been introduced from the USA as a potentially advantageous approach. Prospective clinical studies have shown that the technique of non-contact excimer laser PKP improves donor and recipient centration, reduces "vertical tilt" and "horizontal torsion" of the graft in the recipient bed, and thus results in significantly less "all-sutures-out" keratometric astigmatism (2.8 vs. 5.7 D), more regular topography (surface regularity index [SRI] 0.80 vs. 1.0) and better visual acuity (0.80 vs. 0.60), in comparison to the motor trephine. The stage of the disease does not influence functional outcome after excimer laser PKP. However, the refractive outcome of femtosecond laser keratoplasty resembles that with

  15. A comparison of the characteristics of excimer and femtosecond laser ablation of acrylonitrile butadiene styrene (ABS)

    Science.gov (United States)

    See, Tian Long; Liu, Zhu; Li, Lin; Zhong, Xiang Li

    2016-02-01

    This paper presents an investigation on the ablation characteristics of excimer laser (λ = 248 nm, τ = 15 ns) and femtosecond laser (λ = 800 nm, τ = 100 fs) on ABS polymer sheets. The laser-material interaction parameters (ablation threshold, optical penetration depth and incubation factor) and the changes in material chemical properties were evaluated and compared between the two lasers. The work shows that the ablation threshold and effective optical penetration depth values are dependent on the wavelength of laser beam (photon energy) and the pulse width. The ablation threshold value is lower for the excimer laser ablation of ABS (Fth = 0.087 J/cm2) than that for the femtosecond laser ablation of ABS (Fth = 1.576 J/cm2), demonstrating a more dominating role of laser wavelength than the pulse width in influencing the ablation threshold. The ablation depth versus the logarithmic scale of laser fluence shows two linear regions for the fs laser ablation, not previously known for polymers. The effective optical penetration depth value is lower for excimer laser ablation (α-1 = 223 nm) than that for femtosecond laser ablation (α-1 = 2917 nm). The ablation threshold decreases with increasing number of pulses (NOP) due to the chain scission process that shortens the polymeric chains, resulting in a weaker polymeric configuration and the dependency is governed by the incubation factor. Excimer laser treatment of ABS eliminates the Cdbnd C bond completely through the chain scission process whereas Cdbnd C bond is partially eliminated through the femtosecond laser treatment due to the difference in photon energy of the two laser beams. A reduction in the Cdbnd C bond through the chain scission process creates free radical carbons which then form crosslinks with each other or react with oxygen, nitrogen and water in air producing oxygen-rich (Csbnd O and Cdbnd O bond) and nitrogen-rich (Csbnd N) functional groups.

  16. Excimer laser surface processing for tribological applications in metals and ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Jervis, T.R.; Hivonen, Juha-Pekka; Nastasi, M.

    1991-01-01

    The use of pulsed excimer lasers, operating at UV wavelengths, for surface modification has many potential applications in the tribology of metals and ceramics. Alterations of surface chemistry and microstructure are possible on standard engineering materials. We have demonstrated improved tribological performance in stainless steel by the formation of a unique oxide and by Ti mixing and in SiC by Ti mixing. Specifically, we have observed reduced friction in dry sliding conditions and a change in the wear process resulting in greatly reduced surface damage. We have also demonstrated the effectiveness of excimer laser mixing in other systems with potential tribological applications. 22 refs., 7 figs.

  17. Azide-styrene resin negative deep UV resist for KrF excimer laser lithography

    International Nuclear Information System (INIS)

    The authors report a photosensitive composition, consisting of an aromatic azide compound (4,4'diazidodiphenyl methane) and a styrene resin (poly(styrene-co-maleic acid half-isoprapylate)), developed and evaluated as a negative deep ultra-violet (UV) resist for high-resolution KrF excimer laser lithography. Solubility of this resist in an aqueous developer decreases upon exposure to KrF excimer laser irradiation. The alkaline developer removes the unexposed areas of this resist. No swelling-induced pattern deformation occurs and high aspect ratio sub-half-micron patterns in 1.0 μm film thickness are obtained with high sensitivity

  18. Numerical analysis of temperature profile and thermal-stress during excimer laser induced heteroepitaxial growth of patterned amorphous silicon and germanium bi-layers deposited on Si(100)

    Energy Technology Data Exchange (ETDEWEB)

    Conde, J.C., E-mail: jconde@uvigo.e [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain); Martin, E. [Dpto. de Mecanica, Maquinas y Motores Termicos y Fluidos, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain); Gontad, F.; Chiussi, S. [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain); Fornarini, L. [Enea-Frascati, Via Enrico Fermi 45, I-00044 Frascati (Roma) (Italy); Leon, B. [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain)

    2010-02-26

    A Finite Element Method (FEM) study of the coupled thermal-stress during the heteroepitaxial growth induced by excimer laser radiation of patterned amorphous hydrogenated silicon (a-Si:H) and germanium (a-Ge:H) bi-layers deposited on a Si(100) wafer is presented. The ArF (193 nm) excimer laser provides high energy densities during very short laser pulse (20 ns) provoking, at the same time, melting and solidification phenomena in the range of several tenths of nanoseconds. These phenomena play an important role during the growth of heteroepitaxial SiGe structures characterized by high Ge concentration buried under a Si rich surface. In addition, the thermal-stresses that appear before the melting and after the solidification processes can also affect to the epitaxial growth of high quality SiGe alloys in these patterned structures and, in consequence, it is necessary to predict their effects. The aim of this work is to estimate the energy threshold and the corresponding thermal-stresses in the interfaces and the borders of these patterned structures.

  19. Feasibility of depth profiling of Zn-based coatings by laser ablation inductively coupled plasma optical emission and mass spectrometry using infrared Nd:YAG and ArF* lasers

    International Nuclear Information System (INIS)

    The feasibility of depth profiling of zinc-coated iron sheets by laser ablation (LA) was studied using an Nd:YAG laser (1064 nm) with inductively coupled plasma optical emission spectrometry (ICP-OES), and an excimer ArF* laser (193 nm) with a beam homogenizer. The latter was coupled to an ICP with mass spectrometry (ICP-MS). Fixed-spot ablation was applied. Both LA systems were capable of providing depth profiles that approach the profiles obtained by glow discharge optical emission spectroscopy (GD-OES) and electron probe X-ray microanalysis (EPXMA). For Nd:YAG laser an artefact consisting of zinc depth profile signal tailing appeared, enlarging thus erroneously diffusional coating-substrate interface profile. However, the ArF* system partially reduced but not suppressed that phenomenon. For both LA systems the Fe signal from the substrate increased with depth as expected and reached a plateau. The depth resolution (depth range corresponding to 84%-16% change in the full signal) achieved was several micrometers. Ablation rate was found to depend on ablation spot area at constant irradiance. Consequently, ablated volume per shot dependence on pulse energy exhibits deviation from linear course

  20. Feasibility of depth profiling of Zn-based coatings by laser ablation inductively coupled plasma optical emission and mass spectrometry using infrared Nd:YAG and ArF* lasers

    Energy Technology Data Exchange (ETDEWEB)

    Hrdlicka, Ales [Laboratory of Atomic Spectrochemistry, Faculty of Science, Masaryk University in Brno, Kotlarska 2, CZ 611 37 Brno (Czech Republic)]. E-mail: ahrdlicka@chemi.muni.cz; Otruba, Vitezslav [Laboratory of Atomic Spectrochemistry, Faculty of Science, Masaryk University in Brno, Kotlarska 2, CZ 611 37 Brno (Czech Republic); Novotny, Karel [Laboratory of Atomic Spectrochemistry, Faculty of Science, Masaryk University in Brno, Kotlarska 2, CZ 611 37 Brno (Czech Republic); Guenther, Detlef [Laboratory of Inorganic Chemistry, ETH Zurich, Hoenggerberg HCI G113, Wolfgang-Pauli-Strasse 10, CH-8083 Zurich (Switzerland); Kanicky, Viktor [Laboratory of Atomic Spectrochemistry, Faculty of Science, Masaryk University in Brno, Kotlarska 2, CZ 611 37 Brno (Czech Republic)]. E-mail: viktork@chemi.muni.cz

    2005-03-31

    The feasibility of depth profiling of zinc-coated iron sheets by laser ablation (LA) was studied using an Nd:YAG laser (1064 nm) with inductively coupled plasma optical emission spectrometry (ICP-OES), and an excimer ArF* laser (193 nm) with a beam homogenizer. The latter was coupled to an ICP with mass spectrometry (ICP-MS). Fixed-spot ablation was applied. Both LA systems were capable of providing depth profiles that approach the profiles obtained by glow discharge optical emission spectroscopy (GD-OES) and electron probe X-ray microanalysis (EPXMA). For Nd:YAG laser an artefact consisting of zinc depth profile signal tailing appeared, enlarging thus erroneously diffusional coating-substrate interface profile. However, the ArF* system partially reduced but not suppressed that phenomenon. For both LA systems the Fe signal from the substrate increased with depth as expected and reached a plateau. The depth resolution (depth range corresponding to 84%-16% change in the full signal) achieved was several micrometers. Ablation rate was found to depend on ablation spot area at constant irradiance. Consequently, ablated volume per shot dependence on pulse energy exhibits deviation from linear course.

  1. High Efficiency Mask Based Laser Materials Processing with TEA-CO2 - and Excimer Laser

    DEFF Research Database (Denmark)

    Bastue, Jens; Olsen, Flemmming Ove

    1997-01-01

    In general, mask based laser materials processing techniques suffer from a very low energy efficiency. We have developed a simple device called an energy enhancer, which is capable of increasing the energy efficiency of typical mask based laser materials processing systems. A short review of the...... line marking with TEA-CO2 laser of high speed canning lines. The second one is manufactured for marking or microdrilling with excimer laser....... most widely used applications of these systems is given and the potential advantages of the energy enhancer are discussed.The basic principle behind the energy enhancing technique is explained and two new energy enhancers are presented and evaluated. The first one is designed especially for single text...

  2. Photodynamic Therapy for Superficial Esophageal Cancer Using an Excimer Dye Laser

    OpenAIRE

    Seishiro Mimura; Toru Otani; Shigeru Okuda

    1994-01-01

    In order to improve the therapeutic effectiveness of photodynamic therapy with Photofrin II and laser light for superficial esophageal cancer, we employed an excimer dye laser instead of an argon dye laser. Eight superficial esophageal cancer lesions (7 cases) were treated. Of these 8 lesions, 6 were cured by initial treatment, while one lesion required another treatment. The final rate of cure was 88% (7/8).

  3. On the operation of a long-pulse KrCl excimer laser

    OpenAIRE

    Casper, Lars Christian

    2007-01-01

    High-power lasers pumped by a gas discharge are extensively used in industrial applications. Of particular importance are lasers pumped by an electric discharge in excimer gas mixtures because this allows the generation of powerful ultraviolet radiation (UV), with wavelengths below 350 nm. Due to the short wavelength, these lasers offer the unique possibility to structure materials on the sub-micron scale, when focused or with mask techniques. Also, the absorption of UV radiation is strong in...

  4. Axial and transverse displacement tolerances during excimer laser surgery for myopia

    Science.gov (United States)

    Shimmick, John K.; Munnerlyn, Charles R.; Clapham, Terrance N.; McDonald, Marguerite B.

    1991-06-01

    This paper presents an analysis of the effects of axial and transverse displacement on the optical quality and accuracy of lenses created during excimer laser photoablation. Tolerance levels for axial positioning of the cornea prior to and during surgery are presented. The axial tolerance levels are dependent upon a number of parameters which include the intended dioptric correction and laser system cone angle. A collimation lens is introduced as a means of desensitizing the laser system to axial displacement. Transverse displacement tolerances during laser treatment are shown to depend upon the treatment diameter, dioptric correction and acceptable distortion level in the lens ablated into the anterior corneal stroma. A video and computer analysis of transverse motion during seven randomly selected excimer laser refractive surgeries is presented. Although transverse displacement exceeded the tolerance levels presented, it did not appear to affect the quality of correction in the eight patients analyzed.

  5. Measurement of solid--liquid interface temperature during pulsed excimer laser melting of polycrystalline silicon films

    International Nuclear Information System (INIS)

    A nanosecond time resolution pyrometer has been developed for measuring the transient temperature of thin polycrystalline silicon (p-Si) films irradiated by a pulsed excimer laser. The sample design structure and material optical properties allow direct measurement of the temperature at the solid--liquid phase change interface

  6. Excimer laser crystallization of InGaZnO4 on SiO2 substrate

    NARCIS (Netherlands)

    Chen, T.; Wu, M.-Y.; Ishihara, R.; Nomura, K.; Kamiya, T.; Hosono, H.; Beenakker, C.I.M.

    2011-01-01

    In this paper, we were able to crystallize InGaZnO4 (IGZO) by excimer laser on SiO2 substrate. It was observed that uniform [0001] textured polycrystalline IGZO film has been obtained without any grain boundaries and oxygen vacancies on SiO2 substrate. This process is very promising in fabricating h

  7. A pulsed electron injector using a metal photocathode irradiated by an excimer laser

    International Nuclear Information System (INIS)

    The hot cathode of an electron gun is replaced by a metallic photocathode driven by an excimer laser. The current, current density, and emittance of the 500-kV electron beam produced by the photoelectron source are presented. In addition, the temperature of the photocathode is varied to study the possibility of a hybrid source

  8. Preparation of Nanostructurated Materials by ArF Laser Ablation

    Czech Academy of Sciences Publication Activity Database

    Koštejn, Martin; Fajgar, Radek; Tomovska, R.; Blazevska-Gilev, J.

    -: -, 2014, s. 243. ISBN N. [International Conference on Nanosciences & Nanotechnologie (NN13) /10./. Thessaloniki (GR), 09.07.2014-12.07.2014] Institutional support: RVO:67985858 Keywords : laser ablation * electron diffraction * spectroscopy Subject RIV: CH - Nuclear ; Quantum Chemistry

  9. [Percutaneous coronary Excimer laser angioplasty in patients with coronary heart disease].

    Science.gov (United States)

    Karsch, K R; Haase, K K; Mauser, M; Ickrath, O; Voelker, W; Baumbach, A; Seipel, L

    1990-07-01

    To verify the efficacy and safety of percutaneous coronary excimer laser angioplasty in patients with coronary artery disease a prospective study was conducted in 60 patients. The application of laser light was possible in 55 of the 60 patients. A novel 1.4-mm diameter catheter with 20 quartz fibers of 100-microns diameter, each arranged concentrically around a central lumen suitable for an 0.014-inch flexible guide wire was used. The light source was a commercial excimer laser emitting energy at a wavelength of 308 nm, with a pulse duration of 60 ns. The laser was operated at 20 Hz; mean energy transmission was 30 +/- 5 mJ/mm2. In 23 of the 55 patients treated with excimer laser energy the qualitative angiographic results were sufficient. In 32 patients additional balloon angioplasty was necessary, either because of an insufficient result or due to vessel closure after laser ablation. In 47 of the 55 patients control angiography was performed within the 6-month follow-up period. Rate of restenosis was higher in patients treated with laser ablation and subsequent balloon angioplasty (16 of 28) than in patients treated with laser ablation alone (6 of 19). Results of the 6-month observation period suggest that 1) coronary excimer laser angioplasty in combination with subsequent balloon angioplasty results in a considerable increase of the restenosis rate; 2) the exclusive use of laser ablation also results in a restenosis rate comparable to balloon angioplasty alone; and 3) the impact of this new method using improved application systems and higher energy transmission has to be determined in further studies. PMID:2399764

  10. Fabrication of the Long Bragg Grating by Excimer Laser Micro Machining with High-Precision Positioning XXY Platform

    OpenAIRE

    Jian-Zhong Wu; Jian-Cin Chao; Jui-Yi Hu; Chia-Chin Chiang

    2014-01-01

    With the advancement of technology, the application of fiber Bragg grating is widely used as a Bragg grating sensor. Fiber Bragg grating is fabrication using excimer laser machining with the phase masker. The grating length is decided by the width of laser beam. In this paper, we proposed fabrication of the long Bragg grating by excimer Laser micro machining with a high-precision positioning XXY platform. The high-precision positioning XXY platform plays an important role for long FBG. It nee...

  11. Excimer laser processing of tool steel: Tribological effects of multiple pulse processing and titanium alloying

    Energy Technology Data Exchange (ETDEWEB)

    Jervis, T.R.; Nastasi, M.; Griffin, A.J. Jr.; Zocco, T.G.; Taylor, T.N.; Foltyn, S.R.

    1995-12-01

    Excimer lasers were used to modify the surface of AISI type A-7 tool steel, a high C, high V, high Cr material used in many cutting applications. Multiple pulses of laser radiation at 248 nm were used to alter the composition of the surface alloy. Hardness and modulus were not significantly affected by the treatment, but friction in dry sliding against an alumina pin was reduced. The reduction was small but persistent for multiply melted and resolidified surfaces. These surfaces showed a marked increase in the surface Cr concentration. Greater reductions in friction were obtained from a Ti rich surface layer formed by laser mixing an evaporated Ti layer into the material. The friction coefficient of the Ti alloyed surface deteriorated after approximately 1000 cycles, indicating wear=through of the modified surface. The observed properties will be discussed in terms of the excimer laser modification process and the microstructure and composition of the resulting surfaces.

  12. Development of a low impedance electron-beam system for high power excimer laser excitation

    International Nuclear Information System (INIS)

    Two modules of a low impedance electron-beam machine have been developed to pump a 200 J, 70 ns KrF laser. The laser is designed as the final amplifier of a tera-watt level picosecond excimer laser system. The operating characteristics of this device have been studied. The energy deposited in the 42 litter laser gain region is measured by several different diagnostics to be 3 kJ with good spatial uniformity. The triggered operation of the 500 kV main rail switch, which is essential for system synchronization, has been demonstrated by the UV laser irradiation along the rail gap axis

  13. Vacuum ultraviolet Ar excimer emission initiated by high intensity laser produced electrons

    International Nuclear Information System (INIS)

    We have observed Ar2* emission using a tabletop femtosecond high intensity laser as an excitation source. High intensity laser produced electrons via an optical field induced ionization (OFI) process initiated the Ar2* production kinetics, which made themselves analogous to those produced in an electron beam produced plasma. A fast conductive cooling of the OFI plasma was found to be appropriate to initiate the excimer formation kinetics more efficiently. (author)

  14. Bioactive glass surface for fiber reinforced composite implants via surface etching by Excimer laser.

    Science.gov (United States)

    Kulkova, Julia; Moritz, Niko; Huhtinen, Hannu; Mattila, Riina; Donati, Ivan; Marsich, Eleonora; Paoletti, Sergio; Vallittu, Pekka K

    2016-07-01

    Biostable fiber-reinforced composites (FRC) prepared from bisphenol-A-glycidyldimethacrylate (BisGMA)-based thermosets reinforced with E-glass fibers are promising alternatives to metallic implants due to the excellent fatigue resistance and the mechanical properties matching those of bone. Bioactive glass (BG) granules can be incorporated within the polymer matrix to improve the osteointegration of the FRC implants. However, the creation of a viable surface layer using BG granules is technically challenging. In this study, we investigated the potential of Excimer laser ablation to achieve the selective removal of the matrix to expose the surface of BG granules. A UV-vis spectroscopic study was carried out to investigate the differences in the penetration of light in the thermoset matrix and BG. Thereafter, optimal Excimer laser ablation parameters were established. The formation of a calcium phosphate (CaP) layer on the surface of the laser-ablated specimens was verified in simulated body fluid (SBF). In addition, the proliferation of MG63 cells on the surfaces of the laser-ablated specimens was investigated. For the laser-ablated specimens, the pattern of proliferation of MG63 cells was comparable to that in the positive control group (Ti6Al4V). We concluded that Excimer laser ablation has potential for the creation of a bioactive surface on FRC-implants. PMID:27134152

  15. Remarkable enhancement on elimination reaction of side groups in excimer laser ablation of mixture targets of perylene derivatives with metal powder

    International Nuclear Information System (INIS)

    Films are deposited on substrates at 20 deg.C by excimer laser ablation (ELA) of mixture targets of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) with metal powder, PTCDA/M (M=Co, Ni, Fe, W, Cu and Ag) using XeCl and ArF beams. Large amount of fragments with ''naked'' perylene skeletons can be produced owing to effective elimination of carboxylic dianhydride groups by ELA of PTCDA/Co both with XeCl and ArF beams under optimized ablation conditions. Elimination reaction of side groups of PTCDA is observed for ELA of the targets with metal powder of the iron group, Co, Fe and Ni, especially remarkable for Co and Fe. The film from PTCDA/Ni consists of small particles with the various diameters ranging from 10 to 100 nm as well as that from PTCDA/Co. Morphology like petal of rose can be seen everywhere for the film from PTCDA/Fe

  16. Analysis and fabrication of minifeature lamp lens by excimer laser micromachining.

    Science.gov (United States)

    Hocheng, Hong; Wang, Kuan-Yu

    2007-10-10

    A variety of shapes of lamp lenses at the feature millimeter scale have been extensively used in lamp design. To further improve the light efficiency and to reduce the overall dimension of lamps, the lamp lens at the micrometer scale is fabricated by excimer laser cross scanning on a polycarbonate sheet. To verify the proposed method, the influence of an optical system with various shapes and sizes of lamp lenses on the light efficiency is explored in advance by ASAP optical software. The lens with a miniature feature can produce a smaller divergence angle than that with a large-size lens feature. The experiment is carried out at varying laser operating parameters, mask shape, and dimensions. The simulation shows that the desired lamp lens profile can be effectively produced by excimer laser micromachining. PMID:17932527

  17. Ablation and cone formation mechanism on CR-39 by ArF laser irradiation

    Science.gov (United States)

    Shakeri Jooybari, B.; Afarideh, H.; Lamehi-Rachti, M.; Ghergherehchi, M.

    2015-03-01

    In this work, chemical properties, surface modification, and micro structures formation on ablated polyallyl di-glycol carbonate (CR-39) polymer by ArF laser irradiation (λ = 193 nm) at various fluences and pulse number were investigated. CR-39 samples have been irradiated with an ArF laser (193 nm) at a repetition rate of 1 Hz. Threshold fluence of ablation and effective absorption coefficient of CR-39 were determined. Conical microstructures (Taylor cone) formed on laser-ablated CR-39 exhibit: smooth, Taylor cone shape walls and sharp tips together with interference and well defined fringe-structure with a period of 230 nm, around cone base. Mechanism of cone formation and cone evolution of CR-39 ablated surface were investigated by change of fluences (at a given pulse number) and pulse number (at a given fluence). Cone height, cone base, and region of interface were increased in micrometer steps by increasing the total fluence. Depression on the base of the cone and the circular fringe were simulated. FTIR spectra were measured and energy dispersive x-ray analysis of irradiated and un-irradiated samples was performed.

  18. Ablation and cone formation mechanism on CR-39 by ArF laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Shakeri Jooybari, B., E-mail: baninshakery@gmail.com, E-mail: hafarideh@aut.ac.ir [Department of Energy Engineering and Physics, Amirkabir University of Technology, P.O. Box 15875-4413, Tehran, Islamic Republic of Iran (Iran, Islamic Republic of); Nuclear Science and Technology Research Institute NSRT, Tehran (Iran, Islamic Republic of); Afarideh, H., E-mail: baninshakery@gmail.com, E-mail: hafarideh@aut.ac.ir [Department of Energy Engineering and Physics, Amirkabir University of Technology, P.O. Box 15875-4413, Tehran, Islamic Republic of Iran (Iran, Islamic Republic of); Lamehi-Rachti, M. [Nuclear Science and Technology Research Institute NSRT, Tehran (Iran, Islamic Republic of); Ghergherehchi, M. [Department of Energy Engineering and Physics, Amirkabir University of Technology, P.O. Box 15875-4413, Tehran, Islamic Republic of Iran (Iran, Islamic Republic of); College of Information and Communication Engineering, Sungkyunkwan University, Suwon (Korea, Republic of)

    2015-03-07

    In this work, chemical properties, surface modification, and micro structures formation on ablated polyallyl di-glycol carbonate (CR-39) polymer by ArF laser irradiation (λ = 193 nm) at various fluences and pulse number were investigated. CR-39 samples have been irradiated with an ArF laser (193 nm) at a repetition rate of 1 Hz. Threshold fluence of ablation and effective absorption coefficient of CR-39 were determined. Conical microstructures (Taylor cone) formed on laser-ablated CR-39 exhibit: smooth, Taylor cone shape walls and sharp tips together with interference and well defined fringe-structure with a period of 230 nm, around cone base. Mechanism of cone formation and cone evolution of CR-39 ablated surface were investigated by change of fluences (at a given pulse number) and pulse number (at a given fluence). Cone height, cone base, and region of interface were increased in micrometer steps by increasing the total fluence. Depression on the base of the cone and the circular fringe were simulated. FTIR spectra were measured and energy dispersive x-ray analysis of irradiated and un-irradiated samples was performed.

  19. Application of optical tweezers and excimer laser to study protoplast fusion

    Science.gov (United States)

    Kantawang, Titirat; Samipak, Sompid; Limtrakul, Jumras; Chattham, Nattaporn

    2015-07-01

    Protoplast fusion is a physical phenomenon that two protoplasts come in contact and fuse together. Doing so, it is possible to combine specific genes from one protoplast to another during fusion such as drought resistance and disease resistance. There are a few possible methods to induce protoplast fusion, for example, electrofusion and chemical fusion. In this study, chemical fusion was performed with laser applied as an external force to enhance rate of fusion and observed under a microscope. Optical tweezers (1064 nm with 100X objective N.A. 1.3) and excimer laser (308 nm LMU-40X-UVB objective) were set with a Nikon Ti-U inverted microscope. Samples were prepared by soaking in hypertonic solution in order to induce cell plasmolysis. Elodea Canadensis and Allium cepa plasmolysed leaves were cut and observed under microscope. Concentration of solution was varied to induce difference turgor pressures on protoplasts pushing at cell wall. Free protoplasts in solution were trapped by optical tweezers to study the effect of Polyethylene glycol (PEG) solution. PEG was diluted by Ca+ solution during the process to induced protoplast cell contact and fusion. Possibility of protoplast fusion by excimer laser was investigated and found possible. Here we report a novel tool for plant cell fusion using excimer laser. Plant growth after cell fusion is currently conducted.

  20. Measurement and evaluation methods for beam characterization of commercial excimer lasers

    Science.gov (United States)

    Albrecht, Hans Stephen; Rebhan, Ulrich; Mann, Klaus R.; Ohlenbusch, J.

    1996-11-01

    This paper describes the specific requirements for measurement of excimer laser beam profiles for standardized characterization 'of commercial excimer lasers. A corresponding measurement system is presented which allows a simultaneous characterization of energy density distribution in the near field as well as in the focal plane of a lens (far field). Specially adapted UV-cameras make possible sings pulse diagnostic. Beam widths are calculated from the digitized camera data by different methods corresponding to the proposals of ISO 11146 (second moment, moving knife edge, and moving slit) and the results are compared. In particular, the influence of background signals as well as the typical shape of energy density distribution in the near field to the determined beam widths are analyzed.

  1. Ablation of hard dental tissues with an ArF-pulsed excimer laser

    Science.gov (United States)

    Neev, Joseph; Raney, Daniel; Whalen, William E.; Fujishige, Jack T.; Ho, Peter D.; McGrann, John V.; Berns, Michael W.

    1991-06-01

    The interaction of 15 ns pulses from an ArF excimer laser with hard dental tissue was investigated for the purpose of obtaining practical information on the ablation process. Dark field fast photography utilizing an auxiliary, 15 ns Nd:Yag laser 'probe', was used to study the ablation plume dynamics as a function of time, luminescence were studied at different fluence levels and prr. Dentin ablation was found to be about four times as efficient as ablation of enamel in the higher fluence levels tested (> 10 J/cm2) and about twice as efficient as the ablation in the lower fluence regime (approximately equals 1 J/cm2). The dentin etch depth per pulse was found to increase exponentially with fluence (at least up to the tested level of 11 J/cm2), while in enamel the etch depth per pulse appears to increase logarithmically with fluence. Dentin ablation yields a larger, more dense plume which can be ejected (depending on the fluence level) to a height of several millimeters above the surface with observed ejection velocity in access of 1200 m/s. The dentin plume consisted of a relatively uniform particle size distribution (0.1 micrometers to 10 micrometers in diameter). Enamel ablation, on the other hand, yields a smaller observed ejection velocities (about 800 m/s), and a much smaller plume of fine particles (about 0.1 micrometers in diameter) and gases, confined to within 0.5 mm of the surface. In addition, an even smaller amount of highly non-uniform debris, (from ten to several hundred micrometers in size) is observed to be ejected to higher levels, and reach roughly half the height of the corresponding dentin plume for similar fluence levels. Although both dentin and enamel yield lower ablation efficiencies at 1 Hz, no significant difference is detected between the ablation efficiency at 5 Hz and ablation 10 Hz prr. Both materials remained within 20 degree(s)C of room temperature even at fluences as high as 20 J/cm2 and prr as high as 10 Hz for enamel and 20 Hz for

  2. Numerical simulation and optimizational calculations of KrF excimer lasers for controlled fusion

    International Nuclear Information System (INIS)

    The paper deals with the problems of numerical simulation of large-aperture excimer lasers, designated for application as drivers in laser thermonuclear reactor with inertial plasma confinement. Results of numerical optimization of the process of energy contribution of a heavy-current electron beam to inert gas are presented. These results and results of investigation of active medium kinetics and energy measurement were used for optimizational calculations of KrF-laser parameters with respect to output radiation energy and total efficiency. 8 refs.; 10 figs

  3. COMPUTER-AIDED DECISION SYSTEM FOR REFRACTIVE SURGERIES WITH EXCIMER LASER

    OpenAIRE

    Rawan Baroudy; Bassam Lala

    2014-01-01

    124 patients (248 eyes) who intended to refractive surgery by Excimer laser were studied to implement our goal of this study which is design and operate a computer-aided decision system for optimal choosing the best refractive surgery based on patient needs, Starting from corneal topography and aberration images, using RGB and HSI color spaces and decision tree. The system also can calculate percent of vision correction, ablation and residual stroma with high precision. This highly important ...

  4. Characterization of microstructures induced in the workpiece of aluminum alloy by excimer laser micromachining

    Energy Technology Data Exchange (ETDEWEB)

    Wu Ye [Shenzhen Key Lab of Laser Engineering, College of Electronic Science and Technology, Shenzhen University, Shenzhen 518060 (China); Li, Irene Ling, E-mail: liling@szu.edu.cn [Shenzhen Key Lab of Laser Engineering, College of Electronic Science and Technology, Shenzhen University, Shenzhen 518060 (China); Fu Ling; Zhai Jianpang; Ruan Shuangchen [Shenzhen Key Lab of Laser Engineering, College of Electronic Science and Technology, Shenzhen University, Shenzhen 518060 (China)

    2009-09-15

    Excimer laser emitting at 248 nm is applied to produce microstructures on the surface of aluminum alloy. The surface morphology shows that hotspots and thermal fluidic structures both come to light. Two possible mechanisms of hotspots formation are proposed: near-field diffraction and interference, and extremely fast rapid thermal annealing. And for the formation of thermal fluidic pattern structure, a thin film model is applied.

  5. Expression of Epidermal c-Kit+ of Vitiligo Lesions Is Related to Responses to Excimer Laser

    Science.gov (United States)

    Park, Oun Jae; Han, Ji Su; Lee, Sang Hyung; Park, Chan-Sik; Won, Chong Hyun; Lee, Mi Woo; Choi, Jee Ho

    2016-01-01

    Background The survival and growth of melanocytes are controlled by the binding of stem cell factor to its cell surface receptor c-kit+ (CD117). We have observed that c-kit+ melanocytes existed in some lesions of vitiligo, while Melan A+ cells were absent. Objective To verify possible relation between c-kit+ expression and treatment response in non-segmental vitiligo lesions Methods Skin biopsies were done from the center of the 47 lesions from the 47 patients with non-segmental vitiligo. Expression of c-kit+ and Melan A, and amounts of melanin in the epidermis were assessed in each lesion, and treatment responses to excimer laser were evaluated. Results Thirty-five of the 47 lesions (74.5%) had c-kit+ phenotypes. There was significant difference of c-kit staining value between good responders in 3 months of excimer laser treatment (average of 24 sessions) and the others. Conclusion c-Kit expression in vitiliginous epidermis may be related to better treatment responses to excimer laser. PMID:27489428

  6. Photoacoustic injury and bone healing following 193nm excimer laser ablation.

    Science.gov (United States)

    Lustmann, J; Ulmansky, M; Fuxbrunner, A; Lewis, A

    1992-01-01

    The argon-fluoride excimer laser was investigated as a cutting-ablating tool for bone surgery. A total of 52 rats were divided into two experimental groups and two control groups. In one experimental group cortical bone defects were made; in another experimental group defects penetrating into the medullary space were performed. In the two control groups similar defects were achieved using water-cooled carbide burs. The rats were sacrificed on each of the 3, 7, 10, 20, 30, and 40 postoperative day. The cortical bone, the medullary space, and the extrabony tissue were examined by means of light microscopy. In both experimental groups, bone damage, represented by osteocyte destruction, extended to 1,050-1,450 microns ahead from the irradiated site, and bone healing was very much impaired. In the control groups no histological changes could be identified and bone healing appeared to be within normal limits. We believe this extensive bone damage, following 193 nm irradiation, to be a result of photoacoustic waves propagating in the bone following each pulse. In view of our results we feel that excimer lasers presently in use are not suitable for bone surgery. This problem of photoacoustic damage can be overcome in one of two ways: by designing a CW excimer laser or by reducing the pulse width to the picosecond regime. PMID:1495367

  7. A study of structure formation on PET, PBT, and PS surfaces by excimer laser ablation

    Science.gov (United States)

    Kim, Jongdae

    Usually polymer surface treatment is performed to modify surface layers by inserting some functional group and/or by inducing roughness on surfaces to improve their wettability, printability, and adhesion to other polymers or metals. In this work, different polymer surfaces were treated using an excimer laser (LPX 240i, Lambda Physik). Polystyrene, polyethylene terephtalate, and polybutylene terephtalate were chosen as model materials for this study. Films were made by cast film processing and stretched with biaxial stretching machine. With excimer laser treatment on polymer surfaces, it was found that we could produce 1--2 micron size structures depending on material properties and film processing conditions. Materials with lower UV absorption coefficient produced double digit micron size structures, while those with higher UV absorption coefficients produced single digit micron size structures. In all these cases the structures formed only on stretched films. In addition to those microstructure developments, the determination of ablation threshold fluence was of interest mainly for understanding fundamentals of ablation behavior and technical applications. In this study, ablation thresholds were measured by various methods including ablation depth, ablation weight, and ablation sound level measurements. Among these methods, we confirmed that the measurement by ablation sound level gives the most reliable results, because this method is based on single pulse ablation. To understand the ablation phenomenon, and how microstructures can be developed during ablation, different material processing and excimer laser conditions were chosen for experimentation. During our experiments, we observed incubation phenomenon during laser ablation and showed that this incubation was significant for materials with low UV absorption coefficients. Based on UV absorption value change after excimer laser irradiation, we proposed a mechanism to explain the ablation of PS films. From

  8. Precision drilling of fused silica with 157-nm excimer laser radiation

    Science.gov (United States)

    Temme, Thorsten; Ostendorf, Andreas; Kulik, Christian; Meyer, Klaus

    2003-07-01

    μFor drilling fused silica, mechanical techniques like with diamond drills, ultrasonic machining, sand blasting or water jet machining are used. Also chemical techniques like laser assisted wet etching or thermal drilling with CO2-lasers are established. As an extension of these technologies, the drilling of micro-holes in fused silica with VUV laser radiation is presented here. The high absorption of the 157 nm radiation emitted by the F2 excimer laser and the short pulse duration lead to a material ablation with minimised impact on the surrounding material. Contrary to CO2-laser drilling, a molten and solidified phase around the bore can thus be avoided. The high photon energy of 7.9 eV requires either high purity nitrogen flushing or operation in vacuum, which also effects the processing results. Depending on the required precision, the laser can be used for percussion drilling as well as for excimer laser trepanning, by applying rotating masks. Rotating masks are especially used for high aspect ratio drilling with well defined edges and minimised debris. The technology is suitable particularly for holes with a diameter below 200 μm down to some microns in substrates with less than 200 μm thickness, that can not be achieved with mechanical methods. Drilling times in 200 μm fused silica substrates are in the range of ten seconds, which is sufficient to compete with conventional methods while providing similar or even better accuracy.

  9. Surface ablation of PLLA induced by KrF excimer laser

    International Nuclear Information System (INIS)

    The surface characterization of PLLA (poly-L-lactic-acid) and its ablation due to excimer laser treatment is introduced in this paper. The main focus is to determine surface wettability and morphology changes in combination with changes of surface chemistry. The ablation loss and the determination of ablation threshold were used to study the biopolymer stability when treated to different laser fluences and pulse counts. The surface polarity was estimated using goniometry. AFM (atomic force microscopy) was used to determine the polymer surface morphology and roughness. The excimer laser has a strong effect on the polymer ablation. The thickness loss is strongly dependent on the laser fluence and number of pulses. For the fluences up to 30 mJ cm−2 and 6000 pulses achieved ablation about 5 μm. The glass transition temperature and melting point were determined for the pristine and laser treated films. The increasing pulsed laser fluence leads to the major changes in roughness and morphology. The surface chemistry depends strongly on number of laser pulses.

  10. Surface ablation of PLLA induced by KrF excimer laser

    Energy Technology Data Exchange (ETDEWEB)

    Slepička, P., E-mail: petr.slepicka@vscht.cz [Department of Solid State Engineering, Institute of Chemical Technology Prague, 166 28 Prague (Czech Republic); Michaljaničová, I. [Department of Solid State Engineering, Institute of Chemical Technology Prague, 166 28 Prague (Czech Republic); Sajdl, P. [Department of Power Engineering, Institute of Chemical Technology, 166 28 Prague (Czech Republic); Fitl, P. [Department of Physics and Measurements, Faculty of Chemical Engineering, Institute of Chemical Technology Prague, 166 28 Prague (Czech Republic); Švorčík, V. [Department of Solid State Engineering, Institute of Chemical Technology Prague, 166 28 Prague (Czech Republic)

    2013-10-15

    The surface characterization of PLLA (poly-L-lactic-acid) and its ablation due to excimer laser treatment is introduced in this paper. The main focus is to determine surface wettability and morphology changes in combination with changes of surface chemistry. The ablation loss and the determination of ablation threshold were used to study the biopolymer stability when treated to different laser fluences and pulse counts. The surface polarity was estimated using goniometry. AFM (atomic force microscopy) was used to determine the polymer surface morphology and roughness. The excimer laser has a strong effect on the polymer ablation. The thickness loss is strongly dependent on the laser fluence and number of pulses. For the fluences up to 30 mJ cm{sup −2} and 6000 pulses achieved ablation about 5 μm. The glass transition temperature and melting point were determined for the pristine and laser treated films. The increasing pulsed laser fluence leads to the major changes in roughness and morphology. The surface chemistry depends strongly on number of laser pulses.

  11. Electrochemical micromachining of titanium using laser oxide film lithography: excimer laser irradiation of anodic oxide

    Energy Technology Data Exchange (ETDEWEB)

    Chauvy, P.-F.; Hoffmann, P.; Landolt, D

    2003-04-30

    In electrochemical micromachining using oxide film laser lithography (OFLL), the pattern is formed by laser irradiation of an anodic oxide film. On the irradiated areas of the film the underlying metal is then selectively dissolved in an appropriate electrolyte, the non-irradiated oxide acting as a mask. The physical interactions of 308 nm XeCl excimer laser radiation with anodically formed oxide films on titanium were studied using single pulse irradiation at varying fluence and two different pulse durations. The irradiated surfaces were characterized by secondary electron microscopy (SEM), Auger electron spectroscopy (AES) profiling and X-ray-induced photoelectron spectroscopy (XPS), additionally, their electrochemical dissolution behaviour in an electropolishing electrolyte was evaluated. Numerical simulation was applied to the estimation of the temperature profiles at the surface of the irradiated samples. Results suggest that depending on irradiation conditions different mechanisms may be responsible for the loss of the protective properties of the oxide film. The creation of a Ti(O) solid solution resulting from diffusion of oxygen from the film into the underlying molten metal was shown to be effective at high fluences. The loss of protective properties observed at lower fluences was tentatively attributed to the creation of ionic defects in the oxide by a photolytic process.

  12. The development and progress of XeCl Excimer laser system

    Science.gov (United States)

    Zhang, Yongsheng; Ma, Lianying; Wang, Dahui; Zhao, Xueqing; Zhu, Yongxiang; Hu, Yun; Qian, Hang; Shao, Bibo; Yi, Aiping; Liu, Jingru

    2015-05-01

    A large angularly multiplexed XeCl Excimer laser system is under development at the Northwest Institute of Nuclear Technology (NINT). It is designed to explore the technical issues of uniform and controllable target illumination. Short wavelength, uniform and controllable target illumination is the fundamental requirement of high energy density physics research using large laser facility. With broadband, extended light source and multi-beam overlapping techniques, rare gas halide Excimer laser facility will provide uniform target illumination theoretically. Angular multiplexing and image relay techniques are briefly reviewed and some of the limitations are examined to put it more practical. The system consists of a commercial oscillator front end, three gas discharge amplifiers, two electron beam pumped amplifiers and the optics required to relay, encode and decode the laser beam. An 18 lens array targeting optics direct and focus the laser in the vacuum target chamber. The system is operational and currently undergoing tests. The total 18 beams output energy is more than 100J and the pulse width is 7ns (FWHM), the intensities on the target will exceed 1013W/cm2. The aberration of off-axis imaging optics at main amplifier should be minimized to improve the final image quality at the target. Automatic computer controlled alignment of the whole system is vital to efficiency and stability of the laser system, an array of automatic alignment model is under test and will be incorporated in the system soon.

  13. Green synthesis of selenium nanoparticles by excimer pulsed laser ablation in water

    Directory of Open Access Journals (Sweden)

    O. Van Overschelde

    2013-10-01

    Full Text Available Pure selenium nanoparticles were successfully synthesized by Liquid Phase - Pulsed Laser Ablation (LP-PLA in de-ionized water. Excimer laser (248 nm operating at low fluence (F ∼ 1 J/cm2 was used to generate colloidal solutions of selenium nanoparticles. The obtained selenium nanoparticles were characterized by UV-visible spectroscopy, Raman spectroscopy, Dynamic Light Scattering, and Transmission Electron Microscopy. We describe the multi-modal size distributions generated and use the centrifugation method to isolate the smallest nanoparticles (∼60 nm in diameter.

  14. Flow quantification of the non-occlusive excimer laser-assisted EC-IC bypass

    International Nuclear Information System (INIS)

    Background. For six years, we used the excimer laser-assisted non-occlusive anastomosis technique for high-flow revascularization of the brain in patients with either nonclippable and noncoilable giant aneurysms of the internal carotid or basilar artery or progressive stroke associated with occlusive disease of the internal carotid artery. The aim of this study is to assess the blood flow capacity of this type of extra-intracranial bypass and its haemodynamic behavior over time. Methods. Twenty-six patients with a giant aneurysms and 8 patients with occlusive disease of the internal carotid artery were treated with the non-occlusive excimer laser assisted EC-IC bypass. Intra-operatively, direct measurements of flow in the EC-IC bypass were performed in all patients (Transonic Systems, Inc., Ithaca, NY). Postoperatively, follow up measurements of flow were performed with MR angiography in 14 patients with a giant aneurysm after occluding the internal carotid artery, and 7 patients with occlusive carotid disease. Results. The mean flow in the laser assisted bypasses in the group of patients with a giant aneurysm was 158 ml/min after ligation or balloon occlusion of the ICA. The mean flow of the laser assisted bypass in the group of patients with ICA occlusive disease was 130 ml/min. A comparison with data on flow capacity of conventional EC IC bypasses is made. A demonstrated increase of flow in the bypass during follow up is discussed from a haemodynamic point of view. Conclusions. The results of this study demonstrate that the flow capacity of the non-occluding excimer laser assisted bypass is much higher than the capacity of the conventional, more peripherally located conventional EC IC bypass, and should therefore be denoted as high-flow EC IC bypass. Consequently, this type of bypass can be a powerful and safe tool in new revascularization strategies. (author)

  15. Offset-gated poly-Si TFTs using in-situ fluorine passivation and excimer laser doping

    CERN Document Server

    Jung, S H; Yoo, J S; Han, M K

    2000-01-01

    A new low-temperature poly-Si thin film transistor (TFT) fabrication method employing in-situ fluorine passivation and excimer-laser doping is proposed to fabricate offset-gated poly-Si TFTs. In the new process, the crystallization, the in-situ fluorine passivation of the active layer, and the doping of the source/drain region are performed simultaneously with only one step of excimer laser annealing while the conventional fabrication method requires two laser annealing steps. Employing phosphosilicate glass (PSG) films as a diffusion source, we successfully accomplished excimer laser doping. The subthreshold and the on-state characteristics of the device with in-situ fluorine passivation were considerably improved. This improvement was due to the fluorine passivation effects, which cured dangling bonds and strained bonds in the poly-Si channel, the offset region, and the SiO sub 2 /poly-Si interface.

  16. Excimer laser coronary angioplasty: experience with a prototype multifibre catheter in patients with stable angina pectoris.

    Science.gov (United States)

    Kochs, M; Haerer, W; Eggeling, T; Hoeher, M; Schmidt, A; Hombach, V

    1992-03-01

    Percutaneous excimer laser coronary angioplasty (ELCA) was performed in a first group of 20 patients with stable angina pectoris caused by significant coronary stenosis, and long-term follow-up was evaluated. Prototype 4 to 5.5 French multifibre catheters with 18-20 quartz fibres of 100 microns diameter, concentrically arranged around a central lumen for taking up a guide wire, were coupled to a commercial XeCl excimer laser. Energy was delivered at a wavelength of 308 nm with a pulse duration of 60 or 120 ns. Operating at a repetition rate of 20 Hz, mean energy transmission was 13.4 +/- 6.8 mJ per pulse. In all but one patient the lesion could be passed by the catheter. Percent diameter stenosis decreased from 77.1 +/- 10.8% to 53.1 +/- 11.8% after ELCA. Complications were frequently observed, intracoronary thrombus formation in eight instances, dissection in six patients and spasm in five cases, causing total vessel occlusion in five procedures. All complications could be managed efficaciously by thrombolytic and vasodilating drugs and/or balloon angioplasty. Subsequent PTCA was performed in case of complication or insufficient stenosis reduction after ELCA in 18 patients with adequate results (residual stenosis, 28.5 +/- 10.2%). Long-term follow-up angiography, which could be performed in 16 of 19 laser treatments, demonstrated significant restenosis in only three patients. Our preliminary results suggest that, using ELCA, ablation of atherosclerotic lesions is feasible in most cases. However, compared with PTCA, stenosis reduction is significantly less, and the acute complication rate is much higher. Thus, further improvements of the catheter system are necessary in order to realize the advantages of excimer laser ablation, which can be demonstrated by experimental studies. PMID:1597220

  17. XeCl excimer laser with new prism resonator configurations and its performance characteristics

    International Nuclear Information System (INIS)

    New resonator cavity configurations, namely, the prism resonator and unstable prism resonator, are demonstrated for the first time in an excimer (XeCl) laser with interesting and novel results. High misalignment tolerance ∼50 mrad is achieved with considerably reduced beam divergence of less than ∼1 mrad without reduction in output power capabilities of the laser. The misalignment tolerance of ∼50 mrad is a dramatic improvement of ∼25 times compared to ∼2 mrad normally observed in standard excimer laser with plane-plane cavity. Increase in depth of focus from 3 mm to 5.5 mm was also achieved in case of prism resonator configuration with an improvement of about 60%. Unstable prism resonator configuration is demonstrated here in this paper with further reduction in beam divergence to about 0.5 mrad using plano-convex lens as output coupler. The misalignment tolerance in case of unstable prism resonator was retained at about 30 mrad which is a high value compared to standard unstable resonators. The output beam spot was completely filled with flat-top profile with prism resonator configurations, which is desired for various material processing applications. Focusing properties and beam divergence in case of prism resonator have been investigated using SEM (scanning electron microscope) images. SEM images of the focused spot size (∼20 μm holes) on metal sheet indicate beam divergence of about 0.05 mrad which is about 1.5 times diffraction limit. Energy contained in this angle is thus sufficient for micro-machining applications. Clean and sharp edges of the micro-holes show high pointing stability with multiple shot exposures. Such characteristics of the excimer laser system will be extremely useful in micro-machining and other field applications

  18. Preparation of PZT thin films on YBCO electrodes by KrF excimer laser ablation technique

    International Nuclear Information System (INIS)

    Pb(ZrXTi1-X)O3 (PZT) films have excellent ferroelectric, optical, piezoelectric, and pyroelectric properties. We prepared PZT thin films by the excimer laser ablation technique. A pulsed KrF excimer laser (Lambda Physik LPX305icc, pulse duration of 25 ns, λ=248 nm, 850 mJ Max.) was used to ablate the bulk targets. We investigated the influence of bottom electrode materials on the characteristics of the PZT thin films prepared on Pt and YBCO underlayers. The X-ray diffraction (XRD) patterns showed that the PZT films prepared with a laser fluence of 2 Jcm-2 on YBCO/MgO(100) substrate at a wide temperature range of 550-680 C have a perovskite (001) structure. At the same laser fluence, the PZT films prepared on Pt/MgO(100) substrate have a perovskite (001) structure only at 650 C. The polarization-electric field (P-E) characteristics and fatigue properties of PZT thin films were measured by the Sawyer-Tower circuit. The remnant polarization and coercive field have been found to be Pr=15 μC cm-2, 30 μC cm-2 and Ec=200 kV cm-1, 100 kV cm-1 for Au/PZT/Pt/MgO and Au/PZT/YBCO/MgO correspondingly. The remnant polarization of Au/PZT/YBCO/MgO thin film was reduced to one-half after about 108 cycles of switching. (orig.)

  19. Random noise can help to improve synchronisation of excimer laser pulses

    CERN Document Server

    Mingesz, Robert; Gingl, Zoltan; Mellar, Janos

    2015-01-01

    Recently we have reported on a compact microcontroller-based unit developed to accurately synchronise excimer laser pulses (Robert Mingesz et al, Fluct. Noise Lett. 11, 1240007 (2012), DOI: 10.1142/S021947751240007X, arXiv:1109.2632). We have shown that dithering based on the random jitter noise plus pseudorandom numbers can be used in the digital control system to radically reduce the long-term drift of the laser pulse from the trigger and to improve the accuracy of the synchronisation. In this update paper we present our new experimental results obtained by the use of the delay controller unit to tune the timing of a KrF excimer laser as an addition to our previous numerical simulation results. The hardware was interfaced to the laser using optical signal paths in order to reduce sensitivity to electromagnetic interference and the control algorithm tested by simulations were applied in the experiments. We have found that the system is able to reduce the delay uncertainty very close to the theoretical limit ...

  20. KrF excimer laser driver for nuclear fusion

    International Nuclear Information System (INIS)

    Super-ASHURA, six beams KrF laser system, was accomplished by developing the main amplifier (60 cm caliber, 2 m amplifier length) with 38 KJ excited input energy, 10% internal efficiency, 2.5% total efficiency and 2.7 KJ total output energy. A laser pulse compressive technique using induced Raman amplifier in the gas attained to from 20 ns to 4 ns pulse width (74% transformation efficiency) by the multiple optical path forward Raman amplifier and from 20 ns to 100 ps or less of high magnification compression by the strong saturation backward amplifier. The structure of plasma from KrF laser beam was determined by measuring the electron density and the temperature of plasma. (S.Y.)

  1. Development of a compact and reliable repetitively pulsed Xe Cl (308 nm) excimer laser

    Indian Academy of Sciences (India)

    N S Benerji; N Varshnay; J K Mittal

    2013-02-01

    Development and operation characteristics of a repetitively pulsed UV spark pre-ionized XeCl(Xenon Chloride) excimer laser is described. The laser uses discharge pumped C–C charge transfer excitation. A compact gas circulation loop was adopted to achieve high repetition rate operation. The laser generates optical pulses of energy 150 mJ at 150 Hz reliably. The electrical to optical conversion efficiency obtained is 1%. The laser pulse duration is ∼8 nS (FWHM). The single fill gas lifetime have been found to be 2 × 106 shots for 20% reduction of energy without any halogen injection. The system is compact and reliable.

  2. Interaction of ArF laser with dental hard tissue (AEM Study

    Directory of Open Access Journals (Sweden)

    Abbas Majdabadi

    2016-07-01

    Full Text Available Background and Aims: Nowadays lasers are used as alternatives to the tooth preparation because of reducing pain and bloodshed. The aim of this study was to observe the effect of ArF laser on the dental hard tissues. Materials and Methods: For this research human molar teeth with no caries or dental restoration and enamel cracks were used. Irradiation laser energies were taken 95, 70 and 50 mJ for enamel and 80, 70 and 50 mJ for dentine. Then, for each of energy values pulse numbers (repetition rate were adjusted at 200, 400, 600, 800, 1000 and 1500. Ablation was carried out without water spray on both enamel and dentine. Finally, the dimensions of ablated areas were measured by using a camera connected to the computer and results were applied in graphs. Results: For each energy value, the ablation dimension increased by increasing pulse numbers. Ablation depth in dentine was more than that of for enamel. Trends of graphs for dentine and enamel were the same. SEM images of ablations by 95 mJ energy on enamel and 80 mJ energy on dentine showed sharp edges. Conclusion: Ablation depths increased by increasing pulse numbers, for each energy level. However, this increase was not that as expected, because the lack of water spray while irradiating.

  3. Angular velocity spread of relativistic photoelectrons induced by excimer laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Kawai, M.; Kawamura, Y.; Toyoda, K.

    1984-12-15

    The angular velocity spread of relativistic photoelectrons induced by a pulsed excimer laser was measured. The energy, the current density, and the pulse duration of the accelerated photoelectron were 0.34 MeV, 0.5 A/cm/sup 2/, and 20 ns, respectively. (The method of measurement is based on measuring Larmor radius which corresponds to the transverse component of the electron velocity.)= The angular velocity spread ..beta../sub perpendicular//..beta../sub parallel/ was found to be less than 8 x 10/sup -3/, which means that the energy component due to ..beta../sub perpendicular/ was as small as < or approx. =17 eV.

  4. COMPUTER-AIDED DECISION SYSTEM FOR REFRACTIVE SURGERIES WITH EXCIMER LASER

    Directory of Open Access Journals (Sweden)

    Rawan Baroudy

    2014-01-01

    Full Text Available 124 patients (248 eyes who intended to refractive surgery by Excimer laser were studied to implement our goal of this study which is design and operate a computer-aided decision system for optimal choosing the best refractive surgery based on patient needs, Starting from corneal topography and aberration images, using RGB and HSI color spaces and decision tree. The system also can calculate percent of vision correction, ablation and residual stroma with high precision. This highly important transdisciplinary topic combines aspects from biosystems (human visual system, image acquisition and processing and information management (databases.

  5. Optical coherence tomography following percutaneous coronary intervention with Excimer laser coronary atherectomy

    Energy Technology Data Exchange (ETDEWEB)

    Rawlins, John, E-mail: john.rawlins@doctors.net.uk; Talwar, Suneel; Green, Mark; O’Kane, Peter

    2014-01-15

    The indications for Excimer laser coronary atherectomy (ELCA) have been refined in modern interventional practice. With the expanding role for optical coherence tomography (OCT) providing high-resolution intra-coronary imaging, this article examines the appearance of the coronary lumen after ELCA. Each indication for ELCA is discussed and illustrated with a clinical case, followed by detailed analysis of the OCT imaging pre and post ELCA. The aim of the article is to provide information to interventional cardiologists to facilitate decision making during PCI, when ELCA has been used as part of the interventional strategy.

  6. A coaxial e-beam excitation system for high power excimer lasers

    OpenAIRE

    Oomen, G.L.; Witteman, W.J.

    1980-01-01

    We report the successful operation of a medium scale, high current density (230 A/cm2) coaxial e-beam device for excimer laser pumping. Construction, input energy, and output energy are described. Compared with a one-sided transversal system the specific input energy is more than three times higher. This is attributed to the absence of a foil support structure, a better concentration of the energy into the gain volume, and an extra contribution of electrons reflected by the potential field. M...

  7. Excimer laser induced melting and decomposition of technical ceramic surfaces and their properties

    OpenAIRE

    Grossmann, J.; Emmel, A.; Schubert, E.; Bergmann, H

    1993-01-01

    The chemical, structural and topographical changes after the irradiation of technical oxide (Al2O3, ZrO2) and nonoxide ceramics (SiC, Si3N4) with a XeCl-Excimer Laser were studied as function of the applied energy density and number of pulses. The silicon-based nonoxide ceramics decomposed during a temperature and pressure induced process and an adherent up to 1,5 µm thick crystalline Si-layer remained on top of the specimen surface. In contrast, the oxide ceramics underwent a melting and rap...

