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Sample records for 8-inch-diameter fused silica

  1. Design and performance of a parachute recovery system to recover 155-mm- and 8-inch-diameter artillery shells

    SciTech Connect

    Waye, D.E.; Peterson, C.W.; Botner, W.T.

    1986-01-01

    A parachute recovery system has been developed and demonstrated for the recovery of 155-mm- and 8-inch-diameter artillery shells. The recovery system functions after being subjected to gun launch accelerations of up to 18,000 g's axially and up to 400,000 rad/sec/sup 2/ radially. The parachute is deployed while the shell is still spinning at about 250 revolutions per second. To deploy the parachute while the shell is spinning, a double-swivel system was developed. The deployment signal for the recovery system is provided by an electronic timer. Over 250 tests have been performed on both the 155-mm- and 8-inch-diameter artillery shell. Impact velocities are between 100 and 120 feet per second. The latest version of the recovery systems has been proven to be over 95% successful for the recovery of 8-inch-diameter artillery shells and over 85% successful for the recovery of 155-mm-diameter artillery shells.

  2. Fused Silica and Other Transparent Window Materials

    NASA Technical Reports Server (NTRS)

    Salem, Jon

    2016-01-01

    Several transparent ceramics, such as spinel and AlONs are now being produced in sufficient large areas to be used in space craft window applications. The work horse transparent material for space missions from Apollo to the International Space Station has been fused silica due in part to its low coefficient of expansion and optical quality. Despite its successful use, fused silica exhibits anomalies in its crack growth behavior, depending on environmental preconditioning and surface damage. This presentation will compare recent optical ceramics to fused silica and discuss sources of variation in slow crack growth behavior.

  3. Fluorine-Based DRIE of Fused Silica

    NASA Technical Reports Server (NTRS)

    Yee, Karl; Shcheglov, Kirill; Li, Jian; Choi, Daniel

    2007-01-01

    A process of deep reactive-ion etching (DRIE) using a fluorine-based gas mixture enhanced by induction-coupled plasma (ICP) has been demonstrated to be effective in forming high-aspect-ratio three-dimensional patterns in fused silica. The patterns are defined in part by an etch mask in the form of a thick, high-quality aluminum film. The process was developed to satisfy a need to fabricate high-aspect-ratio fused-silica resonators for vibratory microgyroscopes, and could be used to satisfy similar requirements for fabricating other fused-silica components.

  4. Fused silica windows for solar receiver applications

    NASA Astrophysics Data System (ADS)

    Hertel, Johannes; Uhlig, Ralf; Söhn, Matthias; Schenk, Christian; Helsch, Gundula; Bornhöft, Hansjörg

    2016-05-01

    A comprehensive study of optical and mechanical properties of quartz glass (fused silica) with regard to application in high temperature solar receivers is presented. The dependence of rupture strength on different surface conditions as well as high temperature is analyzed, focussing particularly on damage by devitrification and sandblasting. The influence of typical types of contamination in combination with thermal cycling on the optical properties of fused silica is determined. Cleaning methods are compared regarding effectiveness on contamination-induced degradation for samples with and without antireflective coating. The FEM-aided design of different types of receiver windows and their support structure is presented. A large-scale production process has been developed for producing fused silica dome shaped windows (pressurized window) up to a diameter of 816 mm. Prototypes were successfully pressure-tested in a test bench and certified according to the European Pressure Vessel Directive.

  5. Transmitting and reflecting diffuser. [using ultraviolet grade fused silica coatings

    NASA Technical Reports Server (NTRS)

    Keafer, L. S., Jr.; Burcher, E. E.; Kopia, L. P. (Inventor)

    1977-01-01

    An ultraviolet grade fused silica substrate is coated with vaporized fused silica. The coating thickness is controlled, one thickness causing ultraviolet light to diffuse and another thickness causing ultraviolet light to reflect a near Lambertian pattern.

  6. Quartz/fused silica chip carriers

    NASA Technical Reports Server (NTRS)

    1992-01-01

    The primary objective of this research and development effort was to develop monolithic microwave integrated circuit (MMIC) packaging which will operate efficiently at millimeter-wave frequencies. The packages incorporated fused silica as the substrate material which was selected due to its favorable electrical properties and potential performance improvement over more conventional materials for Ka-band operation. The first step towards meeting this objective is to develop a package that meets standard mechanical and thermal requirements using fused silica and to be compatible with semiconductor devices operating up to at least 44 GHz. The second step is to modify the package design and add multilayer and multicavity capacity to allow for application specific integrated circuits (ASIC's) to control multiple phase shifters. The final step is to adapt the package design to a phased array module with integral radiating elements. The first task was a continuation of the SBIR Phase 1 work. Phase 1 identified fused silica as a viable substrate material by demonstrating various plating, machining, and adhesion properties. In Phase 2 Task 1, a package was designed and fabricated to validate these findings. Task 2 was to take the next step in packaging and fabricate a multilayer, multichip module (MCM). This package is the predecessor to the phased array module and demonstrates the ability to via fill, circuit print, laminate, and to form vertical interconnects. The final task was to build a phased array module. The radiating elements were to be incorporated into the package instead of connecting to it with wire or ribbon bonds.

  7. Laser Damage Precursors in Fused Silica

    SciTech Connect

    Miller, P; Suratwala, T; Bude, J; Laurence, T A; Shen, N; Steele, W A; Feit, M; Menapace, J; Wong, L

    2009-11-11

    There is a longstanding, and largely unexplained, correlation between the laser damage susceptibility of optical components and both the surface quality of the optics, and the presence of near surface fractures in an optic. In the present work, a combination of acid leaching, acid etching, and confocal time resolved photoluminescence (CTP) microscopy has been used to study laser damage initiation at indentation sites. The combination of localized polishing and variations in indentation loads allows one to isolate and characterize the laser damage susceptibility of densified, plastically flowed and fractured fused silica. The present results suggest that: (1) laser damage initiation and growth are strongly correlated with fracture surfaces, while densified and plastically flowed material is relatively benign, and (2) fracture events result in the formation of an electronically defective rich surface layer which promotes energy transfer from the optical beam to the glass matrix.

  8. Fused silica challenges in sensitive space applications

    NASA Astrophysics Data System (ADS)

    Criddle, Josephine; Nürnberg, Frank; Sawyer, Robert; Bauer, Peter; Langner, Andreas; Schötz, Gerhard

    2016-07-01

    Space bound as well as earthbound spectroscopy of extra-terrestrial objects finds its challenge in light sources with low intensities. High transmission for every optical element along the light path requires optical materials with outstanding performance to enable the measurement of even a one-photon event. Using the Lunar Laser Ranging Project and the LIGO and VIRGO Gravitational Wave Detectors as examples, the influence of the optical properties of fused silica will be described. The Visible and Infrared Surveillance Telescope for Astronomy (VISTA) points out the material behavior in the NIR regime, where the chemical composition of optical materials changes the performance. Special fibers are often used in combination with optical elements as light guides to the spectroscopic application. In an extended spectral range between 350 and 2,200 nm Heraeus developed STU fiber preforms dedicated for broad band spectroscopy in astronomy. STU fibers in the broad spectral range as well as SSU fibers for UV transmission (180 - 400 nm) show also high gamma radiation resistance which allows space applications.

  9. Coated Fused Silica Fibers for Enhanced Sensitivity Torsion Pendulum

    NASA Technical Reports Server (NTRS)

    Numata, Kenji; Horowitz, Jordan; Camp, Jordan

    2007-01-01

    In order to investigate the fundamental thermal noise limit of a torsion pendulum using a fused silica fiber, we systematically measured and modeled the mechanical losses of thin fused silica fibers coated by electrically conductive thin metal films. Our results indicate that it is possible to achieve a thermal noise limit for coated silica lower by a factor between 3 and 9, depending on the silica diameter, compared to the best tungsten fibers available. This will allow a corresponding increase in sensitivity of torsion pendula used for weak force measurements, including the gravitational constant measurement and ground-based force noise testing for the Laser Interferometer Space Antenna (LISA) mission.

  10. Quantification of residual stress from photonic signatures of fused silica

    NASA Astrophysics Data System (ADS)

    Cramer, K. Elliott; Hayward, Maurice; Yost, William T.

    2014-02-01

    A commercially available grey-field polariscope (GFP) instrument for photoelastic examination is used to assess impact damage inflicted upon the outer-most pane of Space Shuttle windows made from fused silica. A method and apparatus for calibration of the stress-optic coefficient using four-point bending is discussed. The results are validated on known material (acrylic) and are found to agree with literature values to within 6%. The calibration procedure is then applied to fused-silica specimens and the stress-optic coefficient is determined to be 2.43 ± 0.54 × 10-12 Pa-1. Fused silica specimens containing impacts artificially made at NASA's Hypervelocity Impact Technology Facility (HIT-F), to simulate damage typical during space flight, are examined. The damage sites are cored from fused silica window carcasses and examined with the GFP. The calibrated GFP measurements of residual stress patterns surrounding the damage sites are presented.

  11. Global equation of state for a glassy material: Fused silica

    SciTech Connect

    Boettger, J.C.

    1994-09-01

    A new SESAME equation of state (EOS) for fused silica has been generated using the computer program GRIZZLY and will be added to the SESAME library as material number 7387. This new EOS provides better agreement with experimental data than was achieved by all previous SESAME EOSs for fused silica. Material number 7387 also constitutes the most realistic SESAME-type EOS generated for any glassy material thus far.

  12. Fused silica reflecting heat shields for outer planet entry probes

    NASA Technical Reports Server (NTRS)

    Congdon, W. M.; Peterson, D. L.

    1975-01-01

    The development of slip-cast fused silica is discussed as a heat shield designed to meet the needs of outer-planet entry probes. The distinguishing feature of silica is its ability to reflect the radiation imposed by planetary-entry environments. This reflectivity is particularly sensitive to degradation by the presence of trace amounts of contaminants introduced by the starting materials or by processing. The microstructure of a silica configuration also significantly influences the reflectivity and other thermomechanical properties. The processing techniques attendant on controlling microstructure while maintaining purity are discussed. The selection of a starting material of essential purity precludes the use of purified natural quartz and requires the use of synthetic fused silica. The silica is characterized in a limited combined heating test environment. The surface mass loss is controlled by liquid runoff from a relatively low-temperature melt layer; the reflectance is basically maintained and the material achieves a surprisingly high heat of ablation.

  13. Quantification of Residual Stress from Photonic Signatures of Fused Silica

    NASA Technical Reports Server (NTRS)

    Cramer, K. Elliott; Hayward, Maurice; Yost, William E.

    2013-01-01

    A commercially available grey-field polariscope (GFP) instrument for photoelastic examination is used to assess impact damage inflicted upon the outer-most pane of Space Shuttle windows made from fused silica. A method and apparatus for calibration of the stress-optic coefficient using four-point bending is discussed. The results are validated on known material (acrylic) and are found to agree with literature values to within 6%. The calibration procedure is then applied to fused-silica specimens and the stress-optic coefficient is determined to be 2.43 +/- 0.54 x 10(exp -12)/Pa. Fused silica specimens containing impacts artificially made at NASA's Hypervelocity Impact Technology Facility (HIT-F), to simulate damage typical during space flight, are examined. The damage sites are cored from fused silica window carcasses and examined with the GFP. The calibrated GFP measurements of residual stress patterns surrounding the damage sites are presented. Keywords: Glass, fused silica, photoelasticity, residual stress

  14. HVI Ballistic Limit Characterization of Fused Silica Thermal Panes

    NASA Technical Reports Server (NTRS)

    Miller, J. E.; Bohl, W. D.; Christiansen, E. L.; Davis, B. A.; Deighton, K. D.

    2015-01-01

    Fused silica window systems are used heavily on crewed reentry vehicles, and they are currently being used on the next generation of US crewed spacecraft, Orion. These systems improve crew situational awareness and comfort, as well as, insulating the reentry critical components of a spacecraft against the intense thermal environments of atmospheric reentry. Additionally, these materials are highly exposed to space environment hazards like solid particle impacts. This paper discusses impact studies up to 10 km/s on a fused silica window system proposed for the Orion spacecraft. A ballistic limit equation that describes the threshold of perforation of a fuse silica pane over a broad range of impact velocities, obliquities and projectile materials is discussed here.

  15. Enhanced characteristics of fused silica fibers using laser polishing

    NASA Astrophysics Data System (ADS)

    Heptonstall, A.; Barton, M. A.; Bell, A. S.; Bohn, A.; Cagnoli, G.; Cumming, A.; Grant, A.; Gustafson, E.; Hammond, G. D.; Hough, J.; Jones, R.; Kumar, R.; Lee, K.; Martin, I. W.; Robertson, N. A.; Rowan, S.; Strain, K. A.; Tokmakov, K. V.

    2014-05-01

    The search for gravitational wave signals from astrophysical sources has led to the current work to upgrade the two largest of the long-baseline laser interferometers, the LIGO detectors. The first fused silica mirror suspensions for the Advanced LIGO gravitational wave detectors have been installed at the LIGO Hanford and Livingston sites. These quadruple pendulums use synthetic fused silica fibers produced using a CO2 laser pulling machine to reduce thermal noise in the final suspension stage. The suspension thermal noise in Advanced LIGO is predicted to be limited by internal damping in the surface layer of the fibers, damping in the weld regions, and the strength of the fibers. We present here a new method for increasing the fracture strength of fused silica fibers by laser polishing of the stock material from which they are produced. We also show measurements of mechanical loss in laser polished fibers, showing a reduction of 30% in internal damping in the surface layer.

  16. Process for manufacturing hollow fused-silica insulator cylinder

    SciTech Connect

    Sampayan, Stephen E.; Krogh, Michael L.; Davis, Steven C.; Decker, Derek E.; Rosenblum, Ben Z.; Sanders, David M.; Elizondo-Decanini, Juan M.

    2001-01-01

    A method for building hollow insulator cylinders that can have each end closed off with a high voltage electrode to contain a vacuum. A series of fused-silica round flat plates are fabricated with a large central hole and equal inside and outside diameters. The thickness of each is related to the electron orbit diameter of electrons that escape the material surface, loop, and return back. Electrons in such electron orbits can support avalanche mechanisms that result in surface flashover. For example, the thickness of each of the fused-silica round flat plates is about 0.5 millimeter. In general, the thinner the better. Metal, such as gold, is deposited onto each top and bottom surface of the fused-silica round flat plates using chemical vapor deposition (CVD). Eutectic metals can also be used with one alloy constituent on the top and the other on the bottom. The CVD, or a separate diffusion step, can be used to defuse the deposited metal deep into each fused-silica round flat plate. The conductive layer may also be applied by ion implantation or gas diffusion into the surface. The resulting structure may then be fused together into an insulator stack. The coated plates are aligned and then stacked, head-to-toe. Such stack is heated and pressed together enough to cause the metal interfaces to fuse, e.g., by welding, brazing or eutectic bonding. Such fusing is preferably complete enough to maintain a vacuum within the inner core of the assembled structure. A hollow cylinder structure results that can be used as a core liner in a dielectric wall accelerator and as a vacuum envelope for a vacuum tube device where the voltage gradients exceed 150 kV/cm.

  17. Quantification of residual stress from photonic signatures of fused silica

    SciTech Connect

    Cramer, K. Elliott; Yost, William T.; Hayward, Maurice

    2014-02-18

    A commercially available grey-field polariscope (GFP) instrument for photoelastic examination is used to assess impact damage inflicted upon the outer-most pane of Space Shuttle windows made from fused silica. A method and apparatus for calibration of the stress-optic coefficient using four-point bending is discussed. The results are validated on known material (acrylic) and are found to agree with literature values to within 6%. The calibration procedure is then applied to fused-silica specimens and the stress-optic coefficient is determined to be 2.43 ± 0.54 × 10{sup −12} Pa{sup −1}. Fused silica specimens containing impacts artificially made at NASA’s Hypervelocity Impact Technology Facility (HIT-F), to simulate damage typical during space flight, are examined. The damage sites are cored from fused silica window carcasses and examined with the GFP. The calibrated GFP measurements of residual stress patterns surrounding the damage sites are presented.

  18. Fused silica mirror development for SIRTF

    NASA Technical Reports Server (NTRS)

    Barnes, W. P., Jr.

    1983-01-01

    An advanced design, lightweight, fuse-quartz mirror of sandwich construction was evaluated for optical figure performance at cryogenic temperatures. A low temperature shroud was constructed with an integral mirror mount and interface to a cryostat for use in a vacuum chamber. The mirror was tested to 13 K. Cryogenic distortion of the mirror was measured interferometrically. Separate interferometry of the chamber window during the test permitted subtraction of the small window distortions from the data. Results indicate that the imaging performance of helium cooled, infrared telescopes will be improved using this type of mirror without correction of cryogenic distortion of the primary mirror.

  19. Ultrafast laser-induced birefringence in various porosity silica glasses: from fused silica to aerogel.

    PubMed

    Cerkauskaite, Ausra; Drevinskas, Rokas; Rybaltovskii, Alexey O; Kazansky, Peter G

    2017-04-03

    We compare a femtosecond laser induced modification in silica matrices with three different degrees of porosity. In single pulse regime, the decrease of substrate density from fused silica to high-silica porous glass and to silica aerogel glass results in tenfold increase of laser affected region with the formation of a symmetric cavity surrounded by the compressed silica shell with pearl like structures. In multi-pulse regime, if the cavity produced by the first pulse is relatively large, the subsequent pulses do not cause further modifications. If not, the transition from void to the anisotropic structure with the optical axis oriented parallel to the incident polarization is observed. The maximum retardance value achieved in porous glass is twofold higher than in fused silica, and tenfold greater than in aerogel. The polarization sensitive structuring in porous glass by two pulses of ultrafast laser irradiation is demonstrated, as well as no observable stress is generated at any conditions.

  20. Fluorescence imaging of the desorption of dye from fused silica versus silica gel.

    PubMed

    Ludes, Melody D; Anthony, Shyroine R; Wirth, Mary J

    2003-07-01

    The desorption rate constants for a cationic dye from strong adsorption sites are compared for the same chromatographic interface but for two different substrates, fused silica and chromatographic silica gel. The dye is 1,1'-didodecyl-3,3,3'3'-tetramethylindocarbocyanine perchlorate (DiI). The interface consists of acetonitrile and a hydrocarbon monolayer (C8) covalently bound to the silica substrate. To measure slow desorption from fused silica, fluorescence imaging combined with correlation spectroscopy is used. To measure slow desorption from silica gel, fluorescence movies of silica gel particles are used. In both cases, the results show that there are two types of slow desorption processes on time scales exceeding 1 s. The desorption time from one type of site is within an experimental error of 7 s for both silica substrates. The adsorption kinetics for this type of site are slow, and the equilibrium population of DiI on these sites is comparable to that for DiI weakly adsorbed to the hydrocarbon monolayer. For the second type of site, for fused silica, the population of DiI is even higher than that of weakly adsorbed DiI, and the desorption time constant is approximately 2 min, although this is likely shortened by photobleaching. For silica gel, the relative population of DiI on this ultrastrong site is more than an order of magnitude lower, and the desorption time constant is 4.0 +/- 0.1 min. Both silica substrates thus show two types of sites whose time constants agree within experimental error, suggesting that the strong adsorption sites on fused silica are chemically the same as those on chromatographic silica gel.

  1. HVI Ballistic Limit Charaterization of Fused Silica Thermal Pane

    NASA Technical Reports Server (NTRS)

    Bohl, William E.; Miller, Joshua E.; Christiansen, Eric L.; Deighton, Kevin.; Davis, Bruce

    2015-01-01

    The Orion spacecraft's windows are exposed to the micrometeroid and orbital debris (MMOD) space environments while in space as well as the Earth entry environment at the mission's conclusion. The need for a low-mass spacecraft window design drives the need to reduce conservatism when assessing the design for loss of crew due to MMOD impact and subsequent Earth entry. Therefore, work is underway at NASA and Lockheed Martin to improve characterization of the complete penetration ballistic limit of an outer fused silica thermal pane. Hypervelocity impact tests of the window configuration at up to 10 km/s and hydrocode modeling have been performed with a variety of projectile materials to enable refinement of the fused silica ballistic limit equation.

  2. Mechanical protection of DLC films on fused silica slides

    NASA Technical Reports Server (NTRS)

    Nir, D.

    1985-01-01

    Measurements were made with a new test for improved quantitative estimation of the mechanical protection of thin films on optical materials. The mechanical damage was induced by a sand blasting system using spherical glass beads. Development of the surface damage was measured by the changes in the specular transmission and reflection, and by inspection using a surface profilometer and a scanning electron microscope. The changes in the transmittance versus the duration of sand blasting was measured for uncoated fused silica slides and coated ones. It was determined that the diamond like carbon films double the useful optical lifetime of the fused silica. Theoretical expressions were developed to describe the stages in surface deterioration. Conclusions were obtained for the SiO2 surface mechanism and for the film removal mechanism.

  3. Monolithic Cylindrical Fused Silica Resonators with High Q Factors

    PubMed Central

    Pan, Yao; Wang, Dongya; Wang, Yanyan; Liu, Jianping; Wu, Suyong; Qu, Tianliang; Yang, Kaiyong; Luo, Hui

    2016-01-01

    The cylindrical resonator gyroscope (CRG) is a typical Coriolis vibratory gyroscope whose performance is determined by the Q factor and frequency mismatch of the cylindrical resonator. Enhancing the Q factor is crucial for improving the rate sensitivity and noise performance of the CRG. In this paper, for the first time, a monolithic cylindrical fused silica resonator with a Q factor approaching 8 × 105 (ring-down time over 1 min) is reported. The resonator is made of fused silica with low internal friction and high isotropy, with a diameter of 25 mm and a center frequency of 3974.35 Hz. The structure of the resonator is first briefly introduced, and then the experimental non-contact characterization method is presented. In addition, the post-fabrication experimental procedure of Q factor improvement, including chemical and thermal treatment, is demonstrated. The Q factor improvement by both treatments is compared and the primary loss mechanism is analyzed. To the best of our knowledge, the work presented in this paper represents the highest reported Q factor for a cylindrical resonator. The proposed monolithic cylindrical fused silica resonator may enable high performance inertial sensing with standard manufacturing process and simple post-fabrication treatment. PMID:27483263

  4. High strength fused silica flexures manufactured by femtosecond laser

    NASA Astrophysics Data System (ADS)

    Bellouard, Yves; Said, Ali A.; Dugan, Mark; Bado, Philippe

    2009-02-01

    Flexures are mechanical elements used in micro- and precision-engineering to precisely guide the motion of micro-parts. They consist of slender bodies that deform elastically upon the application of a force. Although counter-intuitive at first, fused silica is an attractive material for flexure. Pending that the machining process does not introduce surface flaws that would lead to catastrophic failure, the material has a theoretically high ultimate tensile strength of several GPa. We report on high-aspect ratio fused silica flexures manufactured by femtosecond laser combined with chemical etching. Notch-hinges with thickness as small as twenty microns and aspect ratios comparable to aspect ratios obtained by Deep- Reactive-Ion-Etching (DRIE) were fabricated and tested under different loading conditions. Multiple fracture tests were performed for various loading conditions and the cracks morphologies were analyzed using Scanning Electron Microscopy. The manufactured elements show outstanding mechanical properties with flexural strengths largely exceeding those obtained with other technologies and materials. Fused silica flexures offer a mean to combine integrated optics with micro-mechanics in a single monolithic substrate. Waveguides and mechanical elements can be combined in a monolithic devices opening new opportunities for integrated opto-mechatronics devices.

  5. The mechanism of growth of quartz crystals into fused silica

    NASA Technical Reports Server (NTRS)

    Fratello, V. J.; Hays, J. F.; Spaepen, F.; Turnbull, D.

    1980-01-01

    It is proposed that the growth of quartz crystals into fused silica is effected by a mechanism involving the breaking of an Si-O bond and its association with an OH group, followed by cooperative motion of the nonbridging oxygen and the hydroxyl group which results in the crystallization of a row of several molecules along a crystalline-amorphous interfacial ledge. This mechanism explains, at least qualitatively, all the results of the earlier experimental study of the dependence of quartz crystal growth upon applied pressure: large negative activation volume; single activation enthalpy below Si-O bond energy; growth velocity constant in time, proportional to the hydroxyl and chlorine content, decreasing with increasing degree of reduction, and enhanced by nonhydrostatic stresses; lower pre-exponential for the synthetic than for the natural silica.

  6. Optimized condition for etching fused-silica phase gratings with inductively coupled plasma technology.

    PubMed

    Wang, Shunquan; Zhou, Changhe; Ru, Huayi; Zhang, Yanyan

    2005-07-20

    Polymer deposition is a serious problem associated with the etching of fused silica by use of inductively coupled plasma (ICP) technology, and it usually prevents further etching. We report an optimized etching condition under which no polymer deposition will occur for etching fused silica with ICP technology. Under the optimized etching condition, surfaces of the fabricated fused silica gratings are smooth and clean. Etch rate of fused silica is relatively high, and it demonstrates a linear relation between etched depth and working time. Results of the diffraction of gratings fabricated under the optimized etching condition match theoretical results well.

  7. Ultrafast double-pulse ablation of fused silica

    SciTech Connect

    Chowdhury, Ihtesham H.; Xu Xianfan; Weiner, Andrew M.

    2005-04-11

    Ultrafast pump-probe experiments were used to study high-intensity ultrafast pulse-ablation dynamics in fused silica. Two laser pulses with varied time delay and pulse energy were used to irradiate fused silica samples and observe the transient reflectivity and transmissivity of the probe pulse. It was seen that the probe reflectivity initially increased due to the formation of free-electron plasma and then dropped to a low value within a period of about 10 ps caused by a rapid structural change at the surface. The time-resolved measurements of reflectivity and transmissivity were also related to atomic force microscopy measurements of the depth of the laser-ablated hole. It was seen that the depth peaked at zero delay between the pulses and decreased within a period of about 1 ps as the temporal separation between the pulses was increased caused by the screening by the plasma produced by the first pulse. When the temporal separation is about 100 ps or longer, evidence for melting and resolidification during double-pulse ablation was also observed in the form of ridges at the circumference of the ablated holes.

  8. Laser induced damage and fracture in fused silica vacuum windows

    SciTech Connect

    Campbell, J.H.; Hurst, P.A.; Heggins, D.D.; Steele, W.A.; Bumpas, S.E.

    1996-11-01

    Laser-induced damage, that initiates catastrophic fracture, has been observed in large ({le}61 cm dia) fused silica lenses that also serve as vacuum barriers in Nova and Beamlet lasers. If the elastic stored energy in the lens is high enough, the lens will fracture into many pieces (implosion). Three parameters control the degree of fracture in the vacuum barrier window: elastic stored energy (tensile stress), ratio of window thickness to flaw depth, and secondary crack propagation. Fracture experiments were conducted on 15-cm dia fused silica windows that contain surface flaws caused by laser damage. Results, combined with window failure data on Beamlet and Nova, were used to develop design criteria for a ``fail-safe`` lens (that may catastrophically fracture but not implode). Specifically, the window must be made thick enough so that the peak tensile stress is less than 500 psi (3.4 MPa) and the thickness/critical flaw size is less than 6. The air leak through the window fracture and into the vacuum must be rapid enough to reduce the load on the window before secondary crack growth occurs. Finite element stress calculations of a window before and immediately following fracture into two pieces show that the elastic stored energy is redistributed if the fragments ``lock`` in place and thereby bridge the opening. In such cases, the peak stresses at the flaw site can increase, leading to further (i.e. secondary) crack growth.

  9. Thermal annealing of laser damage precursors on fused silica surfaces

    SciTech Connect

    Shen, N; Miller, P E; Bude, J D; Laurence, T A; Suratwala, T I; Steele, W A; Feit, M D; Wang, L L

    2012-03-19

    Previous studies have identified two significant precursors of laser damage on fused silica surfaces at fluenes below {approx} 35 J/cm{sup 2}, photoactive impurities in the polishing layer and surface fractures. In the present work, isothermal heating is studied as a means of remediating the highly absorptive, defect structure associated with surface fractures. A series of Vickers indentations were applied to silica surfaces at loads between 0.5N and 10N creating fracture networks between {approx} 10{micro}m and {approx} 50{micro}m in diameter. The indentations were characterized prior to and following thermal annealing under various times and temperature conditions using confocal time-resolved photo-luminescence (CTP) imaging, and R/1 optical damage testing with 3ns, 355nm laser pulses. Significant improvements in the damage thresholds, together with corresponding reductions in CTP intensity, were observed at temperatures well below the glass transition temperature (T{sub g}). For example, the damage threshold on 05.N indentations which typically initiates at fluences <8 J/cm{sup 2} could be improved >35 J/cm{sup 2} through the use of a {approx} 750 C thermal treatment. Larger fracture networks required longer or higher temperature treatment to achieve similar results. At an annealing temperature > 1100 C, optical microscopy indicates morphological changes in some of the fracture structure of indentations, although remnants of the original fracture and significant deformation was still observed after thermal annealing. This study demonstrates the potential of using isothermal annealing as a means of improving the laser damage resistance of fused silica optical components. Similarly, it provides a means of further understanding the physics associated with optical damage and related mitigation processes.

  10. High-power laser damage in fused silica

    NASA Astrophysics Data System (ADS)

    Salleo, Alberto

    Laser-induced damage (LID) at the surface of transparent materials is widely considered the main obstacle in the development of inertial confinement fusion (ICF) facilities. This dissertation is a study, both theoretical and experimental, of LID initiation and propagation at fused silica surfaces. Numerical simulation of light propagation shows that micro-cracks due to polishing amplify light intensity in their vicinity at the air/glass boundary. The mechanism of light amplification is a combination of partial reflection at air/glass boundaries and constructive interference of the reflected waves. The maximum amplification factor for a single crack is 10.7. Multiple cracks interact cooperatively and generate higher amplification factors. Conical cracks generate amplification factors of 20. The electric field intensity profile at the glass surface due to underlying conical cracks correlates well with observed LID morphology. Light amplification at micro-cracks may also play a role in LID propagation. LID propagation rates under repetitive illumination are measured. Rear-surface LID propagates from pre-existing damage sites at sub-threshold fluence. Rear-surface propagation rates depend linearly on laser fluence and are independent of environment or beam size. Rear-surface LID propagates faster in the UV than in the IR. Front-surface LID propagation is two orders of magnitude slower than rear-surface propagation. Pump and probe experiments of LID confirm that this difference is due to laser-plasma interactions. At the front-surface, up to 60% of the laser energy is dispersed outside the glass. At the rear-surface, 35% of the laser energy is dispersed outside the glass, thus more energy is available for damage propagation. Based on these observations, a model of LID propagation is developed based on the physics of impact cratering. Laser-induced transformations of glass are studied. High pressures associated with LID permanently densify fused silica by as much as 20

  11. Characterization of the polishing induced contamination of fused silica optics

    NASA Astrophysics Data System (ADS)

    Pfiffer, Mathilde; Longuet, Jean-Louis; Labrugère, Christine; Fargin, Evelyne; Bousquet, Bruno; Dussauze, Marc; Lambert, Sébastien; Cormont, Philippe; Néauport, Jérôme

    2016-12-01

    Secondary Ion Mass Spectroscopy (SIMS), Electron Probe Micro Analysis (EPMA) and X-Ray Photoelectron Spectroscopy (XPS) were used to analyze the polishing induced contamination layer at the fused silica optics surface. Samples were prepared using an MRF polishing machine and cerium-based slurry. The cerium and iron penetration and concentration were measured in the surface out of defects. Cerium is embedded at the surface in a 60 nm layer and concentrated at 1200 ppmw in this layer while iron concentration falls down at 30 nm. Spatial distribution and homogeneity of the pollution were also studied in scratches and bevel using SIMS and EPMA techniques. An overconcentration was observed in the chamfer and we saw evidence that surface defects such as scratches are specific places that hold the pollutants. A wet etching was able to completely remove the contamination in the scratch.

  12. Fabrication of microchannels in fused silica using femtosecond Bessel beams

    SciTech Connect

    Yashunin, D. A.; Malkov, Yu. A.; Mochalov, L. A.; Stepanov, A. N.

    2015-09-07

    Extended birefringent waveguiding microchannels up to 15 mm long were created inside fused silica by single-pulse irradiation with femtosecond Bessel beams. The birefringent refractive index change of 2–4 × 10{sup −4} is attributed to residual mechanical stress. The microchannels were chemically etched in KOH solution to produce 15 mm long microcapillaries with smooth walls and a high aspect ratio of 1:250. Bessel beams provide higher speed of material processing compared to conventional multipulse femtosecond laser micromachining techniques and permit simple control of the optical axis direction of the birefringent waveguides, which is important for practical applications [Corrielli et al., “Rotated waveplates in integrated waveguide optics,” Nat. Commun. 5, 4249 (2014)].

  13. Optical Properties of the DIRC Fused Silica Radiator

    SciTech Connect

    Convery, Mark R

    2003-04-15

    The DIRC detector is successfully operating as the hadronic particle identification system for the BaBar experiment at SLAC. The production of its Cherenkov radiator required much effort in practice, both in manufacture and conception, which in turn required a large number of R&D measurements. One of the major outcomes of this R&D work was an understanding of methods to select radiation hard and optically uniform fused silica material. Others included measurement of the wavelength dependency of the internal reflection coefficient, and its sensitivity to the surface pollution, selection of the radiator support, selection of good optical glue, etc. This note summarizes the optical R&D test results.

  14. Discharging fused silica optics occluded by an electrostatic drive

    NASA Astrophysics Data System (ADS)

    Ugolini, D.; Fitzgerald, C.; Rothbarth, I.; Wang, J.

    2014-03-01

    Charge accumulation on test masses is a potentially limiting noise source for gravitational-wave interferometers, and may occur due to exposure to an electrostatic drive (ESD) in modern test mass suspensions. We verify that an ESD can cause charge accumulation on a fused silica test mass at a rate of 8 × 10-16 C/cm2/h. We also demonstrate a charge mitigation system consisting of a stream of nitrogen ionized by copper feedthrough pins at 3750 VAC. We demonstrate that the system can neutralize positive and negative charge from 10-11 C/cm2 to 3 × 10-14 C/cm2 in under 2 h.

  15. Note: Discharging fused silica test masses with ionized nitrogen

    NASA Astrophysics Data System (ADS)

    Ugolini, D.; Funk, Q.; Amen, T.

    2011-04-01

    We have developed a technique for discharging fused silica test masses in a gravitational-wave interferometer with nitrogen ionized by an electron beam. The electrons are produced from a heated filament by thermionic emission in a low-pressure region to avoid contamination and burnout. Some electrons then pass through a small aperture and ionize nitrogen in a higher-pressure region, and this ionized gas is pumped across the test mass surface, neutralizing both polarities of charge. The discharge rate varies exponentially with charge density and filament current, quadratically with filament potential, and has an optimal working pressure of ˜8 mT. Adapting the technique to larger test mass chambers is also discussed.

  16. Modification of nanostructured fused silica for use as superhydrophobic, IR-transmissive, anti-reflective surfaces

    NASA Astrophysics Data System (ADS)

    Boyd, Darryl A.; Frantz, Jesse A.; Bayya, Shyam S.; Busse, Lynda E.; Kim, Woohong; Aggarwal, Ishwar; Poutous, Menelaos; Sanghera, Jasbinder S.

    2016-04-01

    In order to mimic and enhance the properties of moth eye-like materials, nanopatterned fused silica was chemically modified to produce self-cleaning substrates that have anti-reflective and infrared transmissive properties. The characteristics of these substrates were evaluated before and after chemical modification. Furthermore, their properties were compared to fused silica that was devoid of surface features. The chemical modification imparted superhydrophobic character to the substrates, as demonstrated by the average water contact angles which exceeded 170°. Finally, optical analysis of the substrates revealed that the infrared transmission capabilities of the fused silica substrates (nanopatterned to have moth eye on one side) were superior to those of the regular fused silica substrates within the visible and near-infrared region of the light spectrum, with transmission values of 95% versus 92%, respectively. The superior transmission properties of the fused silica moth eye were virtually unchanged following chemical modification.

  17. Fabrication of concave microlens arrays by local fictive temperature modification of fused silica.

    PubMed

    Zhang, Chuanchao; Liao, Wei; Yang, Ke; Liu, Taixiang; Bai, Yang; Zhang, Lijuan; Jiang, Xiaolong; Chen, Jing; Jiang, Yilan; Wang, Haijun; Luan, Xiaoyu; Zhou, Hai; Yuan, Xiaodong; Zheng, Wanguo

    2017-03-15

    A simple and convenient means of fabricating concave microlens arrays direct on silica glass by using the local fictive temperature modification of fused silica is presented. This method is based on the fact that an increased fictive temperature results in a much higher HF acid etching rate of fused silica. Combining the abrupt local fictive temperature enhancement by the CO2 laser pulse and the subsequent etching by the HF acid solution, concave microlens arrays with high fill factors, excellent smoothness, and optical performance are generated on fused silica.

  18. Defect study in fused silica using near field scanning optical microscopy

    SciTech Connect

    Yan, M.; Wang, L.; Siekhaus, W.; Kozlowski, M.; Yang, J.; Mohideen, U.

    1998-01-21

    Surface defects in fused silica have been characterized using Near Field Scanning Optical Microscopy (NSOM). Using total internal reflection of a p- or s- polarized laser beam, optical scattering from defects located on the surface itself as well as in the subsurface layer of polished fused silica has been measured by NSOM. The local scattering intensity has been compared with simultaneously measured surface topography. In addition, surface defects intentionally created on a fused silica surface by nano-indentation have been used to establish a correlation between optical scattering of s- and p- polarized light, surface morphology and the well known subsurface stress-field associated with nano-indentation.

  19. UV Laser Conditioning for Reduction of 351-nm Damage Initiation in Fused Silica

    SciTech Connect

    Brusasco, R M; Penetrante, B M; Peterson, J E; Maricle, S M; Menapace, J A

    2001-12-20

    This paper describes the effect of 355-nm laser conditioning on the concentration of UV-laser-induced surface damage sites on large-aperture fused silica optics. We will show the effect of various 355-nm laser conditioning methodologies on the reduction of surface-damage initiation in fused silica samples that have varying qualities of polishing. With the best, generally available fused silica optic, we have demonstrated that 355-nm laser conditioning can achieve up to 10x reduction in surface damage initiation concentration in the fluence range of 10-14 J/cm{sup 2} (355-nm {at} 3 ns).

  20. Indirect slumping of D263 glass on Fused Silica mould

    NASA Astrophysics Data System (ADS)

    Proserpio, Laura; Wen, Mingwu; Breunig, Elias; Burwitz, Vadim; Friedrich, Peter; Madarasz, Emanuel

    2016-07-01

    The Slumped Glass Optic (SGO) group of the Max Planck Institute for Extraterrestrial physics (MPE) is studying the indirect slumping technology for its application to X-ray telescope manufacturing. Several aspects of the technology have been analyzed in the past. During the last months, we concentrated our activities on the slumping of Schott D263 glass on a precise machined Fused Silica mould: The concave mould was produced by the Italian company Media Lario Technologies with the parabola and hyperbola side of the typical Wolter I design in one single piece. Its shape quality was estimated by optical metrology to be around 6 arcsec Half Energy Width (HEW) in double reflection. The application of an anti-sticking Boron Nitride layer was necessary to avoid the adhesion of the glass on the mould during the forming process at high temperatures. The mould has been used for the slumping of seven mirror segments 200 mm long, 100 mm wide, and with thickness of 200 μm or 400 μm. The influence of the holding time at maximum temperature was explored in this first run of tests. The current results of the activities are described in the paper and plans for further investigations are outlined.

  1. Density variation in fused silica exposed to femtosecond laser

    NASA Astrophysics Data System (ADS)

    Champion, Audrey; Bellouard, Yves

    2012-01-01

    Fused silica (a-SiO2) exposure to low-energy femtosecond laser pulses leads to interesting effects such as a local increase of etching rate and/or a local increase of refractive index. Up to now the exact modifications occurring in the glass matrix after exposure remains elusive and various hypotheses among which the formation of color centers or of densified zones have been proposed. In the densification model, shorter SiO2 rings form in the glass matrix leading to an enhanced etching rate. In this paper, we investigate quantitatively the amount of volume variation occurring in well-defined laser exposed areas. Our method is based on the deflection of glass cantilevers and hypotheses from classical beam theory. Specifically, 20-mm long cantilevers are fabricated using low-energy femtosecond laser pulses. After chemical etching, the cantilevers are exposed a second time to the same femtosecond laser but only in their upper-half thickness and this time, without a subsequent etching step. We observe micron-scale displacements at the cantilever tips that we use to estimate the volume variation in laser affected zones. Our results not only show that in the regime where nanogratings form (so called type II structures), laser affected zones expand but also provide a quantitative method to estimate the amount of stress as a function of the laser exposure parameters.

  2. Time-resolved shadowgraphy of optical breakdown in fused silica

    NASA Astrophysics Data System (ADS)

    Tran, K. A.; Grigorov, Y. V.; Nguyen, V. H.; Rehman, Z. U.; Le, N. T.; Janulewicz, K. A.

    2015-07-01

    Dynamics of a laser-induced optical breakdown in the bulk of fused silica initiated by a sub-nanosecond laser pulse of an energy fluence as high as 8.7 kJ/cm2 was investigated by using femtosecond time-resolved shadowgraphy. Plasma ignition, growth of the damaged region and accompanying hydrodynamic motion were recorded from the moment directly before the arrival of the driving laser pulse, in the time steps adapted to the rate of the occurring processes. The growth rate of the plasma channel, curvature radii and velocities of the wave fronts were extracted from the shadowgrams. It was found that the plasma channel develops with a supersonic velocity and the first observed shock front tends to transform itself from the initial bowl-like shape to the final spherical one characterising an acoustic wave. Appearance of multiple fronts accompanying the main shock front was registered and used in more detailed analysis of the optical breakdown dynamics in the transparent dielectrics.

  3. High strain rate fracture behaviour of fused silica

    NASA Astrophysics Data System (ADS)

    Ruggiero, A.; Iannitti, G.; Testa, G.; Limido, J.; Lacome, J. L.; Olovsson, L.; Ferraro, M.; Bonora, N.

    2014-05-01

    Fused silica is a high purity synthetic amorphous silicon dioxide characterized by low thermal expansion coefficient, excellent optical qualities and exceptional transmittance over a wide spectral range. Because of its wide use in the military industry as window material, it may be subjected to high-energy ballistic impacts. Under such dynamic conditions, post-yield response of the ceramic as well as the strain rate related effects become significant and should be accounted for in the constitutive modelling. In this study, the Johnson-Holmquist (J-H) model parameters have been identified by inverse calibration technique, on selected validation test configurations, according to the procedure described hereafter. Numerical simulations were performed with LS-DYNA and IMPETUS-FEA, a general non-linear finite element software which offers NURBS finite element technology for the simulation of large deformation and fracture in materials. In order to overcome numerical drawbacks associated with element erosion, a modified version of the J-H model is proposed.

  4. Accelerated life time testing of fused silica for DUV laser applications revised

    NASA Astrophysics Data System (ADS)

    Mühlig, Christian; Bublitz, Simon

    2013-11-01

    We report on the continuation of a comparative study of different fused silica materials for ArF laser applications. After selecting potentially suited fused silica materials from their laser induced absorption and compaction obtained by a short time testing procedure, accelerated life time tests have been undertaken by sample irradiating at liquid nitrogen temperature and subsequent direct absorption measurements using the laser induced deflection (LID) technique. The obtained degradation acceleration strongly differs between fused silica materials showing high and low OH contents, respectively. As a result, a difference in the absorption degradation mechanism between high and low OH containing fused silica is proposed. Consequently two different scenarios for an acceleration of the absorption degradation are derived.

  5. Shock-wave equation-of-state measurements in fused silica up to 1600 GPa

    DOE PAGES

    McCoy, C. A.; Gregor, M. C.; Polsin, D. N.; ...

    2016-06-02

    The properties of silica are important to geophysical and high-pressure equation of state research. The most prevalent crystalline form, α-quartz, has been extensively studied to TPa pressures. Recent experiments with amorphous silica, commonly referred to as fused silica, provided Hugoniot and reflectivity data up to 630 GPa using magnetically-driven aluminum impactors. This article presents measurements of the fused silica Hugoniot over the range from 200 to 1600 GPa using laser-driven shocks with a quartz standard. These results extend the measured Hugoniot of fused silica to higher pressures, but more importantly, in the 200-600 GPa range, the data are very goodmore » agreement with those obtained with a different driver and standard material. As a result, a new shock velocity-particle velocity relation is derived to fit the experimental data.« less

  6. Shock-wave equation-of-state measurements in fused silica up to 1600 GPa

    SciTech Connect

    McCoy, C. A.; Gregor, M. C.; Polsin, D. N.; Fratanduono, D. E.; Celliers, P. M.; Boehly, T. R.; Meyerhofer, D. D.

    2016-06-02

    The properties of silica are important to geophysical and high-pressure equation of state research. The most prevalent crystalline form, α-quartz, has been extensively studied to TPa pressures. Recent experiments with amorphous silica, commonly referred to as fused silica, provided Hugoniot and reflectivity data up to 630 GPa using magnetically-driven aluminum impactors. This article presents measurements of the fused silica Hugoniot over the range from 200 to 1600 GPa using laser-driven shocks with a quartz standard. These results extend the measured Hugoniot of fused silica to higher pressures, but more importantly, in the 200-600 GPa range, the data are very good agreement with those obtained with a different driver and standard material. As a result, a new shock velocity-particle velocity relation is derived to fit the experimental data.

  7. Subsurface defects of fused silica optics and laser induced damage at 351 nm.

    PubMed

    Hongjie, Liu; Jin, Huang; Fengrui, Wang; Xinda, Zhou; Xin, Ye; Xiaoyan, Zhou; Laixi, Sun; Xiaodong, Jiang; Zhan, Sui; Wanguo, Zheng

    2013-05-20

    Many kinds of subsurface defects are always present together in the subsurface of fused silica optics. It is imperfect that only one kind of defects is isolated to investigate its impact on laser damage. Therefore it is necessary to investigate the impact of subsurface defects on laser induced damage of fused silica optics with a comprehensive vision. In this work, we choose the fused silica samples manufactured by different vendors to characterize subsurface defects and measure laser induced damage. Contamination defects, subsurface damage (SSD), optical-thermal absorption and hardness of fused silica surface are characterized with time-of-flight secondary ion mass spectrometry (TOF-SIMS), fluorescence microscopy, photo-thermal common-path interferometer and fully automatic micro-hardness tester respectively. Laser induced damage threshold and damage density are measured by 351 nm nanosecond pulse laser. The correlations existing between defects and laser induced damage are analyzed. The results show that Cerium element and SSD both have a good correlation with laser-induced damage thresholds and damage density. Research results evaluate process technology of fused silica optics in China at present. Furthermore, the results can provide technique support for improving laser induced damage performance of fused silica.

  8. Effect of Sintering Temperature on the Properties of Fused Silica Ceramics Prepared by Gelcasting

    NASA Astrophysics Data System (ADS)

    Wan, Wei; Huang, Chun-e.; Yang, Jian; Zeng, Jinzhen; Qiu, Tai

    2014-07-01

    Fused silica ceramics were fabricated by gelcasting, by use of a low-toxicity N' N-dimethylacrylamide gel system, and had excellent properties compared with those obtained by use of the low-toxicity 2-hydroxyethyl methacrylate and toxic acrylamide systems. The effect of sintering temperature on the microstructure, mechanical and dielectric properties, and thermal shock resistance of the fused silica ceramics was investigated. The results showed that sintering temperature has a critical effect. Use of an appropriate sintering temperature will promote densification and improve the strength, thermal shock resistance, and dielectric properties of fused silica ceramics. However, excessively high sintering temperature will greatly facilitate crystallization of amorphous silica and result in more cristobalite in the sample, which will cause deterioration of these properties. Fused silica ceramics sintered at 1275°C have the maximum flexural strength, as high as 81.32 MPa, but, simultaneously, a high coefficient of linear expansion (2.56 × 10-6/K at 800°C) and dramatically reduced residual flexural strength after thermal shock (600°C). Fused silica ceramics sintered at 1250°C have excellent properties, relatively high and similar flexural strength before (67.43 MPa) and after thermal shock (65.45 MPa), a dielectric constant of 3.34, and the lowest dielectric loss of 1.20 × 10-3 (at 1 MHz).