  8. Important technological problems with stable operation of electron beam pumped KrF excimer laser amplifier

    CERN Document Server

    Ma Wei Yi; Hu Feng Ming; Shan Yu Sheng; Wang Nai Yan

    2002-01-01

    Some important technological problems with stable operation of the two-side electron beam pumped main amplifier used in the 'Heaven-1' high power KrF excimer laser system are described. They are the problems of the electric breakdown of the insulator support for water dielectric transmission lines, anode foil installation of large area electron beam diode, shape of Hibachi ribs that contact the pressure foil, and formation of diode post pulses and their damage to the anode foil and cathode emitter. Emphasis is put on the effect of different main-switch breakdown times on diode post pulses and the determination of the optimal breakdown time

  9. Ablation of bone and polymethylmethacrylate by an XeCl (308 nm) excimer laser

    Energy Technology Data Exchange (ETDEWEB)

    Yow, L.; Nelson, J.S.; Berns, M.W.

    1989-01-01

    One of the main problems in orthopaedics is the surgical removal of hard substances, such as bone and polymethylmethacrylate (PMMA). Such materials are often very difficult to remove without mechanical trauma to the remaining tissue. This study investigated the feasibility of the ultraviolet 308 nm excimer laser in the ablation of these materials. The beam was delivered through a 1 mm-diameter fiber optic at 40 Hz with energy densities at the target surface of 20-80 J/cm2 per pulse. The goal of the study was to establish the ideal dosimetry for removing bone and PMMA with minimum trauma to the adjacent tissue. Histology revealed that the 308 nm laser effectively removed bone leaving a thermal damage zone of only 2-3 microns in the remaining tissue. Increasing the energy per pulse gave correspondingly larger and deeper cuts with increasing zones of thermal damage. The excimer laser was also effective in the ablation of PMMA, creating craters in the substrate with a thermal damage zone of 10-40 microns. The debris from both substrates was evaluated.

  10. Amorphous film thickness dependence for epitaxy of perovskite oxide films under excimer laser irradiation

    International Nuclear Information System (INIS)

    We have studied the epitaxial growth of perovskite manganite LaMnO3 (LMO) on SrTiO3(1 0 0) in the excimer laser assisted metal organic deposition process. The LMO was preferentially grown from the substrate surface by the KrF laser irradiation. The study of amorphous LMO film thickness dependence on epitaxial growth under the excimer laser irradiation revealed that the photo-thermal heating effect strongly depended on the amorphous film thickness due to a low thermal conductivity of amorphous LMO: the ion-migration for chemical bond-forming at the reaction interface would be strongly enhanced in the amorphous LMO film with the large film thickness about 210 nm. On the other hand, the photo-chemical effect occurred efficiently for the amorphous film thickness in the range of 35-210 nm. These results indicate that the epitaxial growing rate was dominated by the photo-thermal heating after the photo-chemical activation at the growth interface.

  11. Tribology and hardness of excimer-laser-processed titanium layers on cubic zirconia

    International Nuclear Information System (INIS)

    The authors have examined the wear and friction and surface hardness of excimer-laser-processed Ti layers on cubic zirconia substrates. The film exhibits a complex array of cracking following processing that is related to the crystallographic orientation of the substrate. The friction between the laser-processed layers and both steel and ruby pins is reduced by approximately one-third relative to that of untreated zirconia. In the untreated case, wear is characterized by pin wear and debris, whereas the laser-processed layer wears by film transfer to the pin. The surface hardness of the processed layer is lower than that of both the untreated zirconia and the deposited Ti film. Indentation tests indicate that the surface is brittle following processing

  12. Laser mass spectrometric detection of AlH molecules as collision-free excimer laser photoproducts from aluminum alkyls

    Science.gov (United States)

    Zhang, Y.; Stuke, M.

    1988-08-01

    Aluminum hydride molecules AlH are detected and identified by tunable dye-laser mass spectroscopy as collision-free UV excimer laser photoproducts of the Al alkyls TEA (triethylaluminum (C 2H 5) 3Al) and TIBA (triisobutylaluminum ( i-C 4H 9) 3Al) at 248 and 193 nm. An internal energy distribution analysis of the photoproducts shows only minor vibrational excitation of ν″ = 1 and a Boltzmann-type rotational energy distribution with a temperature of about 0.03 eV, compared to the incoming photon energy of 5.0 or 6.42 eV.

  13. KrF excimer laser driver for nuclear fusion

    International Nuclear Information System (INIS)

    ''Super-ASHURA'', KrF laser driver, was attained to 245J the maximum output energy to 1 pulse and 2.7 kJ total energy by multiple amplification of 12 beams. The internal efficiency is 10% in the local field. With increasing the excitation efficiency by optimizing electron beam diode, about 5 kJ output is expected under the maximum rated operation. Raman amplification used as wave correction showed to increase power with high efficiency and to smooth output beam by introducing crossing configuration of beam into multipass optical forward amplification method. Short pulse with 2J energy and 100 ps pulse width was produced by method of back Raman amplification. Multiplication factor of power increased 30 times. It indicated practical pulse compression using larger energy. (S.Y.)

  14. Aluminium-Induced Crystallization of Silicon Thin Film by Excimer Laser Annealing

    International Nuclear Information System (INIS)

    Polycrystalline silicon (poly-Si) film was fabricated by indirect process of re-crystallization of amorphous silicon (a-Si) thin film. This enhancement process is important to determine the performance of silicon thin film (STF). In this attempt, a fundamental study was carried out to enhance the crystallization of aluminium doped silicon thin film. An a-Si thin film was prepared by low pressure physical vapour deposition (PVD) and doped with 10 % aluminium. The aluminium-induced crystallization (AIC) process was carried out in two sequence steps. Firstly, the amorphous film was annealed by using conventional heat treatment at operating temperature of 350 degree Celsius. Secondly, the poly-Si underwent excimer laser annealing (ELA). The microstructure of thin film was analyzed using atomic force microscope (AFM). The results showed that, the grain size of the a-Si film is increased with the energy density of the excimer laser. The optimum grain size obtained is 129 nm corresponding to energy density of 356 mJ cm-2. (author)

  15. Fabrication of microfilters using excimer laser micromachining and testing of pressure drop

    International Nuclear Information System (INIS)

    The excimer laser micromachining process has displayed numerous advantages as an efficient tool for fabricating 2D and 3D micro-components, such as a high-resolution power (up to sub-micrometer range) and ablation without thermal damage. This work investigates the suitability and limitations of the process for the fabrication of microfilters using excimer laser micromachining. Their successful fabrication requires precise control over the work parameters, and deals with a number of challenges. Three microfilters of mean pore sizes 14.4 µm, 18.3 µm and 25.6 µm but with the same opening ratio, and containing up to 14 000 holes, have been fabricated. Their performance has been assessed by measuring air flow, to capture a trend in pressure drop induced by the filter for varying flow rates. The Reynolds number based on hole diameter covered is 0.0086–0.21. The key findings include development of a successful method of fabrication, a positive correlation between pressure drop and flow rate during testing, and an increase in slope of the pressure curve with a decrease in pore size. The correlation available in the literature shows a large deviation with respect to the experimental data and a new correlation has been proposed. These results are expected to help design microfilters in the very low Reynolds number range

  16. Interaction of 157-nm excimer laser radiation with fluorocarbon polymers

    International Nuclear Information System (INIS)

    Two important fluoropolymers, polytetrafluoroethylene [PTFE-(C2F4)N] and polyvinylidene fluoride [PVDF-(C2H2F2)N], respond to 157-nm laser radiation in dramatically different ways. At fluences sufficient to produce rapid etching, the volatile emissions from PTFE are dominated by (CF2)N fragments. The velocities of the fastest (CF2)N molecules at each mass are consistent with kinetic energies on the order of an electron volt-and change little with fluence. This fluence independence suggests that the velocities are not affected by collisions after emission. To account for the high kinetic energies and the unusual, half-monomer mass distribution, we propose that these fragments are produced by photochemical scission of the polymer backbone, and that a fraction of the excitation energy is delivered to each fragment as kinetic energy. In contrast, the principle neutral species from PVDF is HF. HF is produced by the scission of C-F bonds, followed by chemical reactions with nearby hydrogen. This process is accompanied by the conjugation of backbone C-C bonds. The photochemical cleavage of C-C bonds in PTFE and C-F bonds in PVDF is consistent with the lower C-C bond energy of PTFE.

  17. Laser-induced front side etching of fused silica with XeF excimer laser using thin metal layers

    International Nuclear Information System (INIS)

    Highlights: ► We study laser-induced front side etching of fused silica with a XeF excimer laser. ► Different metal layers as absorber are used. ► The LIFE method allows nm-precision etching with etching depths up to 150 nm. ► The measurement results are compared to the results calculated by a thermal model. - Abstract: Laser-induced front side etching (LIFE) is a method for laser etching of transparent materials using thin absorber layers, e.g., for precision engineering or even optical applications. Aluminium, chromium, molybdenum, silver as well as titanium with various layer thicknesses (5–100 nm) were applied as absorber for etching trenches in fused silica with nanosecond XeF excimer laser radiation. The sample surfaces were processed at laser fluences up to 10 J/cm2 and laser pulse numbers from 1 to 10 pulses. A linear growth of the etching depth at rising laser fluence was found. The film thickness dependency is more complex and mostly influenced by the optical properties of the thin metal films. The influence of the laser fluence, the number of pulses, the absorber material as well as the absorber layer thickness on the etching process, the etching depth, and the surface modification were presented and discussed. A simple model is given that allows the discussion of the etching depth in dependency on the laser fluence and the metal film thickness. The measurements represented a good agreement with the calculated results by a thermal model. The LIFE method allows nm-precision etching of fused silica with etching depths up to 150 nm.

  18. Photorefractive keratectomy for moderate myopia with the VISX and Summit excimer lasers: a retrospective study Ceratectomia fotorrefrativa para correção de miopia moderada com excimer lasers VISX e Summit: estudo retrospectivo

    OpenAIRE

    João C. Ribeiro; Jean M. Ancel; McDonald, Marguerite B; Ray J. Varnell

    2000-01-01

    Purpose: To present photorefractive keratectomy (PRK) results for myopia ranging from -4,00 to - 6,00 diopters performed with the VISX and Summit excimer lasers. Methods: To be eligible for this study, patients had to be 20 to 45 years of age, have -4.00 to -6.00 diopters of myopia and have no more than 1 D of astigmatism. The Summit group was composed of 51 eyes. The baseline preoperative spherical equivalent of myopia was -5.22 ± 0.17 and surgeries were performed with the Excimed UV ...

  19. Excimer laser induced deposition of tungsten from W(CO)6 and WF6

    International Nuclear Information System (INIS)

    ArF laser induced deposition of W from W(CO)6 and WF6 on Si/SiO2 surfaces was investigated. With an in-situ reflectivity measurement the growth of the layer could be monitored during the deposition process. The authors find that the initial stage of layer growth as well as the reflectivity as a function of deposition time depends on the laser fluence and on other deposition parameters. Model calculations, using the optical constants of deposited films, determined by ellipsometry, have been performed to compare the measured reflectivity curves with the calculated curves. The deposited layers have been analyzed by XPS, AES, x-ray diffraction and Raman spectroscopy. Additionally, experiments of direct pattern transfer deposition (via contact mask) with W(CO)6 show the presence of an involved surface process, which by Fresnel diffraction caused structures smaller than 0.5μm

  20. Charge emission from silicon and germanium surfaces irradiated with KrF excimer laser pulses

    International Nuclear Information System (INIS)

    The authors report time-resolved measurements of the emission of positive and negative charge from Si and Ge surfaces irradiated with 248-nm KrF excimer laser pulses. With pulse energies both below and above the melting threshold, the time evolution of the emission currents is complex and strikingly different for Si and Ge. The positive ion emission signal from Ge persists only for the duration of the laser pulse (<60 ns), but in sharp contrast, the signal from Si continues for several microseconds. A tentative suggestion is made that the positive ions encounter a Knudsen layer created just above the surface of the Si target. More refined experiments, coupled with a theoretical effort, are proposed

  1. Excimer laser texturing of natural composite polymer surfaces for studying cell-to-substrate specific response

    Science.gov (United States)

    Dinca, V.; Alloncle, P.; Delaporte, P.; Ion, V.; Rusen, L.; Filipescu, M.; Mustaciosu, C.; Luculescu, C.; Dinescu, M.

    2015-10-01

    Surface modifications of biocompatible materials are among the main factors used for enhancing and promoting specific cellular activities (e.g. spreading, adhesion, migration, and differentiation) for various types of medical applications such as implants, microfluidic devices, or tissue engineering scaffolds. In this work an excimer laser at 193 nm was used to fabricate chitosan-collagen roughness gradients. The roughness gradients were obtained in one step by applying single laser pulses and sample tilting. Fourier transform infrared spectroscopy measurements, atomic force microscopy (AFM), scanning electron microscopy (SEM), and spectro-ellipsometry (SE) were used for sample characterization. The goal is to determine the optimal morpho-chemical characteristics of these structures for in vitro tailoring of protein adsorption and cell behavior. The response induced by the roughness gradient onto various cell lines (i.e. L 929 fibroblasts, HEP G2 hepatocytes, OLN 93 oligodendrocytes, M63 osteoblasts) and bovine serum albumin (BSA) protein absorption was investigated.

  2. Photo-fragmentation of selenium powder by Excimer laser ablation in liquids

    Science.gov (United States)

    Van Overschelde, O.; Guisbiers, G.

    2015-10-01

    Laser ablation in liquids is especially adapted to produce nanoparticles free of any contamination as suited for biological and medical applications. A KrF Excimer laser delivering an UV light at 248 nm and operating at low fluence (F~0.5 J/cm2) was used to irradiate a micro-sized powder of selenium dispersed into a de-ionized water solution. To avoid any agglomeration of the selenium nanoparticles during the irradiation, surfactants (SDS and CTAB) were added to the solution and their efficiency was compared. The concentration of surfactants had to be chosen around the critical micellar concentration to produce small selenium nanoparticles (SDS shows better mono-disperse size distribution compared to CTAB. Finally, photo-fragmentation is found to be more efficient than bulk thermal ablation to produce very small selenium nanoparticles (less than 10 nm).

  3. UV excimer laser photoproducts from absorbing and transparent surfaces covered by aluminum alkyl adsorbates

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Y.; Stuke, M. (Max-Planck-Institut fuer Biophysikalische Chemie, Goettingen (Germany, F.R.))

    1989-06-01

    Neutral atomic and molecular species, generated upon the interaction of UV excimer laser light with Al-alkyl/substrate interfaces, are detected by single-shot dye laser mass spectroscopy. The molecules studied at 308, 248, and 193 nm are trimethylaluminum (TMA), triethylaluminum (TEA), and triisobutylaluminum (TIBA). The substrate is either n-type Si(100) or SiO{sub 2} (quartz). The major aluminum-containing species detected are Al atoms and AlH and AlCH{sub 3} molecules. Their relative abundance is shown to depend on the absorbate molecule and the wavelength chosen. Marked differences are observed between the case of the Al-alkyls photolyzed under collision-free conditions in the gas phase and when these molecules are adsorbed to a substrate.

  4. Microstructure and texture developments in multiple pulses excimer laser crystallization of GaAs thin films

    International Nuclear Information System (INIS)

    In this paper, we observed and characterized changes in the microstructure and texture during recrystallization and grain growth in polycrystalline GaAs thin films using multiple pulses crystallization by a KrF excimer laser. Films of various thicknesses were studied to assess film thickness and laser energy density effects. In the low temperature domain corresponding to the partial melting regime, normal grain growth was observed. In the superlateral grain growth regime the increase in grain size was notable with grain sizes much greater than the film thickness. A bimodal grain size distribution emerged implying the onset of secondary grain growth. The change in grain size distribution, texture, and grain boundary texture were analyzed using scanning electron microscopy and electron backscatter diffraction. It was found that grain growth is accompanied by a strengthening in (001) texture, indicating that the grain growth phenomenon is strain energy driven. The experimental results are explained with theory of secondary grain growth in thin films.

  5. Time-resolved spectroscopy and fluorescence resonance energy transfer in the study of excimer laser damage of chromatin

    Science.gov (United States)

    Radu, L.; Mihailescu, I.; Radu, S.; Gazdaru, D.

    2007-09-01

    The analysis of chromatin damage produced by a 248 nm excimer laser radiation, for doses of 0.3-3 MJ/m 2 was carried out by time-resolved spectroscopy and fluorescence resonance energy transfer (FRET). The chromatin was extracted from a normal and a tumoral tissue of Wistar rats. The decrease with laser dose of the relative contribution of the excited state lifetimes of ethidium bromide (EtBr) bounded to chromatin constitutes an evidence of the reduction of chromatin deoxyribonucleic acid (DNA) double-strand structure. FRET was performed from dansyl chloride to acridine orange, both coupled to chromatin. The increase of the average distance between these ligands, under the action of laser radiation, reflects a loosening of the chromatin structure. The radiosensitivity of tumor tissue chromatin is higher than that of a normal tissue. The determination of the chromatin structure modification in an excimer laser field can be of interest in laser therapy.

  6. Eye-Tracker-Guided Non-Mechanical Excimer Laser Assisted Penetrating Keratoplasty

    Directory of Open Access Journals (Sweden)

    Achim Langenbucher

    2013-03-01

    Full Text Available Purpose: The purpose of the study was to implement a new eye tracking mask which could be used to guide the laser beam in automated non-mechanical excimer laser assisted penetrating keratoplasty. Materials and methods: A new trephination mask design with an elevated surface geometry has been proposed with a step formation between conical and flat interfaces. Two recipient masks of 7.5/8.0 mm have been manufactured and tested. The masks have outer diameter of 12.5 mm, step formation at 10.5 mm, and slope of conical surfaces 15°. Its functionality has been tested in different lateral positions and tilts on a planar surface, and pig eye experiments. After successful validation on porcine eyes, new masks have been produced and tested on two patients. Results: The build-in eye tracking software of the MEL 70 was always able to capture the masks. It has been shown that the unwanted pigmentation/pattern induced by the laser pulses on the mask surface does not influence the eye-tracking efficiency. The masks could be tracked within the 18 × 14 mm lateral displacement and up to 12° tilt. Two patient cases are demonstrated. No complications were observed during the surgery, although it needs some attention for aligning the mask horizontally before trephination. Stability of eye tracking masks is emphasized by inducing on purpose movements of the patient head. Conclusion: Eye-tracking-guided penetrating keratoplasty was successfully applied in clinical practice, which enables robust tracking criteria within an extended range. It facilitates the automated trephination procedure of excimer laser-assisted penetrating keratoplasty.

  7. Influence of electrode materials and surface roughness on the homogeneity of discharges in fluorine-based excimer laser gas mixtures

    NARCIS (Netherlands)

    Mathew, D.; Bastiaens, H.M.J.; Boller, K.-J.; Peters, P.J.M.; Schuöcker, Dieter

    2007-01-01

    The influence of electrode materials and surface roughness on the discharge homogeneity of F2 based excimer laser gas mixtures is investigated in a small x-ray preionised discharge chamber. The temporal and spatial evolution of the discharge is monitored by taking photographs of the discharge lumino

  8. Influence of thermal effects on the dynamic stability of the lasing wavelength of excimer-pumped dye lasers

    Energy Technology Data Exchange (ETDEWEB)

    Berik, E.; Davydenko, V. (Institut Fiziki, Tartu (Estonian SSR))

    1990-01-01

    The effect of a dynamic shift in lasing wavelength of a dye laser with transverse excimer pumping, which occurs due to thermal distortions of the active medium is investigated. The distortions cause the appearance of a refraction-index gradient. The occurrence of this effect is ascribed in part to a large Stokes shift in generation. 9 refs.

  9. Pure, single crystal Ge nanodots formed using a sandwich structure via pulsed UV excimer laser annealing

    Science.gov (United States)

    Liao, Ting-Wei; Chen, Hung-Ming; Shen, Kuan-Yuan; Kuan, Chieh-Hsiung

    2015-04-01

    In this paper, a sandwich structure comprising a SiO2 capping layer, amorphous Germanium (a-Ge) nanodots (NDs), and a pit-patterned Silicon (Si) substrate is developed, which is then annealed by utilizing a pulsed ultraviolet excimer laser in order to fabricate an array of pure, single crystal Ge NDs at room temperature. A wide bandgap SiO2 capping layer is used as a transparent thermally isolated layer to prevent thermal loss and Si-Ge intermixing. The two-dimensional pit-patterned Si substrate is designed to confine the absorbed laser energy, reduce the melting point, and block the surface migration of the Ge. After optimizing the laser radiation parameters such that the laser energy density is 200 mJ cm-2, the laser annealing period is 10 s, and the number of laser shots is 10, pure, single crystal Ge NDs that have both a regular arrangement and a uniform size distribution are obtained in the pits of the Si substrates. The Raman spectrum shows a highly symmetric Ge transversal optical peak with a full width at half maximum of 4.2 cm-1 at 300.7 cm-1, which is close to that of the original Ge wafer. In addition, the high-resolution transmission electron microscopy image for the Ge NDs and the corresponding selected area electron diffraction pattern shows a clear single crystalline structure without any impurities.

  10. Pure, single crystal Ge nanodots formed using a sandwich structure via pulsed UV excimer laser annealing.

    Science.gov (United States)

    Liao, Ting-Wei; Chen, Hung-Ming; Shen, Kuan-Yuan; Kuan, Chieh-Hsiung

    2015-04-24

    In this paper, a sandwich structure comprising a SiO2 capping layer, amorphous Germanium (a-Ge) nanodots (NDs), and a pit-patterned Silicon (Si) substrate is developed, which is then annealed by utilizing a pulsed ultraviolet excimer laser in order to fabricate an array of pure, single crystal Ge NDs at room temperature. A wide bandgap SiO2 capping layer is used as a transparent thermally isolated layer to prevent thermal loss and Si-Ge intermixing. The two-dimensional pit-patterned Si substrate is designed to confine the absorbed laser energy, reduce the melting point, and block the surface migration of the Ge. After optimizing the laser radiation parameters such that the laser energy density is 200 mJ cm(-2), the laser annealing period is 10 s, and the number of laser shots is 10, pure, single crystal Ge NDs that have both a regular arrangement and a uniform size distribution are obtained in the pits of the Si substrates. The Raman spectrum shows a highly symmetric Ge transversal optical peak with a full width at half maximum of 4.2 cm(-1) at 300.7 cm(-1), which is close to that of the original Ge wafer. In addition, the high-resolution transmission electron microscopy image for the Ge NDs and the corresponding selected area electron diffraction pattern shows a clear single crystalline structure without any impurities. PMID:25815515

  11. Design and performance characteristics of a krypton chloride ( = 222 nm) excimer laser

    Indian Academy of Sciences (India)

    N S Benerji; N Varshnay; A Singh; Bijendra Singh

    2014-01-01

    Development of a discharge-pumped krypton chloride (KrCl) laser operating at 222 nm wavelength is demonstrated. In this paper the design, successful realization and operating characteristics of KrCl excimer laser are reported. The laser is driven by a simple and efficient excitation technique using automatic UV pre-ionization with discharge-pumped self-sustained capacitor– capacitor (C–C) energy transfer circuit. The experimental investigations including output laser energy, temporal pulse parameters, emission spectra and beam profile of the KrCl laser were recorded. For high repetition rate operation, in-built, compact gas circulation system using tangential blower was incorporated. The laser was operated at 25 kV discharge voltage, gas mixture of 5 mbar HCl, 160 mbar kypton and neon as balance with a total gas pressure of ∼2.5 bar. These experiments produced an efficient and reliable output energy of 25 mJ from an active volume of 60 cm3.

  12. Fabrication of the Long Bragg Grating by Excimer Laser Micro Machining with High-Precision Positioning XXY Platform

    Directory of Open Access Journals (Sweden)

    Jian-Zhong Wu

    2014-03-01

    Full Text Available With the advancement of technology, the application of fiber Bragg grating is widely used as a Bragg grating sensor. Fiber Bragg grating is fabrication using excimer laser machining with the phase masker. The grating length is decided by the width of laser beam. In this paper, we proposed fabrication of the long Bragg grating by excimer Laser micro machining with a high-precision positioning XXY platform. The high-precision positioning XXY platform plays an important role for long FBG. It needs seriously to combine three short FBGs. Therefore, we can obtain a long FBG with 15mm length. This method can provide a solution to fabricate long FBG by using cheap laser with high-precision positioning XXY platform.

  13. Excimer laser crystallization of amorphous silicon carbide produced by ion implantation

    International Nuclear Information System (INIS)

    4H-SiC was implanted with 100-250 keV Ge+ and Xe+ ions and doses of 1x1014 to 1x1016 cm-2 at room temperature in order to produce 40-200 nm thick amorphous surface layers. The samples were irradiated with 1-50,000 pulses of a KrF excimer laser (248 nm wavelength, 30 ns pulse duration) using fluences of 150-900 mJ/cm2 to investigate the crystallization process as a function of the laser parameters. Crystallization as well as redistribution of the impurity atoms were analyzed by Rutherford backscattering spectrometry and infrared reflection measurements. Phase transitions occurring during the irradiation were studied by means of time-resolved reflectivity measurements. In order to explain the observed phase transitions numerical analysis was performed by solving the inhomogeneous heat flow equation using the parameters of the corresponding phases. In this work, we give a consistent description of the experimental results by the numerical simulations for the given laser setup. Depending on the amorphous layer thickness, melting, solidification, and crystallization of the amorphous phase can be effectively controlled by both the laser fluence and the number of laser pulses

  14. Comparison of Wavelight Allegretto Eye-Q and Schwind Amaris 750S excimer laser in treatment of high astigmatism

    OpenAIRE

    Bohac, Maja; Biscevic, Alma; Koncarevic, Mateja; Anticic, Marija; Gabric, Nikica; Patel, Sudi

    2014-01-01

    Purpose To compare functional outcomes of Wavelight Allegretto Eye-Q 400Hz and Schwind Amaris 750S excimer laser for astigmatism between 2 and 7 diopters(D). Methods Prospective comparative non-randomized case series of 480 eyes assigned in two laser groups and further divided into myopic and mixed astigmatism subgroups. All treatments were centered on corneal vertex. One-year results were compared between the groups. Statistical analysis was performed using z-test. Results Both Allegretto an...

  15. Synthesis and laser annealing of embedded CdSe-nanoparticles in SiO2 by pulsed excimer laser radiation

    International Nuclear Information System (INIS)

    CdSe-semiconductor nanocrystals embedded in SiO2 on silicon have been synthesized by ion implantation of Cd+ and Se+ followed by pulsed excimer laser annealing at room temperature. Transmission electron microscopy and x-ray diffraction-analysis results suggest that wurzite-type embedded CdSe nanocrystals have been formed. Since laser annealing can be applied locally this opens a route towards spatially selective annealing. In a second type of experiment pulsed laser annealing was performed on embedded CdSe nanoparticles synthesized by standard thermal annealing resulting in oriented ellipsoidal deformation and morphological changes of the larger precipitates. Computer simulation results suggest a size-selective temperature increase of the CdSe nanocrystals as the underlying mechanism

  16. The effect of 193 nm excimer laser radiation on the human corneal endothelial cell density

    International Nuclear Information System (INIS)

    The effect of 193 nm excimer laser radiation on human corneal endothelial cell density was examined. Fifty-five eyes from 35 patients underwent photorefractive keratectomy for myopia. Photomicrographs of the endothelium were taken a short time before the operation and on an average of 7 months postoperatively with a specular microscope. The average endothelial cell densities were preoperatively 3375 ± 266 cells/mm2 (means ± SD) and postoperatively 3348 ± 287 cells/mm2, corresponding to a fall of 27 cells/mm2 (N = 55). This fall in endothelial cell density was not statistically significant. A significant correlation between the change in cell density and age of the patient was found, with older patients losing more cells (N = 35, 2p < 0.05). The magnification of the specular microscope was found to change with corneal thickness. The importance of correcting the endothelial cell densities for corneal thickness is discussed. (au) 14 refs

  17. Diffraction and shaping analysis of excimer laser through an ultrasonic grating

    Science.gov (United States)

    Liu, Lixia; Zhou, Jinyun; Deng, Yafei; Liu, Haiyong; Lei, Liang; Wang, Bo

    2014-06-01

    A novel numerical simulation method for the shaping of an excimer laser beam by an acoustic grating is proposed. Partially coherent theory and extended Huygens-Fresnel principle are used to analyze the light intensity diffraction pattern. Fast Fourier transform function FFT in the Matlab is used to calculate the numerical integral, which makes the integral operation simple and efficient. It is shown by a numerical simulation that the output intensity distribution is closely related to the coherence width, Raman-Nath comprehensive parameter, diffraction distance and ultrasonic wave frequency. The simulation results show that a flat top beam can be obtained by controlling these parameters. On the other hand, the results are used as an effective analytic tool for the determination of the design parameters of acousto-optic modulator.

  18. The effect of 193 nm excimer laser radiation on the human corneal endothelial cell density

    Energy Technology Data Exchange (ETDEWEB)

    Isager, P.; Hjortdal, J.Oe.; Ehlers, N. [Aarhus Univ. Hospital, Dept. of Ophthalmology, Aarhus (Denmark)

    1996-06-01

    The effect of 193 nm excimer laser radiation on human corneal endothelial cell density was examined. Fifty-five eyes from 35 patients underwent photorefractive keratectomy for myopia. Photomicrographs of the endothelium were taken a short time before the operation and on an average of 7 months postoperatively with a specular microscope. The average endothelial cell densities were preoperatively 3375 {+-} 266 cells/mm{sup 2} (means {+-} SD) and postoperatively 3348 {+-} 287 cells/mm{sup 2}, corresponding to a fall of 27 cells/mm{sup 2} (N = 55). This fall in endothelial cell density was not statistically significant. A significant correlation between the change in cell density and age of the patient was found, with older patients losing more cells (N = 35, 2p < 0.05). The magnification of the specular microscope was found to change with corneal thickness. The importance of correcting the endothelial cell densities for corneal thickness is discussed. (au) 14 refs.

  19. Microlens Array Fabricated by Excimer Laser Micromachining with Gray-tone Photolithography

    Science.gov (United States)

    Tien, Chung-Hao; Chien, Yeh-En; Chiu, Yi; Shieh, Han-Ping D.

    2003-03-01

    We demonstrate the fabrication of a refractive microlens array by using 248 nm excimer laser micromachining with coded gray-tone mask photolithography. With pre-corrections to the nonlinear exposure process, the maximum deviation from the designed shape was below 5%. The fabricated hemispherical lens of 30 μm radius was used as a solid immersion lens (SIL) and combined with a 0.54 numerical aperture (NA) objective to achieve a 0.87 effective NA through the knife-edge scanning test. The experimental results agreed with those of the simulation. Unlike the methods such as the thermal melting process, this one-step optical exposure method with a coded mask provides a relatively fast and cost-effective way to realize a microlens array in optical data storage, information processing, and optical interconnection applications.

  20. Factors affecting the outcome of excimer laser photorefractive keratectomy: a preliminary multivariable regression analysis

    Science.gov (United States)

    Maguen, Ezra I.; Papaioannou, Thanassis; Nesburn, Anthony B.; Salz, James J.; Warren, Cathy; Grundfest, Warren S.

    1996-05-01

    Multivariable regression analysis was used to evaluate the combined effects of some preoperative and operative variables on the change of refraction following excimer laser photorefractive keratectomy for myopia (PRK). This analysis was performed on 152 eyes (at 6 months postoperatively) and 156 eyes (at 12 months postoperatively). The following variables were considered: intended refractive correction, patient age, treatment zone, central corneal thickness, average corneal curvature, and intraocular pressure. At 6 months after surgery, the cumulative R2 was 0.43 with 0.38 attributed to the intended correction and 0.06 attributed to the preoperative corneal curvature. At 12 months, the cumulative R2 was 0.37 where 0.33 was attributed to the intended correction, 0.02 to the preoperative corneal curvature, and 0.01 to both preoperative corneal thickness and to the patient age. Further model augmentation is necessary to account for the remaining variability and the behavior of the residuals.

  1. [Analysis of images in the prophylaxis and treatment of complications after kerato-refractive excimer laser surgeries].

    Science.gov (United States)

    Makarov, I A

    2003-01-01

    A total of 236 eyes of patients with myopia and hypermetropia of different severity degrees after photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) were observed. The densitometry and planimetry analysis of corneal images, obtained through storing them in the computer memory, was used to evaluate postoperatively the corneal condition. Planimetry was used to forecast the time of epithelization and to assess the efficiency of drug therapy. The optic density was found to increase, after excimer-laser surgeries, in all patients and it depended on a type of refraction and its degree. The optic-density dynamics of corneal images also depended on a degree and type of refraction as well as on a type of drug therapy. Hence, densitometry and planimetry, as objective methods used to follow up the patients after keratorefractive excimer-laser surgeries, make it possible to diagnose early enough the presence of complications related with disorders in transparency and healing of the cornea. PMID:12698885

  2. Report on the Study of Radiation Damage in Calcium Fluoride and Magnesium Fluoride Crystals for use in Excimer Laser Applications

    Energy Technology Data Exchange (ETDEWEB)

    None, None

    1999-10-04

    A study was performed to investigate the effects of radiation damage in calcium fluoride and magnesium fluoride crystals caused by gamma rays and UV photons from excimer lasers. The purpose was to study and correlate the damage caused by these two different mechanisms in various types of material used for fabricating optical elements in high power excimer lasers and lens systems of lithography tools. These optical systems are easily damaged by the laser itself, and it is necessary to use only the most radiation resistant materials for certain key elements. It was found that a clear correlation exists between the, radiation induced damage caused by high energy gamma rays and that produced by UV photons from the excimer laser. This correlation allows a simple procedure to be developed to select the most radiation resistant material at the ingot level, which would be later used to fabricate various components of the optical system. This avoids incurring the additional cost of fabricating actual optical elements with material that would later be damaged under prolonged use. The result of this screening procedure can result in a considerable savings in the overall cost of the lens and laser system.

  3. Photorefractive keratectomy for moderate myopia with the VISX and Summit excimer lasers: a retrospective study Ceratectomia fotorrefrativa para correção de miopia moderada com excimer lasers VISX e Summit: estudo retrospectivo

    Directory of Open Access Journals (Sweden)

    João C. Ribeiro

    2000-06-01

    Full Text Available Purpose: To present photorefractive keratectomy (PRK results for myopia ranging from -4,00 to - 6,00 diopters performed with the VISX and Summit excimer lasers. Methods: To be eligible for this study, patients had to be 20 to 45 years of age, have -4.00 to -6.00 diopters of myopia and have no more than 1 D of astigmatism. The Summit group was composed of 51 eyes. The baseline preoperative spherical equivalent of myopia was -5.22 ± 0.17 and surgeries were performed with the Excimed UV 200 LA Excimer Laser. In the VISX group, there were 53 eyes and the baseline refractive error was -4.85 ± 0.16 and surgeries were performed with the Twenty/Twenty Excimer Laser. Results: At six-month examination, haze ranged from 0 to 1 (M:0.56 ± 0.07 in the VISX group and from 0 to 3 (M:0.58 ± 0.08 in the Summit group. Uncorrected vision at six months was 20/20 or better in 22% of eyes and 20/40 or better in 83% of eyes in the VISX group. In the Summit group, 25% of eyes were 20/20 or better and 71% were 20/40 or better at the six-month examination. Conclusion: It is reassuring that PRK of patients with -4.00 to -6.00 D of myopia results in acceptable results.Objetivo: Apresentar os resultados obtidos com ceratecto-mia fotorrefrativa (PRK para a correção de miopia variando de -4,0 a -6,0 dioptrias realizadas com os excimer lasers VISX e Summit. Métodos: Para o estudo foram avaliados os resultados de PRK realizadas em pacientes com idade entre 20 e 45 anos, miopia entre -4,0 e -6,0 dioptrias e astigmatismo até 1,0 dioptria. O grupo operado com o laser da marca Summit era composto de 51 olhos. O equivalente esférico médio pré-operatório era de -5,22 ± 0,17 dioptrias e as cirurgias foram realizadas com o Excimed UV 200 LA Excimer Laser. O grupo operado com o laser VISX, era composto de 53 olhos e o erro refrativo preoperatório era de -4,85 ± 0,16 diop-trias e as cirurgias foram realizadas com o Twenty/Twenty Excimer Laser. Resultados: Exame seis meses

  4. UV excimer laser and low temperature plasma treatments of polyamide materials

    Science.gov (United States)

    Yip, Yiu Wan Joanne

    Polyamides have found widespread application in various industrial sectors, for example, they are used in apparel, home furnishings and similar uses. However, the requirements for high quality performance products are continually increasing and these promote a variety of surface treatments for polymer modification. UV excimer laser and low temperature plasma treatments are ideally suited for polyamide modification because they can change the physical and chemical properties of the material without affecting its bulk features. This project aimed to study the modification of polyamides by UV excimer laser irradiation and low temperature plasma treatment. The morphological changes in the resulting samples were analysed by scanning electron microscopy (SEM) and tapping mode atomic force microscopy (TM-AFM). The chemical modifications were studied by x-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS) and chemical force microscopy (CFM). Change in degree of crystallinity was examined by differential scanning calorimetry (DSC). After high-fluence laser irradiation, topographical results showed that ripples of micrometer size form on the fibre surface. By contrast, sub-micrometer size structures form on the polyamide surface when the applied laser energy is well below its ablation threshold. After high-fluence laser irradiation, chemical studies showed that the surface oxygen content of polyamide is reduced. A reverse result is obtained with low-fluence treatment. The DSC result showed no significant change in degree of crystallinity in either high-fluence or low-fluence treated samples. The same modifications in polyamide surfaces were studied after low temperature plasma treatment with oxygen, argon or tetrafluoromethane gas. The most significant result was that the surface oxygen content of polyamide increased after oxygen and argon plasma treatments. Both treatments induced many hydroxyl (-OH) and carboxylic acid (-COOH

  5. Krypton Gas for High Quality Single Wall Carbon Nanotubes Synthesis by KrF Excimer Laser Ablation

    Directory of Open Access Journals (Sweden)

    Jasim Al-Zanganawee

    2015-01-01

    Full Text Available We report for the first time the production of single wall carbon nanotubes (SWCNTs by KrF excimer laser ablation method under the krypton gas atmosphere. For the ablation experiment 450 mJ energy and 30 Hz repetition rate KrF excimer laser was used, and the target was prepared with the following composition: 0.6% Ni, 0.6% Co, and 98.8% C (atomic percentage. The ablation product was characterized by confocal Raman microspectroscopy, transmission electron microscopy (TEM, scanning electron microscopy (SEM, and thermogravimetric analysis (TGA. The SWCNTs obtained are a mixture of semiconducting and metallic types with narrow diameters distribution of 1.26 to 1.49 nm, are micrometers long, and contain low amount of graphite and amorphous carbon.

  6. Outcomes of excimer laser enhancements in pseudophakic patients with multifocal intraocular lens

    Directory of Open Access Journals (Sweden)

    Schallhorn SC

    2016-04-01

    Full Text Available Steven C Schallhorn,1–3 Jan A Venter,2 David Teenan,2 Julie M Schallhorn,3 Keith A Hettinger,2 Stephen J Hannan,2 Martina Pelouskova2 1Department of Ophthalmology, University of California, San Francisco, CA, USA; 2Optical Express, Glasgow, UK; 3Department of Ophthalmology, University of Southern California, Los Angeles, CA, USA Purpose: The aim of this study was to assess visual and refractive outcomes of laser vision correction (LVC to correct residual refraction after multifocal intraocular lens (IOL implantation. Patients and methods: In this retrospective study, 782 eyes that underwent LVC to correct unintended ametropia after multifocal IOL implantation were evaluated. Of all multifocal lenses implanted during primary procedure, 98.7% were refractive and 1.3% had a diffractive design. All eyes were treated with VISX STAR S4 IR excimer laser using a convectional ablation profile. Refractive outcomes, visual acuities, patient satisfaction, and quality of life were evaluated at the last available visit. Results: The mean time between enhancement and last visit was 6.3±4.4 months. Manifest spherical equivalent changed from -0.02±0.83 D (-3.38 D to +2.25 D pre-enhancement to 0.00±0.34 D (-1.38 D to +1.25 D post-enhancement. At the last follow-up, the percentage of eyes within 0.50 D and 1.00 D of emmetropia was 90.4% and 99.5%, respectively. Of all eyes, 74.9% achieved monocular uncorrected distance visual acuity 20/20 or better. The mean corrected distance visual acuity remained the same before (-0.04±0.06 logMAR [logarithm of the minimum angle of resolution] and after LVC procedure (-0.04±0.07 logMAR; P=0.70. There was a slight improvement in visual phenomena (starburst, halo, glare, ghosting/double vision following the enhancement. No sight-threatening complications related to LVC occurred in this study. Conclusion: LVC in pseudophakic patients with multifocal IOL was safe, effective, and predictable in a large cohort of

  7. Time resolved vacuum ultraviolet observations of excimer laser-produced YBa2Cu3O7 plasmas

    International Nuclear Information System (INIS)

    Simultaneous temporal and spatial resolution of the monochromatic vacuum ultraviolet emission from an excimer laser ablated YBa2Cu3O7 plasma has yielded quantitative information on the plasma generation and velocity. From the time resolved spectral data, plasma velocities were measured and found to be ∼2.3 x 106 cm/s. It was observed that vacuum ultraviolet emission from above the YBa2Cu3O7 surface does not occur until ∼20 ns after the beginning of the laser pulse. Energetic material continues to be ejected from the target for more than 100 ns after the end of the laser pulse

  8. Laser-SNMS-Analysen an Aerosol-Partikeln mit Hilfe eines neu implementierten VUV-Excimer-Lasersystems zur Einphotonenionisierung

    OpenAIRE

    Dambach, S

    2009-01-01

    Im Rahmen dieser Arbeit wurde für Laser-SNMS-Analysen ein VUV-Excimer-Lasersystem an ein bestehendes Flugzeitmassenspektrometer implementiert. Mit der nun für den nicht-resonanten Nachionisierungsprozess zur Verfügung stehenden Photonenenergie von 7,9 eV lassen sich 2/3 der Elemente des Periodensystems im Einphotonenprozess ionisieren. Die Analysen an Modellsystemen polyzyklischer aromatischer Kohlenwasserstoffe (PAK) führten aufgrund der Einphotonenionisierung zu deutlich...

  9. CAD/CAM interface design of excimer laser micro-processing system

    Science.gov (United States)

    Jing, Liang; Chen, Tao; Zuo, Tiechuan

    2005-12-01

    Recently CAD/CAM technology has been gradually used in the field of laser processing. The excimer laser micro-processing system just identified G instruction before CAD/CAM interface was designed. However the course of designing a part with G instruction for users is too hard. The efficiency is low and probability of making errors is high. By secondary development technology of AutoCAD with Visual Basic, an application was developed to pick-up each entity's information in graph and convert them to each entity's processing parameters. Also an additional function was added into former controlling software to identify these processing parameters of each entity and realize continue processing of graphic. Based on the above CAD/CAM interface, Users can design a part in AutoCAD instead of using G instruction. The period of designing a part is sharply shortened. This new way of design greatly guarantees the processing parameters of the part is right and exclusive. The processing of complex novel bio-chip has been realized by this new function.

  10. Long term Monitoring of tropospheric ozone with excimer laser based DIAL system

    International Nuclear Information System (INIS)

    The description of automatic DIAL system for the long-term monitoring of ozone density in 0.5 km - 12 km altitude range is presented. The lidar is based on XeCl and KrF excimer lasers. The radiation of KrF laser is converted in hydrogen and deuterium Raman cells to obtain 277 nm and 292 nm wavelengths. The radiation backscattered from atmosphere is collected by a 60-cm-aperture Cassegraine telescope. Optical signals are detected by the PMTs operated in analog moge and digitized by 12 bit 30 MHz ADCs. The low altitude range (0.5 km-2 km) is covered by an additional 30-cm-aperture Newtonian telescope. Ozone density is calculated from the standard DIAL expressions with correction for differential backscattering and extinction. The system is operated in automatic mode and the duration of sounding session is determined only by weather conditions. The results of long-term sessions are presented as 3-D or color maps. The additional information about ozone fluxes is obtained from the correlation analysis of lidar data

  11. UV-laser-induced nanoclusters in silver ion-exchanged soda-lime silicate glass

    International Nuclear Information System (INIS)

    Excimer-laser irradiation (ArF: 193 nm) was performed on silver-exchanged commercial soda-lime silicate glass. Silver nanoclusters were obtained with an average size dependent on the irradiation time, without subsequent heating. Laser irradiation induces the reduction of silver ions and promotes the silver atoms aggregation

  12. Y-Ba-Cu-O thick film preparation using multistep KrF excimer laser deposition

    International Nuclear Information System (INIS)

    Thick films of high-temperature superconductors (HTSC) have attracted much attention to a number of current-carrying applications such as current leads, interconnects, current limiters and cryotron-type switches. As the film thickness of HTSC films is increased using the conventional method of pulsed laser deposition, the surface morphology is degraded during the film deposition. This structural transition results in decreasing the critical current density with the film thickness. Here, a multistep deposition technique in the KrF excimer laser ablation is used to prepare Y-Ba-Cu-O thick films. The high-quality Y-Ba-Cu-O superconducting films of thickness of a few mm were formed by optimizing the processing conditions from the bottom to the surface of the film. The initial ultrathin layer of a few nm was prepared at the low repetition rate of 1 Hz at laser fluence 3 J cm-2. Then, various repetition rates at the fluence 2 J cm-2 were chosen for deposition of the intermediate layer and the surface layer, both with thicknesses of about 1 μm. It is shown that surface morphology and vertical growth are significantly dominated by the initial layer structure and the following deposition conditions. The thick films with high Tc(zero) 89 K were obtained when the surface layer was prepared at a lower repetition rate under lower process temperature. The three step procedure prepared the superconducting thick films with the critical current density of 1.2 x 106 A cm-2 (at 5 K). (orig.)

  13. Scanning electron microscopy and thermal characteristics of dentin ablated by a short-pulse XeCl excimer laser.

    Science.gov (United States)

    Neev, J; Stabholtz, A; Liaw, L H; Torabinejad, M; Fujishige, J T; Ho, P D; Berns, M W

    1993-01-01

    The interaction of a short pulse XeCl excimer laser radiation with human dentin was investigated. The dependence of surface temperatures and temperature gradients into the treated teeth on laser parameters such as fluence (0.5J/cm2-7J/cm2), pulse repetition rate (1Hz-35Hz), and spot size (0.004cm2-0.12cm2) was studied. Additionally, the effect of fluence and pulse repetition rate on dentin microstructure was studied using scanning electron microscopy (SEM). It is demonstrated that this "cold ablation" excimer laser can result in significant thermal modification in the dentin surfaces. Changes include the formation of melted dentin grains, which uniformly cover the surface and the exposed dentin tubules. Maximum temperatures of the ablated surfaces, however, remained relatively low at most laser parameters used. Also, the immediate neighborhood of the root canal was essentially undisturbed at most laser parameters. These observations suggest that with the appropriate choice of parameters XeCl lasers can be effective in producing surface structures that may prove useful in enhancing bond strength or other applications in dentistry, without exposing tooth pulp to significant temperature elevation. PMID:8515674

  14. An annealing method for switching AlGaN/GaN field effect transistors employing an excimer laser

    International Nuclear Information System (INIS)

    A post-annealing method employing excimer laser pulses is proposed to improve the transfer characteristics and the breakdown voltage of unpassivated AlGaN/GaN heterostructure field-effect transistors (HFETs) for switching devices. XeCl excimer laser pulses with a wavelength of 308 nm anneal the unpassivated AlGaN/GaN HFET after Schottky gate metallization. The interface defects between the Schottky gate metal and the GaN layer are decreased by the lateral heat diffusion of the laser pulses. The temperature of the device during the laser pulse is analysed by the one-dimensional heat diffusion equation. Our experimental results show that the drain current and the maximum transconductance of the AlGaN/GaN HFET after 10 laser pulses are 496 and 134 mS mm-1, while a virgin device shows 434 and 113 mS mm-1, respectively. The measured leakage current of the AlGaN/GaN HFET at VG=-6 V is decreased from 1.95 to 1.53 mA mm-1 after 600 laser pulses. The breakdown voltage of the AlGaN/GaN HFET is increased due to the decreased leakage current

  15. Development of a Silicon Based Electron Beam Transmission Window for Use in a KrF Excimer Laser System

    CERN Document Server

    Gentile, C A; Hartfield, J W; Hawryluk, R J; Hegeler, F; Heitzenroeder, P J; Jun, C H; Ku, L P; Lamarche, P H; Myers, M C; Parker, J J; Parsells, R F; Payen, M; Raftopoulos, S; Sethian, J D

    2002-01-01

    The Princeton Plasma Physics Laboratory (PPPL), in collaboration with the Naval Research Laboratory (NRL), is currently investigating various novel materials (single crystal silicon, , and ) for use as electron-beam transmission windows in a KrF excimer laser system. The primary function of the window is to isolate the active medium (excimer gas) from the excitation mechanism (field-emission diodes). Chosen window geometry must accommodate electron energy transfer greater than 80% (750 keV), while maintaining structural integrity during mechanical load (1.3 to 2.0 atm base pressure differential, approximate 0.5 atm cyclic pressure amplitude, 5 Hz repetition rate) and thermal load across the entire hibachi area (approximate 0.9 W centre dot cm superscript ''-2''). In addition, the window must be chemically resistant to attack by fluorine free-radicals (hydrofluoric acid, secondary). In accordance with these structural, functional, and operational parameters, a 22.4 mm square silicon prototype window, coated w...

  16. Effect of Homoharringtonine on Corneal Haze after Excimer Laser Photorefractive Keratectomy in Rabbits

    Institute of Scientific and Technical Information of China (English)

    ZHANG Mingchang; WANG Li; WANG Yong; DING Zhengping; MAI Caikeng; NIE Shaosong; CHEN Fei

    2005-01-01

    To evaluate the inhibiting effect of Homoharringtonine HHT) on the corneal haze after excimer laser photorefractive keratectomy (PRK) in rabbits. 18 healthy rabbits which underwent PRK were randomly divided into three groups (A, B and C). The refractive degree of ablation was -10. 0DS in each group. Group A was locally treated with a piece of filter paper soaked with 1 mg/mi HHT for 5 min, and then the entire cornea was repeatedly irrigated with balance solution;Group B was dropped with 0.1 mg/mL HHT after PRK for 3 months; Group C was the control group. Corneal haze, histopathology, response, ect. were investigated. The corneal haze was sig nificantly less in group A, while the difference between group B and group C was insignificant.Keratocytes and fibrocytes in corneal stroma were more active up to 3 months in group B and group C. Intraoperative use of topical HHT can reduce corneal haze after PRK in rabbits.

  17. Raman scattering measurements in flames using a tunable KrF excimer laser

    Science.gov (United States)

    Wehrmeyer, Joseph A.; Cheng, Tsarng-Sheng; Pitz, Robert W.

    1992-01-01

    A narrow-band tunable KrF excimer laser is used as a spontaneous vibrational Raman scattering source to demonstrate that single-pulse concentration and temperature measurements, with only minimal fluorescence interference, are possible for all major species (O2, N2, H2O, and H2) at all stoichiometries (fuel-lean to fuel rich) of H2-air flames. Photon-statistics-limited precisions in these instantaneous and spatially resolved single-pulse measurements are typically 5 percent, which are based on the relative standard deviations of single-pulse probability distributions. In addition to the single-pulse N2 Stokes/anti-Stokes ratio temperature measurement technique, a time-averaged temperature measurement technique is presented that matches the N2 Stokes Raman spectrum to theoretical spectra by using a single intermediate state frequency to account for near-resonance enhancement. Raman flame spectra in CH4-air flames are presented that have good signal-to-noise characteristics and show promise for single-pulse UV Raman measurements in hydrocarbon flames.

  18. Excimer Laser Phototherapeutic Keratectomy for the Treatment of Clinically Presumed Fungal Keratitis

    Directory of Open Access Journals (Sweden)

    Liang-Mao Li

    2014-01-01

    Full Text Available This retrospective study was to evaluate treatment outcomes of excimer laser phototherapeutic keratectomy (PTK for clinically presumed fungal keratitis. Forty-seven eyes of 47 consecutive patients underwent manual superficial debridement and PTK. All corneal lesions were located in the anterior stroma and were resistant to medication therapy for at least one week. Data were collected by a retrospective chart review with at least six months of follow-up data available. After PTK, infected corneal lesions were completely removed and the clinical symptoms resolved in 41 cases (87.2%. The mean ablation depth was 114.39±45.51 μm and diameter of ablation was 4.06±1.07 mm. The mean time for healing of the epithelial defect was 8.8±5.6 days. Thirty-four eyes (82.9% showed an improvement in best spectacle-corrected visual acuity of two or more lines. PTK complications included mild to moderate corneal haze, hyperopic shift, irregular astigmatism, and thinning cornea. Six eyes (12.8% still showed progressed infection, and conjunctival flap covering, amniotic membrane transplantation, or penetrating keratoplasty were given. PTK is a valuable therapeutic alternative for superficial infectious keratitis. It can effectively eradicate lesions, hasten reepithelialization, and restore and preserve useful visual function. However, the selection of surgery candidates should be conducted carefully.

  19. Post-growth annealing of germanium-tin alloys using pulsed excimer laser

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lanxiang; Wang, Wei; Zhou, Qian; Yeo, Yee-Chia, E-mail: yeo@ieee.org [Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117582 (Singapore); Pan, Jisheng; Zhang, Zheng [Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), Singapore 117602 (Singapore); Tok, Eng Soon [Department of Physics, National University of Singapore, Singapore 117551 (Singapore)

    2015-07-14

    We investigate the impact of pulsed excimer laser anneal on fully strained germanium-tin alloys (Ge{sub 1−x}Sn{sub x}) epitaxially grown on Ge substrate by molecular beam epitaxy. Using atomic force microscopy, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy, the morphological and compositional evolution of Ge{sub 1−x}Sn{sub x} with Sn content up to 17% after annealing using various conditions is studied. Ge{sub 0.83}Sn{sub 0.17} samples annealed at 80 mJ/cm{sup 2} or 150 mJ/cm{sup 2} have no observable changes with respect to the as-grown sample. However, Ge{sub 0.83}Sn{sub 0.17} samples annealed at 250 mJ/cm{sup 2} or 300 mJ/cm{sup 2} have Sn-rich islands on the surface, which is due to Sn segregation in the compressively strained epitaxial film. For Ge{sub 0.89}Sn{sub 0.11}, significant Sn redistribution occurs only when annealed at 300 mJ/cm{sup 2}, indicating that it has better thermal stability than Ge{sub 0.83}Sn{sub 0.17}. A mechanism is proposed to explain the formation of Sn-rich islands and Sn-depleted regions.

  20. Post-growth annealing of germanium-tin alloys using pulsed excimer laser

    International Nuclear Information System (INIS)

    We investigate the impact of pulsed excimer laser anneal on fully strained germanium-tin alloys (Ge1−xSnx) epitaxially grown on Ge substrate by molecular beam epitaxy. Using atomic force microscopy, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy, the morphological and compositional evolution of Ge1−xSnx with Sn content up to 17% after annealing using various conditions is studied. Ge0.83Sn0.17 samples annealed at 80 mJ/cm2 or 150 mJ/cm2 have no observable changes with respect to the as-grown sample. However, Ge0.83Sn0.17 samples annealed at 250 mJ/cm2 or 300 mJ/cm2 have Sn-rich islands on the surface, which is due to Sn segregation in the compressively strained epitaxial film. For Ge0.89Sn0.11, significant Sn redistribution occurs only when annealed at 300 mJ/cm2, indicating that it has better thermal stability than Ge0.83Sn0.17. A mechanism is proposed to explain the formation of Sn-rich islands and Sn-depleted regions

  1. Fabrication and formation mechanism of hollow MgO particles by pulsed excimer laser ablation of Mg in liquid

    International Nuclear Information System (INIS)

    We report on the formation of hollow MgO particles by excimer laser ablation of bulk Mg in water and aqueous solutions of sodium dodecyl sulfate (SDS) and sodium citrate (SC). Lamellar nanostructures of Mg(OH)2 also formed in water, but the formation could be avoided by the addition of SDS or SC. Laser ablation produced not only Mg species that were oxidized into MgO and Mg(OH)2 in water, but also cavitation bubbles. The bubble interfaces trapped the MgO nanoparticles to decrease the surface free energy of the system, finally resulting in hollow particles.

  2. Fabrication of self-organized conical microstructures by excimer laser irradiation of cyanoacrylate-carbon nanotube composites

    International Nuclear Information System (INIS)

    Self-organized conical microstructures are fabricated by 308 nm XeCl excimer laser irradiation of cyanoacrylate-carbon nanotube composites in air. The morphology of the surface on the composite films is studied, varying the total number and fluence of the applied laser pulses. A simple mechanism of the fabrication based on the evaporation of cyanoacrylate and the burning of carbon nanotubes is proposed. The conical peak structures of cyanoacrylate-carbon nanotube composite films show good field-emission properties. Similar structures are also observed on carbon nanotube arrays

  3. Fabrication of self-organized conical microstructures by excimer laser irradiation of cyanoacrylate-carbon nanotube composites

    Science.gov (United States)

    Liu, Yuming; Liu, Liang; Fan, Shoushan

    2005-02-01

    Self-organized conical microstructures are fabricated by 308 nm XeCl excimer laser irradiation of cyanoacrylate-carbon nanotube composites in air. The morphology of the surface on the composite films is studied, varying the total number and fluence of the applied laser pulses. A simple mechanism of the fabrication based on the evaporation of cyanoacrylate and the burning of carbon nanotubes is proposed. The conical peak structures of cyanoacrylate-carbon nanotube composite films show good field-emission properties. Similar structures are also observed on carbon nanotube arrays.