  9. Metallic-like photoluminescence and absorption in fused silica surface flaws

    SciTech Connect

    Laurence, T A; Bude, J D; Shen, N; Feldman, T; Miller, P; Steele, W A; Suratwala, T

    2008-09-11

    Using high-sensitivity confocal time-resolved photoluminescence (PL) techniques, we report an ultra-fast PL (40ps-5ns) from impurity-free surface flaws on fused silica, including polished, indented or fractured surfaces of fused silica, and from laser-heated evaporation pits. This PL is excited by the single photon absorption of sub-band gap light, and is especially bright in fractures. Regions which exhibit this PL are strongly absorptive well below the band gap, as evidenced by a propensity to damage with 3.5eV ns-scale laser pulses.

  10. Laser-induced damage on fused silica with photo-acoustic method

    NASA Astrophysics Data System (ADS)

    Yi, Muyu; Ke, Kai; Zhao, Jianjun; Yuan, Xiao; Zhang, Xiang

    2016-11-01

    The surface damage processes of fused silica are studied by a new photo-acoustic probe with Anti-Emi (Electron-Magnetic Interference), easy-adjusted and non-damage for the samples, and the damage thresholds is detected according to the rapid increase of the acoustic signals. Experimental results show that the damage threshold of fused silica samples is 13.86 J/cm2 at the wavelength of 1064 nm and the pulse width of 10 ns. This work may provide an effective technical support for the laser-induced damage detection.

  11. Shock-wave equation-of-state measurements in fused silica up to 1600 GPa

    NASA Astrophysics Data System (ADS)

    McCoy, C. A.; Gregor, M. C.; Polsin, D. N.; Fratanduono, D. E.; Celliers, P. M.; Boehly, T. R.; Meyerhofer, D. D.

    2016-06-01

    The properties of silica are important to geophysical and high-pressure equation-of-state research. Its most-prevalent crystalline form, α-quartz, has been extensively studied to TPa pressures. This article presents Hugoniot measurements on amorphous silica, commonly referred to as fused silica, over a range from 200 to 1600 GPa using laser-driven shocks and an α-quartz standard. These results extend the measured Hugoniot of fused silica to higher pressures. In the 200- to 600-GPa range, the data are in very good agreement with those obtained by Qi et al. [Phys. Plasmas 22, 062706 (2015)] using magnetically driven aluminum impactors and aluminum as a standard material. A new shock velocity/particle velocity relation is derived to fit the experimental data.

  12. Yb/Al-codoped fused-silica planar-waveguide amplifier

    NASA Astrophysics Data System (ADS)

    Atar, Gil; Eger, David; Bruner, Ariel; Sfez, Bruno; Ruschin, Shlomo

    2016-05-01

    We report an Yb/Al-codoped fused silica planar waveguide amplifier with <0.2 dB/cm passive loss and 0.6 dB/cm gain, featuring a high damage threshold (>0.1 GW/cm2) and a relatively large core (20 μm thick). Waveguide fabrication is based on a novel silica-on-silica technology combining modified-chemical-vapor deposition and a high temperature CO2 laser treatment for making high-power photonic devices.

  13. Densification and Devitrification of Fused Silica Induced by Ballistic Impact: A Computational Investigation

    DTIC Science & Technology

    2015-03-25

    investigations (e.g., [2–14]) established that, under high-rate ( shockwave or ballistic) loading conditions, fused-silica targets can, at least in the vicinity...computational simulations of planar longitudinal shockwave interactions with polyurea, soda-lime glass and polyurea/glass interfaces,” Multidiscipline

  14. Wear and mechanical properties of nano-silica-fused whisker composites.

    PubMed

    Xu, H H K; Quinn, J B; Giuseppetti, A A

    2004-12-01

    Resin composites must be improved if they are to overcome the high failure rates in large stress-bearing posterior restorations. This study aimed to improve wear resistance via nano-silica-fused whiskers. It was hypothesized that nano-silica-fused whiskers would significantly improve composite mechanical properties and wear resistance. Nano-silicas were fused onto whiskers and incorporated into a resin at mass fractions of 0%-74%. Fracture toughness (mean +/- SD; n = 6) was 2.92 +/- 0.14 MPa.m(1/2) for whisker composite with 74% fillers, higher than 1.13 +/- 0.19 MPa.m(1/2) for a prosthetic control, and 0.95 +/- 0.11 MPa.m(1/2) for an inlay/onlay control (Tukey's at 0.95). A whisker composite with 74% fillers had a wear depth of 77.7 +/- 6.9 mum, less than 118.0 +/- 23.8 microm of an inlay/onlay control, and 172.5 +/- 15.4 microm of a prosthetic control (p < 0.05). Linear correlations were established between wear and hardness, modulus, strength, and toughness, with R = 0.95-0.97. Novel nano-silica-fused whisker composites possessed high toughness and wear resistance with smooth worn surfaces, and may be useful in large stress-bearing restorations.

  15. Rapidly removing grinding damage layer on fused silica by inductively coupled plasma processing

    NASA Astrophysics Data System (ADS)

    Chen, Heng; Zhou, Lin; Xie, Xuhui; Shi, Baolu; Xiong, Haobin

    2016-10-01

    During the conventional optical shaping process of fused silica, lapping is generally used to remove grinding damage layer. But this process is of low efficiency, it cannot meet the demand of large aperture optical components. Therefore, Inductively Coupled Plasma Processing (ICPP) was proposed to remove grinding damage layer instead of lapping. ICPP is a non-contact, deterministic figuring technology performed at atmospheric pressure. The process benefits from its ability to simultaneously remove sub-surface damage (SSD) while imparting the desired figure to the surface with high material remove rate. The removing damage capability of ICPP has preliminarily been confirmed on medium size optical surfaces made of fused silica, meanwhile serious edge warping was found. This paper focused on edge effect and a technique has been designed to compensate for these difficulties. Then it was demonstrated on a large aperture fused silica mirror (Long320mm×Wide370mm×High50mm), the removal depth was 30.2μm and removal rate got 6.6mm3/min. The results indicate that ICPP can rapidly remove damage layer on the fused silica induced by the previous grinding process and edge effect is effective controlled.

  16. Femtosecond laser ablation dynamics of fused silica extracted from oscillation of time-resolved reflectivity

    SciTech Connect

    Kumada, Takayuki Akagi, Hiroshi; Itakura, Ryuji; Otobe, Tomohito; Yokoyama, Atsushi

    2014-03-14

    Femtosecond laser ablation dynamics of fused silica is examined via time-resolved reflectivity measurements. After optical breakdown was caused by irradiation of a pump pulse with fluence F{sub pump} = 3.3–14.9 J/cm{sup 2}, the reflectivity oscillated with a period of 63 ± 2 ps for a wavelength λ = 795 nm. The period was reduced by half for λ = 398 nm. We ascribe the oscillation to the interference between the probe pulses reflected from the front and rear surfaces of the photo-excited molten fused silica layer. The time-resolved reflectivity agrees closely with a model comprising a photo-excited layer which expands due to the formation of voids, and then separates into two parts, one of which is left on the sample surface and the other separated as a molten thin layer from the surface by the spallation mechanism. Such oscillations were not observed in the reflectivity of soda-lime glass. Whether the reflectivity oscillates or not probably depends on the layer viscosity while in a molten state. Since viscosity of the molten fused silica is several orders of magnitude higher than that of the soda-lime glass at the same temperature, fused silica forms a molten thin layer that reflects the probe pulse, whereas the soda-lime glass is fragmented into clusters.

  17. Goniometric and hemispherical reflectance and transmittance measurements of fused silica diffusers

    NASA Astrophysics Data System (ADS)

    Lemaillet, Paul; Patrick, Heather J.; Germer, Thomas A.; Hanssen, Leonard; Johnson, B. Carol; Georgiev, Georgi T.

    2016-09-01

    Fused silica diffusers, made by forming scattering centers inside fused silica glass, can exhibit desirable optical properties, such as reflectance or transmittance independent of viewing angle, spectrally flat response into the ultraviolet wavelength range, and good spatial uniformity. The diffusers are of interest for terrestrial and space borne remote sensing instruments, which use light diffusers in reflective and transmissive applications. In this work, we report exploratory measurements of two samples of fused silica diffusers. We will present goniometric bidirectional scattering distribution function (BSDF) measurements under normal illumination provided by the National Institute of Standards and Technology (NIST)'s Goniometric Optical Scatter Instrument (GOSI), by NIST's Infrared reference integrating sphere (IRIS) and by the National Aeronautics and Space Administration (NASA)'s Diffuser Calibration Laboratory. We also present hemispherical diffuse transmittance and reflectance measurements provided by NIST's Double integrating sphere Optical Scattering Instrument (DOSI). The data from the DOSI is analyzed by Prahl's inverse adding-doubling algorithm to obtain the absorption and reduced scattering coefficient of the samples. Implications of fused silica diffusers for remote sensing applications are discussed.

  18. Bulk damage and absorption in fused silica due to high-power laser applications

    NASA Astrophysics Data System (ADS)

    Nürnberg, F.; Kühn, B.; Langner, A.; Altwein, M.; Schötz, G.; Takke, R.; Thomas, S.; Vydra, J.

    2015-11-01

    Laser fusion projects are heading for IR optics with high broadband transmission, high shock and temperature resistance, long laser durability, and best purity. For this application, fused silica is an excellent choice. The energy density threshold on IR laser optics is mainly influenced by the purity and homogeneity of the fused silica. The absorption behavior regarding the hydroxyl content was studied for various synthetic fused silica grades. The main absorption influenced by OH vibrational excitation leads to different IR attenuations for OH-rich and low-OH fused silica. Industrial laser systems aim for the maximum energy extraction possible. Heraeus Quarzglas developed an Yb-doped fused silica fiber to support this growing market. But the performance of laser welding and cutting systems is fundamentally limited by beam quality and stability of focus. Since absorption in the optical components of optical systems has a detrimental effect on the laser focus shift, the beam energy loss and the resulting heating has to be minimized both in the bulk materials and at the coated surfaces. In collaboration with a laser research institute, an optical finisher and end users, photo thermal absorption measurements on coated samples of different fused silica grades were performed to investigate the influence of basic material properties on the absorption level. High purity, synthetic fused silica is as well the material of choice for optical components designed for DUV applications (wavelength range 160 nm - 260 nm). For higher light intensities, e.g. provided by Excimer lasers, UV photons may generate defect centers that effect the optical properties during usage, resulting in an aging of the optical components (UV radiation damage). Powerful Excimer lasers require optical materials that can withstand photon energy close to the band gap and the high intensity of the short pulse length. The UV transmission loss is restricted to the DUV wavelength range below 300 nm and

  19. Ionoluminescence of fused silica under swift ion irradiation

    NASA Astrophysics Data System (ADS)

    Saavedra, R.; Jiménez-Rey, D.; Martin, P.; Vila, R.

    2016-09-01

    Ion beam induced luminescence spectra have been in-situ recorded during He+ (2.5 MeV), O4+ (13.5 MeV) and Si4+ (24.4 MeV) irradiations for three vitreous silica grades with different OH content (KU1, KS-4V and Infrasil 301). Remarkable changes in the ionoluminescence spectra of the three silica grades were observed for low ion fluences. He+ irradiated samples exhibited higher luminescence than equivalent ones irradiated with heavier O4+ and Si4+ ions. KU1 samples with the highest OH content showed the lowest blue luminescence. Blue luminescence maximum during ion irradiations with O4+ and Si4+ ions is correlated with structural changes.

  20. Multi-Length Scale Analysis of the Effect of Fused-Silica Pre-shocking on its Tendency for Devitrification

    NASA Astrophysics Data System (ADS)

    Grujicic, M.; Snipes, J. S.; Ramaswami, S.

    2016-03-01

    Recent studies have suggested that impact-induced devitrification of fused silica, or more specifically formation of high-density stishovite, can significantly improve ballistic-penetration resistance of fused silica, the material which is used in transparent armor. The studies have also shown that in order for stishovite to form during a ballistic impact event, very high projectile kinetic energy normalized by the projectile/fused-silica target-plate contact area must accompany such an event. Otherwise fused-silica devitrification, if taking place, does not substantially improve the material ballistic-penetration resistance. In the present work, all-atom molecular-level computations are carried out in order to establish if pre-shocking of fused-silica target-plates (to form stishovite) and subsequent unloading (to revert stishovite to the material amorphous structure) can increase fused silica's propensity for stishovite formation during a ballistic impact. Towards that end, molecular-level computational procedures are developed to simulate both the pre-shocking treatment of the fused-silica target-plate and its subsequent impact by a solid right-circular cylindrical projectile. The results obtained clearly revealed that when strong-enough shockwaves are used in the fused-silica target-plate pre-shocking procedure, the propensity of fused silica for stishovite formation during the subsequent ballistic impact is increased, as is the associated ballistic-penetration resistance. To rationalize these findings, a detailed post-processing microstructural analysis of the pre-shocked material is employed. The results obtained suggest that fused silica pre-shocked with shockwaves of sufficient strength retain some memory/embryos of stishovite, and these embryos facilitate stishovite formation during the subsequent ballistic impact.

  1. Advanced Mitigation Process (AMP) for Improving Laser Damage Threshold of Fused Silica Optics

    NASA Astrophysics Data System (ADS)

    Ye, Xin; Huang, Jin; Liu, Hongjie; Geng, Feng; Sun, Laixi; Jiang, Xiaodong; Wu, Weidong; Qiao, Liang; Zu, Xiaotao; Zheng, Wanguo

    2016-08-01

    The laser damage precursors in subsurface of fused silica (e.g. photosensitive impurities, scratches and redeposited silica compounds) were mitigated by mineral acid leaching and HF etching with multi-frequency ultrasonic agitation, respectively. The comparison of scratches morphology after static etching and high-frequency ultrasonic agitation etching was devoted in our case. And comparison of laser induce damage resistance of scratched and non-scratched fused silica surfaces after HF etching with high-frequency ultrasonic agitation were also investigated in this study. The global laser induce damage resistance was increased significantly after the laser damage precursors were mitigated in this case. The redeposition of reaction produce was avoided by involving multi-frequency ultrasonic and chemical leaching process. These methods made the increase of laser damage threshold more stable. In addition, there is no scratch related damage initiations found on the samples which were treated by Advanced Mitigation Process.

  2. Advanced Mitigation Process (AMP) for Improving Laser Damage Threshold of Fused Silica Optics

    PubMed Central

    Ye, Xin; Huang, Jin; Liu, Hongjie; Geng, Feng; Sun, Laixi; Jiang, Xiaodong; Wu, Weidong; Qiao, Liang; Zu, Xiaotao; Zheng, Wanguo

    2016-01-01

    The laser damage precursors in subsurface of fused silica (e.g. photosensitive impurities, scratches and redeposited silica compounds) were mitigated by mineral acid leaching and HF etching with multi-frequency ultrasonic agitation, respectively. The comparison of scratches morphology after static etching and high-frequency ultrasonic agitation etching was devoted in our case. And comparison of laser induce damage resistance of scratched and non-scratched fused silica surfaces after HF etching with high-frequency ultrasonic agitation were also investigated in this study. The global laser induce damage resistance was increased significantly after the laser damage precursors were mitigated in this case. The redeposition of reaction produce was avoided by involving multi-frequency ultrasonic and chemical leaching process. These methods made the increase of laser damage threshold more stable. In addition, there is no scratch related damage initiations found on the samples which were treated by Advanced Mitigation Process. PMID:27484188

  3. The Effect of High-Pressure Devitrification and Densification on Ballistic-Penetration Resistance of Fused Silica

    NASA Astrophysics Data System (ADS)

    Grujicic, M.; Avuthu, V.; Snipes, J. S.; Ramaswami, S.; Galgalikar, R.

    2015-12-01

    Recent experimental and molecular-level computational analyses have indicated that fused silica, when subjected to pressures of several tens of GPa, can experience irreversible devitrification and densification. Such changes in the fused-silica molecular-level structure are associated with absorption and/or dissipation of the strain energy acquired by fused silica during high-pressure compression. This finding may have important practical consequences in applications for fused silica such as windshields and windows of military vehicles, portholes in ships, ground vehicles, spacecraft, etc. In the present work, our prior molecular-level computational results pertaining to the response of fused silica to high pressures (and shear stresses) are used to enrich a continuum-type constitutive model (that is, the so-called Johnson-Holmquist-2, JH2, model) for this material. Since the aforementioned devitrification and permanent densification processes modify the response of fused silica to the pressure as well as to the deviatoric part of the stress, changes had to be made in both the JH2 equation of state and the strength model. To assess the potential improvements in respect to the ballistic-penetration resistance of this material brought about by the fused-silica devitrification and permanent densification processes, a series of transient non-linear dynamics finite-element analyses of the transverse impact of a fused-silica test plate with a solid right-circular cylindrical steel projectile were conducted. The results obtained revealed that, provided the projectile incident velocity and, hence, the attendant pressure, is sufficiently high, fused silica can undergo impact-induced devitrification, which improves its ballistic-penetration resistance.

  4. Effect of polishing induced subsurface damages on laser induced damage in fused silica optics

    NASA Astrophysics Data System (ADS)

    He, Xiang; Zhao, Heng; Huang, Ying; Cai, Chao; Hu, JiangChuan; Ma, Ping

    2016-10-01

    Conventional used ceria polishing would induce both of Ce contaminants and subsurface damages, which mainly restricts the laser induced damage resistance of fused silica optics. To control the near surface defects, nanometer sized colloidal silica are used to polish fused silica optics after the normal ceria polishing process. Then the contaminant elements and subsurface damages of the polished samples were analyzed by secondary ion mass spectrometry and Nomarski microscopy. It reveals that ceria polishing would introduce lots of subsurface damages whereas colloidal silica polishing induces much fewer subsurface damages especially no fracture induced severe subsurface damages. The laser damage tests reveal that subsequent colloidal silica polishing of the ceria pre-polished samples could gradually eliminate the ceria polishing induced subsurface damages and lower the laser induced damage density accordingly with the increased polishing time. But unlike the damage density, only the severe subsurface damages are totally eliminated could the damage threshold be substantially improved. These results incline to indicate that the subsurface damages have great influence on the laser induced damage density and the fracture related severe subsurface damages will greatly restrict the damage threshold in polished optics.

  5. Origin of the damage ring pattern in fused silica induced by multiple longitudinal modes laser pulses

    NASA Astrophysics Data System (ADS)

    Chambonneau, M.; Diaz, R.; Grua, P.; Rullier, J.-L.; Duchateau, G.; Natoli, J.-Y.; Lamaignère, L.

    2014-01-01

    Ring patterns surrounding laser damage sites at the exit surface of fused silica are systematically observed when initiated by multiple longitudinal modes nanosecond laser pulses at 1064 nm. The appearance chronology of rings is found to be closely related to the temporal shape of the laser pulses. This supports that the damage morphology originates from the coupling of a laser-supported detonation wave propagating in air with an ablation mechanism in silica. In our experiments, the propagation speed of the detonation wave reaches about 20 km/s and scales as the cube root of the laser intensity, in good agreement with theory.

  6. Studies on transmitted beam modulation effect from laser induced damage on fused silica optics.

    PubMed

    Zheng, Yi; Ma, Ping; Li, Haibo; Liu, Zhichao; Chen, Songlin

    2013-07-15

    UV laser induced damage (LID) on exit surface of fused silica could cause modulation effect to transmitted beam and further influence downstream propagation properties. This paper presents our experimental and analytical studies on this topic. In experiment, a series of measurement instruments are applied, including beam profiler, interferometer, microscope, and optical coherent tomography (OCT). Creating and characterizing of LID on fused silica sample have been implemented. Morphological features are studied based on their particular modulation effects on transmitted beam. In theoretical investigation, analytical modeling and numerical simulation are performed. Modulation effects from amplitude, phase, and size factors are analyzed respectively. Furthermore, we have novelly designed a simplified polygon model to simulate actual damage site with multiform modulation features, and the simulation results demonstrate that the modeling is usable and representative.

  7. Birefringence and residual stress induced by CO2 laser mitigation of damage growth in fused silica

    NASA Astrophysics Data System (ADS)

    Gallais, L.; Cormont, P.; Rullier, J. L.

    2009-10-01

    We investigate the residual stress field created near mitigated sites and its influence on the efficiency on the CO2 laser mitigation of damage growth process. A numerical model of CO2 laser interaction with fused silica is developed that take into account laser energy absorption, heat transfer, thermally-induced stress and birefringence. Specific photoelastic methods are developed to characterize the residual stress near mitigated sites in fused silica samples. The stress distribution and quantitative values of stress levels are obtained for sites treated with the CO2 laser in various conditions of energy deposition (beam size, pulse duration, incident power). The results obtained also show that the presence of birefringence/residual stress around the mitigated sites has a critical effect on their laser damage resistance.

  8. Fracture Induced Sub-Band Absorption as a Precursor to Optical Damage on Fused Silica Surfaces

    SciTech Connect

    Miller, P E; Bude, J D; Suratwala, T I; Shen, N; Laurence, T A; Steele, W A; Menapace, J; Feit, M D; Wong, L L

    2010-03-05

    The optical damage threshold of indentation induced flaws on fused silica surfaces was explored. Mechanical flaws were characterized by laser damaged testing, SEM, optical, and photoluminescence microscopy. Localized polishing, chemical etching, and the control of indentation morphology were used to isolate the structural features which limit optical damage. A thin defect layer on fracture surfaces, including those smaller than the wavelength of visible light, was found to be the dominant source of laser damage initiation during illumination with 355nm, 3ns laser pulses. Little evidence was found that either displaced or densified material or fluence intensification plays a significant role in optical damage at fluences >35J/cm{sup 2}. Elimination of the defect layer was shown to increase the overall damage performance of fused silica optics.

  9. Controllable damping of high-Q violin modes in fused silica suspension fibers

    NASA Astrophysics Data System (ADS)

    Dmitriev, A. V.; Mescheriakov, S. D.; Tokmakov, K. V.; Mitrofanov, V. P.

    2010-01-01

    Fused silica fiber suspension of the test masses will be used in the interferometric gravitational wave detectors of the next generation. This allows a significant reduction of losses in the suspension and thermal noise associated with the suspension. Unfortunately, unwanted violin modes may be accidentally excited in the suspension fibers. The Q-factor of the violin modes also exceeds 108. They have a ring-down time that is too long and may complicate the stable control of the interferometer. Results of the investigation of a violin mode active damping system are described. An original sensor and actuator were especially developed to realize the effective coupling of a thin, optically transparent, non-conducting fused silica fiber with an electric circuit. The damping system allowed the changing of the violin mode's damping rate over a wide range.

  10. Microwave interrogated large core fused silica fiber Michelson interferometer for strain sensing.

    PubMed

    Hua, Liwei; Song, Yang; Huang, Jie; Lan, Xinwei; Li, Yanjun; Xiao, Hai

    2015-08-20

    A Michelson-type large core optical fiber sensor has been developed, which is designed based on the optical carrier-based microwave interferometry technique, and fabricated by using two pieces of 200-μm diameter fused silica core fiber as two arms of the Michelson interferometer. The interference fringe pattern caused by the optical path difference of the two arms is interrogated in the microwave domain, where the fringe visibility of 40 dB has easily been obtained. The strain sensing at both room temperature and high temperatures has been demonstrated by using such a sensor. Experimental results show that this sensor has a linear response to the applied strain, and also has relatively low temperature-strain cross talk. The dopant-free quality of the fused silica fiber provides high possibility for the sensor to have promising strain sensing performance in a high temperature environment.

  11. Polarizing beam splitter of deep-etched triangular-groove fused-silica gratings.

    PubMed

    Zheng, Jiangjun; Zhou, Changhe; Feng, Jijun; Wang, Bo

    2008-07-15

    We investigated the use of a deep-etched fused-silica grating with triangular-shaped grooves as a highly efficient polarizing beam splitter (PBS). A triangular-groove PBS grating is designed at a wavelength of 1550 nm to be used in optical communication. When it is illuminated in Littrow mounting, the transmitted TE- and TM-polarized waves are mainly diffracted in the minus-first and zeroth orders, respectively. The design condition is based on the average differences of the grating mode indices, which is verified by using rigorous coupled-wave analysis. The designed PBS grating is highly efficient over the C+L band range for both TE and TM polarizations (>97.68%). It is shown that such a triangular-groove PBS grating can exhibit a higher diffraction efficiency, a larger extinction ratio, and less reflection loss than the binary-phase fused-silica PBS grating.

  12. Dimensional Stability of Fused Silica, Invar, and Several Ultralow Thermal Expansion Materials

    DTIC Science & Technology

    1976-01-01

    evacuated environments at constant temperature (near 300 K). Materials were two types of fused silica, Cer-Vit, ULE, Zerodur , Invar, and Super Invar...Constant Temperature Cer-Vit ULE Zerodur Optics Interface Drift Dielectric Coating Pages: 00040 Cataloged Date: Nov 20,1992 Document Type: HC Number...changes. These include Owens-Illinois Cer-Vit C-101, Corning ULE 7971, and Schott Zerodur , whose thermal expansion coefficients are exceedingly low over a

  13. The Formation of the Second-Order Nonlinearity in Thermally Poled Fused Silica Glass

    DTIC Science & Technology

    2007-11-02

    NONIINEARITY IN THERMALLY POLED FUSED SILICA GLASS 6. AUTHOR(S) THOMAS GUSTAVE ALLEY 5. FUNDING NUMBERS 7. PERFORMING ORGANIZATION NAME(S) AND...ADDRESS(ES) The University of New Mexico 8. PERFORMING ORGANIZATION REPORT NUMBER 98-020D 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES...self- organized , photoinduced, second-order nonlinearity. The most widely accepted explanation attributes the nonlinearity to an asymmetric

  14. Fused Silica Ion Trap Chip with Efficient Optical Collection System for Timekeeping, Sensing, and Emulation

    DTIC Science & Technology

    2015-01-22

    micromachining technology base, we had very limited metal coating experience. Obtaining the relevant know-how was a crucial part of this program and an...parallel with this program, using fabrication processes (partially) developed during this STTR, we have fabricated traps for the in-situ coating and...various liquid etchants (chemical etching rates can be increase one-hundred-fold over that of unaltered fused silica). The former process

  15. Heat accumulation regime of femtosecond laser writing in fused silica and Nd:phosphate glass

    NASA Astrophysics Data System (ADS)

    Bukharin, M. A.; Khudyakov, D. V.; Vartapetov, S. K.

    2015-04-01

    We investigated refractive index induced by direct femtosecond laser writing inside fused silica and Nd:phosphate glass in heat accumulation regime. Spatial profile and magnitude of induced refractive index were investigated at various pulse repetition rates and translation velocities. It was shown that the magnitude of induced refractive index significantly rises with decreasing in time interval between successive laser pulses below the time for thermal diffusion. Going from nonthermal regime to heat accumulation regime, we achieved induced refractive index growth from 4 × 10-3 up to 6.5 × 10-3 in fused silica and from -6 × 10-3 to -9 × 10-3 in Nd:phosphate glass. Aspect ratio of treated area decreased from 2.1 down to less than 1.5 without correcting optical elements. It was shown that in heat accumulation regime, the treated area was surrounded by region of alternatively changed refractive index with significant magnitude up to -2 × 10-3. Wide regions of decreased refractive index enable fabrication of depressed cladding waveguides. We demonstrated low-loss (0.3 dB/cm) tubular waveguide inside fused silica. For orthogonal polarizations of guiding light, we achieved a small difference between losses as 0.1 dB/cm using highly symmetric written tracks forming the cladding. The desired structure was simulated with the beam propagation method, and the results were in good agreement with experiment data.

  16. Ultradeep fused silica glass etching with an HF-resistant photosensitive resist for optical imaging applications

    NASA Astrophysics Data System (ADS)

    Nagarah, John M.; Wagenaar, Daniel A.

    2012-03-01

    Microfluidic and optical sensing platforms are commonly fabricated in glass and fused silica (quartz) because of their optical transparency and chemical inertness. Hydrofluoric acid (HF) solutions are the etching media of choice for deep etching into silicon dioxide substrates, but processing schemes become complicated and expensive for etching times greater than 1 h due to the aggressiveness of HF migration through most masking materials. We present here etching into fused silica more than 600 µm deep while keeping the substrate free of pits and maintaining a polished etched surface suitable for biological imaging. We utilize an HF-resistant photosensitive resist (HFPR) which is not attacked in 49% HF solution. Etching characteristics are compared for substrates masked with the HFPR alone and the HFPR patterned on top of Cr/Au and polysilicon masks. We used this etching process to fabricate suspended fused silica membranes, 8-16 µm thick, and show that imaging through the membranes does not negatively affect image quality of fluorescence microscopy of biological tissue. Finally, we realize small through-pore arrays in the suspended membranes. Such devices will have applications in planar electrophysiology platforms, especially where optical imaging is required.

  17. Single-Molecule Imaging of DNAs with Sticky Ends at Water/Fused Silica Interface

    SciTech Connect

    Isailovic, Slavica

    2005-01-01

    Total internal reflection fluorescence microscopy (TIRFM) was used to study intermolecular interactions of DNAs with unpaired (sticky) ends of different lengths at water/fused silica interface at the single-molecule level. Evanescent field residence time, linear velocity and adsorption/desorption frequency were measured in a microchannel for individual DNA molecules from T7, Lambda, and PSP3 phages at various pH values. The longest residence times and the highest adsorption/desorption frequencies at the constant flow at pH 5.5 were found for PSP3 DNA, followed by lower values for Lambda DNA, and the lowest values for T7 DNA. Since T7, Lambda, and PSP3 DNA molecules contain none, twelve and nineteen unpaired bases, respectively, it was concluded that the affinity of DNAs for the surface increases with the length of the sticky ends. This confirms that hydrophobic and hydrogen-bonding interactions between sticky ends and fused-silica surface are driving forces for DNA adsorption at the fused-silica surface. Described single-molecule methodology and results therein can be valuable for investigation of interactions in liquid chromatography, as well as for design of DNA hybridization sensors and drug delivery systems.

  18. Capillary electrophoresis in a fused-silica capillary with surface roughness gradient.

    PubMed

    Horká, Marie; Šlais, Karel; Karásek, Pavel; Růžička, Filip; Šalplachta, Jiří; Šesták, Jozef; Kahle, Vladislav; Roth, Michal

    2016-10-01

    The electro-osmotic flow, a significant factor in capillary electrophoretic separations, is very sensitive to small changes in structure and surface roughness of the inner surface of fused silica capillary. Besides a number of negative effects, the electro-osmotic flow can also have a positive effect on the separation. An example could be fused silica capillaries with homogenous surface roughness along their entire separation length as produced by etching with supercritical water. Different strains of methicillin-resistant and methicillin-susceptible Staphylococcus aureus were separated on that type of capillaries. In the present study, fused-silica capillaries with a gradient of surface roughness were prepared and their basic behavior was studied in capillary zone electrophoresis with UV-visible detection. First the influence of the electro-osmotic flow on the peak shape of a marker of electro-osmotic flow, thiourea, has been discussed. An antifungal agent, hydrophobic amphotericin B, and a protein marker, albumin, have been used as model analytes. A significant narrowing of the detected zones of the examined analytes was achieved in supercritical-water-treated capillaries as compared to the electrophoretic separation in smooth capillaries. Minimum detectable amounts of 5 ng/mL amphotericin B and 5 μg/mL albumin were reached with this method.

  19. Laser-induced circular nanostructures in fused silica assisted by a self-assembling chromium layer

    NASA Astrophysics Data System (ADS)

    Lorenz, Pierre; Klöppel, Michael; Frost, Frank; Ehrhardt, Martin; Zimmer, Klaus; Li, Pu

    2013-09-01

    Nanostructures have a widespread field of applications and are of growing industrial importance. However, the economic fabrication of nanostructures poses a critical challenge. In this work, a fundamental research of a laser-induced surface nanostructuring of fused silica using the dynamic self-assembling structure formation in metal layers is presented. This method may offer promising opportunities for nanostructuring of dielectrics. This new approach is demonstrated by the formation of randomly distributed concentric nanostructures into fused silica. The irradiation of chromium-covered fused silica samples with a KrF excimer laser results in melting, partial ablation, restructuring, and resolidification of both the metal layer and the dielectric surface. In this way, concentric circular structures into the dielectric were formed with dimensions that can be controlled by the laser fluence Φ and by the pulse number N. The distance of the concentric rings increases with increasing laser fluence. The experimental results were compared with simulated structure dimensions taking into account the heat equation and the Navier-Stokes equation. Despite the currently applied decoupled approach for the simulations, i.e. separating the heat equation and the fluid flow, a good agreement of simulation results with experimental data was achieved.

  20. Polarizing beam splitter of a deep-etched fused-silica grating.

    PubMed

    Wang, Bo; Zhou, Changhe; Wang, Shunquan; Feng, Jijun

    2007-05-15

    We described a highly efficient polarizing beam splitter (PBS) of a deep-etched binary-phase fused-silica grating, where TE- and TM-polarized waves are mainly diffracted in the -1st and 0th orders, respectively. To achieve a high extinction ratio and diffraction efficiency, the grating depth and period are optimized by using rigorous coupled-wave analysis, which can be well explained based on the modal method with effective indices of the modes for TE/TM polarization. Holographic recording technology and inductively coupled plasma etching are employed to fabricate the fused-silica PBS grating. Experimental results of diffraction efficiencies approaching 80% for a TE-polarized wave in the -1st order and more than 85% for a TM-polarized wave in the 0th order were obtained at a wavelength of 1550 nm. Because of its compact structure and simple fabrication process, which is suitable for mass reproduction, a deep-etched fused-silica grating as a PBS should be a useful device for practical applications.

  1. Measurement of initial absorption of fused silica at 193nm using laser induced deflection technique (LID)

    NASA Astrophysics Data System (ADS)

    Schönfeld, Dörte; Klett, Ursula; Mühlig, Christian; Thomas, Stephan

    2008-01-01

    The ongoing development in microlithography towards further miniaturization of structures creates a strong demand for lens material with nearly ideal optical properties. Beside the highly demanding requirements on homogeneity and stress induced birefringence (SIB), low absorption is a key factor. Even a small absorption is associated with a temperature increase and results in thermally induced local variations of refractive index and SIB. This could affect the achievable resolution of the lithographic process. The total absorption of the material is composed of initial absorption and of absorption induced during irradiation. Thus, the optimization of both improves the lifetime of the material. In principal, it is possible to measure transmission and scattering with a suitable spectrometer assembly and calculate absorption from them. However, owing to the influence of sample surfaces and errors of measurement, these methods usually do not provide satisfactory results for highly light-transmissive fused silica. Therefore, it is most desirable to find a technique that is capable of directly measuring absorption coefficients in the range of (1...10)•10 -4 cm -1 (base 10) directly. We report our first results for fused silica achieved with the LID technique. Besides a fused silica grade designed for 193 nm applications, grades with higher absorption at 193 nm were measured to test the LID technique. A special focus was set on the possibility of measuring initial absorption without the influence of degradation effects.

  2. Formation of cylindrical micro-lens array in fused silica glass using laser irradiations

    NASA Astrophysics Data System (ADS)

    Choi, Hun-Kook; Ahsan, Md. Shamim; Yoo, Dongyoon; Sohn, Ik-Bu; Noh, Young-Chul; Kim, Jin Tae; Jung, Deok; Kim, Jin Hyeok

    2013-12-01

    In this article, we report the development of plano-convex cylindrical micro-lens array on the surface of fused silica glass using laser processing technology. Initially, femtosecond laser pulses are irradiated on the target fused silica glass substrate to pattern periodic micro-grooves. Afterwards, laser beam from CO2 laser source is applied several times on the previously micro-patterned fused silica glass surface, the purpose of which is to polish the micro-patterned glass surface. As a consequence, periodic plano-convex cylindrical micro-lens array is evolved on the glass surface. The micro-lens array shows great consistency in size and shape throughout the sample area. We also investigate various optical properties of the micro-lenses evolved glass substrates including the diffraction pattern and diffraction efficiency of light. The glass sample comprising cylindrical micro-lens array can diffract light with moderate diffraction efficiency. We strongly believe that, it is possible to engineer cylindrical micro-lens array on the surface of a variety of transparent materials including glasses and polymers over a large area.

  3. Laser-welded fused silica substrates using a luminescent fresnoite-based sealant

    NASA Astrophysics Data System (ADS)

    de Pablos-Martin, A.; Benndorf, G.; Tismer, S.; Mittag, M.; Cismak, A.; Lorenz, M.; Grundmann, M.; Höche, Th.

    2016-06-01

    The laser welding of two fused silica substrates using a fresnoitic glass thin film as a sealant by irradiation with a ns laser is studied. Two different laser parameter sets were compared in terms of bond quality, which include two different laser beam trajectories: linear and wobble (circular) trajectory. The composition of the glass sealant changes with the course of the laser welding, incorporating silica from the substrates. After joining, the bonded samples were exposed to UV light and a very intense emission in the blue spectral range is observed by naked eye, which is due to the crystallization of the fresnoite glass upon the laser irradiation. EDX analysis confirms the crystallization of fresnoite, together with a great enrichment in silica. The formation of a eutectic between both is very plausible. Bond quality and bond strength were evaluated by scanning acoustic microscopy (SAM) and tensile test, which results in a tensile stress of 7 MPa.

  4. Contamination resistant antireflection nano-textures in fused silica for laser optics

    NASA Astrophysics Data System (ADS)

    Hobbs, Douglas S.; MacLeod, Bruce D.; Sabatino, Ernest; Britten, Jerald A.; Stolz, Christopher J.

    2013-11-01

    Anti-reflecting (AR) surface relief nano-textures have been integrated with fused silica diffraction gratings to demonstrate the potential of stable diffractive 3ω beam samplers with increased energy to target at the National Ignition Facility (NIF). TelAztec's AR texturing process was used to etch Random-type AR (RAR) microstructures in sub-scale NIF Grating Debris Shields consisting of large pitch, shallow line gratings. This superposition yielded the desired ~3.5% increase in zero-order transmission uniformly over the full aperture without compromising the grating function. Another fused silica window fabricated with RAR nano-textures in both faces for a 3ω (351nm) transmission of 99.5%, was subjected to capillary condensation tests to evaluate the resistance of the RAR texture to the adsorption of organic compounds. It was found that for a one day exposure time to a surrogate suite of organic contaminants, the RAR textured fused silica surfaces adsorbed less than one fourth the amount of organic contaminants found on a NIF baseline hardened sol-gel AR coated optic. In two additional exposure cycles, further RAR process refinement reduced the amount of adsorbed organics to a level nearly 200 times below the current NIF baseline. Significantly, the 3ω transmission of the RAR textured window remained unchanged after all three exposure cycles, whereas the sol-gel coated windows showed losses up to 4.9% for the highest contaminant concentration. Large beam pulsed laser damage testing of RAR textured fused silica windows was conducted with the Optical Sciences Laser (OSL) at NIF. The RAR sample damage resistance was found to be equivalent to the current NIF baseline - even after multiple aggressive chemical cleaning cycles. Lastly, a series of RAR textured and sol-gel AR coated windows were subjected to commercial 3ω pulsed laser damage testing at Quantel. The results indicate an average RAR damage threshold of 26 J/cm2, a level about 80% of the two NIF fused

  5. A new method for synthesizing fluid inclusions in fused silica capillaries containing organic and inorganic material

    USGS Publications Warehouse

    Chou, I.-Ming; Song, Y.; Burruss, R.C.

    2008-01-01

    Considerable advances in our understanding of physicochemical properties of geological fluids and their roles in many geological processes have been achieved by the use of synthetic fluid inclusions. We have developed a new method to synthesize fluid inclusions containing organic and inorganic material in fused silica capillary tubing. We have used both round (0.3 mm OD and 0.05 or 0.1 mm ID) and square cross-section tubing (0.3 ?? 0.3 mm with 0.05 ?? 0.05 mm or 0.1 ?? 0.1 mm cavities). For microthermometric measurements in a USGS-type heating-cooling stage, sample capsules must be less than 25 mm in length. The square-sectioned capsules have the advantage of providing images without optical distortion. However, the maximum internal pressure (P; about 100 MPa at 22 ??C) and temperature (T; about 500 ??C) maintained by the square-sectioned capsules are less than those held by the round-sectioned capsules (about 300 MPa at room T, and T up to 650 ??C). The fused silica capsules can be applied to a wide range of problems of interest in fluid inclusion and hydrothermal research, such as creating standards for the calibration of thermocouples in heating-cooling stages and frequency shifts in Raman spectrometers. The fused silica capsules can also be used as containers for hydrothermal reactions, especially for organic samples, including individual hydrocarbons, crude oils, and gases, such as cracking of C18H38 between 350 and 400 ??C, isotopic exchanges between C18H38 and D2O and between C19D40 and H2O at similar temperatures. Results of these types of studies provide information on the kinetics of oil cracking and the changes of oil composition under thermal stress. When compared with synthesis of fluid inclusions formed by healing fractures in quartz or other minerals or by overgrowth of quartz at elevated P-T conditions, the new fused-silica method has the following advantages: (1) it is simple; (2) fluid inclusions without the presence of water can be formed; (3

  6. Thermal transport in CO2 laser irradiated fused silica: in situ measurements and analysis

    SciTech Connect

    Yang, S T; Matthews, M J; Elhadj, S; Draggoo, V G; Bisson, S E

    2009-07-07

    In situ spatial and temporal temperature measurements of pristine fused silica surfaces heated with a 10.6 {micro}m CO{sub 2} laser were obtained using an infrared radiation thermometer based on a Mercury Cadmium Telluride (MCT) camera. Laser spot sizes ranged from 250 {micro}m to 1000 {micro}m diameter with peak axial irradiance levels of 0.13 to 16 kW/cm{sup 2}. For temperatures below 2800K, the measured steady-state surface temperature is observed to rise linearly with both increasing beam size and incident laser irradiance. The effective thermal conductivity estimated over this range was approximately 2W/mK, in good agreement with classical calculations based on phonon heat capacities. Similarly, time-dependent temperature measurements up to 2000K yielded thermal diffusivity values which were close to reported values of 7 x 10{sup -7} m{sup 2}/s. Above {approx}2800K, the fused silica surface temperature asymptotically approaches 3100K as laser power is further increased, consistent with the onset of evaporative heat losses near the silica boiling point. These results show that in the laser heating regime studied here, the T{sup 3} temperature dependent thermal conductivity due to radiation transport can be neglected, but at temperatures above 2800K heat transport due to evaporation must be considered. The thermal transport in fused silica up to 2800K, over a range of conditions, can then be adequately described by a linear diffusive heat equation assuming constant thermal properties.

  7. Correlation of polishing-induced shallow subsurface damages with laser-induced gray haze damages in fused silica optics

    NASA Astrophysics Data System (ADS)

    He, Xiang; Zhao, Heng; Wang, Gang; Zhou, Peifan; Ma, Ping

    2016-08-01

    Laser-induced damage in fused silica optics greatly restricts the performances of laser facilities. Gray haze damage, which is always initiated on ceria polished optics, is one of the most important damage morphologies in fused silica optics. In this paper, the laser-induced gray haze damages of four fused silica samples polished with CeO2, Al2O3, ZrO2, and colloidal silica slurries are investigated. Four samples all present gray haze damages with much different damage densities. Then, the polishing-induced contaminant and subsurface damages in four samples are analyzed. The results reveal that the gray haze damages could be initiated on the samples without Ce contaminant and are inclined to show a tight correlation with the shallow subsurface damages.

  8. Comparing study of subpicosecond and nanosecond wet etching of fused silica

    NASA Astrophysics Data System (ADS)

    Vass, Cs.; Sebők, D.; Hopp, B.

    2006-04-01

    The effectiveness of the laser induced backside wet etching (LIBWE) of fused silica produced by subpicosecond (600 fs) and nanosecond (30 ns) KrF excimer laser pulses (248 nm) was studied. Fused silica plates were the transparent targets, and naphthalene-methyl-methacrylate ( c = 0.85, 1.71 M) and pyrene-acetone ( c = 0.4 M) solutions were used as liquid absorbents. We did not observe etching using 600 fs laser pulses, in contrast with the experiments at 30 ns, where etched holes were found. The threshold fluences of the LIBWE at nanosecond pulses were found to be in the range of 360-450 mJ cm -2 depending on the liquid absorbers and their concentrations. On the basis of the earlier results the LIBWE procedure can be explain by the thermal heating of the quartz target and the high-pressure bubble formation in the liquid. According to the theories, these bubbles hit and damage the fused silica surface. The pressure on the irradiated quartz can be derived from the snapshots of the originating and expanding bubbles recorded by fast photographic setup. We found that the bubble pressure at 460 mJ cm -2 fluence value was independent of the pulse duration (600 fs and 30 ns) using pyrene-acetone solution, while using naphthalene-methyl-methacrylate solutions this pressure was 4, 5 times higher at 30 ns pulses than it was at 600 fs pulses. According to the earlier studies, this result refers to that the pressure should be sufficiently high to remove a thin layer from the quartz surface using pyrene-acetone solution. These facts show that the thermal and chemical phenomena in addition to the mechanical effects also play important role in the LIBWE procedure.

  9. Femtosecond laser fabrication of birefringent directional couplers as polarization beam splitters in fused silica.

    PubMed

    Fernandes, Luís A; Grenier, Jason R; Herman, Peter R; Aitchison, J Stewart; Marques, Paulo V S

    2011-06-20

    Integrated polarization beam splitters based on birefringent directional couplers are demonstrated. The devices are fabricated in bulk fused silica glass by femtosecond laser writing (300 fs, 150 nJ at 500 kHz, 522 nm). The birefringence was measured from the spectral splitting of the Bragg grating resonances associated with the vertically and horizontally polarized modes. Polarization splitting directional couplers were designed and demonstrated with 0.5 dB/cm propagation losses and -19 dB and -24 dB extinction ratios for the polarization splitting.

  10. Subsurface mechanical damage during bound abrasive grinding of fused silica glass

    NASA Astrophysics Data System (ADS)

    Blaineau, P.; André, D.; Laheurte, R.; Darnis, P.; Darbois, N.; Cahuc, O.; Neauport, J.

    2015-10-01

    The subsurface damage (SSD) introduced during bound abrasive grinding of fused silica glass was measured using a wet etch technique. Various process parameters and grinding configurations were studied. The relation between the SSD depth, the process parameters and forces applied by the grinding wheel on the sample was investigated and compared to a simulation using a discrete element method to model the grinding interface. The results reveal a relation between the SSD depth and the grinding forces normalized by the abrasive concentration. Regarding the creation of the SSD, numerical simulations indicate that only a small fraction of the largest particles in the diamond wheel are responsible for the depth of the damaged layer.

  11. Initiation, Growth and Mitigation of UV Laser Induced Damage in Fused Silica

    SciTech Connect

    Rubenchik, A M; Feit, M D

    2003-06-10

    Laser damage of large fused silica optics initiates at imperfections. Possible initiation mechanisms are considered. We demonstrate that a model based on nanoparticle explosions is consistent with the observed initiation craters. Possible mechanisms for growth upon subsequent laser irradiation, including material modification and laser intensification, are discussed. Large aperture experiments indicate an exponential increase in damage size with number of laser shots. Physical processes associated with this growth and a qualitative explanation of self-accelerated growth is presented. Rapid growth necessitates damage growth mitigation techniques. Several possible mitigation techniques are mentioned, with special emphasis on CO{sub 2} processing. Analysis of material evaporation, crack healing, and thermally induced stress are presented.

  12. Initiation, Growth and Mitigation of UV Laser Induced Damage in Fused Silica

    SciTech Connect

    Rubenchik, A M; Feit, M D

    2001-12-21

    Laser damage of large fused silica optics initiates at imperfections. Possible initiation mechanisms are considered. We demonstrate that a model based on nanoparticle explosions is consistent with the observed initiation craters. Possible mechanisms for growth upon subsequent laser irradiation, including material modification and laser intensification, are discussed. Large aperture experiments indicate an exponential increase in damage size with number of laser shots. Physical processes associated with this growth and a qualitative explanation of self-accelerated growth is presented. Rapid growth necessitates damage growth mitigation techniques. Several possible mitigation techniques are mentioned, with special emphasis on CO{sub 2} processing. Analysis of material evaporation, crack healing, and thermally induced stress are presented.

  13. Control of laser filamentation in fused silica by a periodic microlens array.

    PubMed

    Camino, Acner; Hao, Zuoqiang; Liu, Xu; Lin, Jingquan

    2013-04-08

    Deterministic wavelength-dependent multifilamentation is controlled in fused silica by adjusting the diffraction pattern generated by a loosely focusing 2D periodic lens array. By simply translating the sample along the propagation axis the number and distribution of filaments can be controlled and are in agreement with the results of linear diffraction simulations. The loose focusing geometry allows for long filaments whose distribution is conserved along their propagation inside the sample. The effect of incident energy and polarization on filament number is also studied. Laser filamentation controlled by a microlens array could be a promising method for easy and fast 3D track writing in transparent materials.

  14. Femtosecond laser fabrication of phase-shifted Bragg grating waveguides in fused silica.

    PubMed

    Grenier, Jason R; Fernandes, Luís A; Aitchison, J Stewart; Marques, Paulo V S; Herman, Peter R

    2012-06-15

    Phase-shifted Bragg grating waveguides (PSBGWs) were formed in bulk fused silica glass by femtosecond laser direct writing to produce narrowband (22±3)  pm filters at 1550 nm. Tunable π and other phase shifts generated narrow passbands in controlled positions of the Bragg stopband, while the accurate placement of multiple cascaded phase-shift regions yielded a rectangular-shaped bandpass filter. A waveguide birefringence of (7.5±0.3)×10(-5) is inferred from the polarization-induced spectral shifting of the PSBGW narrowband filters.

  15. Dimensional stability of fused silica, Invar, and several ultralow thermal expansion materials

    NASA Technical Reports Server (NTRS)

    Berthold, J. W., III; Jacobs, S. F.; Norton, M. A.

    1976-01-01

    A method is developed for testing the long-term dimensional stability of an iodine-stabilized He-Ne laser, using a technique whereby thermal expansion coefficients are measured by forming a Fabry-Perot etalon from the sample and monitoring the optical resonant frequencies with tunable sidebands impressed on a laser beam from a frequency-stabilized He-Ne laser. A change of 1 ppm over a 3-yr period on the part of fused silica dimensions and the differential thermal expansion of Invar LR-35 and Super Invar materials are noted. The method is of interest for the metrology of extremely stable structures such as telescopes and optical resonators.

  16. Thermal poling induced second-order nonlinearity in femtosecond- laser-modified fused silica

    SciTech Connect

    An Honglin; Fleming, Simon; McMillen, Benjamin W.; Chen, Kevin P.; Snoke, David

    2008-08-11

    Thermal poling was utilized to induce second-order nonlinearity in regions of fused silica modified by 771 nm femtosecond laser pulses. With second-harmonic microscopy, it was found that the nonlinearity in the laser-modified region was much lower than that in nonmodified regions. This is attributed to a more rigid glass network after irradiation by the femtosecond laser pulses and/or lack of mobile alkali ions. Measurement of the distribution of chemical elements in the femtosecond-laser-modified region in a soda lime glass revealed a lower level of sodium ions.

  17. Role of suprathermal electrons during nanosecond laser energy deposit in fused silica

    SciTech Connect

    Grua, P.; Hébert, D.; Lamaignère, L.; Rullier, J.-L.

    2014-08-25

    An accurate description of interaction between a nanosecond laser pulse and a wide band gap dielectric, such as fused silica, requires the understanding of energy deposit induced by temperature changes occurring in the material. In order to identify the fundamental processes involved in laser-matter interaction, we have used a 1D computational model that allows us to describe a wide set of physical mechanisms and intended for comparison with specially designed “1D experiments.” We have pointed out that suprathermal electrons are very likely implicated in heat conduction, and this assumption has allowed the model to reproduce the experiments.

  18. Visible supercontinuum radiation of light bullets in the femtosecond filamentation of IR pulses in fused silica

    SciTech Connect

    Chekalin, S V; Kompanets, V O; Dokukina, A E; Dormidonov, A E; Smetanina, E O; Kandidov, V P

    2015-05-31

    We report experimental and theoretical investigations of visible supercontinuum generation in the formation of light bullets in a filament produced by IR pulses. In the filamentation of a 1700 – 2200 nm pulse in fused silica, bright tracks are recorded resulting from the recombination glow of carriers in the laser plasma produced by a sequence of light bullets and from the scattering in silica of the visible supercontinuum generated by the light bullets. It is found that the formation of a light bullet is attended with an outburst of a certain portion of supercontinuum energy in the visible range. The energy outburst is the same for all bullets in the sequence and becomes smaller with increasing pulse wavelength. (extreme light fields and their applications)

  19. All-Atom Molecular-Level Analysis of the Ballistic-Impact-Induced Densification and Devitrification of Fused Silica

    NASA Astrophysics Data System (ADS)

    Grujicic, M.; Snipes, J. S.; Ramaswami, S.; Yavari, R.; Barsoum, R. S.

    2015-08-01

    All-atom molecular-level computations are carried out to infer the dynamic response and material microstructure/topology changes of fused silica subjected to ballistic impact by a hard projectile. The analysis was focused on the investigation of specific aspects of the dynamic response and of the microstructural changes such as the deformation of highly sheared and densified regions and the conversion of amorphous fused silica to SiO2 crystalline allotropic modifications (in particular, α-quartz and stishovite). The microstructural changes in question were determined by carrying out a post-processing atom-coordination procedure. This procedure suggested the formation of stishovite (and perhaps α-quartz) within fused silica during ballistic impact. To rationalize the findings obtained, the all-atom molecular-level computational analysis is complemented by a series of quantum-mechanics density functional theory (DFT) computations. The latter computations enable determination of the relative potential energies of the fused silica, α-quartz, and stishovite under ambient pressure (i.e., under their natural densities) as well as under imposed (as high as 50 GPa) pressures (i.e., under higher densities) and shear strains. In addition, the transition states associated with various fused-silica devitrification processes were identified. The results obtained are found to be in good agreement with their respective experimental counterparts.

  20. Formation of conical emission of supercontinuum during filamentation of femtosecond laser radiation in fused silica

    SciTech Connect

    Kandidov, V. P. Smetanina, E. O.; Dormidonov, A. E.; Kompanets, V. O.; Chekalin, S. V.

    2011-09-15

    The formation of conical emission of supercontinuum during filamentation of femtosecond laser pulses with central wavelengths in a wide range is studied experimentally, numerically, and analytically. The frequency-angular intensity distribution of the spectral components of conical emission is determined by the interference of supercontinuum emission in a filament of a femtosecond laser pulse. The interference of supercontinuum emission has a general character, exists at different regimes of group velocity dispersion, gives rise to the fine spectral structure after the pulse splitting into subpulses and the formation of a distributed supercontinuum source in an extended filament, and causes the decomposition of the continuous spectrum of conical emission into many high-contrast maxima after pulse refocusing in the filament. In spectroscopic studies with a tunable femtosecond radiation source based on a TOPAS parametric amplifier, we used an original scheme with a wedge fused silica sample. Numerical simulations have been performed using a system of equations of nonlinear-optical interaction of laser radiation under conditions of diffraction, wave nonstationarity, and material dispersion in fused silica. The analytic study is based on the interference model of formation of conical emission by supercontinuum sources moving in a filament.

  1. Production of submicrometre fused silica gratings using laser-induced backside dry etching technique

    NASA Astrophysics Data System (ADS)

    Hopp, B.; Vass, Cs; Smausz, T.; Bor, Zs

    2006-11-01

    Laser micromachining of transparent materials is a promising technique for producing micro-optical elements. Several types of both direct (e.g. ablation) and indirect (e.g. laser-induced backside wet etching: LIBWE) procedures have already been developed and presented in the last two decades. Here we present a new method (laser-induced backside dry etching (LIBDE)) in the analogy of LIBWE for the micro and nanoprocessing of transparent materials. In our experiments 1 mm thick fused silica plates were used as transparent work pieces. The plates were covered with 100 nm thick silver layers. The metal absorbing films were irradiated through the fused silica by a KrF excimer laser beam (λ = 248 nm, FWHM = 30 ns). The illuminated area was 1.05 mm2 and the fluence on the silver-quartz interface varied in the range 0-1800 mJ cm-2. We have provided evidence that LIBDE is more effective and simple than LIBWE, its etch rate being much higher at a given laser fluence. Our interference experiments proved that the LIBDE etching technique is suitable to fabricate gratings displaying submicrometre periods in transparent materials. On the basis of all these, it is suggested that this method may be useful to produce other nano and microoptical elements, too.

  2. Residual stress near cracks of K and fused silica under 1064 nm nanosecond laser irradiation

    NASA Astrophysics Data System (ADS)

    Zhang, Zhen; Liu, Hongjie; Huang, Jin; Zhou, Xiaoyan; Ren, Dahua; Cheng, Xinlu; Jiang, Xiaodong; Wu, Weidong; Zheng, Wanguo

    2012-11-01

    Measurements of birefringence induced in K9 and fused silica specimens by cracks produced by 1064 nm Nd∶YAG laser have been presented. The Birefringence data is converted into the units of stress, thus permitting the estimation of residual stress near crack. The intensity of residual stress in K9 glass is larger than that in fused silica under the same condition. The similarity of residual stress distribution along the y-axis reveals that the nature of shock wave transmission in optical materials under 1064 nm laser irradiation is the same with each other. The value of residual stress can be influenced by laser parameters and characterization of optical material. Simulation based on a theoretical model giving the residual stress field around a crack is developed for comparison with experiment results. The probability of initial damage and the direction of the energy dissipation in cracks determine the residual stress distribution. The thermal stress coupling enlarges the asymmetry of residual stress distribution. Residual stress in optical material has a strong effect on fracture and should be taken into account in any formulation that involves the enhanced damage resistance of optical components used in laser induced damage experiments.

  3. Downstream Intensification Effects Associated with CO2 Laser Mitigation of Fused Silica

    SciTech Connect

    Matthews, M J; Bass, I L; Guss, G M; Widmayer, C C; Ravizza, F L

    2007-10-29

    Mitigation of 351nm laser-induced damage sites on fused silica exit surfaces by selective CO{sub 2} treatment has been shown to effectively arrest the exponential growth responsible for limiting the lifetime of optics in high-fluence laser systems. However, the perturbation to the optical surface profile following the mitigation process introduces phase contrast to the beam, causing some amount of downstream intensification with the potential to damage downstream optics. Control of the laser treatment process and measurement of the associated phase modulation is essential to preventing downstream 'fratricide' in damage-mitigated optical systems. In this work we present measurements of the surface morphology, intensification patterns and damage associated with various CO{sub 2} mitigation treatments on fused silica surfaces. Specifically, two components of intensification pattern, one on-axis and another off-axis can lead to damage of downstream optics and are related to rims around the ablation pit left from the mitigation process. It is shown that control of the rim structure around the edge of typical mitigation sites is crucial in preventing damage to downstream optics.

  4. Effect of the repaired damage morphology of fused silica on the modulation of incident laser

    NASA Astrophysics Data System (ADS)

    Gao, X.; Jiang, Y.; Qiu, R.; Zhou, Q.; Zuo, R.; Zhou, G. R.; Yao, K.

    2017-02-01

    Local CO2 laser treatment has proved to be the most promising method to extend the life-time of fused silica. However, previous experimental data show that some raised rims are observed around the mitigated sites left from the mitigation process, which will result in hazardous light modulation to the downstream optics. In this work, the morphology features of mitigated sites on the surface of fused silica optics were analyzed in detail. According to measured morphology features, a 3D analytical model for simulating the modulation value induced by mitigated site has been developed based on the scalar diffraction theory. The diffraction patterns at a discrete distance downstream from each mitigated site are measured. The influences of geometry, laser wavelength and refractive index of substrates on the modulation by repaired damage morphology at different distances are discussed, respectively. The analytical model is usable and representative to evaluate the hazardous modulation induced by repaired damage morphology to downstream optics. Results on this research suggest that the downstream intensification can be suppressed by controlling the morphology features of mitigated sites, which provides a direction for the development and improvement of the mitigated techniques of damage optics.

  5. Micro Fluidic Channel Machining on Fused Silica Glass Using Powder Blasting

    PubMed Central

    Jang, Ho-Su; Cho, Myeong-Woo; Park, Dong-Sam

    2008-01-01

    In this study, micro fluid channels are machined on fused silica glass via powder blasting, a mechanical etching process, and the machining characteristics of the channels are experimentally evaluated. In the process, material removal is performed by the collision of micro abrasives injected by highly compressed air on to the target surface. This approach can be characterized as an integration of brittle mode machining based on micro crack propagation. Fused silica glass, a high purity synthetic amorphous silicon dioxide, is selected as a workpiece material. It has a very low thermal expansion coefficient and excellent optical qualities and exceptional transmittance over a wide spectral range, especially in the ultraviolet range. The powder blasting process parameters affecting the machined results are injection pressure, abrasive particle size and density, stand-off distance, number of nozzle scanning, and shape/size of the required patterns. In this study, the influence of the number of nozzle scanning, abrasive particle size, and pattern size on the formation of micro channels is investigated. Machined shapes and surface roughness are measured using a 3-dimensional vision profiler and the results are discussed. PMID:27879730

  6. Laser-induced damage initiated on the surface of particle contamination fused silica at 1064nm

    SciTech Connect

    Michlitsch, K.J.

    1998-06-01

    An experimental study was undertaken to quantify the effects of contamination particles on the damage threshold of laser-illuminated fused silica optics and set cleanliness requirements for optics on the beam line of the National Ignition Facility at Lawrence Livermore National Laboratory. Circular contamination particles were sputter-deposited onto fused silica windows which were then illuminated repetitively using a 1064nm laser. A variety of contaminants were tested including metals, oxides, and organics. Tests were conducted with particles on the input and output surfaces of the window, and the morphological features of the damage were very reproducible. A plasma often ignited at the contamination particle; its intensity was dependent upon the mass of the contaminant. Input surface damage was characteristically more severe than output surface damage. The size of the damaged area scaled with the size of the particle. On a few occasions, catastrophic damage (cracking or ablation of the substrate) initiated on the output surface due to contamination particles on either the input or output surface. From damage growth plots, predictions can be made about the severity of damage expected from contamination particles of known size and material.

  7. Invited article: CO2 laser production of fused silica fibers for use in interferometric gravitational wave detector mirror suspensions.

    PubMed

    Heptonstall, A; Barton, M A; Bell, A; Cagnoli, G; Cantley, C A; Crooks, D R M; Cumming, A; Grant, A; Hammond, G D; Harry, G M; Hough, J; Jones, R; Kelley, D; Kumar, R; Martin, I W; Robertson, N A; Rowan, S; Strain, K A; Tokmakov, K; van Veggel, M

    2011-01-01

    In 2000 the first mirror suspensions to use a quasi-monolithic final stage were installed at the GEO600 detector site outside Hannover, pioneering the use of fused silica suspension fibers in long baseline interferometric detectors to reduce suspension thermal noise. Since that time, development of the production methods of fused silica fibers has continued. We present here a review of a novel CO(2) laser-based fiber pulling machine developed for the production of fused silica suspensions for the next generation of interferometric gravitational wave detectors and for use in experiments requiring low thermal noise suspensions. We discuss tolerances, strengths, and thermal noise performance requirements for the next generation of gravitational wave detectors. Measurements made on fibers produced using this machine show a 0.8% variation in vertical stiffness and 0.05% tolerance on length, with average strengths exceeding 4 GPa, and mechanical dissipation which meets the requirements for Advanced LIGO thermal noise performance.

  8. Monitoring annealing via carbon dioxide laser heating of defect populations in fused silica surfaces using photoluminescence microscopy

    SciTech Connect

    Raman, R N; Matthews, M J; Adams, J J; Demos, S G

    2010-02-01

    Photoluminescence (PL) microscopy and spectroscopy under 266 nm and 355 nm laser excitation are explored as a means of monitoring defect populations in laser-modified sites on the surface of fused silica and their subsequent response to heating to different temperatures via exposure to a CO{sub 2} laser beam. Laser-induced temperature changes were estimated using an analytic solution to the heat flow equation and compared to changes in the PL emission intensity. The results indicate that the defect concentrations decrease significantly with increasing CO{sub 2} laser exposure and are nearly eliminated when the peak surface temperature exceeds the softening point of fused silica ({approx}1900K), suggesting that this method might be suitable for in situ monitoring of repair of defective sites in fused silica optical components.

  9. The effect of high-pressure devitrification and densification on ballistic-penetration resistance of fused silica

    NASA Astrophysics Data System (ADS)

    Avuthu, Vasudeva Reddy

    Despite the clear benefits offered by more advanced transparent materials, (e.g. transparent ceramics offer a very attractive combination of high stiffness and high hardness levels, highly-ductile transparent polymers provide superior fragment-containing capabilities, etc.), ballistic ceramic-glass like fused-silica remains an important constituent material in a majority of transparent impact-resistant structures (e.g. windshields and windows of military vehicles, portholes in ships, ground vehicles and spacecraft) used today. Among the main reasons for the wide-scale use of glass, the following three are most frequently cited: (i) glass-structure fabrication technologies enable the production of curved, large surface-area, transparent structures with thickness approaching several inches; (ii) relatively low material and manufacturing costs; and (iii) compositional modifications, chemical strengthening, and controlled crystallization have been demonstrated to be capable of significantly improving the ballistic properties of glass. In the present work, the potential of high-pressure devitrification and densification of fused-silica as a ballistic-resistance-enhancement mechanism is investigated computationally. In the first part of the present work, all-atom molecular-level computations are carried out to infer the dynamic response and material microstructure/topology changes of fused silica subjected to ballistic impact by a nanometer-sized hard projectile. The analysis was focused on the investigation of specific aspects of the dynamic response and of the microstructural changes such as the deformation of highly sheared and densified regions, and the conversion of amorphous fused silica to SiO2 crystalline allotropic modifications (in particular, alpha-quartz and stishovite). The microstructural changes in question were determined by carrying out a post-processing atom-coordination procedure. This procedure suggested the formation of high-density stishovite (and

  10. Correlation of Ge E' defect sites with second-harmonic generation in poled high-water fused silica

    NASA Astrophysics Data System (ADS)

    Henry, Leanne J.

    1995-08-01

    Second-harmonic generation (SHG) in poled high-water fused silica was found to be linearly dependent on the relative concentration of Ge E \\prime defect sites ( <10-15 defect sites/cm 3 ) for the highly pure UV-grade material. For commercial-grade material characterized by higher concentrations of Ge E\\prime defects sites, the SHG appeared to saturate at approximately 0.5 pm/V . No dependence of the SHG was found on the relative concentration of Ge E\\prime defects sites in poled commercial-grade low-water fused silica.

  11. Single-shot high aspect ratio bulk nanostructuring of fused silica using chirp-controlled ultrafast laser Bessel beams

    SciTech Connect

    Bhuyan, M. K.; Velpula, P. K.; Colombier, J. P.; Olivier, T.; Faure, N.; Stoian, R.

    2014-01-13

    We report single-shot, high aspect ratio nanovoid fabrication in bulk fused silica using zeroth order chirp-controlled ultrafast laser Bessel beams. We identify a unique laser pulse length and energy dependence of the physical characteristics of machined structures over which nanovoids of diameter in the range 200–400 nm and aspect ratios exceeding 1000 can be fabricated. A mechanism based on the axial energy deposition of nonlinear ultrashort Bessel beams and subsequent material densification or rarefaction in fused silica is proposed, intricating the non-diffractive nature with the diffusing character of laser-generated free carriers. Fluid flow through nanochannel is also demonstrated.

  12. Mitigation of Laser Damage Growth in Fused Silica with a Galvanometer Scanned CO2 Laser

    SciTech Connect

    Bass, I L; Guss, G M; Hackel, R P

    2005-10-28

    At the National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory (LLNL), mitigation of laser surface damage growth on fused silica using single and multiple CO{sub 2} laser pulses has been consistently successful for damage sites whose lateral dimensions are less than 100 {micro}m, but has not been for larger sites. Cracks would often radiate outward from the damage when a CO{sub 2} pulse was applied to the larger sites. An investigation was conducted to mitigate large surface damage sites using galvanometer scanning of a tightly focused CO{sub 2} laser spot over an area encompassing the laser damage. It was thought that by initially scanning the CO{sub 2} spot outside the damage site, radiating crack propagation would be inhibited. Scan patterns were typically inward moving spirals starting at radii somewhat larger than that of the damage site. The duration of the mitigation spiral pattern was {approx}110 ms during which a total of {approx}1.3 J of energy was delivered to the sample. The CO{sub 2} laser spot had a 1/e{sup 2}-diameter of {approx}200 {micro}m. Thus, there was general heating of a large area around the damage site while rapid evaporation occurred locally at the laser spot position in the spiral. A 30 to 40 {micro}m deep crater was typically generated by this spiral with a diameter of {approx}600 {micro}m. The spiral would be repeated until there was no evidence of the original damage in microscope images. Using this technique, damage sites as large as 300 mm in size did not display new damage after mitigation when exposed to fluences exceeding 22 J/cm{sup 2} at 355 nm, 7.5 ns. It was found necessary to use a vacuum nozzle during the mitigation process to reduce the amount of re-deposited fused silica. In addition, curing spiral patterns at lower laser powers were used to presumably ''re-melt'' any re-deposited fused silica. A compact, shearing interferometer microscope was developed to permit in situ measurement of the depth of

  13. Dental resin composites containing silica-fused whiskers--effects of whisker-to-silica ratio on fracture toughness and indentation properties.

    PubMed

    Xu, Hockin H K; Quinn, Janet B; Smith, Douglas T; Antonucci, Joseph M; Schumacher, Gary E; Eichmiller, Frederick C

    2002-02-01

    Dental resin composites need to be strengthened in order to improve their performance in large stress-bearing applications such as crowns and multiple-unit restorations. Recently, silica-fused ceramic whiskers were used to reinforce dental composites, and the whisker-to-silica ratio was found to be a key microstructural parameter that determined the composite strength. The aim of this study was to further investigate the effects of whisker-to-silica ratio on the fracture toughness, elastic modulus, hardness and brittleness of the composite. Silica particles and silicon carbide whiskers were mixed at whisker:silica mass ratios of 0:1, 1:5. 1:2, 1:1, 2:1, 5:1, and 1:0. Each mixture was thermally fused, silanized and combined with a dental resin at a filler mass percentage of 60%. Fracture toughness was measured with a single-edge notched beam method. Elastic modulus and hardness were measured with a nano-indentation system. Whisker:silica ratio had significant effects on composite properties. The composite toughness (mean+/-SD; n = 9) at whisker:silica = 2:1 was (2.47+/-0.28) MPa m(1/2), significantly higher than (1.02+/-0.23) at whisker:silica = 0:1, (1.13+/-0.19) of a prosthetic composite control, and (0.95+/-0.11) of an inlay/onlay composite control (Tukey's at family confidence coefficient = 0.95). Elastic modulus increased monotonically and hardness plateaued with increasing the whisker:silica ratio. Increasing the whisker:silica ratio also decreased the composite brittleness, which became about 1/3 of that of the inlay:onlay control. Electron microscopy revealed relatively flat fracture surfaces for the controls, but much rougher ones for the whisker composites, with fracture steps and whisker pullout contributing to toughness. The whiskers appeared to be well-bonded with the matrix, probably due to the fused silica producing rough whisker surfaces. Reinforcement with silica-fused whiskers resulted in novel dental composites that possessed fracture toughness

  14. Determination of diffusion coefficients of hydrogen in fused silica between 296 and 523 K by Raman spectroscopy and application of fused silica capillaries in studying redox reactions

    USGS Publications Warehouse

    Shang, L.; Chou, I.-Ming; Lu, W.; Burruss, R.C.; Zhang, Y.

    2009-01-01

    Diffusion coefficients (D) of hydrogen in fused silica capillaries (FSC) were determined between 296 and 523 K by Raman spectroscopy using CO2 as an internal standard. FSC capsules (3.25 ?? 10-4 m OD, 9.9 ?? 10-5 m ID, and ???0.01 m long) containing CO2 and H2 were prepared and the initial relative concentrations of hydrogen in these capsules were derived from the Raman peak-height ratios between H2 (near 587 cm-1) and CO2 (near 1387 cm-1). The sample capsules were then heated at a fixed temperature (T) at one atmosphere to let H2 diffuse out of the capsule, and the changes of hydrogen concentration were monitored by Raman spectroscopy after quench. This process was repeated using different heating durations at 296 (room T), 323, 375, 430, 473, and 523 K; the same sample capsule was used repeatedly at each temperature. The values of D (in m2 s-1) in FSC were obtained by fitting the observed changes of hydrogen concentration in the FSC capsule to an equation based on Fick's law. Our D values are in good agreement with the more recent of the two previously reported experimental data sets, and both can be represented by: ln D = - (16.471 ?? 0.035) - frac(44589 ?? 139, RT) (R2 = 0.99991) where R is the gas constant (8.3145 J/mol K), T in Kelvin, and errors at 1?? level. The slope corresponds to an activation energy of 44.59 ?? 0.14 kJ/mol. The D in FSC determined at 296 K is about an order of magnitude higher than that in platinum at 723 K, indicating that FSC is a suitable membrane for hydrogen at temperature between 673 K and room temperature, and has a great potential for studying redox reactions at these temperatures, especially for systems containing organic material and/or sulphur. ?? 2009 Elsevier Ltd.

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

    NASA Astrophysics Data System (ADS)

    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.

  16. Evaluation and analysis of polished fused silica subsurface quality by the nanoindenter technique

    SciTech Connect

    Ma Bin; Shen Zhengxiang; He Pengfei; Sha Fei; Wang Chunliang; Wang Bin; Ji Yiqin; Liu Huasong; Li Weihao; Wang Zhanshan

    2011-03-20

    We evaluate the subsurface quality of polished fused silica samples using the nanoindenter technique. Two kinds of samples, consisting of hundreds of nanometers and micrometers of subsurface damage layers, are fabricated by controlling the grinding and polishing processes, and the subsurface quality has been verified by the chemical etching method. Then several nanoindentation experiments are performed using the Berkovich tip to investigate the subsurface quality. Some differences are found by relative measurements in terms of the relationship between the total penetration and the peak load on the surfaces, the modulus calculated over the defined depths and from unload, and the indented morphology at a constant load near the surface collapse threshold. Finally, the capabilities of such a mechanical method for detecting subsurface flaws are discussed and analyzed.

  17. Reduction of damage initiation density in fused silica optics via UV laser conditioning

    DOEpatents

    Peterson, John E.; Maricle, Stephen M.; Brusasco, Raymond M.; Penetrante, Bernardino M.

    2004-03-16

    The present invention provides a method for reducing the density of sites on the surface of fused silica optics that are prone to the initiation of laser-induced damage, resulting in optics which have far fewer catastrophic defects and are better capable of resisting optical deterioration upon exposure for a long period of time to a high-power laser beam having a wavelength of about 360 nm or less. The initiation of laser-induced damage is reduced by conditioning the optic at low fluences below levels that normally lead to catastrophic growth of damage. When the optic is then irradiated at its high fluence design limit, the concentration of catastrophic damage sites that form on the surface of the optic is greatly reduced.

  18. Infrared Femtosecond Laser Direct-Writing Digital Volume Gratings in Fused Silica

    NASA Astrophysics Data System (ADS)

    Wang, Ying; Li, Yu-Hua; Lu, Pei-Xiang

    2010-04-01

    We demonstrate that digital volume gratings can be fabricated in fused silica glass conveniently by direct femtosecond laser writing. The diffraction efficiencies of volume gratings can be essentially modulated by simply stacking and offsetting the unit structure. A series of volume gratings, which have the pitches of 5 μm and the size of 1 mm × 1 mm, have been fabricated with the writing speed of 500 μm/s, with which the processing period of each grating layer could be reduced to several minutes with a 1-kHz femtosecond laser system. Results show that the power spectrum of the diffracted waves of the volume gratings are dependent on the layer gap and layer offsetting.

  19. Three-dimensional optical sensing network written in fused silica glass with femtosecond laser.

    PubMed

    Zhang, Haibin; Ho, Stephen; Eaton, Shane M; Li, Jianzhao; Herman, Peter R

    2008-09-01

    A single-step fast-writing method of burst ultrafast laser modification was applied to form a mesh network of multi-wavelength Bragg grating waveguides in bulk fused silica glass. Strain-optic and thermo-optic responses of the laser-written internal sensors are reported for the first time. A dual planar layout provided independent temperature- and strain-compensated characterization of temperature and strain distribution with coarse spatial resolution. The grating responses were thermally stable to 500 masculineC. To our best knowledge, the grating network represents the first demonstration of 3D distributed optical sensing network in a bulk transparent medium. Such 3D grating networks open new directions for strain and temperature sensing in optical circuits, optofluidic, MEMS or lab-on-a-chip microsystems, actuators, and windows and other large display or civil structures.

  20. Femtosecond laser microhole drilling inside a fused silica optical fiber with optical inner surface quality

    NASA Astrophysics Data System (ADS)

    Shiraishi, Masahiko; Goya, Kenji; Nishiyama, Michiko; Kubodera, Shoichi; Watanabe, Kazuhiro

    2016-09-01

    We have demonstrated femtosecond laser microhole drilling inside a fused silica optical fiber with optical inner surface quality. An optical quality microhole with a diameter of 3 μ m and a length of approximately 35 μ m was produced inside an optical fiber of a cladding diameter of 125 μ m. The microhole drilling inside an optical fiber was caused as a result of plasma filamentation of focused femtosecond laser irradiation at a wavelength of 400 nm. The size of the microhole was reproduced with a ray trace of the focused laser beam with consideration of self-focusing. The optical quality of the microhole was verified by measuring the transmittance of 94 % of infrared diode emission.

  1. Apparatus for dimensional characterization of fused silica fibers for the suspensions of advanced gravitational wave detectors.

    PubMed

    Cumming, A; Jones, R; Barton, M; Cagnoli, G; Cantley, C A; Crooks, D R M; Hammond, G D; Heptonstall, A; Hough, J; Rowan, S; Strain, K A

    2011-04-01

    Detection of gravitational waves from astrophysical sources remains one of the most challenging problems faced by experimental physicists. A significant limit to the sensitivity of future long-baseline interferometric gravitational wave detectors is thermal displacement noise of the test mass mirrors and their suspensions. Suspension thermal noise results from mechanical dissipation in the fused silica suspension fibers suspending the test mass mirrors and is therefore an important noise source at operating frequencies between ∼10 and 30 Hz. This dissipation occurs due to a combination of thermoelastic damping, surface and bulk losses. Its effects can be reduced by optimizing the thermoelastic and surface loss, and these parameters are a function of the cross sectional dimensions of the fiber along its length. This paper presents a new apparatus capable of high resolution measurements of the cross sectional dimensions of suspension fibers of both rectangular and circular cross section, suitable for use in advanced detector mirror suspensions.

  2. CO2-Laser Polishing for Reduction of 351-nm Surface Damage Initiation in Fused Silica

    SciTech Connect

    Brusasco, R M; Penetrante, B M; Butler, J A; Maricle, S M; Peterson, J E

    2001-11-01

    We have applied a carbon dioxide (CO{sub 2}) raster scanning laser polishing technique on two types of fused silica flat optics to determine the efficacy of CO{sub 2}-laser polishing as a method to increase the 351-nm laser damage resistance of optic surfaces. R-on-1 damage test results show that the fluence for any given 355-nm damage probability is 10-15 J/cm{sup 2} higher (at 3 ns pulse length, scaled) for the CO{sub 2}-laser polished samples. Poor quality and good quality surfaces respond to the treatment such that their surface damage resistance is brought to approximately the same level. Surface stress and the resultant effect on wavefront quality remain key technology issues that would need to be addressed for a robust deployment.

  3. Correlation of Laser-Induced Damage to Phase Objects in Bulk Fused Silica

    SciTech Connect

    Nostrand, M C; Cerjan, C J; Johnson, M A; Suratwala, T I; Weiland, T L; Sell, W D; Vickers, J L; Luthi, R L; Stanley, J R; Parham, T G; Thorsness, C B

    2004-11-10

    The Optical Sciences Laser (OSL) Upgrade facility, described in last year's proceedings, is a kJ-class, large aperture (100cm{sup 2}) laser system that can accommodate prototype optical components for large-scale inertial confinement fusion lasers. High-energy operation of such lasers is often limited by damage to the optical components. Recent experiments on the OSL Upgrade facility using fused silica components at 4 J/cm{sup 2} (351-nm, 3-ns) have created output surface and bulk damage sites that have been correlated to phase objects in the bulk of the material. Optical Path Difference (OPD) measurements of the phase defects indicate the probability of laser-induced damage is strongly dependent on OPD.

  4. Solventless determination of caffeine in beverages using solid-phase microextraction with fused-silica fibers.

    PubMed

    Hawthorne, S B; Miller, D J; Pawliszyn, J; Arthur, C L

    1992-06-19

    Caffeine concentrations in beverages were determined using a simple and rapid method based on microextraction of caffeine onto the surface of a fused-silica fiber. The uncoated fiber was dipped into the beverage sample for 5 min after the addition of isotopically labeled (trimethyl 13C)caffeine. The adsorbed caffeine was then thermally desorbed in a conventional split/splitless injection port, and the concentration of caffeine was determined using gas chromatography with mass spectrometric detection. Quantitative reproducibilities were ca. 5% (relative standard deviation) and the entire scheme including sample preparation and gas chromatographic analysis was completed in ca. 15 min per sample. The potential of the microextraction technique for the analysis of flavor and fragrance compounds in non-caffeinated beverages is also demonstrated. Since no solvents or class-fractionation steps are required, the method has good potential for automation.

  5. Fused Silica Final Optics for Inertial Fusion Energy: Radiation Studies and System-Level Analysis

    SciTech Connect

    Latkowski, Jeffery F.; Kubota, Alison; Caturla, Maria J.; Dixit, Sham N.; Speth, Joel A.; Payne, Stephen A.

    2003-06-15

    The survivability of the final optic, which must sit in the line of sight of high-energy neutrons and gamma rays, is a key issue for any laser-driven inertial fusion energy (IFE) concept. Previous work has concentrated on the use of reflective optics. Here, we introduce and analyze the use of a transmissive final optic for the IFE application. Our experimental work has been conducted at a range of doses and dose rates, including those comparable to the conditions at the IFE final optic. The experimental work, in conjunction with detailed analysis, suggests that a thin, fused silica Fresnel lens may be an attractive option when used at a wavelength of 351 nm. Our measurements and molecular dynamics simulations provide convincing evidence that the radiation damage, which leads to optical absorption, not only saturates but that a 'radiation annealing' effect is observed. A system-level description is provided, including Fresnel lens and phase plate designs.

  6. Dependence of growth rate of quartz in fused silica on pressure and impurity content

    NASA Technical Reports Server (NTRS)

    Fratello, V. J.; Hays, J. F.; Turnbull, D.

    1980-01-01

    The effects of pressure, temperature, and some variations in impurity content on the growth rate u of quartz into fused silica were measured. Under all conditions the growth rate was interface controlled and increased exponentially with pressure with an activation volume averaging -21.2 cu cm/mole. The activation enthalpy for all specimens is extrapolated to a zero pressure value of 64 kcal/mole, within the experimental uncertainty. At a given stoichiometry the effect of hydroxyl content on growth rate is described entirely by a linear term C(OH) in the prefactor of the equation for the growth rate. The effect of chlorine impurity can be described similarly. Also u is increased as the ideal stoichiometry is approached from the partially reduced state.

  7. Filamentation of an annular laser beam with a vortex phase dislocation in fused silica

    NASA Astrophysics Data System (ADS)

    Vasil'ev, E. V.; Shlenov, S. A.

    2016-11-01

    The filamentation of a femtosecond laser pulse in fused silica has been numerically investigated for the case of an annular beam with a phase singularity at a wavelength of 800 {\\text{nm}}. The spatiotemporal propagation dynamics of the pulse and the transformation of its frequency-angular spectra are analysed. It is shown that a tubular structure with a radius of 3 - 4 \\unicode{956}{\\text{m}}, peak intensity of about 2.4 × 1013 {\\text{W cm}}-2, and maximum plasma density on the order of 1020 {\\text{cm}}-3 is formed in the nonlinear focus; the length of this structure significantly exceeds the waist length in the linear case. The results of the analysis are compared with the data obtained for an annular beam free of phase dislocations and for a Gaussian beam.

  8. Disposable Polydimethylsiloxane (PDMS)-Coated Fused Silica Optical Fibers for Sampling Pheromones of Moths

    PubMed Central

    Lievers, Rik; Groot, Astrid T.

    2016-01-01

    In the past decades, the sex pheromone composition in female moths has been analyzed by different methods, ranging from volatile collections to gland extractions, which all have some disadvantage: volatile collections can generally only be conducted on (small) groups of females to detect the minor pheromone compounds, whereas gland extractions are destructive. Direct-contact SPME overcomes some of these disadvantages, but is expensive, the SPME fiber coating can be damaged due to repeated usage, and samples need to be analyzed relatively quickly after sampling. In this study, we assessed the suitability of cheap and disposable fused silica optical fibers coated with 100 μm polydimethylsiloxane (PDMS) by sampling the pheromone of two noctuid moths, Heliothis virescens and Heliothis subflexa. By rubbing the disposable PDMS fibers over the pheromone glands of females that had called for at least 15 minutes and subsequently extracting the PDMS fibers in hexane, we collected all known pheromone compounds, and we found a strong positive correlation for most pheromone compounds between the disposable PDMS fiber rubs and the corresponding gland extracts of the same females. When comparing this method to volatile collections and the corresponding gland extracts, we generally found comparable percentages between the three techniques, with some differences that likely stem from the chemical properties of the individual pheromone compounds. Hexane extraction of cheap, disposable, PDMS coated fused silica optical fibers allows for sampling large quantities of individual females in a short time, eliminates the need for immediate sample analysis, and enables to use the same sample for multiple chemical analyses. PMID:27533064

  9. Strong and bioactive composites containing nano-silica-fused whiskers for bone repair.

    PubMed

    Xu, Hockin H K; Smith, Douglas T; Simon, Carl G

    2004-08-01

    Self-hardening calcium phosphate cement (CPC) sets to form hydroxyapatite with high osteoconductivity, but its brittleness and low strength limit its use to only non-stress bearing locations. Previous studies developed bioactive composites containing hydroxyapatite fillers in Bis-GMA-based composites for bone repair applications, and they possessed higher strength values. However, these strengths were still lower than the strength of cortical bone. The aim of this study was to develop strong and bioactive composites by combining CPC fillers with nano-silica-fused whiskers in a resin matrix, and to characterize the mechanical properties and cell response. Silica particles were fused to silicon carbide whiskers to roughen the whisker surfaces for enhanced retention in the matrix. Mass ratios of whisker:CPC of 1:2, 1:1 and 2:1 were incorporated into a Bis-GMA-based resin and hardened by two-part chemical curing. Composite with only CPC fillers without whiskers served as a control. The specimens were tested using three-point flexure and nano-indentation. Composites with whisker:CPC ratios of 2:1 and 1:1 had flexural strengths (mean+/-SD; n=9) of (164+/-14) MPa and (139+/-22) MPa, respectively, nearly 3 times higher than (54+/-5) MPa of the control containing only CPC fillers (p<0.05). The strength of the new whisker-CPC composites was 3 times higher than the strength achieved in previous studies for conventional bioactive composites containing hydroxyapatite particles in Bis-GMA-based resins. The mechanical properties of the CPC-whisker composites nearly matched those of cortical bone and trabecular bone. Osteoblast-like cell adhesion, proliferation and viability were equivalent on the non-whisker control containing only CPC fillers, on the whisker composite at whisker:CPC of 1:1, and on the tissue culture polystyrene control, suggesting that the new CPC-whisker composite was non-cytotoxic.

  10. Ultrafast laser induced electronic and structural modifications in bulk fused silica

    NASA Astrophysics Data System (ADS)

    Mishchik, K.; D'Amico, C.; Velpula, P. K.; Mauclair, C.; Boukenter, A.; Ouerdane, Y.; Stoian, R.

    2013-10-01

    Ultrashort laser pulses can modify the inner structure of fused silica, generating refractive index changes varying from soft positive (type I) light guiding forms to negative (type II) values with void presence and anisotropic sub-wavelength modulation. We investigate electronic and structural material changes in the type I to type II transition via coherent and incoherent secondary light emission reflecting free carrier behavior and post-irradiation material relaxation in the index change patterns. Using phase contrast microscopy, photoluminescence, and Raman spectroscopy, we determine in a space-resolved manner defect formation, redistribution and spatial segregation, and glass network reorganization paths in conditions marking the changeover between type I and type II photoinscription regimes. We first show characteristic patterns of second harmonic generation in type I and type II traces, indicating the collective involvement of free carriers and polarization memory. Second, incoherent photoemission from resonantly and non-resonantly excited defect states reveals accumulation of non-bridging oxygen hole centers (NBOHCs) in positive index domains and oxygen deficiency centers (ODCs) with O2- ions segregation in void-like regions and in the nanostructured domains, reflecting the interaction strength. Complementary Raman investigations put into evidence signatures of the different environments where photo-chemical densification (bond rearrangements) and mechanical effects can be indicated. NBOHCs setting in before visible index changes serve as precursors for subsequent compaction build-up, indicating a scenario of cold, defect-assisted densification for the soft type I irradiation regime. Additionally, we observe hydrodynamic effects and severe bond-breaking in type II zones with indications of phase transition. These observations illuminate densification paths in fused silica in low power irradiation regimes, and equally in energetic ranges, characterized by

  11. Internal structure of the nanogratings generated inside bulk fused silica by ultrafast laser direct writing

    SciTech Connect

    Sharma, S. P.; Vilar, R.; Oliveira, V.; Herrero, P.

    2014-08-07

    The aim of the present work was to characterize the internal structure of nanogratings generated inside bulk fused silica by ultrafast laser processing and to study the influence of diluted hydrofluoric acid etching on their structure. The nanogratings were inscribed at a depth of 100 μm within fused silica wafers by a direct writing method, using 1030 nm radiation wavelength and the following processing parameters: E = 5 μJ, τ = 560 fs, f = 10 kHz, and v = 100 μm/s. The results achieved show that the laser-affected regions are elongated ellipsoids with a typical major diameter of about 30 μm and a minor diameter of about 6 μm. The nanogratings within these regions are composed of alternating nanoplanes of damaged and undamaged material, with an average periodicity of 351 ± 21 nm. The damaged nanoplanes contain nanopores randomly dispersed in a material containing a large density of defects. These nanopores present a roughly bimodal size distribution with average dimensions for each class of pores 65 ± 20 × 16 ± 8 × 69 ± 16 nm{sup 3} and 367 ± 239 × 16 ± 8 × 360 ± 194 nm{sup 3}, respectively. The number and size of the nanopores increases drastically when an hydrofluoric acid treatment is performed, leading to the coalescence of these voids into large planar discontinuities parallel to the nanoplanes. The preferential etching of the damaged material by the hydrofluoric acid solution, which is responsible for the pores growth and coalescence, confirms its high defect density.

  12. Effects of 3D microlens transfer into fused silica substrate by CF4/O2 dry etching

    NASA Astrophysics Data System (ADS)

    Grigaliūnas, Viktoras; Jucius, Dalius; Lazauskas, Algirdas; Andrulevičius, Mindaugas; Sakaliūnienė, Jolita; Abakevičienė, Brigita; Kopustinskas, Vitoldas; Smetona, Saulius; Tamulevičius, Sigitas

    2017-01-01

    Nowadays, 3D microoptical elements find a variety of applications from light emitting diodes and household appliances to precise medical endoscopes. Such elements, fabricated in a fused silica substrate by combining 3D e-beam patterning and dry etching, can be used as a mold for the high throughput replication in polymeric materials by UV nanoimprint technique. Flexible and precise control of 3D shape in the resist layer can be achieved by e-beam patterning, but it is also very important to know peculiarities of 3D pattern transfer from resist layer into the fused silica substrate. This paper reports on the effects of PMMA 3D microlens pattern transfer into fused silica substrate by CF4/O2 dry etching. It is demonstrated that etching rate ratio between PMMA and fused silica changes during plasma treatment. Thus, the resulting shape of transferred 3D profile is different from the shape in PMMA and this variation must be assessed during the design phase.

  13. Post-processing of fused silica and its effects on damage resistance to nanosecond pulsed UV lasers.

    PubMed

    Ye, Hui; Li, Yaguo; Zhang, Qinghua; Wang, Wei; Yuan, Zhigang; Wang, Jian; Xu, Qiao

    2016-04-10

    HF-based (hydrofluoric acid) chemical etching has been a widely accepted technique to improve the laser damage performance of fused silica optics and ensure high-power UV laser systems at designed fluence. Etching processes such as acid concentration, composition, material removal amount, and etching state (etching with additional acoustic power or not) may have a great impact on the laser-induced damage threshold (LIDT) of treated sample surfaces. In order to find out the effects of these factors, we utilized the Taguchi method to determine the etching conditions that are helpful in raising the LIDT. Our results show that the most influential factors are concentration of etchants and the material etched away from the viewpoint of damage performance of fused silica optics. In addition, the additional acoustic power (∼0.6  W·cm-2) may not benefit the etching rate and damage performance of fused silica. Moreover, the post-cleaning procedure of etched samples is also important in damage performances of fused silica optics. Different post-cleaning procedures were, thus, experiments on samples treated under the same etching conditions. It is found that the "spraying + rinsing + spraying" cleaning process is favorable to the removal of etching-induced deposits. Residuals on the etched surface are harmful to surface roughness and optical transmission as well as laser damage performance.

  14. Hydrolysis of polycarbonate in sub-critical water in fused silica capillary reactor with in situ Raman spectroscopy

    USGS Publications Warehouse

    Pan, Z.; Chou, I.-Ming; Burruss, R.C.

    2009-01-01

    The advantages of using fused silica capillary reactor (FSCR) instead of conventional autoclave for studying chemical reactions at elevated pressure and temperature conditions were demonstrated in this study, including the allowance for visual observation under a microscope and in situ Raman spectroscopic characterization of polycarbonate and coexisting phases during hydrolysis in subcritical water. ?? 2009 The Royal Society of Chemistry.

  15. Investigation of stress induced by CO2 laser processing of fused silica optics for laser damage growth mitigation.

    PubMed

    Gallais, Laurent; Cormont, Philippe; Rullier, Jean-Luc

    2009-12-21

    Laser damage mitigation' is a process developed to prevent the growth of nanosecond laser-initiated damage sites under successive irradiation. It consists of re-fusing the damage area with a CO2 laser. In this paper we investigate the stress field created around mitigated sites which could have an influence on the efficiency of the process. A numerical model of CO2 laser interaction with fused silica is developed. It takes into account laser energy absorption, heat transfer, thermally induced stress and birefringence. Residual stress near mitigated sites in fused silica samples is characterized with specific photoelastic methods and theoretical data are compared to experiments. The stress distribution and quantitative values of stress levels are obtained for sites treated with the CO2 laser in various conditions of energy deposition (beam size, pulse duration, incident power). The results provided evidence that the presence of birefringence/residual stress around the mitigated sites has an effect on their laser damage resistance.