  4. Properties of the ablation process for excimer laser ablation of Y1Ba2Cu3O7

    International Nuclear Information System (INIS)

    The process of excimer laser ablation has been studied while varying the laser fluence from 0.237 to 19.1 J/cm2. Ion time-of-flight, total charge, target etch depth per pulse, and etch volume per pulse have been measured. Results indicate a maximum ablation volume and minimum ionization fraction occur near 5 J/cm2. Several of the parameters measured vary rapidly in the 1--5 J/cm2 range. Variation in these parameters strongly influences the properties of films grown by this technique

  5. Effect of phosphorus ion implantation on crystallization of amorphous silicon films under exposure to excimer laser radiation pulses

    International Nuclear Information System (INIS)

    The effect of implanted phosphorus ions on the crystallization of thin amorphous silicon films under the action of nanosecond radiation pulses of a XeCl excimer laser is studied. The amorphous silicon films with a thickness of 90 nm on glass substrates, were implanted with phosphorus ions at a dose of 3 x 1014 and 3 x 1015 cm-2. The subsequent laser treatments were performed using energies both above and below a threshold corresponding to the fusion of amorphous silicon. The structure of the silicon films was studied using Raman spectroscopy. The conclusion is made that implanted phosphorus stimulates nucleation, especially in the case of liquid phase crystallization

  6. Photodamage to calf lenses in vitro by excimer laser radiation at 308, 337, and 350 nm

    International Nuclear Information System (INIS)

    Calf lenses in vitro were irradiated using an excimer laser at wavelengths of 308, 337, and 350 nm for times ranging from 10 minutes to 5 hours. The laser power was 2.0 watts (W) at 308 nm, 0.2 W at 337 nm, and 2.0 W at 350 nm. During irradiations, the visible light transmission (632.8 nm) of the lenses was measured and found to be decreased markedly with 308- or 337-nm irradiation. No change in visible light transmission was observed with irradiation at 350 nm. Irradiated lenses were also compared with dark control lenses by photographic record. Lenses exposed to 308-nm ultraviolet (UV) radiation for 10-30 minutes showed significant yellow-brown pigmentation and colorless opacification compared with dark controls. Lenses exposed to 337-nm UV light showed primarily colorless opacity with little pigment production. Lenses exposed to 350-nm radiation for up to 1 hour were visibly indistinguishable from dark controls. After photolysis, the lenses were separated into water-soluble and insoluble fractions and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Compared with dark controls, UV-exposed lenses (308 or 337 nm) showed loss of 20-30-kilodalton (kD) material and production of higher molecular weight material at 40-60 kD and greater than 100 kD. There was no evidence of such changes after 350-nm exposure. The data gave the following order for the degree of photodamage: 308 nm approximately 5 x 337 nm greater than 20 x 350 nm. An action spectrum for lens damage is presented

  7. Excimer laser-assisted recanalisation of femoral arterial stenosis or occlusion caused by the use of Angio-Seal

    International Nuclear Information System (INIS)

    The aim of this study was to demonstrate the effect of excimer laser and balloon angioplasty of femoral artery stenosis and occlusion after use of a haemostatic puncture closure device. A haemostatic puncture closure device (Angio-Seal) was used in 6000 patients after diagnostic or therapeutic artery catheterisation. In 34 of those patients symptoms of peripheral artery disease occurred. Sixteen of those 34 cases were transferred to our clinic for excimer laser angioplasty. All 16 patients presented with symptoms of acute peripheral artery disease within 1-14 days: superficial femoral artery (SFA) occlusions (4 cases); superficial femoral artery stenosis (3 cases); high-grade stenosis of the common femoral artery (CFA; 3 cases); high-grade stenosis of CFA; SFA and profund femoral artery (PFA; 3 cases); and occlusions of CFA, SFA and PFA (3 cases). Before any procedure was performed, informed consent was given by the patient, which included the use of the Angio-Seal closure device. Every patient who had to undergo recanalisation procedures gave additional informed consent which especially included the usage of the excimer laser for recanalisation. A measurement of the walking distance, ankle-brachial systolic pressure index (ABI) and diagnostic angiography was performed in 13 cases before and immediate after as well as 3 and 6 months after therapeutic percutaneous transluminal laser angioplasty followed by balloon angioplasty (PTLA/PTA). In 3 patients the risks of PTLA/PTA was considered too high; those patients underwent surgical repair. Angiographic and clinical improvement was achieved in 13 of 13 patients. The mean walking distance increased from 81 to >400 m. The average ankle-brachial systolic pressure index (ABI) increased from 0.47 to 0.84. One patient developed a dissection of the SFA, and in 1 case a peripheral embolisation was seen. The PTLA/PTA technique is a successful therapeutic option for patients with femoral artery occlusion or high-grade stenosis

  8. Excimer laser assisted re-oxidation of BaTiO3 thin films on Ni metal foils

    International Nuclear Information System (INIS)

    Excimer laser assisted re-oxidation for reduced, crystallized BaTiO3 thin films on Ni-foils was investigated. It was found that the BaTiO3 can be re-oxidized at an oxygen partial pressure of ∼50 mTorr and substrate temperature of 350 °C without forming a NiOx interface layer between the film and base metal foil. The dielectric permittivity of re-oxidized films was >1000 with loss tangent values <2% at 100 Hz, 30 mVrms excitation signal. Electron Energy Loss Spectroscopy indicated that BaTiO3 thin films can be re-oxidized to an oxygen stoichiometry close to ∼3 (e.g., stoichiometric). High resolution cross sectional transmission electron microscopy showed no evidence of NiOx formation between the BaTiO3 and the Ni foil upon excimer laser re-oxidation. Spectroscopic ellipsometry studies on laser re-oxidized [001]C and [111]C BaTiO3 single crystals indicate that the re-oxidation of BaTiO3 single crystals is augmented by photo-excitation of the ozone, as well as laser pulse induced temperature and local stress gradients

  9. Excimer laser assisted re-oxidation of BaTiO3 thin films on Ni metal foils

    Science.gov (United States)

    Bharadwaja, S. S. N.; Rajashekhar, A.; Ko, S. W.; Qu, W.; Motyka, M.; Podraza, N.; Clark, T.; Randall, C. A.; Trolier-McKinstry, S.

    2016-01-01

    Excimer laser assisted re-oxidation for reduced, crystallized BaTiO3 thin films on Ni-foils was investigated. It was found that the BaTiO3 can be re-oxidized at an oxygen partial pressure of ˜50 mTorr and substrate temperature of 350 °C without forming a NiOx interface layer between the film and base metal foil. The dielectric permittivity of re-oxidized films was >1000 with loss tangent values oxygen stoichiometry close to ˜3 (e.g., stoichiometric). High resolution cross sectional transmission electron microscopy showed no evidence of NiOx formation between the BaTiO3 and the Ni foil upon excimer laser re-oxidation. Spectroscopic ellipsometry studies on laser re-oxidized [001]C and [111]C BaTiO3 single crystals indicate that the re-oxidation of BaTiO3 single crystals is augmented by photo-excitation of the ozone, as well as laser pulse induced temperature and local stress gradients.

  10. Analysis of damage threshold of K9 glass irradiated by 248-nm KrF excimer laser

    Science.gov (United States)

    Wang, Xi; Shao, Jingzhen; Li, Hua; Nie, Jinsong; Fang, Xiaodong

    2016-02-01

    The theoretical model of K9 glass irradiated by a 248-nm KrF excimer laser was established, and a numerical simulation was performed to calculate temperature and thermal stress fields in the K9 glass sample using the finite element method. The laser-induced damage thresholds were defined and calculated, and the effect of repetition frequency and the number of pulses on the damage threshold were also studied. Furthermore, the experiment research was carried out to confirm the numerical simulation. The damage threshold and damage morphology were analyzed by means of a metallurgical microscope and scanning electron microscopy. The simulation and experimental results indicated that the damage mechanism of K9 glass irradiated by a KrF excimer laser was melting damage and stress damage, and the stress damage first appeared inside the K9 glass sample. The tensile stress damage threshold, the compressive stress damage threshold, and the melting damage threshold were 0.64, 0.76, and 1.05 J/cm2, respectively. The damage threshold decreased with increasing repetition frequency and number of laser pulses. The experimental results indicated that the damage threshold of K9 glass was 2.8 J/cm2.

  11. Excimer laser assisted re-oxidation of BaTiO{sub 3} thin films on Ni metal foils

    Energy Technology Data Exchange (ETDEWEB)

    Bharadwaja, S. S. N., E-mail: s.s.n.bharadwaja@gmail.com; Ko, S. W.; Qu, W.; Clark, T. [Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Rajashekhar, A. [Materials Science and Engineering Department, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Motyka, M. [Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Podraza, N. [Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606 (United States); Wright Center for Photovoltaics Innovation and Commercialization, University of Toledo, Toledo, Ohio 43606 (United States); Randall, C. A.; Trolier-McKinstry, S. [Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Materials Science and Engineering Department, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

    2016-01-14

    Excimer laser assisted re-oxidation for reduced, crystallized BaTiO{sub 3} thin films on Ni-foils was investigated. It was found that the BaTiO{sub 3} can be re-oxidized at an oxygen partial pressure of ∼50 mTorr and substrate temperature of 350 °C without forming a NiO{sub x} interface layer between the film and base metal foil. The dielectric permittivity of re-oxidized films was >1000 with loss tangent values <2% at 100 Hz, 30 mV{sub rms} excitation signal. Electron Energy Loss Spectroscopy indicated that BaTiO{sub 3} thin films can be re-oxidized to an oxygen stoichiometry close to ∼3 (e.g., stoichiometric). High resolution cross sectional transmission electron microscopy showed no evidence of NiO{sub x} formation between the BaTiO{sub 3} and the Ni foil upon excimer laser re-oxidation. Spectroscopic ellipsometry studies on laser re-oxidized [001]{sub C} and [111]{sub C} BaTiO{sub 3} single crystals indicate that the re-oxidation of BaTiO{sub 3} single crystals is augmented by photo-excitation of the ozone, as well as laser pulse induced temperature and local stress gradients.

  12. Excimer laser micromachining of aspheric microlens arrays based on optimal contour mask design and laser dragging method.

    Science.gov (United States)

    Chiu, Chi-Cheng; Lee, Yung-Chun

    2012-03-12

    This paper presents an improved excimer laser micromachining method for fabricating arrayed microstructures with a predesigned surface profile. The proposed method is developed from a conventional biaxial laser dragging method, but numerical analysis and optimal pattern design on the contour mask are introduced so that the machined surface profiles can be well controlled and matched to the designed profiles. To demonstrate the capability of this new approach, an array of aspheric microlenses that have analog surfaces for minimizing the focal spot sizes of the lenses is designed and fabricated. An array of 10×10 microlenses with an aperture size of 100 μm and a designed aspheric profile are obtained experimentally. The machined surface profiles are closely matched to their designed ones, with a profile deviation of less than 1 μm. Furthermore, the machined surfaces are smooth, with an average surface roughness of around 2 nm. Optical measurements on these machined aspheric microlenses show minimized focal spot sizes approaching their optical diffraction limits. PMID:22418468

  13. Single application on iris localization technology in excimer laser for astigmatism

    Directory of Open Access Journals (Sweden)

    Jun-Hua Hao

    2014-06-01

    Full Text Available AIM:To discuss the single application on iris localization technology in excimer laser for the treatment of astigmatism. METHODS:Totally 203 cases(406 eyesof laser in situ keratomileusis(LASIKin the treatment of compound myopic astigmatism patients were operated from November 2011 to November 2012 in our hospital. They were divided into two groups. One was observation group using iris localization and the other was control group using routine operation. Patients in the observation group of 100 cases(200 eyes, aged 18-43 years old, spherical diopter was -1.25 to -8.75D, astigmatism was -1.0 to -3.25D. In control group, 103 patients(206 eyes, aged 19-44 years old, spherical diopter was -1.75-9.50D, astigmatism was -1.0 to -3.25D. The patients in the observation group before the application of WaveScan aberrometer check for iris image, spherical lens, cylindrical lens and astigmatism axis data operation, only single application of iris location, without using wavefront aberration guided technology, laser cutting patterns for conventional LASIK model, spherical, cylindrical mirror and astigmatism axis data source to preoperative wavefront aberration results. The control group received routine LASIK. It was applicated comprehensive optometry optometry respectively to examine astigmatism and axial, based on the computer analysis during the preoperative, 1wk after the operation, and 6mo. Analysis of using SPSS 17 statistical software, it was independent-sample t test between the two groups of residual astigmatism and astigmatism axis. RESULTS:Postoperative residual astigmatism, the observation group was significantly better than the control group. Astigmatism axial measurement after operation, the observation group was significantly less than that of the control group. Postoperative visual acuity at 6mo, the observation group was better than that of the control group. The difference was statistically significant. CONCLUSION: For patients who cannot

  14. Excimer laser micropatterning of freestanding thermo-responsive hydrogel layers for cells-on-chip applications

    International Nuclear Information System (INIS)

    We report a novel reliable and repeatable technologic manufacturing protocol for the realization of micro-patterned freestanding hydrogel layers based on thermo-responsive poly-(N-isopropyl)acrylamide (PNIPAAm), which have potential to be employed as temperature-triggered smart surfaces for cells-on-chip applications. PNIPAAm-based films with controlled mechanical properties and different thicknesses (100–300 µm thickness) were prepared by injection compression moulding at room temperature. A 9 × 9 array of 20 µm diameter through-holes is machined by means of the KrF excimer laser on dry PNIPAAm films which are physically attached to flat polyvinyl chloride (PVC) substrates. Machining parameters, such as fluence and number of shots, are optimized in order to achieve highly resolved features. Micro-structured freestanding films are then easily obtained after hydrogels are detached from PVC by gradually promoting the film swelling in ethanol. In the PNIPAAm water-swollen state, the machined holes’ diameter approaches a slight larger value (30 µm) according to the measured hydrogel swelling ratio. Thermo-responsive behaviour and through-hole tapering characterization are carried out by metrology measurements using an optical inverted and confocal microscope setup, respectively. After the temperature of freestanding films is raised above 32 °C, we observe that the shrinkage of the whole through-hole array occurs, thus reducing the holes’ diameter to less than a half its original size (about 15 µm) as a consequence of the film dehydration. Different holes’ diameters (10 and 30 µm) are also obtained on dry hydrogel employing suitable projection masks, showing similar shrinking behaviour when hydrated and undergone thermo-response tests. Thermo-responsive PNIPAAm-based freestanding layers could then be integrated with other suitable micro-fabricated thermoplastic components in order to preliminary test their feasibility in operating as temperature

  15. X-Ray Photoelectron Spectroscopy study for far UV-Excimer laser (λ = 193nm) surface modifications of polyethylene terephtalate

    International Nuclear Information System (INIS)

    We have studied by X-Ray Photoelectron Spectroscopy (XPS), the surface of Polyethylene Terephtalate treated by pulsed far Ultra Violet (UV) radiation delivered by an Excimer laser (λ = 193nm). Treatments were carried out under different gaseous atmospheres to discriminate the mechanisms leading to the modifications of the polymer surface. In particular, a pronounced deoxidation due to the loss of CO and CO2 is observed below the ablation threshold. Furthermore, treatments under oxygen and nitrogen atmospheres reveal the opportunity of grafting new functionalities at the polymer surfaces. (author). 13 refs, 4 figs, 3 tabs

  16. Synthesis and properties of Ag/ZnO core/shell nanostructures prepared by excimer laser ablation in liquid

    OpenAIRE

    Yan Zhao; Shuanghao Li; Yong Zeng; Yijian Jiang

    2015-01-01

    Ag/ZnO core/shell nanostructure was synthesised by a 248-nm KrF excimer pulsed laser ablation in a liquid solution for the first time. It was found that the surface plasma resonance absorption of the Ag/ZnO core/shell nanostructures can be tuned by the thickness of the ZnO shell, which is in agreement with the finite difference in the time domain simulation. Furthermore, the ultraviolet emission spectrum of the Ag/ZnO core/shell nanostructures was stronger and blue-shifted compared with that ...

  17. Chapter 33: Excimer Laser Preparation of SnO(2) and SnO(2)/TiO(2) Nanoparticles

    Czech Academy of Sciences Publication Activity Database

    Fajgar, Radek; Kupčík, Jaroslav; Šubrt, Jan; Dřínek, Vladislav

    Dordrecht: Springer Science, 2011 - (Reithmaier, J.; Paunovic, P.; Kulisch, W.; Popov, C.), s. 305-314. (NATO Science for Peace and Security Series - B:. Physics and Biophysics). ISBN 978-94-007-0902-7. ISSN 1871-465X. [NATO-Advanced-Study-Institute Conference on Nanotechnological Basis for Advanced Sensors. Sozopol (BG), 30.05.2010-11.06.2010] Institutional research plan: CEZ:AV0Z40720504; CEZ:AV0Z40320502 Keywords : tin oxides * titanium dioxide * excimer laser Subject RIV: CF - Physical ; Theoretical Chemistry

  18. Influence of laser beam’s image-plane position on geometry of through-holes in percussion-drilled glass using excimer laser

    OpenAIRE

    Ales Babnik

    2013-01-01

    We study the influence of a laser beam’s image-plane position relative to the processed surface for the deep-hole, laser-microdrilling of soda-lime glass with an excimer 308-nm laser and mask-projection technique. It is demonstrated that the image-plane position has a significant influence on the hole’s tapering and final depth. Holes with exit diameters up to 10 times smaller than the mask-image diameter are produced in the case of perforation during the appropriate process phase determined ...

  19. Influence of laser beam's image-plane position on geometry of through-holes in percussion-drilled glass using excimer laser

    OpenAIRE

    Petkovšek, Rok; Babnik, Aleš; Možina, Janez

    2015-01-01

    We study the influence of a laser beam's image-plane position relative to the processed surface for the deep-hole, laser-microdrilling of soda-lime glass with an excimer 308-nm laser and mask-projection technique. It is demonstrated that the image-plane position has a significant influence on the holes tapering and final depth. Holes with exit diameters up to 10 times smaller than the mask-image diameter are produced in the case of perforation during the appropriate process phase determined b...

  20. Influence of laser beam’s image-plane position on geometry of through-holes in percussion-drilled glass using excimer laser

    Directory of Open Access Journals (Sweden)

    Ales Babnik

    2013-01-01

    Full Text Available We study the influence of a laser beam’s image-plane position relative to the processed surface for the deep-hole, laser-microdrilling of soda-lime glass with an excimer 308-nm laser and mask-projection technique. It is demonstrated that the image-plane position has a significant influence on the hole’s tapering and final depth. Holes with exit diameters up to 10 times smaller than the mask-image diameter are produced in the case of perforation during the appropriate process phase determined by the formation of the plasma plume.

  1. Study on excimer laser irradiation for controlled dehydrogenation and crystallization of boron doped hydrogenated amorphous/nanocrystalline silicon multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Gontad, F., E-mail: fran_gontad@yahoo.es [Applied Physics Department, University of Vigo, E.I. Industrial, Campus de As Lagoas, Marcosende, E-36310, Vigo (Spain); Conde, J.C. [Applied Physics Department, University of Vigo, E.I. Industrial, Campus de As Lagoas, Marcosende, E-36310, Vigo (Spain); Filonovich, S.; Cerqueira, M.F.; Alpuim, P. [Department of Physics, University of Minho, Campus de Azurém, 4800-058 Guimarães (Portugal); Chiussi, S. [Applied Physics Department, University of Vigo, E.I. Industrial, Campus de As Lagoas, Marcosende, E-36310, Vigo (Spain)

    2013-06-01

    We report on the excimer laser annealing (ELA) induced temperature gradients, allowing controlled crystallization and dehydrogenation of boron-doped a-Si:H/nc-Si:H multilayers. Depth of the dehydrogenation and crystallization process has been studied numerically and experimentally, showing that temperatures below the monohydride decomposition can be used and that significant changes of the doping profile can be avoided. Calculation of temperature profiles has been achieved through numerical modeling of the heat conduction differential equation. Increase in the amount of nano-crystals, but not in their size, has been demonstrated by Raman spectroscopy. Effective dehydrogenation and shape of the boron profile have been studied by time of flight secondary ion mass spectroscopy. The relatively low temperature threshold for dehydrogenation, below the monohydride decomposition temperature, has been attributed to both, the large hydrogen content of the original films and the partial crystallization during the ELA process. The results of this study show that UV-laser irradiation is an effective tool to improve crystallinity and dopant activation in p{sup +}-nc-Si:H films without damaging the substrate. - Highlights: • An efficient dehydrogenation is possible through excimer laser annealing. • 140 mJ/cm{sup 2} is enough for dehydrogenation without significant changes in doping profile. • Fluences up to 300 mJ/cm{sup 2} promote partial crystallization of the amorphous structures.

  2. Excimer laser recrystallization of nanocrystalline-Si films deposited by inductively coupled plasma chemical vapour deposition at 150 deg. C

    International Nuclear Information System (INIS)

    Polycrystalline silicon thin film transistors (poly-Si TFTs) fabricated at low temperature (under 200 deg. C) have been widely investigated for flexible substrate applications such as a transparent plastic substrate. Unlike the conventional TFT process using glass substrate, the maximum process temperature should be kept less than 200 deg. C in order to avoid thermal damage on flexible substrates. We report the characteristics of nanocrystalline silicon (nc-Si) irradiated by an excimer laser. Nc-Si precursors were deposited on various buffer layers by inductively coupled plasma chemical vapour deposition (ICP-CVD) at 150 deg. C. We employed various buffer layers, such as silicon nitride (SiNX) and silicon dioxide (SiO2), in order to report recrystallization characteristics in connection with a buffer layer of a different thermal conductivity. The dehydrogenation and recrystallization was performed by step-by-step excimer laser annealing (ELA) (XeCl,λ=308 nm) in order to prevent the explosive release of hydrogen atoms. The grain size of the poly-Si film, which was recrystallized on the various buffer layers, was measured by scanning electron microscopy (SEM) at each laser energy density. The process margin of step-by-step ELA employing the SiNX buffer layer is wider than SiO2 and the maximum grain size slightly increased

  3. Excimer laser recrystallization of nanocrystalline-Si films deposited by inductively coupled plasma chemical vapour deposition at 150 deg. C

    Energy Technology Data Exchange (ETDEWEB)

    Park, Joong-Hyun [School of Electrical Engineering (50), Seoul National University, Shinlim-Dong, Gwanak-Gu, Seoul (Korea, Republic of); Han, Sang-Myeon [School of Electrical Engineering (50), Seoul National University, Shinlim-Dong, Gwanak-Gu, Seoul (Korea, Republic of); Park, Sang-Geun [School of Electrical Engineering (50), Seoul National University, Shinlim-Dong, Gwanak-Gu, Seoul (Korea, Republic of); Han, Min-Koo [School of Electrical Engineering (50), Seoul National University, Shinlim-Dong, Gwanak-Gu, Seoul (Korea, Republic of); Shin, Moon-Young [LTPS Team, AMLCD Business, Samsung Electronics Co., Giheung, Yongin City (Korea, Republic of)

    2006-09-01

    Polycrystalline silicon thin film transistors (poly-Si TFTs) fabricated at low temperature (under 200 deg. C) have been widely investigated for flexible substrate applications such as a transparent plastic substrate. Unlike the conventional TFT process using glass substrate, the maximum process temperature should be kept less than 200 deg. C in order to avoid thermal damage on flexible substrates. We report the characteristics of nanocrystalline silicon (nc-Si) irradiated by an excimer laser. Nc-Si precursors were deposited on various buffer layers by inductively coupled plasma chemical vapour deposition (ICP-CVD) at 150 deg. C. We employed various buffer layers, such as silicon nitride (SiN{sub X}) and silicon dioxide (SiO{sub 2}), in order to report recrystallization characteristics in connection with a buffer layer of a different thermal conductivity. The dehydrogenation and recrystallization was performed by step-by-step excimer laser annealing (ELA) (XeCl,{lambda}=308 nm) in order to prevent the explosive release of hydrogen atoms. The grain size of the poly-Si film, which was recrystallized on the various buffer layers, was measured by scanning electron microscopy (SEM) at each laser energy density. The process margin of step-by-step ELA employing the SiN{sub X} buffer layer is wider than SiO{sub 2} and the maximum grain size slightly increased.

  4. High Efficiency Mask Based Laser Materials Processing with TEA-CO2 - and Excimer Laser

    DEFF Research Database (Denmark)

    Bastue, Jens; Olsen, Flemmming Ove

    1997-01-01

    In general, mask based laser materials processing techniques suffer from a very low energy efficiency. We have developed a simple device called an energy enhancer, which is capable of increasing the energy efficiency of typical mask based laser materials processing systems. A short review of the...

  5. Short-term Effects of 308-nm Xenon-chloride Excimer Laser and Narrow-band Ultraviolet B in the Treatment of Vitiligo: A Comparative Study

    OpenAIRE

    Hong, Seok-Beom; Park, Hyun-Ho; Lee, Mu-Hyoung

    2005-01-01

    We compared the clinical efficacy of a short-term intervention of 308-nm excimer laser with that of narrow-band UVB (NBUVB) phototherapy for vitiligo patients to see the early response. Twenty-three symmetrically patterned patches of vitiligo on 8 patients were selected. Vitiligo patches on one side of the body were treated 2 times per week for a maximum of 20 treatments with the excimer laser, and NBUVB phototherapy was used on patches on the other side. Improvement (repigmentation) was asse...

  6. Time-resolved diagnostics of excimer laser-generated ablation plasmas used for pulsed laser deposition

    International Nuclear Information System (INIS)

    Characteristics of laser plasmas used for pulsed laser deposition (PLD) of thin films are examined with four in situ diagnostic techniques: Optical emission spectroscopy, optical absorption spectroscopy, ion probe studies, and gated ICCD (intensified charge-coupled-device array) fast photography. These four techniques are complementary and permit simultaneous views of the transport of ions, excited states, ground state neutrals and ions, and hot particulates following KrF laser ablation of YBCO, BN, graphite and Si in vacuum and background gases. The implementation and advantages of the four techniques are first described in order to introduce the key features of laser plasmas for pulsed laser deposition. Aspects of the interaction of the ablation plume with background gases (i.e., thermalization, attenuation, shock formation) and the collision of the plasma plume with the substrate heater are then summarized. The techniques of fast ICCD photography and gated photon counting are then applied to investigate the temperature, velocity, and spatial distribution of hot particles generated during KrF ablation of YBCO, BN, Si and graphite. Finally, key features of fast imaging of the laser ablation of graphite into high pressure rare gases are presented in order to elucidate internal reflected shocks within the plume, redeposition of material on a surface, and formation of hot nanoparticles within the plume

  7. Ablation behavior and constraints on the U–Pb and Th–Pb geochronometers in titanite analyzed by quadrupole inductively coupled plasma mass spectrometry coupled to a 193 nm excimer laser

    International Nuclear Information System (INIS)

    U–Th–Pb geochronology of titanite by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is a promising technique to constrain the history of igneous and metamorphic rocks. However, the quality of the resulting ages depends strongly on protocol adopted for the analyses and data reduction. There is no general agreement on the laser ablation settings and methodology that should be applied for titanite LA-ICP-MS geochronology. In particular it is essential to define an analytical procedure that could minimize the elemental fractionation for titanite U–Th–Pb geochronology, and to evaluate if non matrix-matched standards and samples (e.g. zircon and titanite) are suitable to obtain precise and accurate ages. In this study, ablation experiments were carried out in spot mode using an ArF 193 nm excimer laser coupled to a quadrupole ICP-MS, with varying fluence, spot size and repetition rate conditions. The ablation behavior of the Khan titanite reference material was described in details and compared to the Plešovice zircon standard. The ratio-of-the-mean intensity method was used for data reduction. Three sources of fractionation and systematic errors between zircon and titanite are considered together: mass bias coefficients, shape of the time-dependent fractionation, and differences of ablated volumes. Even if the laser-induced elemental fractionation and matrix effects can be minimized between the Plešovice zircon standard and the Khan titanite, a matrix-matched standardization with a titanite standard is required for precise U–Th–Pb titanite ages, as well as at low frequency and fluence conditions. - Highlights: • This study presents ablation experiments on Khan titanite compared Plešovice zircon. • Matrix effects related to laser induced elemental fractionation are monitored. • Low frequency and fluence conditions are required for precise U–Th–Pb titanite data. • The Khan titanite can hardly be substituted by a zircon

  8. AFM study of excimer laser patterning of block-copolymer: Creation of ordered hierarchical, hybrid, or recessed structures

    Science.gov (United States)

    Švanda, Jan; Siegel, Jakub; Švorčík, Vaclav; Lyutakov, Oleksiy

    2016-05-01

    We report fabrication of the varied range of hierarchical structures by combining bottom-up self-assembly of block copolymer poly(styrene-block-vinylpyridine) (PS-b-P4VP) with top-down excimer laser patterning method. Different procedures were tested, where laser treatment was applied before phase separation and after phase separation or phase separation and surface reconstruction. Laser treatment was performed using either polarized laser light with the aim to create periodical pattern on polymer surface or non-polarized light for preferential removing of polystyrene (PS) part from PS-b-P4VP. Additionally, dye was introduced into one part of block copolymer (P4VP) with the aim to modify its response to laser light. Resulting structures were analyzed by XPS, UV-vis and AFM techniques. Application of polarized laser light leads to creation of structures with hierarchical, recessed or hybrid geometries. Non-polarized laser beam allows pronouncing the block copolymer phase separated structure. Tuning the order of steps or individual step conditions enables the efficient reorientation of block-copolymer domain at large scale, fabrication of hierarchical, hybrid or recessed structures. The obtained structures can find potential applications in nanotechnology, photonics, plasmonics, information storage, optical devices, sensors and smart surfaces.

  9. Study on the surface chemical properties of UV excimer laser irradiated polyamide by XPS, ToF-SIMS and CFM

    International Nuclear Information System (INIS)

    Polyamide (nylon 6) was irradiated by a pulsed ultraviolet (UV) excimer laser with a fluence below its ablation threshold. Chemical modifications on laser treated nylon were studied by X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (Tof-SIMS) and chemical force microscopy (CFM). XPS study provides information about changes in chemical composition and the chemical-state of atom types on the fiber surface. The high sensitivity of ToF-SIMS to the topmost layers was used to detect crosslinking after the laser treatment. Gold-coated AFM tips modified with -COOH terminated self-assembled alkanethiol monolayers (SAMs) were used to measure adhesion forces on the untreated and laser treated samples. XPS results revealed that the irradiated samples have higher oxygen content than prior to laser irradiation. Tof-SIMS analysis illustrated that carbonyl groups in nylon 6 decrease significantly but hydroxyl groups increase after low-fluence laser irradiation. The adhesion force measurements by CFM showed spatial distribution of hydroxyl groups on nylon 6 after the laser treatment

  10. Study on the surface chemical properties of UV excimer laser irradiated polyamide by XPS, ToF-SIMS and CFM

    Science.gov (United States)

    Yip, Joanne; Chan, Kwong; Sin, Kwan Moon; Lau, Kai Shui

    2003-01-01

    Polyamide (nylon 6) was irradiated by a pulsed ultraviolet (UV) excimer laser with a fluence below its ablation threshold. Chemical modifications on laser treated nylon were studied by X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (Tof-SIMS) and chemical force microscopy (CFM). XPS study provides information about changes in chemical composition and the chemical-state of atom types on the fiber surface. The high sensitivity of ToF-SIMS to the topmost layers was used to detect crosslinking after the laser treatment. Gold-coated AFM tips modified with COOH terminated self-assembled alkanethiol monolayers (SAMs) were used to measure adhesion forces on the untreated and laser treated samples. XPS results revealed that the irradiated samples have higher oxygen content than prior to laser irradiation. Tof-SIMS analysis illustrated that carbonyl groups in nylon 6 decrease significantly but hydroxyl groups increase after low-fluence laser irradiation. The adhesion force measurements by CFM showed spatial distribution of hydroxyl groups on nylon 6 after the laser treatment.

  11. Sub-micron period grating structures in Ta2O5 and InOx thin oxide films fabricated using 248nm interferometric excimer laser ablation

    OpenAIRE

    Pissadakis, S.; Reekie, L.; J. S. Wilkinson; Kiriakidis, G.

    2000-01-01

    High quality relief gratings of period 500nm have been patterned in InOx and Ta2O5 thin films using interferometric 248nm excimer laser ablation. Details of the ablation process and the morphology of the gratings are presented.

  12. Magnetic pulse compression in the prepulse circuit for a 1 kW, 1kHz XeCl excimer laser

    OpenAIRE

    Ekelmans, G.B.; Goor, van, H.; Trentelman, M.; Witteman, W.J.

    1991-01-01

    Using high quality low loss ferrite, a single stage magnetic pulse compression network has been demonstrated working at 1 kHz PRF. A pulse compression factor of 4 has been achieved, delivering a 50 ns pulse as prepulse in the excitation circuit for a high power XeC1-excimer laser.

  13. Percutaneous coronary excimer laser angioplasty in patients with stable and unstable angina pectoris. Acute results and incidence of restenosis during 6-month follow-up.

    Science.gov (United States)

    Karsch, K R; Haase, K K; Voelker, W; Baumbach, A; Mauser, M; Seipel, L

    1990-06-01

    A clinical study was conducted to evaluate the efficacy and safety of percutaneous coronary excimer laser angioplasty in 60 patients with coronary artery disease. Forty-nine patients had stable exertional angina, and 11 patients had unstable angina despite medical therapy. A novel 1.4-mm diameter catheter with 20 quartz fibers of 100-microns diameter each arranged concentrically around a central lumen suitable for a 0.014-in. flexible guide wire was coupled to an excimer laser. A commercial excimer laser emitting energy at a wavelength of 308 nm with a pulse duration of 60 nsec was used. The laser was operated at 20 Hz. Mean energy transmission was 30 +/- 5 mJ/mm2. In five of the 60 patients, laser angioplasty was not attempted. In 23 patients with laser ablation alone, percent stenosis decreased from 76 +/- 14% before to 27 +/- 17% after ablation and was 34 +/- 15% at the early follow-up angiogram. In 32 patients, additional balloon angioplasty was performed because of vessel closure after laser ablation in 11 and an insufficient qualitative result in 21 patients. Of the 11 patients with unstable angina, one patient died due to vessel closure 3 hours after intervention, and two patients developed a myocardial infarction. In 22 of 47 patients with late follow-up angiography, restenosis within the 6-month follow-up period occurred. Rate of restenosis was higher in patients treated with laser ablation and balloon angioplasty (16 of 28) than in patients treated with laser ablation alone (six of 19). These results suggest that coronary excimer laser angioplasty for ablation of obstructive lesions is feasible and safe in patients with stable angina. However, development of new catheter systems is necessary for an improved success rate. PMID:2344680

  14. Development of a Silicon Based Electron Beam Transmission Window for Use in a KrF Excimer Laser System

    International Nuclear Information System (INIS)

    The Princeton Plasma Physics Laboratory (PPPL), in collaboration with the Naval Research Laboratory (NRL), is currently investigating various novel materials (single crystal silicon, , and ) for use as electron-beam transmission windows in a KrF excimer laser system. The primary function of the window is to isolate the active medium (excimer gas) from the excitation mechanism (field-emission diodes). Chosen window geometry must accommodate electron energy transfer greater than 80% (750 keV), while maintaining structural integrity during mechanical load (1.3 to 2.0 atm base pressure differential, approximate 0.5 atm cyclic pressure amplitude, 5 Hz repetition rate) and thermal load across the entire hibachi area (approximate 0.9 W · cm superscript ''-2''). In addition, the window must be chemically resistant to attack by fluorine free-radicals (hydrofluoric acid, secondary). In accordance with these structural, functional, and operational parameters, a 22.4 mm square silicon prototype window, coated with 500 nm thin-film silicon nitride (Si3N4), has been fabricated. The window consists of 81 square panes with a thickness of 0.019 mm ± 0.001 mm. Stiffened (orthogonal) sections are 0.065 mm in width and 0.500 mm thick (approximate). Appended drawing (Figure 1) depicts the window configuration. Assessment of silicon (and silicon nitride) material properties and CAD modeling and analysis of the window design suggest that silicon may be a viable solution to inherent parameters and constraints

  15. Excimer laser phototherapeutic keratectomy : Indications, results and its role in the Indian scenario

    Directory of Open Access Journals (Sweden)

    Rao Srinivas

    1999-01-01

    Full Text Available PURPOSE: To report indications, technique, and results of excimer phototherapeutic keratectomy (PTK, and describe possible reasons for the small numbers of such procedures performed in a referral institute in India. METHODS: Retrospective review of case records of 10 patients (11 eyes who underwent excimer PTK at our institute between February 1994 and September 1997. RESULTS: Corneal scars were the most common indication for treatment. Best-corrected visual acuity (BCVA improved in 6 eyes (mean: 2 lines of Snellen acuity. All eyes had BCVA > or = 6/12 after treatment. None of the patients experienced loss of BCVA after treatment. Unaided visual acuity improved in 3 eyes and decreased in 2 eyes. Change in spherical equivalent refraction > or = 1 diopter occurred in 77.8% of eyes after treatment. Treating central corneal scars resulted in a significant hyperopic shift in refraction. CONCLUSIONS: Excimer PTK is a safe and effective procedure for the treatment of superficial corneal opacities. Post-treatment ametropia may require further correction with optical aids. Inappropriate referrals, deep corneal scars, and cost of the procedure could have contributed to the small numbers of PTK performed at our institute. Improved understanding of procedural strengths and limitations could lead to increased use of this procedure, with satisfying results in selected patients.

  16. Excimer laser processing of inkjet-printed and sputter-deposited transparent conducting SnO{sub 2}:Sb for flexible electronics

    Energy Technology Data Exchange (ETDEWEB)

    Cranton, Wayne M. [School of Computing and Informatics, Nottingham Trent University, Nottingham, NG11 8NS (United Kingdom)], E-mail: wayne.cranton@ntu.ac.uk; Wilson, Sharron L.; Ranson, Robert; Koutsogeorgis, Demosthenes C. [School of Computing and Informatics, Nottingham Trent University, Nottingham, NG11 8NS (United Kingdom); Chi Kuangnan [Patterning Technologies Ltd., 58 Shrivenham Hundred Business Park, Watchfield, Oxon, SN6 8TY (United Kingdom)], E-mail: kuangnan.chi@pattech.com; Hedgley, Richard; Scott, John [Patterning Technologies Ltd., 58 Shrivenham Hundred Business Park, Watchfield, Oxon, SN6 8TY (United Kingdom); Lipiec, Stephen [Keeling and Walker Limited, Whieldon Road, Stoke-on-Trent, Staffordshire, ST4 4JA (United Kingdom)], E-mail: s.lipiec@keelingwalker.co.uk; Spiller, Andrew [Keeling and Walker Limited, Whieldon Road, Stoke-on-Trent, Staffordshire, ST4 4JA (United Kingdom); Speakman, Stuart [MDSL 7 Chapel Drive, Little Waltham, Chelmsford, Essex, CM3 3LW (United Kingdom)], E-mail: sps7859@btconnect.com

    2007-10-15

    The feasibility of low-temperature fabrication of transparent electrode elements from thin films of antimony-doped tin oxide (SnO{sub 2}:Sb, ATO) has been investigated via inkjet printing, rf magnetron sputtering and post-deposition excimer laser processing. Laser processing of thin films on both glass and plastic substrates was performed using a Lambda Physik 305i excimer laser, with fluences in the range 20-100 mJ cm{sup -2} reducing sheet resistance from as-deposited values by up to 3 orders of magnitude. This is consistent with TEM analysis of the films that shows a densification of the upper 200 nm of laser-processed regions.

  17. Numerical simulation on the temperature field induced by a nanosecond pulsed excimer laser in the phase-change film

    International Nuclear Information System (INIS)

    In the paper, a three-dimensional finite element model was developed to demonstrate the temperature field induced by a nanosecond pulsed excimer laser in the phase-change film. The numerical model was established with an assumed rectangular temporal profile, following the continuous medium heat conduction theory with semi-infinity heat conduction. It showed that the temperature variation followed the exponential relation in both the heating/cooling procedures, and the whole heating/cooling process was divided into four regions I–IV, namely rapid heating region I and equilibrium heating region II in the heating process as well as quick cooling region III and equilibrium cooling region IV in the cooling process. The heating/cooling rates were then fitted from the temperature variation curve. The calculated heating/cooling rates were in the scale of 108–1011 K/s for the nano-scale pulse radiance. Furthermore, the effects of laser fluence and pulse duration on the temperature field were investigated. It was noted that the effect of pulse duration was focused on regions II and III, while the heating rate in region I was mainly determined by laser fluence. - Highlights: • A finite element model was developed in the paper. • The temperature field induced by a short pulse laser was elucidated. • The heating/cooling rates were obtained in the scale of 108–1011 K/s. • The effects of laser fluence and pulse duration were also studied

  18. New-Generation Hybrid Contact Lens for the Management of Extreme Irregularity in a Thin Cornea After Unsuccessful Excimer Laser Refractive Surgery

    OpenAIRE

    Piñero Llorens, David Pablo; Pérez Cambrodí, Rafael J.; Ruiz Fortes, Pedro; Blanes Mompó, Francisco J.

    2014-01-01

    Purpose: To report a very successful outcome obtained with the fitting of a new-generation hybrid contact lens of reverse geometry in a thin cornea with extreme irregularity due to the presence of a central island after unsuccessful myopic excimer laser refractive surgery. Methods: A 32-year-old man attended to our clinic complaining of very poor vision in his right eye after bilateral laser in situ keratomileusis (treatment or surgery) for myopia correction and some additional retreatments a...

  19. Laser-induced front side and back side etching of fused silica with KrF and XeF excimer lasers using metallic absorber layers: A comparison

    International Nuclear Information System (INIS)

    Highlights: ► We study laser-induced front and back side etching of fused silica with a KrF and a XeF excimer laser. ► Chromium layers as absorber are used. ► The LIFE method allows nm-precision etching with etching depths up to 300 nm. ► The measurement results are compared to the results calculated by a thermal model. - Abstract: Laser-induced front side (LIFE) and back side etching (LIBDE) are methods for nanometer-precision laser etching of transparent materials using thin absorber layers. The etching behaviour of fused silica at a laser wavelength of 248 nm (KrF) and 351 nm (XeF excimer laser) with a pulse duration of 25 ns using a chromium absorber layer was analysed and compared for front and back side etching geometry. For both wavelengths as well as for both processes the etching depth d increases almost linearly in dependence on the laser fluence (it is: d ≈ δ*(Φ − Φth)). The etching depth at the same laser fluence is higher for 248 nm compared to 351 nm as well as for back side etching compared to the front side etching process (LIFE: δ(248 nm) = 20 nm/(J/cm2), δ(351 nm) = 15 nm/(J/cm2), LIBDE: δ(248 nm) = 38 nm/(J/cm2), δ(351 nm) = 8 nm/(J/cm2) with Φth,m from 0.3 to 2.65 J/cm2). Furthermore, the measured depths were evaluated with the estimated etching depth calculated by a thermal model. The simple thermodynamic model allows a good qualitative description of the etching depth behaviour; however, the model does not allow the quantitative calculation of the etching depth.

  20. Vacuum ultraviolet argon excimer laser excited by optical-field-induced ionized electrons produced in an argon-filled hollow fiber

    Science.gov (United States)

    Kubodera, Shoichi; Kaku, Masanori; Katto, Masahito

    2011-10-01

    Short-wavelength lasers in the vacuum ultraviolet (VUV) spectral region between 100 and 200 nm have not yet been developed to the same degree as visible and infrared lasers. We have demonstrated the production of argon excimers via an optical-field-induced ionization (OFI) process by using a high-intensity infrared laser. We here report optical amplification of argon excimers at the wavelength of 126 nm by producing an extended OFI plasma inside an argon-filled hollow fiber with an inner diameter of 250 microns with a length of 5.0 cm. A gain-length product of 4.3 through the use of single-pass amplification with VUV optics was observed, indicating a small signal gain coefficient of 0.86 cm-1 with an uncertainty of 0.03. It was found that the hollow fiber served to extend the OFI plasma length and to guide the excitation of the infrared laser and the produced VUV emissions at 126 nm, but did not affect the OFI plasma conditions to produce argon excimer molecules. Short-wavelength lasers in the vacuum ultraviolet (VUV) spectral region between 100 and 200 nm have not yet been developed to the same degree as visible and infrared lasers. We have demonstrated the production of argon excimers via an optical-field-induced ionization (OFI) process by using a high-intensity infrared laser. We here report optical amplification of argon excimers at the wavelength of 126 nm by producing an extended OFI plasma inside an argon-filled hollow fiber with an inner diameter of 250 microns with a length of 5.0 cm. A gain-length product of 4.3 through the use of single-pass amplification with VUV optics was observed, indicating a small signal gain coefficient of 0.86 cm-1 with an uncertainty of 0.03. It was found that the hollow fiber served to extend the OFI plasma length and to guide the excitation of the infrared laser and the produced VUV emissions at 126 nm, but did not affect the OFI plasma conditions to produce argon excimer molecules. Part of this work has been supported by

  1. Microfeature edge quality enhancement in excimer laser micromachining of metal films by coating with a sacrificial polymer layer

    International Nuclear Information System (INIS)

    A novel technique for enhanced excimer laser micromachining of metallic thin films by first coating the metal film with a thin polymer film is presented. The sacrificial polymer film acts as a protective and a clamping layer, preventing the metal film from undergoing cracking and damage during the laser ablation. The machined patterns are characterized regarding their quality in terms of edge roughness, lateral overcut and boundary integrity in proximity machining. Significant improvement in these aspects is observed when the machining is carried out on metal films coated with thin polymer films. Details of the effects of the fluence and spot overlap on the micromachined patterns are investigated. The technique allows sharp machining of micropatterns on thin metal films, over length scales ranging from hundreds of micrometers down to a single micrometer, thereby proving to be the only technique that can be used to laser micromachine thin films at the length scale of a single micrometer. This technique is expected to be useful for large scale patterning of metallic films, particularly for plasmonic applications and infrared/terahertz metamaterials. (paper)

  2. Three-dimensional simulation of rapid melting and resolidification of thin Si films by excimer laser annealing

    International Nuclear Information System (INIS)

    A model has been developed for the rapid melting and resolidification of thin Si films induced by excimer-laser annealing. The key feature of this model is its ability to simulate lateral growth and random nucleation. The first component of the model is a set of rules for phase change. The second component is a set of functions for computing the latent heat and the displacement of the solid-liquid interface resulting from the phase change. The third component is an algorithm that allows for random nucleation based on classical nucleation theory. Consequently, the model enables the prediction of lateral growth length (LGL), as well as the calculation of other critical responses of the quenched film such as solid-liquid interface velocity and undercooling. Thin amorphous Si films with thickness of 30, 50, and 100 nm were annealed under various laser fluences to completely melt the films. The resulting LGL were measured using a scanning electron microscope. Using physical parameters that were consistent with previous studies, the simulated LGL values agree well with the experimental results over a wide range of irradiation conditions. Sensitivity analysis was done to demonstrate the behavior of the model with respect to a select number of model parameters. Our simulations suggest that, for a given fluence, controlling the film's quenching rate is essential for increasing LGL. To this end, the model is an invaluable tool for evaluating and choosing irradiation strategies for increasing lateral growth in laser-crystallized silicon films

  3. Rapid fabrication of rigid biodegradable scaffolds by excimer laser mask projection technique: a comparison between 248 and 308 nm

    Science.gov (United States)

    Beke, S.; Anjum, F.; Ceseracciu, L.; Romano, I.; Athanassiou, A.; Diaspro, A.; Brandi, F.

    2013-03-01

    High-resolution photocrosslinking of the biodegradable poly(propylene fumarate) (PPF) and diethyl fumarate (DEF), using pulsed laser light at 248 and 308 nm is presented. The curing depth can be modulated between a few hundreds of nm and a few μm when using 248 nm and ten to a hundred μm when using 308 nm. By adjusting the total fluence (pulse numbers×laser fluence) dose and the weight ratios of PPF, DEF, and the photoinitiator in the photocrosslinkable mixtures, the height of polymerized structures can be precisely tuned. The lateral resolution is evaluated by projecting a pattern of a grid with a specified line width and line spacing. Young’s modulus of the cured parts is measured and found to be several GPa for both wavelengths, high enough to support bone formation. Several 2D and 2.5D microstructures, as well as porous 3D scaffolds fabricated by a layer-by-layer method, are presented. The results demonstrate that excimer laser-based photocuring is suitable for the fabrication of stiff and biocompatible structures with defined patterns of micrometer resolution in all three spatial dimensions.

  4. Surface studies on benzophenone doped PDMS microstructures fabricated using KrF excimer laser direct write lithography

    Energy Technology Data Exchange (ETDEWEB)

    Kant, Madhushree Bute; Shinde, Shashikant D. [Department of Physics, University of Pune, Pune 411007 (India); Bodas, Dhananjay [Centre for Nanobioscience, Agharkar Research Institute, Agharkar road, Pune 411004 (India); Patil, K.R. [Center for Materials Characterization, National Chemical Laboratories, Pune 411008 (India); Sathe, V.G. [UGC DAE Inter University Consortium, Indore 452017 (India); Adhi, K.P. [Department of Physics, University of Pune, Pune 411007 (India); Gosavi, S.W., E-mail: swg@physics.unipune.ac.in [Department of Physics, University of Pune, Pune 411007 (India)

    2014-09-30

    Graphical abstract: - Highlights: • Use of KrF Laser micromachining for Lab-On-Chip applications at lower fluence. • Addition of Benzophenone in PDMS enhances its self development sensitivity. • Benzophenone helps efficient energy transfer for equal density of bond scissioning. • Correlation of chemical composition with laser dose and microstructure. • Microstructures with well defined clean sidewalls. - Abstract: This paper discusses microfabrication process for benzophenone doped polydimethylsiloxane (PDMS) using laser lithography. KrF excimer laser of 248 nm with 20 ns pulse width at repetition rate of 1 Hz was used for microfabrication of undoped and benzophenone doped PDMS. The doped-PDMS shows sensitivity below 365 nm, permitting processing under ambient light. The analysis of etch depth revealed that doped PDMS shows self developable sensitivity at lower fluence of ∼250 mJ/cm{sup 2}. The unexposed and exposed surface was studied using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and Scanning electron microscopy (SEM). Spectrocopic analysis indicated increase in C-O, C=O, Si-O{sub 3} and Si-O{sub 4} bonding at the expense of Si-C and Si-O{sub 2} bonds of PDMS. In case of laser exposed doped-PDMS, removal of benzophenone from probe depth of spectroscopy was observed. Whereas the surface morphology of exposed and unexposed doped-PDMS was observed to be same, indicating clean development of PDMS micropatterns. The present study indicates that addition of 3.0 wt.% benzophenone in PDMS enhance self development sensitivity of PDMS. The self developable results on doped-PDMS are quite encouraging for its potential use in point of care Lab-On-Chip applications, for fabricating micropatterns using direct write laser lithography technology.

  5. Surface studies on benzophenone doped PDMS microstructures fabricated using KrF excimer laser direct write lithography

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Use of KrF Laser micromachining for Lab-On-Chip applications at lower fluence. • Addition of Benzophenone in PDMS enhances its self development sensitivity. • Benzophenone helps efficient energy transfer for equal density of bond scissioning. • Correlation of chemical composition with laser dose and microstructure. • Microstructures with well defined clean sidewalls. - Abstract: This paper discusses microfabrication process for benzophenone doped polydimethylsiloxane (PDMS) using laser lithography. KrF excimer laser of 248 nm with 20 ns pulse width at repetition rate of 1 Hz was used for microfabrication of undoped and benzophenone doped PDMS. The doped-PDMS shows sensitivity below 365 nm, permitting processing under ambient light. The analysis of etch depth revealed that doped PDMS shows self developable sensitivity at lower fluence of ∼250 mJ/cm2. The unexposed and exposed surface was studied using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and Scanning electron microscopy (SEM). Spectrocopic analysis indicated increase in C-O, C=O, Si-O3 and Si-O4 bonding at the expense of Si-C and Si-O2 bonds of PDMS. In case of laser exposed doped-PDMS, removal of benzophenone from probe depth of spectroscopy was observed. Whereas the surface morphology of exposed and unexposed doped-PDMS was observed to be same, indicating clean development of PDMS micropatterns. The present study indicates that addition of 3.0 wt.% benzophenone in PDMS enhance self development sensitivity of PDMS. The self developable results on doped-PDMS are quite encouraging for its potential use in point of care Lab-On-Chip applications, for fabricating micropatterns using direct write laser lithography technology

  6. Topography and raytracing analysis of patients with excellent visual acuity 3 months after excimer laser photorefractive keratectomy for myopia.

    Science.gov (United States)

    Maguire, L J; Zabel, R W; Parker, P; Lindstrom, R L

    1991-01-01

    We performed topography and raytracing analysis 3 months after surgery on five consecutive eyes of five patients, which had excimer laser photorefractive keratectomy for myopia. Three of the five eyes had uncorrected postoperative visual acuity of 20/20 or better. Two eyes had an uncorrected vision of 20/40. In three of five eyes, the area of excimer ablation was centered within 1.0 mm of the optical axis. Three other eyes showed decentration that ranged from 1.1 to 1.5 mm. The range of surface power seen within 2 mm of the central keratoscope ring was as follows: patient CK = 37.50 to 39.50 diopters; patient CA = 40.50 D to 44.80 D; patient CW = 37.90 D to 42.20 D; patient AC = 35.50 D to 39.00 D; patient DT = 34.50 D to 41.40 D. Topography patterns differed from eye to eye. A raytracing program modeled refraction of 20/80 and 20/20 "E" of 100%, 50%, 25%, 12.5% and 6.25% contrast through all measured points on the central 10 keratoscope rings of the five postoperative corneas. The five computer-derived images were ranked subjectively according to the observed degree of image degradation by three observers. Two eyes showed discernible 20/20 E's even at the 12.5% contrast level. Little to no ghost image was seen. Two eyes showed degraded but discernible 20/20 letters at higher levels of contrast only. These eyes showed moderate ghost images that were most apparent in the high-contrast 20/80 letters. One eye showed poor resolution of the 100% contrast 20/20 letter and moderately severe ghost images.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2043557

  7. Early outcome of high energy Laser (Excimer) facilitated coronary angioplasty ON hARD and complex calcified and balloOn-resistant coronary lesions: LEONARDO Study

    Energy Technology Data Exchange (ETDEWEB)

    Ambrosini, Vittorio; Sorropago, Giovanni; Laurenzano, Eugenio [Montevergine Clinic, Mercogliano (Italy); Golino, Luca, E-mail: lucagolino.jazz@alice.it [Montevergine Clinic, Mercogliano (Italy); Moriggia-Pelascini Hospital, Gravedona, Como (Italy); Casafina, Alfredo; Schiano, Vittorio [Montevergine Clinic, Mercogliano (Italy); Gabrielli, Gabriele [University Hospital Ospedali Riuniti, Ancona (Italy); Ettori, Federica; Chizzola, Giuliano [Spedali Civili University Hospital, Brescia (Italy); Bernardi, Guglielmo; Spedicato, Leonardo [University Hospital S. Maria Misericordia, Udine (Italy); Armigliato, Pietro [Istituto Italiano Ricerche Mediche, Verona (Italy); Spampanato, Carmine [Telethon Institute of Genetics and Medicine (TIGEM), Naples (Italy); Furegato, Martina [Istituto Italiano Ricerche Mediche, Verona (Italy)

    2015-04-15

    Aim: An innovative xenon–chlorine (excimer) pulsed laser catheter (ELCA X80) has been recently used for the treatment of complex coronary lesions, as calcified stenosis, chronic total occlusions and non-compliant plaques. Such complex lesions are difficult to adequately treat with balloon angioplasty and/or intracoronary stenting. The aim of this study was to examine the acute outcome of this approach on a cohort of patients with coronary lesions. Methods and Results: Eighty patients with 100 lesions were enrolled through four centers, and excimer laser coronary angioplasty was performed on 96 lesions (96%). Safety and effectiveness data were compared between patients treated with standard laser therapy and those treated with increased laser therapy. Laser success was obtained in 90 lesions (93.7%), procedural success was reached in 88 lesions (91.7%), and clinical success in was obtained in 87 lesions (90.6%). There was no perforation, major side branch occlusion, spasm, no-reflow phenomenon, dissection nor acute vessel closure. Increased laser parameters were used successfully for 49 resistant lesions without complications. Conclusions: This study suggests that laser-facilitated coronary angioplasty is a simple, safe and effective device for the management of complex coronary lesions. Furthermore, higher laser energy levels delivered by this catheter improved the device performance without increasing complications. - Highlights: • We planned this multicenter study to examine the acute outcome of an innovative xenon–chlorine (excimer) pulsed laser catheter (ELCA X80) for treatment of complex coronary lesions. • We enrolled 80 patients with 100 lesions and performed excimer laser coronary angioplasty in 96 lesions (96%). • Laser success was obtained in 90 lesions (93.7%), procedural success was reached in 88 lesions (91.7%), and clinical success was obtained in 87 lesions (90.6%). • Increased laser parameters were used successfully for 49 resistant

  8. Measurement of radiation and temperature of cathod spots in excimer laser discharge; Ekishima reza reiki hodennai ni fukumareru inkyoku kiten no kogakuteki kansoku to ondo no sokutei

    Energy Technology Data Exchange (ETDEWEB)

    Minamitani, Y.; Nakatani, H. [Mitsubishi Electric Corp., Tokyo (Japan)

    1996-08-20

    Excimer laser is used in various fields such as luminous source for steppers, annealing treatment, ablation process, nuclear fusion and so on. In this paper, the radiation timing and gas temperature of cathode spots, streamer discharges and glow discharges in KrF excimer are measured by observing the radiating spectra thereof. The following conclusions are obtained from the results of the present study. Cathode spots begin to radiate at about 20ns after the discharge initiation, then the first and second radiation peaks are observed respectively when the discharge current reversing after passing zero point and the reserved discharged current approaching zero point. Streamer discharge makes flashover between electrodes at the second radiation peak of cathode spots, while the glow discharges almost disappear when streamer discharges occurring. The temperatures of cathode spots and glow discharge as 5500K and 2600K respectively are almost constant and independent upon the discharging voltage of laser. 14 refs., 12 figs.