  16. Laser smoothing of sub-micron grooves in hydroxyl-rich fused silica

    SciTech Connect

    Shen, N; Matthews, M J; Fair, J E; Britten, J A; Nguyen, H T; Cooke, D; Elhadj, S; Yang, S T

    2009-10-30

    Nano- to micrometer-sized surface defects on UV-grade fused silica surfaces are known to be effectively smoothed through the use of high-temperature localized CO{sub 2} laser heating, thereby enhancing optical properties. However, the details of the mass transport and the effect of hydroxyl content on the laser smoothing of defective silica at submicron length scales is still not completely understood. In this study, we examine the morphological evolution of sub-micron, dry-etched periodic surface structures on type II and type III SiO{sub 2} substrates under 10.6 {micro}m CO{sub 2} laser irradiation using atomic force microscopy (AFM). In-situ thermal imaging was used to map the transient temperature field across the heated region, allowing assessment of the T-dependent mass transport mechanisms under different laser-heating conditions. Computational fluid dynamics simulations correlated well with experimental results, and showed that for large effective capillary numbers (N{sub c} > 2), surface diffusion is negligible and smoothing is dictated by capillary action, despite the relatively small spatial scales studied here. Extracted viscosity values over 1700-2000K were higher than the predicted bulk values, but were consistent with the surface depletion of OH groups, which was confirmed using confocal Raman microscopy.

  17. CO2 laser microprocessing for laser damage growth mitigation of fused silica optics

    NASA Astrophysics Data System (ADS)

    Doualle, Thomas; Gallais, Laurent; Monneret, Serge; Bouillet, Stephane; Bourgeade, Antoine; Ameil, Christel; Lamaignère, Laurent; Cormont, Philippe

    2017-01-01

    We report on the development of a mitigation process to prevent the growth of UV nanosecond laser-initiated damage sites under successive irradiations of fused silica components. The developed process is based on fast microablation of silica as it has been proposed by Bass et al. [Bass et al., Proc. SPIE 7842, 784220 (2010)]. This is accomplished by the displacement of the CO2 laser spot with a fast galvanometer beam scanner to form a crater with a typical conical shape to mitigate large (millimetric) and deep (few hundred microns) damage sites. We present the developed experimental system and process for this application. Particularly, we detail and evaluate a method based on quantitative phase imaging to obtain fast and accurate three-dimensional topographies of the craters. The morphologies obtained through different processes are then studied. Mitigation of submillimetric nanosecond damage sites is demonstrated through different examples. Experimental and numerical studies of the downstream intensifications, resulting in cone formation on the surface, are presented to evaluate and minimize the downstream intensifications. Eventually, the laser damage test resistance of the mitigated sites is evaluated at 355, 2.5 ns, and we discuss on the efficiency of the process for our application.

  18. Laser-induced damage morphology in fused silica at 1064 nm in the nanosecond regime

    NASA Astrophysics Data System (ADS)

    Chambonneau, Maxime; Diaz, Romain; Duchateau, Guillaume; Grua, Pierre; Natoli, Jean-Yves; Rullier, Jean-Luc; Lamaignère, Laurent

    2014-10-01

    The morphology of laser-induced damage sites at the exit surface of fused silica is tightly correlated to the mode composition of the nanosecond laser pulses at 1064 nm. In the single longitudinal mode (SLM) configuration, a molten and fractured central zone is surrounded by a funnel-shaped surface modification. Ring patterns surround the damage sites when these are initiated by multiple longitudinal modes (MLM) laser pulses. In this last mode configuration, the pulses temporal profiles as well as the damage ring patterns differ from pulse to pulse. The appearance chronology of the rings is found to be closely related to the temporal shape of the laser pulses. This supports that the damage morphology originates from the coupling of a laser-supported detonation wave propagating in air with an ablation mechanism in silica. In our experiments, the propagation speed of the detonation wave reaches about 20 km/s and scales as the cube root of the laser intensity, in good agreement with theory.

  19. HF-based etching processes for improving laser damage resistance of fused silica optical surfaces

    SciTech Connect

    Suratwala, T I; Miller, P E; Bude, J D; Steele, R A; Shen, N; Monticelli, M V; Feit, M D; Laurence, T A; Norton, M A; Carr, C W; Wong, L L

    2010-02-23

    The effect of various HF-based etching processes on the laser damage resistance of scratched fused silica surfaces has been investigated. Conventionally polished and subsequently scratched fused silica plates were treated by submerging in various HF-based etchants (HF or NH{sub 4}F:HF at various ratios and concentrations) under different process conditions (e.g., agitation frequencies, etch times, rinse conditions, and environmental cleanliness). Subsequently, the laser damage resistance (at 351 or 355 nm) of the treated surface was measured. The laser damage resistance was found to be strongly process dependent and scaled inversely with scratch width. The etching process was optimized to remove or prevent the presence of identified precursors (chemical impurities, fracture surfaces, and silica-based redeposit) known to lead to laser damage initiation. The redeposit precursor was reduced (and hence the damage threshold was increased) by: (1) increasing the SiF{sub 6}{sup 2-} solubility through reduction in the NH4F concentration and impurity cation impurities, and (2) improving the mass transport of reaction product (SiF{sub 6}{sup 2-}) (using high frequency ultrasonic agitation and excessive spray rinsing) away from the etched surface. A 2D finite element crack-etching and rinsing mass transport model (incorporating diffusion and advection) was used to predict reaction product concentration. The predictions are consistent with the experimentally observed process trends. The laser damage thresholds also increased with etched amount (up to {approx}30 {micro}m), which has been attributed to: (1) etching through lateral cracks where there is poor acid penetration, and (2) increasing the crack opening resulting in increased mass transport rates. With the optimized etch process, laser damage resistance increased dramatically; the average threshold fluence for damage initiation for 30 {micro}m wide scratches increased from 7 to 41 J/cm{sup 2}, and the statistical

  20. Formation of periodic surface ripples under the action of pulsed carbon dioxide laser radiation on fused silica

    NASA Astrophysics Data System (ADS)

    Emel'Ianov, V. I.; Konov, V. I.; Tokarev, V. N.; Seminogov, V. N.

    1989-01-01

    Theoretical and experimental results on the formation of periodic surface ripples (PSR) on fused silica under the normal-incidence pulsed linearly-polarized light of a wavelength-tunable CO2 laser are reported. The dielectric permittivity of silica under conditions of PSR formation has been determined for the first time. Good agreement between theoretical and experimental results is achieved only if the complete theory of PSR is applied, taking into account electrodynamic and thermal processes along with growth rate calculations for capillary waves.

  1. Evaluation of the fused silica thermal conductivity by comparing infrared thermometry measurements with two-dimensional simulations

    SciTech Connect

    Combis, Patrick; Cormont, Philippe; Hebert, David; Robin, Lucile; Rullier, Jean-Luc; Gallais, Laurent

    2012-11-19

    A self-consistent approach is proposed to determine the temperature dependent thermal conductivity k(T) of fused silica, for a range of temperatures up to material evaporation using a CO{sub 2} laser irradiation. Calculation of the temperature of silica using a two-dimensional axi-symmetric code was linked step by step as the laser power was increased with experimental measurements using infrared thermography. We show that previously reported k(T) does not reproduce the temporal profile as well as our adaptive fit which shows that k(T) evolves with slope discontinuities at the annealing temperature and the softening temperature.

  2. Morphology and mechanisms of picosecond ablation of metal films on fused silica substrates

    NASA Astrophysics Data System (ADS)

    Bass, Isaac L.; Negres, Raluca A.; Stanion, Ken; Guss, Gabe; Keller, Wesley J.; Matthews, Manyalibo J.; Rubenchik, Alexander M.; Yoo, Jae Hyuck; Bude, Jeffrey D.

    2016-12-01

    The ablation of magnetron sputtered metal films on fused silica substrates by a 1053 nm, picosecond class laser was studied as part of a demonstration of its use for in-situ characterization of the laser spot under conditions commonly used at the sample plane for laser machining and damage studies. Film thicknesses were 60 and 120 nm. Depth profiles and SEM images of the ablation sites revealed several striking and unexpected features distinct from those typically observed for ablation of bulk metals. Very sharp thresholds were observed for both partial and complete ablation of the films. Partial film ablation was largely independent of laser fluence with a surface smoothness comparable to that of the unablated surface. Clear evidence of material displacement was seen at the boundary for complete film ablation. These features were common to a number of different metal films including Inconel on commercial neutral density filters, stainless steel, and aluminum. We will present data showing the morphology of the ablation sites on these films as well as a model of the possible physical mechanisms producing the unique features observed.

  3. Determination of laser damage initiation probability and growth on fused silica scratches

    SciTech Connect

    Norton, M A; Carr, C W; Cross, D A; Negres, R A; Bude, J D; Steele, W A; Monticelli, M V; Suratwala, T I

    2010-10-26

    Current methods for the manufacture of optical components inevitably leaves a variety of sub-surface imperfections including scratches of varying lengths and widths on even the finest finishes. It has recently been determined that these finishing imperfections are responsible for the majority of laser-induced damage for fluences typically used in ICF class lasers. We have developed methods of engineering subscale parts with a distribution of scratches mimicking those found on full scale fused silica parts. This much higher density of scratches provides a platform to measure low damage initiation probabilities sufficient to describe damage on large scale optics. In this work, damage probability per unit scratch length was characterized as a function of initial scratch width and post fabrication processing including acid-based etch mitigation processes. The susceptibility of damage initiation density along scratches was found to be strongly affected by the post etching material removal and initial scratch width. We have developed an automated processing procedure to document the damage initiations per width and per length of theses scratches. We show here how these tools can be employed to provide predictions of the performance of full size optics in laser systems operating at 351 nm. In addition we use these tools to measure the growth rate of a damage site initiated along a scratch and compare this to the growth measured on an isolated damage site.

  4. Material removal and surface figure during pad polishing of fused silica

    SciTech Connect

    Suratwala, T I; Feit, M D; Steele, W A

    2009-05-04

    The material removal and surface figure after ceria pad polishing of fused silica glass have been measured and analyzed as a function of kinematics, loading conditions, and polishing time. Also, the friction at the workpiece/lap interface, the slope of the workpiece relative to the lap plane, and lap viscoelastic properties have been measured and correlated to material removal. The results show that the relative velocity between the workpiece & lap (determined by the kinematics) and the pressure distribution determine the spatial and temporal material removal and hence the final surface figure of the workpiece. In the case where the applied loading and relative velocity distribution over the workpiece are spatially uniform, a significant non-uniform spatial material removal from the workpiece surface is observed. This is due to a non-uniform pressure distribution resulting from: (1) a moment caused by a pivot point and interface friction forces; (2) viscoelastic relaxation of the polyurethane lap; and (3) a physical workpiece/lap interface mismatch. Both the kinematics and these contributions to the pressure distribution are quantitatively described, and then combined to form a spatial and temporal Preston model & code for material removal (called Surface Figure or SurF{copyright}). The surface figure simulations are consistent with the experiment for a wide variety of polishing conditions. This study is an important step towards deterministic full-aperture polishing, which would allow optical glass fabrication to be performed in a more repeatable, less iterative, and hence more economical manner.

  5. Experimental study on 800 nm femtosecond laser ablation of fused silica in air and vacuum

    NASA Astrophysics Data System (ADS)

    Xu, Shi-zhen; Yao, Cai-zhen; Liao, Wei; Yuan, Xiao-dong; Wang, Tao; Zu, Xiao-tao

    2016-10-01

    Ablation rates of fused silica were studied as a function of femtosecond laser pulse fluences (0.7-41 J/cm2) in air and vacuum. The experiment was conducted by using a Ti:sapphire laser that emits radiation at 800 nm with a pulse width of 35 fs and a repetition rate of 10 Hz. The morphology and ablation depth of laser-induced damage crater were evaluated by using optical microscopy and scanning electron microscopy (SEM). Ablation rates were calculated from the depth of craters induced by multiple laser pulses. Results showed that two ablation regimes, i.e. non-thermal and thermal ablation co-existed in air and vacuum at low and moderate fluences. A drop of ablation rate was observed at high fluence (higher than 9.5 J/cm2) in air. While in vacuum, the ablation rate increased continuously with the increasing of laser fluence and much higher than that in air. The drop of ablation rate observed at high fluence in air was due to the strong defocusing effects associated with the non-equilibrium ionization of air. Furthermore, the laser-induced damage threshold (LIDT), which was determined from the relationship between crater area and the logarithm of laser energy, was found to depend on the number of incident pulses on the same spot, and similar phenomenon was observed in air and vacuum.

  6. Femtosecond laser-induced structural difference in fused silica with a non-reciprocal writing process

    NASA Astrophysics Data System (ADS)

    Song, Hui; Dai, Ye; Song, Juan; Ma, Hongliang; Yan, Xiaona; Ma, Guohong

    2017-04-01

    In this paper, we report a non-reciprocal writing process for inducing asymmetric microstructure using a femtosecond laser with tilted pulse fronts in fused silica. The shape of the induced microstructure at the focus closely depends on the laser scan direction. An elongated end is observed as a kind of structural difference between the written lines with two reverse scans along + x and - x, which further leads to a birefringence intensity difference. We also find a bifurcation in the head region of the induced microstructure between the written lines along x and y. That process results from the focal intensity distortion caused by the pulse front tilt by comparing the simulated intensity distribution with the experimental results. The current results demonstrate that the pulse front tilt not only affects the free electron excitation at the focus but also further distorts the shape of the induced microstructure during a high-energy femtosecond laser irradiation. These results offer a route to fabricate optical elements by changing the spatiotemporal characteristics of ultrashort pulses.

  7. Capillary isoelectric focusing of proteins and microorganisms in dynamically modified fused silica with UV detection.

    PubMed

    Horká, Marie; Růzicka, Filip; Horký, Jaroslav; Holá, Veronika; Slais, Karel

    2006-09-01

    We suggest a method for the reproducible and efficient capillary isoelectric focusing of proteins and microorganisms in the pH gradient 3-10. The method involves the segmental injection of the simple ampholytes, the solution of the selected electrolytes, and the sample mixture of bioanalytes and carrier ampholytes to the fused silica capillaries dynamically modified by poly(ethylene glycol), PEG 4000, which is added to the catholyte, the anolyte and injected solutions. In order to receive the reproducible results, the capillaries were rinsed by the mixture of acetone/ethanol between analyses. For the tracing of the pH gradients the low-molecular-mass pI markers were used. The simple proteins and the mixed cultures of microorganisms, Saccharomyces cerevisiae CCM 8191, Escherichia coli CCM 3954, Candida albicans CCM 8180, Candida parapsilosis, Candida krusei, Staphylococcus aureus, Streptococcus agalactiae CCM 6187, Enterococcus faecalis CCM 4224, Staphylococcus epidermidis CCM 4418 and Stenotrophomonas maltophilia, were focused and separated by the method suggested. The minimum detectable number of microbial cells was 5x10(2) to 1x10(3) with on-column UV detection at 280 nm.

  8. Dynamics of femtosecond laser absorption of fused silica in the ablation regime

    SciTech Connect

    Lebugle, M. Sanner, N.; Varkentina, N.; Sentis, M.; Utéza, O.

    2014-08-14

    We investigate the ultrafast absorption dynamics of fused silica irradiated by a single 500 fs laser pulse in the context of micromachining applications. A 60-fs-resolution pump-probe experiment that measures the reflectivity and transmissivity of the target under excitation is developed to reveal the evolution of plasma absorption. Above the ablation threshold, an overcritical plasma with highly non-equilibrium conditions is evidenced in a thin layer at the surface. The maximum electron density is reached at a delay of 0.5 ps after the peak of the pump pulse, which is a strong indication of the occurrence of electronic avalanche. The results are further analyzed to determine the actual feedback of the evolution of the optical properties of the material on the pump pulse. We introduce an important new quantity, namely, the duration of absorption of the laser by the created plasma, corresponding to the actual timespan of laser absorption by inverse Bremsstrahlung. Our results indicate an increasing contribution of plasma absorption to the total material absorption upon raising the excitation fluence above the ablation threshold. The role of transient optical properties during the energy deposition stage is characterized and our results emphasize the necessity to take it into account for better understanding and control of femtosecond laser-dielectrics interaction.

  9. In situ diagnostics of pulse laser-induced defects in DUV transparent fused silica glasses

    NASA Astrophysics Data System (ADS)

    Mühlig, Ch.; Triebel, W.; Bark-Zollmann, S.; Grebner, D.

    2000-05-01

    Excimer laser pulses (λ=248 or 193 nm) induce transient and permanent defects in optical glasses of high UV transparency. Such defects are causing additional absorption and changes of density and refractive index, respectively (compaction). The interaction of each laser pulse with different OH-rich fused silica samples was investigated by real time measurements of laser-induced fluorescence (LIF) and of Raman spectra excited by the 248 nm KrF-excimer laser. The irradiation of the glasses with energy densities of about 10 mJ/cm2 and more induces E‧ and NBOH defects simultaneously. The laser-induced fluorescence of NBOH defect centres at 650 nm characterises the kinetics of defect generation and relaxation. The primary absorption process is the two-photon absorption of KrF laser pulses. The relaxation of defects in the time interval between the laser pulses is mainly influenced by diffusion limited processes. Locally resolved LIF and Raman spectra allow the investigation of homogeneity and laser damage stability in large area substrates (e.g. for mask blanks). Raman spectra excited by KrF laser pulses are measured to detect precursors and intermediates of laser-induced defects and molecular hydrogen in the glass matrix. The detection limit of H2 molecules is in the range of 1017 cm-3. A correlation between LIF intensities and H2 concentrations is found.

  10. Comprehensive modeling of structural modification induced by a femtosecond laser pulse inside fused silica glass

    NASA Astrophysics Data System (ADS)

    Najafi, Somayeh; Sadat Arabanian, Atoosa; Massudi, Reza

    2016-06-01

    A comprehensive theoretical model is proposed based on equations describing the nonlinear propagation of an ultrashort pulse inside transparent material, electron density evolution, non-Fourier heat conduction, and thermo-elasto plastic displacement which are respectively solved by various methods. These methods include the split-step finite difference technique and alternating-direction implicit algorithm, fourth-order Range-Kutta algorithm, hybrid finite-element method/finite-difference method, and finite-element method in both space and time to achieve refractive index changes. The whole chain of processes occurring in the interaction of a focused ultrashort laser pulse with fused silica glass in prevalent conditions of micromachining applications is numerically investigated. By optimizing the numerical method and by using an adaptive mesh approach, the execution time of the program is significantly reduced so that the calculations are done at each time step in a fraction of a second. Simulation results show that the energy and duration of the input pulse are very important parameters in induced changes, but the chirp of the input pulse is not an effective parameter. Consequently, by appropriate setting of those parameters one can design a desired refractive index profile.

  11. Effect of a Silicone Contaminant Film on the Transmittance Properties of AR-coated Fused Silica

    NASA Technical Reports Server (NTRS)

    Boeder, Paul A.; Visentine, James T.; Shaw, Christopher G.; Carniglia, Charles K.; Ledbury, Eugene A.; Alred, John W.; Soares, Carlos E.

    2004-01-01

    We present the results of a laboratory test to determine the effects of bulk deposited, DC-704 silicone contaminant film on the transmittance properties of an anti-reflective (AR) coated fused silica optical substrate. Testing and optical measurements were performed in vacuum in the Boeing Combined Effects Test Facility (CETF). The test and measurement procedures are described herein. Measurement results are presented showing the change in transmittance characteristics as a function of contaminant deposit thickness and vacuum ultra-violet (vuv) exposure levels. Measurement results show an initial degradation in the transmittance of the contaminated sample. This is followed by a partial recovery in sample transmittance as the sample is exposed to additional VUV radiation. Transmittance results also show a loss of transmission in the ultraviolet portion of the spectrum and an increase in transmission in the infrared portion of the spectrum. These transmittance results are characteristic of thin-film interference effects. Thin-film analyses indicate that some of the observed transmittance results can be successfully modeled, but only if the contaminant film is assumed to be SiO2 rather than DC-704 silicone. Post-test Scanning Electron Microscope (SEM) scans of the test sample indicate the formation of contaminant islands and the presence of a thin uniform coating of contaminant deposit on the sample

  12. Generation of microstripe cylindrical and toroidal mirrors by localized laser evaporation of fused silica.

    PubMed

    Wlodarczyk, Krystian L; Thomson, Ian J; Baker, Howard J; Hall, Denis R

    2012-09-10

    We report a new technique for the rapid fabrication of microstripe cylindrical and toroidal mirrors with a high ratio (>10) of the two principal radii of curvature (RoC(1)/RoC(2)), and demonstrate their effectiveness as mode-selecting resonator mirrors for high-power planar waveguide lasers. In this process, the larger radius of curvature (RoC(1)) is determined by the planar or cylindrical shape of the fused silica substrate selected for laser processing, whilst the other (RoC(2)) is produced by controlled CO(2) laser-induced vaporization of the glass. The narrow stripe mirror aperture is achieved by applying a set of partially overlapped laser scans, with the incident laser power, the number of laser scans, and their spacing being used to control the curvature produced by laser evaporation. In this work, a 1 mm diameter laser spot is used to produce grooves of cylindrical/toroidal shape with 240 μm width and 16 mm length. After high reflectance coating, these grooves are found to provide excellent mode selectivity as resonator mirrors for a 150 μm core Yb:YAG planar waveguide laser, producing high brightness output at more than 300 W. The results show clearly that the laser-generated microstripe mirrors can improve the optical performance of high-power planar waveguide lasers when applied in a low-loss mode-selective resonator configuration.

  13. Spherical fused silica cells filled with pure helium for nuclear magnetic resonance-magnetometry

    SciTech Connect

    Maul, Andreas; Blümler, Peter Heil, Werner; Nikiel, Anna; Otten, Ernst; Petrich, Andreas; Schmidt, Thomas

    2016-01-15

    High magnetic fields (>1 T) are measured by NMR magnetometers with unrivaled precision if the precessing spin sample provides long coherence times. The longest coherence times are found in diluted {sup 3}He samples, which can be hyperpolarized for sufficient signal strength. In order to have minimal influence on the homogeneity and value of the measured magnetic field, the optimal container for the {sup 3}He should be a perfect sphere. A fused silica sphere with an inner diameter of 8 mm and an outer diameter of 12 mm was made from two hemispheres by diffusion bonding leaving only a small hole for cleaning and evacuation. This hole was closed in vacuum by a CO{sub 2} laser and the inner volume was filled with a few mbars of {sup 3}He via wall permeation. NMR-measurements on such a sample had coherence times of 5 min. While the hemispheres were produced with <1 μm deviation from sphericity, the bonding left a step of ca. 50 μm at maximum. The influence of such a mismatch, its orientation, and the immediate environment of the sample is analyzed by FEM-simulations and discussed in view of coherence times and absolute field measurements.

  14. Localized CO2 Laser Treatment for Mitigation of 3(omega) Damage Growth in Fused Silica

    SciTech Connect

    Brusasco, R M; Penetrante, B M; Butler, J A; Hrubesh, L W

    2001-12-07

    A technique for inhibiting the growth of laser-induced surface damage on fused silica, initiated and propagated at the 351 nm laser wavelength, has been investigated. The technique exposes the damage sites to single pulses of a CO{sub 2} laser operating at the 10.6 {micro}m wavelength at or near beam focus. This method results in a very localized treatment of the laser damage site and modifies the site such that laser damage does not propagate further. A laser damage site initiated with a single pulse of 355 nm laser light at {approx} 45 J cm{sup -2} and 7.5 ns pulse duration grows rapidly upon further illumination at 8 J cm{sup -2} with 100% probability. Treatment of these sites with single pulses of 10.6 {micro}m laser light for one second at a power level of between 17 and 37 Watts with a beam diameter of 5 mm alters the damage site such that it does not grow with subsequent 351 nm laser illumination at 8 J cm{sup -2} 10 ns pulse duration for > 1000 shots. The technique has been found to be 100% effective at stopping the growth of the laser damage.

  15. Influence of secondary treatment with CO2 laser irradiation for mitigation site on fused silica surface

    NASA Astrophysics Data System (ADS)

    Jiang, Yong; Zhou, Qiang; Qiu, Rong; Gao, Xiang; Wang, Hui-Li; Yao, Cai-Zhen; Wang, Jun-Bo; Zhao, Xin; Liu, Chun-Ming; Xiang, Xia; Zu, Xiao-Tao; Yuan, Xiao-Dong; Miao, Xin-Xiang

    2016-10-01

    The ablation debris and raised rim, as well as residual stress and deep crater will be formed during the mitigation of damage site with a CO2 laser irradiation on fused silica surface, which greatly affects the laser damage resistance of optics. In this study, the experimental study combined with numerical simulation is utilized to investigate the effect of the secondary treatment on a mitigated site by CO2 laser irradiation. The results indicate that the ablation debris and the raised rim can be completely eliminated and the depth of crater can be reduced. Notable results show that the residual stress of the mitigation site after treatment will reduce two-thirds of the original stress. Finally, the elimination and the controlling mechanism of secondary treatment on the debris and raised rim, as well as the reasons for changing the profile and stress are analyzed. The results can provide a reference for the optimization treatment of mitigation sites by CO2 laser secondary treatment. Project supported by the National Natural Science Foundation of China (Grant Nos. 61505170, 61505171, and 51535003), the Joint Fund of the National Natural Science Foundation of China, the Chinese Academy of Engineering Physics (Grant No. U1530109), and the China Postdoctoral Science Foundation (Grant No. 2016M592709).

  16. Linear and nonlinear optical response of bismuth and antimony implanted fused silica: annealing effects

    NASA Astrophysics Data System (ADS)

    Pan, Z.; Morgan, S. H.; Henderson, D. O.; Park, S. Y.; Weeks, R. A.; Magruder, R. H.; Zuhr, R. A.

    1995-10-01

    We report the linear and nonlinear optical response of bismuth and antimony implanted fused silica with doses of 6 × 10 16 ions/cm 2. The nonlinear refractive index, n2, was measured using a Z-scan technique with a mode locked Ti:sapphire laser operating in 140 fs pulse duration at 770 nm wavelength. It is found that the nonlinear refractive index n2 of as-implanted samples is large, in the order of 10 -10 cm 2/W and the n2 value of Bi as-implanted sample is about 2.4 times lager than that of Sb as-implanted sample. The large n2 response is attributed to the presence of nanosized metal particles in the implanted layer observed by transmission electron microscopy. We also report the changes of linear and nonlinear optical response when implanted samples were subsequently annealed at temperatures from 500 to 1000 C in argon and oxygen atmospheres. The annealing effect on optical properties is found to be strongly dependent on the annealing atmospheres. Our results indicate that annealing treatment in O 2 affects the local environment of the implanted metal ions and hence the linear and nonlinear optical properties of the metal-dielectric composite. We suggest that a new phase of metal-oxygen-silicate was formed during annealing in O 2 atmosphere.

  17. Low-loss Type II waveguide writing in fused silica with single picosecond laser pulses.

    PubMed

    Zhang, Haibin; Eaton, Shane M; Herman, Peter R

    2006-05-29

    A new domain of rapid waveguide writing with non-overlapping pulses of a 1-kHz ultrashort laser is demonstrated to produce low loss waveguides in fused silica glass. This new regime is distinguishable in two ways from traditional approaches in laser waveguide writing. First, an examination of a wide 50-fs to 5-ps range of pulse duration shows the lowest loss waveguides to form in a narrow 1.0 +/- 0.2 ps window that significantly exceeds the 50 - 200 fs duration reported as optimal in other studies. Second, an unusually high scan speed of 1.0 +/- 0.2 mm/s points to a novel Type-II photosensitivity mechanism for generating low-loss refractive index structures. The waveguides comprise of an array of nearly isolated single-pulse interaction volumes that sharply contrast with the high exposures of tens to thousands of overlapping laser pulses typically applied along a slowly moving focal volume. A minimum propagation loss of ~0.2 dB/cm and a slightly asymmetric mode diameter of ~9 mum is reported for 633-nm light. The low loss waveguides fabricated with picosecond pulses enables 3-D photonics circuit fabrication with simpler and lower cost picosecond laser systems.

  18. Fracture Strength of Fused Silica From Photonic Signatures Around Collision Sites

    NASA Technical Reports Server (NTRS)

    Yost, William T.; Cramer, K Elliott

    2015-01-01

    Impact sites in glass affect its fracture strength. An analytical model that predicts fracture strength from grey-field polariscope (GFP) readings (photoelastic retardations) has been developed and reported in the literature. The model is suggestive that stress fields, resulting from impact damage, destablizes sites within the glass, which lead to pathways that cause strength degradation. Using data collected from fused silica specimens fabricated from outer window panes that were designed for the space shuttle, the model was tested against four categories of inflicted damage. The damage sites were cored from the window carcasses, examined with the GFP and broken using the ASTM Standard C1499-09 to measure the fracture strength. A correlation is made between the fracture strength and the photoelastic retardation measured at the damage site in each specimen. A least-squares fit is calculated. The results are compared with the predictions from the model. A plausible single-sided NDE damage site inspection method (a version of which is planned for glass inspection in the Orion Project) that relates photoelastic retardation in glass components to its fracture strength is presented.

  19. Examination of Relationship Between Photonic Signatures and Fracture Strength of Fused Silica Used in Orbiter Windows

    NASA Technical Reports Server (NTRS)

    Yost, William T.; Cramer, K. Elliott; Estes, Linda R.; Salem, Jonathan A.; Lankford, James, Jr.; Lesniak, Jon

    2011-01-01

    A commercially available grey-field polariscope (GFP) instrument for photoelastic examination is used to assess impact damage inflicted upon the outermost pane of the orbiter windows. Four categories of damage: hyper-velocity impacts that occur during space-flight (HVI); hypervelocity impacts artificially made at the Hypervelocity Impact Technology Facility (HIT-F); impacts made by larger objects falling onto the pane surface to simulate dropped items on the window during service/storage of vehicle (Bruises); and light scratches from dull objects designed to mimic those that might occur by dragging a dull object across the glass surface (Chatter Checks) are examined. The damage sites are cored from fused silica window carcasses, examined with the GFP and other methodologies, and broken using the ASTM Standard C1499-09 to measure the fracture strength. A correlation is made between the fracture strength and damage-site measurements including geometrical measurements and GFP measurements of photoelastic retardation (stress patterns) surrounding the damage sites. An analytical damage model to predict fracture strength from photoelastic retardation measurements is presented and compared with experimental results.

  20. Filamentation and damage in fused silica induced by tightly focused femtosecond laser pulses

    SciTech Connect

    Couairon, A.; Sudrie, L.; Franco, M.; Prade, B.; Mysyrowicz, A.

    2005-03-15

    We investigate experimentally and numerically the damage tracks induced by tightly focused (NA=0.5) infrared femtosecond laser pulses in the bulk of a fused silica sample. Two types of irreversible damage are observed. The first damage corresponds to a permanent change of refractive index without structural modifications (type I). It appears for input pulse energies beyond 0.1 {mu}J. It takes the form of a narrow track extending over more than 100 {mu}m at higher input powers. It is attributed to a change of the polarizability of the medium, following a filamentary propagation which generates an electron-hole plasma through optical field ionization. A second type of damage occurs for input pulse energies beyond 0.3 {mu}J (type II). It takes the form of a pear-shaped structural damage associated with an electron-ion plasma triggered by avalanche. The temporal evolution of plasma absorption is studied by pump-probe experiments. For type I damage, a fast electron-hole recombination is observed. Type II damage is linked with a longer absorption.

  1. Temperature-dependent Absolute Refractive Index Measurements of Synthetic Fused Silica

    NASA Technical Reports Server (NTRS)

    Leviton, Douglas B.; Frey, Bradley J.

    2006-01-01

    Using the Cryogenic, High-Accuracy Refraction Measuring System (CHARMS) at NASA's Goddard Space Flight Center, we have measured the absolute refractive index of five specimens taken from a very large boule of Corning 7980 fused silica from temperatures ranging from 30 to 310 K at wavelengths from 0.4 to 2.6 microns with an absolute uncertainty of plus or minus 1 x 10 (exp -5). Statistical variations in derived values of the thermo-optic coefficient (dn/dT) are at the plus or minus 2 x 10 (exp -8)/K level. Graphical and tabulated data for absolute refractive index, dispersion, and thermo-optic coefficient are presented for selected wavelengths and temperatures along with estimates of uncertainty in index. Coefficients for temperature-dependent Sellmeier fits of measured refractive index are also presented to allow accurate interpolation of index to other wavelengths and temperatures. We compare our results to those from an independent investigation (which used an interferometric technique for measuring index changes as a function of temperature) whose samples were prepared from the same slugs of material from which our prisms were prepared in support of the Kepler mission. We also compare our results with sparse cryogenic index data from measurements of this material from the literature.

  2. Stable structure and optical properties of fused silica with NBOHC-E‧ defect

    NASA Astrophysics Data System (ADS)

    Lu, Peng-Fei; Wu, Li-Yuan; Yang, Yang; Wang, Wei-Zheng; Zhang, Chun-Fang; Yang, Chuang-Hua; Su, Rui; Chen, Jun

    2016-08-01

    First-principles method is used to simulate the stable structure and optical properties of a 96-atom fused silica. The preferable structure of NBOHC-E‧ (non-bridging oxygen hole center (NBOHC) and E‧ center) pair defect is predicted to be located at 2.4 Å for the Si-O bond length. The quasi-particle G0W0 calculations are performed and an accurate band gap is obtained in order to calculate the optical absorption properties. With the stretching of the Si1-O1 bond, an obvious redshift can be observed in the absorption spectrum. In the case of NBOHC-E‧ pair, the p-orbital DOS of Si1 atom will shift to the conduction band. Two obvious absorption peaks can be observed in the absorption spectrum. The calculation reproduced the peak positions of the well-known optical absorption bands. Project supported by the National Basic Research Program of China (Grant No. 2014CB643900), the Open Fund of IPOC (BUPT), the Open Program of State Key Laboratory of Functional Materials for Informatics, the National Natural Science Foundation for Theoretical Physics Special Fund “Cooperation Program” (Grant No. 11547039), and Shaanxi Provincial Institute of Scientific Research Plan Projects, China (Grant No. SLGKYQD2-05).

  3. Disordered antireflective subwavelength structures using Ag nanoparticles on fused silica windows.

    PubMed

    Shang, Peng; Xiong, Sheng Ming; Deng, Qi Ling; Shi, Li Fang; Zhang, Mian

    2014-10-10

    In this paper, we have demonstrated an effective method for fabricating disordered subwavelength structures (d-SWSs) on fused silica using thermal dewetted Ag nanoparticles at lower temperatures (<300°C) with a vacuum. Theoretically and experimentally, we investigate the effects of the film thickness, annealing temperature, and etching time on the antireflective properties of the d-SWS arrays. The measured data and calculated results obtained by rigorous coupled-wave analysis exhibit reasonably similar tendencies. For the sample with a 10-nm-thick Ag film, good optical transmission characteristics (on one side, T(ave)∼95.6%) over a wide wavelength region of 500-1300 nm were obtained, and a maximum value of ∼96% at a wavelength of 850 nm was also obtained. Furthermore, the d-SWSs exhibit excellent optical and thermal stability at high temperatures of 800°C and 1000°C compared to a conventional Ta2O5/SiO2 multilayer coating.

  4. Nanofracture on fused silica microchannel for Donnan exclusion based electrokinetic stacking of biomolecules.

    PubMed

    Wu, Zhi-Yong; Li, Cui-Ye; Guo, Xiao-Li; Li, Bo; Zhang, Da-Wei; Xu, Ye; Fang, Fang

    2012-09-21

    Due to Donnan exclusion, charged molecules are prohibited from passing through a channel of electrical double layer scale (nanometers), even though the molecules are smaller than the lowest dimension of the channel. To employ this effect for on-chip pre-concentration, an ion channel of nanometer scale has to be introduced. Here we introduced a simple method of generating a fracture (11-250 nm) directly on the commercially available open tubular fused silica capillary, and a chip comprised of the capillary with the nanofracture was prepared. A ring-disk model of the fracture was derived with which the fracture width can be easily characterized online without any damage to the chip, and the result was validated by a scanning electron microscope (SEM). The fractures can be used directly as a nanofluidic interface exhibiting an obvious ion concentration polarization effect with high current flux. On-chip electrokinetic stacking of SYBR Green I labeled λDNA inside the capillary was successfully demonstrated, and a concentration factor close to the amplification rate of the polymerase chain reaction (PCR) was achieved within 7 min. The chip is inexpensive and easy to prepare in common chemistry and biochemistry laboratories without limitations in expensive microfabrication facilities and sophisticated expertise. More applications of this interface could be found for enhancing the detectability of capillary based microfluidic analytical systems for the analysis of low concentrated charged species.

  5. Observation of inner surface roughness in fused silica microholes with varying the number of femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Shiraishi, Masahiko; Watanabe, Kazuhiro; Kubodera, Shoichi

    2017-01-01

    Inner walls of microhole in a thin fused silica plate were observed after changing ablating laser pulse shots of a focused femtosecond laser at the wavelength of 400 nm with an energy of 20 μJ in a pulse width of 350 fs. Using an objective lens with an NA of 0.28, it was revealed that the inner surface of the microhole was melted with 10 laser pulse shots. By increasing the pulse numbers to 100, however, deposition of fused silica particles on the melted inner surface was observed. In order to minimize the inner surface roughness, the objective lens was changed. After 50 laser pulse shots, the inner surface structure was brought close to optical quality using an objective lens with NA of 0.65.

  6. An AC phase measuring interferometer for measuring dn/dT of fused silica and calcium fluoride at 193 nm

    SciTech Connect

    Shagam, R.N.

    1998-09-01

    A novel method for the measurement of the change in index of refraction vs. temperature (dn/dT) of fused silica and calcium fluoride at the 193 nm wavelength has been developed in support of thermal modeling efforts for the development of 193 nm-based photolithographic exposure tools. The method, based upon grating lateral shear interferometry, uses a transmissive linear grating to divide a 193 nm laser beam into several beam paths by diffraction which propagate through separate identical material samples. One diffracted order passing through one sample overlaps the undiffracted beam from a second sample and forms interference fringes dependent upon the optical path difference between the two samples. Optical phase delay due to an index change from heating one of the samples causes the interference fringes to change sinusoidally with phase. The interferometer also makes use of AC phase measurement techniques through lateral translation of the grating. Results for several samples of fused silica and calcium fluoride are demonstrated.

  7. Femtosecond laser processing of fused silica and aluminum based on electron dynamics control by shaping pulse trains

    NASA Astrophysics Data System (ADS)

    Leng, Ni; Jiang, Lan; Li, Xin; Xu, Chuancai; Liu, Pengjun; Lu, Yongfeng

    2012-11-01

    The pulse train effects on femtosecond laser material processing are investigated from the viewpoint of electron dynamics on dielectrics with fused silica as a case study and metals with Al as a case study in air and water. During femtosecond laser (800 nm, 35 fs) pulse train (double pulses per train) processing of fused silica, a non-monotonic relationship between ablation size and pulse separation is observed with an abrupt rise in the range of 150-275 fs. It is assumed that this is due to the enhancement of photon-electron coupling efficiency and transition of the phase-change mechanism by adjusting the free electron density during pulse train ablation. Surface quality in Al is improved with less recast by designing the pulse energy distribution to adjust the electron/lattice temperature distribution. Furthermore, the positive effects on ablation quality by femtosecond pulse train technology are more significant in water than those in air.

  8. Molecular-Level Analysis of Shock-Wave Physics and Derivation of the Hugoniot Relations for Fused Silica

    DTIC Science & Technology

    2012-06-01

    suggested that irreversible non-equilibrium deformation/damage processes play an important role in the mechanical response of fused silica to shock loading...approaches are greatly affected by the fidelity of M. Grujicic, B. Pandurangan, Z. Zhang, and W.C. Bell, Department of Mechanical Engineering, Clemson...7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Clemson University,Department of Mechanical Engineering,241 Engineering Innovation Building

  9. Optical absorption in fused silica at elevated temperatures during 1.5-MeV electron irradiation

    NASA Technical Reports Server (NTRS)

    Smith, A. B.

    1972-01-01

    An experimental determination of the optical transmission of Corning 7940 UV and Suprasil 1 and 2 fused silica has been made during 1.5-MeV electron bombardment. The fused silica reached temperatures ranging from 150 to 1000 C. The Lewis Research Center dynamitron provided electron current densities which corresponded to a dose rate of 2.6 to 20 Mrad/sec. The irradiation induced absorption was measured at 215.0, 270.0, and 450.0 nm (2150, 2700, 4500 A). The length of each irradiation was sufficient so that an equilibrium between radiation induced coloration and high temperature annealing was reached. The experimental results indicate a significant optical absorption, with values of the induced absorption coefficient at 215.0 nm (2150 A) of 14.5 to 2.2/cm, at 270.0 nm (2700 A) of 9.7 to 3.0/cm and at 450.0 nm (4500 A) of 3.7 to 0.5/cm. This would make the use of fused silica as the separating wall material in the nuclear light bulb propulsion concept questionable.

  10. Study of the effects of polishing, etching, cleaving, and water leaching on the UV laser damage of fused silica

    SciTech Connect

    Yoshiyama, J.; Genin, F.Y.; Salleo, A.; Thomas, I.; Kozlowski, M.R.; Sheehan, L.M.; Hutcheon, I.D.; Camp, D.W.

    1997-12-23

    A damage morphology study was performed with a 355 nm Nd:YAG laser on synthetic UV-grade fused silica to determine the effects of post- polish chemical etching on laser-induced damage, compare damage morphologies of cleaved and polished surfaces, and understand the effects of the hydrolyzed surface layer and waste-crack interactions. The samples were polished , then chemically etched in buffered HF solution to remove 45,90,135, and 180 nm of surface material. Another set of samples was cleaved and soaked in boiling distilled water for 1 second and 1 hour. All the samples were irradiated at damaging fluencies and characterized by Normarski optical microscopy and scanning electron microscopy. Damage was initiated as micro-pits on both input and output surfaces of the polished fused silica sample. At higher fluencies, the micro-pits generated cracks on the surface. Laser damage of the polished surface showed significant trace contamination levels within a 50 nm surface layer. Micro-pit formation also appeared after irradiating cleaved fused silica surfaces at damaging fluences. Linear damage tracks corresponding cleaving tracks were often observed on cleaved surfaces. Soaking cleaved samples in water produced wide laser damage tracks.

  11. Optical and electrical properties of boron doped diamond thin conductive films deposited on fused silica glass substrates

    NASA Astrophysics Data System (ADS)

    Ficek, M.; Sobaszek, M.; Gnyba, M.; Ryl, J.; Gołuński, Ł.; Smietana, M.; Jasiński, J.; Caban, P.; Bogdanowicz, R.

    2016-11-01

    This paper presents boron-doped diamond (BDD) film as a conductive coating for optical and electronic purposes. Seeding and growth processes of thin diamond films on fused silica have been investigated. Growth processes of thin diamond films on fused silica were investigated at various boron doping level and methane admixture. Two step pre-treatment procedure of fused silica substrate was applied to achieve high seeding density. First, the substrates undergo the hydrogen plasma treatment then spin-coating seeding using a dispersion consisting of detonation nanodiamond in dimethyl sulfoxide with polyvinyl alcohol was applied. Such an approach results in seeding density of 2 × 1010 cm-2. The scanning electron microscopy images showed homogenous, continuous and polycrystalline surface morphology with minimal grain size of 200 nm for highly boron doped films. The sp3/sp2 ratio was calculated using Raman spectra deconvolution method. A high refractive index (range of 2.0-2.4 @550 nm) was achieved for BDD films deposited at 500 °C. The values of extinction coefficient were below 0.1 at λ = 550 nm, indicating low absorption of the film. The fabricated BDD thin films displayed resistivity below 48 Ohm cm and transmittance over 60% in the visible wavelength range.

  12. J-Integral Tearing Instability Analysis for 8-Inch Diameter ASTM A106 Steel Pipe.

    DTIC Science & Technology

    1984-05-01

    NUREG 074416. The J/Tmaterial curves for the pipe tests calculated using elastic compliance and DCPD results are shown in Figures 29 and 30...Gudas and J.A. Joyce "Experimental Investigation of Tearing Instability Phenomena for Structural Materials" U.S. Nuclear Regula- tory Commission, NUREG /CR...Tests of Compact and Pipe Specimens Utilizing a Test System Made Compliant by Computer Control", U.S. Nuclear Regulatory Commission Report, NUREG CR

  13. Direct measurement of the nonlinear refractive-index coefficient gamma at 355 nm in fused silica and in BK-10 glass.

    PubMed

    Iii, W T; Smith, W L; Milam, D

    1984-01-01

    We have measured the nonlinear refractive-index coefficient gamma interferometrically at 355 nm in fused silica and in BK-10, a borosilicate crown glass. These measurements are the first reported direct ultraviolet measurements of the nonlinear index of refraction in any transparent glass. Our results are gamma = (2.5 +/- 1.2) x 10(-16) cm(2)/W and gamma = (1.7 +/- 0.8) x 10(-16) cm(2)/W, respectively, for fused silica and BK-10.

  14. High resolution characterization of modifications in fused silica after exposure to low fluence 355 nm laser at different repetition frequencies.

    PubMed

    Li, C H; Ju, X; Jiang, X D; Huang, J; Zhou, X D; Zheng, Z; Wu, W D; Zheng, W G; Li, Z X; Wang, B Y; Yu, X H

    2011-03-28

    We report on the characterization of modifications in fused silica after exposure to low fluence (2 J/cm2) 355 nm laser at repetition frequencies of 1 Hz, 5 Hz and 10 Hz. Synchrotron based XRF spectroscopy is employed to study concentration variation of metal inclusions in the surface layer. Positron annihilation lifetime spectroscopy is used to probe atomic size defects variation in bulk silica. FT-IR is used to characterize changes of bond length and angle of Si-O-Si covalent bond of irradiated silica. Compared to the basic frequency, the big loss of cerium and iron concentration, the size enlargement of vacancy cluster and the decrease of Si-O-Si covalent bond length after 10 Hz laser irradiation are illustrated by our data. These tiny modifications provide important data to investigate laser damage mechanism.

  15. Imaging of single-chromophore molecules in aqueous solution near a fused-silica interface

    NASA Astrophysics Data System (ADS)

    Davis, Lloyd M.; Parker, Wesley C.; Ball, David A.; Williams, John G.; Bashford, Greg R.; Sheaff, Pamela; Eckles, Robert D.; Lamb, Don T.; Middendorf, Lyle R.

    2001-04-01

    Single molecules of unconjugated Bodipy-Texas Red (BTR), BTR-dimer, and BTR conjugated to cysteine, in aqueous solutions are imaged using total-internal-reflection excitation and through-sample collection of fluorescence onto an intensified CCD camera, or a back-illuminated frame transfer CCD. The sample excitation is provided by the beam from a continuous-wave krypton ion laser, or a synchronously-pumped dye laser, operating at 568 nm. In order to essentially freeze molecular motion due to diffusion and thereby enhance image contrast, the laser beam is first passed through a mechanical shutter, which yields a 3-millisecond laser exposure for each camera frame. The laser beam strikes the fused-silica/sample interface at an angle exceeding the critical angle by about 1 degree. The resultant evanescent wave penetrates into the sample a depth of approximately 0.3 microns. Fluorescence from the thin plane of illumination is then imaged onto the camera by a water immersion apochromat (NA 1.2, WD 0.2mm). A Raman notch filter blocks Rayleigh and specular laser scatter and a band-pass-filter blocks most Raman light scatter that originates from the solvent. Single molecules that have diffused into the evanescent zone at the time of laser exposure yield near-diffraction-limited Airy disk images with diameters of ~5 pixels. While most molecules diffuse out of the evanescent zone before the next laser exposure, stationary or slowly moving molecules persisting over several frames, and blinking of such molecules are occasionally observed.

  16. Dental composite resins containing silica-fused ceramic single-crystalline whiskers with various filler levels.

    PubMed

    Xu, H H

    1999-07-01

    Currently available direct-filling composite resins are susceptible to fracture and hence are not recommended for use in large stress-bearing posterior restorations involving cusps. The glass fillers in composites provide only limited reinforcement because of the brittleness and low strength of glass. The aim of the present study was to use ceramic single-crystalline whiskers as fillers to reinforce composites, and to investigate the effect of whisker filler level on composite properties. Silica particles were fused onto the whiskers to facilitate silanization and to roughen the whiskers, thereby improving retention in the matrix. The composite flexural strength, elastic modulus, hardness, and degree of polymerization conversion were measured as a function of whisker filler mass fraction, which ranged from 0% to 70%. Selected composites were polished simulating clinical procedures, and the surface roughness was measured with profilometry. The whisker composite with a filler mass fraction of 55% had a flexural strength (mean +/- SD; n = 6) of 196+/-10 MPa, significantly higher than 83+/-14 MPa of a microfill and 120+/-16 MPa of a hybrid composite control (family confidence coefficient = 0.95; Tukey's multiple comparison). The composite modulus and hardness increased monotonically with filler level. The flexural strength first increased, then plateaued with increasing filler level. The degree of conversion decreased with increasing filler level. The whisker composite had a polished surface roughness similar to that of a conventional hybrid composite (p>0.1; Student's t). To conclude, ceramic whisker reinforcement can significantly improve the mechanical properties of composite resins; the whisker filler level plays a key role in determining composite properties; and the reinforcement mechanisms appear to be crack pinning by whiskers and friction from whisker pullout resisting crack propagation.

  17. Internal electrolyte temperatures for polymer and fused-silica capillaries used in capillary electrophoresis.

    PubMed

    Evenhuis, Christopher J; Guijt, Rosanne M; Macka, Miroslav; Marriott, Philip J; Haddad, Paul R

    2005-11-01

    Polymers are important as materials for manufacturing microfluidic devices for electrodriven separations, in which Joule heating is an unavoidable phenomenon. Heating effects were investigated in polymer capillaries using a CE setup. This study is the first step toward the longer-term objective of the study of heating effects occurring in polymeric microfluidic devices. The thermal conductivity of polymers is much smaller than that of fused silica (FS), resulting in less efficient dissipation of heat in polymeric capillaries. This study used conductance measurements as a temperature probe to determine the mean electrolyte temperatures in CE capillaries of different materials. Values for mean electrolyte temperatures in capillaries made of New Generation FluoroPolymer (NGFP), poly-(methylmethacrylate) (PMMA), and poly(ether ether ketone) (PEEK) capillaries were compared with those obtained for FS capillaries. Extrapolation of plots of conductance versus power per unit length (P/L) to zero power was used to obtain conductance values free of Joule heating effects. The ratio of the measured conductance values at different power levels to the conductance at zero power was used to determine the mean temperature of the electrolyte. For each type of capillary material, it was found that the average increase in the mean temperature of the electrolyte (DeltaT(Mean)) was directly proportional to P/L and inversely proportional to the thermal conductivity (lambda) of the capillary material. At 7.5 W/m, values for DeltaT(Mean) for NGFP, PMMA, and PEEK were determined to be 36.6, 33.8, and 30.7 degrees C, respectively. Under identical conditions, DeltaT(Mean) for FS capillaries was 20.4 degrees C.

  18. Sub-surface mechanical damage distributions during grinding of fused silica

    SciTech Connect

    Suratwala, T I; Wong, L L; Miller, P E; Feit, M D; Menapace, J A; Steele, R A; Davis, P A; Walmer, D

    2005-11-28

    The distribution and characteristics of surface cracking (i.e. sub-surface damage or SSD) formed during standard grinding processes has been investigated on fused silica glass. The SSD distributions of the ground surfaces were determined by: (1) creating a shallow (18-108 {micro}m) wedge/taper on the surface by magneto-rheological finishing; (2) exposing the SSD by HF acid etching; and (3) performing image analysis of the observed cracks from optical micrographs taken along the surface taper. The observed surface cracks are characterized as near-surface lateral and deeper trailing indent type fractures (i.e., chatter marks). The SSD depth distributions are typically described by a single exponential distribution followed by an asymptotic cutoff in depth (c{sub max}). The length of the trailing indent is strongly correlated with a given process. Using established fracture indentation relationships, it is shown that only a small fraction of the abrasive particles are being mechanically loaded and causing fracture, and it is likely the larger particles in the abrasive particle size distribution that bear the higher loads. The SSD depth was observed to increase with load and with a small amount of larger contaminant particles. Using a simple brittle fracture model for grinding, the SSD depth distribution has been related to the SSD length distribution to gain insight into ''effective'' size distribution of particles participating in the fracture. Both the average crack length and the surface roughness were found to scale linearly with the maximum SSD depth (c{sub max}). These relationships can serve as useful rules-of-thumb for nondestructively estimating SSD depth and to identify the process that caused the SSD. In certain applications such as high intensity lasers, SSD on the glass optics can serve as a reservoir for minute amounts of impurities that absorb the high intensity laser light and lead to subsequent laser-induced surface damage. Hence a more scientific

  19. On-machine precision preparation and dressing of ball-headed diamond wheel for the grinding of fused silica

    NASA Astrophysics Data System (ADS)

    Chen, Mingjun; Li, Ziang; Yu, Bo; Peng, Hui; Fang, Zhen

    2013-09-01

    In the grinding of high quality fused silica parts with complex surface or structure using ball-headed metal bonded diamond wheel with small diameter, the existing dressing methods are not suitable to dress the ball-headed diamond wheel precisely due to that they are either on-line in process dressing which may causes collision problem or without consideration for the effects of the tool setting error and electrode wear. An on-machine precision preparation and dressing method is proposed for ball-headed diamond wheel based on electrical discharge machining. By using this method the cylindrical diamond wheel with small diameter is manufactured to hemispherical-headed form. The obtained ball-headed diamond wheel is dressed after several grinding passes to recover geometrical accuracy and sharpness which is lost due to the wheel wear. A tool setting method based on high precision optical system is presented to reduce the wheel center setting error and dimension error. The effect of electrode tool wear is investigated by electrical dressing experiments, and the electrode tool wear compensation model is established based on the experimental results which show that the value of wear ratio coefficient K' tends to be constant with the increasing of the feed length of electrode and the mean value of K' is 0.156. Grinding experiments of fused silica are carried out on a test bench to evaluate the performance of the preparation and dressing method. The experimental results show that the surface roughness of the finished workpiece is 0.03 μm. The effect of the grinding parameter and dressing frequency on the surface roughness is investigated based on the measurement results of the surface roughness. This research provides an on-machine preparation and dressing method for ball-headed metal bonded diamond wheel used in the grinding of fused silica, which provides a solution to the tool setting method and the effect of electrode tool wear.

  20. In-situ monitoring of surface post-processing in large aperture fused silica optics with Optical Coherence Tomography

    SciTech Connect

    Guss, G M; Bass, I l; Hackel, R P; Mailhiot, C; Demos, S G

    2008-02-08

    Optical Coherence Tomography is explored as a method to image laser-damage sites located on the surface of large aperture fused silica optics during post-processing via CO{sub 2} laser ablation. The signal analysis for image acquisition was adapted to meet the sensitivity requirements for this application. A long-working distance geometry was employed to allow imaging through the opposite surface of the 5-cm thick optic. The experimental results demonstrate the potential of OCT for remote monitoring of transparent material processing applications.

  1. Experimental results for nulling the effective thermal expansion coefficient of fused silica fibres under a static stress

    NASA Astrophysics Data System (ADS)

    Bell, Chris J.; Reid, Stuart; Faller, James; Hammond, Giles D.; Hough, Jim; Martin, Iain W.; Rowan, Sheila; Tokmakov, Kirill V.

    2014-03-01

    We have experimentally demonstrated that the effective thermal expansion coefficient of a fused silica fibre can be nulled by placing the fibre under a particular level of stress. Our technique involves heating the fibre and measuring how the fibre length changes with temperature as the stress on the fibre was systematically varied. This nulling of the effective thermal expansion coefficient should allow for the complete elimination of thermoelastic noise and is essential for allowing second generation gravitational wave detectors to reach their target sensitivity. To our knowledge this is the first time that the cancelation of the thermal expansion coefficient with stress has been experimentally observed.

  2. Scanning thermal microscopy and Raman analysis of bulk fused silica exposed to low-energy femtosecond laser pulses.

    PubMed

    Bellouard, Y; Barthel, E; Said, A A; Dugan, M; Bado, P

    2008-11-24

    Low energy femtosecond laser pulses locally increase the refractive index and the hydro-fluoric acid etching rate of fused silica. These phenomena form the basis of a direct-write method to fabricate integrated glass devices that are of particular interest for optofluidics and optomechanical applications. Yet the underlying physical mechanism behind these effects remains elusive, especially the role of the laser polarization. Using Scanning Thermal Microscope and Raman spectrometer we observe in laser affected zones, a localized sharp decrease of the thermal conductivity correlated with an increased presence of low-number SiO(2) cycles. In addition, we find that a high correlation exists between the amount of structural changes and the decrease of thermal conductivity. Furthermore, sub-wavelength periodic patterns are detected for high peak power exposures. Finally, our findings indicate that, to date, the localized densification induced by femtosecond laser pulses remains well below the theoretical value achievable in mechanically densified silica.

  3. Polarization-independent triangular-groove fused-silica gratings with high efficiency at a wavelength of 1550 nm

    NASA Astrophysics Data System (ADS)

    Cao, Hongchao; Zhou, Changhe; Feng, Jijun; Lv, Peng; Ma, Jianyong

    2010-11-01

    We describe polarization-independent triangular-groove fused-silica gratings illuminated by incident lights in the C + L bands as (de)multiplexers for dense wavelength division multiplexing (DWDM) application. The physical mechanisms of the grating can be shown clearly by using the simplified modal method with consideration of the corresponding accumulated average phase difference of two excited propagating grating modes, which illustrates that the grating structure depends mainly on the ratio of the average effective indices difference to the incident wavelength. Exact grating profile is optimized by using the rigorous coupled-wave analysis (RCWA). With the optimized grating parameters, the grating exhibits diffraction efficiencies of greater than 90% under TE- and TM-polarized incident lights for 101 nm spectral bandwidths (1500-1601 nm) and it can reach an efficiency of more than 99% for both polarizations at a wavelength of 1550 nm. Without loss of metal absorption, coating of dielectric film layers, the designed triangular-groove fused-silica grating should be of great interest for DWDM application.

  4. Formation of cylindrical micro-lens array on fused silica glass surface using CO2 laser assisted reshaping technique

    NASA Astrophysics Data System (ADS)

    Choi, Hun-Kook; Ahsan, Md. Shamim; Yoo, Dongyoon; Sohn, Ik-Bu; Noh, Young-Chul; Kim, Jin-Tae; Jung, Deok; Kim, Jin-Hyeok; Kang, Ho-Min

    2015-12-01

    This paper demonstrates the laser assisted formation of plano-convex cylindrical and flat-top curved micro-lens array on fused silica glass surface. Initially, femtosecond laser pulses are irradiated on the sample glass to fabricate periodic linear micro-gratings on the glass surface. Afterwards, we reshape the micro-gratings by several times irradiation of a CO2 laser beam by focusing the laser beam on top of the micro-gratings. As a consequence, plano-convex cylindrical micro-lens array with a period varying from 20 to 40 μm are formed on fused silica glass surface. However, flat-top curved gratings' array is observed on the glass surface for a gratings' period of 50 μm. The fabricated micro-lenses show great consistency in size and shape throughout the sample area. Furthermore, we analyze the formation mechanism of micro-lens array on glass surface using the CO2 laser assisted reshaping technique. The proposed reshaping technique exhibits great potential for forming a large variety of micro-lens arrays on the surface of various transparent materials.

  5. Mitigation of Laser Damage Growth in Fused Silica NIF Optics with a Galvanometer Scanned Carbon Dioxide Laser

    SciTech Connect

    Bass, I L; Draggoo, V; Guss, G M; Hackel, R P; Norton, M A

    2006-04-06

    Economic operation of the National Ignition Facility at the Lawrence Livermore National Laboratory depends on controlling growth of laser damage in the large, high cost optics exposed to UV light at 351 nm. Mitigation of the growth of damage sites on fused silica surfaces greater than several hundred microns in diameter has been previously reported by us using galvanometer scanning of a tightly focused 10.6 {micro}m CO{sub 2} laser spot over an area encompassing the laser damage. Further investigation revealed that fused silica vapor re-deposited on the surface as ''debris'' led to laser damage at unexpectedly low fluences when exposed to multiple laser shots at 351 nm. Additionally, laser power and spatial mode fluctuations in the mitigation laser led to poor repeatability of the process. We also found that the shape of the mitigation pit could produce downstream intensification that could damage other NIF optics. Modifications were made to both the laser system and the mitigation process in order to address these issues. Debris was completely eliminated by these changes, but repeatability and downstream intensification issues still persist.

  6. Results of applying a non-evaporative mitigation technique to laser-initiated surface damage on fused-silica

    SciTech Connect

    Adams, J J; Bolourchi, M; Bude, J D; Guss, G M; Matthews, M J; Nostrand, M C

    2010-10-26

    We present results from a study to determine an acceptable CO{sub 2} laser-based non-evaporative mitigation protocol for use on surface damage sites in fused-silica optics. A promising protocol is identified and evaluated on a set of surface damage sites created under ICF-type laser conditions. Mitigation protocol acceptability criteria for damage re-initiation and growth, downstream intensification, and residual stress are discussed. In previous work, we found that a power ramp at the end of the protocol effectively minimizes the residual stress (<25 MPa) left in the substrate. However, the biggest difficulty in determining an acceptable protocol was balancing between low re-initiation and problematic downstream intensification. Typical growing surface damage sites mitigated with a candidate CO{sub 2} laser-based mitigation protocol all survived 351 nm, 5 ns damage testing to fluences >12.5 J/cm{sup 2}. The downstream intensification arising from the mitigated sites is evaluated, and all but one of the sites has 100% passing downstream damage expectation values. We demonstrate, for the first time, a successful non-evaporative 10.6 {micro}m CO{sub 2} laser mitigation protocol applicable to fused-silica optics used on fusion-class lasers like the National Ignition Facility (NIF).

  7. Second harmonic generation via femtosecond laser fabrication of poled, quasi-phase-matched waveguides in fused silica.

    PubMed

    Ng, Jason C; Herman, Peter R; Qian, Li

    2017-01-15

    Second harmonic generation (SHG) is demonstrated in femtosecond laser written waveguides in fused silica through a combination of thermal poling and laser-based quasi-phase-matching (QPM) techniques. Quasi-phase-matching was controlled by the periodic erasure of induced nonlinearity through femtosecond laser erasure. A maximum SHG conversion efficiency of 6.6±0.5×10-5%/W is reported for the fundamental wavelength of 1552.8 nm with a phase-matching bandwidth of 4.4 nm for a 10.0 mm long waveguide. For a shorter sample, an effective second-order nonlinearity of χ(2)=0.012±0.001  pm/V was measured. Chirped QPM structures for wider SHG bandwidths also were demonstrated. Such periodically poled waveguides are promising for introducing nonlinear optical components within the 3D passive optical circuits that can be flexibly formed in fused silica by femtosecond laser writing.

  8. Combined Advanced Finishing and UV-Laser Conditioning for Producing UV-Damage-Resistant Fused Silica Optics

    SciTech Connect

    Menapace, J A; Penetrante, B; Golini, D; Slomba, A; Miller, P E; Parham, T; Nichols, M; Peterson, J

    2001-11-01

    Laser induced damage initiation on fused silica optics can limit the lifetime of the components when used in high power UV laser environments. Foe example in inertial confinement fusion research applications, the optics can be exposed to temporal laser pulses of about 3-nsec with average fluences of 8 J/cm{sup 2} and peak fluences between 12 and 15 J/cm{sup 2}. During the past year, we have focused on optimizing the damage performance at a wavelength of 355-nm (3{omega}), 3-nsec pulse length, for optics in this category by examining a variety of finishing technologies with a challenge to improve the laser damage initiation density by at least two orders of magnitude. In this paper, we describe recent advances in improving the 3{omega} damage initiation performance of laboratory-scale zirconium oxide and cerium oxide conventionally finished fused silica optics via application of processes incorporating magnetorheological finishing (MRF), wet chemical etching, and UV laser conditioning. Details of the advanced finishing procedures are described and comparisons are made between the procedures based upon large area 3{omega} damage performance, polishing layer contamination, and optical subsurface damage.

  9. Effect of annealing on the laser induced damage of polished and CO2 laser-processed fused silica surfaces

    NASA Astrophysics Data System (ADS)

    Doualle, T.; Gallais, L.; Cormont, P.; Donval, T.; Lamaignère, L.; Rullier, J. L.

    2016-06-01

    We investigate the effect of different heat treatments on the laser-induced damage probabilities of fused silica samples. Isothermal annealing in a furnace is applied, with different temperatures in the range 700-1100 °C and 12 h annealing time, to super-polished fused silica samples. The surface flatness and laser damage probabilities at 3 ns, 351 nm are measured before and after the different annealing procedures. We have found a significant improvement of the initial laser damage probabilities of the silica surface after annealing at 1050 °C for 12 h. A similar study has been conducted on CO2 laser-processed sites on the surface of the samples. Before and after annealing, we have studied the morphology of the sites, the evolution of residual stress, and the laser-induced damage threshold measured at 351 nm, 3 ns. In this case, we observe that the laser damage resistance of the laser created craters can reach the damage level of the bare fused silica surface after the annealing process, with a complete stress relieve. The obtained results are then compared to the case of local annealing process by CO2 laser irradiation during 1 s, and we found similar improvements in both cases. The different results obtained in the study are compared to numerical simulations made with a thermo-mechanical model based on finite-element method that allows the simulation of the isothermal or the local annealing process, the evolution of stress and fictive temperature. The simulation results were found to be very consistent with experimental observations for the stresses evolution after annealing and estimation of the heat affected area during laser-processing based on the density dependence with fictive temperature. Following this work, the temperature for local annealing should reach 1330-1470 °C for an optimized reduction of damage probability and be below the threshold for material removal, whereas furnace annealing should be kept below the annealing point to avoid sample

  10. Infrared, spectral, directional-hemispherical reflectance of fused silica, Teflon polytetrafluoroethylene polymer, chrome oxide ceramic particle surface, Pyromark 2500 paint, Krylon 1602 paint, and Duraflect coating

    NASA Astrophysics Data System (ADS)

    Persky, Merle J.; Szczesniak, Martin

    2008-04-01

    Infrared, spectral, directional-hemispherical reflectivity measurements of polished fused silica, Teflon polytetrafluoroethylene polymer, chrome oxide ceramic particle surface, Pyromark 2500 paint, Krylon 1602 paint, and Duraflect coating are provided. The reflectance was measured with an estimated accuracy of 0.01 to 0.02 units and a precision of 0.005 units. All the surfaces were measured at ambient temperatures. Additionally, the chrome oxide ceramic particle surface was measured at 486 K and the Pyromark 2500 at four temperatures to 877 K. Polarization measurements are also provided for fused silica, Duraflect, chrome oxide ceramic particle surface, and Pyromark 2500 paint. Separate diffuse and specular reflectance components for the Duraflect and chrome oxide ceramic surfaces are included. Fresnel-based predictions for fused silica parallel and perpendicular polarized reflections are compared to measurements. It is notable that the Pyromark 2500 and chrome oxide ceramic particle surfaces exhibit a significant lack of manufacturing repeatability.

  11. High optical transparency and good adhesion of diamond films deposited on fused silica windows with a surface-wave sustained plasma.

    PubMed

    -Airoldi, V T; Borges, C F; Moisan, M; Guay, D

    1997-07-01

    We utilized a microwave plasma reactor based on a surface-wave-sustained discharge for uniform coating of fused silica windows with polycrystalline diamond films. Grain size and average roughness as small as 30 and 2.2 nm, respectively, were obtained, resulting in a uniform loss of transparency of only 10% over the 190-800-nm band for as-deposited 1.5-mum-thick coatings. A pretreatment procedure provides a film coating with a surface resistance to scratching that is approximately a factor of 2 higher than that of bare fused silica.

  12. Effects of chemical etching on the surface quality and the laser induced damage threshold of fused silica optics

    NASA Astrophysics Data System (ADS)

    Pfiffer, Mathilde; Cormont, Philippe; Néauport, Jérôme; Lambert, Sébastien; Fargin, Evelyne; Bousquet, Bruno; Dussauze, Marc

    2016-12-01

    Effects of deep wet etching on the surface quality and the laser induced damage probability have been studied on fused silica samples. Results obtained with a HF/HNO3 solution and a KOH solution were compared on both polished pristine surface and scratched surfaces. The hydrofluoric solution radically deteriorated the surface quality creating a haze on the whole surface and increasing considerably the roughness. For both solutions, neither improvement nor deterioration of the laser damage performances has been observed on the etched surfaces while the laser damage resistance of scratches has been increased to the level of the surface. We conclude that laser damage performances are equivalent with both solutions but an acid etching induces surface degradation that is not experienced with basic etching.

  13. Mechanical quality factor measurements of monolithically suspended fused silica test masses of the GEO 600 gravitational wave detector

    NASA Astrophysics Data System (ADS)

    Smith, J. R.; Cagnoli, G.; Crooks, D. R. M.; Fejer, M. M.; Goßler, S.; Lück, H.; Rowan, S.; Hough, J.; Danzmann, K.

    2004-03-01

    Internal thermal noise is expected to be a limiting noise source in the most sensitive frequency band of the GEO 600 gravitational wave detector. Because thermal noise is directly related to energy dissipation, care has been taken to construct test mass suspensions from low-dissipation materials and to eliminate inter-material rubbing where possible. Recently, the GEO 600 team finished the installation of triple-pendulum suspensions for the optics of the Michelson interferometer. Each of these triple pendulums incorporates a monolithic fused silica pendulum as the lowest stage. We have made internal mode quality factor measurements of three monolithically suspended test masses. Using these measurements we estimate of the level of internal thermal noise in the GEO 600 interferometer.

  14. Optical diagnostics of the laser-induced phase transformations in thin germanium films on silicon, sapphire, and fused silica

    NASA Astrophysics Data System (ADS)

    Novikov, H. A.; Batalov, R. I.; Bayazitov, R. M.; Faizrakhmanov, I. A.; Ivlev, G. D.; Prokop'ev, S. L.

    2015-03-01

    The in-situ procedure is used to study the modification of thin (200-600 nm) germanium films induced by nanosecond pulses of a ruby laser. The films are produced using the ion-beam or magnetron sputtering on single-crystalline silicon (Si), sapphire (Al2O3), and fused silica (α-SiO2) substrates. The results on the dynamics of the laser-induced processes are obtained using the optical probing of the irradiated region at wavelengths of λ = 0.53 and 1.06 μm. The results of probing make it possible to determine the threshold laser energy densities that correspond to the Ge and Si melting and the generation of the Ge ablation plasma versus the amount of deposited Ge and thermophysical parameters of the substrate. The reflection oscillograms are used to obtain the dependences of the melt lifetime on the laser-pulse energy density.

  15. Transmittance and reflectance of crystalline quartz and highand low-water content fused silica from 2 microns to 1 mm

    NASA Technical Reports Server (NTRS)

    Heaney, J. B.; Stewart, K. P.; Hass, G.

    1983-01-01

    The transmittances and reflectances of cultured crystalline quartz, Suprasil, Suprasil W, and Infrasil were compared over the wavelength region from 2 to 1000 microns. The high-water content of Suprasil and the low-water content of cultured crystalline quartz, Suprasil W, and Infrasil were determined by their transmittances measured at 2.73 microns where water content causes high absorption in optical materials. The fact that the fused silicas, both with high- and low-water content, had identical far-IR transmittances and that their transmittances were greatly inferior to that of crystalline quartz led to the conclusion that their inferior transmittance is due to their amorphous structure and not to their water content.

  16. Observation of nonlinear optical phenomena in fused silica and air using a 100 GW, 1.54 um source.

    SciTech Connect

    Rudd, James Van; Law, R. J.; Luk, Ting Shan; Naudeau, Madeline L.; Nelson, Thomas Robert; Cameron, Stewart M.

    2006-02-01

    A 100-GW optical parametric chirped-pulse amplifier system is used to study nonlinear effects in the 1.54 {micro}m regime. When focusing this beam in air, strong third-harmonic generation (THG) is observed, and both the spectra and efficiency are measured. Broadening is observed on only the blue side of the third-harmonic signal and an energy conversion efficiency of 0.2% is achieved. When propagated through a 10-cm block of fused silica, a collimated beam is seen to collapse and form multiple filaments. The measured spectral features span 400-2100 nm. The spectrum is dominated by previously unobserved Stokes emissions and broad emissions in the visible.

  17. Observation of nonlinear optical phenomena in air and fused silica using a 100 GW, 1.54 mum source.

    PubMed

    Naudeau, M L; Law, R J; Luk, T S; Nelson, T R; Cameron, S M; Rudd, J V

    2006-06-26

    A 100-GW optical parametric chirped-pulse amplifier system is used to study nonlinear effects in the 1.54 mum regime. When focusing this beam in air, strong third-harmonic generation (THG) is observed, and both the spectra and efficiency are measured. Broadening is observed on only the blue side of the third-harmonic signal and an energy conversion efficiency of 0.2% is achieved. When propagated through a 10-cm block of fused silica, a collimated beam is seen to collapse and form multiple filaments. The measured spectral features span 400-2100 nm. The spectrum is dominated by previously unobserved Stokes emissions and broad emissions in the visible.

  18. Polarization-independent etching of fused silica based on electrons dynamics control by shaped femtosecond pulse trains for microchannel fabrication.

    PubMed

    Yan, X; Jiang, L; Li, X; Zhang, K; Xia, B; Liu, P; Qu, L; Lu, Y

    2014-09-01

    We propose an approach to realize polarization-independent etching of fused silica by using temporally shaped femtosecond pulse trains to control the localized transient electrons dynamics. Instead of nanograting formation using traditional unshaped pulses, for the pulse delay of pulse trains larger than 1 ps, coherent field-vector-related coupling is not possible and field orientation is lost. The exponential growth of the periodic structures is interrupted. In this case, disordered and interconnected nanostructures are formed, which is probably the main reason of etching independence on the laser polarization. As an application example, square-wave-shaped and arc-shaped microchannels are fabricated by using pulse trains to demonstrate the advantage of the proposed method in fabricating high-aspect-ratio and three-dimensional microchannels.

  19. Comparison of laser-based mitigation of fused silica surface damage using mid- versus far-infrared lasers

    SciTech Connect

    Yang, S T; Matthews, M J; Elhadj, S; Cooke, D; Guss, G M; Draggoo, V G; Wegner, P J

    2009-12-16

    Laser induced growth of optical damage can limit component lifetime and therefore operating costs of large-aperture fusion-class laser systems. While far-infrared (IR) lasers have been used previously to treat laser damage on fused silica optics and render it benign, little is known about the effectiveness of less-absorbing mid-IR lasers for this purpose. In this study, they quantitatively compare the effectiveness and efficiency of mid-IR (4.6 {micro}m) versus far-IR (10.6 {micro}m) lasers in mitigating damage growth on fused silica surfaces. The non-linear volumetric heating due to mid-IR laser absorption is analyzed by solving the heat equation numerically, taking into account the temperature-dependent absorption coefficient {alpha}(T) at {lambda} = 4.6 {micro}m, while far-IR laser heating is well-described by a linear analytic approximation to the laser-driven temperature rise. In both cases, the predicted results agree well with surface temperature measurements based on infrared radiometry, as well as sub-surface fictive temperature measurements based on confocal Raman microscopy. Damage mitigation efficiency is assessed using a figure of merit (FOM) relating the crack healing depth to laser power required, under minimally-ablative conditions. Based on their FOM, they show that for cracks up to at least 500 {micro}m in depth, mitigation with a 4.6 {micro}m mid-IR laser is more efficient than mitigation with a 10.6 {micro}m far-IR laser. This conclusion is corroborated by direct application of each laser system to the mitigation of pulsed laser-induced damage possessing fractures up to 225 {micro}m in depth.

  20. Effects of Ti charge state, ion size and beam-induced compaction on the formation of Ag metal nanoparticles in fused silica

    NASA Astrophysics Data System (ADS)

    Magruder, R. H.; Meldrum, A.; Haglund, R. F.

    2015-04-01

    Metal nanoparticles formed by ion implantation in fused silica exhibit linear and nonlinear optical properties that can be altered by co-doping the silica substrate with transition-metal ions. For example, implantation of scandium in fused silica creates a directional optical dichroism due to the different spatial distribution of silver nanoparticles subsequently formed by Ag ion implantation. In this paper, we show that implantation of titanium ions alters the short- and intermediate-range order in the silica and thereby alters the diffusion and nucleation processes that lead to formation of silver nanoparticles. In particular, the dichroic response observed for Ag nanoparticles in Sc-implanted silica is, with one exception, in Ti-implanted silica. Compaction of the silica due to the ion implantation process appears to be similar for both Sc and Ti implantations, based on the observed shift of the 1,124 cm-1 transverse-optical phonon mode in the infrared reflectance spectrum. However, differences in chemical reactivity, bond lengths and electronic structure of Sc and Ti produce changes in electronic structure and strain that are sensitively reflected in the reflectance spectra of the Ag nanoparticles. These differences lead to modifications in the size, shape and spatial distributions of the silver nanoparticles and offer a powerful means of controlling their optical properties.

  1. Identification of the formation phases of filamentary damage induced by nanosecond laser pulses in bulk fused silica

    SciTech Connect

    Shen, Chao; Xu, Zhongjie; Chambonneau, Maxime E-mail: jiangtian198611@163.com; Cheng, Xiang'ai; Jiang, Tian E-mail: jiangtian198611@163.com

    2015-09-14

    Employing a pump-probe polarization-based two-frame shadowgraphy setup, the formation of filamentary damage induced in bulk fused silica by a nanosecond pulse at 1064 nm is investigated with a picosecond probe. Three different phases are exhibited in the damage experiments. The first phase is the formation of a micrometric plasma channel along the laser direction during the beginning of the pulse likely caused by multi-photon ionization. This channel exhibits growth during ∼400 ps, and the newly grown plasma is discrete. Then, during the end of the pulse, this channel evolves into a tadpole-like morphology showing an elliptical head upstream the laser flux followed by a thin tail. This observed asymmetry is attributed to shielding effects caused by both the plasma and hot modified silica. Once the damage shows its almost final morphology, a last phase consists in the launch of a pressure wave enlarging it after the laser pulse. The physical mechanisms that might be involved in the formation of plasma channels are discussed. The experimental data are first confronted to the moving breakdown model which overestimates the filamentary damage length. Finally, taking into account the temporal shape of the laser pulses, the coupling between Kerr-induced self-focusing and stimulated Brillouin scattering is discussed to interpret the observations.

  2. Thermo-mechanical simulations of CO2 laser-fused silica interactions

    NASA Astrophysics Data System (ADS)

    Doualle, T.; Gallais, L.; Cormont, P.; Hébert, D.; Combis, P.; Rullier, J.-L.

    2016-03-01

    CO2 laser heating of silica glass is used in many scientific and industrial applications. Particularly, localized CO2 laser heating of silica glass has demonstrated its ability to mitigate surface damage on optics used for high power laser applications. To develop such applications, the control of temperature, heat affected area, and resulting mechanical stresses are critical. Therefore, it is necessary to understand the silica transformation, the material ejection, and the thermo-mechanical stresses induced by the laser heating and subsequent cooling. In this paper, we detail the development of comprehensive thermo-mechanical numerical simulations of these physical processes, based on finite-element method. The approach is developed for 2D or 3D cases to tackle the case of a moving beam at the surface of the sample, and we particularly discuss the choice of the different parameters based on bibliographic inputs. The thermal and mechanical numerical results have been compared to different dedicated experimental studies: infrared thermography measurements at the surface of the irradiated area, optical profilometry measurements of the laser-processed sites, and photo-elastic measurements. Very consistent results are obtained between numerical and experimental results for the description of the temperature gradients, the material ejection, and the residual stresses.

  3. Study of CO2 laser smoothing of surface roughness in fused silica

    SciTech Connect

    Shen, N; Matthews, J; Fair, J E; Britten, J A; Nguyen, H T; Cooke, D; Elhadj, S; Henshaw, D; Guss, G M; Guss, G M; Yang, T

    2009-11-03

    Small micrometer-sized roughness on optical surfaces, caused by laser damage and/or redeposition of laser ablated material, can cause local electric field intensification which may lead to damage initiation both on the optics and/or downstream. We examined the smoothing of etched periodic surface structures on SiO{sub 2} substrate with 10.6 {micro}m CO{sub 2} laser using atomic force microscopy. The characteristic surface tension driven mass flow of the glass under different laser parameters were simulated using computational fluid dynamics and correlated with experimental results. We found that during CO{sub 2} laser polishing the estimate viscosity of the silica glass appears to be higher than typical literature values measured at a temperature similar to the laser heating conditions. This discrepancy can be explained by the observation that at high temperature, a significant portion of the hydroxyl content in the layer of heated silica glass can diffuse out resulting in a much stiffer glass.

  4. Defects Induced in Fused Silica by High Power UV Laser Pulses at 355 nm

    SciTech Connect

    Stevens-Kalceff, M A; Stesmans, A; Wong, J

    2001-03-23

    Point defects induced in high quality optical-grade based silica by high power (>30 J/cm{sup 2}) 355 nm laser pulses have been investigated to elucidate the nature of laser damage in transparent optics designed for use at the National Ignition Facility (NIF). Six defects have been identified: the NBOHC (non-bridging oxygen hole center), a STE (self-trapped exciton), an ODC (oxygen-deficient center), interstitial oxygen, the E'{sub {gamma}}, and E'{sub 74}. The former four defects were identified and spatially resolved in the damage craters using cathodoluminescence (CL) microanalysis (spectroscopy and microscopy). The latter two defects were identified using ESR spectroscopy at cryogenic temperatures. These defects are unlikely to be a prime factor in damage growth by subsequent laser pulses. Their concentration is too low to effect a high enough temperature rise by a volume absorption mechanism.

  5. Comparing the use of 4.6 um lasers versus 10.6 um lasers for mitigating damage site growth on fused silica surfaces

    SciTech Connect

    Yang, S T; Matthews, M J; Elhadj, S; Cooke, D; Guss, G M; Draggoo, V G; Wegner, P J

    2010-10-21

    The advantage of using mid-infrared (IR) 4.6 {micro}m lasers, versus far-infrared 10.6 {micro}m lasers, for mitigating damage growth on fused silica is investigated. In contrast to fused silica's high absorption at 10.6 {micro}m, silica absorption at 4.6 {micro}m is two orders of magnitude less. The much reduced absorption at 4.6 {micro}m enables deep heat penetration into fused silica when it is heated using the mid-IR laser, which in turn leads to more effective mitigation of damage sites with deep cracks. The advantage of using mid-IR versus far-IR laser for damage growth mitigation under non-evaporative condition is quantified by defining a figure of merit (FOM) that relates the crack healing depth to laser power required. Based on our FOM, we show that for damage cracks up to at least 500 {micro}m in depth, mitigation using a 4.6 {micro}m mid-IR laser is more efficient than mitigation using a 10.6 {micro}m far-IR laser.

  6. Effect of rogue particles on the sub-surface damage of fused silica during grinding/polishing

    SciTech Connect

    Suratwala, T I; Steele, R; Feit, M D; Wong, L; Miller, P E; Menapace, J A; Davis, P J

    2007-05-02

    The distribution and characteristics of surface cracks (i.e., sub-surface damage or scratching) on fused silica formed during grinding/polishing resulting from the addition of rogue particles in the base slurry has been investigated. Fused silica samples (10 cm diameter x 1 cm thick) were: (1) ground by loose abrasive grinding (alumina particles 9-30 {micro}m) on a glass lap with the addition of larger alumina particles at various concentrations with mean sizes ranging from 15-30 {micro}m, or (2) polished (using 0.5 {micro}m cerium oxide slurry) on various laps (polyurethanes pads or pitch) with the addition of larger rogue particles (diamond (4-45 {micro}m), pitch, dust, or dried Ceria slurry agglomerates) at various concentrations. For the resulting ground samples, the crack distributions of the as-prepared surfaces were determined using a polished taper technique. The crack depth was observed to: (1) increase at small concentrations (>10{sup -4} fraction) of rogue particles; and (2) increase with rogue particle concentration to crack depths consistent with that observed when grinding with particles the size of the rogue particles alone. For the polished samples, which were subsequently etched in HF:NH{sub 4}F to expose the surface damage, the resulting scratch properties (type, number density, width, and length) were characterized. The number density of scratches increased exponentially with the size of the rogue diamond at a fixed rogue diamond concentration suggesting that larger particles are more likely to lead to scratching. The length of the scratch was found to increase with rogue particle size, increase with lap viscosity, and decrease with applied load. At high diamond concentrations, the type of scratch transitioned from brittle to ductile and the length of the scratches dramatically increased and extended to the edge of the optic. The observed trends can explained semi-quantitatively in terms of the time needed for a rogue particle to penetrate into a

  7. Synthesis and characterization of size-controlled vanadium dioxide nanocrystals in a fused silica matrix

    NASA Astrophysics Data System (ADS)

    Lopez, R.; Boatner, L. A.; Haynes, T. E.; Feldman, L. C.; Haglund, R. F.

    2002-10-01

    Vanadium dioxide single-crystal precipitates with controlled particle sizes were produced in an amorphous, fused SiO2 host by the stoichiometric coimplantation of vanadium and oxygen ions and subsequent thermal processing. The effects of the vanadium dioxide nanocrystal size, nanocrystal morphology, and particle/host interactions on the VO2 semiconductor-to-metal phase transition were characterized. VO2 nanoparticles embedded in amorphous SiO2 exhibit a sharp phase transition with a hysteresis that is up to 50 °C in width—one of the largest values ever reported for this transition. The relative decrease in the optical transmission in the near-infrared region in going from the semiconducting to the metallic phase of VO2 ranges from 20% to 35%. Both the hysteresis width and the transition temperature are correlated with the size of the precipitates. Doping the embedded VO2 particles with ions such as titanium alters the characteristics of the phase transition, pointing the way to control the hysteresis behavior over a wide range of values and providing insight into the operative physical mechanisms.

  8. Microstructure variation in fused silica irradiated by different fluence of UV laser pulses with positron annihilation lifetime and Raman scattering spectroscopy

    NASA Astrophysics Data System (ADS)

    Li, Chunhong; Zheng, Wanguo; Zhu, Qihua; Chen, Jun; Wang, B. Y.; Ju, Xin

    2016-10-01

    We present an original study on the non-destructive evaluation of the microstructure evolution of fused silica induced by pulsed UV laser irradiation at low fluence (less than 50% Fth). Positron annihilation spectroscopy discloses that the spatial size of the vacancy cluster is increased exponentially with the linearly elevated laser fluence. Particularly, the vacancy cluster size in bulk silica is significantly increased by 14.5% after irradiated by pulsed 355 nm laser at F = 14 J/cm2 (50% Fth), while the void size varies only ∼2%. UV laser-excited Raman results suggest that the bond length and average bond angle of Sisbnd Osbnd Si bridging bond are both slightly reduced. Results reveals that the rearrangement process of (Sisbnd O)n fold rings and breakage of the Sisbnd O bridging bond in bulk silica occurred during pulsed UV laser irradiation. The micro-structural changes were taken together to clarify the effect of sub-threshold laser fluence on material stability of silica glass. The obtained data provide important information for studying material stability and controlling the lifetime of fused silica optics for high power laser system.

  9. Rapid micromachining of high aspect ratio holes in fused silica glass by high repetition rate picosecond laser

    NASA Astrophysics Data System (ADS)

    Karimelahi, Samira; Abolghasemi, Ladan; Herman, Peter R.

    2014-01-01

    We present multiple methods of high aspect ratio hole drilling in fused silica glass, taking advantage of high power and high repetition rate picosecond lasers and flexible beam delivery methods to excise deep holes with minimal collateral damage. Combinations of static and synchronous scanning of laser focus were explored over a range of laser repetition rates and burst-train profiles that dramatically vary laser plume interaction dynamics, heat-affected zone, and heat accumulation physics. Chemically assisted etching of picosecond laser modification tracks are also presented as an extension from femtosecond laser writing of volume nanograting to form high aspect ratio (77) channels. Processing windows are identified for the various beam delivery methods that optimize the laser exposure over energy, wavelength, and repetition rate to reduce microcracking and deleterious heating effects. The results show the benefits of femtosecond laser interactions in glass extend into the picosecond domain, where the attributes of higher power further yield wide processing windows and significantly faster fabrication speed. High aspect ratio holes of 400 μm depth were formed over widely varying rates of 333 holes per second for mildly cracked holes in static-focal positioning through to one hole per second for low-damage and taper free holes in synchronous scanning.

  10. Flexible and efficient eletrokinetic stacking of DNA and proteins at an HF etched porous junction on a fused silica capillary.

    PubMed

    Wu, Zhi-Yong; Fang, Fang; He, Yan-Qin; Li, Ting-Ting; Li, Jing-Jing; Tian, Li

    2012-08-21

    Better understanding of the mechanism is important for exploring the potentials of a preconcentration method. In this work, we show for the first time that the HF etched porous junction on a fused silica capillary behaves not only as a filter but also as an integrated nanofluidic interface. This junction exhibits an obvious ion concentration polarization (CP) effect, with which highly efficient electrokinetic stacking (ES) inside the capillary can be achieved without molecular size or charge type limitation. Two major types of CP based ES were proposed, and an autostop etching principle was presented for avoiding overetching. The ES can be performed in a broad range of pH and buffer concentration. Over a billion times of concentration was demonstrated by a fluorescein probe with laser induced fluorescent (LIF) detection. ES of fluorescently labeled and native DNA and protein were characterized by charge-coupled device (CCD) imaging and online capillary gel electrophoresis (CGE) with ultraviolet (UV) absorption detections, respectively. With this junction, highly efficient ES can be performed easily by voltage manipulation without any mechanical operation. We may foresee that the performance of capillary-based conventional and chip electrophoresis could be greatly enhanced with this junction in the analysis of low abundance biomolecules.

  11. Imaging System to Measure Kinetics of Material Cluster Ejection During Exit-Surface Damage Initiation and Growth in Fused Silica

    SciTech Connect

    Raman, R N; Negres, R A; Demos, S G

    2009-10-29

    Laser-induced damage on the surface of optical components typically is manifested by the formation of microscopic craters that can ultimately degrade the optics performance characteristics. It is believed that the damage process is the result of the material exposure to high temperatures and pressures within a volume on the order of several cubic microns located just below the surface. The response of the material following initial localized energy deposition by the laser pulse, including the timeline of events and the individual processes involved during this timeline, is still largely unknown. In this work we introduce a time-resolved microscope system designed to enable a detailed investigation of the sequence of dynamic events involved during surface damage. To best capture individual aspects of the damage timeline, this system is employed in multiple imaging configurations (such as multi-view image acquisition at a single time point and multi-image acquisition at different time points of the same event) and offers sensitivity to phenomena at very early delay times. The capabilities of this system are demonstrated with preliminary results from the study of exit-surface damage in fused silica. The time-resolved images provide information on the material response immediately following laser energy deposition, the processes later involved during crater formation or growth, the material ejecta kinetics, and overall material motion and transformation. Such results offer insight into the mechanisms governing damage initiation and growth in the optical components of ICF class laser systems.

  12. An Improved Method of Mitigating Laser Induced Surface Damage Growth in Fused Silica Using a Rastered, Pulsed CO2 Laser

    SciTech Connect

    Bass, I L; Guss, G M; Nostrand, M J; Wegner, P L

    2010-10-21

    A new method of mitigating (arresting) the growth of large (>200 m diameter and depth) laser induced surface damage on fused silica has been developed that successfully addresses several issues encountered with our previously-reported large site mitigation technique. As in the previous work, a tightly-focused 10.6 {micro}m CO{sub 2} laser spot is scanned over the damage site by galvanometer steering mirrors. In contrast to the previous work, the laser is pulsed instead of CW, with the pulse length and repetition frequency chosen to allow substantial cooling between pulses. This cooling has the important effect of reducing the heat-affected zone capable of supporting thermo-capillary flow from scale lengths on the order of the overall scan pattern to scale lengths on the order of the focused laser spot, thus preventing the formation of a raised rim around the final mitigation site and its consequent down-stream intensification. Other advantages of the new method include lower residual stresses, and improved damage threshold associated with reduced amounts of redeposited material. The raster patterns can be designed to produce specific shapes of the mitigation pit including cones and pyramids. Details of the new technique and its comparison with the previous technique will be presented.

  13. High-resolution 3-D imaging of surface damage sites in fused silica with Optical Coherence Tomography

    SciTech Connect

    Guss, G; Bass, I; Hackel, R; Mailhiot, C; Demos, S G

    2007-10-30

    In this work, we present the first successful demonstration of a non-contact technique to precisely measure the 3D spatial characteristics of laser induced surface damage sites in fused silica for large aperture laser systems by employing Optical Coherence Tomography (OCT). What makes OCT particularly interesting in the characterization of optical materials for large aperture laser systems is that its axial resolution can be maintained with working distances greater than 5 cm, whether viewing through air or through the bulk of thick optics. Specifically, when mitigating surface damage sites against further growth by CO{sub 2} laser evaporation of the damage, it is important to know the depth of subsurface cracks below the damage site. These cracks are typically obscured by the damage rubble when imaged from above the surface. The results to date clearly demonstrate that OCT is a unique and valuable tool for characterizing damage sites before and after the mitigation process. We also demonstrated its utility as an in-situ diagnostic to guide and optimize our process when mitigating surface damage sites on large, high-value optics.

  14. Parametric study of the damage ring pattern in fused silica induced by multiple longitudinal modes laser pulses

    SciTech Connect

    Chambonneau, M. Grua, P.; Rullier, J.-L.; Lamaignère, L.; Natoli, J.-Y.

    2015-03-14

    With the use of multiple longitudinal modes nanosecond laser pulses at 1064 nm, laser damage sites at the exit surface of fused silica clearly and systematically exhibit ring patterns. It has been shown in our previous works that the apparent chronology of rings was closely related to the temporal shape of the laser pulses. This particular correspondence had suggested an explanation of the ring morphology formation based on the displacement of an ionization front in the surrounding air. To provide a former basis for this hypothesis and deeper understanding of ring pattern formation, additional experiments have been performed. First, the impact of fluence has been investigated, revealing that a wide variety of damage sites are produced within a very narrow fluence range; this fact involves the chronology of appearance of a surface plasma during the laser pulse. The sizes of the damage sites are proportional to the fluence of their expansion occurring between the beginning of the plasma and the end of the laser pulse. Second, specific experiments have been carried out at different angles of incidence, resulting in egg-shaped patterns rather than circular ones. This behavior can be explained by our previous hypothesis of creation of a plasma in air, its expansion being tightly conditioned by the illumination angle. This series of experiments, in which the angle of incidence is varied up to 80°, permits us to link quantitatively the working hypothesis of ionization front propagation with theoretical hydrodynamics modeling.