  9. Excimer laser phototherapeutic keratectomy in eyes with anterior corneal dystrophies: preoperative and postoperative ultrasound biomicroscopic examination and short-term clinical outcomes with and without an antihyperopia treatment.

    OpenAIRE

    Rapuano, Christopher J.

    2003-01-01

    PURPOSE: To evaluate the use of high-frequency ultrasound biomicroscopy (UBM) in determining the depth of corneal pathology in eyes undergoing excimer laser phototherapeutic keratectomy (PTK) for primary or recurrent anterior stromal corneal dystrophies. Corneal clarity, visual acuity and refractive changes in eyes with and without an antihyperopia treatment were also analyzed. METHODS: Twenty eyes of 14 patients with anterior stromal corneal dystrophies were treated with PTK. Eyes were evalu...

  10. Enhanced electrical and optical properties of room temperature deposited Aluminium doped Zinc Oxide (AZO) thin films by excimer laser annealing

    Science.gov (United States)

    El hamali, S. O.; Cranton, W. M.; Kalfagiannis, N.; Hou, X.; Ranson, R.; Koutsogeorgis, D. C.

    2016-05-01

    High quality transparent conductive oxides (TCOs) often require a high thermal budget fabrication process. In this study, Excimer Laser Annealing (ELA) at a wavelength of 248 nm has been explored as a processing mechanism to facilitate low thermal budget fabrication of high quality aluminium doped zinc oxide (AZO) thin films. 180 nm thick AZO films were prepared by radio frequency magnetron sputtering at room temperature on fused silica substrates. The effects of the applied RF power and the sputtering pressure on the outcome of ELA at different laser energy densities and number of pulses have been investigated. AZO films deposited with no intentional heating at 180 W, and at 2 mTorr of 0.2% oxygen in argon were selected as the optimum as-deposited films in this work, with a resistivity of 1×10-3 Ω.cm, and an average visible transmission of 85%. ELA was found to result in noticeably reduced resistivity of 5×10-4 Ω.cm, and enhancing the average visible transmission to 90% when AZO is processed with 5 pulses at 125 mJ/cm2. Therefore, the combination of RF magnetron sputtering and ELA, both low thermal budget and scalable techniques, can provide a viable fabrication route of high quality AZO films for use as transparent electrodes.

  11. Studies of free radicals by ultraviolet excimer laser photolysis. Progress report, 1 April 1980-1 November 1980

    International Nuclear Information System (INIS)

    An experimental technique has been developed to produce and directly study vibrationally excited free radicals. Pulses of light from an ultraviolet excimer laser are used to photodissociate small molecules to generate free radicals with high internal excitation. The radicals are detected directly by the technique of time and wavelength-resolved infrared emission spectroscopy using a background-limited copper-doped germanium infrared detector. New results have been obtained on the CH3 radical. A complete spectrum of the CH3 umbrella band reveals for the first time accurate positions of the vibrational progression in this band. Photofragmentation of (CH3)2Hg has yielded detailed information on the vibrational distribution, rotational temperature, and deactivation rates of the CH3 stretch mode. A technique to study chemical chain reactions using low power, radical-specific, laser initiation and realtime kinetics detection had previously been demonstrated. The results provide a general method to study a large number of chain reaction combustion systems in greater detail. New results on more complex chain reactions such as Cl2/butane reveal that highly detailed infrared emission spectra of various products of the chain and their time evolution is possible. Partitioning of energy between vibrational degrees of freedom and translational heating is obtained over the course of the combustion

  12. An open label pilot study of supraerythemogenic excimer laser in combination with clobetasol spray and calcitriol ointment for the treatment of generalized plaque psoriasis.

    Science.gov (United States)

    Levin, Ethan; Nguyen, Catherine M; Danesh, Melissa J; Beroukhim, Kourosh; Leon, Argentina; Koo, John

    2016-06-01

    A common therapeutic modality for psoriasis includes the combination of phototherapy with topical treatments. The recent development of targeted phototherapy with the excimer laser and spray formulations for topical treatments has increased the efficacy and convenience of these combinational therapies. Herein, we aim to assess the efficacy of a novel combination of therapies using the 308 nm excimer laser, clobetasol propionate spray and calcitriol ointment for the treatment of moderate to severe generalized psoriasis. In this 12-week study, patients with moderate to severe psoriasis received twice weekly treatments with a 308-nm excimer laser combined with clobetasol proprionate twice daily for a month followed by calcitriol ointment twice daily for the next month. Of the 30 patients enrolled, 83% of patients (25/30) achieved PASI-75 [65-94%, 95% confidence interval (CI)] at week 12. For PGA, there was an estimated decrease of 3.6 points (3.1-4.1, 95% CI, p psoriasis. Further evaluation may be conducted with a larger study inclusive of control groups and head-to-head comparisons against topical steroid and UVB therapy as monotherapies. PMID:26329774

  13. Multiplex rotational CARS of nitrogen, oxygen and carbon monoxide with excimer pumped dye lasers: species identification and thermometry in the intermediate temperature range with high temporal and spatial resolution

    OpenAIRE

    Dick, Bernhard; Gierulski, A.

    1986-01-01

    Pure rotational CARS spectra of N2, O2, air, and CO were obtained using excimer laser-pumped dye-lasers. The combination of the folded BOXCARS phase matching geometry with the broad-band laser multiplex method allowed high spatial and temporal resoln. Species and concn. anal. as well as thermometry up to 700 K were demonstrated, and possible applications are discussed.

  14. Properties of the ablation process for excimer laser ablation of Y sub 1 Ba sub 2 Cu sub 3 O sub 7

    Energy Technology Data Exchange (ETDEWEB)

    Neifeld, R.A.; Potenziani, E. (United States Army, Electronics Technology and Devices Laboratory, Fort Monmouth, New Jersey 07703-5000 (US)); Sinclair, W.R. (Martin Goffman Associates, 3 Dellview Drive, Edison, New Jersey 08820-2545 (US)); Hill III, W.T.; Turner, B.; Pinkas, A. (Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742 (US))

    1991-01-15

    The process of excimer laser ablation has been studied while varying the laser fluence from 0.237 to 19.1 J/cm{sup 2}. Ion time-of-flight, total charge, target etch depth per pulse, and etch volume per pulse have been measured. Results indicate a maximum ablation volume and minimum ionization fraction occur near 5 J/cm{sup 2}. Several of the parameters measured vary rapidly in the 1--5 J/cm{sup 2} range. Variation in these parameters strongly influences the properties of films grown by this technique.

  15. A model of the optical energy output of an excimer laser

    Energy Technology Data Exchange (ETDEWEB)

    Naidenkov, I. (Institut Fiziki, Tartu (Estonian SSR))

    1989-01-01

    The properties of a low-signal nonlinear laser model are investigated using a numerical simulation. Some problems encountered during an attempt to apply the model for practical purposes are briefly reviewed with particular reference to the problem of model parameter determination; ways to overcome these problems are discussed. It is noted that knowledge of the laser gain saturation, absorption coefficient, and low signal gain is recommended for laser design and diagnostics.

  16. Análise da pressão intra-ocular após ceratectomia fotorrefrativa com excimer laser Intraocular pressure analysis after excimer laser photorefractive keratectomy

    Directory of Open Access Journals (Sweden)

    Christiane Rolim de Moura

    2000-04-01

    Full Text Available Objetivo: Comparar os valores pré-operatórios da pressão intra-ocular (Po com os valores pós-operatórios em pacientes submetidos à ceratectomia fotorrefrativa com excimer laser, bem como, avaliar os efeitos do uso de corticosteróide tópico na Po nesse grupo.Pacientes e métodos: Foram analisados retrospectivamente 122 pacientes submetidos à ceratectomia fotorrefrativa com excimer laser para correção de miopia, no período de fevereiro de 1994 a dezembro de 1996. Esse grupo teve sua Po tomada com o tonômetro de aplanação de Goldmann no pré-operatório, 30º e 60º dias e sexto mês pós-operatório. Receberam cuidados pós-operatórios padronizados, incluindo o uso de corticosteróide tópico.Resultados: Foi observado um aumento estatisticamente significante em relação aos valores pré-operatórios nas médias da Po no 30º dia pós-operatório, ao passo que no pós-operatório de seis meses obteve-se diminuição estatisticamente significante nos valores médios da Po em relação ao pré-operatório.Conclusão:Nas fases iniciais do período pré-operatório, observou-se um aumento da Po possivelmente relacionado ao uso de corticosteróides. Após 6 meses, os valores da Po foram estatisticamente menores que os pré-operatórios.Purpose: To compare the preoperative and postoperative values of IOP in a group of patients after photorefractive keratectomy (PRK and to evaluate the sensitivy to steroid drops. Methods:One hundred and twenty-two patients who un-derwent PRK from February 1994 to December 1996 were analized retrospectively. IOP measurements were taken with a Goldmann applanation tonometer preoperatively and postoperatively on the 30th, 60th and 180th day. All of them received the same postoperative routine, including steroid drops.Results: Comparing with the preoperative values, there was a statistically significant increase in IOP on the 30th postoperative day, while there was a statistically significant decrease in IOP

  17. Ablation, surface activation, and electroless metallization of insulating materials by pulsed excimer laser irradiation

    International Nuclear Information System (INIS)

    Pulsed-laser irradiation of wide bandgap ceramic substrates, using photons with sub-bandgap energies, activates the ceramic surface for subsequent electroless copper deposition. The copper deposit is confined within the irradiated region when the substrate is subsequently immersed in an electroless copper bath. However, a high laser fluence (typically several j/cm2) and repeated laser shots are needed to obtain uniform copper coverage by this direct-irradiation process. In contrast, by first applying an evaporated SiOx thin film (with x ∼1), laser ablation at quite low energy density (∼0.5 J/cm2) results in re-deposition on the ceramic substrate of material that is catalytic for subsequent electroless copper deposition. Experiments indicate that the re-deposited material is on silicon, on which copper nucleates. Using an SiOx film on a laser-transparent substrate, quite fine (∼12 μm) copper lines can be formed at the boundary of the region that is laser-etched in SiOx. Using SiOx with an absorbing (polycrystalline) ceramic substrate, more-or-less uniform activation and subsequent copper deposition are obtained. In the later case, interactions with the ceramic substrate also may be important for uniform deposition

  18. Excimer Laser Deposition and Characterization of Cerium Doped TiO2

    Czech Academy of Sciences Publication Activity Database

    Fajgar, Radek; Dřínek, Vladislav; Kupčík, Jaroslav; Šubrt, Jan; Murafa, Nataliya

    - : -, 2011, s. 131. ISSN N. [EuroCVD 18. Kinsale, Co. Cork (IE), 04.09.2011-09.09.2011] Institutional research plan: CEZ:AV0Z40720504; CEZ:AV0Z40320502 Keywords : laser deposition * TiO2 * cerium Subject RIV: CH - Nuclear ; Quantum Chemistry

  19. Advances in Vitiligo Treatment by 308 nm Excimer Laser%308nm准分子激光治疗白癜风皮肤病进展

    Institute of Scientific and Technical Information of China (English)

    马跃; 杨春俊; 邓赞红; 林颖; 江海河; 方晓东

    2012-01-01

    临床研究表明波长308 nm准分子激光治疗白癜风皮肤病效果明显.治疗效果与病人的性别、年龄、病程没有明显关联,但与皮肤类型、皮损部位、治疗频度和疗程等有明显关联.在一定剂量范围内随治疗剂量和治疗时间增加治疗效果越来越明显,呈线性变化.而皮损部位的影响,疗效从明显到不明显的顺序是:面部,颈部和头皮,生殖器,四肢,躯干,手脚或肢端关节.皮肤类型对治疗效果影响明显.另外,在一定的观察时间内发现308 nm准分子激光疗效明显高于NB UVB.%This study is a retrospective review of the clinical efficacy of 308 nm excimer laser in vitiligo treatment. Clinical studies have reported that 308 nm excimer laser shows effective treatment of vitiligo. The treatment efficacy has showed no obvious correlation with the patients' sex, age and course of disease, but obviously correlated with skin type, skin lesions, treatment frequency and duration. The treatment efficacy increased linearly with the dose and duration of treatment in a certain dose range. The treatment response showed anatomical preferences, in a decline order of face, neck, scalp, genitals, limbs, trunk, extremities joints. Another factor on the efficacy was skin type. In addition, 308 nm excimer laser treatment appears to be more effective than NB UVB phototherapy in a certain observation period.

  20. Pulsed excimer laser deposited Co- and Fe-based magnetic films for fast magnetic sensors

    Czech Academy of Sciences Publication Activity Database

    Luby, S.; Majková, E.; Caricato, A. P.; Fernandez, M.; Luches, A.; Frait, Zdeněk; Fraitová, Dagmar; Malych, Rastislav

    272-276, - (2004), s. 1408-1409. ISSN 0304-8853 Grant ostatní: VEGA(SK) 1106/22; VEGA(SK) 2/3149/23; NATO(XX) PST .CLG.978058; HPRN-CT(XE) 1999-00150 Institutional research plan: CEZ:AV0Z1010914 Keywords : laser ablation * magnetic thin film * magnetization motion damping Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.031, year: 2004

  1. The study of metal-alloy targets and excimer laser deposition technology

    CERN Document Server

    Xu Hua; Tang Yong Jian; Wu Wei Dong; Zhang Ji Cheng

    2002-01-01

    Pulsed Laser Deposition (PLD) technology is described. Design and manufacture of the PLD installation is illustrated in detail. The Cu films and Cu/Fe multi-layers are produced by PLD method. The production of the Mg/Si films using magnetron sputtering method is investigated in detail. The percent of Si on Mg/Si film surface is measured by using conductivity method

  2. Pulsed Excimer (KrF) Laser Melting of Amorphous and Crystalline Silicon Layers

    OpenAIRE

    Walthuis, A.; Stritzker, B.; White, C. W.; J. Narayan; Aziz, Michael

    1985-01-01

    We have investigated depth of melting as a function of pulse energy density in amorphous and crystalline silicon layers. The melting threshold for KrF laser pulses (lambda=0.249 µm, tau=24×10−9 s) in amorphous (7660-Å-thick) and crystalline silicon layers were determined to be 0.16±0.02 and 0.75±0.05 J cm−2, respectively. The formation of fine- and large-polycrystalline regions was clearly identified in the amorphous silicon layers for energy densities below that needed for complete annealing...

  3. Some optical and electron microscope comparative studies of excimer laser-assisted and nonassisted molecular-beam epitaxically grown thin GaAs films on Si

    Science.gov (United States)

    Lao, Pudong; Tang, Wade C.; Rajkumar, K. C.; Guha, S.; Madhukar, A.; Liu, J. K.; Grunthaner, F. J.

    1990-01-01

    The quality of GaAs thin films grown via MBE under pulsed excimer laser irradiation on Si substrates is examined in both laser-irradiated and nonirradiated areas using Raman scattering, Rayleigh scattering, and by photoluminescence (PL), as a function of temperature, and by TEM. The temperature dependence of the PL and Raman peak positions indicates the presence of compressive stress in the thin GaAs films in both laser-irradiated and nonirradiated areas. This indicates incomplete homogeneous strain relaxation by dislocations at the growth temperature. The residual compressive strain at the growth temperature is large enough such that even with the introduction of tensile strain arising from the difference in thermal expansion coefficients of GaAs and Si, a compressive strain is still present at room temperature for these thin GaAs/Si films.

  4. Comparison of boron diffusion in silicon during shallow p{sup +}/n junction formation by non-melt excimer and green laser annealing

    Energy Technology Data Exchange (ETDEWEB)

    Aid, Siti Rahmah; Matsumoto, Satoru [Department of Electronics and Electrical Engineering, Keio University, 3-14-1 Hiyoshi, Kouhoku-ku, Yokohama, Kanagawa 223-8522 (Japan); Fuse, Genshu [SEN Corporation, SBS Tower 9F, 4-10-1 Yoga, Setagaya-ku, Tokyo 158-0097 (Japan); Sakuragi, Susumu [Sumitomo Heavy Industries Ltd., 19 Natsushima-cho, Yokosuka, Kanagawa 237-8555 (Japan)

    2011-12-15

    The combination of Ge pre-amorphization implantation, low-energy boron implantation, and non-melt laser annealing is a promising method for forming ultrashallow p{sup +}/n junctions in silicon. In this study, shallow p{sup +}/n junctions were formed by non-melt annealing implanted samples using a green laser (visible laser). The dopant diffusion, activation, and recrystallization of an amorphous silicon layer were compared with those obtained in our previous study in which non-melt annealing was performed using a KrF excimer laser (UV laser). The experimental results reveal that only slight diffusion of boron in the tail region occurred in green-laser-annealed samples. In contrast, remarkable boron diffusion occurred in KrF-laser-annealed samples for very short annealing times. Recrystallization of the amorphous silicon layer was slower in green-laser-annealed samples than in KrF-laser-annealed samples. We consider the penetration depth and the pulse duration are important factors that may affect boron diffusion. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. High-speed photography of plasma during excimer laser-tissue interaction

    Energy Technology Data Exchange (ETDEWEB)

    Murray, Andrea K; Dickinson, Mark R [Laser Photonics Group, Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester, M13 9PL (United Kingdom)

    2004-08-07

    During high fluence laser-tissue interaction, ablation of tissue occurs, debris is removed from the ablation site and is then ejected at high velocity. This debris may be observed as a combination of luminous plasma and non-luminous plume, both of which have the potential to shield the ablation site. This study examined the role of ablation debris in shielding the tissue and determined its effects on the ablation rate over a range of laser pulse energies, pulse repetition rates and pulse numbers for dentine; the velocity differences between hard and soft tissues were also examined. High-speed photography was carried out at up to 1 x 10{sup 8} frames per second. A maximum velocity of 2.58 {+-} 0.52 x 10{sup 4} m s{sup -1} was recorded for dentine debris within the first 10 ns following ejection. The maximum duration of tissue shielding due to a single pulse, determined by attenuation of a probe beam, was found to be {approx}7 ms, {approx}80 {mu}s of which was due to luminous plasma and the remainder due to the non-luminous plume.

  6. Efficacy of 308 nm excimer laser on vitiligo%308 nm 准分子激光治疗白癜风

    Institute of Scientific and Technical Information of China (English)

    王国学

    2015-01-01

    Objective To investigate the efficacy of 308 nm excimer laser on vitiligo. Methods From Aygyst 2010 to Octo-ber 2012,fifty six patients with vitiligo were selected and were given 308 nm excimer laser,twice a week and followed yp for 6 months,the effect was observed. Results After average 26. 3 times of local irradiation of excimer light,76. 5% had varying de-grees of repigmentation of lesions,pigmented recovered increases with prolonged treatment,irradiation of 45 times the total effi-ciency rate was 92. 6% . Torso,neck,head were better than the limbs,hands and feet,generalized and segmental vitiligo had a good effect. The main adverse reactions were local blisters and pain,and the patients coyld tolerate. Conclusion The effect of excimer laser on vitiligo is significantly and has fewer adverse reactions,and its efficacy is associated with lesions anatomy.%目的:探讨308 nm 准分子激光局部照射治疗白癜风的疗效。方法选择2010年8月至2012年10月收治的白癜风患者56例,给予308 nm 准分子激光局部照射,每周2次,随访6个月,观察其疗效。结果经过准分子光局部照射平均26.3次,76.5%皮损有不同程度色素恢复,色素恢复随疗程延长而增加,照射45次总有效率为92.6%。躯干、颈部、头部疗效优于四肢、手足,泛发型和节段型白癜风。主要不良反应为局部水疱和疼痛,患者能耐受。结论准分子光局部照射治疗白癜风疗效显著且不良反应少,其疗效与皮损解剖部位相关。

  7. Long-term efficacy of excimer laser in situ keratomileusis in the management of children with high anisometropic amblyopia

    Institute of Scientific and Technical Information of China (English)

    LIN Xiao-ming; YAN Xiao-he; WANG Zheng; YANG Bin; CHEN Qi-wen; SU Jin-ai; YE Xue-lian

    2009-01-01

    Background Children with anisometropic amblyopia are often noncompliant with traditional treatment including spectacules and contact lenses.This study was to evaluate the long-term efficacy of excimer laser in situ keratomileusis (LASIK) for children with high anisometropic amblyopia.Methods A retrospective analysis of 24 children with high unilateral anisometropic amblyopia,who underwent LASIK during the period between August 2000 and September 2005 in our hospital,was conducted.The mean age of these children was (7.4±1.9) years (range 5-14 years) and the mean follow-up period was (33.3±14.2) months (range 18.5-74.2 months).After LASIK,visual acuity,refraction and far or near stereoacuity were analyzed.Near stereoacuity was measured by the random-dot butterfly stereogram and the pre-school random-dot stereogram,while far stereoacuity was measured by the synoptophore with Yan's random-dot stereogram.Results Mean preoperative uncorrected visual acuity was 0.06±0.05,while mean postoperative uncorrected visual acuity was elevated to 0.43±0.33.Mean preoperative best-corrected visual acuity was 0.26±0.22,while mean postoperative best-corrected visual acuity was elevated to 0.67±0.40.For patients with myopic anisometropia,preoperative mean spherical equivalent refraction was (-8.01±2.70) D while postoperative value significantly reduced to (-1.32±2.47) D.For patients with hyperopic anisometropia,preoperative mean spherical equivalent refraction was (+7.35±1.55) D while postoperative value significantly reduced to (+3.30±0.86) D.These results demonstrated that there was statistical difference in these parameters between preoperative and postoperative tests.At the last follow-up,20 patients had near stereoacuity,and the mean near stereoacuities measured by the random-dot butterfly stereogram and the preschool random-dot stereogram were (149.00±152.93)" and (201.05±235.94)",respectively.In contrast,11 patients had far stereoacuity,and the mean far stereoacuity

  8. Effects of closed immersion filtered water flow velocity on the ablation threshold of bisphenol A polycarbonate during excimer laser machining

    International Nuclear Information System (INIS)

    A closed flowing thick film filtered water immersion technique ensures a controlled geometry for both the optical interfaces of the flowing liquid film and allows repeatable control of flow-rate during machining. This has the action of preventing splashing, ensures repeatable machining conditions and allows control of liquid flow velocity. To investigate the impact of this technique on ablation threshold, bisphenol A polycarbonate samples have been machined using KrF excimer laser radiation passing through a medium of filtered water flowing at a number of flow velocities, that are controllable by modifying the liquid flow-rates. An average decrease in ablation threshold of 7.5% when using turbulent flow velocity regime closed thick film filtered water immersed ablation, compared to ablation using a similar beam in ambient air; however, the use of laminar flow velocities resulted in negligible differences between closed flowing thick film filtered water immersion and ambient air. Plotting the recorded threshold fluence achieved with varying flow velocity showed that an optimum flow velocity of 3.00 m/s existed which yielded a minimum ablation threshold of 112 mJ/cm2. This is attributed to the distortion of the ablation plume effected by the flowing immersion fluid changing the ablation mechanism: at laminar flow velocities Bremsstrahlung attenuation decreases etch rate, at excessive flow velocities the plume is completely destroyed, removing the effect of plume etching. Laminar flow velocity regime ablation is limited by slow removal of debris causing a non-linear etch rate over 'n' pulses which is a result of debris produced by one pulse remaining suspended over the feature for the next pulse. The impact of closed thick film filtered water immersed ablation is dependant upon beam fluence: high fluence beams achieved greater etch efficiency at high flow velocities as the effect of Bremsstrahlung attenuation is removed by the action of the fluid on the plume; low

  9. Micromachining of Al2O3-TiC ceramics by excimer laser

    Directory of Open Access Journals (Sweden)

    Oliveira, V.

    1998-04-01

    Full Text Available Micromachining of Al2O3-TiC ceramic using a KrF excimer laser was studied in the fluence range 2 to 8 J/cm2 . The ablation rate decreases and the roughness increases with the first pulses but after about 200 pulses the process reaches a stationary stage where both roughness and ablation rate become constant. Observation of the processed areas by scanning electron microscopy showed that a globular topography is formed during the first stage and that the surface topography remains unchanged with further pulses. This globular topography is responsible for the variation of roughness and ablation rate observed during the first stage. EDS analysis showed that the globular features present an external region with higher titanium content and a core formed of unaffected material.

    Se estudia el micromecanizado de cerámicas Al2O3-TiC mediante un láser de excímero de KrF con un rango de fluencia de 2 a 8 J/cm2 . La velocidad de ablación disminuye y la rugosidad aumenta con los primeros pulsos. Sin embargo, después de 200 pulsos, el proceso alcanza el régimen estacionario, donde tanto la rugosidad como la velocidad de ablación permanecen constantes. La observación mediante SEM de determinadas áreas mostraban una topografía globular formada durante la primera etapa, mientras que con los siguientes pulsos permanece in cambios. Esta topografía globular es responsable de la variación de rugosidad y de la velocidad de ablación observada durante las primeras etapas del proceso. Los análisis de EDS sobre las zonas globulares mostraron la existencia de una región externa rica en titanio y un núcleo formado por el material sin afectar.

  10. Topography-guided hyperopic and hyperopic astigmatism femtosecond laser-assisted LASIK: long-term experience with the 400 Hz eye-Q excimer platform

    Directory of Open Access Journals (Sweden)

    Kanellopoulos AJ

    2012-06-01

    Full Text Available Anastasios John KanellopoulosDepartment of Ophthalmology, New York University Medical School, New York, NY, and LaserVision.gr Eye Institute, Athens, GreeceBackground: The purpose of this study was to evaluate the safety and efficacy of topography-guided ablation using the WaveLight 400 Hz excimer laser in laser-assisted in situ keratomileusis (LASIK for hyperopia and/or hyperopic astigmatism.Methods: We prospectively evaluated 208 consecutive LASIK cases for hyperopia with or without astigmatism using the topography-guided platform of the 400 Hz Eye-Q excimer system. The mean preoperative sphere value was +3.04 ± 1.75 (range 0.75–7.25 diopters (D and the mean cylinder value was –1.24 ± 1.41 (–4.75–0 D. Flaps were created either with Intralase FS60 (AMO, Irvine, CA or FS200 (Alcon, Fort Worth, TX femtosecond lasers. Parameters evaluated included age, preoperative and postoperative refractive error, uncorrected distance visual acuity, corrected distance visual acuity, flap diameter and thickness, topographic changes, higher order aberration changes, and low contrast sensitivity. These measurements were repeated postoperatively at regular intervals for at least 24 months.Results: Two hundred and two eyes were available for follow-up at 24 months. Uncorrected distance visual acuity improved from 5.5/10 to 9.2/10. At 24 (8–37 months, 75.5% of the eyes were in the ±0.50 D range and 94.4% were in the ±1.00 D range of the refractive goal. Postoperatively, the mean sphere value was –0.39 ± 0.3 and the cylinder value was –0.35 ± 0.25. Topographic evidence showed that ablation was made in the visual axis and not in the center of the cornea, thus correlating with the angle kappa. No significant complications were encountered in this small group of patients.Conclusion: Hyperopic LASIK utilizing the topography-guided platform of the 400 Hz Eye-Q Allegretto excimer and a femtosecond laser flap appears to be safe and effective for

  11. 10 x 10 cm-sq aperture 1 Hz repetition rate X-ray preionized-discharge pumped KrF excimer laser

    Science.gov (United States)

    Mizoguchi, H.; Endoh, A.; Jethwa, J.; Schaefer, F. P.

    A 10 x 10 sq cm aperture X-ray preionized discharge-pumped KrF excimer amplifier for subpicosecond pulse amplification is demonstrated experimentally in the oscillator mode operation. A fast pulse-forming line (36 nF, 340 kV) together with a peaking capacitor (6 nF) switched with a rail-gap switch, and collimated X-ray preionization is employed to obtain a wide and uniform discharge. The active cross section of the laser beam is about 10 x 8 sq cm and the intense plateau region is about 10 x 5.5 sq cm. The laser pulse energy exceeds 4.7 J in a 28 ns pulse (FWHM).

  12. Fabrication of an integrated optical Mach-Zehnder interferometer based on refractive index modification of polymethylmethacrylate by krypton fluoride excimer laser radiation

    International Nuclear Information System (INIS)

    It is known that deep ultraviolet (UV) radiation induces a refractive index increase in the surface layer of polymethylmethacrylate (PMMA) samples. This effect can be used for the fabrication of integrated optical waveguides. PMMA is of considerable interest for bio and chemical sensing applications because it is biocompatible and can be micromachined by several methods, e.g. structuring by photolithography, ablation and hot embossing. In the presented work direct UV irradiation of a common PMMA substrate by a krypton fluoride excimer laser beam through a contact mask has been used to write integrated optical Mach-Zehnder interferometers (MZI). MZI are used as sensitive bio and chemical sensors. The aim was to determine contact mask design and laser irradiation parameters for fabricating single-mode MZI for the infrared region from 1.30 μm to 1.62 μm. Straight and curved waveguides have been generated and characterized to determine the optical losses. The generation of channel waveguide structures has been optimized by a two step irradiation process to minimize the lithographic writing time and optical loss. By flood exposure to UV laser radiation in the first step the optical absorption of PMMA can be increased in the irradiated region. The required refractive index profile is then achieved with a second lithographic irradiation. The spectral behaviour of an unbalanced, integrated optical MZI fabricated by this excimer laser based contact mask method is shown for the first time. Further the optical intensity at the output port of a MZI has been measured while the optical path length difference was tuned by creating a temperature difference between the two arms of the MZI.

  13. Synthesis of diamond on WC-Co substrates using a KrF excimer laser in combination with a combustion flame

    Science.gov (United States)

    Han, Y. X.; Ling, H.; Lu, Y. F.

    2007-02-01

    A KrF excimer laser was used in combination with a combustion flame to deposit diamond films on cemented tungsten carbide (WC-Co) substrates. The laser has a wavelength of 248 nm, a pulse width of 23 ns, a pulse energy range of 84~450 mJ, and a repetition rate up to 50 Hz. Using the combustion flame method, diamond films were deposited on the laser-processed WC-Co substrates for 10 min. The morphologies of the deposited diamond films were examined using a scanning electron microscopy (SEM). The composition and bonding structures in the deposited films were studied by energy dispersive X-ray analysis (EDX) and Raman spectroscopy, respectively. The film adhesion was characterized by scratching a razor across the films. It was found that C composition on WC-Co substrate surfaces was eliminated by the laser irradiation. As a consequence, diamond nucleation density decreased and diamond grains grew larger in the laser-processed areas. Based on the experimental results, a film growth mechanism at different deposition temperature ranges corresponding to pre-deposition laser-surface-treatment effects was proposed.

  14. Manufacturing of Er:ZBLAN ridge waveguides by pulsed laser deposition and ultrafast laser micromachining for green integrated lasers

    Energy Technology Data Exchange (ETDEWEB)

    Gottmann, Jens [Lehrstuhl fuer Lasertechnik, RWTH Aachen University, Steinbachstr. 15, 52074 Aachen (Germany)], E-mail: jens.gottmann@llt.rwth-aachen.de; Moiseev, Leonid; Vasilief, Ion; Wortmann, Dirk [Lehrstuhl fuer Lasertechnik, RWTH Aachen University, Steinbachstr. 15, 52074 Aachen (Germany)

    2008-01-15

    Laser radiation is used both for the deposition of the laser active thin films and for the microstructuring to define wave guiding structures for the fabrication of waveguide lasers. Thin films of Er:ZBLAN (a fluoride glass consisting of ZrF{sub 4}, BaF{sub 2}, LaF{sub 3}, AlF{sub 3}, NaF, ErF{sub 3}) for green up-conversion lasers (545 nm) are produced by pulsed laser deposition using ArF excimer laser radiation (wavelength 193 nm). Manufacturing of the laser active waveguides by microstructuring is done using fs-laser ablation of the deposited films. The structural and optical properties of the films and the damping losses of the structured waveguides are determined in view of the design and the fabrication of compact and efficient diode pumped waveguide lasers. The resulting waveguides are polished, provided with resonator mirrors, pumped using diode lasers and characterized.

  15. Laser assisted modification and chemical metallization of electron-beam deposited ceria thin films

    International Nuclear Information System (INIS)

    Excimer laser processing is applied for tailoring the surface morphology and phase composition of CeO2 ceramic thin films. E-beam evaporation technique is used to deposit samples on stainless steel and silicate glass substrates. The films are then irradiated with ArF* excimer laser pulses under different exposure conditions. Scanning electron microscopy, optical spectrophotometry, X-ray diffractometry and EDS microanalysis are used to characterize the non-irradiated and laser-processed films. Upon UV laser exposure there is large increase of the surface roughness that is accompanied by photo-darkening and ceria reduction. It is shown that the laser induced changes in the CeO2 films facilitate the deposition of metal nano-aggregates in a commercial copper electroless plating bath. The significance of laser modification as a novel approach for the production of CeO2 based thin film catalysts is discussed.

  16. Transformation of medical grade silicone rubber under Nd:YAG and excimer laser irradiation: First step towards a new miniaturized nerve electrode fabrication process

    Energy Technology Data Exchange (ETDEWEB)

    Dupas-Bruzek, C., E-mail: catherine.dupas@univ-lille1.fr [Universite des Sciences et Technologies de Lille (USTL), 59655 Villeneuve d' Ascq (France); Laboratoire de Physique des Lasers, Atomes et Molecules (PhLAM), UMR CNRS 8523, Centre d' Etudes et de Recherches Lasers et Applications (CERLA), FR CNRS 2416 (France); Robbe, O. [Universite des Sciences et Technologies de Lille (USTL), 59655 Villeneuve d' Ascq (France); Laboratoire de Spectroscopie Infrarouge et Raman (LASIR), UMR CNRS 8516, Centre d' Etudes et de Recherches Lasers et Applications (CERLA), FR CNRS 2416 (France); Addad, A. [Universite des Sciences et Technologies de Lille (USTL), 59655 Villeneuve d' Ascq (France); Laboratoire de Structures et Proprietes de l' Etat Solide (LSPES), UMR CNRS 8008 (France); Turrell, S. [Universite des Sciences et Technologies de Lille (USTL), 59655 Villeneuve d' Ascq (France); Laboratoire de Spectroscopie Infrarouge et Raman (LASIR), UMR CNRS 8516, Centre d' Etudes et de Recherches Lasers et Applications (CERLA), FR CNRS 2416 (France); Derozier, D. [Universite des Sciences et Technologies de Lille (USTL), 59655 Villeneuve d' Ascq (France); Laboratoire de Physique des Lasers, Atomes et Molecules (PhLAM), UMR CNRS 8523, Centre d' Etudes et de Recherches Lasers et Applications (CERLA), FR CNRS 2416 (France)

    2009-08-15

    Medical grade silicone rubber, poly-dimethylsiloxane (PDMS) is a widely used biomaterial. Like for many polymers, its surface can be modified in order to change one or several of its properties which further allow this surface to be functionalized. Laser-induced surface modification of PDMS under ambient conditions is an easy and powerful method for the surface modification of PDMS without altering its bulk properties. In particular, we profit from both UV laser inducing surface modification and of UV laser micromachining to develop a first part of a new process aiming at increasing the number of contacts and tracks within the same electrode surface to improve the nerve selectivity of implantable self sizing spiral cuff electrodes. The second and last part of the process is to further immerse the engraved electrode in an autocatalytic Pt bath leading in a selective Pt metallization of the laser irradiated tracks and contacts and thus to a functionalized PDMS surface. In the present work, we describe the different physical and chemical transformations of a medical grade PDMS as a function of the UV laser and of the irradiation conditions used. We show that the ablation depths, chemical composition, structure and morphology vary with (i) the laser wavelength (using an excimer laser at 248 nm and a frequency-quadrupled Nd:YAG laser at 266 nm), (ii) the conditions of irradiation and (iii) the pulse duration. These different modified properties are expected to have a strong influence on the nucleation and growth rates of platinum which govern the adhesion and the thickness of the Pt layer on the electrodes and thus the DC resistance of tracks.

  17. Transformation of medical grade silicone rubber under Nd:YAG and excimer laser irradiation: First step towards a new miniaturized nerve electrode fabrication process

    International Nuclear Information System (INIS)

    Medical grade silicone rubber, poly-dimethylsiloxane (PDMS) is a widely used biomaterial. Like for many polymers, its surface can be modified in order to change one or several of its properties which further allow this surface to be functionalized. Laser-induced surface modification of PDMS under ambient conditions is an easy and powerful method for the surface modification of PDMS without altering its bulk properties. In particular, we profit from both UV laser inducing surface modification and of UV laser micromachining to develop a first part of a new process aiming at increasing the number of contacts and tracks within the same electrode surface to improve the nerve selectivity of implantable self sizing spiral cuff electrodes. The second and last part of the process is to further immerse the engraved electrode in an autocatalytic Pt bath leading in a selective Pt metallization of the laser irradiated tracks and contacts and thus to a functionalized PDMS surface. In the present work, we describe the different physical and chemical transformations of a medical grade PDMS as a function of the UV laser and of the irradiation conditions used. We show that the ablation depths, chemical composition, structure and morphology vary with (i) the laser wavelength (using an excimer laser at 248 nm and a frequency-quadrupled Nd:YAG laser at 266 nm), (ii) the conditions of irradiation and (iii) the pulse duration. These different modified properties are expected to have a strong influence on the nucleation and growth rates of platinum which govern the adhesion and the thickness of the Pt layer on the electrodes and thus the DC resistance of tracks.

  18. 308 nm准分子光联合他克莫司软膏治疗白癜风临床观察%Cinical observation of the combination therapy of 308 nm excimer laser and tacrolimus on vitiligo

    Institute of Scientific and Technical Information of China (English)

    毕晓东

    2013-01-01

    目的 观察308 nm准分子光联合他克莫司治疗白癜风的临床疗效.方法 360例白癜风患者随机分为联合组和308单频光组,两组均采用准分子光系统进行308 nm光疗,联合组同时外用他克莫司软膏.结果 联合组和308单频光组的有效率分别为83.9%和和70.1%,差异具有统计学意义(P<0.05).两组临床有效率最高的部位均为颈部、面部和躯干,最低为手足部;稳定期疗效高于进展期,差异均具有统计学意义(P<0.05).结论 308 nm准分子光联合外用他克莫司软膏治疗白癜风临床疗效好.%Objective To observe the clinical effect of the combination therapy of 308nm excimer laser and tacrolimus on vitiligo. Methods Three hundreds and sixty cases with vitiligo were randomly divided into combination therapy group and 308nm excimer laser group. The cases were all treated with 308nm excimer laser, and the combination therapy group was given tacrolimus ointment additionally. Results The total effective rate of combination therapy group was 83.9%, higher than 70.1% of 308nm excimer laser group (P<0.05). In the both groups the positions showed the highes total effective rate were neck, face and trunk, and the lowest were hands and feet. The curative effect in stable stage was better than that in progressive stage (P<0.05). Conclusion The combination trerapy of tacmlimus ointment and the 308nm excimer laser is superior to 308nm excimer laser monotherapy for the treatment of vitiligo.

  19. Comparison of outcomes of conventional WaveLight® Allegretto Wave® and Technolas® excimer lasers in myopic laser in situ keratomileusis

    Directory of Open Access Journals (Sweden)

    Han DC

    2012-07-01

    Full Text Available Daphne CY Han,1,2 Jean Chen,3 Hla Myint Htoon,2 Donald TH Tan,1,2,4 Jodhbir S Mehta1,21Singapore National Eye Centre, 2Singapore Eye Research Institute, 3Yong Loo Lin School of Medicine, National University of Singapore, 4Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, SingaporeObjective: To compare the results of laser in situ keratomileusis for myopia using WaveLight® Allegretto Wave® Eye-Q® and Technolas® 217z excimer lasers.Method: A retrospective, comparative case series of 442 eyes matched for age and myopia: half each were treated with Allegretto's wavefront-optimized algorithm and Technolas PlanoScan. Outcome measures were postoperative mean logarithm of the minimum angle of resolution (logMAR uncorrected visual acuity (UCVA, manifest refraction spherical equivalent (MRSE, cylinder, safety and efficacy indices, refractive predictability, and optical zone size selection. Refractive predictability of a subgroup treated for –2.50 to –4.0 diopter (D was analyzed separately.Results: At mean follow-up of 80.5 days, mean logMAR UCVA, mean MRSE and mean postoperative cylinder were 0.02 ± 0.07 (range –0.12 to 0.30, 0.27 ± 0.36 D (range –1.25 to 1.50 D and –0.33 ± 0.30 D (range 0.00 to –1.50 D for Allegretto versus 0.02 ± 0.08 (range –0.12 to 0.40, 0.095 ± 0.47 D (range –1.25 to 1.13 D and –0.44 ± 0.5 2 D (range 0.00 to –2.25 D for Technolas (P = 0.98, 0.80 and 0.006. Mean safety and efficacy indices were 1.05 ± 0.13 (0.75–1.33 and 0.97 ± 0.13 (0.50–1.33 for Allegretto and 1.07 ± 0.14 (0.75–1.49 and 0.97 ± 0.17 (0.40–1.49 for Technolas (P = 0.23 and 0.69. Proportions of eyes achieving postoperative MRSE within ±1.0 D, ±0.5 D, and ±0.25 D were 98.2%, 91.9% and 75.6% for Allegretto and 99.1%, 97.8% and 72.4% for Technolas (P = 0.68, 0.20 and 0.51. Mean optical zone size selected was 6.48 ± 0.10 mm (range 6.0–6.5 mm for Allegretto and 6.38 ± 0.19 mm

  20. Self-assembly of a new type of periodic surface structure in a copolymer by excimer laser irradiation above the ablation threshold

    Energy Technology Data Exchange (ETDEWEB)

    Dorronsoro, Carlos; Siegel, Jan [Instituto de Optica, CSIC, Serrano 121, 28006 Madrid (Spain); Bonse, Jörn [BAM Bundesanstalt für Materialforschung und–prüfung, Unter den Eichen 87, 12205 Berlin (Germany)

    2013-10-21

    We report self-assembly of periodic surface structures in a commercial block copolymer (BCP) (Filofocon A) upon irradiation with a few tens of excimer laser pulses (20 ns, 193 nm) at fluences above the ablation threshold. This new type of structures is characterized by much larger periods than those characteristic for Laser-Induced Periodic Surface Structures (LIPSS) and features nanochains instead of ripples. We find a period of 790 nm at 400 mJ/cm{sup 2}, scaling linearly with laser fluence up to a maximum of 1.0 μm. While an entangled random network of nanochains is produced for normal-incidence and non-polarized light, nanochain alignment can be achieved either by irradiation at an angle or by using linearly polarized light, forming a lamella-like structure. In both cases, the nanochains are aligned parallel to the penetrating polarization orientation and their period does not show a dependence on the angle of incidence, as opposed to the general behavior of standard LIPSS. Also, our results show that the chains are not formed by frozen capillary waves. In contrast, we show analogies of the nanochains produced to lamellar structures fabricated on a smaller scale in other BCP. We discuss the origin of the self-assembly process in terms of a combination of chemical (BCP), optical (surface scattering), and thermal (melting, coarsening, and ablation) effects.

  1. Ultra-shallow junction formation by excimer laser annealing and low energy (<1 keV) B implantation: A two-dimensional analysis

    International Nuclear Information System (INIS)

    Formation of shallow junctions has been investigated by using excimer laser annealing in combination with two implantation schemes: BF2-ions at 20 keV and B-ions at low energies (<1 keV). The latter approach was shown to produce best results, with ultra-shallow profiles extending to a depth as low as 35 nm. The lateral distribution of the implanted B following laser annealing has been studied with two-dimensional measurements using selective etching and cross-section transmission electron microscopy (TEM) on samples where the implanted dopant was confined within an oxide mask. The results show that there is substantial lateral diffusion of B under the oxide mask when melting occurs in this region while, if melting under the oxide mask is prevented, the implanted B close to the oxide mask edge was not activated by laser annealing. The results have been explained by numerical heat-flow calculations and it is concluded that the melting of the Si under the masked region and, therefore, the lateral diffusion, can be controlled by the oxide mask thickness

  2. Self-assembly of a new type of periodic surface structure in a copolymer by excimer laser irradiation above the ablation threshold

    International Nuclear Information System (INIS)

    We report self-assembly of periodic surface structures in a commercial block copolymer (BCP) (Filofocon A) upon irradiation with a few tens of excimer laser pulses (20 ns, 193 nm) at fluences above the ablation threshold. This new type of structures is characterized by much larger periods than those characteristic for Laser-Induced Periodic Surface Structures (LIPSS) and features nanochains instead of ripples. We find a period of 790 nm at 400 mJ/cm2, scaling linearly with laser fluence up to a maximum of 1.0 μm. While an entangled random network of nanochains is produced for normal-incidence and non-polarized light, nanochain alignment can be achieved either by irradiation at an angle or by using linearly polarized light, forming a lamella-like structure. In both cases, the nanochains are aligned parallel to the penetrating polarization orientation and their period does not show a dependence on the angle of incidence, as opposed to the general behavior of standard LIPSS. Also, our results show that the chains are not formed by frozen capillary waves. In contrast, we show analogies of the nanochains produced to lamellar structures fabricated on a smaller scale in other BCP. We discuss the origin of the self-assembly process in terms of a combination of chemical (BCP), optical (surface scattering), and thermal (melting, coarsening, and ablation) effects

  3. F2 excimer laser (157 nm) radiation modification and surface ablation of PHEMA hydrogels and the effects on bioactivity: Surface attachment and proliferation of human corneal epithelial cells

    International Nuclear Information System (INIS)

    Physical and chemical changes at the surface of poly(2-hydroxyethyl methacrylate) (PHEMA) hydrogels modified by ablation with an F2 excimer laser were investigated experimentally. An important observation was that only the outer exposed surface layers of the hydrogel were affected by the exposure to 157 nm radiation. The effect of the surface changes on the tendency of cells to adhere to the PHEMA was also investigated. A 0.5 cm2 area of the hydrogel surfaces was exposed to laser irradiation at 157 nm to fluences of 0.8 and 4 J cm-2. The changes in surface topography were analysed by light microscopy and atomic force microscopy, while the surface chemistry was characterized by attenuated total reflection infrared and X-ray photoelectron spectroscopies. Cell-interfacial interactions were examined based on the proliferation of human corneal limbal epithelial (HLE) cells cultured on the laser-modified hydrogels, and on the unexposed hydrogels and tissue culture plastic for comparison. It was observed that the surface topography of laser-exposed hydrogels showed rippled patterns with a surface roughness increasing at the higher exposure dose. The changes in surface chemistry were affected not only by an indirect effect of hydrogen and hydroxyl radicals, formed by water photolysis, on the PHEMA, but also by the direct action of laser radiation on PHEMA if the surface layers of the gel become depleted of water. The laser treatment led to a change in the surface characteristics, with a lower concentration of ester side-chains and the formation of new oxygenated species at the surface. The surface also became more hydrophobic. Most importantly, the surface chemistry and the newly created surface topographical features were able to improve the attachment, spreading and growth of HLE cells.

  4. 高功率准分子激光系统光学设计%Optical design of high power excimer laser system

    Institute of Scientific and Technical Information of China (English)

    张永生; 赵军; 马连英; 易爱平; 刘晶儒

    2011-01-01

    Image relay and angular multiplexing, which should be considered together in the design of high power excimer laser system, is reviewed. It's important to select proper illumination setup and laser beam shaping techniques. Given the com-plex and special angular multiplexing scheme in high power excimer laser systems, some detailed conceptual layout schemes are given in the paper. After a brief description of lens array and reflective telescope objective, which combine the incoming beams to a common focus, a new schematic layout which uses the final targeting optics and one optical delay line array, to realize multiple-xing and de-multiplexing simultaneously is first proposed in the paper.%回顾并介绍了高功率准分子激光系统设计中需要综合考虑的两项主要技术——像传递技术和角多路技术.讨论了照明方式和激光振荡源的光束整形在激光系统成像光路设计中的重要作用,对多路放大技术及角多路放大技术形式进行了系统分析.多路激光非相干合束是角多路技术和成像技术对高功率准分子激光系统光学设计提出的特殊要求,在简要分析了透射阵列和反射式望远物镜两种实现多路激光合束的打靶光学系统基础上,提出了一种利用反射式打靶光学系统和一套光学延迟线阵列来同时实现角多路编码和解码的新型光路布局,给出了初步设计方案.

  5. O impacto da cirurgia de ceratectomia fotorrefrativa (PRK e ceratomileuse assistida por excimer laser in situ (LASIK na qualidade visual e de vida em pacientes com ametropias The impact of photorefractive excimer laser keratectomy (PRK and laser in situ keratomileusis (LASIK on visual quality and life in patients with ametropias

    Directory of Open Access Journals (Sweden)

    Ricardo Belfort

    2008-02-01

    Full Text Available OBJETIVO: Avaliar a qualidade de vida e de visão e o estresse de pacientes portadores de ametropias submetidos a procedimentos cirúrgicos. MÉTODOS: Estudo longitudinal observacional em que foram estudados 100 pacientes; 54 usuários de óculos, 21 usuários de lentes de contato interessados no procedimento cirúrgico e 25 controles usuários de óculos ou lentes de contato, mas que não desejavam ser operados no período de um ano. Os questionários aplicados foram o National Eye Institute Visual Function Questionnaire (NEI-VFQ-25 de qualidade de vida e o Self Reporting Questionnaire - SRQ-20 para avaliação da saúde mental. Os pacientes que se submeteram à cirurgia responderam aos questionários aplicados por uma observadora antes da mesma, três, seis e doze meses após a intervenção. O grupo controle respondeu de forma auto-aplicada no início do estudo, seis e doze meses após a primeira avaliação. RESULTADOS: No grupo da cirugia dos 54 pacientes que usavam óculos 39 fizeram cirurgia de ceratectomia fotorrefrativa por excimer laser(PRK e 15 fizeram ceratomileuse assistida por excimer laserin situ (LASIK e dos 21 que usavam lentes de contato 12 fizeram cirurgia de ceratectomia fotorrefrativa e nove fizeram ceratomileuse assistida por excimer laser in situ (LASIK. O grupo controle esteve estável durante os 12 meses em relação aos instrumentos aplicados. Três meses após a cirurgia o grupo da cirurgia apresentou melhora significante da qualidade de vida e de visão em relação ao pré-operatório independentemente do tipo de cirurgia realizada. Um ano após a cirurgia os índices de qualidade de vida e de saúde mental, foram semelhantes aos do grupo controle. O Self Reporting Questionnaire - SRQ 20 mostrou diminuição significante do índice de sintomas a partir dos três meses de pós-operatório. CONCLUSÃO: A qualidade de visão e de vida dos pacientes submetidos à cirurgia de correção de ametropia mudou

  6. Necessary conditions for the homogeneous formation of a volume avalanche discharge with specific applications to rare gas-halide excimer laser discharges

    International Nuclear Information System (INIS)

    Self-sustained/avalanche discharges are an efficient method of rare gas-halide excimer laser excitation in small systems. However, with the exceptions of the work reported here, experiments attempting to increase the laser energy output by scaling up the discharge volume and/or pulse duration have not been successful. The major problem encountered in scaling experiments has been the formation of arc channels in the discharge volume. The presence of arcing can totally disrupt proper laser operation. This problem stems from a general lack of understanding of high pressure avalanche discharge phenomena. Therefore, clarifying the basic discharge formation process and establishing a set of criteria under which a homogeneous avalanche discharge can be obtained is of central importance in defining the scaling limits of avalanche discharge lasers. The work presented here reviews the phenomena involved in high E/n (electric field to gas number density ratio) breakdown and its relationship to the formation of spatially homogeneous discharges. This relationship was first explored by A.J. Palmer in 1974. The basic requirement of his model was that the preionization density be large enough to cause an appreciable overlap of the primary electron avalanches and hence smooth out the ensuing space-charge fields to the extent that individual streamer formation would be prevented. This is the same basic model used in the more detailed discharge formation analysis developed here except that the effects of a time varying electric field caused by a finite voltage rise time and the effects due to the various electrochemical properties of the gas mixture are property taken into consideration

  7. p-i-n CdTe multi-pixel detector for gamma-ray imaging fabricated by excimer laser processing

    International Nuclear Information System (INIS)

    A multi-pixel gamma-ray imaging detector unit, which has a high-energy resolution with room temperature operation, was fabricated using the diode-type CdTe detector. The diode structure was prepared by indium-doped n-type CdTe thin layer formed by excimer laser doping on one-side of high resistivity p-like single crystal CdTe wafer, and a gold electrode as a Shottkey electrode evaporated on the opposite side of the wafer. This diode-detectors showed good diode I-V characteristics with low leakage current. This CdTe detectors were pixelized in the 2mm x 2mm, and the 128 chips (32x4 chips) were mounted on the ceramic printed circuit boards at 3 mm interval with 1 mm gap. The printed circuit boards are directly connected the MCSA-EXI ASIC chip and 128 ch radiation spectrum analyzer systems. When using the Am-241 and the Co-57 as radioisotopes, the spectral response from all the pixels within 4,4 ke V of FWHM at 122 ke V peak of Co-57 for radiation performed at room temperature. The intensities of the peak from pixels were also uniform (Authors)

  8. Nano-crystallization in ZnO-doped In2O3 thin films via excimer laser annealing for thin-film transistors

    Science.gov (United States)

    Fujii, Mami N.; Ishikawa, Yasuaki; Ishihara, Ryoichi; van der Cingel, Johan; Mofrad, Mohammad R. T.; Bermundo, Juan Paolo Soria; Kawashima, Emi; Tomai, Shigekazu; Yano, Koki; Uraoka, Yukiharu

    2016-06-01

    In a previous work, we reported the high field effect mobility of ZnO-doped In2O3 (IZO) thin film transistors (TFTs) irradiated by excimer laser annealing (ELA) [M. Fujii et al., Appl. Phys. Lett. 102, 122107 (2013)]. However, a deeper understanding of the effect of ELA on the IZO film characteristics based on crystallinity, carrier concentrations, and optical properties is needed to control localized carrier concentrations for fabricating self-aligned structures in the same oxide film and to adequately explain the physical characteristics. In the case of as-deposited IZO film used as the channel, a high carrier concentration due to a high density of oxygen vacancies was observed; such a film does not show the required TFT characteristics but can act as a conductive film. We achieved a decrease in the carrier concentration of IZO films by crystallization using ELA. This means that ELA can form localized conductive or semi-conductive areas on the IZO film. We confirmed that the reason for the carrier concentration decrease was the decrease of oxygen-deficient regions and film crystallization. The annealed IZO films showed nano-crystalline phase, and the temperature at the substrate was substantially less than the temperature limit for flexible films such as plastic, which is 50°C. This paves the way for the formation of self-aligned structures and separately formed conductive and semi-conductive regions in the same oxide film.

  9. Comparison of Immediate and 2-Year Outcomes between Excimer Laser-Assisted Angioplasty with Spot Stent and Primary Stenting in Intermediate to Long Femoropopliteal Disease

    Directory of Open Access Journals (Sweden)

    Tien-Yu Wu

    2013-01-01

    Full Text Available Background. To compare the clinical outcomes between excimer laser-assisted angioplasty (ELA with spot stent (group A and primary stenting (group B in intermediate to long femoropopliteal disease. Methods. Outcomes of 105 patients totaling 119 legs treated with two different strategies were analyzed retrospectively in a prospectively maintained database. Results. Baseline characteristics were similar in both groups. Better angiographic results and lesser increase of serum C-reactive protein levels (0.60 ± 0.72 versus 2.98 ± 0.97 mg/dL, P<0.001 after the intervention were obtained in Group B. Group A had inferior 1-year outcomes due to higher rate of binary restenosis (67% versus 32%, P=0.001 and lower rate of primary patency (40% versus 58%, P=0.039. Rates of amputation-free survival, target vessel revascularization, assisted primary patency, and stent fracture at 24 months were similar in both groups (80% versus 82%, P=0.979, 65% versus 45%, P=0.11, 78% versus 80%, P=0.75 and 6.3% versus 6.8%, P=0.71, resp.. Conclusion. Greater vascular inflammation after ELA with spot stent resulted in earlier restenosis and inferior 1-year clinical outcomes than primary stenting. This benefit was lost in the primary stenting group at 2 years due to late catch-up restenosis. Active surveillance with prompt intervention was required to maintain the vessel patency.