  15. Parametric study of the damage ring pattern in fused silica induced by multiple longitudinal modes laser pulses

    NASA Astrophysics Data System (ADS)

    Chambonneau, M.; Grua, P.; Rullier, J.-L.; Natoli, J.-Y.; Lamaignère, L.

    2015-03-01

    With the use of multiple longitudinal modes nanosecond laser pulses at 1064 nm, laser damage sites at the exit surface of fused silica clearly and systematically exhibit ring patterns. It has been shown in our previous works that the apparent chronology of rings was closely related to the temporal shape of the laser pulses. This particular correspondence had suggested an explanation of the ring morphology formation based on the displacement of an ionization front in the surrounding air. To provide a former basis for this hypothesis and deeper understanding of ring pattern formation, additional experiments have been performed. First, the impact of fluence has been investigated, revealing that a wide variety of damage sites are produced within a very narrow fluence range; this fact involves the chronology of appearance of a surface plasma during the laser pulse. The sizes of the damage sites are proportional to the fluence of their expansion occurring between the beginning of the plasma and the end of the laser pulse. Second, specific experiments have been carried out at different angles of incidence, resulting in egg-shaped patterns rather than circular ones. This behavior can be explained by our previous hypothesis of creation of a plasma in air, its expansion being tightly conditioned by the illumination angle. This series of experiments, in which the angle of incidence is varied up to 80°, permits us to link quantitatively the working hypothesis of ionization front propagation with theoretical hydrodynamics modeling.

  16. Correlating optical damage threshold with intrinsic defect populations in fused silica as a function of heat treatment temperature

    SciTech Connect

    Shen, N.; Matthews, M. J.; Elhadj, S.; Miller, P. E.; Nelson, A. J.; Hamilton, J.

    2013-04-03

    Here, chemical vapor deposition (CVD) is used for the production of fused silica optics in high-power laser applications. However, relatively little is known about the ultraviolet laser damage threshold of CVD films and how they relate to intrinsic defects produced during deposition. We present here a study relating structural and electronic defects in CVD films to 355 nm pulsed-laser damage threshold as a function of post-deposition annealing temperature (THT). Plasma-enhanced CVD based on SiH4/N2O under oxygen-rich conditions was used to deposit 1.5, 3.1 and 6.4 µm thick films on etched SiO2 substrates. Rapid annealing was performed using a scanned CO2 laser beam up to THT ~ 2100 K. The films were then characterized using x-ray photoemission spectroscopy, Fourier transform infrared spectroscopy (FTIR) and photoluminescence spectroscopy. A gradual transition in the damage threshold of annealed films was observed for THT values up to 1600 K, correlating with a decrease in non-bridging silanol and oxygen deficient centres. An additional sharp transition in damage threshold also occurs at ~1850 K indicating substrate annealing. Based on our results, a mechanism for damage-related defect annealing is proposed, and the potential of using high-THT CVD SiO2 to mitigate optical damage is also discussed.

  17. Verifying an all fused silica miniature optical fiber tip pressure sensor performance with turbine engine field test

    NASA Astrophysics Data System (ADS)

    Wang, Xingwei; Xu, Juncheng; Zhu, Yizheng; Yu, Bing; Han, Ming; Wang, Zhuang; Cooper, Kristie L.; Pickrell, Gary R.; Wang, Anbo; Ringshia, Aditya; Ng, Wing

    2005-11-01

    Pressure sensors are the key elements for industrial monitoring and control systems to lower equipment maintenance cost, improve fuel economy, reduce atmospheric pollution, and provide a safer workplace. However, the testing environment is usually harsh. For example, inside the turbine engine, temperatures might exceed 600°C and pressures might exceed 100psi (690kPa), where most current available sensors cannot survive. Moreover, due to the restricted space for installation, miniature size of the sensor is highly desirable. To meet these requirements, a novel type of all fused silica optic fiber tip pressure sensor with a 125μm diameter was developed. It is a diaphragm based pressure sensor in which a Fabry-Perot interferometer is constructed by the end face of an optical fiber and the surface of a diaphragm connected by a short piece of hollow fiber. The FP cavity length and the interference pattern will change according to ambient pressure variation. Its main improvement with respect to previously developed optical sensors, such as those utilizing techniques of wet etching, anodic bonding and sol-gel bonding, is the fact that no chemical method is needed during the cavity fabrication. Its dynamic pressure performance was verified in a turbine engine field test, demonstrating not only that it can safely and reliably function near the fan of a turbine engine for more than two hours, but also that its performance is consistent with that of a commercial Kulite sensor.

  18. Laser-based dynamic evaporation and surface shaping of fused silica with assist gases: a path to rimless laser machining

    NASA Astrophysics Data System (ADS)

    Elhadj, S.; Matthews, M. J.; Guss, G. M.; Bass, I. L.

    2013-12-01

    Evaporation and ablation are fundamental processes which drive laser-material processing performance. In applications where surface shape is important, control of the temperature field and the resulting spatially varying material response must be considered. For that purpose, assist gases are useful in, first, lowering treatment temperatures and, second, in changing interfacial and bulk chemistry to limit capillary-driven flow. Additionally, laser-matter coupling is influenced by pulse length as it determines the heat affected zone. Using infrared imaging of CO2 laser-heated fused silica and surface profile measurements, we derive temperature and time dependent pitting rates along with shapes for a range of gases that include hydrogen, nitrogen, air, and helium. In the range of 1,500-4,500 K, evaporation, flow, and densification are shown to contribute to the pit shape. Analysis reveals a strong and complex dependence of rim formation on heating time and gas chemistry, mostly by lowering treatment temperature. Under dynamic heating, chemicapillarity appears to help in lowering rim height, in spite of the reactants mass transport limitations. Results on this gas-assisted approach suggest the possibility for sub-nanometer "rimless" laser-based machining.

  19. High-temperature measurement with Brillouin optical time domain analysis of an annealed fused-silica single-mode fiber.

    PubMed

    Bao, Yi; Chen, Genda

    2016-07-15

    The effect of annealing is experimentally studied for a fused silica, fully distributed fiber optic sensor based on the pulse pre-pump Brillouin optical time domain analysis (PPP-BOTDA). Within a heating rate of 4.3°C/min and 30.6°C/min, and a sustained peak temperature for 120 and 240 min, annealing extended the sensor's upper operation temperature from 800°C to 1000°C and reduced the sensor's measurement variability over a temperature range of 22°C to 1000°C with a maximum Brillouin frequency variation of 1%. The annealed sensor had a linearly decreasing Brillouin frequency sensitivity from 1.349×10-3  GHz/°C at 22°C to 0.419×10-3  GHz/°C at 1000°C. The time required to achieve a stable annealing effect decayed exponentially with annealing temperature.

  20. Time-Resolved Imaging of Material Response Following Laser-Induced Breakdown in the Bulk and Surface of Fused Silica

    SciTech Connect

    Raman, R N; Negres, R A; DeMange, P; Demos, S G

    2010-02-04

    Optical components within high energy laser systems are susceptible to laser-induced material modification when the breakdown threshold is exceeded or damage is initiated by pre-existing impurities or defects. These modifications are the result of exposure to extreme conditions involving the generation of high temperatures and pressures and occur on a volumetric scale of the order of a few cubic microns. The response of the material following localized energy deposition, including the timeline of events and the individual processes involved during this timeline, is still largely unknown. In this work, we investigate the events taking place during the entire timeline in both bulk and surface damage in fused silica using a set of time-resolved microscopy systems. These microscope systems offer up to 1 micron spatial resolution when imaging static or dynamic effects, allowing for imaging of the entire process with adequate temporal and spatial resolution. These systems incorporate various pump-probe geometries designed to optimize the sensitivity for detecting individual aspects of the process such as the propagation of shock waves, near-surface material motion, the speed of ejecta, and material transformations. The experimental results indicate that the material response can be separated into distinct phases, some terminating within a few tens of nanoseconds but some extending up to about 100 microseconds. Overall the results demonstrate that the final characteristics of the modified region depend on the material response to the energy deposition and not on the laser parameters.

  1. Residual stress and damage-induced critical fracture on CO2 laser treated fused silica

    SciTech Connect

    Matthews, M; Stolken, J; Vignes, R; Norton, M

    2009-11-02

    Localized damage repair and polishing of silica-based optics using mid- and far-IR CO{sub 2} lasers has been shown to be an effective method for increasing optical damage threshold in the UV. However, it is known that CO{sub 2} laser heating of silicate surfaces can lead to a level of residual stress capable of causing critical fracture either during or after laser treatment. Sufficient control of the surface temperature as a function of time and position is therefore required to limit this residual stress to an acceptable level to avoid critical fracture. In this work they present the results of 351 nm, 3 ns Gaussian damage growth experiments within regions of varying residual stress caused by prior CO{sub 2} laser exposures. Thermally stressed regions were non-destructively characterized using polarimetry and confocal Raman microscopy to measure the stress induced birefringence and fictive temperature respectively. For 1 {approx} 40s square pulse CO{sub 2} laser exposures created over 0.5-1.25 kW/cm{sup 2} with a 1-3 mm 1/e{sup 2} diameter beam (T{sub max} {approx} 1500-3000 K), the critical damage site size leading to fracture increases weakly with peak temperature, but shows a stronger dependence on cooling rate, as predicted by finite element hydrodynamics simulations. Confocal micro-Raman was used to probe structural changes to the glass over different thermal histories and indicated a maximum fictive temperature of 1900K for T{sub max} {ge} 2000 K. The effect of cooling rate on fictive temperature caused by CO{sub 2} laser heating are consistent with finite element calculations based on a Tool-Narayanaswamy relaxation model.

  2. Nanosecond laser-induced back side wet etching of fused silica with a copper-based absorber liquid

    NASA Astrophysics Data System (ADS)

    Lorenz, Pierre; Zehnder, Sarah; Ehrhardt, Martin; Frost, Frank; Zimmer, Klaus; Schwaller, Patrick

    2014-03-01

    Cost-efficient machining of dielectric surfaces with high-precision and low-roughness for industrial applications is still challenging if using laser-patterning processes. Laser induced back side wet etching (LIBWE) using UV laser pulses with liquid heavy metals or aromatic hydrocarbons as absorber allows the fabrication of well-defined, nm precise, free-form surfaces with low surface roughness, e.g., needed for optical applications. The copper-sulphatebased absorber CuSO4/K-Na-Tartrate/NaOH/formaldehyde in water is used for laser-induced deposition of copper. If this absorber can also be used as precursor for laser-induced ablation, promising industrial applications combining surface structuring and deposition within the same setup could be possible. The etching results applying a KrF excimer (248 nm, 25 ns) and a Nd:YAG (1064 nm, 20 ns) laser are compared. The topography of the etched surfaces were analyzed by scanning electron microscopy (SEM), white light interferometry (WLI) as well as laser scanning microscopy (LSM). The chemical composition of the irradiated surface was studied by energy-dispersive X-ray spectroscopy (EDX) and Fourier transform infrared spectroscopy (FT-IR). For the discussion of the etching mechanism the laser-induced heating was simulated with finite element method (FEM). The results indicate that the UV and IR radiation allows micro structuring of fused silica with the copper-based absorber where the etching process can be explained by the laser-induced formation of a copper-based absorber layer.

  3. Development of a laser damage growth mitigation process, based on CO2 laser micro processing, for the Laser MegaJoule fused silica optics

    NASA Astrophysics Data System (ADS)

    Doualle, Thomas; Gallais, Laurent; Monneret, Serge; Bouillet, Stephane; Bourgeade, Antoine; Ameil, Christel; Lamaignère, Laurent; Cormont, Philippe

    2016-12-01

    In the context of high power laser systems, the laser damage resistance of fused silica surfaces at 351 nm in the nanosecond regime is a major concern. Under successive nanosecond laser irradiations, an initiated damage can grow which can make the component unsuitable. The localized CO2 laser processing has demonstrated its ability to mitigate (stopping) laser damage growth. In order to mitigate large damage sites (millimetric), a method based on fast microablation of silica has been proposed by Bass et al. [Bass et al., Proc. SPIE 7842, 784220 (2010)]. This is accomplished by scanning of the CO2 laser spot with a fast galvanometer beam scanner to form a crater with a typical conical shape. The objective of the present work is to develop a similar fast micro-ablation process for application to the Laser MegaJoule optical components. We present in this paper the developed experimental system and process. We describe also the characterization tools used in this study for shape measurements which are critical for the application. Experimental and numerical studies of the downstream intensifications, resulting of cone formation on the fused silica surface, are presented. The experimental results are compared to numerical simulations for different crater shape in order to find optimal process conditions to minimize the intensifications in the LMJ configuration. We show the laser damage test experimental conditions and procedures to evaluate the laser damage resistance of the mitigated sites and discuss the efficiency of the process for our application.

  4. Determination of Hydrogen Diffusion Coefficients in Fused Silica From 23 to 250°C Using Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

    Shang, L.; Chou, I.; Lu, W.; Burruss, R. C.

    2008-12-01

    The oxygen buffer technique is routinely used in experimental studies of redox sensitive geochemical reactions at elevated pressures (P) and temperatures (T). However, this technique is limited to T above about 400°C due to the low permeability of sample containers (Pt or Ag-Pd alloys) to hydrogen at lower T. Preliminary results of Chou et al. (Geochim. Cosmochim. Acta, 2008, doi:10.1016/j.gca.2008.07.030) indicate that the use of fused silica capillary (FSC) container may extend this technique to lower T. In this study, hydrogen diffusion coefficients (D) in FSC were determined from 23 to 250°C by measuring the loss of hydrogen from the FSC containers (0.3 mm OD, 0.1 mm ID, and ~10 mm long) with Raman spectroscopy using CO2 as an internal standard. First, CO2 was loaded cryogenically in a FSC capsule (Chou et al., ibid.). The capsule was then inserted in a protective ceramic tube, sealed in a gold capsule containing Fe powder and water, and heated at 300°C under 100 MPa of Ar external P in a cold-seal pressure vessel for several days allowing H2 to diffuse into the capsule. After quench, the Raman spectra were collected and the initial relative concentration of hydrogen in the silica capsule was derived from the peak height ratios between H2 (near 587 cm-1) and CO2 (near 1387 cm- 1). The sample capsule was then heated at a fixed T at one atmosphere to let H2 diffuse out of the capsule, and the changes of hydrogen concentration were monitored by Raman spectroscopy after quench. This process was repeated with different heating durations at 23 (room T), 50, 102, 157, 200, and 250°C. The values of D (in cm2s-1) in FSC were obtained by fitting the observed changes of hydrogen concentration to an equation based on Fick's second law. Our results can be represented by: Ln D (±0.14) = (-39810/RT) - 9.5491 (r2 = 0.9985) where R is the gas constant, and T in Kelvin. The slope corresponds to an activation energy of 39.81 kJ/mol. Our D values are about a half order of

  5. Silica sulfuric acid: a reusable solid catalyst for one pot synthesis of densely substituted pyrrole-fused isocoumarins under solvent-free conditions

    PubMed Central

    Pathak, Sudipta; Debnath, Kamalesh

    2013-01-01

    Summary A convenient and efficient methodology for the synthesis of densely substituted pyrrole-fused isocoumarins, which employs solid-supported silica sulfuric acid (SSA) as catalyst, has been developed. When the mixture of ninhydrin adducts of acetylacetone/ethyl acetoacetate and primary amines was heated on the solid surface of SSA under solvent-free conditions, the pyrrole-fused isocoumarins were formed in good yields. This synthetic method has several advantages such as the employment of solvent-free reaction conditions without the use of any toxic reagents and metal catalysts, the ease of product isolation, the use of a recyclable catalyst, the low cost, the easy availability of the starting materials, and the excellent yields of products. PMID:24367398

  6. Fabrication and characterization of a silicon cantilever probe with an integrated quartz-glass (fused-silica) tip for scanning near-field optical microscopy.

    PubMed

    Schürmann, G; Noell, W; Staufer, U; de Rooij, N F; Eckert, R; Freyland, J M; Heinzelmann, H

    2001-10-01

    A cantilever-based probe is introduced for use in scanning near-field optical microscopy (SNOM) combined with scanning atomic-force microscopy (AFM). The probes consist of silicon cantilevers with integrated 25-mum-high fused-silica tips. The probes are batch fabricated by microfabrication technology. Transmission electron microscopy reveals that the transparent quartz tips are completely covered with an opaque aluminum layer before the SNOM measurement. Static and dynamic AFM imaging was performed. SNOM imaging in transmission mode of single fluorescent molecules shows an optical resolution better than 32 nm.

  7. Formation of a plano-convex micro-lens array in fused silica glass by using a CO2 laser-assisted reshaping technique

    NASA Astrophysics Data System (ADS)

    Sohn, Ik-Bu; Yoo, Dongyoon; Noh, Young-Chul; Sung, Jae-Hee; Lee, Seong-Ku; Choi, Hun-Kook; Ahsan, Md. Shamim

    2016-08-01

    We report on fabricating high-fill-factor plano-convex spherical and square micro-lens arrays on fused silica glass surface by using a CO2 laser-assisted reshaping technique. Initially, periodic micro-pillars are encoded on glass surfaces by means of a femtosecond laser beam, afterwards, the micro-pillars are polished several times by irradiating a CO2 laser beam on top of the micro-pillars. Consequently, a spherical micro-lens array with micro-lens size of 50 μm × 50 μm and a square micro-lens array with micro-lens size of 100 μm × 100 μm are formed on the surface of the fused silica glass. We also study the intensity distribution of light passing through the glass sample engraved with a spherical micro-lens array. The simulation result shows that the focal length of the spherical micro-lens array is 35 μm. Furthermore, we investigate the optical properties of glass samples with engraved micro-lens arrays. The proposed CO2-laser-based reshaping technique is simple and fast and shows promises for fabricating arrays of smooth micro-lenses in various transparent materials.

  8. Comparison of three modifications of fused-silica capillaries and untreated capillaries for protein profiling of maize extracts by capillary electrophoresis.

    PubMed

    Pobozy, Ewa; Sentkowska, Aleksandra; Piskor, Anna

    2014-09-01

    In this work, capillary electrophoresis was applied to protein profiling of fractionated extracts of maize. A comparative study on the application of uncoated fused-silica capillaries and capillaries modified with hydroxypropylmethylcellulose, ω-iodoalkylammonium salt and a commercially available neutral capillary covalently coated with polyacrylamide is presented. The coating stability, background electrolyte composition, and separation efficiency were investigated. It was found that for zeins separation, the most stable and efficient was the capillary coated with polyacrylamide. Finally, the usefulness of these methods was studied for the differentiation of zein fraction in transgenic and nontransgenic maize. Zeins extracted from maize standards containing 0 and 5% m/m genetic modification were successfully separated, but slight differences were observed in terms of the zein content. Albumin and globulin fractions were analyzed with the use of unmodified fused-silica capillary with borate buffer pH 9 and the capillary coated with polyacrylamide with phosphate buffer pH 3. In the albumin fraction, additional peaks were found in genetically modified samples.

  9. Separation of iron-free and iron-saturated forms of transferrin and lactoferrin via capillary electrophoresis performed in fused-silica and neutral capillaries.

    PubMed

    Nowak, Paweł; Śpiewak, Klaudyna; Brindell, Małgorzata; Woźniakiewicz, Michał; Stochel, Grażyna; Kościelniak, Paweł

    2013-12-20

    A capillary electrophoresis-based method for the cost-effective and high efficient separation of iron-free and iron-saturated forms of two members of transferrin family: transferrin and lactoferrin has been developed. The proposed qualitative method relying on the SDS application allowed us to separate iron-free and iron-saturated forms of these proteins, as well as human serum albumin, used as an internal standard. Owing to the distinct migration times under established conditions, the combination of transferrin and lactoferrin assays within a single analytical procedure was feasible. The performance of the method using a fused-silica capillary has been compared with the results obtained using the same method but performed with the use of a neutral capillary of the same dimensions. Neutral capillary has been used as an alternative, since the comparable resolution has been achieved with a concomitant reduction of the electroosmotic flow. Despite of this fact, the migration of analytes occurred with similar velocity but in opposite order, due to the reverse polarity application. A quantitative method employing fused-silica capillary for iron saturation study has been also developed, to evaluate the iron saturation in commercial preparations of lactoferrin.

  10. Effect of preannealing on the level of second-harmonic generation and defect sites achieved in poled low-water fused silica

    NASA Astrophysics Data System (ADS)

    Henry, Leanne J.; Devilbiss, Alan D.; Tsai, Tsung E.

    1995-11-01

    The level of second-harmonic generation (SHG) in poled low-water fused silica was altered by preannealing in aqueous and dry-nitrogen atmospheres. The effect of water and heat was found to depend on the lot from which the material originated. The effect on the SHG of either a wet or a dry preanneal was sometimes found to be reversible by the opposite preannealing process. For both wet and dry preannealed samples the SHG was found to have both near-surface (< 25- mu m) and bulk ( \\approximately 1.5-mm) components. Electron paramagnetic resonance (EPR) data revealed the presence of Si and Ge E\\prime defect sites and showed that the relative concentrations of these sites was altered by the preannealing processes. EPR and SHG data provided evidence for a second-order bond effect along with a third-order hole-filling effect as sources of the nonlinearity. Copyright (c) 1995 Optical Society of America

  11. The effect of pulse duration on the growth rate of laser-induced damage sites at 351 nm on fused silica surfaces

    SciTech Connect

    Negres, R A; Norton, M A; Liao, Z M; Cross, D A; Bude, J D; Carr, C W

    2009-10-29

    Past work in the area of laser-induced damage growth has shown growth rates to be primarily dependent on the laser fluence and wavelength. More recent studies suggest that growth rate, similar to the damage initiation process, is affected by a number of additional parameters including pulse duration, pulse shape, site size, and internal structure. In this study, we focus on the effect of pulse duration on the growth rate of laser damage sites located on the exit surface of fused silica optics. Our results demonstrate, for the first time, a significant dependence of growth rate at 351 nm on pulse duration from 1 ns to 15 ns as {tau}{sup 0.3} for sites in the 50-100 {micro}m size range.

  12. Correlation between laser-induced damage densities of fused silica and average incubation fluences at 1064 nm in the nanosecond regime

    NASA Astrophysics Data System (ADS)

    Lamaignère, L.; Diaz, R.; Chambonneau, M.; Grua, P.; Natoli, J.-Y.; Rullier, J.-L.

    2017-01-01

    The chronology of the physical processes involved in the nanosecond laser damage of fused silica is investigated at 1064 nm. From experiments realized with multiple longitudinal mode pulses, the correspondence between ring pattern damage morphology and the corresponding intensity profile allows the distinction of two damage phases: an incubation phase followed by a damage expansion phase that leads to the final damage diameter. It allows us to determine both the incubation and the expansion fluences. These results are compared to damage density measurements for different laser configurations, different optics, and different environments. It was found that damage densities were as high as incubation fluences were low. This approach shows a deterministic part of laser damage in nanosecond regime and contributes to reinforce the statistical results by reducing their random nature and is more able to guide the physical interpretations of laser damage experiments.

  13. High-efficiency reflective diffraction gratings in fused silica as (de)multiplexers at 1.55 μm for dense wavelength division multiplexing application

    NASA Astrophysics Data System (ADS)

    Zhang, Yanyan; Zhou, Changhe

    2005-02-01

    We describe high-efficiency, high-dispersion reflection gratings fabricated in bulk fused silica illuminated by incident lights in the C+L bands as (de)multiplexers for dense wavelength division multiplexing (DWDM) application. Based on the phenomenon of total internal reflection, gratings with optimized profile parameters exhibit diffraction efficiencies of more than 90% under TM- and TE-polarized incident lights for 101-nm spectral bandwidths (1520-1620 nm) and can reach an efficiency of greater than 97% for both polarizations at a wavelength of 1550 nm. Without loss of metal absorption, without coating of dielectric film layers, and independent of tooth shape, this new kind of grating should be of great interest for DWDM application.

  14. Influence of fused Silica and chills incorporation on Corrosion, Thermal and Chemical composition of ASTM A 494 M Grade Nickel alloy

    NASA Astrophysics Data System (ADS)

    Purushotham, G.; Hemanth, Joel

    2016-09-01

    A review of a host of relevant literature on the composites leads to some important observations on the gap that prevails for developing the composite with increased strength to weight ratio, improved thermal properties and reduced corrosion rate with the addition of fused SiO2 dispersoid for the nickel based alloy. In the arena of engineering, metallurgists look for techniques to improve the thermal, corrosion and chemical properties of the materials. In this connection an investigation has been carried out to fabricate and evaluate the corrosion, chemical and thermal properties of chilled composites consisting of nickel matrix with fused silica particles (size 40-150 μm) in the matrix. The main objective of the present research is to obtain fine grain Ni/SiO2 chilled sound composite having very good properties. The dispersoid added ranged from 3 to 12 wt. % in steps of 3%. The subsequent composites cast in molds containing metallic and non-metallic chill blocks (MS, SiC & Cu) were tested for their microstructure, chemical, thermal properties and corrosion behavior.

  15. Cryogenic surface distortion and hysteresis of a 50 cm diameter fused silica mirror cooled to 77 K

    NASA Technical Reports Server (NTRS)

    Young, Jeffrey A.; Howard, Steven D.; Augason, Gordon C.; Melugin, Ramsey K.

    1990-01-01

    A 50 cm diameter, lightweight, Amersil TO8E, fused-natural-quartz mirror with a single arch cross section was tested at the NASA/Ames Research Center Cryogenic Optics Test Facility to measure cryogenic distortion and hysteresis. The mirror was cooled to 77 K in four serial tests and the mirror figure was measured with a phase-measuring interferometer. On the basis of the repeatability of room temperature and cryogenic optical measurements, it was determined that the Single Arch Mirror had no measurable hysteresis and displayed repeatable cryogenic distortion. The Cryogenic Optics Test Facility, optical and thermal test methods, test results, and measurement accuracy are described.

  16. Raman spectroscopic measurements of CO2 density: Experimental calibration with high-pressure optical cell (HPOC) and fused silica capillary capsule (FSCC) with application to fluid inclusion observations

    USGS Publications Warehouse

    Wang, X.; Chou, I.-Ming; Hu, W.; Burruss, R.C.; Sun, Q.; Song, Y.

    2011-01-01

    Raman spectroscopy is a powerful method for the determination of CO2 densities in fluid inclusions, especially for those with small size and/or low fluid density. The relationship between CO2 Fermi diad split (??, cm-1) and CO2 density (??, g/cm3) has been documented by several previous studies. However, significant discrepancies exist among these studies mainly because of inconsistent calibration procedures and lack of measurements for CO2 fluids having densities between 0.21 and 0.75g/cm3, where liquid and vapor phases coexist near room temperature.In this study, a high-pressure optical cell and fused silica capillary capsules were used to prepare pure CO2 samples with densities between 0.0472 and 1.0060g/cm3. The measured CO2 Fermi diad splits were calibrated with two well established Raman bands of benzonitrile at 1192.6 and 1598.9cm-1. The relationship between the CO2 Fermi diad split and density can be represented by: ??=47513.64243-1374.824414????+13.25586152????2-0.04258891551????3 (r2=0.99835, ??=0.0253g/cm3), and this relationship was tested by synthetic fluid inclusions and natural CO2-rich fluid inclusions. The effects of temperature and the presence of H2O and CH4 on this relationship were also examined. ?? 2011 Elsevier Ltd.

  17. Fiber-based solid phase microextraction using fused silica lined bottles to collect, store, and stabilize a multianalyte headspace gas sample for offline analyses.

    PubMed

    Harvey, Chris A; Carter, J Chance; Ertel, John R; Alviso, Cindy T; Chinn, Sarah C; Maxwell, Robert S

    2015-07-03

    We have developed a solid phase microextraction (SPME) sampling method using fused silica lined bottles (400 ml) to collect, store, and stabilize a headspace subsample from the source for subsequent offline, repetitive analyses of the gas using fiber-based SPME. The method enables long-term stability for repeated offline analysis of the organic species collected from the source headspace and retains all the advantages of fiber SPME sampling (e.g. rapid extraction, solvent free, simple and inexpensive) while providing additional advantages. Typically, the analytes collected on the SPME fiber must be desorbed and analyzed immediately to mitigate analyte loss or contamination. The new SPME sampling method, conducted offline using carboxen/polydimethylsiloxane (carboxen/PDMS - 85 μm) coated fibers, has been shown to be identical to in situ SPME sampling of a headspace acquired from an 80 component organic matrix with reproducibility demonstrated to be less than %RSD=7.0% for replicate samples measured over a 30-day period. In addition, repetitive samplings from one headspace aliquot are possible using one or more fibers and fiber types as well as quantitative options such as internal standard addition as demonstrated in a feasibility study using a benzene/toluene/xylene (BTX; 1 ppmv) certified gas standard, in which the SPME measurement precision (%RSD) was improved by a factor of 1.5-1.9 compared to the use of an external standard.

  18. Optical evaluation of digital micromirror devices (DMDs) with UV-grade fused silica, sapphire, and magnesium fluoride windows and long-term reflectance of bare devices

    NASA Astrophysics Data System (ADS)

    Quijada, Manuel A.; Travinsky, Anton; Vorobiev, Dmitry; Ninkov, Zoran; Raisanen, Alan; Robberto, Massimo; Heap, Sara

    2016-07-01

    Digital micromirror devices (DMDs) are commercial micro-electromechanical systems, consisting of millions of mirrors which can be individually addressed and tilted into one of two states (+/-12°). These devices were developed to create binary patterns in video projectors, in the visible range. Commercially available DMDs are hermetically sealed and extremely reliable. Recently, DMDs have been identified as an alternative to microshutter arrays for space-based multi-object spectrometers (MOS). Specifically, the MOS at the heart of the proposed Galactic Evolution Spectroscopic Explorer (GESE) uses the DMD as a reprogrammable slit mask. Unfortunately, the protective borosilicate windows limit the use of DMDs in the UV and IR regimes, where the glass has insufficient throughput. In this work, we present our efforts to replace standard DMD windows with custom windows made from UV-grade fused silica, low-absorption optical sapphire (LAOS) and magnesium fluoride (MgF2). We present transmission measurements of the antireflection coated windows and the reflectance of bare (window removed) DMDs. Furthermore, we investigated the long-term stability of the DMD reflectance and experiments for coating DMD active area with a layer of pure aluminum (Al) to boost reflectance performance in the UV spectral range (200-400 nm).

  19. Fused-core silica column ultra performance liquid chromatography – ion trap tandem mass spectrometry for determination of global DNA methylation status1

    PubMed Central

    Yang, Ill; Fortin, Marie C.; Richardson, Jason R.; Buckley, Brian

    2010-01-01

    Epigenetic modifications, such as DNA methylation, play key roles in transcriptional regulation of gene expression. More recently, global DNA methylation levels have been documented to be altered in several diseases, including cancer, and as the result of exposure to environmental toxicants. Based on the potential use of global DNA methylation status as a biomarker of disease status and exposure to environmental toxicants, we sought to develop a rapid, sensitive, and precise analytical method for the quantitative measurement of global DNA methylation status using ultra performance liquid chromatography with detection by ion trap tandem mass spectrometry. Using a fused-core silica column, 2′-deoxyguanosine (2dG) and 5-methyl-2′-deoxycytidine (5mdC) were resolved in less than 1 minute, with detection limits of 0.54 and 1.47 fmol for 5mdC and 2dG respectively. The accuracy of detection was 95% or above and the day-to-day coefficient of variations was found to be 3.8%. The method was validated by quantification of global DNA methylation status following treatment of cells with the DNA methyltransferase inhibitor 5-aza-2′deoxycytidine, which reduced DNA methylation from 3.1% in control cells to 1.1% in treated cells. The sensitivity and high throughput of this method rend it suitable for large scale analysis of epidemiological or clinical DNA samples. PMID:20950581

  20. Characterization of the atmospheric pressure ionization mass spectrometric process obtained using a fused-silica emitter with the high voltage applied upstream

    PubMed

    Sjoberg; Nyholm; Markides

    2000-03-01

    The atmospheric pressure ionization process obtained when a mixture of methanol and water (90:10, v/v) also containing 50 microM sodium hydroxide is dispersed from a fused-silica emitter was studied. A combination of a high electric field and a nebulizer gas with the high voltage applied upstream in the liquid flow was utilized to facilitate the spray process. By comparing the dependences of the spray current and ion signals on the spray potential, it was found that electrical corona discharges were obtained for potentials higher than about 2.6 kV, which resulted in a mixed electrospray and chemical ionization process. By introducing vapour from a solvent, such as benzene or toluene, with a low ionization energy into the nebulizing gas, it was found that the appearance of the corresponding molecular ion was correlated with a change in the slope of the spray current-potential curve. This indicates that the breakpoints in the spray current-potential curves observed were correlated with the onsets of corona discharges. It was shown that the mixed ionization process gives rise to increased amounts of protonated solvent molecules and assists in the formation of sodiated adduct ions from an uncharged fatty acid methyl ester.

  1. Optical Evaluation of Digital Micromirror Devices (DMDs) with UV-Grade Fused Silica, Sapphire, and Magnesium Fluoride Windows and Longterm Reflectance of Bare Devices

    NASA Technical Reports Server (NTRS)

    Quijada, Manuel A.; Travinsky, Anton; Vorobiev, Dmitry; Ninkov, Zoran; Raisanen, Alan; Robberto, Massimo; Heap, Sara

    2016-01-01

    Digital micromirror devices (DMDs) are commercial micro-electromechanical systems, consisting of millions of mirrors which can be individually addressed and tilted into one of two states (+/-12deg). These devices were developed to create binary patterns in video projectors, in the visible range. Commercially available DMDs are hermetically sealed and extremely reliable. Recently, DMDs have been identified as an alternative to microshutter arrays for space-based multi-object spectrometers (MOS). Specifically, the MOS at the heart of the proposed Galactic Evolution Spectroscopic Explorer (GESE) uses the DMD as a reprogrammable slit mask. Unfortunately, the protective borosilicate windows limit the use of DMDs in the UV and IR regimes, where the glass has insufficient throughput. In this work, we present our efforts to replace standard DMD windows with custom windows made from UV-grade fused silica, low-absorption optical sapphire (LAOS) and magnesium fluoride (MgF2). We present transmission measurements of the antireflection coated windows and the reflectance of bare (window removed) DMDs. Furthermore, we investigated the long-term stability of the DMD reflectance and experiments for coating DMD active area with a layer of pure aluminum (Al) to boost reflectance performance in the UV spectral range (200-400 nm).

  2. High-Speed Photographic Study of Wave Propagation and Impact Damage in Fused Silica and AlON Using the Edge-On Impact (EOI) Method

    SciTech Connect

    Strassburger, E.; Patel, P.; McCauley, J. W.; Templeton, D. W.

    2006-07-28

    An Edge-on Impact (EOI) technique, developed at the Ernst-Mach-Institute (EMI), coupled with a Cranz-Schardin high-speed camera, has been successfully utilized to visualize dynamic fracture in many brittle materials. In a typical test, the projectile strikes one edge of a specimen and damage formation and fracture propagation is recorded during the first 20 {mu}s after impact. In the present study, stress waves and damage propagation in fused silica and AlON were examined by means of two modified Edge-on Impact arrangements. In one arrangement, fracture propagation was observed simultaneously in side and top views of the specimens by means of two Cranz-Schardin cameras. In another arrangement, the photographic technique was modified by placing the specimen between crossed polarizers and using the photo-elastic effect to visualize the stress waves. Pairs of impact tests at approximately equivalent velocities were carried out in transmitted plane (shadowgraphs) and crossed polarized light.

  3. High-Speed Photographic Study of Wave Propagation and Impact Damage in Fused Silica and AlON Using the Edge-On Impact (EOI) Method

    NASA Astrophysics Data System (ADS)

    Strassburger, E.; Patel, P.; McCauley, J. W.; Templeton, D. W.

    2006-07-01

    An Edge-on Impact (EOI) technique, developed at the Ernst-Mach-Institute (EMI), coupled with a Cranz-Schardin high-speed camera, has been successfully utilized to visualize dynamic fracture in many brittle materials. In a typical test, the projectile strikes one edge of a specimen and damage formation and fracture propagation is recorded during the first 20 μs after impact. In the present study, stress waves and damage propagation in fused silica and AlON were examined by means of two modified Edge-on Impact arrangements. In one arrangement, fracture propagation was observed simultaneously in side and top views of the specimens by means of two Cranz-Schardin cameras. In another arrangement, the photographic technique was modified by placing the specimen between crossed polarizers and using the photo-elastic effect to visualize the stress waves. Pairs of impact tests at approximately equivalent velocities were carried out in transmitted plane (shadowgraphs) and crossed polarized light.

  4. High-speed Photographic Study of Wave Propagation and Impact Damage in Fused Silica and AlON Using the Edge-on Impact (EOI) Method

    NASA Astrophysics Data System (ADS)

    Patel, Parimal; Strassburger, Elmar; Templeton, Douglas

    2005-07-01

    An Edge-on Impact (EOI) test method coupled with a high speed Cranz-Schardin camera has been developed at the Fraunhofer-Institute for High-Speed Dynamics, Ernst-Mach-Institut (EMI), Efringen-Kirchen, Germany to visualize damage propagation and dynamic fracture in structural ceramics. Most work in the past has been carried out in a reflection mode from the surface of impacted ceramics. In the current study, the test was reconfigured to photograph the propagation of damage in the transmission mode using shadowgraphs. In addition to plain light observations, the stress wave was also visualized in crossed polarizers using the photoelastic effect. Plates of fused silica measuring 100X100X13mm were impacted at velocities from 151 to 350 m/s. Plates of AlON measuring 100X100X10mm were impacted using solid cylinder steel projectiles with velocities ranging from 270 to 925 m/s. Detailed analysis of the macroscopic fracture patterns, stress wave characteristics and velocity, various damage zones structures, single crack and crack front velocities will be presented.

  5. Change in transmittance of fused silica as a means of detecting material sputtered from components on a 5-cm ion thruster

    NASA Technical Reports Server (NTRS)

    Weigand, A. J.; Mirtich, M. J.

    1972-01-01

    Two endurance tests of a 5-cm mercury bombardment thruster are reported. Both tests used a translational screen-grid system with the beam vectored 10 degrees. The first test lasted 141 hours and the second test operated for 2026 hours. In each test two fused silica samples (solar cell covers), 2.0 cm by 2.1 cm, were placed in shielded holders to detect materials sputtered from the thruster. Spectral optical properties between 0.398 and 2.16 microns were measured on each sample, both before and after the endurance tests. The deposition on each sample was spectrographically analyzed to determine the type of materials sputtered from the thruster. It was found that sputtering from the neutralizer is highly dependent on its position with respect to the beam edge. The sputtering from the accelerator grid of the translational screen-grid system of the 2026 hour test was sufficient to form an opaque film on the sample located in the direction opposite to the vectored beam.

  6. FY07 LDRD Final Report A Fracture Mechanics and Tribology Approach to Understanding Subsurface Damage on Fused Silica during Grinding and Polishing

    SciTech Connect

    Suratwala, T I; Miller, P E; Menapace, J A; Wong, L L; Steele, R A; Feit, M D; Davis, P J; Walmer, C D

    2008-02-05

    The objective of this work is to develop a solid scientific understanding of the creation and characteristics of surface fractures formed during the grinding and polishing of brittle materials, specifically glass. In this study, we have experimentally characterized the morphology, number density, and depth distribution of various surface cracks as a function of various grinding and polishing processes (blanchard, fixed abrasive grinding, loose abrasive, pitch polishing and pad polishing). Also, the effects of load, abrasive particle (size, distribution, foreign particles, geometry, velocity), and lap material (pitch, pad) were examined. The resulting data were evaluated in terms of indentation fracture mechanics and tribological interactions (science of interacting surfaces) leading to several models to explain crack distribution behavior of ground surfaces and to explain the characteristics of scratches formed during polishing. This project has greatly advanced the scientific knowledge of microscopic mechanical damage occurring during grinding and polishing and has been of general interest. This knowledge-base has also enabled the design and optimization of surface finishing processes to create optical surfaces with far superior laser damage resistance. There are five major areas of scientific progress as a result of this LDRD. They are listed in Figure 1 and described briefly in this summary below. The details of this work are summarized through a number of published manuscripts which are included this LDRD Final Report. In the first area of grinding, we developed a technique to quantitatively and statistically measure the depth distribution of surface fractures (i.e., subsurface damage) in fused silica as function of various grinding processes using mixtures of various abrasive particles size distributions. The observed crack distributions were explained using a model that extended known, single brittle indentation models to an ensemble of loaded, sliding

  7. Optical and structural properties of polycrystalline CVD diamond films grown on fused silica optical fibres pre-treated by high-power sonication seeding

    NASA Astrophysics Data System (ADS)

    Bogdanowicz, R.; Śmietana, M.; Gnyba, M.; Gołunski, Ł.; Ryl, J.; Gardas, M.

    2014-09-01

    In this paper, the growth of polycrystalline chemical vapour deposition (CVD) diamond thin films on fused silica optical fibres has been investigated. The research results show that the effective substrate seeding process can lower defect nucleation, and it simultaneously increases surface encapsulation. However, the growth process on glass requires high seeding density. The effects of suspension type and ultrasonic power were the specific objects of investigation. In order to increase the diamond density, glass substrates were seeded using a high-power sonication process. The highest applied power of sonotrode reached 72 W during the performed experiments. The two, most common diamond seeding suspensions were used, i.e. detonation nanodiamond dispersed in (a) dimethyl sulfoxide and (b) deionised water. The CVD diamond nucleation and growth processes were performed using microwave plasma assisted chemical vapour deposition system. Next, the seeding efficiency was determined and compared using the numerical analysis of scanning electron microscopy images. The molecular composition of nucleated diamond was examined with micro-Raman spectroscopy. The sp3/sp2 band ratio was calculated using Raman spectra deconvolution method. Thickness, roughness, and optical properties of the nanodiamond films in UV-vis wavelength range were investigated by means of spectroscopic ellipsometry. It has been demonstrated that the high-power sonication process can improve the seeding efficiency on glass substrates. However, it can also cause significant erosion defects at the fibre surface. We believe that the proposed growth method can be effectively applied to manufacture the novel optical fibre sensors. Due to high chemical and mechanical resistance of CVD diamond films, deposition of such films on the sensors is highly desirable. This method enables omitting the deposition of an additional adhesion interlayer at the glass-nanocrystalline interface, and thus potentially increases

  8. Fused silica capillaries with two segments of different internal diameters and inner surface roughnesses prepared by etching with supercritical water and used for volume coupling electrophoresis.

    PubMed

    Horká, Marie; Karásek, Pavel; Roth, Michal; Šlais, Karel

    2017-02-22

    In this work, single-piece fused silica capillaries with two different internal diameter segments featuring different inner surface roughness were prepared by new etching technology with supercritical water and used for volume coupling electrophoresis. The concept of separation and online pre-concentration of analytes in high conductivity matrix is based on the online large-volume sample pre-concentration by the combination of transient isotachophoretic stacking and sweeping of charged proteins in micellar electrokinetic chromatography using non-ionogenic surfactant. The modified surface roughness step helped to the significant narrowing of the zones of examined analytes. The sweeping and separating steps were accomplished simultaneously by the use of phosphate buffer (pH 7) containing ethanol, non-ionogenic surfactant Brij 35, and polyethylene glycol (PEG 10000) after sample injection. Sample solution of a large volume (maximum 3.7 μL) dissolved in physiological saline solution was injected into the wider end of capillary with inlet inner diameter from 150, 185 or 218 μm. The calibration plots were linear (R(2) ∼ 0.9993) over a 0.060-1 μg/mL range for the proteins used, albumin and cytochrome c. The peak area RSDs from at least 20 independent measuremens were below 3.2%. This online pre-concentration technique produced a more than 196-fold increase in sensitivity, and it can be applied for detection of, e.g. the presence of albumin in urine (0.060 μg/mL).

  9. Blow-Out Velocities of Solutions of Hydrocarbons and Boron Hydride - Hydrocarbon Reaction Products in a 1 7/8-Inch-Diameter Combustor

    NASA Technical Reports Server (NTRS)

    Morris, James F.; Lord, Albert M.

    1957-01-01

    Blow-out velocities were determined for JP-4 solutions containing: (1) 10 % ethylene - decaborane reaction product, (2) 10% and 20% acetylene - diborane reaction product, and (3) 5.5%, 15.7%, and 30.7% methylacetylene - diborane reaction product. These were compared with blow-out velocities for JP-4, propylene oxide, and neohexane and previously reported data for JP-4 solutions of pentaborane. For those reaction products investigated, the blow-out velocities at a fixed equivalence ratio were higher for those materials containing higher boron concentrations; that is, blow-out velocity increased in the following order: (1) methylacetylene - diborane, (2) acetylene - diborane, and (3) ethylene - decaborane reaction products.

  10. Boron doped Si rich oxide/SiO{sub 2} and silicon rich nitride/SiN{sub x} bilayers on molybdenum-fused silica substrates for vertically structured Si quantum dot solar cells

    SciTech Connect

    Lin, Ziyun Wu, Lingfeng; Jia, Xuguang; Zhang, Tian; Puthen-Veettil, Binesh; Yang, Terry Chien-Jen; Conibeer, Gavin; Perez-Wurfl, Ivan

    2015-07-28

    Vertically structured Si quantum dots (QDs) solar cells with molybdenum (Mo) interlayer on quartz substrates would overcome current crowding effects found in mesa-structured cells. This study investigates the compatibility between boron (B) doped Si QDs bilayers and Mo-fused silica substrate. Both Si/SiO{sub 2} and Si/SiN{sub x} based QDs bilayers were studied. The material compatibility under high temperature treatment was assessed by examining Si crystallinity, microstress, thin film adhesion, and Mo oxidation. It was observed that the presence of Mo interlayer enhanced the Si QDs size confinement, crystalline fraction, and QDs size uniformity. The use of B doping was preferred compared to phosphine (PH{sub 3}) doping studied previously in terms of better surface and interface properties by reducing oxidized spots on the film. Though crack formation due to thermal mismatch after annealing remained, methods to overcome this problem were proposed in this paper. Schematic diagram to fabricate full vertical structured Si QDs solar cells was also suggested.

  11. Capillary isoelectric focusing of probiotic bacteria from cow's milk in tapered fused silica capillary with off-line matrix-assisted laser desorption/ionization time-of-flight mass spectrometry identification.

    PubMed

    Horká, Marie; Karásek, Pavel; Salplachta, Jiří; Růžička, Filip; Vykydalová, Marie; Kubesová, Anna; Dráb, Vladimír; Roth, Michal; Slais, Karel

    2013-07-25

    In this study, combination of capillary isoelectric focusing (CIEF) in tapered fused silica (FS) capillary with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is presented as an efficient approach for unambiguous identification of probiotic bacteria in real sample. For this purpose, bacteria within genus Lactobacillus were selected as model bioanalytes and cow's milk was selected as a biological sample. CIEF analysis of both the cultivated bacteria and the bacteria in the milk was optimized and isoelectric points characterizing the examined bacteria were subsequently determined independently of the bacterial sample origin. The use of tapered FS capillary significantly enhanced the separation capacity and efficiency of the CIEF analyses performed. In addition, the cell number injected into the tapered FS capillary was quantified and an excellent linearity of the calibration curves was achieved which enabled quantitative analysis of the bacteria by CIEF with UV detection. The minimum detectable number of bacterial cells was 2×10(6) mL(-1). Finally, cow's milk spiked with the selected bacterium was analyzed by CIEF in tapered FS capillary, the focused and detected bacterial cells were collected from the capillary, deposited onto the cultivation medium, and identified using MALDI-TOF MS afterward. Our results have revealed that the proposed procedure can be advantageously used for unambiguous identification of probiotic bacteria in a real sample.

  12. Co-electroosmotic capillary electrophoresis of basic proteins with 1-alkyl-3-methylimidazolium tetrafluoroborate ionic liquids as non-covalent coating agents of the fused-silica capillary and additives of the electrolyte solution.

    PubMed

    Corradini, Danilo; Nicoletti, Isabella; Bonn, Günther K

    2009-06-01

    The paper reports the results of a study carried out to evaluate the use of three 1-alkyl-3-methylimidazolium-based ionic liquids as non-covalent coating agents for bare fused-silica capillaries and additives of the electrolyte solutions (BGE) for CE of basic proteins in the co-EOF separation mode. The three ionic liquids are differentiated from each other by the length of the alkyl group on the imidazolium cation, consisting of either an ethyl, butyl or octyl substituent, whereas tetrafluoroborate is the common anionic component of the ionic liquids. Coating the capillary with the ionic liquid resulted in improved peak shape and protein separation, while the EOF was maintained cathodic. This indicates that each ionic liquid is effective at masking the protein interaction sites on the inner surface of the capillary, also when its adsorption onto the capillary wall has not completely neutralized all the negative charges arising from the ionization of the silanol groups and the ionic liquid is not incorporated into the BGE employed for separation. Using the coated capillaries with BGE containing the ionic liquid employed for the coating, at concentration low enough to maintaining the EOF cathodic, both peak shape and protein separation varied to different extents, based on the particular ionic liquid used and its concentration. Fast and efficient separation of the model basic protein mixture in co-electroosmotic CE is obtained with the 1-butyl-3-methylimidazolium tetrafluoroborate coated capillary and 100 mM acetate buffer (pH 4.0) containing 4.4 mM 1-butyl-3-methylimidazolium tetrafluoroborate as the BGE.

  13. Schlieren Movies of the 8-Inch Diameter Rigid Parachute Model of the Cook Research Laboratory Taken During the Fourth Phase of Testing in the Langley Unitary Plan Wind Tunnel

    NASA Technical Reports Server (NTRS)

    1958-01-01

    Canopy Model IV was tested in four different configuration series. Shroud lines were used in the first three series of tests; none were used in the fourth series. Other variables were Mach number (1.77, 2.17, 2.76), dynamic pressure (290, 250, 155 lb per sq ft), camera speed, and attitude.

  14. Measurements of Heat Transfer and Boundary-Layer Transition on an 8-Inch-Diameter Hemisphere-Cylinder in Free Flight for a Mach Number Range of 2.00 to 3.88

    NASA Technical Reports Server (NTRS)

    Garland, Benjamine J.; Chauvin, Leo T.

    1957-01-01

    Measurements of aerodynamic heat transfer have been made along the hemisphere and cylinder of a hemisphere-cylinder rocket-propelled model in free flight up to a Mach number of 3.88. The test Reynolds number based on free-stream condition and diameter of model covered a range from 2.69 x l0(exp 6) to 11.70 x 10(exp 6). Laminar, transitional, and turbulent heat-transfer coefficients were obtained. The laminar data along the body agreed with laminar theory for blunt bodies whereas the turbulent data along the cylinder were consistently lower than that predicted by the turbulent theory for a flat plate. Measurements of heat transfer at the stagnation point were, in general, lower than the theory for stagnation-point heat transfer. When the Reynolds number to the junction of the hemisphere-cylinder was greater than 6 x l0(exp 6), the transitional Reynolds number varied from 0.8 x l0(exp 6) to 3.0 x 10(exp 6); however, than 6 x l(exp 6) when the Reynolds number to the junction was less, than the transitional Reynolds number varied from 7.0 x l0(exp 6) to 24.7 x 10(exp 6).

  15. Self-healing fuse development

    NASA Technical Reports Server (NTRS)

    Jones, N. D.; Kinsinger, R. E.; Harris, L. P.

    1973-01-01

    The mercury-filled self-healing fuses developed for this program afford very good protection from circuit faults with rapid reclosure. Fuse performance and design parameters have been characterized. Life tests indicate a capability of 500 fuse operations. Fuse ratings are 150 v at 5, 15, 25 and 50 circuit A. A series of sample fuses using alumina and beryllia insulation have been furnished to NASA for circuit evaluation.

  16. Novel synthesis of a series of spiro 1,3-indanedione-fused dihydropyridines through the condensation of a tetrone with N-aryl/alkylenamines in presence of solid support silica sulfuric acid.

    PubMed

    Kundu, Ashis; Pramanik, Animesh

    2015-08-01

    A convenient protocol for the library synthesis of biologically important 1-aryl-2',6-spiro(1',3'-indanedione)-1H-indeno[1,2-b]quinoline-5,7-diones has been developed. In this one-pot reaction protocol a tetrone is condensed with various N-aryl/alkylenamines of 1,3-cyclohexadiones on the surface of a solid-supported acid catalyst silica sulfuric acid under solvent-free condition. The significant advantages of this methodology are the use of solvent-free reaction conditions, operational simplicity of the reaction, good yield of the products with high atom economy, and employment of a recyclable catalyst. All these favorable factors make the present method convenient, economic, and 'benign by design'.

  17. OLED panel with fuses

    SciTech Connect

    Levermore, Levermore; Pang, Huiqing; Rajan, Kamala

    2014-09-16

    Embodiments may provide a first device that may comprise a substrate, a plurality of conductive bus lines disposed over the substrate, and a plurality of OLED circuit elements disposed on the substrate, where each of the OLED circuit elements comprises one and only one pixel electrically connected in series with a fuse. Each pixel may further comprise a first electrode, a second electrode, and an organic electroluminescent (EL) material disposed between the first and the second electrodes. The fuse of each of the plurality of OLED circuit elements may electrically connect each of the OLED circuit elements to at least one of the plurality of bus lines. Each of the plurality of bus lines may be electrically connected to a plurality of OLED circuit elements that are commonly addressable and at least two of the bus lines may be separately addressable.

  18. Method for fusing bone

    DOEpatents

    Mourant, Judith R.; Anderson, Gerhard D.; Bigio, Irving J.; Johnson, Tamara M.

    1996-01-01

    Method for fusing bone. The present invention is a method for joining hard tissue which includes chemically removing the mineral matrix from a thin layer of the surfaces to be joined, placing the two bones together, and heating the joint using electromagnetic radiation. The goal of the method is not to produce a full-strength weld of, for example, a cortical bone of the tibia, but rather to produce a weld of sufficient strength to hold the bone halves in registration while either external fixative devices are applied to stabilize the bone segments, or normal healing processes restore full strength to the tibia.

  19. Methods for Mitigating Growth of Laser-Initiated Surface Damage on Fused Silcia Optics at 351nm

    SciTech Connect

    Hrubesh, L W; Norton, M A; Molander, W A; Donohue, E E; Maricle, S M; Penetrante, B M; Brusasco, R M; Grundler, W; Butler, J A; Carr, J W; Hill, R M; Summers, L J; Feit, M D; Rubenchik, A; Key, M H; Wegner, P J; Burnham, A K; Hackel, L A; Kozlowski, M R

    2001-12-12

    We report a summary of the surface damage, growth mitigation effort at 351nm for polished fused silica optics. The objective was to experimentally validate selected methods that could be applied to pre-initiated or retrieved-from-service optics, to stop further damage growth. A specific goal was to obtain sufficient data and information on successful methods for fused silica optics to select a single approach for processing large aperture, fused-silica optics used in high-peak-power laser applications. This paper includes the test results and the evaluation thereof, for several mitigation methods for fused silica surfaces. The mitigation methods tested in this study are wet chemical etching, cold plasma etching, CW-CO{sub 2} laser processing, and micro-flame torch processing. We found that CW-CO{sub 2} laser processing produces the most significant and consistent results to halt laser-induced surface damage growth on fused silica. We recorded successful mitigation of the growth of laser-induced surface damage sites as large as 0.5mm diameter, for 1000 shots at 351nm and fluences in the range of 8 to 13J/cm{sup 2}, {approx}11ns pulse length. We obtained sufficient data for elimination of damage growth using CO{sub 2} laser processing on sub-aperture representative optics, to proceed with application to large aperture ({approx}40 x 40cm{sup 2}) fused silica.

  20. 1.2W laser amplification at 1427nm on the 4F3/2 to 4I13/2 spectral line in an Nd3+ doped fused silica optical fiber.

    PubMed

    Dawson, Jay W; Pax, Paul H; Allen, Graham S; Drachenberg, Derrek R; Khitrov, Victor V; Schenkel, Nick; Messerly, Michael J

    2016-12-12

    A 9.3dB improvement in optical gain and a 100x improvement in total optical power over prior published experimental results from the 4F3/2 to 4I13/2 transition in an Nd3+ doped fused silica optical fiber is demonstrated. This is enabled via an optical fiber waveguide design that creates high spectral attenuation in the 1050-1120nm-wavelength range, a continuous spectral filter for the primary 4F3/2 to 4I11/2 optical transition. A maximum output power at 1427nm of 1.2W was attained for 43mW coupled seed laser power and 22.2W of coupled pump diode laser power at 880nm a net optical gain of 14.5dB. Reducing the coupled seed laser power to 2.5mW enabled the system to attain 19.3dB of gain for 16.5W of coupled pump power. Four issues limited results; non-optimal seed laser wavelength, amplified spontaneous emission on the 4F3/2 to 4I9/2 optical transition, low absorption of pump light from the cladding and high spectral attenuation in the 1350-1450nm range. Future fibers that mitigate these issues should lead to significant improvements in the efficiency of the laser amplifier, though the shorter wavelength region of the transition from 1310nm to >1350nm is still expected to be limited by excited state absorption.

  1. Fused Lasso Additive Model

    PubMed Central

    Petersen, Ashley; Witten, Daniela; Simon, Noah

    2016-01-01

    We consider the problem of predicting an outcome variable using p covariates that are measured on n independent observations, in a setting in which additive, flexible, and interpretable fits are desired. We propose the fused lasso additive model (FLAM), in which each additive function is estimated to be piecewise constant with a small number of adaptively-chosen knots. FLAM is the solution to a convex optimization problem, for which a simple algorithm with guaranteed convergence to a global optimum is provided. FLAM is shown to be consistent in high dimensions, and an unbiased estimator of its degrees of freedom is proposed. We evaluate the performance of FLAM in a simulation study and on two data sets. Supplemental materials are available online, and the R package flam is available on CRAN. PMID:28239246

  2. The distribution of subsurface damage in fused silica

    SciTech Connect

    Miller, P E; Suratwala, T I; Wong, L L; Feit, M D; Menapace, J A; Davis, P J; Steele, R A

    2005-11-21

    Managing subsurface damage during the shaping process and removing subsurface damage during the polishing process is essential in the production of low damage density optical components, such as those required for use on high peak power lasers. Removal of subsurface damage, during the polishing process, requires polishing to a depth which is greater than the depth of the residual cracks present following the shaping process. To successfully manage, and ultimately remove subsurface damage, understanding the distribution and character of fractures in the subsurface region introduced during fabrication process is important. We have characterized the depth and morphology of subsurface fractures present following fixed abrasive and loose abrasive grinding processes. At shallow depths lateral cracks and an overlapping series of trailing indentation fractures were found to be present. At greater depths, subsurface damage consists of a series of trailing indentation fractures. The area density of trailing fractures changes as a function of depth, however the length and shape of individual cracks remain nearly constant for a given grinding process. We have developed and applied a model to interpret the depth and crack length distributions of subsurface surface damage in terms of key variables including abrasive size and load.

  3. Infrared spectra of silica polymorphs

    NASA Astrophysics Data System (ADS)

    Koike, C.; Noguchi, R.; Chihara, H.; Suto, H.; Ohtaka, O.; Imai, Y.; Matsumoto, T.; Tsuchiyama, A.

    The existence of silica within several debris disks has been suggested. We investigate the annealing conditions of α-cristobalite, and further prepare various types of silica, including α-cristobalite, α-quartz, coesite, stishovite, and fused quartz, which are natural, synthetic or commercial samples. We compare the results to previous studies and find that α-cristobalite synthesized at higher temperature than annealed silica. The interesting result of features similar to those of forsterite should be highlighted, where αcristobalite and coesite showed similar peaks at 16, 33, and 69 μm as forsterite. The 69 μm band for αcristobalite is especially very broad and strong, and shifts largely to a shorter wavelengths under cooling to low temperatures. The band for coesite, however, is very sharp, and shifts only a small amount to longer wavelengths under cooling to low temperatures. The peak positions of 16 and 69-μm band due to α-cristobalite can become index for temperature of silica dust. We discuss the possibility of silica detection around debris disks.

  4. Shock-wave processes evolution in fused quartz under intense energy action

    NASA Astrophysics Data System (ADS)

    Efremov, V. P.; Ivanov, M. F.; Kiverin, A. D.; Yakovenko, I. S.

    2016-11-01

    The paper considers gas-dynamical processes evolving as a result of laser action in fused quartz. A conventional approach is used to construct a model for equation of state which provides an adequate description of the silica state at high densities of energy typical for local optical silica damage. Shock-wave processes generated in the medium due to the local laser energy deposition are calculated using fully conservative numerical technique. The obtained results provide relatively accurate description of the process in a wide range of parameters and allow further research to get clear interpretation of high-speed propagation of the laser absorbing front through the silica optical fiber.

  5. Silica substrate or portion formed from oxidation of monocrystalline silicon

    DOEpatents

    Matzke, Carolyn M.; Rieger, Dennis J.; Ellis, Robert V.

    2003-07-15

    A method is disclosed for forming an inclusion-free silica substrate using a monocrystalline silicon substrate as the starting material and oxidizing the silicon substrate to convert it entirely to silica. The oxidation process is performed from both major surfaces of the silicon substrate using a conventional high-pressure oxidation system. The resulting product is an amorphous silica substrate which is expected to have superior etching characteristics for microfabrication than conventional fused silica substrates. The present invention can also be used to convert only a portion of a monocrystalline silicon substrate to silica by masking the silicon substrate and locally thinning a portion the silicon substrate prior to converting the silicon portion entirely to silica. In this case, the silica formed by oxidizing the thinned portion of the silicon substrate can be used, for example, as a window to provide optical access through the silicon substrate.

  6. Development of an improved toughness hyperpure silica reflective heat shield

    NASA Technical Reports Server (NTRS)

    Rusert, E. L.; Hackett, T. L.; Drennan, D. N.

    1979-01-01

    High purity three dimensionally woven silica-silica materials were evaluated for use as a tough reflective heat shield for planetary entry probes. A special weave design was selected to minimize light piping effects through the heat shield thickness. Various weave spacings were evaluated for densification efficiency with an 0.7 micron particle size high purity silica. Spectral hemispherical reflectance was measured from 0.2 to 2.5 microns at room temperature. Reflectance increases due to densification and purity of material were measured. Reflectance of 3D hyperpure silica was higher than 3D astroquartz silica for all wavelengths. Mechanical properties were measured in beam flexure and beam shear tests. Results indicated strengths lower than reported for slip cast fused silica. Low strengths were attributed to low densities achieved through vacuum impregnation.

  7. FUSE satellite electrical power subsystem

    SciTech Connect

    Roufberg, L.; Noah, K.

    1998-07-01

    The Far Ultraviolet Spectroscopic Explorer (FUSE) satellite will be placed into a low earth orbit to investigate astrophysical processes related to the formation and development of the early universe. The FUSE satellite is considered a pathfinder for NASA's Mid-Class Explorers (MIDEX). To reduce mission cost and development time while delivering quality science, NASA has enforced strict cost caps with a clear definition of high-level science objectives. As a result, a significant design driver for the electrical power subsystem (EPS) was to minimize cost. The FUSE EPS is a direct energy transfer, unregulated bus architecture, with batteries directly on the bus and solar array power limted by pulse-width-modulated shunt regulators. The power subsystem electronics (PSE) contains circuitry to control battery charging, provide power to the loads, and provide fault protection. The electronics is based on the PSE which Orbital (formerly, Fairchild Space) designed and built for NASA/GSFC's XTE spacecraft. However, the FUSE PSE design incorporates a number of unique features to meet the mission requirements. To minimize size of the solar panels due to stowed attachment constraints, GaAs/Ge solar cells were selected. This is the first time this type of large area, thinned solar cell with integral bypass diodes are being used for a NASA LEO mission. The solar panels support a satellite load power of 520W. Nickel Cadmium (NiCd) batteries are used which are identical to the RADARSAT-I design, except for different temperature sensors. This is the first mission for which Orbital is using SAFT NiCd batteries. The spacecraft bus, including the EPS, has successfully completed environmental testing and has been delivered for instrument integration. Tradeoffs involved in designing the EPS and selecting components based on the requirements are discussed. Analyses including solar array and battery sizing and energy balance are presented in addition to results from testing the flight

  8. 16 CFR 1507.3 - Fuses.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS FIREWORKS DEVICES § 1507.3 Fuses. (a) Fireworks devices that require a fuse shall: (1) Utilize only a fuse that has been... it will support either the weight of the fireworks device plus 8 ounces of dead weight or double...

  9. 16 CFR 1507.3 - Fuses.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS FIREWORKS DEVICES § 1507.3 Fuses. (a) Fireworks devices that require a fuse shall: (1) Utilize only a fuse that has been... it will support either the weight of the fireworks device plus 8 ounces of dead weight or double...

  10. 16 CFR 1507.3 - Fuses.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS FIREWORKS DEVICES § 1507.3 Fuses. (a) Fireworks devices that require a fuse shall: (1) Utilize only a fuse that has been... it will support either the weight of the fireworks device plus 8 ounces of dead weight or double...

  11. 16 CFR 1507.3 - Fuses.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS FIREWORKS DEVICES § 1507.3 Fuses. (a) Fireworks devices that require a fuse shall: (1) Utilize only a fuse that has been... it will support either the weight of the fireworks device plus 8 ounces of dead weight or double...

  12. 30 CFR 56.6502 - Safety fuse.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... purpose. Carbide lights, liquefied petroleum gas torches, and cigarette lighters shall not be used to light safety fuse. (h) At least two persons shall be present when lighting safety fuse, and no one shall light more than 15 individual fuses. If more than 15 holes per person are to be fired,...

  13. 30 CFR 57.6502 - Safety fuse.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... with devices designed for that purpose. Carbide lights, liquefied petroleum gas torches, and cigarette lighters shall not be used to light safety fuse. (h) At least two persons shall be present when lighting safety fuse, and no one shall light more than 15 individual fuses. If more than 15 holes per person...

  14. 30 CFR 28.2 - Approved fuses.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... MINING PRODUCTS FUSES FOR USE WITH DIRECT CURRENT IN PROVIDING SHORT-CIRCUIT PROTECTION FOR TRAILING CABLES IN COAL MINES General Provisions § 28.2 Approved fuses. (a) On and after the effective date of this part, fuses shall be considered to be approved for use with direct current in providing...

  15. Track of a fiber fuse: a Rayleigh instability in optical waveguides.

    PubMed

    Atkins, R M; Simpkins, P G; Yablon, A D

    2003-06-15

    The phenomenon colloquially known as a fiber fuse occurs when an optical fiber carrying high power is damaged or in some way abused. Beginning at the damage site a brilliant, highly visible plasmalike disturbance propagates back toward the optical source at speeds ranging from 0.3 to approximately 3 m/s, leaving in its wake a trail of bubbles and voids. We suggest that the bubble tracks in fused fibers are the result of a classic Rayleigh instability that is due to capillary effects in the molten silica that surrounds the vaporized fiber core. We report measurements of the bubble distribution and the collapse time that are consistent with this contention.

  16. Photochemical welding of silica optical components to silicone rubber by F2 laser

    NASA Astrophysics Data System (ADS)

    Okoshi, M.; Li, J.; Herman, P. R.; Inoue, N.

    2007-04-01

    Photochemical welding of fused silica glass to silicone rubber has been demonstrated by 157-nm F2 laser-induced photochemical modification of the silicone surface in contact with the glass. Fused-silica coverslips (150 m thick), silica optical fibres (125 µm diameter), and 2.9- µm diameter microspheres were successfully welded onto 2-mm-thick silicone rubber by irradiating the silicone surface through the partially transparent glasses. Sufficient photochemical conversion for strong welding was provided by multiple exposures of tens to thousands of pulses in a narrow optimized fluence window near ~6-mJ/cm2 per pulse.

  17. Hollow silica spheres: synthesis and mechanical properties.

    PubMed

    Zhang, Lijuan; D'Acunzi, Maria; Kappl, Michael; Auernhammer, Günter K; Vollmer, Doris; van Kats, Carlos M; van Blaaderen, Alfons

    2009-03-03

    Core-shell polystyrene-silica spheres with diameters of 800 nm and 1.9 microm were synthesized by soap-free emulsion and dispersion polymerization of the polystyrene core, respectively. The polystyrene spheres were used as templates for the synthesis of silica shells of tunable thickness employing the Stöber method [Graf et al. Langmuir 2003, 19, 6693]. The polystyrene template was removed by thermal decomposition at 500 degrees C, resulting in smooth silica shells of well-defined thickness (15-70 nm). The elastic response of these hollow spheres was probed by atomic force microscopy (AFM). A point load was applied to the particle surface through a sharp AFM tip, and successively increased until the shell broke. In agreement with the predictions of shell theory, for small deformations the deformation increased linearly with applied force. The Young's modulus (18 +/- 6 GPa) was about 4 times smaller than that of fused silica [Adachi and Sakka J. Mater. Sci. 1990, 25, 4732] but identical to that of bulk silica spheres (800 nm) synthesized by the Stöber method, indicating that it yields silica of lower density. The minimum force needed to irreversibly deform (buckle) the shell increased quadratically with shell thickness.

  18. Hybrid integrated PDMS microfluidics with a silica capillary.

    PubMed

    Dimov, Ivan K; Riaz, Asif; Ducrée, Jens; Lee, Luke P

    2010-06-07

    To harness the properties of both PDMS and silica, we have demonstrated hybrid integrated PDMS microfluidic systems with fused silica capillaries. The hybrid integrated PDMS microfluidics and silica capillary (iPSC) modules exhibit a novel architecture and method for leakage free CE sample injection merely requiring a single high voltage source and one pair of electrodes. The use of the iPSC device is based on a modular approach which allows the capillary to be reused extensively whilst replacing the attached fluidic module for different experiments. Integrating fused silica capillaries with PDMS microfluidic modules allows the direct application of a wide variety of well established conventional CE protocols for separations of complex analytes. Furthermore it bears the potential for facile coupling to standard electro-spray ionization mass spectrometry (ESI-MS), letting users focus on the sample analysis rather than the development of new separation protocols. The fabrication of the iPSC module consists of a simple and quick three-step method that submerges a fused silica capillary in PDMS prepolymer. After cross linking the prepolymer and punching the inlets, the iPSC module layer can be mounted onto a microfluidic device for CE separation.

  19. Silica suspension and coating developments for Advanced LIGO

    NASA Astrophysics Data System (ADS)

    Cagnoli, G.; Armandula, H.; Cantley, C. A.; Crooks, D. R. M.; Cumming, A.; Elliffe, E.; Fejer, M. M.; Gretarsson, A. M.; Harry, G. M.; Heptonstall, A.; Hough, J.; Jones, R.; Mackowski, J.-M.; Martin, I.; Murray, P.; Penn, S. D.; Perreur-Lloyd, M.; Reid, S.; Route, R.; Rowan, S.; Robertson, N. A. A.; Sneddon, P. H.; Strain, K. A.

    2006-03-01

    The proposed upgrade to the LIGO detectors to form the Advanced LIGO detector system is intended to incorporate a low thermal noise monolithic fused silica final stage test mass suspension based on developments of the GEO 600 suspension design. This will include fused silica suspension elements jointed to fused silica test mass substrates, to which dielectric mirror coatings are applied. The silica fibres used for GEO 600 were pulled using a Hydrogen-Oxygen flame system. This successful system has some limitations, however, that needed to be overcome for the more demanding suspensions required for Advanced LIGO. To this end a fibre pulling machine based on a CO2 laser as the heating element is being developed in Glasgow with funding from EGO and PPARC. At the moment a significant limitation for proposed detectors like Advanced LIGO is expected to come from the thermal noise of the mirror coatings. An investigation on mechanical losses of silica/tantala coatings was carried out by several labs involved with Advanced LIGO R&D. Doping the tantala coating layer with titania was found to reduce the coating mechanical dissipation. A review of the results is given here.

  20. Optical and transport properties of dense liquid silica

    SciTech Connect

    Qi, Tingting; Millot, Marius; Kraus, Richard G.; Hamel, Sebastien; Root, Seth

    2015-06-15

    Using density-functional-theory based molecular dynamics and the Kubo-Greenwood linear response theory, we evaluated the high-pressure equation of state and the optical and transport properties of quartz and fused silica shock-compressed to 2000 GPa. The computed Hugoniots and corresponding optical reflectivity values are in very good agreement with published data for quartz, and new data that we obtained on fused silica using magnetically launched flyer plate experiments. The rise of optical reflectivity upon shock compression appears to be primarily a temperature-driven mechanism, which is relatively insensitive to small density variation. We observed that the electrical conductivity does not display Drude-like frequency dependence, especially at lower temperatures. In addition, the Wiedemann-Franz relation between electrical and thermal conductivities was found to be invalid. It suggests that even at three-fold compression, warm dense liquid silica on the Hugoniot curve is still far away from the degenerate limit.

  1. Heterogeneous Nucleation of Dicalcium Phosphate Dihydrate on Modified Silica Surfaces.

    PubMed

    Miller, Carrie; Komunjer, Ljepša; Hlady, Vladimir

    2010-01-01

    Heterogeneous nucleation of dicalcium phosphate dihydrate, CaHPO4•2H2O (DCPD) was studied on untreated planar fused silica and on three modified silica surfaces: octadecylsilyl (OTS) modified silica, human serum albumin treated OTS silica, and UV-oxidized 3-mercaptopropyltriethoxysilyl (MTS) modified silica. The supersaturation ratio of calcium and phosphate solution with respect to DCPD was kept below ~10. The nucleated crystals were observed 24 hours and one week after initial contact between supersaturated solutions and substrate surfaces using bright field and reflectance interference contrast microscopy. No DCPD crystals nucleated on albumin-treated OTS-silica. Majority of the DCDP crystals formed on the other modified silica surfaces appeared to be morphologically similar irrespective of the nature of nucleating substrate. Reflectance interference contrast microscopy provided a proof that the majority of the crystals on these substrates do not develop an extended contact with the substrate surface. The images showed that the most extended contact planes were between the DCPD crystals and MTS modified silica surface. The crystals nucleated on OTS-treated and untreated silica surfaces showed only few or none well-developed contact planes.

  2. FUSE observations of Luminous Blue Variables

    NASA Astrophysics Data System (ADS)

    Iping, Rosina C.; Sonneborn, George; Massa, Derck L.

    P Cyg, AG Car, HD 5980 and η Car were observed with the Far Ultraviolet Spectroscopic Explorer ( FUSE) satellite. FUSE covers the spectral range from 980 Å to 1187 Å at a resolution of 0.05 Å. In this paper we discuss the far-UV properties of these LBVs and explore their similarities and differences. The FUSE observations of P Cyg and AG Car, both spectral type B2pe, are very similar. The atmospheres of both η Car and HD 5980 appear to be somewhat hotter and have much higher ionization stages (Si IV, S IV, and P V) in the FUSE spectrum than P Cyg and AG Car. There is a very good agreement between the FUSE spectrum of P Cygni and the model atmosphere computed by John Hillier with his code CMFGEN. The FUSE spectrum of η Car, however, does not agree very well with existing model spectra.

  3. Dependence of flame characteristics on the bubble generation and hydroxyl content in silica glass

    NASA Astrophysics Data System (ADS)

    Sekiya, E. H.; Torikai, D.; Suzuki, C. K.

    High quality silica glass was prepared by flame fusion Verneuil technique using two types of silica powders: purified natural quartz and synthetic sol-gel silica. Two different types of flames, GC2/O2 and LPG/O2, with various conditions of mixture ratios were used. Bubble generation and hydroxyl incorporation were analyzed in these as-fused materials. Silica glass prepared with purified natural quartz powder showed large concentration of bubbles in the most recently fused region. The bubbles were generated from the fluid and depending on the fusion condition it was possible to obtain bubble-free silica glass. A strong dependence of hydroxyl concentration on the flame mixture ratio was also observed.

  4. Internal fuse modules for solid tantalum capacitors

    NASA Technical Reports Server (NTRS)

    Dematos, H. V.

    1981-01-01

    Miniature fuse modules were designed for and incorporated into two styles of solid tantalum capacitors. One is an epoxy molded, radial leaded, high frequency decoupling capacitor; the other is an hermetically sealed device with axial lead wires. The fusible element for both devices consists of a fine bimetallic wire which reacts exothermically upon reaching a critical temperature and then disintegrates. The desirability of having fused devices is discussed and design constraints, in particular those which minimize inductance and series resistance while optimizing fuse actuation characteristics, are reviewed. Factors affecting the amount of energy required to actuate the fuse and reliability of acuation are identified.

  5. Integrated fuses for OLED lighting device

    DOEpatents

    Pschenitzka, Florian

    2007-07-10

    An embodiment of the present invention pertains to an electroluminescent lighting device for area illumination. The lighting device is fault tolerant due, in part, to the patterning of one or both of the electrodes into strips, and each of one or more of these strips has a fuse formed on it. The fuses are integrated on the substrate. By using the integrated fuses, the number of external contacts that are used is minimized. The fuse material is deposited using one of the deposition techniques that is used to deposit the thin layers of the electroluminescent lighting device.

  6. The effect of heat treatment on the magnitude and composition of residual gas in sealed silica glass ampoules

    NASA Technical Reports Server (NTRS)

    Palosz, W.; Szofran, F. R.; Lehoczky, S. L.

    1994-01-01

    The residual gas pressure and composition in sealed silica glass ampoules as a function of different treatment procedures has been investigated. The dependence of the residual gas on the outgassing and annealing parameters has been determined. The effects of the fused silica brand, of the ampoule fabrication, and of post-outgassing procedures have been evaluated.

  7. Precise Sealing of Fused-Quartz Ampoules

    NASA Technical Reports Server (NTRS)

    Debnan, W. J. J.; Clark, I. O.

    1982-01-01

    New technique rapidly evacuates and seals fused-quartz ampoule with precise clearance over contents without appreciably thinning ampoule walls. Quartz plug is lowered into working section of ampoule after ampoule has been evacuated. Plug is then fused to ampoule walls, forming vacuum seal. New technique maintains wall strength and pumping speed.

  8. Blast Off into Space Science with Fuses.

    ERIC Educational Resources Information Center

    Bombaugh, Ruth

    2000-01-01

    Introduces an activity in which students build a fuse with steel, wood, light bulbs, copper wire, clay, and batteries. Uses the cross-age instructional approach to teach about the value of instructional time. Contains directions for building a fuse. (YDS)

  9. Microgravity Manufacturing Via Fused Deposition

    NASA Technical Reports Server (NTRS)

    Cooper, K. G.; Griffin, M. R.

    2003-01-01

    Manufacturing polymer hardware during space flight is currently outside the state of the art. A process called fused deposition modeling (FDM) can make this approach a reality by producing net-shaped components of polymer materials directly from a CAE model. FDM is a rapid prototyping process developed by Stratasys, Inc.. which deposits a fine line of semi-molten polymer onto a substrate while moving via computer control to form the cross-sectional shape of the part it is building. The build platen is then lowered and the process is repeated, building a component directly layer by layer. This method enables direct net-shaped production of polymer components directly from a computer file. The layered manufacturing process allows for the manufacture of complex shapes and internal cavities otherwise impossible to machine. This task demonstrated the benefits of the FDM technique to quickly and inexpensively produce replacement components or repair broken hardware in a Space Shuttle or Space Station environment. The intent of the task was to develop and fabricate an FDM system that was lightweight, compact, and required minimum power consumption to fabricate ABS plastic hardware in microgravity. The final product of the shortened task turned out to be a ground-based breadboard device, demonstrating miniaturization capability of the system.

  10. Laser welding of fused quartz

    DOEpatents

    Piltch, Martin S.; Carpenter, Robert W.; Archer, III, McIlwaine

    2003-06-10

    Refractory materials, such as fused quartz plates and rods are welded using a heat source, such as a high power continuous wave carbon dioxide laser. The radiation is optimized through a process of varying the power, the focus, and the feed rates of the laser such that full penetration welds may be accomplished. The process of optimization varies the characteristic wavelengths of the laser until the radiation is almost completely absorbed by the refractory material, thereby leading to a very rapid heating of the material to the melting point. This optimization naturally occurs when a carbon dioxide laser is used to weld quartz. As such this method of quartz welding creates a minimum sized heat-affected zone. Furthermore, the welding apparatus and process requires a ventilation system to carry away the silicon oxides that are produced during the welding process to avoid the deposition of the silicon oxides on the surface of the quartz plates or the contamination of the welds with the silicon oxides.

  11. Single connector provides safety fuses for multiple lines

    NASA Technical Reports Server (NTRS)

    Weber, G. J.

    1966-01-01

    Fuse-bearing sleeve which is inserted between the male and female members of a multiple-line connector contains a safety fuse for each pin of the connector assembly. The sleeve is easily and quickly opened for fuse replacement.

  12. Multifunctional mesoporous silica catalyst

    DOEpatents

    Lin, Victor Shang-Yi; Tsai, Chih-Hsiang; Chen, Hung-Ting; Pruski, Marek; Kobayashi, Takeshi

    2015-03-31

    The present invention provides bifunctional silica mesoporous materials, including mesoporous silica nanoparticles ("MSN"), having pores modified with diarylammonium triflate and perfluoroaryl moieties, that are useful for the acid-catalyzed esterification of organic acids with organic alcohols.

  13. Silica extraction from geothermal water

    DOEpatents

    Bourcier, William L; Bruton, Carol J

    2014-09-23

    A method of producing silica from geothermal fluid containing low concentration of the silica of less than 275 ppm includes the steps of treating the geothermal fluid containing the silica by reverse osmosis treatment thereby producing a concentrated fluid containing the silica, seasoning the concentrated fluid thereby producing a slurry having precipitated colloids containing the silica, and separating the silica from the slurry.

  14. Femtosecond laser fabrication of nanostructures in silica glass.

    PubMed

    Taylor, R S; Hnatovsky, C; Simova, E; Rayner, D M; Bhardwaj, V R; Corkum, P B

    2003-06-15

    A femtosecond laser beam focused inside fused silica and other glasses can modify the refractive index of the glass. Chemical etching and atomic-force microscope studies show that the modified region can have a sharp-tipped cone-shaped structure with a tip diameter as small as 100 nm. Placing the structure near the bottom surface of a silica glass sample and applying a selective chemical etch to the bottom surface produces clean, circular, submicrometer-diameter holes. Holes spaced as close to one another as 1.4 microm are demonstrated.

  15. Organometallic chemistry: Fused ferrocenes come full circle

    NASA Astrophysics Data System (ADS)

    Musgrave, Rebecca A.; Manners, Ian

    2016-09-01

    Chemists have long been fascinated by electron delocalization, from both a fundamental and applied perspective. Macrocyclic oligomers containing fused ferrocenes provide a new structural framework -- containing strongly interacting metal centres -- that is capable of supporting substantial charge delocalization.

  16. Coordination chemistry in fused-salt solutions

    NASA Technical Reports Server (NTRS)

    Gruen, D. M.

    1969-01-01

    Spectrophotometric work on structural determinations with fused-salt solutions is reviewed. Constraints placed on the method, as well as interpretation of the spectra, are discussed with parallels drawn to aqueous spectrophotometric curves of the same materials.

  17. Process for energy reduction with flash fusing

    SciTech Connect

    Berkes, J.S.

    1987-10-06

    This patent describes a process for affecting a reduction in the energy needed for accomplishing the flash fusing of a developed image which comprises (1) providing a toner composition with resin particles, pigment articles, and wax. The wax possesses a lower melting temperature than the resin particles and is selected from the group consisting of polyethylene and polypropylene with a molecular weight of less than about 6,000; (2) introducing the aforementioned toner composition into a xerographic imaging apparatus having incorporated therein a flash fusing device; (3) generating an electrostatic latent image in the imaging apparatus, and subsequently developing this image with the toner composition; (4) transferring the image to a supporting substrate; and (5) permanently attaching the image to the substrate with energy emitted from a flash fusing device, and wherein there is formed between the supporting substrate and the toner composition during fusing a wax layer.

  18. Processing pathway dependence of amorphous silica nanoparticle toxicity - colloidal versus pyrolytic

    PubMed Central

    Zhang, Haiyuan; Dunphy, Darren R.; Jiang, Xingmao; Meng, Huan; Sun, Bingbing; Tarn, Derrick; Xue, Min; Wang, Xiang; Lin, Sijie; Ji, Zhaoxia; Li, Ruibin; Garcia, Fred L.; Yang, Jing; Kirk, Martin L.; Xia, Tian; Zink, Jeffrey I; Nel, Andre; Brinker, C. Jeffrey

    2012-01-01

    We have developed structure/toxicity relationships for amorphous silica nanoparticles (NPs) synthesized through low temperature, colloidal (e.g. Stöber silica) or high temperature pyrolysis (e.g. fumed silica) routes. Through combined spectroscopic and physical analyses, we have determined the state of aggregation, hydroxyl concentration, relative proportion of strained and unstrained siloxane rings, and potential to generate hydroxyl radicals for Stöber and fumed silica NPs with comparable primary particle sizes (16-nm in diameter). Based on erythrocyte hemolytic assays and assessment of the viability and ATP levels in epithelial and macrophage cells, we discovered for fumed silica an important toxicity relationship to post-synthesis thermal annealing or environmental exposure, whereas colloidal silicas were essentially non-toxic under identical treatment conditions. Specifically, we find for fumed silica a positive correlation of toxicity with hydroxyl concentration and its potential to generate reactive oxygen species (ROS) and cause red blood cell hemolysis. We propose fumed silica toxicity stems from its intrinsic population of strained three-membered rings (3MRs) along with its chain-like aggregation and hydroxyl content. Hydrogen-bonding and electrostatic interactions of the silanol surfaces of fumed silica aggregates with the extracellular plasma membrane cause membrane perturbations sensed by the Nalp3 inflammasome, whose subsequent activation leads to secretion of the cytokine IL-1β. Hydroxyl radicals generated by the strained 3MRs in fumed silica but largely absent in colloidal silicas may contribute to the inflammasome activation. Formation of colloidal silica into aggregates mimicking those of fumed silica had no effect on cell viability or hemolysis. This study emphasizes that not all amorphous silica is created equal and that the unusual toxicity of fumed silica compared to colloidal silica derives from its framework and surface chemistry along

  19. Fabrication of microhole arrays on coated silica sheet using femtosecond laser

    NASA Astrophysics Data System (ADS)

    Wang, Zhuping; Feng, Guoying; Han, Jinghua; Wang, Shutong; Hu, Ruifeng; Li, Guang; Dai, Shenyu; Zhou, Shouhuan

    2016-10-01

    A femtosecond (fs) laser beam machining method has been proposed to improve the quality of micromachining. At first, the coated silica sheet is prepared by pulsed laser deposition, then the coated silica is processed by the fs laser. After that, the aluminum film on a fused silica sheet is cleared out by hydrochloric acid (HCl) in a solution of 10%, and then the microhole array is formed on the silica which has better morphologies. Additionally, some mathematical models are constructed to analyze the diffusion of vapors and reflection of shock waves during the machining process. The theoretical results show that the aluminum film can effectively decrease the pressure gradient of the vapors and the reflection of shock wave pressure on the fused silica during the machining process. The simulation is consistent with experimental results. Finally, coating with a film or not has a great influence on the quality of micromachining, but the types of coating films have little influence. In a word, it is an excellent choice to improve the quality of fs laser processing by coating with a film on a fused silica sheet.

  20. Fused Bead Analysis of Diogenite Meteorites

    NASA Technical Reports Server (NTRS)

    Mittlefehldt, D.W.; Beck, B.W.; McSween, H.Y.; Lee, C.T. A.

    2009-01-01

    Bulk rock chemistry is an essential dataset in meteoritics and planetary science [1]. A common method used to obtain the bulk chemistry of meteorites is ICP-MS. While the accuracy, precision and low detection limits of this process are advantageous [2], the sample size used for analysis (approx.70 mg) can be a problem in a field where small and finite samples are the norm. Fused bead analysis is another bulk rock analytical technique that has been used in meteoritics [3]. This technique involves forming a glass bead from 10 mg of sample and measuring its chemistry using a defocused beam on a microprobe. Though the ICP-MS has lower detection limits than the microprobe, the fused bead method destroys a much smaller sample of the meteorite. Fused bead analysis was initially designed for samples with near-eutectic compositions and low viscosities. Melts generated of this type homogenize at relatively low temperatures and produce primary melts near the sample s bulk composition [3]. The application of fused bead analysis to samples with noneutectic melt compositions has not been validated. The purpose of this study is to test if fused bead analysis can accurately determine the bulk rock chemistry of non-eutectic melt composition meteorites. To determine this, we conduct two examinations of the fused bead. First, we compare ICP-MS and fused bead results of the same samples using statistical analysis. Secondly, we inspect the beads for the presence of crystals and chemical heterogeneity. The presence of either of these would indicate incomplete melting and quenching of the bead.

  1. Quantitative evaluation of fiber fuse initiation with exposure to arc discharge provided by a fusion splicer

    NASA Astrophysics Data System (ADS)

    Todoroki, Shin-Ichi

    2016-05-01

    The optical communication industry and power-over-fiber applications face a dilemma as a result of the expanding demand of light power delivery and the potential risks of high-power light manipulation including the fiber fuse phenomenon, a continuous destruction of the fiber core pumped by the propagating light and triggered by a heat-induced strong absorption of silica glass. However, we have limited knowledge on its initiation process in the viewpoint of energy flow in the reactive area. Therefore, the conditions required for a fiber fuse initiation in standard single-mode fibers were determined quantitatively, namely the power of a 1480 nm fiber laser and the arc discharge intensity provided by a fusion splicer for one second as an outer heat source. Systematic investigation on the energy flow balance between these energy sources revealed that the initiation process consists of two steps; the generation of a precursor at the heated spot and the transition to a stable fiber fuse. The latter step needs a certain degree of heat accumulation at the core where waveguide deformation is ongoing competitively. This method is useful for comparing the tolerance to fiber fuse initiation among various fibers with a fixed energy amount that was not noticed before.

  2. Spherical ordered mesoporous silicas and silica monoliths as stationary phases for liquid chromatography.

    PubMed

    Galarneau, Anne; Iapichella, Julien; Brunel, Daniel; Fajula, François; Bayram-Hahn, Zöfre; Unger, Klaus; Puy, Guillaume; Demesmay, Claire; Rocca, Jean-Louis

    2006-04-01

    cladding problems to evaluate the resulting macromonoliths in HPLC, micromonoliths were synthesized into fused-silica capillaries and evaluated by nano-LC and CEC. Only CEC allows to gain high column efficiencies in fast separation processes. Capillary silica monolithic columns represent attractive alternatives for miniaturization processes (lab-on-a chip) using CEC.

  3. Wafer-fused semiconductor radiation detector

    DOEpatents

    Lee, Edwin Y.; James, Ralph B.

    2002-01-01

    Wafer-fused semiconductor radiation detector useful for gamma-ray and x-ray spectrometers and imaging systems. The detector is fabricated using wafer fusion to insert an electrically conductive grid, typically comprising a metal, between two solid semiconductor pieces, one having a cathode (negative electrode) and the other having an anode (positive electrode). The wafer fused semiconductor radiation detector functions like the commonly used Frisch grid radiation detector, in which an electrically conductive grid is inserted in high vacuum between the cathode and the anode. The wafer-fused semiconductor radiation detector can be fabricated using the same or two different semiconductor materials of different sizes and of the same or different thicknesses; and it may utilize a wide range of metals, or other electrically conducting materials, to form the grid, to optimize the detector performance, without being constrained by structural dissimilarity of the individual parts. The wafer-fused detector is basically formed, for example, by etching spaced grooves across one end of one of two pieces of semiconductor materials, partially filling the grooves with a selected electrical conductor which forms a grid electrode, and then fusing the grooved end of the one semiconductor piece to an end of the other semiconductor piece with a cathode and an anode being formed on opposite ends of the semiconductor pieces.

  4. OPUS: the FUSE science data pipeline

    NASA Astrophysics Data System (ADS)

    Rose, James F.; Heller-Boyer, C.; Rose, M. A.; Swam, M.; Miller, W.; Kriss, G. A.; Oegerle, William R.

    1998-07-01

    This paper describes how the OPUS pipeline, currently used for processing science data from the Hubble Space Telescope (HST), was used as the backbone for developing the science data pipeline for a much smaller mission. The far ultraviolet spectroscopic explorer (FUSE) project selected OPUS for its data processing pipeline platform and selected the OPUS team at the STScI to write the FUSE pipeline applications. A total of 105 new modules were developed for the FUSE pipeline. The foundation of over 250 modules in the OPUS libraries allowed development to proceed quickly and with considerable confidence that the underlying functionality is reliable and robust. Each task represented roughly 90 percent reuse, and the project as a whole shows over 70 percent reuse of the existing OPUS system. Taking an existing system that is operational, and will be maintained for many years to come, was a key decision for the FUSE mission. Adding the extensive experience of the OPUS team to the task resulted in the development of a complete telemetry pipeline system within a matter of months. Reusable software has been the siren song of software engineering and object- oriented design for a decade or more. The development of inexpensive software systems by adapting existing code to new applications is as attractive as it has been elusive. The OPUS telemetry pipeline for the FUSE mission has proven to be a significant exception to that trend.

  5. Silica-Ceria Hybrid Nanostructures

    SciTech Connect

    Munusamy, Prabhakaran; Sanghavi, Shail P.; Nachimuthu, Ponnusamy; Baer, Donald R.; Thevuthasan, Suntharampillai

    2012-04-25

    A new hybrid material system that consists of ceria attached silica nanoparticles has been developed. Because of the versatile properties of silica and versatile properties of silica and versatile properties of silica and versatile properties of silica and versatile properties of silica and versatile properties of silica and versatile properties of silica and versatile properties of silica and versatile properties of silica and versatile properties of silica and versatile properties of silica and versatile properties of silica and antioxidant properties of ceria nanoparticles, this material system is ideally suited for biomedical applications. The silica particles of size ~50nm were synthesized by the Stöber synthesis method and ceria nanoparticles of size ~2-3nm was attached to the silica surface using a hetrocoagulation method. The presence of silanol groups on the surface of silica particles mediated homogenous nucleation of ceria which were attached to silica surface by Si-O-Ce bonding. The formations of silica-ceria hybrid nanostructures were characterized by X-photoelectron spectroscopy (XPS) and high resolution transmission electron microscopy (HRTEM). The HRTEM image confirms the formation of individual crystallites of ceria nanoparticles attached to the silica surface. The XPS analysis indicates that ceria nanoparticles are chemically bonded to surface of silica and possess mixture of +3 and +4 chemical states.

  6. Propagation mechanism of polymer optical fiber fuse

    PubMed Central

    Mizuno, Yosuke; Hayashi, Neisei; Tanaka, Hiroki; Nakamura, Kentaro; Todoroki, Shin-ichi

    2014-01-01

    A fiber fuse phenomenon in polymer optical fibers (POFs) has recently been observed, and its unique properties such as slow propagation, low threshold power density, and the formation of a black oscillatory damage curve, have been reported. However, its characterization is still insufficient to well understand the mechanism and to avoid the destruction of POFs. Here, we present detailed experimental and theoretical analyses of the POF fuse propagation. First, we clarify that the bright spot is not a plasma but an optical discharge, the temperature of which is ~3600 K. We then elucidate the reasons for the oscillation of the damage curve along with the formation of newly-observed gas bubbles as well as for the low threshold power density. We also present the idea that the POF fuse can potentially be exploited to offer a long photoelectric interaction length. PMID:24762949

  7. High-purity silica reflecting heat shield development

    NASA Technical Reports Server (NTRS)

    Congdon, W. M.