  10. Pulsed Laser Deposition of Er doped tellurite films on large area

    Energy Technology Data Exchange (ETDEWEB)

    Bouazaoui, M [Laboratoire PhLAM, UMR 8523, Groupe Photonique, Universite des Sciences et Technologies de Lille, 59655 Villeneuve d' Ascq Cedex (France); Capoen, B [Laboratoire PhLAM, UMR 8523, Groupe Photonique, Universite des Sciences et Technologies de Lille, 59655 Villeneuve d' Ascq Cedex (France); Caricato, A P [L3 group, Dipartimento di Fisica, Lecce, Via Arnesano, 73100 Lecce (Italy); Chiasera, A [CNR-IFN, CSMFO group, via Sommarive 14, 38100 Povo-Trento (Italy); Fazzi, A [L3 group, Dipartimento di Fisica, Lecce, Via Arnesano, 73100 Lecce (Italy); Ferrari, M [CNR-IFN, CSMFO group, via Sommarive 14, 38100 Povo-Trento (Italy); Leggieri, G [L3 group, Dipartimento di Fisica, Lecce, Via Arnesano, 73100 Lecce (Italy); Martino, M [L3 group, Dipartimento di Fisica, Lecce, Via Arnesano, 73100 Lecce (Italy); Mattarelli, M [Physics Department, CSMFO group, via Sommarive 14, 38100 Povo-Trento (Italy); Montagna, M [Physics Department, CSMFO group, via Sommarive 14, 38100 Povo-Trento (Italy); Romano, F [L3 group, Dipartimento di Fisica, Lecce, Via Arnesano, 73100 Lecce (Italy); Tunno, T [L3 group, Dipartimento di Fisica, Lecce, Via Arnesano, 73100 Lecce (Italy); Turrel, S [Universite des Sciences et Technologies de Lille, Laboratoire de Spectrochimie Infrarouge et Raman, LASIR - UMR 8516 du CNRS - Bat C5 - 59655 - Villeneuve d' Ascq cedex (France); Vishnubhatla, K [Physics Department, CSMFO group, via Sommarive 14, 38100 Povo-Trento (Italy)

    2007-04-15

    Thin films of Er{sup 3+}-doped tungsten tellurite glass have been prepared by the pulsed laser deposition technique using an ArF excimer laser. The depositions were performed at different O{sub 2} pressure (5, 10 Pa) and at different substrate temperatures (RT, 100deg. C and 200deg. C). The composition and the optical properties of the deposited films, such as transmission, dispersion curves of refraction index and extinction coefficient, and film thickness were studied for the different deposition parameters. Transparent films at the highest substrate temperature were obtained only for a higher oxygen pressure with respect to the RT conditions.

  11. Excimer laser-induced material modification to create nanometer high smooth patterns in glass using mask projection

    Energy Technology Data Exchange (ETDEWEB)

    Rudolph, Thomas; Zimmer, Klaus; Boehme, Rico; Ruthe, David [Leibniz-Institut fuer Oberflaechenmodifizierung e.V., Permoserstrasse 15, D-04318 Leipzig (Germany)

    2007-04-15

    Laser swelling of borosilicate and soda-lime glass is shown for wavelengths of 193 and 248 nm. Very smooth patterns up to 45 nm high were generated by KrF laser (248 nm) irradiation of borosilicate glass at a fluence of 1.5 J/cm{sup 2}. At 193 nm laser wavelength, lower heights (up to 13 nm) and lower swelling threshold fluences (0.1 J/cm{sup 2}) were observed due to higher material absorption. For the less absorbing soda-lime glass higher fluences than for the borosilicate glass are needed to establish elevated structures. Gratings in borosilicate glass with sub-micron periodicity demonstrate the high resolution of the method. The results can be explained by a thermo-physical model based on the change of the glass transition temperature due to fast cooling after the pulsed laser irradiation.

  12. SBS pulse compression for excimer inertial fusion energy drivers

    International Nuclear Information System (INIS)

    A key requirement for the development of commercial fusion power plants utilizing inertial confinement fusion (ICF) as a source of thermonuclear power is the availability of reliable, efficient laser drivers. These laser drivers must be capable of delivering UV optical pulses having energies of the order of 5MJ to cryogenic deuterium-tritium (D/T) ICF targets. The current requirements for laser ICF target irradiation specify the laser wavelength, λ ca. 250 nm, pulse duration, τp ca. 6 ns, bandwidth, Δλ ca. 0.1 nm, polarization state, etc. Excimer lasers are a leading candidate to fill these demanding ICF driver requirements. However, since excimer lasers are not storage lasers, the excimer laser pulse duration, τpp, is determined primarily by the length of the excitation pulse delivered to the excimer laser amplifier. Pulsed power associated with efficiently generating excimer laser pulses has a time constant, τpp which falls in the range, 30 τpppp. As a consequence, pulse compression is needed to convert the long excimer laser pulses to pulses of duration τp. These main ICF driver pulses require, in addition, longer, lower power precursor pulses delivered to the ICF target before the arrival of the main pulse. Although both linear and non-linear optical (NLO) pulse compression techniques have been developed, computer simulations have shown that a ''chirped,'' self-seeded, stimulated Brillouin scattering (SBS) pulse compressor cell using SF6 at a density, ρ ca. 1 amagat can efficiently compress krypton fluoride (KrF) laser pulses at λ=248 nm. In order to avoid the generation of output pulses substantially shorter than τp, the optical power in the chirped input SBS ''seed'' beams was ramped. Compressed pulse conversion efficiencies of up to 68% were calculated for output pulse durations of τp ca. ns

  13. Surface analysis of the selective excimer laser patterning of a thin PEDOT:PSS film on flexible polymer films

    Science.gov (United States)

    Schaubroeck, David; De Smet, Jelle; Willems, Wouter; Cools, Pieter; De Geyter, Nathalie; Morent, Rino; De Smet, Herbert; Van Steenbeerge, Geert

    2016-07-01

    Fast patterning of highly conductive polymers like PEDOT:PSS (poly (3,4-ethylene dioxythiophene): polystyrene sulfonate) with lasers can contribute to the development of industrial production of liquid crystal displays on polymer foils. In this article, the selective UV laser patterning of a PEDOT:PSS film on flexible polymer films is investigated. Based on their optical properties, three polymer films are investigated: polyethylene terephthalate (PET), polymethyl methacrylate (PMMA) and cellulose triacetate (TAC). Ablation parameters for a 110 nm PEDOT:PSS film on these polymer films are optimized. A detailed study of the crater depth, topography and surface composition are provided using optical profilometry, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. The electrical insulation of the lines is measured and correlated to the crater analyses for different laser settings. Finally, potential ablation parameters for each of the polymer films are derived.

  14. Crystallization of amorphous Si films by excimer laser annealing%非晶硅薄膜的准分子激光晶化研究

    Institute of Scientific and Technical Information of China (English)

    秦娟娟; 邵景珍; 刘凤娟; 方晓东

    2015-01-01

    Amorphous silicon ( a:Si ) films were annealed by KrF excimer laser to realize the influence of different power density and different pulse counts. The analysis of a:Si thin film microstructure and surface morphology was conducted using X- ray diffractometer ( XRD ) and scanning electron microscope (SEM). In the range of 1 Hz, the results show that the polycrystalline silicon structure has been achieved from amorphous silicon by excimer laser annealing when the energy density reaches about 180 mJ/cm2. When the energy density is from the energy density threshold 180 mJ/cm2 to the energy density 230 mJ/cm2, the crystallization effect gets better with the increase of the energy density. The effect of crystallization is best and the gain size is the biggest while the energy density is 230 mJ/cm2. The maximum average size of the grain reaches 60 nm and the polycrystalline silicon film grows preferentially along the crystallographic(111) orientation. The influence of pulse counts are not remarkable if the pulse counts are over 50 times.%利用KrF准分子激光器晶化非晶硅薄膜,研究了不同的激光能量密度和脉冲次数对非晶硅薄膜晶化效果的影响。利用X射线衍射(XRD)和扫描电子显微镜(SEM)对晶化前后的样品的物相结构和表面形貌进行了表征和分析。实验结果表明,在激光频率为1 Hz的条件下,能量密度约为180 mJ/cm2时,准分子激光退火处理实现了薄膜由非晶结构向多晶结构的转变;当大于晶化阈值180 mJ/cm2小于能量密度230 mJ/cm2时,随着激光能量密度增大,薄膜晶化效果越来越好;激光能量密度为230 mJ/cm2时,晶化效果最好、晶粒尺寸最大,约60 nm,并且此时薄膜沿Si(111)面择优生长;脉冲次数50次以后对晶化的影响不大。

  15. FEM numerical analysis of excimer laser induced modification in alternating multi-layers of amorphous and nano-crystalline silicon films

    Energy Technology Data Exchange (ETDEWEB)

    Conde, J.C., E-mail: jconde@uvigo.es [Dpto. Fisica Aplicada, Universidade de Vigo, Rua Maxwell s/n, Campus Universitario Lagoas Marcosende, Vigo (Spain); Martin, E. [Dpto. Mecanica, Maquinas, Motores Termicos y Fluidos, Universidade de Vigo, Rua Maxwell s/n, Campus Universitario Lagoas Marcosende, Vigo (Spain); Stefanov, S. [Dpto. Fisica Aplicada, Universidade de Vigo, Rua Maxwell s/n, Campus Universitario Lagoas Marcosende, Vigo (Spain); Alpuim, P. [Departamento de Fisica, Universidade do Minho, 4800-058 Guimaraes (Portugal); Chiussi, S. [Dpto. Fisica Aplicada, Universidade de Vigo, Rua Maxwell s/n, Campus Universitario Lagoas Marcosende, Vigo (Spain)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer nc-Si:H is a material with growing importance for a large-area of nano-electronic, photovoltaic or biomedical devices. Black-Right-Pointing-Pointer UV-ELA technique causes a rapid heating that provokes the H{sub 2} desorption from the Si surface and bulk material. Black-Right-Pointing-Pointer Next, diffusion of P doped nc-Si films and eventually, for high energy densities would be possible to reach the melting point. Black-Right-Pointing-Pointer These multilayer structures consisting of thin alternating a-Si:H(10 nm) and n-doped nc-Si:H(60 nm) films deposited on SiO{sub 2}. Black-Right-Pointing-Pointer To optimize parameters involved in this processing, FEM numerical analysis of multilayer structures have been performed. Black-Right-Pointing-Pointer The numerical results are compared with exhaustive characterization of the experimental results. - Abstract: UV excimer laser annealing (UV-ELA) is an alternative annealing process that, during the last few years, has gained enormous importance for the CMOS nano-electronic technologies, with the ability to provide films and alloys with electrical and optical properties to fit the desired device performance. The UV-ELA of amorphous (a-) and/or doped nano-crystalline (nc-) silicon films is based on the rapid (nanoseconds) formation of temperature profiles caused by laser radiation that is absorbed in the material and lead to crystallisation, diffusion in solid or even in liquid phase. To achieve the desired temperature profiles and to optimize the parameters involved in the processing of hydrogenated nanocrystalline silicon (nc-Si:H) films with the UV-ELA, a numerical analysis by finite element method (FEM) of a multilayer structure has been performed. The multilayer structures, consisting of thin alternating a-Si:H(10 nm) and n-doped nc-Si:H(60 nm) layers, deposited on a glass substrate, has also been experimentally analyzed. Temperature profiles caused by 193 nm radiation with 25

  16. Whether does the granular corneal dystrophy indicate for the excimer laser ablation surgery or not%角膜颗粒状营养不良是否适合做准分子激光角膜切削术

    Institute of Scientific and Technical Information of China (English)

    张丰菊; 孙旭光

    2011-01-01

    随着准分子激光技术的飞速发展,角膜屈光手术方式的不断衍变,拓宽了手术的适应证.而对于伴有屈光不正的角膜营养不良者,临床上采用准分子激光角膜表面切削术(PRK)或采用乙醇法准分子激光上皮瓣下角膜磨镶术(LASEK)或激光治疗性角膜切削术(PTK)以及准分子激光角膜原位磨镶术(LASIK)进行治疗近期取得较好的效果,但术后的远期疾病复发和病情加重令人担忧,此类疾病是否适合行准分子激光角膜切削术?目前在临床治疗上尚需要明确.本文就该疾病的明确分型及确切诊断阐述了3种类型的角膜颗粒状营养不良的个体化治疗方案,旨在于指导临床合理地应用准分子激光角膜切削技术正确地治疗此类疾病,为患者提供安全、有效、持久满意的效果.%With the development of excimer laser technologies, the corneal refractive surgical procedures are improved constantly and the indication of excimer laser keratectomy is expanded. In clinic,PRK or LASEK or PTK or LASIK were performed on the eyes of granular corneal dystrophy with refractive error and the early results were satisfied, but the reoccurrence and server opacity of cornea are worried. Is this corneal disease the indication of excimer laser keratectomy? Nowadays, the exact indication for the disease should be declared in clinic. In this article, the customized treatment nomogram for three types of granular corneal dystrophy is explicated according to the clear classification and exact diagnosis on this disease, in order to apply the excimer laser keratectomy reasonably and correctly for the patient approaching the safe、 effective and long term satisfactory result.

  17. Clinical efficacy of 308 nm excimer laser in the treatment of 42 alopecia areata patients%308 nm准分子激光治疗斑秃42例疗效观察

    Institute of Scientific and Technical Information of China (English)

    梁俊琴; 彭艳玲; 普雄明

    2009-01-01

    目的 观察308 nm准分子激光治疗斑秃临床疗效及安全性.方法 :试验组用308 nm准分子激光对42例斑秃患者进行每周2~3次照射治疗并观察疗效.对照组:用浓度为5 mg/mL的曲安奈德液头部皮损内注射,沣射4~6周后观察疗效.结果 试验组与对照组差异具有统计学意义,试验组疗效好于对照组.试验组中有2例患者经过308 nm准分子激光5次后即有效,其余治疗有效患者中平均照射次数9.1次.结论 308 nm准分子激光治疗斑秃安全,有效,患者依从性较高.%Objective To observe the clinical efficacy and safety of 308 nm excimer laser treat alopecia areata patients.Methods 42 alopecia areata patients as test group are treated with 308 nm excimer laser 2-3 times a week and observe the effect of radiation treatment.30 alopecia aleata patients as Control group are treated by injectting the concentration of 5 mg/mL triamcinolone acetonideion fluid in the head lesions,4-6 weeks later observed effect.Results Test group and control group have statistically significant difference.Efficacy of the test group was better than the control group In test group two patients get Effective treatment after five times with 308 nm excimer laser treatment.The rest of the effective treatment of patients can get Effective treatment with an average of 9.1 times.Conclusion 308 nm excimer laser treat alopecia areata are more safe and effective,and patients have high compliance.

  18. Analysis of X-Ray Photoelectron Spectroscopy of Polymethyl Methacrylate Etched by a KrF Excimer Laser

    Institute of Scientific and Technical Information of China (English)

    ZHU Xiao-Li; LIU Shi-Bing; CHEN Tao; JIANG Yi-Jian; ZUO Tie-Chuan

    2005-01-01

    @@ The C1s and O 1s electrons in polymethyl methacrylate etched by different incident laser intensities are analysed by x-ray photoelectron spectroscopy. The results show that when the incident laser fluence increases gradually,the percentage of carbon atoms in C-C bonds decreases while the one in carbonyl group (C=O) and alkoxy group (C-O) increases, and the percentage of oxygen atoms in C=O bonds increases while the one in C-O bonds decreases. Based on the analysis of the chemical structure, the energy level transition, energy diversion, and dissociation of bonds are theoretically examined, which is consistent with the experimental results.

  19. A new and direct synthesis of lactic acid from acrylic acid using an excimer laser with high intensity

    International Nuclear Information System (INIS)

    A new and direct method of XeF (351 nm) laser irradiation of acrylic acid 1 solution containing H2O2 are described for the chemical synthesis of lactic acid 2. Increase in the yield strongly depended on the irradiation dose and H2O2 feeding rate, and the formation of 2 showed the quantum yield, 0.3, and the selectivity, 50%, at the maximum yield. Product analysis indicated that OH radicals formed with high density by the laser-photolysis of H2O2 are equally bonded to the carbons of α- and β-positions of 1 to produce 2 and 3-hydroxy propanoic acid with ratio of 1 to 1. (author)

  20. Photothermal Ablation of Polystyrene Film by 248 NM Excimer Laser Irradiation: a Mechanistic Study by Time-Resolved Measurements

    OpenAIRE

    Tsuboi, Yasuyuki; Sakashita, Shin-Ichi; Hatanaka, Koji; Fukumura, Hiroshi; Masuhara, Hiroshi

    1996-01-01

    Laser ablation mechanism at 248 nm irradiation of polystyrene film was investigated and discussed. An ablation threshold was determined by etch depth measurement and nanosecond photographic observation. Temperature at the threshold was evaluated to be 370℃ by using an effective absorption coefficient which was confirmed by transmission measurement of the excitation pulse. The temperature was in good agreement with that of thermal degradation of the polymer, showing that 248 nm ablation of pol...

  1. Four-year to seven-year outcomes of advanced surface ablation with excimer laser for high myopia

    DEFF Research Database (Denmark)

    Hansen, Rasmus Søgaard; Lyhne, Niels; Grauslund, Jakob; Grønbech, Keea Treu; Vestergaard, Anders Højslet

    2015-01-01

    Purpose: To evaluate and compare long-term outcomes ofafter photorefractive keratectomy with cooling (cPRK) and laser-assisted subepithelial keratectomy (LASEK) for high myopia. Methods: Retrospective single-masked follow-up study of patients treated for myopia between 2007 and 2009 with cPRK or...... ±1.0 D of intended refraction. Finally, 100% of cPRK patients and 92% of LASEK patients (P=0.87) were satisfied or very satisfied with the surgery at final follow-up. Conclusion: cPRK and LASEK seemed safe and with high patient satisfaction 4 to 7 years after surgery for high myopia. However, c...

  2. The interaction of 193-nm excimer laser irradiation with single-crystal zinc oxide: Positive ion emission

    International Nuclear Information System (INIS)

    We examine UV laser-induced ion emission from a wide bandgap semiconductor, single-crystal ZnO, at fluences well below both the damage threshold and plasma formation. At fluences below 200 mJ/cm2, we observe only Zn+, and the Zn+ intensity decreases monotonically during exposure. At higher fluences, after an initial decrease, the emission is sustained; in addition O+ and O2+ are observed. We explain: how Zn ions of several eV in energy can be produced on the surface of a semiconductor, how sustained emission can be maintained, and the origin of an anomalous emission of slow Zn+ ions -- the latter is shown to arise from photoionization of atomic Zn, also emitted by this radiation.

  3. Biological responses on NIH 3T3 to 193 NM excimer laser irradiation comparison with 254 irradiation

    International Nuclear Information System (INIS)

    During conventional UV radiations, activation of genes is tightly linked to the presence of DNA damages. At 254 nm, the major cellular chromophore is the nuclear DNA, with cyclobutane pyrimidine dimers being the major photoproduct. At 193 nm, DNA is more strongly absorbing than at 254 nm. However, the quantum yields of the photoproducts induced at these two wavelengths are different and damage to cellular DNA in the form of pyrimidine dimers or single-strand breaks was reported to be only marginal or undetected. Peptide bonds, many amino acid side chains, insaturated lipids, esters, and other cellular molecules absorb at 193 nm. Consequently, the most of the energy is thought to be absorbed by proteins, leaving the DNA shielded. About 60 % of the radiation can apparently be blocked by 1 μm of cytoplasm. However, exposures of cultured human fibroblasts to subablative doses of 193 nm laser radiation resulted in changes of genes expression such as collagenase, metallothionein and c-fos. The mechanisms by which the 193 nm radiation affects gene expression are not known. The site of primary interaction of the radiation could be different from the site of the genetic response. Thus, the signal transfer could pass through the cytoplasm via the nucleus. One hypothesis is that cytokines may regulate the transduction pathway event. By example, the TNF-alpha which is induced by UV-radiations. More, it can activate transcription factors such as AP-1 or c-fos and stimulate the growth of normal fibroblasts. Moreover, TNF-alpha plays a major role in the inflammatory processes by enhancing the remodeling of extracellular matrix in which mainly matrix metalloproteinases and collagenase participate. Besides, matrix metalloproteinases are responsive to cytokines and particularly the 92 kDa gelatinate (gelatinase B or metalloproteinase 9 or MMP 9) is induced and regulated by TNF-alpha. To understand the cellular response to high energy laser radiation, we investigated cell

  4. 本征非晶硅薄膜的准分子激光晶化%Crystallization of amorphous silicon based on excimer laser

    Institute of Scientific and Technical Information of China (English)

    段国平; 陈俊领; 周德让; 韩俊鹤; 黄明举

    2013-01-01

    In order to reduce the "S-W effect" of amorphous silicon thin film solar cells and increase its photoelectric conversion efficiency, intrinsic amorphous silicon thin films prepared by plasma enhanced chemical vapov deposition were crystallized with KrF excimer laser. The crystalline effect of the crystallized films under different laser energy density and repeated frequency was characterized with Raman spectroscopy, the morphologies of the samples before and after the crystallization was studied by means of scanning electron microscope. It is shown that the crystallization effect became better with the increase of laser energy density, maximum value of crystallization rate was 76. 34% when the energy density reached 268. 54mJ/cm2 and the optimum energy density range was from 204. 99mJ/cm2 to 268. 54mJ/cm2 in which the surface of film was crystallized well. In the range of lHz ~ lOHz, the crystallization effect got better with the increase of laser repeation frequency. Microcrystalline and polycrystal particles appeared obviously after the crystallization so that a good crystallization effect was achieved.%为了减低非晶硅薄膜太阳能电池的光致衰减效应和提高其光电转换效率,用等离子体化学气相沉积系统制备了本征非晶硅薄膜,用波长为248nm的KrF准分子激光器激光晶化了非晶硅表层,用共焦显微喇曼测试技术研究了非晶硅薄膜在不同的激光能量密度和不同的频率下的晶化状态,并用扫描电子显微镜测试晶化前后薄膜的形貌.结果表明,随着激光能量密度的增大,薄膜晶化效果越来越好,能量密度达到268.54mJ/cm2时晶化效果最好,此时结晶比约为76.34%;最佳的激光能量密度范围是204.99mJ/cm2~268.54mJ/cm2,这时薄膜表面晶化良好;在1Hz ~ 1OHz范围内,激光频率越大晶化效果越好;晶化后薄膜明显出现微晶和多晶颗粒,从而达到了良好的晶化效果.

  5. Pulsed laser deposition of rare earth compounds

    CERN Document Server

    Stone, L A

    2001-01-01

    Magnetostrictive thin films have been deposited using various techniques such as sputtering and evaporation but the use of laser deposition has been limited. This research presents the results from pulsed laser deposition (PLD) of TbFe sub 2 , DyFe sub 2 and Terfenol-D thin films using an infra red Transversely Excited Atmospheric (TEA) CO sub 2 laser at lambda approx 10.6 mu m and an ultra violet Argon-Fluoride (ArF) excimer laser at lambda approx 193 nm. Results have showed that the TEA CO sub 2 laser under the range of conditions studied is not suitable for the production of magnetostrictive films. The problems experienced are a mixture of mostly fracture debris at low fluences (F approx 20 Jcm sup - sup 2) and melt droplets at high fluences (F approx 60 Jcm sup - sup 2). In all cases the destruction of the target is a major problem, with the Terfenol-D targets being the worst affected. Thin films produced were all iron rich. The use of an excimer laser has proved more successful in providing stoichiometri...

  6. Pulsed laser deposition of rare earth compounds

    International Nuclear Information System (INIS)

    Magnetostrictive thin films have been deposited using various techniques such as sputtering and evaporation but the use of laser deposition has been limited. This research presents the results from pulsed laser deposition (PLD) of TbFe2, DyFe2 and Terfenol-D thin films using an infra red Transversely Excited Atmospheric (TEA) CO2 laser at λ ∼10.6 μm and an ultra violet Argon-Fluoride (ArF) excimer laser at λ ∼ 193 nm. Results have showed that the TEA CO2 laser under the range of conditions studied is not suitable for the production of magnetostrictive films. The problems experienced are a mixture of mostly fracture debris at low fluences (F ∼ 20 Jcm-2) and melt droplets at high fluences (F∼ 60 Jcm-2). In all cases the destruction of the target is a major problem, with the Terfenol-D targets being the worst affected. Thin films produced were all iron rich. The use of an excimer laser has proved more successful in providing stoichiometric transfer of the target material, although this is only true under certain conditions. When a rotating target was used the growth of stoichiometric films was difficult due to a process related to the high photon energy of the excimer laser. The use of single spot irradiation did provide films of near stoichiometric composition over a wide range of fluences. Magnetostrictions for both TbFe2 and DyFe2 were found to be quite similar λ// ∼ 280 ppm at an applied field of 980 kAm-1. The results for Terfenol-D films were quite low with λ// ∼ 190 ppm at 980 kAm-1 but these showed signs of being adversely affected by stresses created during deposition. (author)

  7. Keratin film ablation for the fabrication of brick and mortar skin structure using femtosecond laser pulses

    Science.gov (United States)

    Haq, Bibi Safia; Khan, Hidayat Ullah; Dou, Yuehua; Alam, Khan; Attaullah, Shehnaz; Zari, Islam

    2015-09-01

    The patterning of thin keratin films has been explored to manufacture model skin surfaces based on the "bricks and mortar" view of the relationship between keratin and lipids. It has been demonstrated that laser light is capable of preparing keratin-based "bricks and mortar" wall structure as in epidermis, the outermost layer of the human skin. "Bricks and mortar" pattern in keratin films has been fabricated using an ArF excimer laser (193 nm wavelength) and femtosecond laser (800 and 400 nm wavelength). Due to the very low ablation threshold of keratin, femtosecond laser systems are practical for laser processing of proteins. These model skin structures are fabricated for the first time that will help to produce potentially effective moisturizing products for the protection of skin from dryness, diseases and wrinkles.

  8. Combination Therapy of 308nm Excimer Laser and Topical Pimecrolimus in the Treatment of Vitiligo%308nm准分子激光联合吡美莫司软膏治疗白癜风临床观察

    Institute of Scientific and Technical Information of China (English)

    吴一菲; 曹萍; 薛琴; 王晓川; 王支琼; 杜鹏

    2011-01-01

    Objective To evaluate the efficacy and safety of combination therapy of pimecrolimus and 308nm excimer laser in the treatment of vitiligo. Methods One hundred and fifty patients of vitiligo were divided into three groups randomly. Fifty patients in treatment group were treated twice daily with pimecrolimus ointment combined with 308nm excimer laser twice weekly for 12 weeks. Similarly, 50 patients in control group 1 were only treated with 308nm excimer laser twice weekly for 12 weeks and 50 patients in control group 2 were only treated with pimecrolimus ointment twice daily for 12 weeks. Results The total effective rate was 88.00%, 70.00% and 42.00% in treatment groupm, control 1 and 2 respectively, which showed significant difference among three groups( P <0.05). The effect on face, neck, trunk and extremities was better in treatment group than in control group ( P < 0.05 ). However, there were no statistical significance among three groups in the effective rate of acral lesions( P > 0.05 ). No serious adverse events were recorded in three groups. Conclusion The combination of pimecrolimus ointment with 308nm excimer laser can represent an effective and well-tolerated therapy for vitiligo with face neck trunk and extremities involved.%目的 评价308nm准分子激光联合吡美莫司软膏治疗白癜风的疗效和安全性.方法 将150例白癜风患者随机分成3组.治疗组50例,308nm准分子激光(2坎/周)联合吡美莫司软膏(2次/d)治疗,疗程12周.对照1组50例,单纯予308nm准分子激光治疗,用法同上.对照2组50例,单纯予吡美莫司软膏治疗,用法同上.结果 治疗组有效率88.00%,对照1组为70.00%,对照2组为42.00%.治疗组和对照1组及对照2组比较,有效率差异有统计学意义(P0.05).患者均未出现严重不良反应.结论 308nm准分子激光联合吡美莫司软膏治疗位于面颈部、躯干和四肢的白癜风起效快,疗效好,不良反应少.

  9. Sequential amplitude divided angular multiplexing encoding optical system design for high power excimer laser system%连续分振幅式高功率准分子激光角多路编码光路设计

    Institute of Scientific and Technical Information of China (English)

    胡云; 王大辉; 赵学庆

    2016-01-01

    In high power excimer laser system, angular multiplexing technique is employed to achieve both high energy and narrow pulse output. In this article, angular multiplexing technique was introduced, and a multiplexing encoding method was presented. This method encoded seed beam in two steps by sequential amplitude splitting. The optical elements were arranged in rectangle arrays and piled by layers. A specific optical design was made for XeCl high power excimer laser system in this laboratory. This method of angular multiplexing encoding has advantages of compacted space, small encoding error, good compatibility with alignment and measurement, and is also easy to fabricate and assemble. This design is adopted in the system and performs well.%在高功率准分子激光系统中,一般采用光学角多路技术来获得高能量窄脉冲输出。文中介绍了角多路技术原理,提出了一种采用矩形阵列和空间层叠光路结构的连续分振幅两次编码方式,并针对该实验室的XeCl高功率准分子激光系统进行了具体的编码光路设计,给出了设计实例。该方法具有编码结构紧凑,编码精度高,与光路准直、激光参数测量系统等兼容性好,便于加工制作和安装调节等优点,目前已在系统中应用,效果良好。

  10. Seven year follow-up after advanced surface ablation with excimer laser for treatment of myopia: Long-term outcomes of cooling PRK and LASEK

    DEFF Research Database (Denmark)

    Hansen, Rasmus Søgaard; Lyhne, Niels; Grauslund, Jakob;

    , Odense University Hospital. Inclusion criteria: Age 20-50 years at time of surgery, pre-operative CDVA ≤ 0.10 (logMAR) and no other ocular conditions than myopia with or without astigmatism of maximum 3 D. Exclusion criteria: Pregnancy and eyes having undergone re-treatment. A MEL80 flying-spot excimer...... were satisfied or very satisfied with the surgery 5 to 7 years after surgery. Conclusions: Both cPRK and LASEK seemed safe up to 7 years after surgery for treatment of myopia and low degrees of astigmatism. Results were comparable concerning refractive predictability, visual acuity, corneal haze...

  11. Laser shaping of corneal transplants in vitro: area ablation with small overlapping laser spots produced by a pulsed scanning laser beam using an optimizing ablation algorithm

    International Nuclear Information System (INIS)

    Area laser lathing and trephination of donor corneas is used to produce different types of grafts for human transplantation. 193 nm (ArF excimer) laser radiation is used, since this is known to give a non-thermal laser-tissue interaction with a minimal zone of tissue damage. To guarantee the highest degree of flexibility concerning the overall shape of the grafts as well as their thickness profiles, we use a small (compared with the area to be ablated) scanning laser spot. For area lathing of the tissue we have developed a new ablation algorithm (optimized scanning laser ablation, OSLA) that can be applied to lathe and perforate any tissue - with concave (as in this application), convex or plane surface geometry - where surface precision and smoothness are key issues. Using OSLA with the Excimer Laser Corneal Shaping System (a tool for in vitro fabrication of all kinds of corneal transplants like donor buttons for keratoplasty, lamellar grafts for epikeratoplasty and refractive lenticules) enabled us to produce all types of corneal grafts with very high precision. This is considered to be a major improvement towards the production of refractive lenticules. (author)

  12. Preliminary results of tracked laser-assisted in-situ keratomileusis (T-LASIK) for myopia and hyperopia using the autonomous technologies excimer laser system

    Science.gov (United States)

    Maguen, Ezra I.; Nesburn, Anthony B.; Salz, James J.

    2000-06-01

    A study was undertaken to assess the safety and efficacy of LASIK with the LADARVision laser by Autonomous Technologies, (Orlando, FL). The study included four subsets: Spherical myopia -- up to -11.00D, spherical hyperopia -- up to +6.00D. Both myopic and hyperopic astigmatism could be corrected, up to 6.00D of astigmatism. A total of 105 patients participated. Sixty-six patients were myopic and 39 were hyperopic. The mean (+/- SD) age was 42.8 +/- 9.3 years for myopia and 53.2 +/- 9.9 years for hyperopia. At 3 months postop. Sixty-one myopic eyes were available for evaluation. Uncorrected visual acuity was 20/20 in 70% of eyes and 20/40 in 92.9% of all eyes. The refractive outcome was within +/- 0.50D in 73.8% of eyes and within +/- 1.00D in 96.7 of eyes. Thirty-eight hyperopic eyes were available. Uncorrected visual acuity was 20/20 in 42.1% of eyes and 20/40 in 88% of all eyes. The refractive outcome was within +/- 0.50D in 57.9% of eyes and within +/- 1.00D in 86.8% of eyes. Complications were not sight threatening and were discussed in detail. Lasik with the LADARVision laser appears to be safe and effective.

  13. Optical Emission Spectroscopy of the Laser Ablation Plume Controled by RF Plasma

    Science.gov (United States)

    Suda, Yoshiyuki; Nishimura, Takuma; Mizuno, Manabu; Bratescu, Maria Antoaneta; Sakai, Yosuke

    1999-10-01

    Recently, film deposition has been investigated using laser ablation methods which have a lot of advantages. For the purpose of control of the laser ablation plume, we introduced a radio frequency (RF) plasma. In this report we present position resolved optical emission spectra of the plume observed by an OMA (optical multichannel analyzer). The plume current is also measured. The RF plasma is generated in a helical coil installed between the substrate and the target. An ArF excimer laser (wavelength 193 nm, pulse duration time 20 ns) is used as a light source, and the target material is sintered carbon graphite. The laser fluence on the target surface is changed in a range from 1.2 to 6.4 J/cm^2. Ar gas is introduced to sustain the RF plasma. When the plume goes through the RF plasma, interaction of the plume with the plasma is expected. The possibility of control of the plume behavior is discussed.

  14. Excimer UV curing in printing

    International Nuclear Information System (INIS)

    It is the aim of this study to investigate the potential of 308 run excimer UV curing in web and sheet fed offset printing and to discuss its present status. Using real-time FTIR-ATR and stationary or pulsed monochromatic (313 nm) irradiation chemical and physical factors affecting the curing speed of printing inks such as nature and concentration of photo-initiators, reactivity of the ink binding system, ink thickness and pigmentation, irradiance in the curing plane, oxygen concentration and nitrogen inerting, multiple pulse exposure, the photochemical dark reaction and temperature dependence were studied. The results were used to select optimum conditions for excimer UV curing in respect to ink reactivity, nitrogen inerting and UV exposure and to build an excimer UV curing unit consisting of two 50 W/cm 308 run excimer lamps, power supply, cooling and inerting unit. The excimer UV curing devices were tested under realistic conditions on a web offset press zirkon supra forte and a sheet fed press Heidelberg GTO 52. Maximum curing speeds of 300 m/min in web offset and 8000 sheets per hour in sheet fed offset were obtained

  15. 3D plasmonic transducer based on gold nanoparticles produced by laser ablation on silica nanowires

    Science.gov (United States)

    Gontad, F.; Caricato, A. P.; Manera, M. G.; Colombelli, A.; Resta, V.; Taurino, A.; Cesaria, M.; Leo, C.; Convertino, A.; Klini, A.; Perrone, A.; Rella, R.; Martino, M.

    2016-05-01

    Silica two-dimensional substrates and nanowires (NWs) forests have been successfully decorated with Au nanoparticles (NPs) through laser ablation by using a pulsed ArF excimer laser, for sensor applications. A uniform coverage of both substrate surfaces with NPs has been achieved controlling the number of laser pulses. The annealing of the as-deposited particles resulted in a uniform well-defined distribution of spherical NPs with an increased average diameter up to 25 nm. The deposited samples on silica NWs forest present a very good plasmonic resonance which resulted to be very sensitive to the changes of the environment (ethanol/water solutions with increasing concentration of ethanol) allowing the detection of changes on the second decimal digit of the refractive index, demonstrating its potentiality for further biosensing functionalities.

  16. Photoassociative Excitation Spectroscopy of Excimer Molecules

    Science.gov (United States)

    Jones, Ronald Blake

    Laser excitation spectroscopy of transitions having dissociative ground states was explored as a tool for the study of excimer molecules. Since the repulsive nature of the ground state constrains collision pairs to large internuclear transitions, bound >=ts free excitation spectra contain more structure than the bound to free fluorescence spectra for the same molecules, therefore containing more information about the potential surfaces. Unique properties of the photoassociative excitation spectroscopy technique are described which allow the dependence of the dipole transition moment on the internuclear separation (mu (R)) to be extracted in a very direct manner. Excitation spectra are presented for the B >=ts X transitions of KrF and XeI for the wavelength (lambda) interval 206 nm KrI are given. This work required the development of a tunable VUV source, which is described.

  17. Yb:Lasers for high repetition rate VUV ultrafast chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Backus, Sterling [KMLabs Inc.. Boulder, CO (United States)

    2016-07-18

    Currently the shortest-wavelength commercially available laser is the ArF excimer laser. Remarkably, the ArF wavelength is less then a factor of 4 shorter than the wavelength of the first laser demonstrated—the Ruby laser at 694 nm, demonstrated in 1960. This relatively modest progress in generating shorter-wavelength light reflects the physics of the stimulated emission process— which teaches that the base power requirement for implementing a laser scales as λ-5— and not a lack of compelling need for shorter-wavelength sources. In-fact, the need for laser sources at wavelengths extending from the deep-UV into the vacuum-UV (VUV) region of the spectrum (i.e. 100-250 nm) has become acute. For example, Figure 1 diagrams the basic principle behind the laser-based dark-field wafer inspection technology widely used in the semiconductor industry to map the location of every defect >~40 nm in size over the surface of a wafer: the equivalent of mapping the location of any defect larger than an ant in an area the size of Manhattan. This technique relies on light scattering, whose intensity scales as ~(d/λ)4, where d is the defect dimension. Current wafer defect inspection systems are reaching their limits as microelectronics critical dimensions shrink from the current 14 nm state-of-the-art to 10, 7 and then 5 nm in the next decade. Current generation systems use light at 266 nm from a frequency-quadrupled Nd laser system. But attempts to use, for example, 213 nm have not been successful in high-volume manufacturing because of the limited power and lifetime of the lasers. This inspection is typically done in vacuum, and thus moving to wavelength as short as 100 nm could dramatically improve sensitivity.

  18. 308nm激光联合胡椒碱对表皮黑素细胞中黑素合成及酪氨酸相关蛋白水平的影响%Effects of Combination of 308 nm Excimer Laser with Piperine on the Melanin Synthesis of Epidermal Melanophore and Expression of Tyrosine Related Proteases

    Institute of Scientific and Technical Information of China (English)

    吴一菲; 曹萍; 王晓川; 关真; 陈伟; 刘畅

    2016-01-01

    Objective To study the response of the melanin synthesis and the expression of tyrosine related proteases of epidermal melanophore to the combination of 308nm excimer laser with piperine and discuss the mechanism of melanogenesis in response to different treatment.Methods Epidermal melanophore from the combination intervene group, the 308nm excimer laser group, the piperine group, the positive control group and the control group were incubated for 24h,72h and 120h.Then the melanin content and the expression of TRP-1 and TRP-2 were measured (Quantitative analysis of laser confocal fluorescence).Results The combination intervene group, the 308nm excimer laser group, the piperine group and the positive control group could promote the cellular melanin content and the activity of TRP-1 and TRP-2 at different degrees.The combination intervene group played the strongest role though.Conclusion 308nm excimer laser combination with piperine can apparently increase the pigmentation of epidermal melanophore.%目的 研究308nm激光联合胡椒碱对表皮黑素细胞中黑素合成及酪氨酸相关蛋白水平的影响,初步探讨不同分组对黑素合成的作用机制.方法 培养的表皮黑素细胞分别以308nm激光联合胡椒碱(联合干预组)、308nm激光组、胡椒碱组、阳性对照组及空白对照组作用24h,72h及120h后,测定细胞黑素含量及酪氨酸相关蛋白(TRP-1,TRP-2)活性(激光共聚焦荧光定量分析法).结果 联合干预组、308nm激光组、胡椒碱组、阳性对照组均不同程度促进黑素含量及TRP-1,TRP-2活性的增高.其中以联合干预组促进作用最强.结论 308nm激光联合胡椒碱有明显促进表皮黑素细胞黑素合成作用.

  19. Cross-shaped photoluminescence of excimers in perylene crystals

    Science.gov (United States)

    Tanaka, Daichi; Numata, Yudai; Nakagawa, Kazuya; Kobayashi, Takayoshi; Tokunaga, Eiji

    2016-06-01

    Cross-shaped excimer (self-trapped exciton) luminescence from α- and β-perylene single crystals of 50-100 μm was found when they were excited at the center of the crystals with a continuous-wave (cw) laser resonant with the exciton absorption. The cross shape is formed by the two lines which intersect at the excited position and are perpendicular to the sides of the crystals of parallelogram shape. Luminescence is emitted from the excited spot and 4 side edges in the cross shape. The most striking feature is that the luminescence intensity at the edges was as high as or higher than at the excited spot. The possibility of the exciton propagation or the waveguide effect is rejected both experimentally and theoretically. This phenomenon can be reasonably explained only when the radiative transition probability of excimers is significantly enhanced at the crystals side edges than at the center due to the lower symmetry.

  20. Cross-shaped photoluminescence of excimers in perylene crystals

    Science.gov (United States)

    Tanaka, Daichi; Numata, Yudai; Nakagawa, Kazuya; Kobayashi, Takayoshi; Tokunaga, Eiji

    2016-04-01

    Cross-shaped excimer (self-trapped exciton) luminescence from α- and β-perylene single crystals of 50-100 μm was found when they were excited at the center of the crystals with a continuous-wave (cw) laser resonant with the exciton absorption. The cross shape is formed by the two lines which intersect at the excited position and are perpendicular to the sides of the crystals of parallelogram shape. Luminescence is emitted from the excited spot and 4 side edges in the cross shape. The most striking feature is that the luminescence intensity at the edges was as high as or higher than at the excited spot. The possibility of the exciton propagation or the waveguide effect is rejected both experimentally and theoretically. This phenomenon can be reasonably explained only when the radiative transition probability of excimers is significantly enhanced at the crystals side edges than at the center due to the lower symmetry.

  1. Amplification of high power short pulse excimer laser with beam smoothing%平滑化窄脉冲高功率准分子激光放大技术

    Institute of Scientific and Technical Information of China (English)

    赵学庆; 黄坷; 黄超; 于力; 刘晶儒; 易爱平; 薛全喜; 华恒祺; 钱航; 郑国鑫; 胡云; 张永生

    2011-01-01

    The combination of optical angular mutiplexing and Echelon Free Induced Spatial Incoherence (EFISI) is a best choice for the pulse compression and beam smoothing in a high power excimer laser system, which relates to the transportation and amplification of smoothed narrow laser pulse mainly. In this paper, the construction of a partial coherence oscillator by scattering method was described and primary results for pulse shaping were provided. Then, the gain characteristics for five laser amplifiers by single-pass amplifications and simulations of different output couplings were discussed, and measures to control over Amplification Spontaneous Emission (ASE) in the short laser pulse amplification was described. Finally, the Main Oscilation Power Amplifer (MOPA) chain of a single-beam XeCl laser and primary results were introduced. Obtained results show that the final output energy is 5-6 J with a pulsewidth around 10 ns and the focal spot is around 300 μm in the diameter. These results indicate that the laser chain and optical design are reasonable, which can be used as a good guide for the specific design of full scale angular multiplexed laser MOPA system.%对于高功率准分子激光,光学角多路和诱导空间非相干(EFISI)光束平滑是高功率准分子激光压缩脉宽、提高功率密度和实现靶面均匀辐照的有效途径,其应用涉及前端至靶前的各个环节,主要体现为平滑化窄脉冲激光的传输放大问题.首先介绍了基于散射法开展的部分相千源前端技术及脉冲整形的初步研究结果,利用直接法和反射率耦合方法,研究了5台激光放大器增益特性.然后,讨论了窄脉宽激光放大时的自发辐射放大(ASE)控制技术,最后,介绍了窄脉冲激光放大实验系统.实验获得了预期的实验结果,输出能量为5~6 J,激光脉宽约10 ns,聚焦光斑约Φ300 μm.单路系统实验结果表明,系统放大链和光学设计合理,基本满足角多路MOPA系统的

  2. Numerical studies of temperature profile and hydrodynamic phenomena during excimer laser assisted heteroepitaxial growth of patterned silicon and germanium bi-layers

    Energy Technology Data Exchange (ETDEWEB)

    Conde, J.C., E-mail: jconde@uvigo.e [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain); Chiussi, S. [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain); Martin, E. [Dpto. de Mecanica, Maquinas Motores Termicos y Fluidos, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain); Gontad, F. [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain); Fornarini, L. [Enea-Frascati, Via Enrico Fermi 45, I-00044 Frascati Roma (Italy); Leon, B. [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain)

    2010-01-01

    In this manuscript, a 3-D axisymmetric model for the heteroepitaxial growth induced by irradiating thin patterned amorphous hydrogenated silicon (a-Si:H) and germanium (a-Ge:H) bi-layers on Si (100) with pulsed UV-laser radiation, is presented. For reducing optimization steps, an efficient simulation of the laser induced processes that include rapid heating and solidification phenomena in the range of several tenth of nanoseconds, must be performed, if alloy composition and quality has to be adjusted. In this study, the effects of various laser energy densities on different amorphous Si/Ge bi-layer structures has been predicted and adjusted to obtain the desired Ge concentration profiles for applications as sacrificial layers, i.e. a Ge containing film buried under a Si rich surface layer. The numerical model includes the temperature dependent variations of the thermophysical properties and takes the coupled effects of temperature and hydrodynamic phenomena for a Boussinesq fluid, to estimate the element interdiffusion during the process and predicting the concentration profiles.

  3. Effect of the Sn dopant on the crystallization of amorphous Ge2Sb2Te5 films induced by an excimer laser

    Science.gov (United States)

    Bai, N.; Liu, F. R.; Han, X. X.; Zhu, Z.; Liu, F.; Lin, X.; Sun, N. X.

    2015-11-01

    In this paper, the influence of Sn doping (0%, 8%, and 14%) on the crystallization of Ge2Sb2Te5 (GST) was studied with the aid of an ultraviolet laser. It was found that the addition of Sn element not only expanded the lattice parameter but also decreased the crystallization temperature and activation energy as compared to the GST. As compared to the Ge2Sb2Te5, a more complete crystallization of the Sn doping Ge2Sb2Te5 is mainly due to the lower binding energy of Sn-Te (359.8 kJ/mol), which could be more easily taken part in the bond breakage and formation than Ge-Te (456 kJ/mol) in such a short time as 30 ns. The equiaxial grains were obtained for the Sn8Ge15Sb23Te54 films when crystallization was induced by the laser fluence of 20 mJ/cm2 but the grains elongated when the laser fluence was increased to 60 mJ/cm2. The reason may be the incorporation of Sn elements changed the crystal nucleation mode.

  4. Auxin-dependent compositional change in Mediator in ARF7- and ARF19-mediated transcription.

    Science.gov (United States)

    Ito, Jun; Fukaki, Hidehiro; Onoda, Makoto; Li, Lin; Li, Chuanyou; Tasaka, Masao; Furutani, Masahiko

    2016-06-01

    Mediator is a multiprotein complex that integrates the signals from transcription factors binding to the promoter and transmits them to achieve gene transcription. The subunits of Mediator complex reside in four modules: the head, middle, tail, and dissociable CDK8 kinase module (CKM). The head, middle, and tail modules form the core Mediator complex, and the association of CKM can modify the function of Mediator in transcription. Here, we show genetic and biochemical evidence that CKM-associated Mediator transmits auxin-dependent transcriptional repression in lateral root (LR) formation. The AUXIN/INDOLE 3-ACETIC ACID 14 (Aux/IAA14) transcriptional repressor inhibits the transcriptional activity of its binding partners AUXIN RESPONSE FACTOR 7 (ARF7) and ARF19 by making a complex with the CKM-associated Mediator. In addition, TOPLESS (TPL), a transcriptional corepressor, forms a bridge between IAA14 and the CKM component MED13 through the physical interaction. ChIP assays show that auxin induces the dissociation of MED13 but not the tail module component MED25 from the ARF7 binding region upstream of its target gene. These findings indicate that auxin-induced degradation of IAA14 changes the module composition of Mediator interacting with ARF7 and ARF19 in the upstream region of their target genes involved in LR formation. We suggest that this regulation leads to a quick switch of signal transmission from ARFs to target gene expression in response to auxin. PMID:27217573

  5. The Correction of Moderate and Severe Myopia with the Excimer Laser%准分子激光治疗高度和超高度近视

    Institute of Scientific and Technical Information of China (English)

    高殿文; 冯雪梅; 陈立忠; 裴莹; 盖春柳

    2001-01-01

    目的评价准分子激光原位角膜磨镶术(laser in-situ keratomileusis, LASIK)和准分子激光角膜切削术(photorefractive keratectomy, PRK)治疗高度、超高度近视的临床效果.方法对于术前近视-6.00~-14.75D的患者102只眼施行PRK手术,近视-6.00~-22.00D的患者118只眼施行LASIK手术.按术前屈光度分组,Ⅰ组:-6.00~-9.75D;Ⅱ组:-10.00~-14.75D;Ⅲ组:-15.00~-22.00D.术后随访半年以上,并将结果比较分析.结果术后裸眼视力≥0.5者,Ⅰ组中PRK为93.9%;LASIK为98.4%.Ⅱ组中PRK为75.0%;LASIK为93.8%.Ⅲ组中PRK为0.0%;LASIK为65.2%.术后裸眼视力≥1.0者,,Ⅰ组中PRK为79.2%;LASIK为82.5%.Ⅱ组中PRK为35.0%;LASIK为46.9%.Ⅲ组中PRK为0.0%;LASIK为8.7%.术后屈光度在±1.0D以内者:Ⅰ组中PRK为63.4%;LASIK为66.7%.Ⅱ组中PRK为15.0%;LASIK为46.9%.Ⅲ组中PRK为0.0%;LASIK为8.7%.角膜上皮下混浊:PRK治疗组中占59.8%;而LASIK则占4.2%.术后散光增加:PRK治疗组为17.6%;LASIK治疗组占21.2%,尚未发现严重并发症.结论对高度和超高度近视患者,LASIK临床治疗效果优于PRK手术.

  6. Fabrication of 250-nm-hole arrays in glass and fused silica by UV laser ablation

    Science.gov (United States)

    Karstens, R.; Gödecke, A.; Prießner, A.; Ihlemann, J.

    2016-09-01

    Parallel nanohole drilling in glass using an ArF excimer laser (193 nm) is demonstrated. For the first time, hole arrays with 500 nm pitch and individual holes with 250 nm diameter and more than 100 nm depth are fabricated by phase mask imaging using a Schwarzschild objective. Holes in soda lime glass are drilled by direct ablation; fused silica is processed by depositing a SiOx-film on SiO2, patterning the SiOx by ablation, and finally oxidizing the remaining SiOx to SiO2. Thermally induced ordered dewetting of noble metal films deposited on such templates may be used for the fabrication of plasmonic devices.

  7. A method of atmospheric density measurements during space shuttle entry using ultraviolet-laser Rayleigh scattering

    Science.gov (United States)

    Mckenzie, Robert L.

    1988-01-01

    An analytical study and its experimental verification are described which show the performance capabilities and the hardware requirements of a method for measuring atmospheric density along the Space Shuttle flightpath during entry. Using onboard instrumentation, the technique relies on Rayleigh scattering of light from a pulsed ArF excimer laser operating at a wavelength of 193 nm. The method is shown to be capable of providing density measurements with an uncertainty of less than 1 percent and with a spatial resolution along the flightpath of 1 km, over an altitude range from 50 to 90 km. Experimental verification of the signal linearity and the expected signal-to-noise ratios is demonstrated in a simulation facility at conditions that duplicate the signal levels of the flight environment.

  8. Laser ablation synthesis of zinc oxide clusters: a new family of fullerenes?

    CERN Document Server

    Bulgakov, A V; Bulgakov, Alexander V.; Ozerov, Igor; Proxy, Wladimir Marine; ccsd-00000864, ccsd

    2003-01-01

    Positively charged zinc oxide clusters ZnnOm (up to n = 16, m <= n) of various stoichiometry were synthesized in the gas phase by excimer ArF laser ablation of a ZnO target and investigated using time-of-flight mass spectrometry. Depending on ablation conditions, either metal rich or stoichiometric clusters dominate in the mass spectrum. When the irradiated target surface is fairly fresh, the most abundant clusters are metal rich with Zn(n+1)On and Zn(n+3)On being the major series. The stoichiometric clusters are observed with an etched ablated surface. The magic numbers at n = 9, 11 and 15 in mass spectra of (ZnO)n clusters indicate that the clusters have hollow spheroid structures related to fullerenes. A local abundance minimum at n = 13 provides an additional evidence for the presence in the ablation plume of fullerene-like (ZnO)n clusters.

  9. An excimer-based FAIMS detector for detection of ultra-low concentration of explosives

    Science.gov (United States)

    Chistyakov, Alexander A.; Kotkovskii, Gennadii E.; Sychev, Alexey V.; Perederiy, Anatoly N.; Budovich, V. L.; Budovich, D. V.

    2014-05-01

    A new method of explosives detection based on the field asymmetric ion mobility spectrometry (FAIMS) and ionization by an excimer emitter has been developed jointly with a portable detector. The excimer emitter differs from usual UVionizing lamps by mechanism of emitting, energy and spectral characteristics. The developed and applied Ar2-excimer emitter has the working volume of 1 cm3, consuming power 0.6 W, the energy of photons of about 10 eV (λ=126 nm), the FWHM radiation spectrum of 10 nm and emits more than 1016 photon per second that is two orders of magnitude higher than UV-lamp of the same working volume emits. This also exceeds by an order of magnitude the quantity of photons per second for 10-Hz solid state YAG:Nd3+ - laser of 1mJ pulse energy at λ=266 nm that is also used to ionize the analyte. The Ar2-excimer ionizes explosives by direct ionization mechanism and through ionization of organic impurities. The developed Ar2-excimer-based ion source does not require cooling due to low level discharge current of emitter and is able to work with no repair more than 10000 hrs. The developed excimer-based explosives detector can analyze both vapors and traces of explosives. The FAIMS spectra of the basic types of explosives like trinitrotoluene (TNT), cyclotrimethylenetrinitramine (RDX), dinitrotoluene (DNT), cyclotetramethylenetetranitramine (HMX), nitroglycerine (NG), pentaerythritol tetranitrate (PETN) under Ar2-excimer ionization are presented. The detection limit determined for TNT vapors equals 1x10-14 g/cm3, for TNT traces- 100 pg.

  10. Discharge-current characteristics in UV-preionized Kr/He, F2/He gas-mixtures and KrF excimer laser gas. Shigaisen yobi denri Kr/He, F2/He kongo kitai hoden oyobi KrF laser reiki hoden no denryu tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Nakagawa, N.; Kawakami, H.; Yukimura, K. (Doshisha University, Kyoto (Japan))

    1992-08-15

    In order to study effects of Kr and F2 on discharge characteristics of KrF excimer laser gas, gap phenomena in Kr/He and F2/He gas-mixtures were observed and discharge current (I[sub d]) was measured. In the range where Kr concentration was over 10% in Kr/He gas, in which production of filamentation as well as glow discharge started, discontinuous change in I[sub d] in the second or third half cycle was observed. According to the results of experiments and model analyses, it was considered that the discontinuity of the current showed the transition point to filamentation. When F2 concentration was in the range between 0.1 and 0.3% in F2/He mixture gas, filamentation and arc with glow were observed. Sine-waveform I[sub d] ended in the first half cycle, and began to flow again after cessation or had almost constant current due to arc and others. When F2 was over 0.4%, only are discharge was observed. It was thus found that F2 has a large effect on discharge characteristics of KrF laser gas. 18 refs., 9 figs.

  11. Bayesian classification of residues associated with protein functional divergence: Arf and Arf-like GTPases

    Directory of Open Access Journals (Sweden)

    Neuwald Andrew F

    2010-12-01

    Full Text Available Abstract Background Certain residues within proteins are highly conserved across very distantly related organisms, yet their (presumably critical structural or mechanistic roles are completely unknown. To obtain clues regarding such residues within Arf and Arf-like (Arf/Arl GTPases--which function as on/off switches regulating vesicle trafficking, phospholipid metabolism and cytoskeletal remodeling--I apply a new sampling procedure for comparative sequence analysis, termed multiple category Bayesian Partitioning with Pattern Selection (mcBPPS. Results The mcBPPS sampler classified sequences within the entire P-loop GTPase class into multiple categories by identifying those evolutionarily-divergent residues most likely to be responsible for functional specialization. Here I focus on categories of residues that most distinguish various Arf/Arl GTPases from other GTPases. This identified residues whose specific roles have been previously proposed (and in some cases corroborated experimentally and that thus serve as positive controls, as well as several categories of co-conserved residues whose possible roles are first hinted at here. For example, Arf/Arl/Sar GTPases are most distinguished from other GTPases by a conserved aspartate residue within the phosphate binding loop (P-loop and by co-conserved residues nearby that, together, can form a network of salt-bridge and hydrogen bond interactions centered on the GTPase active site. Residues corresponding to an N-[VI] motif that is conserved within Arf/Arl GTPases may play a role in the interswitch toggle characteristic of the Arf family, whereas other, co-conserved residues may modulate the flexibility of the guanine binding loop. Arl8 GTPases conserve residues that strikingly diverge from those typically found in other Arf/Arl GTPases and that form structural interactions suggestive of a novel interswitch toggle mechanism. Conclusions This analysis suggests specific mutagenesis experiments to

  12. 近视患者飞秒制瓣准分子激光术后视力改善情况及相关影响因素分析%Analysis of visual acuity improvement and related factors for myopia patients after Femtosecond flap excimer laser surgery

    Institute of Scientific and Technical Information of China (English)

    唐平; 王康宏; 陈梨萍

    2014-01-01

    目的:探讨近视患者飞秒制瓣准分子激光术后视力改善情况及其影响因素。方法:收集2010年1月至2013年12月期间,我院收治的近视患者72例(129眼),采用飞秒制瓣准分子激光术治疗,观察术后视力改善情况,并分析其影响因素。结果:患者的术后远视力(VA)、近视力(NVA)及最佳矫正视力(BCVA)均较术前显著提高(P<0.05);Logistic回归分析显示,术前BCVA、NVA、眼轴长度、切削比、眼轴长度以及术后视近时间均是术后视力的影响因素(P<0.05)。结论:飞秒制瓣准分子激光术治疗近视具有显著疗效,术后视力受术前BCVA、NVA、切削比、眼轴长度以及术后视近时间等的影响。%Objective To investigate the visual acuity improvement and related factors for myopia after femtosecond flap excimer laser surgery. Methods 72 myopic patients (129 eyes) in our hospital between January 2010 and December 2013 were chosen. The patients all received femtosecond flap excimer laser surgery. The visual acuity improvement after surgery was observed, and the influencing factors were analyzed. Results The distance vision (VA), near vision (NVA) and best corrected visual acuity (BCVA) significantly increased before surgery (P<0.05). Logistic regression analysis showed that preoperative BCVA, NVA, axial length, cutting ratio, axial length and time of near vision were the affecting factors of visual acuity (P<0.05). Conclusion Femtosecond flap excimer laser surgery for myopia has significant effect , but the preoperative visual acuity was affected by BCVA , NVA, cutting ratio, axial length and time of near vision.

  13. 中药五白散对308nm准分子激光诱导色素沉着动物模型的影响%Influence of Wubai Powder on Pigmentation Animal Model induced by 308nm Excimer Laser

    Institute of Scientific and Technical Information of China (English)

    查伟锋; 宋为民; 艾俊俊; 郑俊惠; 胡玲玲

    2012-01-01

    Objective:To observe the influence of Wubai Powder on pigmentation animal model induced by 308nrn ex-cimer laser. Methods:308nm excimer laser induced pigmentation animal model. After establishing the model,the areas of pigmentation were divided into 3 group:single matrix cream group,2% hydroquinone group and Wubai Powder group,and daubed them on corresponding lesions. After treamting for 30 days,the efficacy of the tested drug was evaluated comprehensively by measurements of melanin index, melanocyte, melanin as well as the histopathology of skin. Result: It was shown that the tested drug can decrease the level of melanin index,restrain the activity of melanocyte,reduce the generation of melanin and relieve pigmentation caused by UVB. Conclusion: Wubai Powder had obvious treatment function on 308nm excimer laser - induced pigmentation, its mechanism was to inhibit the activity of tyrosinase,which decreased melanin generation.%目的:探讨中药五白散对308nm准分子激光诱导的色素沉着豚鼠模型的影响.方法:308nm准分子激光诱导色素沉着豚鼠模型.造模成功后,色素沉着区分为单纯基质乳膏组、2%氢醌组和中药五白散组,分别对应外涂于皮损区.外用治疗30无后,对各组的黑色素指数、黑素细胞、黑素颗粒及皮肤组织病理学检查观察药物的疗效和安全性.结果:五白散可降低黑色素指数水平,抑制黑素细胞活性,减少黑素生成,减轻UVB所致皮肤色素沉着的程度.结论:中药五白散对308nm准分子激光诱导豚鼠色素沉着有明显的改善作用,其机制可能是一定程度上抑制酪氨酸酶活性,减少黑素生成.

  14. 308 nm excimer laser combined with piperine activated the production of melanin in amelanotic melanocytes in outer root sheath of hair%308 nm激光联合胡椒碱促进毛囊外根鞘无色素黑色素细胞黑色素合成

    Institute of Scientific and Technical Information of China (English)

    吴栋杰

    2015-01-01

    Objective To study the mechanism of 308 nm excimer laser combined with piperine activated the production of melanin in amelanotic melanocytes in outer root sheath of hair(AMMC) ,and promote the expression of TRP‐1、TRP‐2 protein . Methods AMMC were in incubated for 24、72、120 h in different groups(combination therapy group ,the 308 nm excimer laser group ,the piperine group ,the positive control group and the control group) .Then the melanin content was measured .The expres‐sion change of TRP‐1 and TRP‐2 in cells were observed by laser scanning confocal microscopy .Results Four groups increased the AMMC cellular melanin content .Four different groups could promote melanin content at different degrees .The combination therapy group played the strongest role in promoting function .And the function was the most obviously in 24 h ,it also was concentration dependent .0 .5 mmol/L piperine in combination group and piperine group could produce promoting effect of within 72 h on the ex‐pression of TRP‐1 ,but its role was not evident in the expression of TRP‐2 .308 nm excimer laser had effects both on TRP 1 and TRP 2 .Conclusion 308 nm excimer laser combination with piperine can increase the activation of amelanotic melanocytes in outer root sheath of hair .%目的:研究308nm激光联合胡椒碱对毛囊外根鞘无色素黑色素细胞(AMMC)黑色素合成及TRP‐1、TRP‐2蛋白表达的影响。方法体外培养的AMMC分为联合疗法组、308nm准分子激光组、胡椒碱组、阳性对照组及空白对照组,作用24、72、120h,测定黑色素水平,激光共聚焦显微镜观察并定量分析细胞内酪氨酸酶相关蛋白酶TRP‐1、TRP‐2的表达情况。结果联合治疗组、308nm准分子激光组、胡椒碱组、阳性对照组均不同程度地促进黑色素合成,其中以联合治疗组促进作用最强。联合治疗组和胡椒碱组的0.5mmol/L胡椒碱在72h内对黑色素水平促

  15. Pressure and gap length dependence of gap breakdown voltage and discharge current of discharge-pumped KrF excimer laser. Hoden reiki KrF laser no zetsuen hakai den prime atsu to reiki denryu no atsuryoku, gap cho izon sei

    Energy Technology Data Exchange (ETDEWEB)

    Yukimura, K.; Kawakami, H. (Doshisha Univ., Tokyo (Japan)); Hitomi, K. (Kyoto Polytechnic College, Kyoto (Japan))

    1991-04-20

    On the gap destruction characteristics of UV-preionized discharge-pumped KrF excimer laser (charge transfer type) and the electric characteristics of the excited discharge, studies were made by changing the pressure (1.5-3 atm) and the discharge gap length (14-21 mm) of the discharge medium. (1) Gap breakdown voltage and the maximum current of the excited discharge give a similarity by a product of pressure and the gap length at the charge volatge. (2) Insulation breakdown of the gap occurs at the wave front of the applied voltage and the breakdown time gets delayed by the decreasing voltage applied. By setting the ionization index at constant value 20, the gap breakdown voltage is estimated at the error within 10%. (3) The relation between the maximum current, pressure and the gap length product changes the characteristics by the charge voltage of the primary condenser. With the result combined with the standardization of voltage/current of the excited discharge, the electric characteristics at the specific pressure and gap length can be readily known. 10 refs., 10 figs.

  16. Pilot study of laser induced breakdown spectroscopy for tissue differentiation by monitoring the plume created during laser surgery — An approach on a feedback Laser control mechanism

    International Nuclear Information System (INIS)

    This study focuses on tissue differentiation using ‘Laser Induced Breakdown Spectroscopy’ (LIBS) by monitoring the plasma plume created during laser surgery processes. This technique is aimed at controlling a laser surgery feedback system in real time. An Excimer laser (Ar-F 193 nm) was used for the ablation of tissue samples. Fat, muscle, nerve and skin tissue samples of bisected ex-vivo pig heads were prepared as test objects for the ablation procedure. A single fiber was used to collect emissions and deliver them to a spectrometer. The obtained LIBS spectra in the measured emissions were analyzed to determine each tissue type according to their chemical composition. The elements found in the samples and their emission spectra were in agreement with those described in literature. The collected LIBS spectra were analyzed to differentiate the tissues using statistical data analysis: Principal Component Analysis (PCA), Linear Discriminant Analysis (LDA) and Receiver Operating Characteristics (ROC). The obtained preliminary results suggest a successful differentiation of the target tissues with high sensitivity and specificity. The main goal of this study was to qualitatively identify tissue types during laser ablation, which will provide a real time feedback mechanism for clinical Laser surgery applications to significantly improve the accuracy and safety of laser surgery procedures. - Graphical abstract: Skin, fat, muscle and nerve tissue differentiation. - Highlights: • Methods to differentiate tissues for the application in a laser surgery feedback control system • Successful differentiation of the target tissues with high sensitivity and specificity for laser surgery application • Real time feedback mechanism for clinical Laser surgery applications • Laser surgery requirements • Biomedical applications of LIBS

  17. Pilot study of laser induced breakdown spectroscopy for tissue differentiation by monitoring the plume created during laser surgery — An approach on a feedback Laser control mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Kanawade, Rajesh, E-mail: Rajesh.Kanawade@aot.uni-erlangen.de [Clinical Photonics Lab, Erlangen Graduate School in Advanced Optical Technologies (SAOT), Friedrich-Alexander-Universität Erlangen-Nürnberg, Paul-Gordan-Str. 6, 91052 Erlangen (Germany); Institute of Photonics Technologies, Friedrich-Alexander-Universität Erlangen-Nürnberg, Paul-Gordan-Str. 3, 91052 Erlangen (Germany); Mehari, Fanuel [Master Programme in Advanced Optical Technologies (MAOT), Friedrich-Alexander-Universität Erlangen-Nürnberg, Paul-Gordan-Str. 6, 91052 Erlangen (Germany); Knipfer, Christian; Rohde, Maximilian [Department of Oral and Maxillofacial Surgery, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Glueckstrasse 11, 91054 Erlangen (Germany); Tangermann-Gerk, Katja [Bayerisches Laserzentrum GmbH, Konrad-Zuse-Strasse 2-6, 91052 Erlangen (Germany); Schmidt, Michael [Clinical Photonics Lab, Erlangen Graduate School in Advanced Optical Technologies (SAOT), Friedrich-Alexander-Universität Erlangen-Nürnberg, Paul-Gordan-Str. 6, 91052 Erlangen (Germany); Institute of Photonics Technologies, Friedrich-Alexander-Universität Erlangen-Nürnberg, Paul-Gordan-Str. 3, 91052 Erlangen (Germany); Bayerisches Laserzentrum GmbH, Konrad-Zuse-Strasse 2-6, 91052 Erlangen (Germany); and others

    2013-09-01

    This study focuses on tissue differentiation using ‘Laser Induced Breakdown Spectroscopy’ (LIBS) by monitoring the plasma plume created during laser surgery processes. This technique is aimed at controlling a laser surgery feedback system in real time. An Excimer laser (Ar-F 193 nm) was used for the ablation of tissue samples. Fat, muscle, nerve and skin tissue samples of bisected ex-vivo pig heads were prepared as test objects for the ablation procedure. A single fiber was used to collect emissions and deliver them to a spectrometer. The obtained LIBS spectra in the measured emissions were analyzed to determine each tissue type according to their chemical composition. The elements found in the samples and their emission spectra were in agreement with those described in literature. The collected LIBS spectra were analyzed to differentiate the tissues using statistical data analysis: Principal Component Analysis (PCA), Linear Discriminant Analysis (LDA) and Receiver Operating Characteristics (ROC). The obtained preliminary results suggest a successful differentiation of the target tissues with high sensitivity and specificity. The main goal of this study was to qualitatively identify tissue types during laser ablation, which will provide a real time feedback mechanism for clinical Laser surgery applications to significantly improve the accuracy and safety of laser surgery procedures. - Graphical abstract: Skin, fat, muscle and nerve tissue differentiation. - Highlights: • Methods to differentiate tissues for the application in a laser surgery feedback control system • Successful differentiation of the target tissues with high sensitivity and specificity for laser surgery application • Real time feedback mechanism for clinical Laser surgery applications • Laser surgery requirements • Biomedical applications of LIBS.

  18. A Review of Auxin Response Factors (ARFs) in Plants

    Science.gov (United States)

    Li, Si-Bei; Xie, Zong-Zhou; Hu, Chun-Gen; Zhang, Jin-Zhi

    2016-01-01

    Auxin is a key regulator of virtually every aspect of plant growth and development from embryogenesis to senescence. Previous studies have indicated that auxin regulates these processes by controlling gene expression via a family of functionally distinct DNA-binding auxin response factors (ARFs). ARFs are likely components that confer specificity to auxin response through selection of target genes as transcription factors. They bind to auxin response DNA elements (AuxRE) in the promoters of auxin-regulated genes and either activate or repress transcription of these genes depending on a specific domain in the middle of the protein. Genetic studies have implicated various ARFs in distinct developmental processes through loss-of-function mutant analysis. Recent advances have provided information on the regulation of ARF gene expression, the role of ARFs in growth and developmental processes, protein–protein interactions of ARFs and target genes regulated by ARFs in plants. In particular, protein interaction and structural studies of ARF proteins have yielded novel insights into the molecular basis of auxin-regulated transcription. These results provide the foundation for predicting the contributions of ARF genes to the biology of other plants. PMID:26870066

  19. PH Domain-Arf G Protein Interactions Localize the Arf-GEF Steppke for Cleavage Furrow Regulation in Drosophila.

    Directory of Open Access Journals (Sweden)

    Donghoon M Lee

    Full Text Available The recruitment of GDP/GTP exchange factors (GEFs to specific subcellular sites dictates where they activate small G proteins for the regulation of various cellular processes. Cytohesins are a conserved family of plasma membrane GEFs for Arf small G proteins that regulate endocytosis. Analyses of mammalian cytohesins have identified a number of recruitment mechanisms for these multi-domain proteins, but the conservation and developmental roles for these mechanisms are unclear. Here, we report how the pleckstrin homology (PH domain of the Drosophila cytohesin Steppke affects its localization and activity at cleavage furrows of the early embryo. We found that the PH domain is necessary for Steppke furrow localization, and for it to regulate furrow structure. However, the PH domain was not sufficient for the localization. Next, we examined the role of conserved PH domain amino acid residues that are required for mammalian cytohesins to bind PIP3 or GTP-bound Arf G proteins. We confirmed that the Steppke PH domain preferentially binds PIP3 in vitro through a conserved mechanism. However, disruption of residues for PIP3 binding had no apparent effect on GFP-Steppke localization and effects. Rather, residues for binding to GTP-bound Arf G proteins made major contributions to this Steppke localization and activity. By analyzing GFP-tagged Arf and Arf-like small G proteins, we found that Arf1-GFP, Arf6-GFP and Arl4-GFP, but not Arf4-GFP, localized to furrows. However, analyses of embryos depleted of Arf1, Arf6 or Arl4 revealed either earlier defects than occur in embryos depleted of Steppke, or no detectable furrow defects, possibly because of redundancies, and thus it was difficult to assess how individual Arf small G proteins affect Steppke. Nonetheless, our data show that the Steppke PH domain and its conserved residues for binding to GTP-bound Arf G proteins have substantial effects on Steppke localization and activity in early Drosophila embryos.

  20. ArF short-pulse extraction studies. Final technical report, 18 September 1981-18 February 1983

    International Nuclear Information System (INIS)

    The experimental apparatus including e-beam pulse diagnostics is discussed. The relative fluorescence and laser output for various gas mixtures is presented and the significant improvement in laser performance for Ne buffered mixtures, allowing scaling to high pressures and high Joules per liter, is discussed. The energy deposition measurements for Ar and Ne buffered mixtures are presented. Accurate deposition measurements are necessary for a meaningful measure of the laser output efficiency. Background absorption measurements important for accessing the scalability of the ArF system are presented. The sidelight suppression experiments are discussed and the laser efficiency measurements are shown. Finally, a discussion of the measurements with their implications for the ArF system is presented in the concluding section

  1. Concept Framework for Audio Information Retrieval: ARF

    Institute of Scientific and Technical Information of China (English)

    LI GuoHui(李国辉); WU DeFeng(武德峰); ZHANG Jun(张军)

    2003-01-01

    The majority of researches on content-based retrieval focused on visual media.However audio is also an important medium and information carrier from the viewpoint of humanauditory perception, so it is needed to retrieve for audio collection. Audio is handled by conven-tional methods as an opaque stream medium, which is not suitable for information retrieval byits content. In fact, audio carries rich aural information with the form of speech, musical, andsound effects, so it could be retrieved based on its aural content, such as acoustic features, musicalmelodies and associated semantics. In this paper, a concept framework (ARF) for content-basedaudio retrieval is proposed from systematic perspectives, which describes audio content model,audio retrieval architecture and audio query schemes. Audio contents are represented by a hier-archical model and a set of formal descriptions from physical to acoustic to semantic level, whichdepict acoustic features, logical structure and semantics of audio and audio objects. The archi-tecture consisting of audio meta-database, populating and accessing modules presents a systemstructure view of audio information retrieval. The query schemes give generalized approaches andmodes concerning how users deliver audio information needs to audio collections. Finally, an audioretrieval example implemented is used to explain and specify the application of the components in the proposed ARF.

  2. Pulsed laser deposition of pepsin thin films

    Energy Technology Data Exchange (ETDEWEB)

    Kecskemeti, G. [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dom ter 9 (Hungary)]. E-mail: kega@physx.u-szeged.hu; Kresz, N. [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dom ter 9 (Hungary); Smausz, T. [Hungarian Academy of Sciences and University of Szeged, Research Group on Laser Physics, H-6720 Szeged, Dom ter 9 (Hungary); Hopp, B. [Hungarian Academy of Sciences and University of Szeged, Research Group on Laser Physics, H-6720 Szeged, Dom ter 9 (Hungary); Nogradi, A. [Department of Ophthalmology, University of Szeged, H-6720, Szeged, Koranyi fasor 10-11 (Hungary)

    2005-07-15

    Pulsed laser deposition (PLD) of organic and biological thin films has been extensively studied due to its importance in medical applications among others. Our investigations and results on PLD of a digestion catalyzing enzyme, pepsin, are presented. Targets pressed from pepsin powder were ablated with pulses of an ArF excimer laser ({lambda} = 193 nm, FWHM = 30 ns), the applied fluence was varied between 0.24 and 5.1 J/cm{sup 2}. The pressure in the PLD chamber was 2.7 x 10{sup -3} Pa. The thin layers were deposited onto glass and KBr substrates. Our IR spectroscopic measurements proved that the chemical composition of deposited thin films is similar to that of the target material deposited at 0.5 and 1.3 J/cm{sup 2}. The protein digesting capacity of the transferred pepsin was tested by adapting a modified 'protein cube' method. Dissolution of the ovalbumin sections proved that the deposited layers consisted of catalytically active pepsin.

  3. Direct initiation of the photopolymerization of acrylates by short-wavelength excimer UV radiation

    International Nuclear Information System (INIS)

    Investigations on the direct initiation of the photopolymerization of acrylates by irradiation with short-wavelength monochromatic UV light using the 222 nm emission of a KrCl* excimer lamp are reported. The reactivity of various acrylates was studied by real-time FTIR-ATR spectroscopy. Laser photolysis experiments and accompanying quantum chemical calculations were performed in order to propose a possible mechanism of initiation

  4. Excimer retreatment for scarring and regression after photorefractive keratectomy for myopia.

    OpenAIRE

    SUTTON, G; Kalski, R S; Lawless, M A; Rogers, C.

    1995-01-01

    AIMS/BACKGROUND--Scarring associated with regression of refractive effect can occur after photorefractive keratectomy (PRK) for myopia. The experience of treating these complications is reported. METHODS--Eighteen of 285 eyes (6.3%) were retreated with the excimer laser. Age, sex, preoperative primary treatment keratometry, pre-primary treatment, pre-retreatment and post-retreatment spherical equivalents, best corrected and uncorrected visual acuities were recorded and analysed. RESULTS--At 6...

  5. Applications of lasers in metallization of thermoplastic and thermosetting polymers

    Directory of Open Access Journals (Sweden)

    P. Rytlewski

    2013-04-01

    Full Text Available Purpose: This work focuses on the studies of chemical and physical changes induced by ArF-laser irradiation leading to formation of surfaces catalytically highly active and fully prepared for the direct electroless metallization for the case of thermoplastic and thermosetting polymer composites. The only pretreatment method for surface to be activated was laser irradiation. There are compared two polymer composites: thermoplastic and thermosetting with the same qualitative and quantitative contents of the selected copper compounds. Additionally, there is presented wide context of laser applications in electroless metallization of polymeric materials.Design/methodology/approach: The composites contained the same amount of copper(II oxide (CuO and copper(II acetoacetate Cu(acac2, while varied with the type of polymer matrix. There were chosen polyamide 6 as thermoplastic and polyurethane resin as thermosetting polymer matrixes. The composites were irradiated with various numbers of ArF excimer laser pulses (λ = 193 nm at constant fluence of 100 mJ/cm2. The metallization procedure of the laser-irradiated samples was performed by use of a commercial metallization bath and formaldehyde as a reducing agent. The samples were examined using FTIR, contact angle measurement and SEM techniques.Findings: It was found that laser irradiation induce catalytic properties in the studied composites. However, better catalytic properties were achieved for the thermoplastic than thermosetting polymer composites.Research limitations/implications: In order to better understand the differences in laser interactions between thermoplastic and thermosetting composites more examples of various polymer matrixes should be investigated.Practical implications: Suitable condition for laser irradiation of the composites associated with the best catalytic properties were proposes. Better catalytic properties were achieved for thermoplastic than thermosetting composite

  6. Bonded Excimer in Stacked Cytosines: A Semiclassical Simulation Study

    Directory of Open Access Journals (Sweden)

    Weifeng Wu

    2015-01-01

    Full Text Available The formation of a covalent bond between two stacked cytosines, one of which is excited by an ultrafast laser pulse, was studied by semiclassical dynamics simulations. The results show that a bonded excimer is created, which sharply lowers the energy gap between the LUMO and HOMO and consequently facilitates the deactivation of the electronically excited molecule. This is different from the case of two stacked adenines, where the formation of a covalent bond alters the nonadiabatic deactivation mechanism in two opposite ways. It lowers the energy gap and consequently leads to the coupling between the HOMO and LUMO levels, thus enhancing the deactivation of the electronically excited molecule. On the other hand, it leads to restriction of the deformation vibration of the pyrimidine in the excited molecule, because of a steric effect, and this delays the deactivation process of the excited adenine molecule with return to the electronic ground state.

  7. Advanced excimer-based crystallization systems for production solutions

    International Nuclear Information System (INIS)

    Line beam excimer laser annealing (ELA) is a well-known technique for thin Si-film crystallization and established in LTPS mass production. With introduction of sequential lateral solidification (SLS) some aspects such as crystalline quality, throughput and flexibility regarding the substrate size could be improved, but for OLED manufacturing still further process development is necessary. This paper discusses line beam ELA and SLS-techniques that might enable process engineers to make polycrystalline-silicon (poly-Si) films with a high degree of uniformity and quality as required for system on glass (SOG) and active matrix organic light emitting displays (AMOLED). Equipment requirements are discussed and compared to previous standards. SEM-images of process examples are shown in order to demonstrate the viability

  8. Advanced excimer-based crystallization systems for production solutions

    Energy Technology Data Exchange (ETDEWEB)

    Simon, F. [Lambda Physik AG, Goettingen (Germany)]. E-mail: frank.simon@coherent.com; Brune, J. [Lambda Physik AG, Goettingen (Germany); Herbst, L. [Lambda Physik AG, Goettingen (Germany)

    2006-04-30

    Line beam excimer laser annealing (ELA) is a well-known technique for thin Si-film crystallization and established in LTPS mass production. With introduction of sequential lateral solidification (SLS) some aspects such as crystalline quality, throughput and flexibility regarding the substrate size could be improved, but for OLED manufacturing still further process development is necessary. This paper discusses line beam ELA and SLS-techniques that might enable process engineers to make polycrystalline-silicon (poly-Si) films with a high degree of uniformity and quality as required for system on glass (SOG) and active matrix organic light emitting displays (AMOLED). Equipment requirements are discussed and compared to previous standards. SEM-images of process examples are shown in order to demonstrate the viability.

  9. SynArfGEF is a guanine nucleotide exchange factor for Arf6 and localizes preferentially at post-synaptic specializations of inhibitory synapses

    OpenAIRE

    Fukaya, M; Kamata, A.; Hara, Y; Tamaki, H.; Katsumata, O.; Ito, N.; Takeda, S.; Hata, Y; Suzuki, T.; Watanabe, M.(Niigata University, 950-2181, Niigata, Japan); Harvey, R J; Sakagami, H.

    2011-01-01

    SynArfGEF, also known as BRAG3 or IQSEC3, is a member of the brefeldin A-resistant Arf-GEF/IQSEC family and was originally identified by screening for mRNA species associated with the post-synaptic density fraction. In this study, we demonstrate that synArfGEF activates Arf6, using Arf pull down and transferrin incorporation assays. Immunohistochemical analysis reveals that synArfGEF is present in somata and dendrites as puncta in close association with inhibitory synapses, whereas immunoelec...

  10. 308nm准分子激光治疗对白癜风患者外周血Th1及Th2细胞因子的影响%Effect of 308nm excimer laser therapy on Th1/Th2 cytokines in peripheral blood of patients with vitiligo

    Institute of Scientific and Technical Information of China (English)

    李建英; 刘津民; 曹海育; 张玉红; 刘英权

    2014-01-01

    Objective To study the level of Th1 cytokine(IFN-γ) and Th2 cytokine (IL-4) in peripher-al blood of patients with vitiligo , and to explore the possible immune mechanism of 308 nm excimer laser for vitiligo therapy.Methods 50 cases of vitiligo were treated by 308nm excimer laser therapy , twice a week for 24 times.The level of IFN-γand IL-4 in peripheral blood from 50 vitiligo patients before and after treatment and 20 healthy per-son in control group were measured by enzyme linked immunosorbent assay .Results There was no difference be-tween two groups on the level of IL -4 (P>0.05).The level of IFN-γin vitiligo patients was higher than that in the control group (P0.05). Conclusion Th1 cytokine take advantage of vitiligo patients and involved in the pathogenesis of vitiligo .308nm ex-cimer laser therapy can restore the Th 1/Th2 balance .%目的:研究308 nm准分子激光对白癜风患者外周血Th1型细胞因子干扰素γ( IFN-γ)和Th2型细胞因子白细胞介素-4( IL-4)水平的影响,探讨其可能的作用机制。方法50例白癜风患者均采用308 nm准分子激光治疗,每周2次共治疗24次。采用酶联免疫吸附法( ELISA法)检测50例白癜风患者治疗前、后及20例正常健康者外周血IFN-γ及IL-4的水平,并统计临床疗效。结果治疗组治疗前IFN-γ水平较正常对照组升高,比较差异有统计学意义(P<0.05);治疗后较治疗前明显降低(P<0.05),且与正常对照组比较差异无统计学意义(P>0.05)。治疗组治疗前IL-4水平与正常对照组及本组治疗后比较差异均无统计学意义( P>0.05)。结论白癜风患者体内Th1型细胞因子占优势,308 nm准分子激光可恢复白癜风患者Th1及Th2的平衡状态。

  11. Fabrication of microlens array and bifocal microlens using the methods of laser ablation and solvent reflow

    Science.gov (United States)

    Yu, Cheng-Chian; Ho, Jeng-Rong

    2015-12-01

    Based on the techniques of laser microdrilling and solvent reflow, this study reports on a straightforward approach for fabricating plastic microlens arrays (MLAs). First, we use the ArF excimer laser to drill microholes on a polymethylmethacrylate plate for defining the lens number, initial depth, and diameter. The propylene glycol monomethyl ether acetate solvent is then employed to regulate the surface profile that leads to a resulting negative (concave) MLA. The corresponding positive (convex), polydimethyl-siloxane MLA is obtained by the soft-replica-molding technique. Through varying the pattern size and period on the mask and the light intensity for laser drilling and regulating the solvent in the reflow process, we exhibit the feasibility of making MLAs with various sizes and shapes. By modifying the laser ablation step to drill two microholes with different diameters and depths at two levels, we fabricate a bifocal microlens. The obtained microlenses have excellent surface and optical properties: surface roughness down to several nanometers and focal lengths varying from hundreds to thousands of micrometers. This approach is flexible for constructing microlenses with various sizes and shapes and can fabricate MLAs with a high fill factor.

  12. Germline CDKN2A/ARF alterations in human melanoma

    OpenAIRE

    Hashemi, Jamileh

    2002-01-01

    Approximately 10% of cases of human cutaneous malignant melanoma (CMM) have been estimated to occur in individuals with a familial predisposition, frequently in association with dysplastic nevus syndrome (DNS). The genetics of familial melanoma is complex and heterogeneous. To date only two melanoma predisposing genes have been identified. The CDKN2A/ARF locus on human chromosome 9p21 encodes two distinct cell cycle regulatory proteins, p16 and p14ARF. Germline alterations i...

  13. Utilizing dendritic scaffold for feasible formation of naphthalene excimer

    Indian Academy of Sciences (India)

    P K Lekha; Tufan Ghosh; Edamana Prasad

    2011-11-01

    Peripheral functionalization of PAMAM dendrimers with naphthalene units leads to significant ground state aggregation in the system above the critical aggregation concentrations (CAC). Upon photoexcitation of the ground state aggregates, static type excimer formation of naphthalene moiety is observed. Significant red-shifted emission from naphthalene excimers is achieved through generating the static type excimers in polar solvents such as methanol and acetonitrile-water mixtures. Control experiments suggest that the presence of dendritic scaffold in the system play a pivotal role in generating intense static excimer emission in naphthalene modified PAMAM dendrimers, in solution phase at room temperature.

  14. Lasers '92; Proceedings of the International Conference on Lasers and Applications, 15th, Houston, TX, Dec. 7-10, 1992

    Science.gov (United States)

    Wang, Charles P. (Editor)

    1993-01-01

    Papers from the conference are presented, and the topics covered include the following: x-ray lasers, excimer lasers, chemical lasers, high power lasers, blue-green lasers, dye lasers, solid state lasers, semiconductor lasers, gas and discharge lasers, carbon dioxide lasers, ultrafast phenomena, nonlinear optics, quantum optics, dynamic gratings and wave mixing, laser radar, lasers in medicine, optical filters and laser communication, optical techniques and instruments, laser material interaction, and industrial and manufacturing applications.

  15. SynArfGEF is a guanine nucleotide exchange factor for Arf6 and localizes preferentially at post-synaptic specializations of inhibitory synapses.

    Science.gov (United States)

    Fukaya, Masahiro; Kamata, Akifumi; Hara, Yoshinobu; Tamaki, Hideaki; Katsumata, Osamu; Ito, Naoki; Takeda, Shin'ichi; Hata, Yutaka; Suzuki, Tatsuo; Watanabe, Masahiko; Harvey, Robert J; Sakagami, Hiroyuki

    2011-03-01

    SynArfGEF, also known as BRAG3 or IQSEC3, is a member of the brefeldin A-resistant Arf-GEF/IQSEC family and was originally identified by screening for mRNA species associated with the post-synaptic density fraction. In this study, we demonstrate that synArfGEF activates Arf6, using Arf pull down and transferrin incorporation assays. Immunohistochemical analysis reveals that synArfGEF is present in somata and dendrites as puncta in close association with inhibitory synapses, whereas immunoelectron microscopic analysis reveals that synArfGEF localizes preferentially at post-synaptic specializations of symmetric synapses. Using yeast two-hybrid and pull down assays, we show that synArfGEF is able to bind utrophin/dystrophin and S-SCAM/MAGI-2 scaffolding proteins that localize at inhibitory synapses. Double immunostaining reveals that synArfGEF co-localizes with dystrophin and S-SCAM in cultured hippocampal neurons and cerebellar cortex, respectively. Both β-dystroglycan and S-SCAM were immunoprecipitated from brain lysates using anti-synArfGEF IgG. Taken together, these findings suggest that synArfGEF functions as a novel regulator of Arf6 at inhibitory synapses and associates with the dystrophin-associated glycoprotein complex and S-SCAM. PMID:21198641

  16. Plasma Generated During Pulsed Laser Deposition of Hydroxyapatite

    International Nuclear Information System (INIS)

    Plasma plume induced by laser ablation of a hydroxyapatite (Ca10(PO4)6(OH)2) target was studied in different ambient conditions. ArF excimer laser operated at the wavelength of 193 nm with the pulse energy of 300 mJ and 20 ns pulse duration. The emission spectra of the plasma plume were registered with the use of a fast gate, lens coupled micro-channel plate (MCP) image intensifier placed between a spectrograph and a CCD camera. The electron densities of 1023 divide 1022 m-3 were determined from the Stark broadening of the Ca I lines at distances 0.15- 2.5 cm from the target. Temperatures of 6.5 divide 3.5 kK at distances 1.9- 2.9 cm from the target were determined from the ratio of intensities of Ca lines. The expansion of the plasma plume was studied using the time of flight method. The time-dependent radiation of the Ca I and Ca II lines was registered with the use of a monochromator and photomultiplier in various distances from the target. Velocities of the order of 104 m/s were found. The dynamics of the plasma plume was also imaged by means of fast photography

  17. High-refractive-index fluids for the next-generation ArF immersion lithography

    Science.gov (United States)

    Wang, Yong; Miyamatsu, Takashi; Furukawa, Taiichi; Yamada, Kinji; Tominaga, Tetsuo; Makita, Yutaka; Nakagawa, Hiroki; Nakamura, Atsushi; Shima, Motoyuki; Kusumoto, Shiro; Shimokawa, Tsutomu; Hieda, Katsuhiko

    2006-03-01

    ArF immersion lithography using a high-refractive-index fluid (HIF) is considered to be a promising candidate for the 32nm node or below. At SPIE 2005 we introduced a new immersion fluid, JSR HIL-1, which has a refractive index and transmittance of 1.64 and >98%/mm (193.4nm, 23 °C), respectively. With HIL-1 immersion and a two beam interferometric exposure tool, hp32nm L/S imaging has been demonstrated. In this paper, we will report another novel immersion fluid, HIL-2, which has a transmittance of >99%/mm, which is almost as high as that of water, and a refractive index of 1.65 (193.4nm, 23 °C). Furthermore, an ArF laser irradiation study has shown that the degree of photodecomposition for both HIL-1 and HIL-2 is small enough for immersion lithography application. A "fluid puddle" defect study confirmed that HILs have less tendency to form immersion-specific photoresist defects and the refractive indices of HILs were found constant under laser irradiation. Batch-to-batch variation in refractive index during manufacture of HILs was not observed. By refining prism designs, hp30nm L/S patterns have also been successfully imaged with two interferometric exposure tools and HIL immersion.

  18. 308 nm准分子激光联合吡美莫司乳膏治疗儿童白癜风的疗效观察%Combination of 308 nm excimer laser with topical pimecrolimus cream for vitiligo in childhood

    Institute of Scientific and Technical Information of China (English)

    黄小晏; 杨慧兰; 樊建勇; 李雪梅

    2008-01-01

    Objective To assess the efficacy and safety of 308 nm excimer laser plus topical pimeevaluated after 15 and 30 times of laser therapy respectively.Results Except for one patient,all patients were able to be evaluated for effiicacy.After 30 times of laser therapy,the response and excellent response rates were 89.6%and 77.1%respectively,in group A,5.0%and 52.1%respectively in group B;both rates were significantly higher in group A than in group B(both P<0.05).Also,a highler repigmentation rate was obtained in facial lesions in group A compared with group B.Conclusions The 308 nm excimer laser is safe,erective and well-tolerated for vitiligo in childhood,and the combination with topical imecrolimus cream may improve its efficacy in facial vitiligo.%目的 评价308 nm准分子激光联合吡美莫司乳膏治疗儿童白癜风的疗效及不良反应.方法 随机选取49例皮损对称的稳定期儿童白癜风患者,采用自身对照方法 ,将对称的皮损随机分成A、B两组,A组:给予准分子激光照射,每周2次,疗程15周,联合外用吡美莫司乳膏,每日2次;B组:单独给予准分子激光照射,每周2次,疗程15周.分别于准分子激光治疗第15次及30次后进行疗效评价.结果 30次治疗结束后,A组显效率为77.1%,有效率为89.6%,B组显效率为52.1%,有效率为75.0%,A组有效率及显效率均显著优于B组(P=0.048,P=0.040).两组不同部位皮损疗效比较,仅面部皮损予以联合治疗后显效率及有效率显著优于单用准分子激光治疗(P=0.004).结论 308 nm准分子激光对儿童白癜风是一项安全、有效的治疗方法 ,联合应用吡美莫司乳膏能增加面部皮损疗效.

  19. Phenylethynylpyrene excimer forming hybridization probes for fluorescence SNP detection

    DEFF Research Database (Denmark)

    Prokhorenko, Igor A.; Astakhova, Irina V.; Momynaliev, Kuvat T.;

    2009-01-01

    Excimer formation is a unique feature of some fluorescent dyes (e.g., pyrene) which can be used for probing the proximity of biomolecules. Pyrene excimer fluorescence has previously been used for homogeneous detection of single nucleotide polymorphism (SNP) on DNA. 1-Phenylethynylpyrene (1-1-PEPy...

  20. Energy transfer from excimers of aromatic compounds to acylphosphine oxide

    International Nuclear Information System (INIS)

    Acylphosphine oxides were tested as a new class of singlet indicators and the diphenylphosphonyl radical was detected as a result of singlet energy transfer from excimers of benzene and its methyl-substituted derivatives to 2,4,6-trimethylbenzoyldiphenylphosphine oxide. G-values of singlet excimers and energy transfer rate constants were obtained and compared with the literature values. (author)

  1. One-pot synthesis and transfer of PMMA/Ag photonic nanocomposites by pulsed laser deposition

    Science.gov (United States)

    Karoutsos, V.; Koutselas, I.; Orfanou, P.; Mpatzaka, Th.; Vasileiadis, M.; Vassilakopoulou, A.; Vainos, N. A.; Perrone, A.

    2015-08-01

    Nanocomposite films comprising metallic nanoparticles in polymer matrices find increasing use in emerging photonic, electronic and microsystem applications owing to their tailored advanced functionalities. The versatile development of such films based on poly-methyl-methacrylate (PMMA) matrix having embedded Ag nanoparticles is addressed here. Two low-cost one-pot chemical methods for the synthesis of bulk target nanocomposite materials are demonstrated. These nanocomposites are subsequently transferred via pulsed laser deposition using 193 nm ArF excimer laser radiation, producing films maintaining the structural and functional properties. Both target- and laser-deposited materials have been thoroughly characterized using microscopic, spectroscopic and thermal analysis methods. Infrared spectra demonstrated the close molecular PMMA chain similarity for both target and film materials, though structural alterations identified by thermal analysis proved the enhanced characteristics of films grown. High-resolution electron microscopy proved the transfer of Ag nanoparticles sized 10-50 nm. Visible absorption peaked in the spectral range of 430-440 nm and attributed to the Ag nanocomposite plasmonic response verifying the transfer of the functional performance from target to film.

  2. Expression of the Arf tumor suppressor gene is controlled by Tgfβ2 during development

    Science.gov (United States)

    Freeman-Anderson, Natalie E.; Zheng, Yanbin; McCalla-Martin, Amy C.; Treanor, Louise M.; Zhao, Yi D.; Garfin, Phillip M.; He, Tong-Chuan; Mary, Michelle N.; Thornton, J. Derek; Anderson, Colleen; Gibbons, Melissa; Saab, Raya; Baumer, Shannon H.; Cunningham, John M.; Skapek, Stephen X.

    2009-01-01

    Summary The Arf tumor suppressor (also known as Cdkn2a) acts as an oncogene sensor induced by `abnormal' mitogenic signals in incipient cancer cells. It also plays a crucial role in embryonic development: newborn mice lacking Arf are blind due to a pathological process resembling severe persistent hyperplastic primary vitreous (PHPV), a human eye disease. The cell-intrinsic mechanism implied in the oncogene sensor model seems unlikely to explain Arf regulation during embryo development. Instead, transforming growth factor β2 (Tgfβ2) might control Arf expression, as we show that mice lacking Tgfβ2 have primary vitreous hyperplasia similar to Arf-/- mice. Consistent with a potential linear pathway, Tgfβ2 induces Arf transcription and p19Arf expression in cultured mouse embryo fibroblasts (MEFs); and Tgfβ2-dependent cell cycle arrest in MEFs is maintained in an Arf-dependent manner. Using a new model in which Arf expression can be tracked by β-galactosidase activity in ArflacZ/+ mice, we show that Tgfβ2 is required for Arf transcription in the developing vitreous as well as in the cornea and the umbilical arteries, two previously unrecognized sites of Arf expression. Chemical and genetic strategies show that Arf promoter induction depends on Tgfβ receptor activation of Smad proteins; the induction correlates with Smad2 phosphorylation in MEFs and Arf-expressing cells in vivo. Chromatin immunoprecipitation shows that Smads bind to genomic DNA proximal to Arf exon 1β. In summary, Tgfβ2 and p19Arf act in a linear pathway during embryonic development. We present the first evidence that p19Arf expression can be coupled to extracellular cues in normal cells and suggest a new mechanism for Arf control in tumor cells. PMID:19465598

  3. Cataractogenesis after Repeat Laser in situ Keratomileusis

    OpenAIRE

    Ahmad M. Mansour; Ghabra, Marwan

    2012-01-01

    There has been the unsubstantiated clinical impression that laser refractive surgery accelerates cataract development along with solid experimental data about the cataractogenic effects of excimer laser treatment. We present the first documented case of significant cataract formation in a young myope after repeat excimer laser ablation necessitating phacoemulsification with a posterior chamber implant. Proposed explanations include focusing of the ablation wave on the posterior capsule (acous...

  4. Semiclassical treatment of excimer spectral line shape for rare gas halides

    International Nuclear Information System (INIS)

    A great deal of work was done on the analysis of RgX emission spectra in the decade following the invention of the RgX lasers in 1975. However, high pressure KrI spectral data are still scarce and spectroscopy analysis of KrI spectra is not available. This paper reported the first spectroscopic study of the KrI excimers which agrees with the recent experimental work at high pressure. The spectral line shape was studied with a simple semiclassical model. This model provides semi-quantitative estimates for the governing potential functions associated with the ground and excited states. We compare our simulation results with experimental data of high-pressure KrI*, obtained in a novel 13.56 MHz excimer lamp system. This simulation yields the vibrational frequency of the KrI excited state, 132 cm-1, and the slope of the lower state potential curve in the Franck-Condon region, 0.035 Hartree/a0. In addition, factors that affect the line shapes of excimer spectra are discussed

  5. Semiclassical treatment of excimer spectral line shape for rare gas halides

    Science.gov (United States)

    Peng, S.; Delos, J. B.; Ametepe, J. D.; Manos, D. M.

    2007-03-01

    A great deal of work was done on the analysis of RgX emission spectra in the decade following the invention of the RgX lasers in 1975. However, high pressure KrI spectral data are still scarce and spectroscopy analysis of KrI spectra is not available. This paper reported the first spectroscopic study of the KrI excimers which agrees with the recent experimental work at high pressure. The spectral line shape was studied with a simple semiclassical model. This model provides semi-quantitative estimates for the governing potential functions associated with the ground and excited states. We compare our simulation results with experimental data of high-pressure KrI*, obtained in a novel 13.56 MHz excimer lamp system. This simulation yields the vibrational frequency of the KrI excited state, 132 cm-1, and the slope of the lower state potential curve in the Franck-Condon region, 0.035 Hartree/a0. In addition, factors that affect the line shapes of excimer spectra are discussed.

  6. Concentration, temperature, and density in a hydrogen-air flame by excimer-induced Raman scattering

    Science.gov (United States)

    Wehrmeyer, Joseph A.; Bowling, John M.; Pitz, Robert W.

    1988-01-01

    Single-pulse, vibrational Raman scattering (VRS) is an attractive laser diagnostic for the study of supersonic hydrogen-air combustion. The VRS technique gives a complete thermodynamic description of the gas mixture at a point in the reacting flow. Single-pulse, vibrational Raman scattering can simultaneously provide independent measurements of density, temperature, and concentration of each major species (H2, H2O, O2 and N2) in a hydrogen/air turbulent combustor. Also the pressure can be calculated using the ideal gas law. However, single-pulse VRS systems in current use for measurement of turbulent combustion have a number of shortcomings when applied to supersonic flows: (1) slow repetition rate (1 to 5 Hz), (2) poor spatial resolution (0.5x0.3x0.3 cu mm), and (3) marginal time resolution. Most of these shortcomings are due to the use of visible wavelength flash-lamp pumped dye lasers. The advent of UV excimer laser allows the possibility of dramatic improvements in the single-pulse, vibrational Raman scattering. The excimer based VRS probe will greatly improve repetition rate (100 to 500 Hz), spatial resolution (0.1x0.1x0.1 cu mm) and time resolution (30ns). These improvements result from the lower divergence of the UV excimer, higher repetition rate, and the increased Raman cross-sections (15 to 20 times higher) at ultra-violet (UV) wavelengths. With this increased capability, single-pulse vibrational Raman scattering promises to be an ideal non-intrusive probe for the study of hypersonic propulsion flows.

  7. Comparison of some effects of modification of a polylactide surface layer by chemical, plasma, and laser methods

    International Nuclear Information System (INIS)

    Highlights: • We modified polylactide surface layer with chemical, plasma or laser methods. • We tested selected properties and surface structure of modified samples. • We stated that the plasma treatment appears to be the most beneficial. - Abstract: The article presents the results of studies and comparison of selected properties of the modified PLA surface layer. The modification was carried out with three methods. In the chemical method, a 0.25 M solution of sodium hydroxide in water and ethanol was utilized. In the plasma method, a 50 W generator was used, which produced plasma in the air atmosphere under reduced pressure. In the laser method, a pulsed ArF excimer laser with fluency of 60 mJ/cm2 was applied. Polylactide samples were examined by using the following techniques: scanning electron microscopy (SEM), atomic force microscopy (AFM), goniometry and X-ray photoelectron spectroscopy (XPS). Images of surfaces of the modified samples were recorded, contact angles were measured, and surface free energy was calculated. Qualitative and quantitative analyses of chemical composition of the PLA surface layer were performed as well. Based on the survey it was found that the best modification results are obtained using the plasma method

  8. Comparison of some effects of modification of a polylactide surface layer by chemical, plasma, and laser methods

    Energy Technology Data Exchange (ETDEWEB)

    Moraczewski, Krzysztof, E-mail: kmm@ukw.edu.pl [Department of Materials Engineering, Kazimierz Wielki University, Department of Materials Engineering, ul. Chodkiewicza 30, 85-064 Bydgoszcz (Poland); Rytlewski, Piotr [Department of Materials Engineering, Kazimierz Wielki University, Department of Materials Engineering, ul. Chodkiewicza 30, 85-064 Bydgoszcz (Poland); Malinowski, Rafał [Institute for Engineering of Polymer Materials and Dyes, ul. M. Skłodowskiej–Curie 55, 87-100 Toruń (Poland); Żenkiewicz, Marian [Department of Materials Engineering, Kazimierz Wielki University, Department of Materials Engineering, ul. Chodkiewicza 30, 85-064 Bydgoszcz (Poland)

    2015-08-15

    Highlights: • We modified polylactide surface layer with chemical, plasma or laser methods. • We tested selected properties and surface structure of modified samples. • We stated that the plasma treatment appears to be the most beneficial. - Abstract: The article presents the results of studies and comparison of selected properties of the modified PLA surface layer. The modification was carried out with three methods. In the chemical method, a 0.25 M solution of sodium hydroxide in water and ethanol was utilized. In the plasma method, a 50 W generator was used, which produced plasma in the air atmosphere under reduced pressure. In the laser method, a pulsed ArF excimer laser with fluency of 60 mJ/cm{sup 2} was applied. Polylactide samples were examined by using the following techniques: scanning electron microscopy (SEM), atomic force microscopy (AFM), goniometry and X-ray photoelectron spectroscopy (XPS). Images of surfaces of the modified samples were recorded, contact angles were measured, and surface free energy was calculated. Qualitative and quantitative analyses of chemical composition of the PLA surface layer were performed as well. Based on the survey it was found that the best modification results are obtained using the plasma method.

  9. Laser ablation of human atherosclerotic plaque without adjacent tissue injury

    Science.gov (United States)

    Grundfest, W. S.; Litvack, F.; Forrester, J. S.; Goldenberg, T.; Swan, H. J. C.

    1985-01-01

    Seventy samples of human cadaver atherosclerotic aorta were irradiated in vitro using a 308 nm xenon chloride excimer laser. Energy per pulse, pulse duration and frequency were varied. For comparison, 60 segments were also irradiated with an argon ion and an Nd:YAG laser operated in the continuous mode. Tissue was fixed in formalin, sectioned and examined microscopically. The Nd:YAG and argon ion-irradiated tissue exhibited a central crater with irregular edges and concentric zones of thermal and blast injury. In contrast, the excimer laser-irradiated tissue had narrow deep incisions with minimal or no thermal injury. These preliminary experiments indicate that the excimer laser vaporizes tissue in a manner different from that of the continuous wave Nd:YAG or argon ion laser. The sharp incision margins and minimal damage to adjacent normal tissue suggest that the excimer laser is more desirable for general surgical and intravascular uses than are the conventionally used medical lasers.

  10. Excimer emission from pulsed microhollow cathode discharges in xenon

    OpenAIRE

    Lee, B.-J.; Rahman, H.; Nam, S. H.; Iberler, M.; J. Jacoby; Frank, Klaus

    2014-01-01

    Direct current (dc) microhollow cathode discharge (MHCD) is an intense source for excimer radiation in vacuum ultraviolet at a wavelength of 172 nm in a high pressure xenon (Xe) gas. The concentration of precursors for the excimer formation, i.e., excited and ionized gas atoms, increases significantly by applying high voltage pulse onto the dc MHCD over the pulse duration range from 20 to 100 ns. The intensity of the excimer emission for the voltage pulse of 20 ns duration exceeds that of the...

  11. Arf6 recruits the Rac GEF Kalirin to the plasma membrane facilitating Rac activation

    Directory of Open Access Journals (Sweden)

    Donaldson Julie G

    2007-07-01

    Full Text Available Abstract Background Many studies implicate Arf6 activity in Rac-mediated membrane ruffling and cytoskeletal reorganization. Although Arf6 facilitates the trafficking of Rac1 to the plasma membrane and in many cases Arf6 activation leads to the activation of Rac1, the details of how Arf6 influences Rac function remain to be elucidated. Results We demonstrate in binding assays and by co-immunoprecipitation that GDP-bound Arf6 binds to Kalirin5, a Rho family guanine nucleotide exchange factor, through interaction with the spectrin repeat region. In cells, expression of wild type Arf6 recruits spectrin repeat 5 and Kalirin to the plasma membrane and leads to enhanced Kalirin5-induced ruffling. By contrast, expression of an Arf6 mutant that cannot become activated, Arf6 T27N, still recruits spectrin repeat 5 and Kalirin to membranes but inhibits Kalirin5-induced ruffling in HeLa cells. Kalirin5-induced Rac1 activation is increased by the expression of wild type Arf6 and decreased by Arf6T27N. Furthermore, expression of a catalytically-inactive mutant of Kalirin5 inhibits cytoskeletal changes observed in cells expressing EFA6, an Arf6 guanine nucleotide exchange factor that leads to activation of Rac. Conclusion We show here with over-expressed proteins that the GDP-bound form of Arf6 can bind to the spectrin repeat regions in Kalirin Rho family GEFs thereby recruiting Kalirin to membranes. Although Kalirin is recruited onto membranes by Arf6-GDP, subsequent Rac activation and membrane ruffling requires Arf6 activation. From these results, we suggest that Arf6 can regulate through its GTPase cycle the activation of Rac.

  12. La0.7Sr0.3MnO3 thin films deposited by pulsed laser ablation for spintronic applications

    International Nuclear Information System (INIS)

    Among spintronic materials, mixed-valence manganite La0.7Sr0.3MnO3 (LSMO) is widely investigated due to its half-metal nature. LSMO thin films were grown by pulsed laser deposition (PLD) onto amorphous silica substrates heated at nearly 600 C. An ArF excimer laser was chosen to induce ablation due to its more energetic photons compared to the other quoted excimer laser sources. Different oxygen pressures were considered in order to study the influence of oxygen on the LSMO optical and electrical properties. In this respect, the visible transparency percentage of the deposited films is found good enough for spin-OLED applications. The absorption coefficient shows an absorption band tunable as a function of the oxygen content. Its energetic location and evolution with the oxygen content demonstrate it originates from radiative transitions between the spin-majority bands separated by the Jahn-Teller distortion. All of this lets relate the deposition oxygen pressure to the Mn3+ ion content in each film and interpret electrical data. The 200 and 100 nm thick samples exhibit weak metallic transport behavior at room temperature with a resistivity of 4.8 and 6.9 Ω cm, respectively. Concerning the resistivity response versus temperature, the measured low metal-insulator transition temperature (150 K) is related to the sample structural features as involved by the depositions. Two different transport mechanisms describe the conductivity regime of the deposited samples, namely the small polaron variable range hopping (VRH) and the Arrhenius law. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Production of porous PTFE-Ag composite thin films by pulsed laser deposition

    International Nuclear Information System (INIS)

    The suitability of pulsed laser deposition technique for preparation of polytetrafluoroethylene (PTFE) and silver (Ag) composite thin films was demonstrated. Disk-shaped targets combined from silver and Teflon with various percentages were ablated with pulses of an ArF excimer laser. The chemical composition of the deposited layers was estimated based on deposition rates determined for the pure PTFE and Ag films. EDX and SEM analyses using secondary electron and backscattered electron images proved that the morphology of the layers is determined by the PTFE which is the main constituent and it is transferred mostly in form of grains and clusters forming a sponge-like structure with high specific surface. The Ag content is distributed over the surface of the PTFE structure. Contact angle measurements showed that with increasing the amount of Ag in the deposited layers the surface significantly enhanced the wetting properties. Conductivity experiments demonstrated that when the average silver content of the layers was increased from 0.16 to 3.28 wt% the resistance of our PTFE-Ag composite films decreased with about three orders of magnitudes (from ∼10 MΩ to ∼10 kΩ). The properties of these films suggest as being a good candidate for future electrochemical sensor applications.

  14. Investigation of pulsed laser deposited crystalline PTFE thin layer with pulsed force mode AFM

    International Nuclear Information System (INIS)

    Teflon thin films were prepared via pulsed laser deposition using an ArF excimer laser (λ=193 nm, FWHM=20 ns) from pressed powder pellets. The applied fluence was 6.25±0.23 J/cm2, the number of pulses was 10 000, the pressure in the vacuum chamber was 2x10-5 Torr and the substrate temperature was 250 deg. C. The layers were post-annealed at temperature within the range 320-500 deg. C. The atomic force microscopy and pulsed force mode atomic force microscopy (PFM) investigations demonstrated that the effective surface reaches its maximum at 320 deg. C. At higher temperatures (360-500 deg. C) it decreased significantly to an approximately constant value. Measuring the local adhesion the difference between the adhesion forces at 320 and 360 deg. C was kept within the error range. Increasing the annealing temperatures, the adhesion force decreased over the investigated range. Post-annealing of the samples at 360 deg. C resulted in highly crystalline spherulites with lateral dimensions of several hundred micrometers. By optimizing the heating and cooling rate during the annealing the average dimension of spherulites increased and ringed structures were obtained. The PFM measurements showed that the adhesion force increased significantly compared to the similar samples without ringed structures

  15. Permanent excimer superstructures by supramolecular networking of metal quantum clusters

    Science.gov (United States)

    Santiago-Gonzalez, Beatriz; Monguzzi, Angelo; Azpiroz, Jon Mikel; Prato, Mirko; Erratico, Silvia; Campione, Marcello; Lorenzi, Roberto; Pedrini, Jacopo; Santambrogio, Carlo; Torrente, Yvan; De Angelis, Filippo; Meinardi, Francesco; Brovelli, Sergio

    2016-08-01

    Excimers are evanescent quasi-particles that typically form during collisional intermolecular interactions and exist exclusively for their excited-state lifetime. We exploited the distinctive structure of metal quantum clusters to fabricate permanent excimer-like colloidal superstructures made of ground-state noninteracting gold cores, held together by a network of hydrogen bonds between their capping ligands. This previously unknown aggregation state of matter, studied through spectroscopic experiments and ab initio calculations, conveys the photophysics of excimers into stable nanoparticles, which overcome the intrinsic limitation of excimers in single-particle applications—that is, their nearly zero formation probability in ultra-diluted solutions. In vitro experiments demonstrate the suitability of the superstructures as nonresonant intracellular probes and further reveal their ability to scavenge reactive oxygen species, which enhances their potential as anticytotoxic agents for biomedical applications.

  16. [Laser treatment of urethral strictures].

    Science.gov (United States)

    Klammert, R; Schneede, P; Kriegmair, M

    1994-07-01

    Since the late 1970s different laser systems have been applied for the treatment of urethral strictures. Thermal effects adjacent on tissue have made the long term results of Nd:-YAG and Ar+ laser application discouraging. New laser systems (KTP, Excimer, Ho: YAG) still have to prove their efficacy in randomized clinical trials against cold knife urethrotomy. PMID:7941175

  17. New laser research and development

    International Nuclear Information System (INIS)

    New types of lasers must be developed to provide the desired energy per pulse, pulse length, pulse shape, wavelength, and efficiency for laser-fusion applications. This advanced laser research has focused on rare-gas oxides and on Hg2 excimers

  18. Direct initiation of the photopolymerization of acrylates by 222 nm excimer UV radiation

    International Nuclear Information System (INIS)

    Complete text of publication follows. Usually, the photopolymerisation of functionalised monomers and oligomers requires the addition of one or several photoinitiators to the formulation. The light of typically used mercury lamps (1>250 nm) is mainly absorbed by the photoinitiator leading to initiating species (radicals) with a high quantum yield. The introduction of excimer lamps as monochromatic UV sources with an intense short-wavelength emission opens up new possibilities for a photoinitiator-free initiation of the acrylate polymerisation. Like most other organic compounds, acrylates strongly absorb light with a wavelength shorter than about 220 to 240 nm, and they can therefore be directly excited by the 222 nm excimer radiation from a KrCl* lamp. Real-time FTIR-ATR spectroscopy was used to study the reactivity of various neat acrylates. Depending on the absorption coefficient, aliphatic acrylates can be cured up to a thickness of several microns whereas for highly absorbing aromatic acrylates, the depth of cure reaches only some hundred nanometres. Since the radical yield is low, photopolymerisation without photoinitiator has to be performed in an inert atmosphere. Laser photolysis experiments were carried out with a KrCl* excimer laser (pulse width 20 ns, up to 5 mJ per pulse) to investigate the primary processes of the direct initiation. Additionally, quantum chemical calculations were performed to assist the interpretation of the photolysis data. For all acrylates studied, direct excitation at 222 nm first leads to the formation of a triplet state which is highly localized at the vinyl double bond (and not at the carbonyl group). This triplet state may undergo different reactions like inter- and intramolecular hydrogen transfer and biradical formation as well as the addition to a ground state molecule (chain start). Our current interpretation of the experimental results and the quantum chemical calculations will be presented and discussed

  19. Development of Nanosecond Short Pulse High Power KrF Laser System

    Institute of Scientific and Technical Information of China (English)

    SZATMAR; Sador; BOHUS; Janos

    2011-01-01

    Compression of short pulse laser is demanded by the physical experiments such as EOS for Heaven-I system. A nanosecond short pulse high power discharge pumping excimer laser system was developed under the frame of Science and Technology

  20. Comparison of some effects of modification of a polylactide surface layer by chemical, plasma, and laser methods

    Science.gov (United States)

    Moraczewski, Krzysztof; Rytlewski, Piotr; Malinowski, Rafał; Żenkiewicz, Marian

    2015-08-01

    The article presents the results of studies and comparison of selected properties of the modified PLA surface layer. The modification was carried out with three methods. In the chemical method, a 0.25 M solution of sodium hydroxide in water and ethanol was utilized. In the plasma method, a 50 W generator was used, which produced plasma in the air atmosphere under reduced pressure. In the laser method, a pulsed ArF excimer laser with fluency of 60 mJ/cm2 was applied. Polylactide samples were examined by using the following techniques: scanning electron microscopy (SEM), atomic force microscopy (AFM), goniometry and X-ray photoelectron spectroscopy (XPS). Images of surfaces of the modified samples were recorded, contact angles were measured, and surface free energy was calculated. Qualitative and quantitative analyses of chemical composition of the PLA surface layer were performed as well. Based on the survey it was found that the best modification results are obtained using the plasma method.

  1. Optical performance of thin films produced by the pulsed laser deposition of SiAlON and Er targets

    International Nuclear Information System (INIS)

    Highlights: • PLD production of Er-doped thin films from a low cost commercial SiAlON target. • The role of the ablation fluence on the composition, optical properties as well as on the light emission performance at 1.5 μm. • The optimized performance is obtained for the samples deposited at the higher used ablation energy density. Further improvement was achieved through annealing. - Abstract: We report the preparation and optical performance of thin films produced by pulsed laser deposition in vacuum at room temperature, by focusing an ArF excimer laser onto two separate targets: a commercial ceramic SiAlON and a metallic Er target. As a result of the alternate deposition Er:SiAlON films were formed. The as grown films exhibited an Er-related emission peaking at 1532 nm. The role of the PLD energy density during deposition on the final matrix film was investigated, in order to achieve an optimized matrix composition with enhanced optical properties, and its effect on the light emission performance

  2. Optical performance of thin films produced by the pulsed laser deposition of SiAlON and Er targets

    Energy Technology Data Exchange (ETDEWEB)

    Camps, I., E-mail: camps@io.cfmac.csic.es [Laser Processing Group, Instituto de Óptica, CSIC, C/Serrano 121, 28006 Madrid (Spain); Ramírez, J.M. [MIND-IN2UB, Departament d’Electrònica, Universitat de Barcelona, c/Martí i Franqués 1, 08028 Barcelona (Spain); Mariscal, A.; Serna, R. [Laser Processing Group, Instituto de Óptica, CSIC, C/Serrano 121, 28006 Madrid (Spain); Garrido, B. [MIND-IN2UB, Departament d’Electrònica, Universitat de Barcelona, c/Martí i Franqués 1, 08028 Barcelona (Spain); Perálvarez, M.; Carreras, J. [IREC, Fundació Privada Institut de Recerca en Energia de Catalunya (Spain); Barradas, N.P.; Alves, L.C. [C" 2TN, Instituto Superior Técnico, Universidade de Lisboa, E.N. 10, 2695-066 Bobadela (Portugal); Alves, E. [IPFN, Instituto Superior Técnico, Universidade de Lisboa, E.N. 10, 2695-066 Bobadela (Portugal)

    2015-05-01

    Highlights: • PLD production of Er-doped thin films from a low cost commercial SiAlON target. • The role of the ablation fluence on the composition, optical properties as well as on the light emission performance at 1.5 μm. • The optimized performance is obtained for the samples deposited at the higher used ablation energy density. Further improvement was achieved through annealing. - Abstract: We report the preparation and optical performance of thin films produced by pulsed laser deposition in vacuum at room temperature, by focusing an ArF excimer laser onto two separate targets: a commercial ceramic SiAlON and a metallic Er target. As a result of the alternate deposition Er:SiAlON films were formed. The as grown films exhibited an Er-related emission peaking at 1532 nm. The role of the PLD energy density during deposition on the final matrix film was investigated, in order to achieve an optimized matrix composition with enhanced optical properties, and its effect on the light emission performance.

  3. STAT3 regulated ARF expression suppresses prostate cancer metastasis

    Science.gov (United States)

    Pencik, Jan; Schlederer, Michaela; Gruber, Wolfgang; Unger, Christine; Walker, Steven M.; Chalaris, Athena; Marié, Isabelle J.; Hassler, Melanie R.; Javaheri, Tahereh; Aksoy, Osman; Blayney, Jaine K.; Prutsch, Nicole; Skucha, Anna; Herac, Merima; Krämer, Oliver H.; Mazal, Peter; Grebien, Florian; Egger, Gerda; Poli, Valeria; Mikulits, Wolfgang; Eferl, Robert; Esterbauer, Harald; Kennedy, Richard; Fend, Falko; Scharpf, Marcus; Braun, Martin; Perner, Sven; Levy, David E.; Malcolm, Tim; Turner, Suzanne D.; Haitel, Andrea; Susani, Martin; Moazzami, Ali; Rose-John, Stefan; Aberger, Fritz; Merkel, Olaf; Moriggl, Richard; Culig, Zoran; Dolznig, Helmut; Kenner, Lukas

    2015-01-01

    Prostate cancer (PCa) is the most prevalent cancer in men. Hyperactive STAT3 is thought to be oncogenic in PCa. However, targeting of the IL-6/STAT3 axis in PCa patients has failed to provide therapeutic benefit. Here we show that genetic inactivation of Stat3 or IL-6 signalling in a Pten-deficient PCa mouse model accelerates cancer progression leading to metastasis. Mechanistically, we identify p19ARF as a direct Stat3 target. Loss of Stat3 signalling disrupts the ARF–Mdm2–p53 tumour suppressor axis bypassing senescence. Strikingly, we also identify STAT3 and CDKN2A mutations in primary human PCa. STAT3 and CDKN2A deletions co-occurred with high frequency in PCa metastases. In accordance, loss of STAT3 and p14ARF expression in patient tumours correlates with increased risk of disease recurrence and metastatic PCa. Thus, STAT3 and ARF may be prognostic markers to stratify high from low risk PCa patients. Our findings challenge the current discussion on therapeutic benefit or risk of IL-6/STAT3 inhibition. PMID:26198641

  4. Beam Positioning Error Budget of Angular Multiplexing Excimer Master Osillator Power-Amplifier Laser System%角多路准分子激光主振荡器功率放大系统光束定位误差分配

    Institute of Scientific and Technical Information of China (English)

    王大辉; 赵军; 赵学庆; 黄珂; 孙昱薇; 张永生; 郑国鑫; 胡云

    2011-01-01

    Angular multiplexing excimer master oscillator power-amplifier laser (MOPA) system is simplified by object-image conjugate structure. Relations between the drifts of optical components and the deviation of corresponding imaging plane are derived by transfer matrix and ray tracing. The index weight is determined by improved analytic hierarchy process according to nine scale evaluation matrix, and the beam positioning stability requirement of optical components which affects system stability is acquired. Results show that the error budget values of optical components is related to the focus of image-relaying and the distance from object plane. The values change conversely with the focuses. The optical components stability in laboratory environment is measured and compared with those of error budget.%对角多路准分子激光主振荡器功率放大(MOPA)系统进行物像共轭结构简化.利用传输矩阵和光线追迹,推导出了像传递光路中光学元件扰动与相应像面光束定位误差之间关系式.根据九标度赋值矩阵,采用改进层次分析法确定指标权重系数,得到了影响系统稳定性的光学元件光束定位指标要求.结果表明,光学元件分配指标大小和像传递结构焦距、光学元件(反射镜)距离像传递结构物面距离有关,焦距越大指标越小,距离越远指标越大.测量了实验室环境下光学元件的稳定性,对测量结果和定位误差进行了分析,并在此基础上提出了光路设计和光路优化的建议.

  5. Laser in ophthalmology. Laser i oftalmologien

    Energy Technology Data Exchange (ETDEWEB)

    Syrdalen, P. (Rikshospitalet, Oslo (Norway))

    1991-09-01

    The article presents a brief history of the use of laser in ophthalmology in Norway, from the introduction of the first argon-photocoalulator in 1972 to the excimer laser in 1990. The argon-photocoagulator is in daily us in all Eye Departments in Norway and the main group of patients treated are those with diabetic retionopathy. Glaucoma has been treated with argon-laser with good results for the last ten years. YAG-laser, introduced in Norway in 1985, is used to treat secondary cataracts which occur after extracapsular cataract extractions and implantation of artificial lenses. In 1990, the excimer laser was introduced for refractive surgery (myopia, astigmatism). 4 refs., 6 figs., 1 tab.

  6. A role for Arf1 in mitotic Golgi disassembly, chromosome segregation, and cytokinesis

    OpenAIRE

    Altan-Bonnet, Nihal; Phair, Robert D.; Polishchuk, Roman S.; Weigert, Roberto; Lippincott-Schwartz, Jennifer

    2003-01-01

    In mitosis, chromosome, cytoskeleton, and organelle dynamics must be coordinated for successful cell division. Here, we present evidence for a role for Arf1, a small GTPase associated with the Golgi apparatus, in the orchestration of mitotic Golgi breakdown, chromosome segregation, and cytokinesis. We show that early in mitosis Arf1 becomes inactive and dissociates from Golgi membranes. This is followed by the dispersal of numerous Arf1-dependent peripheral Golgi proteins and subsequent Golgi...

  7. Ultraviolet SO lasers optically pumped by a tunable, line-narrowed KrF laser

    International Nuclear Information System (INIS)

    The feasibility of an ultraviolet energy storage laser based on the long-lived sulfur monoxide A3π-χ3Σ- electronic transition was investigated, and an ultraviolet laser based on the short-lived SO(B3 Σ--χ3Σ-) transition was demonstrated and modeled. Both were optically pumped by a continuously tunable, line-narrowed KrF laser developed for efficient rotationally resolved excitation of SO. SO was produced by both microwave discharge and excimer laser photolysis of the precursor molecules SO2 and SOCl2, with a maximum SO concentration (1016 cm-3) generated by ArF (193 nm) photodissociation of SO2. Laser induced fluorescence of SO was used to study the excitation spectroscopy, vibrational branching ratios, lifetimes and deactivation rates. The radiative lifetime of SO(A3π2,v' = 5) was measured to be 6.9 μs and that of SO(B,v' = 1) to be 33 ns. Lifetimes in the highly perturbed SO(B,v' = 2) level ranged from 28--90 ns. Measurements and modeling of the excitation saturation fluence as a function of buffer gas pressure determined what fraction of the ground state SO(X) molecules could be excited to SO(A) or SO(B). No evidence of excited state absorption was seen. Lasing on six new ultraviolet SO(B-X) vibrational bands in the range 262--315 nm was demonstrated. SO(B-X) pulse energies of up to 11 μJ were obtained and the gain coefficient was estimated to be 0.1 cm-1. A multi-level rate equation model of the SO(B-X) excitation and lasing transitions, including collisional rotational mixing, described the dynamics of the lasing and measured output very well. Modeling showed and experiments confirmed that the maximum possible SO laser gain simply corresponded to saturating the excitation of a single rotational level. Collisional coupling of the rotational levels increased the laser output energy

  8. Theoretical investigation of perylene dimers and excimers and their signatures in X-ray diffraction

    DEFF Research Database (Denmark)

    Velardez, Gustavo; Lemke, H. T.; Breiby, D.W.; Nielsen, Martin Meedom; Møller, Klaus Braagaard; Henriksen, Niels Engholm

    2008-01-01

    the concentration of excimers in a crystal. The intensity of the 110, 005, and 0 10 0 reflections are found to be fairly sensitive to the presence of excimers in the crystal. The finite (nanosecond) lifetime of the excimer may make it possible to observe this state using time-resolved X-ray...

  9. Overexpression of AtTTP Affects ARF17 Expression and Leads to Male Sterility in Arabidopsis

    OpenAIRE

    Zhi-Hao Shi; Cheng Zhang; Xiao-Feng Xu; Jun Zhu; Que Zhou; Li-Juan Ma; Jin Niu; Zhong-Nan Yang

    2015-01-01

    Callose synthesis is critical for the formation of the pollen wall pattern. CalS5 is thought to be the major synthethase for the callose wall. In the Arabidopsis anther, ARF17 regulates the expression of CalS5 and is the target of miR160. Plants expressing miR160-resistant ARF17 (35S:5mARF17 lines) with increased ARF17 mRNA levels display male sterility. Here we report a zinc finger family gene, AtTTP, which is involved in miR160 maturation and callose synthesis in Arabidopsis. AtTTP is expre...

  10. The Guanine Nucleotide Exchange Factor ARNO mediates the activation of ARF and phospholipase D by insulin

    Directory of Open Access Journals (Sweden)

    Fluharty Eric

    2003-09-01

    Full Text Available Abstract Background Phospholipase D (PLD is involved in many signaling pathways. In most systems, the activity of PLD is primarily regulated by the members of the ADP-Ribosylation Factor (ARF family of GTPases, but the mechanism of activation of PLD and ARF by extracellular signals has not been fully established. Here we tested the hypothesis that ARF-guanine nucleotide exchange factors (ARF-GEFs of the cytohesin/ARNO family mediate the activation of ARF and PLD by insulin. Results Wild type ARNO transiently transfected in HIRcB cells was translocated to the plasma membrane in an insulin-dependent manner and promoted the translocation of ARF to the membranes. ARNO mutants: ΔCC-ARNO and CC-ARNO were partially translocated to the membranes while ΔPH-ARNO and PH-ARNO could not be translocated to the membranes. Sec7 domain mutants of ARNO did not facilitate the ARF translocation. Overexpression of wild type ARNO significantly increased insulin-stimulated PLD activity, and mutations in the Sec7 and PH domains, or deletion of the PH or CC domains inhibited the effects of insulin. Conclusions Small ARF-GEFs of the cytohesin/ARNO family mediate the activation of ARF and PLD by the insulin receptor.

  11. Genomewide identification and expression analysis of the ARF gene family in apple

    Indian Academy of Sciences (India)

    Xiao-Cui Luo; Mei-Hong Sun; Rui-Rui Xu; Huai-Rui Shu; Jai-Wei Wang; Shi-Zhong Zhang

    2014-12-01

    Auxin response factors (ARF) are transcription factors that regulate auxin responses in plants. Although the genomewide analysis of this family has been performed in some species, little is known regarding ARF genes in apple (Malus domestica). In this study, 31 putative apple ARF genes have been identified and located within the apple genome. The phylogenetic analysis revealed that MdARFs could be divided into three subfamilies (groups I, II and III). The predicted MdARFs were distributed across 15 of 17 chromosomes with different densities. In addition, the analysis of exon–intron junctions and of the intron phase inside the predicted coding region of each candidate gene has revealed high levels of conservation within and between phylogenetic groups. Expression profile analyses of MdARF genes were performed in different tissues (root, stem, leaf, flower and fruit), and all the selected genes were expressed in at least one of the tissues that were tested, which indicated that MdARFs are involved in various aspects of physiological and developmental processes of apple. To our knowledge, this report is the first to provide a genomewide analysis of the apple ARF gene family. This study provides valuable information for understanding the classification and putative functions of the ARF signal in apple.

  12. Genome-wide identification and expression profiling of auxin response factor (ARF gene family in maize

    Directory of Open Access Journals (Sweden)

    Zhang Yirong

    2011-04-01

    Full Text Available Abstract Background Auxin signaling is vital for plant growth and development, and plays important role in apical dominance, tropic response, lateral root formation, vascular differentiation, embryo patterning and shoot elongation. Auxin Response Factors (ARFs are the transcription factors that regulate the expression of auxin responsive genes. The ARF genes are represented by a large multigene family in plants. The first draft of full maize genome assembly has recently been released, however, to our knowledge, the ARF gene family from maize (ZmARF genes has not been characterized in detail. Results In this study, 31 maize (Zea mays L. genes that encode ARF proteins were identified in maize genome. It was shown that maize ARF genes fall into related sister pairs and chromosomal mapping revealed that duplication of ZmARFs was associated with the chromosomal block duplications. As expected, duplication of some ZmARFs showed a conserved intron/exon structure, whereas some others were more divergent, suggesting the possibility of functional diversification for these genes. Out of these 31 ZmARF genes, 14 possess auxin-responsive element in their promoter region, among which 7 appear to show small or negligible response to exogenous auxin. The 18 ZmARF genes were predicted to be the potential targets of small RNAs. Transgenic analysis revealed that increased miR167 level could cause degradation of transcripts of six potential targets (ZmARF3, 9, 16, 18, 22 and 30. The expressions of maize ARF genes are responsive to exogenous auxin treatment. Dynamic expression patterns of ZmARF genes were observed in different stages of embryo development. Conclusions Maize ARF gene family is expanded (31 genes as compared to Arabidopsis (23 genes and rice (25 genes. The expression of these genes in maize is regulated by auxin and small RNAs. Dynamic expression patterns of ZmARF genes in embryo at different stages were detected which suggest that maize ARF genes may

  13. Arf4 is required for Mammalian development but dispensable for ciliary assembly.

    Directory of Open Access Journals (Sweden)

    John A Follit

    2014-02-01

    Full Text Available The primary cilium is a sensory organelle, defects in which cause a wide range of human diseases including retinal degeneration, polycystic kidney disease and birth defects. The sensory functions of cilia require specific receptors to be targeted to the ciliary subdomain of the plasma membrane. Arf4 has been proposed to sort cargo destined for the cilium at the Golgi complex and deemed a key regulator of ciliary protein trafficking. In this work, we show that Arf4 binds to the ciliary targeting sequence (CTS of fibrocystin. Knockdown of Arf4 indicates that it is not absolutely required for trafficking of the fibrocystin CTS to cilia as steady-state CTS levels are unaffected. However, we did observe a delay in delivery of newly synthesized CTS from the Golgi complex to the cilium when Arf4 was reduced. Arf4 mutant mice are embryonic lethal and die at mid-gestation shortly after node formation. Nodal cilia appeared normal and functioned properly to break left-right symmetry in Arf4 mutant embryos. At this stage of development Arf4 expression is highest in the visceral endoderm but we did not detect cilia on these cells. In the visceral endoderm, the lack of Arf4 caused defects in cell structure and apical protein localization. This work suggests that while Arf4 is not required for ciliary assembly, it is important for the efficient transport of fibrocystin to cilia, and also plays critical roles in non-ciliary processes.

  14. Synthesis of diamondlike carbon particles in/on a water substrate by laser irradiation

    International Nuclear Information System (INIS)

    We proposed two-particle synthesis techniques using a liquid as a substrate. First, utilizing liquid instead of solid substrates, particle synthesis is expected on the liquid surface. Particles sink into the liquid before the particles grow into film, because of liquid fluidity. Second, the excitation of a gas dissolved in water was also attempted. An ArF excimer laser beam was focused in a chamber. The 60% volume of the chamber was filled with water, in which methane was dissolved and the remaining space of the chamber was filled with methane gas. As a result, diamondlike carbon particles could be synthesized in water. The particles synthesized from methane in the gas phase were 50-200 nm in diameter, and the particles synthesized from methane dissolved in water were 200-700 nm in diameter, and no structural differences were observed between the particles of two different diameters. Energy-dispersive spectroscopy, Raman spectroscopy analysis, and high-resolution transmission electron microscopy observations revealed that particles contained a diamondlike carbon component and that graphite was attached to them. These particles were harder than graphite particles

  15. Expression of arf tumor suppressor in spermatogonia facilitates meiotic progression in male germ cells.

    Directory of Open Access Journals (Sweden)

    Michelle L Churchman

    2011-07-01

    Full Text Available The mammalian Cdkn2a (Ink4a-Arf locus encodes two tumor suppressor proteins (p16(Ink4a and p19(Arf that respectively enforce the anti-proliferative functions of the retinoblastoma protein (Rb and the p53 transcription factor in response to oncogenic stress. Although p19(Arf is not normally detected in tissues of young adult mice, a notable exception occurs in the male germ line, where Arf is expressed in spermatogonia, but not in meiotic spermatocytes arising from them. Unlike other contexts in which the induction of Arf potently inhibits cell proliferation, expression of p19(Arf in spermatogonia does not interfere with mitotic cell division. Instead, inactivation of Arf triggers germ cell-autonomous, p53-dependent apoptosis of primary spermatocytes in late meiotic prophase, resulting in reduced sperm production. Arf deficiency also causes premature, elevated, and persistent accumulation of the phosphorylated histone variant H2AX, reduces numbers of chromosome-associated complexes of Rad51 and Dmc1 recombinases during meiotic prophase, and yields incompletely synapsed autosomes during pachynema. Inactivation of Ink4a increases the fraction of spermatogonia in S-phase and restores sperm numbers in Ink4a-Arf doubly deficient mice but does not abrogate γ-H2AX accumulation in spermatocytes or p53-dependent apoptosis resulting from Arf inactivation. Thus, as opposed to its canonical role as a tumor suppressor in inducing p53-dependent senescence or apoptosis, Arf expression in spermatogonia instead initiates a salutary feed-forward program that prevents p53-dependent apoptosis, contributing to the survival of meiotic male germ cells.

  16. Abnormalities of the ARF-p53 pathway in primary angiosarcomas of the liver.

    Science.gov (United States)

    Weihrauch, Markus; Markwarth, Anett; Lehnert, Gerhard; Wittekind, Christian; Wrbitzky, Renate; Tannapfel, Andrea

    2002-09-01

    The INK4a-ARF locus, located on chromosome 9p21, encodes 2 cell cycle-regulatory proteins, p16(INKa) and p14(ARF), acting through the Rb-CDK4 and p53 pathways. This study was done to investigate the contribution of the INK4a-ARF locus in tumorigenesis of angiosarcoma of the liver. Alterations of p14(ARF), p16(INKa), and p53 in primary liver angiosarcoma from 19 patients were analyzed by methylation-specific polymerase chain reaction (MSP), restriction enzyme-related polymerase chain reaction (RE-PCR), microsatellite analysis, and DNA sequencing. As a control group, 12 angiosarcomas from other organs were analyzed. Promoter methylation of p14(ARF) was found in 5 of 19 cases (26%), and p16(INKa) showed aberrant promoter methylation in 12 of 19 cases (63%). One tumor (5%) had homozygous deletion of the INK4a-ARF locus. Methylation and deletion correlated with loss of mRNA transcription. Methylated p14(ARF) appeared in the context of a methylated p16(INKa) promoter in 3 cases of the 5 angiosarcomas methylated at p14(ARF). p14(ARF) aberrant methylation was not related to the presence of p53 mutations, which was detected in 6 of 19 (32%) cases. Alterations of the INK4a-ARF locus or p53 as were not established independent prognostic factors in these tumors. In conclusion, our data indicate that the INK4a-ARF locus is frequently inactivated in angiosarcoma of the liver and occurs independently of p53 mutations. PMID:12378512

  17. Enabling laser applications in microelectronics manufacturing

    Science.gov (United States)

    Delmdahl, Ralph; Brune, Jan; Fechner, Burkhard; Senczuk, Rolf

    2016-02-01

    In this experimental study, we report on high-pulse-energy excimer laser drilling into high-performance build-up films which are pivotal in microelectronics manufacturing. Build-up materials ABF-GX13 from Ajinomoto as well as ZS-100 from Zeon Corporation are evaluated with respect to their viability for economic excimer laser-based micro-via formation. Excimer laser mask imaging projection at laser wavelengths of 193, 248 and 308 nm is employed to generate matrices of smaller micro-vias with different diameters and via pitches. High drilling quality is achievable for all excimer laser wavelengths with the fastest ablation rates measured in the case of 248 and 308 nm wavelengths. The presence of glass fillers in build-up films as in the ABF-GX13 material poses some limitations to the minimum achievable via diameter. However, surprisingly good drilling results are obtainable as long as the filler dimensions are well below the diameter of the micro-vias. Sidewall angles of vias are controllable by adjusting the laser energy density and pulse number. In this work, the structuring capabilities of excimer lasers in build-up films as to taper angle variations, attainable via diameters, edge-stop behavior and ablation rates will be elucidated.

  18. GAS LASERS FOR STRONG-FIELD APPLICATIONS.

    Energy Technology Data Exchange (ETDEWEB)

    POGORELSKY,I.V.

    2004-09-15

    Atomic-, molecular- and excimer-gas lasers employ variety of pumping schemes including electric discharge, optical, or chemical reactions and cover a broad spectral range from UV to far-IR. Several types of gas lasers can produce multi-kilojoule pulses and kilowatts of average power. Among them, excimer- and high-pressure molecular lasers have sufficient bandwidth for generating pico- and femtosecond pulses. Projects are underway and prospects are opening up to bring ultrafast gas laser technology to the front lines of advanced accelerator applications.

  19. Autokeratomileusis Laser

    Science.gov (United States)

    Kern, Seymour P.

    1987-03-01

    Refractive defects such as myopia, hyperopia, and astigmatism may be corrected by laser milling of the cornea. An apparatus combining automatic refraction/keratometry and an excimer type laser for precision reshaping of corneal surfaces has been developed for testing. When electronically linked to a refractometer or keratometer or holographic imaging device, the laser is capable of rapidly milling or ablating corneal surfaces to preselected dioptric power shapes without the surgical errors characteristic of radial keratotomy, cryokeratomileusis or epikeratophakia. The excimer laser simultaneously generates a synthetic Bowman's like layer or corneal condensate which appears to support re-epithelialization of the corneal surface. An electronic feedback arrangement between the measuring instrument and the laser enables real time control of the ablative milling process for precise refractive changes in the low to very high dioptric ranges. One of numerous options is the use of a rotating aperture wheel with reflective portions providing rapid alternate ablation/measurement interfaced to both laser and measurement instrumentation. The need for the eye to be fixated is eliminated or minimized. In addition to reshaping corneal surfaces, the laser milling apparatus may also be used in the process of milling both synthetic and natural corneal inlays for lamellar transplants.

  20. Laser in ophthalmology

    International Nuclear Information System (INIS)

    The article presents a brief history of the use of laser in ophthalmology in Norway, from the introduction of the first argon-photocoalulator in 1972 to the excimer laser in 1990. The argon-photocoagulator is in daily us in all Eye Departments in Norway and the main group of patients treated are those with diabetic retionopathy. Glaucoma has been treated with argon-laser with good results for the last ten years. YAG-laser, introduced in Norway in 1985, is used to treat secondary cataracts which occur after extracapsular cataract extractions and implantation of artificial lenses. In 1990, the excimer laser was introduced for refractive surgery (myopia, astigmatism). 4 refs., 6 figs., 1 tab

  1. The DNA damage checkpoint precedes activation of ARF in response to escalating oncogenic stress during tumorigenesis

    DEFF Research Database (Denmark)

    Evangelou, K.; Bartkova, J.; Kotsinas, A.;

    2013-01-01

    Oncogenic stimuli trigger the DNA damage response (DDR) and induction of the alternative reading frame (ARF) tumor suppressor, both of which can activate the p53 pathway and provide intrinsic barriers to tumor progression. However, the respective timeframes and signal thresholds for ARF induction...

  2. Nuclear trafficking of EGFR by Vps34 represses Arf expression to promote lung tumor cell survival.

    Science.gov (United States)

    Dayde, D; Guerard, M; Perron, P; Hatat, A-S; Barrial, C; Eymin, B; Gazzeri, S

    2016-07-28

    Epidermal growth factor receptor (EGFR) is a cell surface receptor that has an essential role in cell proliferation and survival, and overexpression of EGFR is a common feature of human cancers. In Non-small-cell lung cancer (NSCLC), activating mutations of EGFR have also been described. We recently showed that mutant EGFR-L858R inhibits the expression of the p14ARF tumor-suppressor protein to promote cell survival. In this study, we defined the molecular bases by which EGFR controls Arf expression. Using various lung tumor models, we showed that EGF stimulation inhibits Arf transcription by a mechanism involving the nuclear transport and recruitment of EGFR to the Arf promoter. We unraveled the vesicular trafficking protein Vps34 as a mediator of EGFR nuclear trafficking and showed that its neutralization prevents the accumulation of EGFR to the Arf promoter in response to ligand activation. Finally, in lung tumor cells that carry mutant EGFR-L858R, we demonstrated that inhibition of Vps34 using small interfering RNA restrains nuclear EGFR location and restores Arf expression leading to apoptosis. These findings identify the Arf tumor suppressor as a new transcriptional target of nuclear EGFR and highlight Vps34 as an important regulator of the nuclear EGFR/Arf survival pathway. As a whole, they provide a mechanistic explanation to the inverse correlation between nuclear expression of EGFR and overall survival in NSCLC patients. PMID:26686095

  3. Membrane association of the Arabidopsis ARF exchange factor GNOM involves interaction of conserved domains

    DEFF Research Database (Denmark)

    Anders, Nadine; Nielsen, Michael M.; Keicher, Jutta;

    2008-01-01

    The GNOM protein plays a fundamental role in Arabidopsis thaliana development by regulating endosome-to-plasma membrane trafficking required for polar localization of the auxin efflux carrier PIN1. GNOM is a family member of large ARF guanine nucleotide exchange factors (ARF-GEFs), which regulate...

  4. A short acidic motif in ARF guards against mitochondrial dysfunction and melanoma susceptibility

    DEFF Research Database (Denmark)

    Christensen, Claus; Bartkova, Jirina; Mistrík, Martin; Hall, Arnaldur; Lange, Marina Krarup; Ralfkiær, Ulrik; Bartek, Jiri; Guldberg, Per

    2014-01-01

    ARF is a small, highly basic protein that can be induced by oncogenic stimuli and exerts growth-inhibitory and tumour-suppressive activities through the activation of p53. Here we show that, in human melanocytes, ARF is cytoplasmic, constitutively expressed, and required for maintaining low stead...

  5. Modeling of Kr-Xe discharge of excimer lamp

    Directory of Open Access Journals (Sweden)

    Belasri A.

    2013-03-01

    Full Text Available This paper reports the numerical simulation of Dielectric Barrier Discharge (DBD for Kr-Xe excilamp. The model of the discharge consists of three main modules: a plasma chemistry module, a circuit module and a Boltzmann equation module. The results predict the optimal operating conditions and describe the electrical and chemical properties of the KrXe* excimer lamp.

  6. HYPERMETHYLATION OF p14ARF PROMOTER REGION AND EXPRESION OF p14ARF GENE PRODUCT IN NON-SMALL CELL LUNG CANCER

    Institute of Scientific and Technical Information of China (English)

    TIAN Kai-hua; SHEN Yi; LUO Yi-rne; WANG Ming-zhao; LIU Hong-xu; ZHAO Hui-ru; ZHANG Lin

    2006-01-01

    Objective: This study was designed to investigate promoter methylation status and protein expression of p14ARF gene in non-small cell lung cancer, and value the role of p14ARF promoter methylation in carcinogenesis of non-small cell lung cancer. Methods: Promoter methylation status and protein expression of p14ARF gene in 40 cases of non-small cell lung cancer were analyzed by methylation specific polymerase china reaction (MSP), restriction enzyme-related polymerase chain reaction (RE-PCR) and immunohistochemistry (IHC). Results: The positive rates of p14ARF promoter methylation in tumor tissues and normal tissues adjacent to cancer were 17.5% (7/40) and 2.5% (1/40) respectively. There were statistically significant differences between them, P<0.05. The results of RE-PCR were consistent with that of MSP. The expression rate of p14ARF protein in tumor tissues was significantly lower than that in normal tissues adjacent to cancer, p<0.01. Promoter methylation status and protein expression of p14ARF gene in non-small cell lung cancer showed significantly an inverse correlation (r=-0.56, P<0.01), and both of them did not relate statistically with the clinicopathologic characteristics of patients such as histological classification, clinical stage, differentiation grade and lymph node involvement. Conclusion: Promoter methylation is a crucial mechanism of inactivation of p14ARF gene. Promoter methylation of p14ARF gene might be involved in carcinogenesis of non-small cell lung cancer, and is an early event in development process of non-small cell lung cancer. It might be used as a new target in gene treatments in the future.

  7. The Polycomb group proteins bind throughout the INK4A-ARF locus and are disassociated in senescent cells

    DEFF Research Database (Denmark)

    Bracken, Adrian P; Kleine-Kohlbrecher, Daniela; Dietrich, Nikolaj;

    2007-01-01

    The p16INK4A and p14ARF proteins, encoded by the INK4A-ARF locus, are key regulators of cellular senescence, yet the mechanisms triggering their up-regulation are not well understood. Here, we show that the ability of the oncogene BMI1 to repress the INK4A-ARF locus requires its direct associatio...

  8. Haze following Excimer Laser Photorefractive Keratectomy and Full-Refraction Prior to PRK%准分子激光角膜切削术后角膜上皮下混浊与术前总屈光度的关系

    Institute of Scientific and Technical Information of China (English)

    黄剑云; 孙斌; 张勇; 方华

    2000-01-01

    目的:探讨准分子激光角膜切削术(photorefractive keratectomy,PRK)后角膜上皮下混浊(Haze)与术前眼总 屈光度之间的关系。方法:将接受PRK手术患者近视和散光的总屈光度分成低度(-1.00~-3.00D)、中度(-3. 25~-8.00D)、高度(-8.25~-16.00D以上)三组,同时对高度组中的角膜水化与非角膜水化进行统计,比较术后 角膜Haze形成情况。结果:低度组和中、高度组比较发生角膜Haze的程度差异有显著性(P<0.01),而中度组和高 度组比较差异无显著性(P>0.05),术中角膜水化组与非水化组发生角膜Haze比较具有显著性差异(P<0.05)。 结论:PRK术后Haze形成与术前治疗总屈光度之间没有正相关系,术后科学有效地使用皮质类固醇激素和辅助用 药以及对高度近视眼治疗过程中进行角膜水化作用是减少Haze形成的有效方法。%Objective To explore the connection between the Haze after Excimer Laser photorefraction Keratectomy and Full- Refraction Before PRK. Methods 298 eases(579 eyes) undergoing PRK full-reffraction, including myopia and astigmatism, were divided into three groups: mild(-1.00~-3.00D), moderate (-3.25~-8.00 D),severe(-8.25~16.00D). The severe group(170 eyes) was subdivided into two groubs:76 eyes washed with Ringer's solution during operation (the treatment group); 94 eyes unwashed (the control group). All the data were statistically analyzed. The follow - up was 6~12 months (average 8 month). FResults The comparative analysis showed no significant differences between the three groups(P0.05). Conclusion There is no relationship between Haze after operation and full -refraction before operation. The scientific and effective use of corticosteriod and other drugs, and cornea watering as a supplementary treatment will reduce the formation of Haze.

  9. Plasma plume induced during pulsed laser deposition of hydroxyapatite

    International Nuclear Information System (INIS)

    Pulsed laser deposition is well-established method of deposition of thin films on different substrates. The particles ablated from a target owing to laser radiation-target interaction form a plasma plume and subsequently are deposited on a substrate. The mechanism of plasma formation and expansion consists of three stages. During the interaction of the laser beam with a material the target is heated to the temperatures exceeding the boiling temperatures and sometimes also the critical temperatures. The characteristic time of the target temperature rise is from 1 nanosecond in the case of dielectrics to some hundreds nanoseconds in the case of metals case of metals. In the same time the process of ablation begins. In the second stage the ablated particles are heated by the laser beam to the temperatures of 10-20 kK and form a plasma plume. The characteristic time of plasma heating is 10-100 nanoseconds. This process depends on the intensity of the laser beam and energy of quanta. Next the laser radiation decays (laser pulse duration FWHM ∼ 20-50 ns) and plasma plume expands adiabatically. In this work plasma plume induced by ArF excimer laser ablation of a hydroxyapatite (Ca10(PO4)6(OH)2) target during deposition process has been studied in different ambient conditions., i.e in air or water vapour with the addition of oxygen. Hydroxyapatite is a biocompatible ceramic. It may be deposited onto orthopedic implants in order to increase the bone-implant contact or over a porous titanium coating where it is used to promote bone ingrowth. The process of deposition significantly depends on mechanisms of plasma plume formation and its expansion. ArF laser operated at the wavelength of 193 nm with the pulse energy of 300 mJ and 20 ns pulse duration. The emission spectra of the plasma plume were registered with the use of a spectrograph and a fast gate, micro-channel plate (MCP) image intensifier optically coupled to an Andor CCD camera. The emission spectra consist mainly

  10. Comparison of aspheric keratectomy excimer laser subepithelial keratomileusis (LASEK)and aspheric laser in situ keratomileusis(LASIK) for different thickness corneal%非球面切削LASEK和LASIK治疗不同厚度角膜的高度近视

    Institute of Scientific and Technical Information of China (English)

    朱云喜; 金敏; 王小园; 高宗银; 杨为中; 朱远军

    2010-01-01

    目的 探讨角膜波前像差联合Q值优化的非球面切削准分子激光上皮下角膜切削术(LASEK)与角膜波前像差联合Q值优化的非球面切削准分子激光原位角膜磨镶术(LASIK),分别治疗角膜薄(500μm)的高度近视的临床疗效比较.方法 选取角膜厚度薄的高度近视患者行LASEK治疗25例(42只眼),角膜厚的高度近视患者38例(65只眼),比较术前视力、年龄、角膜厚度、切削厚度、剩余角膜厚度、等效球镜度、球差、慧差、总阶像差,术后2周,4周,3月,6月的视力,比较术后6月两组视力、等效球镜度、球差、慧差、总阶像差、HAZE等级.结果 两种手术方式术后6月内的视力,术后6月的等效球镜度、球差、慧差、总阶像差均无统计学意义,治疗高度近视具有相同均具有很高的安全性、有效性及可预测性且两组具有相同的临床疗效.结论 非球面切削的LASEK治疗角膜薄的高度近视与非球面切削的LASIK治疗角膜厚的高度近视具有相同的临床疗效.%Objective To compare the clinical curative effect of corneal wavefront-guided combining Q-value guided aspheric keratctomy excimer LASEK for high myopia of thin cornea (500μm). Methods Of selected 25 high myopia of thin cornea (42 eyes), and 38 high myopia of thick cornea (65 eyes), compared the preoperative uncorrected visual acuity (UCVA), age, corneal thickness, atherectomy thickness,remnant thickness, spherical equivalent (SE), Coma-like RMS (root of mean square), spherical-like RMS,RMSg (root of mean square of general aberration) with postoperative UCVA of 2, 4 weeks, 1 month, 3, 6 months SE, Coma-like RMS, spherical-like RMS, RMSg, Level of Haze. Results There were no statistically significant differences between two groups 6 months aiter operation in UCVA, spherical equivalent (SE),Coma-like RIMS, spherical-like RMS and RMSg. Both groups showed high safety, efficacy, predictability and the same clinical curative effect

  11. Genome-wide identification, isolation and expression analysis of auxin response factor (ARF) gene family in sweet orange (Citrus sinensis)

    OpenAIRE

    Li, Si-Bei; OuYang, Wei-Zhi; Hou, Xiao-Jin; Xie, Liang-Liang; Hu, Chun-Gen; Zhang, Jin-Zhi

    2015-01-01

    Auxin response factors (ARFs) are an important family of proteins in auxin-mediated response, with key roles in various physiological and biochemical processes. To date, a genome-wide overview of the ARF gene family in citrus was not available. A systematic analysis of this gene family in citrus was begun by carrying out a genome-wide search for the homologs of ARFs. A total of 19 nonredundant ARF genes (CiARF) were found and validated from the sweet orange. A comprehensive overview of the Ci...

  12. Preliminary characterisation of new glass reference materials (GSA-1G, GSC-1G, GSD-1G and GSE-1G) by laser ablation-inductively coupled plasma-mass spectrometry using 193 nm, 213 nm and 266 nm wavelengths

    Science.gov (United States)

    Guillong, M.; Hametner, K.; Reusser, E.; Wilson, S.A.; Gunther, D.

    2005-01-01

    New glass reference materials GSA-1G, GSC-1G, GSD-1G and GSE-1G have been characterised using a prototype solid state laser ablation system capable of producing wavelengths of 193 nm, 213 nm and 266 nm. This system allowed comparison of the effects of different laser wavelengths under nearly identical ablation and ICP operating conditions. The wavelengths 213 nm and 266 nm were also used at higher energy densities to evaluate the influence of energy density on quantitative analysis. In addition, the glass reference materials were analysed using commercially available 266 nm Nd:YAG and 193 nm ArF excimer lasers. Laser ablation analysis was carried out using both single spot and scanning mode ablation. Using laser ablation ICP-MS, concentrations of fifty-eight elements were determined with external calibration to the NIST SRM 610 glass reference material. Instead of applying the more common internal standardisation procedure, the total concentration of all element oxide concentrations was normalised to 100%. Major element concentrations were compared with those determined by electron microprobe. In addition to NIST SRM 610 for external calibration, USGS BCR-2G was used as a more closely matrix-matched reference material in order to compare the effect of matrix-matched and non matrix-matched calibration on quantitative analysis. The results show that the various laser wavelengths and energy densities applied produced similar results, with the exception of scanning mode ablation at 266 nm without matrix-matched calibration where deviations up to 60% from the average were found. However, results acquired using a scanning mode with a matrix-matched calibration agreed with results obtained by spot analysis. The increased abundance of large particles produced when using a scanning ablation mode with NIST SRM 610, is responsible for elemental fractionation effects caused by incomplete vaporisation of large particles in the ICP.

  13. Variable laser attenuator

    Science.gov (United States)

    Foltyn, Stephen R.

    1988-01-01

    The disclosure relates to low loss, high power variable attenuators comprng one or more transmissive and/or reflective multilayer dielectric filters. The attenuator is particularly suitable to use with unpolarized lasers such as excimer lasers. Beam attenuation is a function of beam polarization and the angle of incidence between the beam and the filter and is controlled by adjusting the angle of incidence the beam makes to the filter or filters. Filters are selected in accordance with beam wavelength.

  14. Proteobacterial ArfA peptides are synthesized from non-stop messenger RNAs.

    Science.gov (United States)

    Schaub, Ryan E; Poole, Stephen J; Garza-Sánchez, Fernando; Benbow, Sarah; Hayes, Christopher S

    2012-08-24

    The translation of non-stop mRNA (which lack in-frame stop codons) represents a significant quality control problem for all organisms. In eubacteria, the transfer-messenger RNA (tmRNA) system facilitates recycling of stalled ribosomes from non-stop mRNA in a process termed trans-translation or ribosome rescue. During rescue, the nascent chain is tagged with the tmRNA-encoded ssrA peptide, which promotes polypeptide degradation after release from the stalled ribosome. Escherichia coli possesses an additional ribosome rescue pathway mediated by the ArfA peptide. The E. coli arfA message contains a hairpin structure that is cleaved by RNase III to produce a non-stop transcript. Therefore, ArfA levels are controlled by tmRNA through ssrA-peptide tagging and proteolysis. Here, we examine whether ArfA homologues from other bacteria are also regulated by RNase III and tmRNA. We searched 431 arfA coding sequences for mRNA secondary structures and found that 82.8% of the transcripts contain predicted hairpins in their 3'-coding regions. The arfA hairpins from Haemophilus influenzae, Proteus mirabilis, Vibrio fischeri, and Pasteurella multocida are all cleaved by RNase III as predicted, whereas the hairpin from Neisseria gonorrhoeae functions as an intrinsic transcription terminator to generate non-stop mRNA. Each ArfA homologue is ssrA-tagged and degraded when expressed in wild-type E. coli cells, but accumulates in mutants lacking tmRNA. Together, these findings show that ArfA synthesis from non-stop mRNA is a conserved mechanism to regulate the alternative ribosome rescue pathway. This strategy ensures that ArfA homologues are only deployed when the tmRNA system is incapacitated or overwhelmed by stalled ribosomes. PMID:22791716

  15. p14ARF upregulation of p53 and enhanced effects of 5-fluorouracil in pancreatic cancer

    Institute of Scientific and Technical Information of China (English)

    张群华; 倪泉兴; 甘军; 沈兆忠; 罗建民; 金忱; 张妞; 张延龄

    2003-01-01

    Objective To investigate the synergistic antitumor effects of combined use of p14ARF gene and 5-fluorouracil (5-Fu) in pancreatic cancer.Methods A human pancreatic cancer cell line PC-3 was transfected with lipofectin-mediated recombinant p14ARF gene, and was then administered with 5-Fu. Cell growth, morphological changes, cell cycle, apoptosis, and molecular changes were measured using the MTT assay, flow cytometry, RT-PCR, Western blotting, and immunocytochemical assays.Results After transfection of p14ARF, cell growth was obviously inhibited, resulting in an accumulation of cells in the G1 phase. The proportion of cells in the G1 phase was significantly increased from 58.51% to 75.92 %, and in the S and G2/M phases decreased significantly from 20.05% to 12.60%, and from 21.44% to 11.48 %, respectively, as compared with those of the control groups. PC-3/p14ARF cells that underwent 5-Fu treatment had significantly greater G2/M phase accumulation, from 11.48% to 53.47 %. The apoptopic index was increased in PC-3/p14ARF cells from 3.64% to 19.62%. The MTT assay showed p14ARF-expressing cells were significantly more sensitive to 5-Fu (0.01-10 mg/L) than those devoid of p14ARF expression (P<0.01). Western blotting showed p14ARF upregulates p53 expression. Conclusion Combined use of p14ARF gene and 5-Fu acts synergistically to inhibit pancreatic cancer cell proliferation, suggesting a new anticancer strategy.

  16. Interaction of serologically defined colon cancer antigen-3 with Arf6 and its predominant expression in the mouse testis.

    Science.gov (United States)

    Sakagami, Hiroyuki; Hara, Yoshinobu; Fukaya, Masahiro

    2016-09-01

    ADP ribosylation factor 6 (Arf6) is a small GTPase that regulates endosomal trafficking and actin cytoskeleton remodeling. Here, we identified the serologically defined colon antigen-3 (SDCCAG3) as an Arf6-interacting protein by yeast two-hybrid screening with a constitutively active Arf6 mutant. SDCCAG3 interacts specifically with Arf6 among the Arf family members through its 101  C-terminal amino acids. SDCCAG3 is expressed most intensely in the testis at the mRNA and protein levels. In the testis, SDCCAG3 is expressed in spermatocytes and spermatids. We also show that full-length SDCCAG3, but not a mutant lacking the ability to interact with Arf6, is recruited to the midbody during cytokinesis when expressed exogenously in HeLa cells. These findings suggest that SDCCAG3 might function in endosomal trafficking downstream of Arf6. PMID:27373827

  17. India and the ARF: the post-Pokhran II phase

    International Nuclear Information System (INIS)

    India and Southeast Asia have re-emerged on the global and regional scene in a way that cannot be ignored. India began to mark its presence felt with its Look East Policy and its policy of liberalisation. The Association of Southeast Asian Nations (ASEAN) too began acknowledging India's new status and was accommodated as a dialogue partner in the charmed circle of miracle economics. The magic of the miracle began to wear off as the currency crisis began to strike each of the economies one by one. Even before these states could recover from the shock of the economic crisis, New Delhi tested its bombs in Pokhran. Quite imperceptibly, the dynamics of security and economics had begun to unfold. What impact these developments have had on India's links with the ASEAN Regional Forum (ARF) and its participation in it is discussed

  18. Increased gene dosage of Ink4a/Arf results in cancer resistance and normal aging

    OpenAIRE

    Matheu, Ander; Pantoja, Cristina; Efeyan, Alejo; Criado, Luis M.; Martín-Caballero, Juan; Flores, Juana M.; Klatt, Peter; Serrano, Manuel

    2004-01-01

    Mammalian genes frequently present allelic variants that differ in their expression levels and that, in the case of tumor suppressor genes, can be of relevance for cancer susceptibility and aging. We report here the characterization of a novel mouse model with increased activity for the Ink4a and Arf tumor suppressors. We have generated a “super Ink4a/Arf” mouse strain carrying a transgenic copy of the entire Ink4a/Arf locus. Cells derived from super Ink4a/Arf mice have increased resistance t...

  19. 2D elemental mapping of sections of human kidney stones using laser ablation inductively-coupled plasma-mass spectrometry: Possibilities and limitations

    Science.gov (United States)

    Vašinová Galiová, Michaela; Čopjaková, Renata; Škoda, Radek; Štěpánková, Kateřina; Vaňková, Michaela; Kuta, Jan; Prokeš, Lubomír; Kynický, Jindřich; Kanický, Viktor

    2014-10-01

    A 213 nm Nd:YAG-based laser ablation (LA) system coupled to quadrupole-based inductively coupled plasma-mass spectrometer and an ArF* excimer-based LA-system coupled to a double-focusing sector field inductively coupled plasma-mass spectrometer were employed to study the spatial distribution of various elements in kidney stones (uroliths). Sections of the surfaces of uroliths were ablated according to line patterns to investigate the elemental profiles for the different urolith growth zones. This exploratory study was mainly focused on the distinguishing of the main constituents of urinary calculus fragments by means of LA-ICP-mass spectrometry. Changes in the ablation rate for oxalate and phosphate phases related to matrix density and hardness are discussed. Elemental association was investigated on the basis of 2D mapping. The possibility of using NIST SRM 1486 Bone Meal as an external standard for calibration was tested. It is shown that LA-ICP-MS is helpful for determination of the mineralogical composition and size of all phases within the analyzed surface area, for tracing down elemental associations and for documenting the elemental content of urinary stones. LA-ICP-MS results (elemental contents and maps) are compared to those obtained with electron microprobe analysis and solution analysis ICP-MS.

  20. Excimer emission from pulsed microhollow cathode discharges in xenon

    International Nuclear Information System (INIS)

    Direct current (dc) microhollow cathode discharge (MHCD) is an intense source for excimer radiation in vacuum ultraviolet at a wavelength of 172 nm in a high pressure xenon (Xe) gas. The concentration of precursors for the excimer formation, i.e., excited and ionized gas atoms, increases significantly by applying high voltage pulse onto the dc MHCD over the pulse duration range from 20 to 100 ns. The intensity of the excimer emission for the voltage pulse of 20 ns duration exceeds that of the emission intensity obtained from the same MHCD operated only in the dc mode, by one order of magnitude. In addition, the emission intensity increases by one order of magnitude over the pulse duration range from 20 to 100 ns. It can be assumed that the emission intensity of the MHCD source increases as long as the duration of the high voltage pulse is shorter than the electron relaxation time. For the high voltage pulse of 100 ns duration, the emission intensity has been found to be further enhanced by a factor of three when the gas pressure is increased from 200 to 800 mbar

  1. ARF6, PI3-kinase and host cell actin cytoskeleton in Toxoplasma gondii cell invasion

    International Nuclear Information System (INIS)

    Toxoplasma gondii infects a variety of different cell types in a range of different hosts. Host cell invasion by T. gondii occurs by active penetration of the host cell, a process previously described as independent of host actin polymerization. Also, the parasitophorous vacuole has been shown to resist fusion with endocytic and exocytic pathways of the host cell. ADP-ribosylation factor-6 (ARF6) belongs to the ARF family of small GTP-binding proteins. ARF6 regulates membrane trafficking and actin cytoskeleton rearrangements at the plasma membrane. Here, we have observed that ARF6 is recruited to the parasitophorous vacuole of tachyzoites of T. gondii RH strain and it also plays an important role in the parasite cell invasion with activation of PI3-kinase and recruitment of PIP2 and PIP3 to the parasitophorous vacuole of invading parasites. Moreover, it was verified that maintenance of host cell actin cytoskeleton integrity is important to parasite invasion.

  2. Aspergillus nidulans ArfB Plays a Role in Endocytosis and Polarized Growth ▿ †

    OpenAIRE

    Lee, Soo Chan; Schmidtke, Sabrina N.; Dangott, Lawrence J.; Shaw, Brian D.

    2008-01-01

    Filamentous fungi undergo polarized growth throughout most of their life cycles. The Spitzenkörper is an apical organelle composed primarily of vesicles that is unique to filamentous fungi and is likely to act as a vesicle supply center for tip growth. Vesicle assembly and trafficking are therefore important for hyphal growth. ADP ribosylation factors (Arfs), a group of small GTPase proteins, play an important role in nucleating vesicle assembly. Little is known about the role of Arfs in fila...

  3. ARF Is Required for Maintenance of Yeast Golgi and Endosome Structure and Function

    OpenAIRE

    Gaynor, Erin C.; Chen, Chih-Ying; Emr, Scott D.; Graham, Todd R.

    1998-01-01

    ADP ribosylation factor (ARF) is thought to play a critical role in recruiting coatomer (COPI) to Golgi membranes to drive transport vesicle budding. Yeast strains harboring mutant COPI proteins exhibit defects in retrograde Golgi to endoplasmic reticulum protein transport and striking cargo-selective defects in anterograde endoplasmic reticulum to Golgi protein transport. To determine whether arf mutants exhibit similar phenotypes, the anterograde transport kinetics of multiple cargo protein...

  4. NtGNL1a ARF-GEF acts in endocytosis in tobacco cells

    OpenAIRE

    Jelínková, A. (Adriana); Müller, K.; Pařezová, M. (Markéta); Petrášek, J. (Jan)

    2015-01-01

    Background Processes of anterograde and retrograde membrane trafficking play an important role in cellular homeostasis and dynamic rearrangements of the plasma membrane (PM) in all eukaryotes. These processes depend on the activity of adenosine ribosylation factors (ARFs), a family of GTP-binding proteins and their guanine exchange factors (GEFs). However, knowledge on the function and specificity of individual ARF-GEFs for individual steps of membrane trafficking pathways is still limited in...

  5. Genome-wide identification and expression profiling of auxin response factor (ARF) gene family in maize

    OpenAIRE

    Xing, Hongyan; Pudake, Ramesh N.; Guo, Ganggang; Xing, Guofang; Hu, Zhaorong; Zhang, Yirong; Sun, Qixin; Ni, Zhongfu

    2011-01-01

    Background Auxin signaling is vital for plant growth and development, and plays important role in apical dominance, tropic response, lateral root formation, vascular differentiation, embryo patterning and shoot elongation. Auxin Response Factors (ARFs) are the transcription factors that regulate the expression of auxin responsive genes. The ARF genes are represented by a large multigene family in plants. The first draft of full maize genome assembly has recently been released, however, to our...

  6. P53- and mevalonate pathway-driven malignancies require Arf6 for metastasis and drug resistance.

    Science.gov (United States)

    Hashimoto, Ari; Oikawa, Tsukasa; Hashimoto, Shigeru; Sugino, Hirokazu; Yoshikawa, Ayumu; Otsuka, Yutaro; Handa, Haruka; Onodera, Yasuhito; Nam, Jin-Min; Oneyama, Chitose; Okada, Masato; Fukuda, Mitsunori; Sabe, Hisataka

    2016-04-11

    Drug resistance, metastasis, and a mesenchymal transcriptional program are central features of aggressive breast tumors. The GTPase Arf6, often overexpressed in tumors, is critical to promote epithelial-mesenchymal transition and invasiveness. The metabolic mevalonate pathway (MVP) is associated with tumor invasiveness and known to prenylate proteins, but which prenylated proteins are critical for MVP-driven cancers is unknown. We show here that MVP requires the Arf6-dependent mesenchymal program. The MVP enzyme geranylgeranyl transferase II (GGT-II) and its substrate Rab11b are critical for Arf6 trafficking to the plasma membrane, where it is activated by receptor tyrosine kinases. Consistently, mutant p53, which is known to support tumorigenesis via MVP, promotes Arf6 activation via GGT-II and Rab11b. Inhibition of MVP and GGT-II blocked invasion and metastasis and reduced cancer cell resistance against chemotherapy agents, but only in cells overexpressing Arf6 and components of the mesenchymal program. Overexpression of Arf6 and mesenchymal proteins as well as enhanced MVP activity correlated with poor patient survival. These results provide insights into the molecular basis of MVP-driven malignancy. PMID:27044891

  7. ELMOD2 is an Arl2 GTPase-activating protein that also acts on Arfs.

    Science.gov (United States)

    Bowzard, J Bradford; Cheng, Dongmei; Peng, Junmin; Kahn, Richard A

    2007-06-15

    Regulatory GTPases in the Ras superfamily employ a cycle of alternating GTP binding and hydrolysis, controlled by guanine nucleotide exchange factors and GTPase-activating proteins (GAPs), as essential features of their actions in cells. Studies of these GAPs and guanine nucleotide exchange factors have provided important insights into our understanding of GTPase signaling and biology. Within the Ras superfamily, the Arf family is composed of 30 members in mammals, including 22 Arf-like (Arl) proteins. Much less is known about the mechanisms of cell regulation by Arls than by Arfs. We report the purification from bovine testis of an Arl2 GAP and its identity as ELMOD2, a protein with no previously described function. ELMOD2 is one of six human proteins that contain an ELMO domain, and a second member, ELMOD1, was also found to have Arl2 GAP activity. Surprisingly, ELMOD2 also exhibited GAP activity against Arf proteins even though it does not contain the canonical Arf GAP sequence signature. The broader specificity of ELMOD2, as well as the previously described role for ELMO1 and ELMO2 in linking Arf6 and Rac1 signaling, suggests that ELMO family members may play a more general role in integrating signaling pathways controlled by Arls and other GTPases. PMID:17452337

  8. Constitutive auxin response in Physcomitrella reveals complex interactions between Aux/IAA and ARF proteins.

    Science.gov (United States)

    Lavy, Meirav; Prigge, Michael J; Tao, Sibo; Shain, Stephanie; Kuo, April; Kirchsteiger, Kerstin; Estelle, Mark

    2016-01-01

    The coordinated action of the auxin-sensitive Aux/IAA transcriptional repressors and ARF transcription factors produces complex gene-regulatory networks in plants. Despite their importance, our knowledge of these two protein families is largely based on analysis of stabilized forms of the Aux/IAAs, and studies of a subgroup of ARFs that function as transcriptional activators. To understand how auxin regulates gene expression we generated a Physcomitrella patens line that completely lacks Aux/IAAs. Loss of the repressors causes massive changes in transcription with misregulation of over a third of the annotated genes. Further, we find that the aux/iaa mutant is blind to auxin indicating that auxin regulation of transcription occurs exclusively through Aux/IAA function. We used the aux/iaa mutant as a simplified platform for studies of ARF function and demonstrate that repressing ARFs regulate auxin-induced genes and fine-tune their expression. Further the repressing ARFs coordinate gene induction jointly with activating ARFs and the Aux/IAAs. PMID:27247276

  9. INK4/ARF transcript expression is associated with chromosome 9p21 variants linked to atherosclerosis.

    Directory of Open Access Journals (Sweden)

    Yan Liu

    Full Text Available Genome-wide association studies (GWAS have linked common single nucleotide polymorphisms (SNPs on chromosome 9p21 near the INK4/ARF (CDKN2A/B tumor suppressor locus with risk of atherosclerotic diseases and type 2 diabetes mellitus. To explore the mechanism of this association, we investigated whether expression of proximate transcripts (p16(INK4a, p15(INK4b, ARF, ANRIL and MTAP correlate with genotype of representative 9p21 SNPs.We analyzed expression of 9p21 transcripts in purified peripheral blood T-cells (PBTL from 170 healthy donors. Samples were genotyped for six selected disease-related SNPs spanning the INK4/ARF locus. Correlations among these variables were determined by univariate and multivariate analysis. Significantly reduced expression of all INK4/ARF transcripts (p15(INK4b, p16(INK4a, ARF and ANRIL was found in PBTL of individuals harboring a common SNP (rs10757278 associated with increased risk of coronary artery disease, stroke and aortic aneurysm. Expression of MTAP was not influenced by rs10757278 genotype. No association of any these transcripts was noted with five other tested 9p21 SNPs.Genotypes of rs10757278 linked to increased risk of atherosclerotic diseases are also associated with decreased expression in PBTL of the INK4/ARF locus, which encodes three related anti-proliferative transcripts of known importance in tumor suppression and aging.

  10. Constitutive auxin response in Physcomitrella reveals complex interactions between Aux/IAA and ARF proteins

    Science.gov (United States)

    Lavy, Meirav; Prigge, Michael J; Tao, Sibo; Shain, Stephanie; Kuo, April; Kirchsteiger, Kerstin; Estelle, Mark

    2016-01-01

    The coordinated action of the auxin-sensitive Aux/IAA transcriptional repressors and ARF transcription factors produces complex gene-regulatory networks in plants. Despite their importance, our knowledge of these two protein families is largely based on analysis of stabilized forms of the Aux/IAAs, and studies of a subgroup of ARFs that function as transcriptional activators. To understand how auxin regulates gene expression we generated a Physcomitrella patens line that completely lacks Aux/IAAs. Loss of the repressors causes massive changes in transcription with misregulation of over a third of the annotated genes. Further, we find that the aux/iaa mutant is blind to auxin indicating that auxin regulation of transcription occurs exclusively through Aux/IAA function. We used the aux/iaa mutant as a simplified platform for studies of ARF function and demonstrate that repressing ARFs regulate auxin-induced genes and fine-tune their expression. Further the repressing ARFs coordinate gene induction jointly with activating ARFs and the Aux/IAAs. DOI: http://dx.doi.org/10.7554/eLife.13325.001 PMID:27247276

  11. Effect of cell cycle inhibitor p19ARF on senescence of human diploid cell

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    To investigate the effect of cell cycle inhibitor p19ARF on replicative senescence of human diploid cell, recombinant p19ARF eukaryotic expression vector was constructed and p19ARF gene was transfected into human diploid fibroblasts (WI-38 cells) by liposome-mediated transfection for overexpression. Then, the effects of p19ARF on replicative senescence of WI-38 cells were observed. The results re- vealed that, compared with control cells, the WI-38 cells in which p19ARF gene was introduced showed significant up-regulation of p53 and p21 expression level, decrease of cell generation by 10 12 generations, decline of cell growth rate with cell cycle being arrested at G1 phase, increase of positive rate of senescent marker SA-β-gal staining, and decrease of mitochondrial membrane potential. The morphology of the transfected fibroblasts presented the characteristics changes similar to senescent cells. These results indicated that high expression of p19ARF may promote the senescent process of human diploid cells.

  12. Ultrathin Al-doped transparent conducting zinc oxide films fabricated by pulsed laser deposition

    International Nuclear Information System (INIS)

    Al-doped transparent conducting zinc oxide (AZO) films, approximately 20-110 nm-thick, were deposited on glass substrates at substrate temperatures between 200 and 300 deg. C by pulsed laser deposition (PLD) using an ArF excimer laser (λ = 193 nm). When fabricated at a substrate temperature of 260 deg. C , a 40-nm-thick AZO film showed a low resistivity of 2.61 x 10-4 Ω.cm, carrier concentration of 8.64 x 1020 cm-3, and Hall mobility of 27.7 cm2/V.s. Furthermore, for an ultrathin 20-nm-thick film, a resistivity of 3.91 x 10-4 Ω.cm, carrier concentration of 7.14 x 1020 cm-3, and Hall mobility of 22.4 cm2/V.s were obtained. X-ray diffraction (XRD) spectra, obtained by the θ-2θ method, of the AZO films grown at a substrate temperature of 260 deg. C showed that the diffraction peak of the ZnO (0002) plane increased as the film thickness increased from 20 to 110 nm. The full-width-at-half-maximum (FWHM) values were 0.5500 deg., 0.3845 deg., and 0.2979 deg. for film thicknesses of 20, 40, and 110 nm, respectively. For these films, the values of the average transmittance in visible light wavelengths (400-700 nm) were 95.1%, 94.2%, and 96.6%, respectively. Field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM) observations showed that even the 20-nm-thick films did not show island structures. In addition, exfoliated areas or vacant and void spaces were not observed for any of the films

  13. Effects of overexpressing p14ARF on the apoptosis in human melanoma cells irradiated with γ-ray

    Institute of Scientific and Technical Information of China (English)

    PENG Lixia; ZHANG Wei; LIU Huitu; HE Dacheng; GAO Ping

    2003-01-01

    Tumor suppressor ARF can induce cell cycle arrest or apoptosis by activating p53. In order to explore the molecular mechanism of the induction of apoptosis by p14ARF, a human melanoma cell model overexpressing p14ARF was constructed. Present study indicated that in the cells overexpressing p14ARF, p53 was accumulated in nucleus while it dispersed in cytosol in the control cells. Irradiated with γ-ray, overexpressing p14ARF promoted the apoptosis of A375 cells, triggered Smac release from mitochondria to cytosol, and increased the expression of p53, Bax, Caspase-3, Caspase-9, p21cip1 and p27kip1. However, the protein level of Bcl-2 and phospho-ERK was down-regulated. These results suggested a possible mechanism of p14ARF in promotion of apoptosis.

  14. Ablation of polymers by ultraviolet pulsed laser

    International Nuclear Information System (INIS)

    The surface modifications of different polymers treated by far UV-Excimer laser (λ = 193mn, 248, 308nm) are analysed by X-Ray Photoelectrons Spectroscopy. The main feature observed depends strongly on the absorption coefficients. For the high absorbing polymers such (PVC, PS, PI,...) the mechanism of the UV-Excimer Laser interaction appears to be governed by an ablative photodecomposition process (APD) with an APD threshold. In the other limit, i.e. low absorbing polymer the interaction leads to a photothermal process. (author). 51 refs, 24 figs, 7 tabs

  15. A study of the composition of the products of laser-induced breakdown of hexogen, octogen, pentrite and trinitrotoluene using selected ion flow tube mass spectrometry and UV-Vis spectrometry.

    Science.gov (United States)

    Sovová, Kristýna; Dryahina, Kseniya; Spanel, Patrik; Kyncl, Martin; Civis, Svatopluk

    2010-05-01

    Four types of explosives were studied using a combination of Laser Induced Breakdown Spectroscopy (LIBS) and Selected Ion Flow Tube Mass Spectrometry (SIFT-MS). The LIBS technique uses short laser pulses (ArF excimer laser) as the energy source to convert small amounts samples into plasma and to produce the emission from their molecular fragments or atoms. SIFT-MS is a novel method for absolute quantification based on chemical ionization using three precursor ions, with the capability to determine concentrations of trace gases and vapours of volatile organic compounds in real time. This is the first time that SIFT-MS has been used to study the release of NO, NO(2), HCN, HNO(3), HONO, HCHO and C(2)H(2) after a laser-induced breakdown of pure explosive compounds HMX (1,3,5,7-tetranitro-1,3,5,7-tetraazacyclo-octane), RDX (1,3,5-trinitro-2-oxo-1,3,5-triazacyclo-hexane), PETN (pentaerithrityl-tetranitrate) and TNT (2,4,6-trinitrotoluene) in solid form. The radiation emitted after excitation was analysed using a time resolving UV-Vis spectrometer with a ICCD detector. Electronic bands of the CN radical (388 nm), the Swan system of the C(2) radical (512 nm), the NH radical (336 nm), the OH radical (308.4 nm) and atomic lines of oxygen, nitrogen and hydrogen were identified. Vibrational and excitation temperatures were determined from the intensity distributions and a scheme of chemical reactions responsible for the formation of the observed species was proposed. PMID:20419263

  16. Atomic force microscopy analysis of human cornea surface after UV (λ=266 nm) laser irradiation

    Science.gov (United States)

    Spyratou, E.; Makropoulou, M.; Moutsouris, K.; Bacharis, C.; Serafetinides, A. A.

    2009-07-01

    Efficient cornea reshaping by laser irradiation for correcting refractive errors is still a major issue of interest and study. Although the excimer laser wavelength of 193 nm is generally recognized as successful in ablating corneal tissue for myopia correction, complications in excimer refractive surgery leads to alternative laser sources and methods for efficient cornea treatment. In this work, ablation experiments of human donor cornea flaps were conducted with the 4th harmonic of an Nd:YAG laser, with different laser pulses. AFM analysis was performed for examination of the ablated cornea flap morphology and surface roughness.

  17. Development of convenient nitrogen laser by using control of discharge

    Science.gov (United States)

    Nakazawa, Seiichi; Yamaguchi, Eiichiro; Ishii, Yoshio

    2012-01-01

    Among the most important UV lasers are the excimer and the nitrogen. A nitrogen gas laser is widely used in various fields. We considered some ideas for a nitrogen laser built in more easily by using of triboluminescence. In this study, we discussed development and discussion of convenient nitrogen laser. We considered utilization of triboluminescence for control of discharge and the system of electric generator using triboluminescence in the longitudinally excited nitrogen laser.

  18. Laser in operative dentistry

    Directory of Open Access Journals (Sweden)

    E. Yasini

    1994-06-01

    Full Text Available Today laser has a lot of usage in medicine and dentistry. In the field of dentistry, laser is used in soft tissue surgery, sterilization of canals (in root canal therapy and in restorative dentistry laser is used for cavity preparation, caries removal, sealing the grooves (in preventive dentistry, etching enamel and dentin, composite polymerization and removal of tooth sensitivity. The use of Co2 lasers and Nd: YAG for cavity preparation, due to creating high heat causes darkness and cracks around the region of laser radiation. Also due to high temperature of these lasers, pulp damage is inevitable. So today, by using the Excimer laser especially the argon floride type with a wavelength of 193 nm, the problem of heat stress have been solved, but the use of lasers in dentistry, especially for cavity preparation needs more researches and evaluations.

  19. Losses of both products of the Cdkn2a/Arf locus contribute to asbestos-induced mesothelioma development and cooperate to accelerate tumorigenesis.

    Directory of Open Access Journals (Sweden)

    Deborah A Altomare

    Full Text Available The CDKN2A/ARF locus encompasses overlapping tumor suppressor genes p16(INK4A and p14(ARF, which are frequently co-deleted in human malignant mesothelioma (MM. The importance of p16(INK4A loss in human cancer is well established, but the relative significance of p14(ARF loss has been debated. The tumor predisposition of mice singly deficient for either Ink4a or Arf, due to targeting of exons 1α or 1β, respectively, supports the idea that both play significant and nonredundant roles in suppressing spontaneous tumors. To further test this notion, we exposed Ink4a(+/- and Arf(+/- mice to asbestos, the major cause of MM. Asbestos-treated Ink4a(+/- and Arf(+/- mice showed increased incidence and shorter latency of MM relative to wild-type littermates. MMs from Ink4a(+/- mice exhibited biallelic inactivation of Ink4a, loss of Arf or p53 expression and frequent loss of p15(Ink4b. In contrast, MMs from Arf(+/- mice exhibited loss of Arf expression, but did not require loss of Ink4a or Ink4b. Mice doubly deficient for Ink4a and Arf, due to deletion of Cdkn2a/Arf exon 2, showed accelerated asbestos-induced MM formation relative to mice deficient for Ink4a or Arf alone, and MMs exhibited biallelic loss of both tumor suppressor genes. The tumor suppressor function of Arf in MM was p53-independent, since MMs with loss of Arf retained functional p53. Collectively, these in vivo data indicate that both CDKN2A/ARF gene products suppress asbestos carcinogenicity. Furthermore, while inactivation of Arf appears to be crucial for MM pathogenesis, the inactivation of both p16(Ink4a and p19(Arf cooperate to accelerate asbestos-induced tumorigenesis.

  20. APPLICATIONS OF LASERS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Laser system based on a commercial microwave oscillator with time compression of a microwave pump pulse

    Science.gov (United States)

    Arteev, M. S.; Vaulin, V. A.; Slinko, V. N.; Chumerin, P. Yu; Yushkov, Yu G.

    1992-06-01

    An analysis is made of the possibility of using a commercial microsecond microwave oscillator, supplemented by a device for time compression of microwave pulses, in pumping of industrial lasers with a high efficiency of conversion of the pump source energy into laser radiation. The results are reported of preliminary experiments on the commissioning of an excimer XeCl laser.

  1. In vitro analysis of laser meniscectomy.

    Science.gov (United States)

    Vangsness, C T; Akl, Y; Nelson, S J; Liaw, L H; Smith, C F; Marshall, G J

    1995-01-01

    Partial meniscectomies were performed on 32 fresh human meniscal autopsy specimens. The following laser systems were tested: carbon dioxide (CO2), neodymium:yttrium aluminum garnet (Nd:YAG), potassium titanyl phosphate (KTP), holmium:YAG (Ho:YAG), and excimer. Meniscectomies with these lasers were compared with scalpel, mechanical, and electrocautery meniscectomies. Lasers were applied to specimens in and out of normal saline. Routine hematoxylin and eosin and sirius red sections were prepared for each specimen, and the depths of thermal changes were analyzed. Scanning electron microscopy was used to visualize the meniscectomy interface. Among these specimens, the scalpel and mechanical meniscectomies showed the least extension of cellular changes (range, 10-15 nm). The excimer laser caused the least tissue changes of the lasers tested. Tissue changes were less extensive with the pulsed CO2 laser than with the holmium:YAG, neodymium:YAG, and KTP lasers. Scanning electron microscopy showed that use of the scalpel meniscectomy resulted in the smoothest meniscectomy edge, followed by use of the excimer, CO2, holmium:YAG, neodymium:YAG, and KTP lasers. The most surface disruption occurred with electrocautery. Meniscectomies under saline required more energy and took longer in each case, with the holmium:YAG, neodymium:YAG, and CO2 laser cutting the best. Saline meniscectomies showed less thermal change. The CO2 and KTP lasers cut best in air. PMID:7641441

  2. ARF and ATM/ATR cooperate in p53-mediated apoptosis upon oncogenic stress

    International Nuclear Information System (INIS)

    Induction of apoptosis is pivotal for eliminating cells with damaged DNA or deregulated proliferation. We show that tumor suppressor ARF and ATM/ATR kinase pathways cooperate in the induction of apoptosis in response to elevated expression of c-myc, β-catenin or human papilloma virus E7 oncogenes. Overexpression of oncogenes leads to the formation of phosphorylated H2AX foci, induction of Rad51 protein levels and ATM/ATR-dependent phosphorylation of p53. Inhibition of ATM/ATR kinases abolishes both induction of Rad51 and phosphorylation of p53, and remarkably reduces the level of apoptosis induced by co-expression of oncogenes and ARF. However, the induction of apoptosis is downregulated in p53-/- cells and does not depend on activities of ATM/ATR kinases, indicating that efficient induction of apoptosis by oncogene activation depends on coordinated action of ARF and ATM/ATR pathways in the regulation of p53

  3. Investigation of excimer ultraviolet sources from dielectric barrier discharge in krypton and halogen mixtures

    Science.gov (United States)

    Feng, Xiangfen; Zhu, Shaolong

    2006-09-01

    The characteristics of the emission spectra of Kr/Br2 and Kr/I2 mixtures driven by dielectric barrier discharge as a function of gas pressure were respectively investigated. It was found that the KrBr* excimer lamp provided an intense narrow band ultraviolet (UV) radiation at λ=207 nm, whose intensity was strongly influenced by gas pressure and buffer gas. The excimer radiation at λ=191 nm generated by the KrI* excimer lamp was very weak and less dependent on gas pressure due to predissociation which was confirmed by the strong emission of the atomic iodine line at λ=183 nm.

  4. E2F-dependent induction of p14ARF during cell cycle re-entry in human T cells

    DEFF Research Database (Denmark)

    del Arroyo, Ana Gutierrez; El Messaoudi, Selma; Clark, Paula A;

    2007-01-01

    other bona fide E2F target genes. This is accompanied by increased association of E2F1 with the endogenous ARF promoter. Our findings suggest that the ability of ARF to register normal proliferative cues depends on the levels of E2F generated in different settings and argue against the idea that it...

  5. The Solanum lycopersicum auxin response factor 7 (SlARF7) regulates auxin signaling during tomato fruit set and development.

    Science.gov (United States)

    de Jong, Maaike; Wolters-Arts, Mieke; Feron, Richard; Mariani, Celestina; Vriezen, Wim H

    2009-01-01

    Auxin response factors (ARFs) are encoded by a gene family of transcription factors that specifically control auxin-dependent developmental processes. A tomato ARF gene, homologous to Arabidopsis NPH4/ARF7 and therefore designated as Solanum lycopersicum ARF7 (SlARF7), was found to be expressed at a high level in unpollinated mature ovaries. More detailed analysis of tomato ovaries showed that the level of SlARF7 transcript increases during flower development, remains at a constant high level in mature flowers, and is down-regulated within 48 h after pollination. Transgenic plants with decreased SlARF7 mRNA levels formed seedless (parthenocarpic) fruits. These fruits were heart-shaped and had a rather thick pericarp due to increased cell expansion, compared with the pericarp of wild-type fruits. The expression analysis, together with the parthenocarpic fruit phenotype of the transgenic lines, suggests that, in tomato, SlARF7 acts as a negative regulator of fruit set until pollination and fertilization have taken place, and moderates the auxin response during fruit growth. PMID:18778404

  6. GBF1, a guanine nucleotide exchange factor for Arf, is crucial for coxsackievirus B3 RNA replication.

    NARCIS (Netherlands)

    Lanke, K.H.W.; Schaar, H.M. van der; Belov, G.A.; Feng, Q.; Duijsings, D.; Jackson, C.L.; Ehrenfeld, E.; Kuppeveld, F.J.M. van

    2009-01-01

    The replication of enteroviruses is sensitive to brefeldin A (BFA), an inhibitor of endoplasmic reticulum-to-Golgi network transport that blocks activation of guanine exchange factors (GEFs) of the Arf GTPases. Mammalian cells contain three BFA-sensitive Arf GEFs: GBF1, BIG1, and BIG2. Here, we show

  7. Molecular mechanisms of Sar/Arf GTPases in vesicular trafficking in yeast and plants

    Directory of Open Access Journals (Sweden)

    Tomohiro eYorimitsu

    2014-08-01

    Full Text Available Small GTPase proteins play essential roles in the regulation of vesicular trafficking systems in eukaryotic cells. Two types of small GTPases, secretion-associated Ras-related protein (Sar and ADP-ribosylation factor (Arf, act in the biogenesis of transport vesicles. Sar/Arf GTPases function as molecular switches by cycling between active, GTP-bound and inactive, GDP-bound forms, catalyzed by guanine nucleotide exchange factors and GTPase-activating proteins, respectively. Activated Sar/Arf GTPases undergo a conformational change, exposing the N-terminal amphipathic α-helix for insertion into membranes. The process triggers the recruitment and assembly of coat proteins to the membranes, followed by coated vesicle formation and scission. In higher plants, Sar/Arf GTPases also play pivotal roles in maintaining the dynamic identity of organelles in the secretory pathway. Sar1 GTPase strictly controls anterograde transport from the endoplasmic reticulum (ER through the recruitment of plant COPII coat components onto membranes. COPII vesicle transport is responsible for the organization of highly conserved polygonal ER networks. In contrast, Arf GTPases contribute to the regulation of multiple trafficking routes, including transport through the Golgi complex and endocytic transport. These transport systems have diversified in the plant kingdom independently and exhibit several plant-specific features with respect to Golgi organization, endocytic cycling, cell polarity and cytokinesis. The functional diversification of vesicular trafficking systems ensures the multicellular development of higher plants. This review focuses on the current knowledge of Sar/Arf GTPases, highlighting the molecular details of GTPase regulation in vesicle formation in yeast and advances in knowledge of the characteristics of vesicle trafficking in plants.

  8. Laser atherectomy in the treatment of peripheral arterial occlusive disease

    Czech Academy of Sciences Publication Activity Database

    Randula, A.; Thieme, M.; Schwenk, M.; Veverková, L.; Číp, Ondřej; Buchta, Zdeněk

    Elsevier. Vol. 9, Suppl. 1 (2012), S8. ISSN 1572-1000. [Photodiagnostics and Photodynamics Therapy. International Congress. 24.08.2012-29.08.2012, Helsinki] R&D Projects: GA MŠk ED0017/01/01 Institutional support: RVO:68081731 Keywords : excimer pulse laser * peripheral arterial occlusive disease Subject RIV: BH - Optics, Masers, Lasers

  9. Laser deposition and patterning of high-temperature superconductors

    International Nuclear Information System (INIS)

    Superconducting films of Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O on (100) SrTiO3 and (100) MgO substrates have been fabricated by reactive excimer-laser sputtering from ceramic targets. Film patterning by laser-induced reduction/metallization, oxidation, and ablation has been investigated

  10. Laser stimulated extraction of Pd from solution with uranyl

    International Nuclear Information System (INIS)

    Have been investigated process of the extraction of metal palladium from solution Pd2+HClO4+(UO22+) by radiation excimer XeCl-laser (λ=308 nm). By optimal parameters of solution efficiency of extraction was about 100%. Have been discussed processes reduction of palladium by resonance laser action. (author)

  11. Alternate laser fusion drivers

    International Nuclear Information System (INIS)

    Over the past few years, several laser systems have been considered as possible laser fusion drivers. Recently, there has been an increasing effort to evaluate these systems in terms of a reactor driver application. The specifications for such a system have become firmer and generally more restrictive. Several of the promising candidates such as the group VI laser, the metal vapor excimers and some solid state lasers can be eliminated on the basis of inefficiency. New solid state systems may impact the long range development of a fusion driver. Of the short wavelength gas lasers, the KrF laser used in conjunction with Raman compression and pulse stacking techniques is the most promising approach. Efficiencies approaching 10% may be possible with this system. While technically feasible, these approaches are complex and costly and are unsatisfying in an aethetic sense. A search for new lasers with more compelling features is still needed

  12. GTPase activity and neuronal toxicity of Parkinson's disease-associated LRRK2 is regulated by ArfGAP1.

    Directory of Open Access Journals (Sweden)

    Klodjan Stafa

    Full Text Available Mutations in the leucine-rich repeat kinase 2 (LRRK2 gene are the most common cause of autosomal dominant familial Parkinson's disease (PD and also contribute to idiopathic PD. LRRK2 encodes a large multi-domain protein with GTPase and kinase activity. Initial data indicates that an intact functional GTPase domain is critically required for LRRK2 kinase activity. PD-associated mutations in LRRK2, including the most common G2019S variant, have variable effects on enzymatic activity but commonly alter neuronal process morphology. The mechanisms underlying the intrinsic and extrinsic regulation of LRRK2 GTPase and kinase activity, and the pathogenic effects of familial mutations, are incompletely understood. Here, we identify a novel functional interaction between LRRK2 and ADP-ribosylation factor GTPase-activating protein 1 (ArfGAP1. LRRK2 and ArfGAP1 interact in vitro in mammalian cells and in vivo in brain, and co-localize in the cytoplasm and at Golgi membranes. PD-associated and functional mutations that alter the GTPase activity of LRRK2 modulate the interaction with ArfGAP1. The GTP hydrolysis activity of LRRK2 is markedly enhanced by ArfGAP1 supporting a role for ArfGAP1 as a GTPase-activating protein for LRRK2. Unexpectedly, ArfGAP1 promotes the kinase activity of LRRK2 suggesting a potential role for GTP hydrolysis in kinase activation. Furthermore, LRRK2 robustly and directly phosphorylates ArfGAP1 in vitro. Silencing of ArfGAP1 expression in primary cortical neurons rescues the neurite shortening phenotype induced by G2019S LRRK2 overexpression, whereas the co-expression of ArfGAP1 and LRRK2 synergistically promotes neurite shortening in a manner dependent upon LRRK2 GTPase activity. Neurite shortening induced by ArfGAP1 overexpression is also attenuated by silencing of LRRK2. Our data reveal a novel role for ArfGAP1 in regulating the GTPase activity and neuronal toxicity of LRRK2; reciprocally, LRRK2 phosphorylates ArfGAP1 and is

  13. INK4/ARF Transcript Expression Is Associated with Chromosome 9p21 Variants Linked to Atherosclerosis

    OpenAIRE

    Liu, Yan; Sanoff, Hanna K.; Cho, Hyunsoon; Burd, Christin E.; Torrice, Chad; Mohlke, Karen L.; Ibrahim, Joseph G.; Thomas, Nancy E.; Sharpless, Norman E.

    2009-01-01

    Background Genome-wide association studies (GWAS) have linked common single nucleotide polymorphisms (SNPs) on chromosome 9p21 near the INK4/ARF (CDKN2A/B) tumor suppressor locus with risk of atherosclerotic diseases and type 2 diabetes mellitus. To explore the mechanism of this association, we investigated whether expression of proximate transcripts (p16INK4a , p15INK4b , ARF, ANRIL and MTAP) correlate with genotype of representative 9p21 SNPs. Methodology/Principal Findings We analyzed expr...

  14. Deposition and characterization of ITO films produced by laser ablation at 355 nm

    DEFF Research Database (Denmark)

    Holmelund, E.; Thestrup Nielsen, Birgitte; Schou, Jørgen;

    2002-01-01

    Indium tin oxide (ITO) films have been deposited by pulsed laser deposition (PLD) at 355 nm. Even though the absorption of laser light at the wavelength 355 nm is much smaller than that of the standard excimer lasers for PLD at 248 nm and 193 nm, high-quality films can be produced. At high fluence...

  15. The spatial thickness distribution of metal films produced by large area pulsed laser deposition

    DEFF Research Database (Denmark)

    Pryds, Nini; Schou, Jørgen; Linderoth, Søren

    2007-01-01

    Thin films of metals have been deposited in the large-area Pulsed Laser Deposition (PLD) Facility at Riso National Laboratory. Thin films of Ag and Ni were deposited with laser pulses from an excimer laser at 248 nm with a rectangular beam spot at a fluence of 10 J/cm(2) on glass substrates of 127...

  16. Selective metallization of alumina by laser

    NARCIS (Netherlands)

    Shrivastva, P.B.; Boose, C.A.; Kolster, B.H.; Harteveld, C.; Meinders, B.

    1991-01-01

    Nickel has been selectively deposited on an alumina substrate without any pretreatment from a flow of a nickel acetate solution using the focused beam of an excimer laser. Nickel spots as well as nickel lines were drawn and subsequently plated with an electroless Ni-B coating. Excellent adhesion of

  17. Development of Solid State Laser Technology

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Byung Heon; Kwon, Seong Ok; Kim, Yong Ki (and others)

    2007-04-15

    Recently, diode-pumped solid state lasers(DPSSL) have been developed to have a diffraction limited beam quality and high average output powers beyond kW. The lifetime extends to have several thousand hours. Due to such merits, the DPSSLs are now replacing previous application fields of CO{sub 2} laser, lamp-pumped solid-state lasers, Excimer laser, etc. The DPSSLs have broad application fields, such as laser spectroscopy and analysis, laser micromachining, precision measurement, laser range findings, laser pump sources, medical lasers, etc. In this project, various DPSSLs are developed for use in laser isotope production. Many new laser modules are designed and used to develop high power pulsed IR lasers and green lasers. In addition, a quasi CW driven compact DPSSL is developed to have high pulse energy DPSSL technologies.

  18. Development of Solid State Laser Technology

    International Nuclear Information System (INIS)

    Recently, diode-pumped solid state lasers(DPSSL) have been developed to have a diffraction limited beam quality and high average output powers beyond kW. The lifetime extends to have several thousand hours. Due to such merits, the DPSSLs are now replacing previous application fields of CO2 laser, lamp-pumped solid-state lasers, Excimer laser, etc. The DPSSLs have broad application fields, such as laser spectroscopy and analysis, laser micromachining, precision measurement, laser range findings, laser pump sources, medical lasers, etc. In this project, various DPSSLs are developed for use in laser isotope production. Many new laser modules are designed and used to develop high power pulsed IR lasers and green lasers. In addition, a quasi CW driven compact DPSSL is developed to have high pulse energy DPSSL technologies

  19. Fabrication of Polymer Waveguides by Laser Ablation Using a 355 nm Wavelength Nd:YAG Laser

    OpenAIRE

    Zakariyah, S. S.; Conway, P. P.; Hutt, D.A.; Selviah, D. R.; K. Wang; Rygate, J.; Calver, J.; Kandulski, W.

    2011-01-01

    The demand for optical waveguides integrated into Printed Circuit Boards (PCBs) is increasing as the limitations of copper interconnects for greater than 10 Gb/s data rates are being reached. Optical polymer materials offer a good solution due to their relatively low cost and compatibility with traditional PCB manufacturing processes. Laser ablation is one method of manufacture, for which excimer lasers have been used, but UV Nd:YAG (Neodymium-doped Yttrium Aluminium Garnet) lasers are an att...

  20. Influence of gas discharge parameters on emissions from a dielectric barrier discharge excited argon excimer lamp

    OpenAIRE

    Mike Collier; Erich Rohwer; Timo Stehmann; Hubertus M. von Bergmann; Dumisani J. Hlatywayo; Peter Baricholo

    2011-01-01

    A dielectric barrier discharge excited neutral argon (Ar I) excimer lamp has been developed and characterised. The aim of this study was to develop an excimer lamp operating at atmospheric pressure that can replace mercury lamps and vacuum equipment used in the sterilisation of medical equipment and in the food industry. The effects of discharge gas pressure, flow rate, excitation frequency and pulse width on the intensity of the Ar I vacuum ultraviolet (VUV) emission at 126 nm and near infra...

  1. The DNA damage checkpoint precedes activation of ARF in response to escalating oncogenic stress during tumorigenesis

    Czech Academy of Sciences Publication Activity Database

    Evangelou, K.; Bartkova, J.; Kotsinas, A.; Pateras, I.S.; Liontos, M.; Velimezi, G.; Košař, Martin; Liloglou, T.; Trougakos, I.P.; Dyrskjot, L.; Andersen, C.J.; Papaioannou, G.; Drosos, A.; Papafotiou, M.; Hodný, Zdeněk; Sosa-Pineda, B.; Wu, X.R.; Klinakis, A.; Orntoft, T.; Lukas, J.; Bartek, Jiří; Gorgoulis, V.G.

    2013-01-01

    Roč. 20, č. 11 (2013), s. 1485-1497. ISSN 1350-9047 Institutional support: RVO:68378050 Keywords : ARF * carcinogenesis * DDR * E2F1 * p16(INK4A) Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 8.385, year: 2013

  2. Illuga saga Gríðarfóstra in Sweden

    DEFF Research Database (Denmark)

    Lavender, Philip Thomas

    2014-01-01

    This article looks at the intellectual history behind and scholarly preparation towards the first edition of Illuga saga Gríðarfóstra in Sweden in 1695. One of the main questions which the article tries to answer is why an edition of a saga about Danish kings and heroes would end up being produce...

  3. Whatever Happened to Illuga saga Gríðarfóstra?

    DEFF Research Database (Denmark)

    Lavender, Philip Thomas

    Never heard of Illuga saga Gríðarfóstra? You’re not alone. Alongside the canon of world literary treasures there lies a shady world of forgotten and abandoned texts. The focus of my doctoral research has been the revindication of one such work, not simply because humanities research revels in the...

  4. Nucleophosmin is required for DNA integrity and p19Arf protein stability

    DEFF Research Database (Denmark)

    Colombo, Emanuela; Bonetti, Paola; Lazzerini Denchi, Eros;

    2005-01-01

    Nucleophosmin (NPM) is a nucleolar phosphoprotein that binds the tumor suppressors p53 and p19(Arf) and is thought to be indispensable for ribogenesis, cell proliferation, and survival after DNA damage. The NPM gene is the most frequent target of genetic alterations in leukemias and lymphomas, th...

  5. Rab, Arf, and Arl-Regulated Membrane Traffic in Cortical Neuron Migration.

    Science.gov (United States)

    Tang, Bor Luen

    2016-07-01

    The migration of projection neurons from its birthplace in the subventricular zone to their final destination in the cortical plate is a complex process that requires a series of highly coordinated cellular events. Amongst the key factors involved in the processes are modulators of cytoskeletal dynamics, as well as cellular membrane traffic. Members of the small GTPases family responsible for the latter process, the Rabs and Arfs, have been recently implicated in cortical neuron migration. Rab5 and Rab11, which are key modulators of endocytosis and endocytic recycling respectively, ensure proper surface expression and distribution of N-cadherin, a key adhesion protein that tethers migrating neurons to the radial glia fiber tracts during pia-directed migration. Rab7, which is associated with lysosomal biogenesis and function, is important for the final step of terminal translocation when N-cadherin is downregulated by lysosomal degradation. Arf6 activity, which is known to be important in neuronal processes outgrowth, may negatively impact the multipolar-bipolar transition of cortical neurons undergoing radial migration, but the downstream effector of Arf6 in this regard is not yet known. In addition to the above, members of the Arl family which have been recently shown to be important in radial glia scaffold formation, would also be important for cortical neuron migration. In this short review, we discuss recent advances in our understanding of the importance of membrane traffic regulated by the Rab, Arf, and Arl family members in cortical neuron migration. PMID:26587959

  6. The ARF-like 2 (ARL2)-binding protein, BART. Purification, cloning, and initial characterization.

    Science.gov (United States)

    Sharer, J D; Kahn, R A

    1999-09-24

    ARF-like proteins (ARLs) comprise a functionally distinct group of incompletely characterized members in the ARF family of RAS-related GTPases. We took advantage of the GTP binding characteristics of human ARL2 to develop a specific, high affinity binding assay that allowed the purification of a novel ARL2-binding protein. A 19-kDa protein (BART, Binder of Arl Two) was identified and purified from bovine brain homogenate. BART binding is specific to ARL2.GTP with high affinity but does not interact with ARL2.GDP or activated ARF or RHO proteins. Based on peptide sequences of purified bovine BART, the human cDNA sequence was determined. The 489-base pair BART open reading frame encodes a novel 163-amino acid protein with a predicted molecular mass of 18,822 Da. Recombinant BART was found to bind ARL2.GTP in a manner indistinguishable from native BART. Northern and Western analyses indicated BART is expressed in all tissues sampled. The lack of detectable membrane association of ARL2 or BART upon activation of ARL2 is suggestive of actions quite distinct from those of the ARFs. The lack of ARL2 GTPase-activating protein activity in BART led us to conclude that the specific interaction with ARL2.GTP is most consistent with BART being the first identified ARL2-specific effector. PMID:10488091

  7. Formation and control of excimer of a coumarin derivative in Langmuir–Blodgett films

    Energy Technology Data Exchange (ETDEWEB)

    Chakraborty, Santanu; Bhattacharjee, D.; Hussain, Syed Arshad, E-mail: sa_h153@hotmail.com

    2014-01-15

    In this communication we report the formation and control of excimer of a coumerin derivative 7-Hydroxy-N-Octadecyl Coumarin-3-Carboxamide (7HNO3C) assembled onto Langmuir–Blodgett (LB) films. Surface pressure–area per molecule isotherm revealed that 7HNO3C formed stable Langmuir monolayer at the air–water interface. Spectroscoipic characterizations confirmed the formation of excimer of 7HNO3C in the LB film prepared at 20 mN/m surface pressure. The excimer band remains present even when 7HNO3C molecules are diluted with a long chain fatty acid stearic acid in LB films. The excimer formation of 7HNO3C can be controlled by incorporating clay particle laponite in the LB film. The excimer band is totally absent in the hybrid 7HNO3C–laponite LB films. In-situ fluorescence imaging microscopy and atomic force microscopy confirmed the incorporation of clay laponite onto LB films. -- Highlights: • Formation of Langmuir monolayer and Langmuir–Blodgett (LB) film of a coumarin derivative. • Presence of excimeric species in the LB film lifted at 20 mN/m surface pressure is confirmed from the spectroscopic studies. • Control of excimer formation by incorporating clay particle laponite on to the LB film. • In-situ fluorescence imaging microscopy and atomic force microscopy confirmed the incorporation of clay laponite onto LB films.

  8. Immersion and dry ArF scanners enabling 22nm HP production and beyond

    Science.gov (United States)

    Uehara, Yusaku; Ishikawa, Jun; Kohno, Hirotaka; Tanaka, Eiichiro; Ohba, Masanori; Shibazaki, Yuichi

    2012-03-01

    Pattern shrinks using multiple patterning techniques will continue to the 22nm half pitch (HP) node and beyond. The cutting-edge Nikon NSR-S621D immersion lithography tool, which builds upon the technology advancements of the NSR-S620D [1], was developed to satisfy the aggressive requirements for the 22 nm HP node and subsequent generations. The key design challenge for the S621D was to deliver further improvements to product overlay performance and CD uniformity, while also providing increased productivity. Since many different products are made within an IC manufacturing facility, various wafer process-related issues, including the flatness or grid distortion of the processed wafers and exposure-induced heating had to be addressed. Upgrades and enhancements were made to the S620D hardware and software systems to enable the S621D to minimize these process-related effects and deliver the necessary scanner performance. To enable continued process technology advancements, in addition to pattern shrinks at the most critical layers, resolution for less critical layers must also be improved proportionally. As a result, increased demand for dry ArF instead of KrF scanners is expected for less critical layers, and dry ArF tools are already being employed for some of these applications. Further, multiple patterning techniques, such as sidewall double patterning, actually enable use of dry ArF instead of immersion scanners for some critical layers having relaxed pattern resolution requirements. However, in order for this to be successful, the ArF dry tool must deliver overlay performance that is comparable to the latest generation immersion systems. Understanding these factors, an ArF dry scanner that has excellent overlay performance could be used effectively for critical layers and markedly improve cost of ownership (CoO). Therefore, Nikon has developed the NSR-S320F, a new dry ArF scanner also built upon the proven S620D Streamlign platform. By incorporating the

  9. Which Way In? The RalF Arf-GEF Orchestrates Rickettsia Host Cell Invasion.

    Directory of Open Access Journals (Sweden)

    Kristen E Rennoll-Bankert

    2015-08-01

    Full Text Available Bacterial Sec7-domain-containing proteins (RalF are known only from species of Legionella and Rickettsia, which have facultative and obligate intracellular lifestyles, respectively. L. pneumophila RalF, a type IV secretion system (T4SS effector, is a guanine nucleotide exchange factor (GEF of ADP-ribosylation factors (Arfs, activating and recruiting host Arf1 to the Legionella-containing vacuole. In contrast, previous in vitro studies showed R. prowazekii (Typhus Group RalF is a functional Arf-GEF that localizes to the host plasma membrane and interacts with the actin cytoskeleton via a unique C-terminal domain. As RalF is differentially encoded across Rickettsia species (e.g., pseudogenized in all Spotted Fever Group species, it may function in lineage-specific biology and pathogenicity. Herein, we demonstrate RalF of R. typhi (Typhus Group interacts with the Rickettsia T4SS coupling protein (RvhD4 via its proximal C-terminal sequence. RalF is expressed early during infection, with its inactivation via antibody blocking significantly reducing R. typhi host cell invasion. For R. typhi and R. felis (Transitional Group, RalF ectopic expression revealed subcellular localization with the host plasma membrane and actin cytoskeleton. Remarkably, R. bellii (Ancestral Group RalF showed perinuclear localization reminiscent of ectopically expressed Legionella RalF, for which it shares several structural features. For R. typhi, RalF co-localization with Arf6 and PI(4,5P2 at entry foci on the host plasma membrane was determined to be critical for invasion. Thus, we propose recruitment of PI(4,5P2 at entry foci, mediated by RalF activation of Arf6, initiates actin remodeling and ultimately facilitates bacterial invasion. Collectively, our characterization of RalF as an invasin suggests that, despite carrying a similar Arf-GEF unknown from other bacteria, different intracellular lifestyles across Rickettsia and Legionella species have driven divergent roles

  10. A novel proapoptotic gene PANO encodes a post-translational modulator of the tumor suppressor p14ARF

    Energy Technology Data Exchange (ETDEWEB)

    Watari, Akihiro; Li, Yang; Higashiyama, Shinji; Yutsudo, Masuo, E-mail: yutsudo@biken.osaka-u.ac.jp

    2012-02-01

    The protein p14ARF is a known tumor suppressor protein controlling cell proliferation and survival, which mainly localizes in nucleoli. However, the regulatory mechanisms that govern its activity or expression remain unclear. Here, we report that a novel proapoptotic nucleolar protein, PANO, modulates the expression and activity of p14ARF in HeLa cells. Overexpression of PANO enhances the stability of p14ARF protein by protecting it from degradation, resulting in an increase in p14ARF expression levels. Overexpression of PANO also induces apoptosis under low serum conditions. This effect is dependent on the nucleolar localization of PANO and inhibited by knocking-down p14ARF. Alternatively, PANO siRNA treated cells exhibit a reduction in p14ARF protein levels. In addition, ectopic expression of PANO suppresses the tumorigenicity of HeLa cells in nude mice. These results indicate that PANO is a new apoptosis-inducing gene by modulating the tumor suppressor protein, p14ARF, and may itself be a new candidate tumor suppressor gene.

  11. Correction of monochromatic aberrations in human eyes - report on work in progress

    International Nuclear Information System (INIS)

    In the excimer laser photorefractive keratectomy the laser removes tissues across the anterior corneal surface. The result is a change in the anterior corneal curvature which is used to correct ocular image errors such as myopia and astigmatism. Unfortunately, there are additional aberrations as higher order coma-like and spherical aberration-like image errors limiting the visual acuity. Actually we are investigating how to fit the excimer laser photorefractive ablation profiles for correction of myopia and astigmatism to those for minimizing higher order coma and spherical aberration. Our approach is an aberrometry-guided corneal refractive surgery using a scanning spot ArF excimer laser. (author)

  12. Capas de a-SiN:H modificadas mediante la irradiación con un láser de excímero

    OpenAIRE

    Banerji, N.; Serra, J; Chiussi, S.; Lusquiños, F.; León, B.; Pérez-Amor, M.

    1998-01-01

    Hydrogenated amorphous silicon nitride (a:SiN:H) films produced by CO2 and ArF laser-induced CVD in parallel configuration using silane/ammonia or disilane/ammonia gas mixtures were subjected to room temperature multiple pulse ArF excimer laser irradiations in an inert gas atmosphere. Modifications in their chemical composition, refractive index, and surface morphology were systematically followed up through Fourier-transform infrared spectroscopy (FTIR), energy dispers...

  13. Wheat tissue hardness. Application of laser-induced breakdown spectroscopy and chemometrics

    International Nuclear Information System (INIS)

    Complete text of publication follows. Wheat grain is a complex structure made of the germ and starchy endosperm surrounded by several peripheral tissues differing in their structure and chemical compositions. In traditional wheat milling processes, this part of the grain is discarded as the bran, mostly used in animal feed. Bran could be however used for food ingredient preparation if it is fractionated to remove unwanted parts and increase bioactive compounds accessibility. Wheat outer layers mechanical properties are key properties to explain differences observed for bran fractionation. Up to now, these properties are deduced by tensile tests of hand-isolated tissues after wheat humidification, a procedure that could induce artefacts. Pulsed laser ablation have demonstrated a potential technique to reveal wheat tissue properties (Martelli et al., J Cereal Sci, in press.). Ablation rate was deduced from microscopic observations which are time consuming. Taking advantage of compositional heterogeneity within the peripheral tissues, laser-induced breakdown spectroscopy (LIBS) could be a powerful tool to follow wheat tissue ablation. With this aim, native grains of a soft common wheat (Crousty) were gradually ablated with a pulsed excimer laser ArF (193 nm, 15 ns, 1 Hz, 2 J · cm-2) coupled to a miniature optical fibre spectrometer. Spectra were acquired from each pulse. Chemometrics were successfully applied to exploit the complex LIBS spectral data. The bran tissues (pericarp, seed coat, aleurone layer) and the endosperm were successfully predicted by a partial least square discriminant analysis (PLS-DA) model. These results were validated by microscopic observations Tissue hardness was deduced from the ablation rate but also directly from LIBS spectra, by exploring the ionic to atomic magnesium line ratio (Mg II 279.55 nm/Mg I 285.22 nm). Tissue ablation rate were indirectly related to Mg II/Mg I, suggesting the LIBS potential to estimate tissue hardness. Even

  14. A population-based study on the association between acute renal failure (ARF and the duration of polypharmacy

    Directory of Open Access Journals (Sweden)

    Chang Yi-Ping

    2012-08-01

    Full Text Available Abstract Background Because of the rapid growth in elderly population, polypharmacy has become a serious public health issue worldwide. Although acute renal failure (ARF is one negative consequence of polypharmacy, the association between the duration of polypharmacy and ARF remains unclear. We therefore assessed this association using a population-based database. Methods Data were collected from the Taiwan National Health Insurance Research Database (NHIRD from 2003 through 2006. The case group included patients hospitalized for ARF during 2006, but not admitted due to trauma, surgery, burn trauma, car accident, transplantation, or infectious diseases; the control group included patients hospitalized without ARF. The cumulative number of days of polypharmacy (defined as more than 5 prescriptions per day for 1 year prior to admission was determined, with patients further subdivided into 4 categories: less than 30 days, 31–90 days, 91–180 days, and over 181 days. The dependent variable was ARF, and the control variables were age, gender, comorbidities in patients hospitalized for ARF, stay in ICUs during ARF hospitalization and site of operation for prior admissions within one month of ARF hospitalization. Results Of 20,790 patients who were admitted to hospitals for ARF in 2006, 12,314 (59.23 % were male and more than 60 % were older than 65 years. Of patients with and without ARF, 16.14 % and 10.61 %, respectively, received polypharmacy for 91–180 days and 50.22 % and 24.12 %, respectively, for over 181 days. A statistical model indicated that, relative to patients who received polypharmacy for less than 30 days, those who received polypharmacy for 31–90, 91–180 and over 181 days had odds ratios of developing ARF of 1.33 (p Conclusions We observed statistically significant associations between the duration of polypharmacy and the occurrence of ARF.

  15. Prognostic value of the hDMP1-ARF-Hdm2-p53 pathway in breast cancer

    OpenAIRE

    Maglic, Dejan; Zhu, Sinan; Taneja, Pankaj; Fry, Elizabeth A.; Kai, Fumitake; Kendig, Robert D.; Sugiyama, Takayuki; Miller, Lance D.; Willingham, Mark C.; Inoue, Kazushi

    2012-01-01

    Our recent study showed critical roles of Dmp1 as a sensor of oncogenic Ras, HER2/neu signaling and activation of the Arf-p53 pathway. To elucidate the role of human DMP1 (hDMP1) in breast cancer, one hundred and ten pairs of human breast cancer specimen were studied for the alterations of the hDMP1-ARF-Hdm2-p53 pathway with follow up of clinical outcomes. Loss of heterozygosity (LOH) of the hDMP1 locus was found in 42% of human breast carcinomas, while that of INK4a/ARF and p53 were found in...

  16. Preliminary design and estimate of capital and operating costs for a production scale application of laser decontamination technology

    International Nuclear Information System (INIS)

    The application of laser ablation technology to the decontamination of radioactive metals, particularly the surfaces of equipment, is discussed. Included is information related to the design, capital and operating costs, and effectiveness of laser ablation technology, based on commercial excimer and Nd:YAG lasers, for the decontamination of production scale equipment

  17. Cancer cell specific cytotoxic gene expression mediated by ARF tumor suppressor promoter constructs

    International Nuclear Information System (INIS)

    Highlights: • ARF promoter showed higher responsiveness to deregulated E2F activity than the E2F1 promoter. • ARF promoter showed higher cancer cell-specificity than E2F1 promoter to drive gene expression. • HSV-TK driven by ARF promoter showed higher cancer cell-specific cytotoxicity than that driven by E2F1 promoter. - Abstract: In current cancer treatment protocols, such as radiation and chemotherapy, side effects on normal cells are major obstacles to radical therapy. To avoid these side effects, a cancer cell-specific approach is needed. One way to specifically target cancer cells is to utilize a cancer specific promoter to express a cytotoxic gene (suicide gene therapy) or a viral gene required for viral replication (oncolytic virotherapy). For this purpose, the selected promoter should have minimal activity in normal cells to avoid side effects, and high activity in a wide variety of cancers to obtain optimal therapeutic efficacy. In contrast to the AFP, CEA and PSA promoters, which have high activity only in a limited spectrum of tumors, the E2F1 promoter exhibits high activity in wide variety of cancers. This is based on the mechanism of carcinogenesis. Defects in the RB pathway and activation of the transcription factor E2F, the main target of the RB pathway, are observed in almost all cancers. Consequently, the E2F1 promoter, which is mainly regulated by E2F, has high activity in wide variety of cancers. However, E2F is also activated by growth stimulation in normal growing cells, suggesting that the E2F1 promoter may also be highly active in normal growing cells. In contrast, we found that the tumor suppressor ARF promoter is activated by deregulated E2F activity, induced by forced inactivation of pRB, but does not respond to physiological E2F activity induced by growth stimulation. We also found that the deregulated E2F activity, which activates the ARF promoter, is detected only in cancer cell lines. These observations suggest that ARF promoter

  18. Cancer cell specific cytotoxic gene expression mediated by ARF tumor suppressor promoter constructs

    Energy Technology Data Exchange (ETDEWEB)

    Kurayoshi, Kenta [Department of Bioscience, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337 (Japan); Ozono, Eiko [Centre for Molecular Oncology, Barts Cancer Institute, Queen Mary, University of London, John Vane Science Centre, Charterhouse Square, London EC1M 6BQ (United Kingdom); Iwanaga, Ritsuko; Bradford, Andrew P. [Department of Obstetrics and Gynecology, University of Colorado School of Medicine, Anschutz Medical Campus, 12800 East 19th Avenue, Aurora, CO 80045 (United States); Komori, Hideyuki [Center for Stem Cell Biology, Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109 (United States); Ohtani, Kiyoshi, E-mail: btm88939@kwansei.ac.jp [Department of Bioscience, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337 (Japan)

    2014-07-18

    Highlights: • ARF promoter showed higher responsiveness to deregulated E2F activity than the E2F1 promoter. • ARF promoter showed higher cancer cell-specificity than E2F1 promoter to drive gene expression. • HSV-TK driven by ARF promoter showed higher cancer cell-specific cytotoxicity than that driven by E2F1 promoter. - Abstract: In current cancer treatment protocols, such as radiation and chemotherapy, side effects on normal cells are major obstacles to radical therapy. To avoid these side effects, a cancer cell-specific approach is needed. One way to specifically target cancer cells is to utilize a cancer specific promoter to express a cytotoxic gene (suicide gene therapy) or a viral gene required for viral replication (oncolytic virotherapy). For this purpose, the selected promoter should have minimal activity in normal cells to avoid side effects, and high activity in a wide variety of cancers to obtain optimal therapeutic efficacy. In contrast to the AFP, CEA and PSA promoters, which have high activity only in a limited spectrum of tumors, the E2F1 promoter exhibits high activity in wide variety of cancers. This is based on the mechanism of carcinogenesis. Defects in the RB pathway and activation of the transcription factor E2F, the main target of the RB pathway, are observed in almost all cancers. Consequently, the E2F1 promoter, which is mainly regulated by E2F, has high activity in wide variety of cancers. However, E2F is also activated by growth stimulation in normal growing cells, suggesting that the E2F1 promoter may also be highly active in normal growing cells. In contrast, we found that the tumor suppressor ARF promoter is activated by deregulated E2F activity, induced by forced inactivation of pRB, but does not respond to physiological E2F activity induced by growth stimulation. We also found that the deregulated E2F activity, which activates the ARF promoter, is detected only in cancer cell lines. These observations suggest that ARF promoter

  19. Selective metallization of alumina by laser

    OpenAIRE

    Shrivastva, P.B.; Boose, C.A.; Kolster, B.H.; Harteveld, C; Meinders, B.

    1991-01-01

    Nickel has been selectively deposited on an alumina substrate without any pretreatment from a flow of a nickel acetate solution using the focused beam of an excimer laser. Nickel spots as well as nickel lines were drawn and subsequently plated with an electroless Ni-B coating. Excellent adhesion of the metallized layers was achieved, since with laser irradiation, both etching and deposition took place simultaneously.

  20. Cancer cell specific cytotoxic gene expression mediated by ARF tumor suppressor promoter constructs.

    Science.gov (United States)

    Kurayoshi, Kenta; Ozono, Eiko; Iwanaga, Ritsuko; Bradford, Andrew P; Komori, Hideyuki; Ohtani, Kiyoshi

    2014-07-18

    In current cancer treatment protocols, such as radiation and chemotherapy, side effects on normal cells are major obstacles to radical therapy. To avoid these side effects, a cancer cell-specific approach is needed. One way to specifically target cancer cells is to utilize a cancer specific promoter to express a cytotoxic gene (suicide gene therapy) or a viral gene required for viral replication (oncolytic virotherapy). For this purpose, the selected promoter should have minimal activity in normal cells to avoid side effects, and high activity in a wide variety of cancers to obtain optimal therapeutic efficacy. In contrast to the AFP, CEA and PSA promoters, which have high activity only in a limited spectrum of tumors, the E2F1 promoter exhibits high activity in wide variety of cancers. This is based on the mechanism of carcinogenesis. Defects in the RB pathway and activation of the transcription factor E2F, the main target of the RB pathway, are observed in almost all cancers. Consequently, the E2F1 promoter, which is mainly regulated by E2F, has high activity in wide variety of cancers. However, E2F is also activated by growth stimulation in normal growing cells, suggesting that the E2F1 promoter may also be highly active in normal growing cells. In contrast, we found that the tumor suppressor ARF promoter is activated by deregulated E2F activity, induced by forced inactivation of pRB, but does not respond to physiological E2F activity induced by growth stimulation. We also found that the deregulated E2F activity, which activates the ARF promoter, is detected only in cancer cell lines. These observations suggest that ARF promoter is activated by E2F only in cancer cells and therefore may be more cancer cell-specific than E2F1 promoter to drive gene expression. We show here that the ARF promoter has lower activity in normal growing fibroblasts and shows higher cancer cell-specificity compared to the E2F1 promoter. We also demonstrate that adenovirus expressing HSV