    1974-01-01

    A high-purity, fused-silica reflecting heat shield for the thermal protection of outer-planet probes was developed. Factors that strongly influence the performance of a silica heat shield were studied. Silica-bonded silica configurations, each prepared by a different technique, were investigated and rated according to its relative merits. Slip-casting was selected as the preferred fabrication method because it produced good reflectivity and good strength, and is relatively easy to scale up for a full-size outer-planet probe. The slips were cast using a variety of different particle sizes: continuous particle-size slips; monodisperse particle-size slips; and blends of monodisperse particle-size slips were studied. In general, smaller particles gave the highest reflectance. The monodisperse slips as well as the blend slips gave a higher reflectance than the continuous particle-size slips. An upgraded and fused natural quartz was used to study the effects of microstructure on reflectance and as the baseline to ascertain the increase in reflectance obtained from using a higher-purity synthetic material.

  8. 200 kj copper foil fuses. Final report

    SciTech Connect

    McClenahan, C.R.; Goforth, J.H.; Degnan, J.H.; Henderson, R.M.; Janssen, W.H.

    1980-04-01

    A 200-kJ, 50-kV capacitor bank has been discharged into 1-mil-thick copper foils immersed in fine glass beads. These foils ranged in length from 27 to 71 cm and in width from 15 to 40 cm. Voltage spikes of over 250 kV were produced by the resulting fuse behavior of the foil. Moreover, the current turned off at a rate that was over 6 times the initial bank dI/dt. Full widths at half maxima for the voltage and dI/dt spikes were about 0.5 microsec, with some as short as 300 nanosec. Electrical breakdown was prevented in all but one size fuze with maximum applied fields of 7 kV/cm. Fuses that were split into two parallel sections have been tested, and the effects relative to one-piece fuses are much larger than would be expected on the basis of inductance differences alone. A resistivity model for copper foil fuses, which differs from previous work in that it includes a current density dependence, has been devised. Fuse behavior is predicted with reasonable accuracy over a wide range of foil sizes by a quasi-two-dimensional fuse code that incorporates this resistivity model. A variation of Maisonnier's method for predicting optimum fuze size has been derived. This method is valid if the risetime of the bank exceeds 3 microsec, in which case it can be expected to be applicable over a wide range of peak current densities.

  9. Silazine to silica

    NASA Technical Reports Server (NTRS)

    Harvey, Gale A.

    1993-01-01

    Thin film silica and/or methyl silicone were detected on most external surfaces of the retrieved LDEF. Both solar ultraviolet radiation and atomic oxygen can convert silicones to silica. Known sources of silicone in or on the LDEF appear inadequate to explain the ubiquitous presence of the silica and silicone films. Hexamethyldisilazane (HMDS) was used as the Challenger tile waterproofing compound for the Challenger/LDEF deployment mission. HMDS is both volatile and chemically reactive at STP. In addition, HMDS releases NH3 which depolymerizes silicone RTV's. Polyurethanes are also depolymerized. Experiments are reported that indicate much of the silicone and silica contamination of LDEF resulted directly or indirectly from HMDS.

  10. Silica-alumina trihydrate filled epoxy castings resistant to arced SF.sub.6

    DOEpatents

    Chenoweth, Terrence E.; Yeoman, Frederick A.

    1978-01-01

    A cured, insulating, casting composition, having a coefficient of linear thermal expansion of below about 38 .times. 10.sup.-6 in./in./.degree. C and being resistant to arced sulfur hexafluoride gas, in contact with a metal surface in a sulfur hexafluoride gas environment, is made from hydantoin epoxy resin, anhydride curing agent and a filler combination of fused silica and alumina trihydrate.

  11. Helicopter Aircrew Training Using Fused Reality

    DTIC Science & Technology

    2006-06-01

    RTO-MP-HFM-136 27 - 1 Helicopter Aircrew Training Using Fused Reality Dr. Ed Bachelder Systems Technology Inc. 13766 Hawthorne Blvd...applied to training helicopter aircrew personnel using a prototype simulator, the Prototype Aircrew Virtual Environment Training (PAVET) System...cabin) pixels using blue screen imaging techniques. This bitmap is overlaid on a virtual environment, and sent Bachelder, E. (2006) Helicopter Aircrew

  12. Crystal growth in fused solvent systems

    NASA Technical Reports Server (NTRS)

    Ulrich, D. R.; Noone, M. J.; Spear, K. E.; White, W. B.; Henry, E. C.

    1973-01-01

    Research is reported on the growth of electronic ceramic single crystals from solution for the future growth of crystals in a microgravity environment. Work included growth from fused or glass solvents and aqueous solutions. Topics discussed include: crystal identification and selection; aqueous solution growth of triglycine sulphate (TGS); and characterization of TGS.

  13. Fused thiophene derivatives as MEK inhibitors.

    PubMed

    Laing, Victoria E; Brookings, Daniel C; Carbery, Rachel J; Simorte, Jose Gascon; Hutchings, Martin C; Langham, Barry J; Lowe, Martin A; Allen, Rodger A; Fetterman, Joanne R; Turner, James; Meier, Christoph; Kennedy, Jeff; Merriman, Mark

    2012-01-01

    A number of novel fused thiophene derivatives have been prepared and identified as potent inhibitors of MEK. The SAR data of selected examples and the in vivo profiling of compound 13 h demonstrates the functional activity of this class of compounds in HT-29 PK/PD models.

  14. Silica, Silicosis, and Autoimmunity

    PubMed Central

    Pollard, Kenneth Michael

    2016-01-01

    Inhalation of dust containing crystalline silica is associated with a number of acute and chronic diseases including systemic autoimmune diseases. Evidence for the link with autoimmune disease comes from epidemiological studies linking occupational exposure to crystalline silica dust with the systemic autoimmune diseases systemic lupus erythematosus, systemic sclerosis, and rheumatoid arthritis. Although little is known regarding the mechanism by which silica exposure leads to systemic autoimmune disease, there is a voluminous literature on silica exposure and silicosis that may help identify immune processes that precede development of autoimmunity. The pathophysiology of silicosis consists of deposition of silica particles in the alveoli of the lung. Ingestion of these particles by macrophages initiates an inflammatory response, which stimulates fibroblasts to proliferate and produce collagen. Silica particles are encased by collagen leading to fibrosis and the nodular lesions characteristic of the disease. The steps in the development of silicosis, including acute and chronic inflammation and fibrosis, have different molecular and cellular requirements, suggesting that silica-induced inflammation and fibrosis may be mechanistically separate. Significantly, it is unclear whether silica-induced inflammation and fibrosis contribute similarly to the development of autoimmunity. Nonetheless, the findings from human and animal model studies are consistent with an autoimmune pathogenesis that begins with activation of the innate immune system leading to proinflammatory cytokine production, pulmonary inflammation leading to activation of adaptive immunity, breaking of tolerance, and autoantibodies and tissue damage. The variable frequency of these immunological features following silica exposure suggests substantial genetic involvement and gene/environment interaction in silica-induced autoimmunity. However, numerous questions remain unanswered. PMID:27014276

  15. Application of silica nanoparticles for increased silica availability in maize

    NASA Astrophysics Data System (ADS)

    Suriyaprabha, R.; Karunakaran, G.; Yuvakkumar, R.; Prabu, P.; Rajendran, V.; Kannan, N.

    2013-02-01

    Silica nanoparticles were extracted from rice husk and characterised comprehensively. The synthesised silica powders were amorphous in size with 99.7% purity (20-40 nm). Nanosilica was amended with red soil at 15 kg ha-1 along with micron silica. The influence of nanoscale on silica uptake, accumulation and nutritional variations in maize roots were evaluated through the studies such as root sectioning, elemental analysis and physiological parameters (root length and silica content) and compared with micron silica and control. Nanosilica treated soil reveals enhanced silica uptake and elongated roots which make the plant to resist in stress conditions like drought.

  16. Cam-operated limit switch features safe fuse replacement

    NASA Technical Reports Server (NTRS)

    Weber, G. J.

    1965-01-01

    Two hermetically sealed, short travel, limit switches permit fuse replacement without danger of a spark or arcing. The switches are wired in parallel circuits and actuated by manually operated cams containing the circuit fuses.

  17. 29 CFR 1926.907 - Use of safety fuse.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... way shall be forbidden. (b) The hanging of a fuse on nails or other projections which will cause a... destroyed. (f) No fuse shall be capped, or primers made up, in any magazine or near any possible source...

  18. 29 CFR 1926.907 - Use of safety fuse.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... way shall be forbidden. (b) The hanging of a fuse on nails or other projections which will cause a... destroyed. (f) No fuse shall be capped, or primers made up, in any magazine or near any possible source...

  19. Multimodal plasmonics in fused colloidal networks

    NASA Astrophysics Data System (ADS)

    Teulle, Alexandre; Bosman, Michel; Girard, Christian; Gurunatha, Kargal L.; Li, Mei; Mann, Stephen; Dujardin, Erik

    2015-01-01

    Harnessing the optical properties of noble metals down to the nanometre scale is a key step towards fast and low-dissipative information processing. At the 10-nm length scale, metal crystallinity and patterning as well as probing of surface plasmon properties must be controlled with a challenging high level of precision. Here, we demonstrate that ultimate lateral confinement and delocalization of surface plasmon modes are simultaneously achieved in extended self-assembled networks comprising linear chains of partially fused gold nanoparticles. The spectral and spatial distributions of the surface plasmon modes associated with the colloidal superstructures are evidenced by performing monochromated electron energy-loss spectroscopy with a nanometre-sized electron probe. We prepare the metallic bead strings by electron-beam-induced interparticle fusion of nanoparticle networks. The fused superstructures retain the native morphology and crystallinity but develop very low-energy surface plasmon modes that are capable of supporting long-range and spectrally tunable propagation in nanoscale waveguides.

  20. Fast Color Change with Photochromic Fused Naphthopyrans.

    PubMed

    Sousa, Céu M; Berthet, Jerome; Delbaere, Stephanie; Polónia, André; Coelho, Paulo J

    2015-12-18

    Photochromic molecules can reversibly develop color upon irradiation with UV light. These smart molecules, mainly in the naphthopyran family, have been applied with success to ophthalmic lenses that darken quickly under sunlight and revert to the uncolored state after several minutes in the dark. This slow adaptation to the absence of light is one of the limitations and is due to the formation of an unwanted photoisomer. We have designed a new naphthopyran with a bridged structure which prohibits the formation of the undesirable, persistent photoisomer and thus shows a very fast switching between the uncolored and colored states. UV irradiation of a hybrid siloxane matrix doped with the new fused naphthopyran leads to the formation of a pink coloration bleaching in a few milliseconds, in the absence of light, at room temperature. This new fused naphthopyran is easily prepared in three steps from readily accessible precursors and is amenable to structural modifications to tailor color and lifetime of the colored photoisomer.

  1. Periclase-chromite refractories from fused materials

    SciTech Connect

    Slovikovskii, V.V.; Eroshkina, V.I.; Kononenko, G.V.; Nechistykh, G.A.; Simonov, K.V.

    1985-11-01

    Experiments were carried out to obtain high-grade fused chromitepericlase. It is shown that during the melting of batch consisting of raw magnesite and chromite ore the process of reducing the chromite ore to metallic ferrochromium is eliminated, which adversely affects both the content of Cr/sub 2/O/sub 3/ in the fused material, and also the commercial appearance of the resulting refractories. The authors developed a technology for preparing periclase-chromite refractories with chrommite-periclase constituents. The goods obtained possess good physicoceramic properties and a low content of silicites. The articles thus prepared were used to make the linings of the most critical parts of the converters which allowed an increase to be made in the duration of campaigns for the Kivset units of 1.5-2 times.

  2. Multimodal Plasmonics in Fused Colloidal Networks

    PubMed Central

    Teulle, Alexandre; Bosman, Michel; Girard, Christian; Gurunatha, Kargal L.; Li, Mei; Mann, Stephen; Dujardin, Erik

    2014-01-01

    Harnessing the optical properties of noble metals down to the nanometer-scale is a key step towards fast and low-dissipative information processing. At the 10-nm length scale, metal crystallinity and patterning as well as probing of surface plasmon (SP) properties must be controlled with a challenging high level of precision. Here, we demonstrate that ultimate lateral confinement and delocalization of SP modes are simultaneously achieved in extended self-assembled networks comprising linear chains of partially fused gold nanoparticles. The spectral and spatial distributions of the SP modes associated with the colloidal superstructures are evidenced by performing monochromated electron energy loss spectroscopy with a nanometer-sized electron probe. We prepare the metallic bead strings by electron beam-induced interparticle fusion of nanoparticle networks. The fused superstructures retain the native morphology and crystallinity but develop very low energy SP modes that are capable of supporting long range and spectrally tunable propagation in nanoscale waveguides. PMID:25344783

  3. Demonstrating Earth connections and fuses working together

    NASA Astrophysics Data System (ADS)

    Harrison, Mark

    2017-03-01

    Earth wires and fuses work together in UK mains circuits to keep users safe from electric shocks and are taught in many school contexts. The subject can be quite abstract and difficult for pupils to grasp, and a simple but visually clear and direct demonstration is described which would be easy for most physics departments to build and which can make the concepts much more immediately understandable.

  4. Thermal fuse for high-temperature batteries

    DOEpatents

    Jungst, Rudolph G.; Armijo, James R.; Frear, Darrel R.

    2000-01-01

    A thermal fuse, preferably for a high-temperature battery, comprising leads and a body therebetween having a melting point between approximately 400.degree. C. and 500.degree. C. The body is preferably an alloy of Ag--Mg, Ag--Sb, Al--Ge, Au--In, Bi--Te, Cd--Sb, Cu--Mg, In--Sb, Mg--Pb, Pb--Pd, Sb--Zn, Sn--Te, or Mg--Al.

  5. 49 CFR 173.184 - Highway or rail fusee.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... SHIPMENTS AND PACKAGINGS Non-bulk Packaging for Hazardous Materials Other Than Class 1 and Class 7 § 173.184 Highway or rail fusee. (a) A fusee is a device designed to burn at a controlled rate and to produce visual...), plywood (1D) or fiber (1G) drums. If the fusees are equipped with spikes packagings must have...

  6. Implantation-induced structural and surface modification of silica

    NASA Astrophysics Data System (ADS)

    Johnson, C. M.; Thompson, T. D.; Ridgway, M. C.; Gurarie, V.

    1998-05-01

    Ion irradiation of silica causes compaction of the substrate over the extent of the ion range and the resulting increase in refractive index has applications to optical waveguide fabrication. Several analytical techniques have been utilized to characterize implantation-induced structural and surface modifications of silica with the aim of yielding further insight into this technologically relevant process. Substrates of both fused silica and plasma-enhanced chemical vapor deposited silica-on-Si were implanted with C, Si or Ge ions at an energy of 5 MeV and a temperature of -196°C over a range of ion fluences. Compaction of the substrate was characterized as a function of ion dose with both standard profilometry and extended X-ray absorption fine structure (EXAFS). With the former, the extent of compaction was dependent on the silica density with a saturation of the compaction for all substrates at an ion fluence of ˜10 15/cm 2. With EXAFS, complementary information on implantation-induced effects at the atomic scale were determined to differentiate the influences of bond length and bond angle changes in the compaction process. No changes in nearest-neighbour bond length were observed following compaction. The condition of the substrate surface during ion implantation was recorded by in situ photography. Cracking of the surface, as a means of stress relief, was observed and thereafter, the evolution of the cracked surface was quantitatively characterized as a function of ion fluence.

  7. Electrochemical Sensors: Functionalized Silica

    SciTech Connect

    Fryxell, Glen E.; Lin, Yuehe; Yantasee, Wassana

    2009-03-24

    This chapter summarizes recent devellopment of electrochemical sensors based on functionlized mesoporous silica materials. The nanomatrials based sensors have been developed for sensitive and selective enrironmental detection of toxic heavy metal and uranium ions.

  8. Cellulose-silica aerogels.

    PubMed

    Demilecamps, Arnaud; Beauger, Christian; Hildenbrand, Claudia; Rigacci, Arnaud; Budtova, Tatiana

    2015-05-20

    Aerogels based on interpenetrated cellulose-silica networks were prepared and characterised. Wet coagulated cellulose was impregnated with silica phase, polyethoxydisiloxane, using two methods: (i) molecular diffusion and (ii) forced flow induced by pressure difference. The latter allowed an enormous decrease in the impregnation times, by almost three orders of magnitude, for a sample with the same geometry. In both cases, nanostructured silica gel was in situ formed inside cellulose matrix. Nitrogen adsorption analysis revealed an almost threefold increase in pores specific surface area, from cellulose aerogel alone to organic-inorganic composite. Morphology, thermal conductivity and mechanical properties under uniaxial compression were investigated. Thermal conductivity of composite aerogels was lower than that of cellulose aerogel due to the formation of superinsulating mesoporous silica inside cellulose pores. Furthermore, composite aerogels were stiffer than each of reference aerogels.

  9. Crystalline Silica Primer

    USGS Publications Warehouse

    ,

    1992-01-01

    substance and will present a nontechnical overview of the techniques used to measure crystalline silica. Because this primer is meant to be a starting point for anyone interested in learning more about crystalline silica, a list of selected readings and other resources is included. The detailed glossary, which defines many terms that are beyond the scope of this publication, is designed to help the reader move from this presentation to a more technical one, the inevitable next step.

  10. Outbursts In Symbiotic Binaries (FUSE 2000)

    NASA Technical Reports Server (NTRS)

    Kenyon, Scott J.; Sonneborn, George (Technical Monitor)

    2002-01-01

    During the past year, we made good progress on analysis of FUSE observations of the symbiotic binary Z And. For background, Z And is a binary system composed of a red giant and a hot component of unknown status. The orbital period is roughly 750 days. The hot component undergoes large-scale eruptions every 10-20 yr. An outburst began several years ago, triggering this FUSE opportunity. First, we obtained an excellent set of ground-based optical data in support, of the FUSE observations. We used FAST, a high throughput low resolution spectrograph on the 1.5-m telescope at Mt. Hopkins, Arizona. A 300 g/ mm grating blazed at 4750 A, a 3 in. slit, and a thinned Loral 512 x 2688 CCD gave us spectra covering 3800-7500 A at a resolution of 6 A. The wavelength solution for each spectrum has a probable error of +/- 0.5 A or better. Most of the resulting spectra have moderate signal-to-noise, S/.N approx. greater than 30 per pixel. The time coverage for these spectra is excellent. Typically, we acquired spectra every 1-2 nights during dark runs at Mt. Hopkins. These data cover most of the rise and all of the decline of the recent outburst. The spectra show a wealth of emission lines, including H I, He I, He II, [Fe V11], and the Raman scattering bands at 6830 A and 7088 A. The Raman bands and other high ionization features vary considerably throughout the outburst. These features will enable us to correlate variations in the FUSE spectra with variations in the optical spectra. Second, we began an analysis of FUSE spectra of Z And. We have carefully examined the spectra, identifying real features and defects. We have identified and measured fluxes for all strong emission lines, including the O VI doublet at 1032 A and 1038 A. These and several other strong emission lines display pronounced P Cygni absorption components indicative of outgrowing gas. We will attempt to correlate these velocities with similar profiles observed on optical spectra. The line velocities - together

  11. Silica, hybrid silica, hydride silica and non-silica stationary phases for liquid chromatography.

    PubMed

    Borges, Endler M

    2015-04-01

    Free silanols on the surface of silica are the "villains", which are responsible for detrimental interactions of those compounds and the stationary phase (i.e., bad peak shape, low efficiency) as well as low thermal and chemical stability. For these reasons, we began this review describing new silica and hybrid silica stationary phases, which have reduced and/or shielded silanols. At present, in liquid chromatography for the majority of analyses, reversed-phase liquid chromatography is the separation mode of choice. However, the needs for increased selectivity and increased retention of hydrophilic bases have substantially increased the interest in hydrophilic interaction chromatography (HILIC). Therefore, stationary phases and this mode of separation are discussed. Then, non-silica stationary phases (i.e., zirconium oxide, titanium oxide, alumina and porous graphitized carbon), which afford increased thermal and chemical stability and also selectivity different from those obtained with silica and hybrid silica, are discussed. In addition, the use of these materials in HILIC is also reviewed.

  12. Optical Performance Modeling of FUSE Telescope Mirror

    NASA Technical Reports Server (NTRS)

    Saha, Timo T.; Ohl, Raymond G.; Friedman, Scott D.; Moos, H. Warren

    2000-01-01

    We describe the Metrology Data Processor (METDAT), the Optical Surface Analysis Code (OSAC), and their application to the image evaluation of the Far Ultraviolet Spectroscopic Explorer (FUSE) mirrors. The FUSE instrument - designed and developed by the Johns Hopkins University and launched in June 1999 is an astrophysics satellite which provides high resolution spectra (lambda/Delta(lambda) = 20,000 - 25,000) in the wavelength region from 90.5 to 118.7 nm The FUSE instrument is comprised of four co-aligned, normal incidence, off-axis parabolic mirrors, four Rowland circle spectrograph channels with holographic gratings, and delay line microchannel plate detectors. The OSAC code provides a comprehensive analysis of optical system performance, including the effects of optical surface misalignments, low spatial frequency deformations described by discrete polynomial terms, mid- and high-spatial frequency deformations (surface roughness), and diffraction due to the finite size of the aperture. Both normal incidence (traditionally infrared, visible, and near ultraviolet mirror systems) and grazing incidence (x-ray mirror systems) systems can be analyzed. The code also properly accounts for reflectance losses on the mirror surfaces. Low frequency surface errors are described in OSAC by using Zernike polynomials for normal incidence mirrors and Legendre-Fourier polynomials for grazing incidence mirrors. The scatter analysis of the mirror is based on scalar scatter theory. The program accepts simple autocovariance (ACV) function models or power spectral density (PSD) models derived from mirror surface metrology data as input to the scatter calculation. The end product of the program is a user-defined pixel array containing the system Point Spread Function (PSF). The METDAT routine is used in conjunction with the OSAC program. This code reads in laboratory metrology data in a normalized format. The code then fits the data using Zernike polynomials for normal incidence

  13. Synthesis of novel fused quinazolinone derivatives.

    PubMed

    Mahdavi, Mohammad; Lotfi, Vahid; Saeedi, Mina; Kianmehr, Ebrahim; Shafiee, Abbas

    2016-08-01

    A four-step synthetic route was developed for the synthesis of novel fused quinazolinones, quinazolino[3,4-a]quinazolinones, and isoinodolo[2,1-a]quinazolino[1,2-c]quinazolineones. Reaction of isatoic anhydride and different amines gave various 2-aminobenzamides. Then, reaction of 2-aminobenzamides with 2-nitrobenzaldehyde followed by the reduction of nitro group afforded 2-(2-aminophenyl)-3-aryl-2,3-dihydroquinazolin-4(1H)-one derivatives. Finally, reaction of the latter compounds with aromatic aldehydes or 2-formylbenzoic acid led to the formation of the corresponding products.

  14. Evolutionary explosions and the phylogenetic fuse.

    PubMed

    Cooper, A; Fortey, R

    1998-04-01

    A literal reading of the fossil record indicates that the early Cambrian (c. 545 million years ago) and early Tertiary (c. 65 million years ago) were characterized by enormously accelerated periods of morphological evolution marking the appearance of the animal phyla, and modern bird and placental mammal orders, respectively. Recently, the evidence for these evolutionary `explosions' has been questioned by cladistic and biogeographic studies which reveal that periods of diversification before these events are missing from the fossil record. Furthermore, molecular evidence indicates that prolonged periods of evolutionary innovation and cladogenesis lit the fuse long before the `explosions' apparent in the fossil record.

  15. Medicinal Chemistry Perspective of Fused Isoxazole Derivatives.

    PubMed

    Barmade, Mahesh A; Murumkar, Prashant R; Sharma, Mayank Kumar; Yadav, Mange Ram

    2016-01-01

    Nitrogen containing heterocyclic rings with an oxygen atom is considered as one of the best combination in medicinal chemistry due to their diversified biological activities. Isoxazole, a five membered heterocyclic azole ring is found in naturally occuring ibetonic acid along with some of the marketed drugs such as valdecoxib, flucloxacillin, cloxacillin, dicloxacillin, and danazol. It is also significant for showing antipsychotic activity in risperidone and anticonvulsant activity in zonisamide, the marketed drugs. This review article covers research articles reported till date covering biological activity along with SAR of fused isoxazole derivatives.

  16. Diaphragm-free fiber-optic Fabry-Perot interferometer based on tapered hollow silica tube

    NASA Astrophysics Data System (ADS)

    Fang, Guocheng; Jia, Pinggang; Liang, Ting; Tan, Qiulin; Hong, Yingping; Liu, Wenyi; Xiong, Jijun

    2016-07-01

    A miniature fiber-optic Fabry-Perot interferometer fabricated by splicing a diaphragm-free hollow silica tube to a single-mode fiber and fusing the inner core to a taper is presented. The tapered zone forces lights to propagate from the fiber core into the silica tube, and the lights is reflected from the end faces of the optical fiber and the hollow silica tube. The contrast ratio of the interference fringe is determined by the minimum inner diameter of hollow silica tube. The responses of the proposed interferometer to high-temperature, gas refractive index, liquid refractive index and pressure were measured and were found to be linear with sensitivities of 16.26 pm/°C, 610.47 nm/RIU, -122.36 dB/RIU and 1.56 pm/kPa, respectively.

  17. A linker peptide with high affinity towards silica-containing materials.

    PubMed

    Sunna, Anwar; Chi, Fei; Bergquist, Peter L

    2013-06-25

    A peptide sequence with affinity to silica-containing materials was fused to a truncated form of Streptococcus strain G148 Protein G. The resulting recombinant Linker-Protein G (LPG) was produced in Escherichia coli and purified to apparent homogeneity. It displayed high affinity towards two natural clinoptilolite zeolites. The LPG also displayed high binding affinity towards commercial-grade synthetic zeolite, silica and silica-containing materials. A commercial sample of the truncated Protein G and a basic protein, both without the linker, did not bind to natural or synthetic zeolites or silica. We conclude that the zeolite-binding affinity is mediated by the linker peptide sequence. As a consequence, these data may imply that the binding affinity is directed to the SiO2 component rather than to the atomic orientation on the zeolite crystal surface as previously assumed.

  18. Femtosecond Laser Micro- and Nanopatterning of the Fused Silica Tube to Enhance Capillary Effect

    NASA Astrophysics Data System (ADS)

    Kim, Youngseop; Sohn, Ik-Bu; Noh, Young-Chul

    2012-10-01

    Femtosecond lasers have considerable advantages over conventional lasers for micromachining of transparent materials, and here we use these advantages to fabricate a new type of glass capillary tube with micro- and nanopatterns on the inner surface of the tube. In terms of femtosecond laser patterning, we focused on the polarization state of the femtosecond laser and found that the variation of polarization affected the performance of capillary tubes, especially capillary rise and contact angle. We subsequently confirmed that the number of micropatterns and the direction of nanoripples most greatly affected the capillary rise.

  19. Exploration of the multiparameter space of nanosecond-laser damage growth in fused silica optics.

    PubMed

    Negres, Raluca A; Liao, Zhi M; Abdulla, Ghaleb M; Cross, David A; Norton, Mary A; Carr, Christopher W

    2011-08-01

    Historically, the rate at which laser-induced damage sites grow on the exit surface of SiO2 optics under subsequent illumination with nanosecond-laser pulses of any wavelength was believed to depend solely on laser fluence. We demonstrate here that much of the scatter in previous growth observations was due to additional parameters that were not previously known to affect growth rate, namely the temporal pulse shape and the size of a site. Furthermore, the remaining variability observed in the rate at which sites grow is well described in terms of Weibull statistics. The effects of site size and laser fluence may both be expressed orthogonally in terms of Weibull coefficients. In addition, we employ a clustering algorithm to explore the multiparameter growth space and expose average growth trends. Conversely, this analysis approach also identifies sites likely to exhibit growth rates outside the norm. The ability to identify which sites are likely to grow abnormally fast in advance of the manifestation of such behavior will significantly enhance the accuracy of predictive models over those based on average growth behaviors.

  20. Surface analysis of polished fused-silica laser lenses by ion-scattering spectrometry

    SciTech Connect

    Orvek, K.; Steward, S.A.

    1982-10-11

    New advances in high-powered glass lasers, particularly the NOVA system, have resulted in a need for lenses having higher damage threshold values than those now available. It is currently thought that surface contaminants on the lenses are responsible for initiating part of the damage. These contaminants are apparently introduced during the final polishing stages. In this study, we used ion-scattering spectrometry (ISS) to identify contaminants arising through the use of different polishing techniques. Five lenses were studied, each having undergone different polishing procedures. The first lens was not polished after receiving it from the manfacturer (No. 381). Ion microprobe data were available for this lens, and they were compared to ISS results. The second lens had been polished with rouge, a polishing compound no longer in use (No. 796). This sample served as a further check on the ISS results. The third lens was studied as received from the manufacturer - with no handling or cleaning (No. 802). The final two lenses had both been polished using high-purity ceria, cerium oxide (No. 800 and No. 801). The difference between these two was that No. 800 was polished using a nylon lap, and No. 801 was polished using pitch as a lap. The 800-series lenses were all made from the same batch, and constituted the major part of the investigation.

  1. Gas adsorption surface analysis of silane-coated fused amorphous silica

    SciTech Connect

    Horn, A.F.

    1996-12-31

    Certain types of high frequency electrical circuit substrates consist of copper foil clad PTFE (poly(tetrafluoroethylene)) composite dielectric material that is highly filled (>50 vol.%) with various ceramic powders. The ceramic powders are chosen primarily to modify the dielectric constant of the composite, but also function to reduce the composite`s coefficient of thermal expansion (CTE). The ceramic powders are frequently treated with organosilane coupling agents to reduce the composite water absorption. To be effective, the coupling agents must not significantly degrade at the high processing temperature of PTFE (>350{degrees}C). Phenyl-trimethoxysilane (PTMS) or silane mixtures containing a high fraction of PTMS are often used.

  2. Mechanism of mechanical fatigue of fused silica. Progress report, July 1-December 31, 1985

    SciTech Connect

    Tomozawa, M.

    1986-01-01

    The mechanical strength of glass is strongly influenced by crack geometry. In particular, the mechanism of mechanical fatigue of glasses is closely related to crack tip geometry and a different mechanism has to be invoked depending upon whether the crack tip is sharp or blunt; a sharp tip crack can simply propagate, but a blunt tip crack has to be sharpened before it can propagate. In order to investigate the possibility of a blunt crack tip, the following two experiments were conducted: (1) strengthening upon annealing of glasses with extended crack; and (2) kinetics of strength increase upon annealing in various atmospheres. From the results of these experiments, it was shown that the crack tip of glass becomes blunt upon annealing. The results suggest that the mechanical fatigue of some glasses involves crack initiation as well as crack growth.

  3. Mechanism of mechanical fatigue of fused silica: Progress report, January 1, 1986-November 30, 1986

    SciTech Connect

    Tomozawa, Minoru

    1986-12-01

    The mechanical strength of glass is strongly influenced by crack geometry. A different fatigue mechanism has to be invoked depending upon whether the crack tip is sharp or blunt; a sharp tip crack can simply propagate, but a blunt tip crack has to be sharpened before it can propagate. It was shown that the crack tip of glass becomes blunt upon annealing. Similarly, the formation if a blunt crack was demonstrated earlier for glass specimens treated in hot water. Next, effects of the crack tip blunting on both dynamic fatigue and static fatigue were investigated in various liquids. It was found that fatigue of specimens with sharp cracks can be explained by the slow crack growth model satisfactorily, but fatigue of specimens with blunt cracks involves the initiation of a sharp crack in addition to the crack propagation. In static fatigue this crack initiation was found to require a far longer time than the crack propagation does. Furthermore, it was found that sharp crack initiation from a blunt tip under subcritical stress is possible only in water and not in non-aqueous liquids. Microhardness of glass in various liquids was investigated, and it was discovered that water enters SiO/sub 2/ glass during indentation while non-aqueous liquids do not.

  4. Studies on Nonlinear Mechanisms of Excimer Laser Propagation in Fused Silica Fibers.

    DTIC Science & Technology

    1987-07-31

    a bandgap at 1.06 um and we have made prelimary measurements of nonlinear optical properties in Schottky barriers , which will be reported at 05A. The...DAYGLO pigmentss ) so that a visible image appeared in fluorescence on the back side of the screen. Our experi- KWrs X. uki, MWy Niudofffer, .d Elsa...fluorescent screen. A video camera focused to the back of the fluores- cent screen provided real-time images. However. variability in power from shot to

  5. Optical modulation study of repaired damage morphologies of fused silica by scalar diffraction theory

    NASA Astrophysics Data System (ADS)

    Li, Bo; Zhou, Qingyan; Jiang, Yong; Xiang, Xia; Liao, Wei; Jiang, Xiaolong; Wang, Haijun; Luan, Xiaoyu; Zheng, Wanguo; Yuan, Xiaodong

    2017-01-01

    The cone and Gaussian repaired damage craters are two typical morphologies induced by CO2 laser evaporation and nonevaporation technologies. The mathematical models are built for these two types of repaired craters, and the light modulation at 355 nm induced by the millimeter-scale repaired damage morphology is studied by scalar diffraction theory. The results show that the modulation of the Gaussian repaired morphology has one peak and then decreases with the increasing distance from 0 to 30 cm. While the modulation for cone repaired morphology remains stable after decreasing quickly with the increasing distance. When the horizontal radius increases, the modulation looks like a saw-tooth. However, the modulation has irregular variations for two kinds of morphologies with the increasing vertical depth. The simulated results agree well with experimental results. The horizontal and vertical dimensions, and downstream distance have different influences on the modulation. The risk of damage to downstream optical components can be suppressed to improve the stability of the optical system if the shape and size of repaired craters are well controlled and the positions of downstream optical components are selected appropriately.

  6. Light intensification effect of trailing indent crack in fused silica subsurface

    NASA Astrophysics Data System (ADS)

    Zhang, ChunLai; Xu, Ming; Wang, ChunDong

    2015-03-01

    A finite-difference time-domain algorithm was applied to solve Maxwell's equations to obtain the redistribution of an electromagnetic plane wave in the vicinity of a trailing indent crack (TIC). The roles of five geometrical parameters playing in light intensification were calculated numerically under the irradiation of a 355-nm normal incidence laser. The results show that the light intensity enhancements between the nearest neighbor pits were remarkable, which may lead to damage. The calculated results reveal that the light intensity enhancement factor ( LIEF) can be up to 11.2 when TIC is on the rear-surface. With the increase of the length as well as the depth of pits, LIEF increased. Conversely, with the increase of the axis of pits, LIEF gradually declined to a stable status. It was observed that there exists an optima width or gap, which enables LIEF to be increased dramatically and then decreased gently. By comparison, results suggest that the worst cases occur when the depth and the length are both very large, especially if the width equals to 2 l and the gap equals the width. This work provides a recommended theoretical criterion for defect inspection and classification.

  7. Capillary electrophoresis: Imaging of electroosmotic and pressure driven flow profiles in fused silica capillaries

    NASA Technical Reports Server (NTRS)

    Williams, George O., Jr.

    1996-01-01

    This study is a continuation of the summer of 1994 NASA/ASEE Summer Faculty Fellowship Program. This effort is a portion of the ongoing work by the Biophysics Branch of the Marshall Space Flight Center. The work has focused recently on the separation of macromolecules using capillary electrophoresis (CE). Two primary goals were established for the effort this summer. First, we wanted to use capillary electrophoresis to study the electrohydrodynamics of a sample stream. Secondly, there was a need to develop a methodology for using CE for separation of DNA molecules of various sizes. In order to achieve these goals we needed to establish a procedure for detection of a sample plug under the influence of an electric field Detection of the sample with the microscope and image analysis system would be helpful in studying the electrohydrodynamics of this stream under load. Videotaping this process under the influence of an electric field in real time would also be useful. Imaging and photography of the sample/background electrolyte interface would be vital to this study. Finally, detection and imaging of electroosmotic flow and pressure driven flow must be accomplished.

  8. Kinetics of silica polymerization

    SciTech Connect

    Weres, O.; Yee, A.; Tsao, L.

    1980-05-01

    The polymerization of silicic acid in geothermal brine-like aqueous solutions to produce amorphous silica in colloidal form has been studied experimentally and theoretically. A large amount of high quality experimental data has been generated over the temperature rang 23 to 100{sup 0}C. Wide ranges of dissolved silica concentration, pH, and sodium chloride concentration were covered. The catalytic effects of fluoride and the reaction inhibiting effects of aluminum and boron were studied also. Two basic processes have been separately studied: the formation of new colloidal particles by the homogeneous nucleation process and the deposition of dissolved silica on pre-existing colloidal particles. A rigorous theory of the formation of colloidal particles of amorphous silica by homogeneous nucleation was developed. This theory employs the Lothe-Pound formalism, and is embodied in the computer code SILNUC which quantitatively models the homogeneous nucleation and growth of colloidal silica particles in more than enough detail for practical application. The theory and code were extensively used in planning the experimental work and analyzing the data produced. The code is now complete and running in its final form. It is capable of reproducing most of the experimental results to within experimental error. It is also capable of extrapolation to experimentally inaccessible conditions, i.e., high temperatures, rapidly varying temperature and pH, etc.

  9. FUSE Observations of K--M Stars

    NASA Astrophysics Data System (ADS)

    Ake, T. B.; Dupree, A. K.; Linsky, J. L.; Harper, G. M.; Young, P. R.

    2000-12-01

    As part of the FUSE PI program, a representative sample of cool stars is being surveyed in the LWRS (30 x 30 arcsec) aperture. We report on recent observations of three late-type stars, AU Mic (HD 197481, M0 Ve), β Gem (HD 62509, K0 IIIb), and α Ori (HD 39801, M1-2 Ia--Iab). AU Mic and β Gem show strong emission lines of O VI 1032/1037 and C III 977/1176 and weaker lines of C II, N II, N III, S IV, Si III, Si IV, and perhaps Fe III. AU Mic has evidence of He II and S III emission, and β Gem shows S I emission. Differences are seen in line ratios and line profiles between these stars. In α Ori, these features are very weak or non-existent, and Fe II fluorescent lines in the 1100-1150 Å region, pumped by H I Lyman α , are present. Several emission lines are still unidentified in all spectra. Prospects for future cool star observations will be discussed. This work is based on data obtained for the Guaranteed Time Team by the NASA-CNES-CSA FUSE mission operated by the Johns Hopkins University. Financial support to U. S. participants has been provided by NASA contract NAS5-32985.

  10. Fused Reality for Enhanced Flight Test Capabilities

    NASA Technical Reports Server (NTRS)

    Bachelder, Ed; Klyde, David

    2011-01-01

    The feasibility of using Fused Reality-based simulation technology to enhance flight test capabilities has been investigated. In terms of relevancy to piloted evaluation, there remains no substitute for actual flight tests, even when considering the fidelity and effectiveness of modern ground-based simulators. In addition to real-world cueing (vestibular, visual, aural, environmental, etc.), flight tests provide subtle but key intangibles that cannot be duplicated in a ground-based simulator. There is, however, a cost to be paid for the benefits of flight in terms of budget, mission complexity, and safety, including the need for ground and control-room personnel, additional aircraft, etc. A Fused Reality(tm) (FR) Flight system was developed that allows a virtual environment to be integrated with the test aircraft so that tasks such as aerial refueling, formation flying, or approach and landing can be accomplished without additional aircraft resources or the risk of operating in close proximity to the ground or other aircraft. Furthermore, the dynamic motions of the simulated objects can be directly correlated with the responses of the test aircraft. The FR Flight system will allow real-time observation of, and manual interaction with, the cockpit environment that serves as a frame for the virtual out-the-window scene.

  11. Fusing Symbolic and Numerical Diagnostic Computations

    NASA Technical Reports Server (NTRS)

    James, Mark

    2007-01-01

    X-2000 Anomaly Detection Language denotes a developmental computing language, and the software that establishes and utilizes the language, for fusing two diagnostic computer programs, one implementing a numerical analysis method, the other implementing a symbolic analysis method into a unified event-based decision analysis software system for realtime detection of events (e.g., failures) in a spacecraft, aircraft, or other complex engineering system. The numerical analysis method is performed by beacon-based exception analysis for multi-missions (BEAMs), which has been discussed in several previous NASA Tech Briefs articles. The symbolic analysis method is, more specifically, an artificial-intelligence method of the knowledge-based, inference engine type, and its implementation is exemplified by the Spacecraft Health Inference Engine (SHINE) software. The goal in developing the capability to fuse numerical and symbolic diagnostic components is to increase the depth of analysis beyond that previously attainable, thereby increasing the degree of confidence in the computed results. In practical terms, the sought improvement is to enable detection of all or most events, with no or few false alarms.

  12. Spectral fusing Gabor domain optical coherence microscopy.

    PubMed

    Meemon, Panomsak; Widjaja, Joewono; Rolland, Jannick P

    2016-02-01

    Gabor domain optical coherence microscopy (GD-OCM) is one of many variations of optical coherence tomography (OCT) techniques that aims for invariant high resolution across a 3D field of view by utilizing the ability to dynamically refocus the imaging optics in the sample arm. GD-OCM acquires multiple cross-sectional images at different focus positions of the objective lens, and then fuses them to obtain an invariant high-resolution 3D image of the sample, which comes with the intrinsic drawback of a longer processing time as compared to conventional Fourier domain OCT. Here, we report on an alternative Gabor fusing algorithm, the spectral-fusion technique, which directly processes each acquired spectrum and combines them prior to the Fourier transformation to obtain a depth profile. The implementation of the spectral-fusion algorithm is presented and its performance is compared to that of the prior GD-OCM spatial-fusion approach. The spectral-fusion approach shows twice the speed of the spatial-fusion approach for a spectrum size of less than 2000 point sampling, which is a commonly used spectrum size in OCT imaging, including GD-OCM.

  13. Monolithic silica capillary columns with immobilized cellulose tris(3,5-dimethylphenylcarbamate) for enantiomer separations in CEC.

    PubMed

    He, Chiyang; Hendrickx, Ans; Mangelings, Debby; Smeyers-Verbeke, Johanna; Vander Heyden, Yvan

    2009-11-01

    Two types of monolithic silica capillary columns with an immobilized cellulose tris(3,5-dimethylphenylcarbamate) (CDMPC) selector were prepared for enantiomer separations in CEC. The monolithic columns were prepared by a sol-gel process in fused-silica capillaries. CDMPC was then either immobilized on a silica monolith through an intermolecular polycondensation of the cellulose derivative containing a triethoxysilyl group, or on a vinylized silica monolith through radical copolymerization of the cellulose derivative, which also contained a vinyl group. IR spectra confirmed the successful immobilization of CDMPC on both columns. Eleven chiral compounds were used to evaluate the enantioselectivity on both column types. Results indicated that the columns obtained via polycondensation had higher separation ability than those obtained via radical polymerization, and that they showed satisfactory run-to-run repeatability and stability. These new techniques thus provide strategies for preparing immobilized polysaccharide-based chiral silica monolithic capillary columns for chiral separations by means of CEC.

  14. Silica Precipitation and Lithium Sorption

    SciTech Connect

    Jay Renew

    2015-09-20

    This file contains silica precipitation and lithium sorption data from the project. The silica removal data is corrected from the previous submission. The previous submission did not take into account the limit of detection of the ICP-MS procedure.

  15. Femtosecond laser-induced periodic surface structures on silica

    SciTech Connect

    Hoehm, S.; Rosenfeld, A.; Krueger, J.; Bonse, J.

    2012-07-01

    The formation of laser-induced periodic surface structures (LIPSS) on two different silica polymorphs (single-crystalline synthetic quartz and commercial fused silica glass) upon irradiation in air with multiple linearly polarized single- and double-fs-laser pulse sequences ({tau} = 150 fs pulse duration, {lambda} = 800 nm center wavelength, temporal pulse separation {Delta}t < 40 ps) is studied experimentally and theoretically. Two distinct types of fs-LIPSS [so-called low-spatial-frequency LIPSS (LSFL) and high-spatial-frequency LIPSS (HSFL)] with different spatial periods and orientations were identified. Their appearance was characterized with respect to the experimental parameters peak laser fluence and number of laser pulses per spot. Additionally, the 'dynamics' of the LIPSS formation was addressed in complementary double-fs-pulse experiments with varying delays, revealing a characteristic change of the LSFL periods. The experimental results are interpreted on the basis of a Sipe-Drude model considering the carrier dependence of the optical properties of fs-laser excited silica. This new approach provides an explanation of the LSFL orientation parallel to the laser beam polarisation in silica - as opposed to the behaviour of most other materials.

  16. Comparison of monolithic silica and polymethacrylate capillary columns for LC.

    PubMed

    Moravcová, Dana; Jandera, Pavel; Urban, Jiri; Planeta, Josef

    2004-07-01

    Organic polymer monolithic capillary columns were prepared in fused-silica capillaries by radical co-polymerization of ethylene dimethacrylate and butyl methacrylate monomers with azobisisobutyronitrile as initiator of the polymerization reaction in the presence of various amounts of porogenic solvent mixtures and different concentration ratios of monomers and 1-propanol, 1,4-butanediol, and water. The chromatographic properties of the organic polymer monolithic columns were compared with those of commercial silica-based particulate and monolithic capillary and analytical HPLC columns. The tests included the determination of H-u curves, column permeabilities, pore distribution by inversed-SEC measurements, methylene and polar selectivities, and polar interactions with naphthalenesulphonic acid test samples. Organic polymer monolithic capillary columns show similar retention behaviour to chemically bonded alkyl silica columns for compounds with different polarities characterized by interaction indices, Ix, but have lower methylene selectivities and do not show polar interactions with sulphonic acids. The commercial capillary and analytical silica gel-based monolithic columns showed similar selectivities and provided symmetrical peaks, indicating no significant surface heterogeneities. To allow accurate characterization of the properties of capillary monolithic columns, the experimental data should be corrected for extra-column contributions. With 0.3 mm ID capillary columns, corrections for extra-column volume contributions are sufficient, but to obtain true information on the efficiency of 0.1 mm ID capillary columns, the experimental bandwidths should be corrected for extra-column contributions to peak broadening.

  17. Epoxy Grout With Silica Thickener

    NASA Technical Reports Server (NTRS)

    Mcclung, C. E.

    1984-01-01

    Grout cures quickly, even in presence of hydraulic oil. Grout is mixture of aggregate particles, finely-divided silica, epoxy resin, and triethylenetetramine curing agent, with mixture containing about 85 percent silica and aggregate particle sand 15 percent resin and curing agent. Silica is thickening agent and keeps grout from sagging.

  18. Development of a fused slurry silicide coating for the protection of tantalum alloys

    NASA Technical Reports Server (NTRS)

    Packer, C. M.; Perkins, R. A.

    1974-01-01

    Results are reported of a research program to develop a reliable high-performance, fused slurry silicide protective coating for a tantalum-10 tungsten alloy for use at 1427 to 1538 C at 0.1 to 10 torr air pressure under cyclic temperature conditions. A review of silicide coating performance under these conditions indicated that the primary wear-out mode is associated with widening of hairline fissures in the coating. Consideration has been given to modifying the oxidation products that form on the coating surface to provide a seal for these fissures and to minimize their widening. On the basis of an analysis of the phase relationships between silica and various other oxides, a coating having the slurry composition 2.5Mn-33Ti-64.5Si was developed that is effective in the pressure range from 1 to 10 torr.

  19. Thermal stress analysis of fused-cast AZS refractories during production; Part 1: Industrial study

    SciTech Connect

    Cockcroft, S.L.; Brimacombe, J.K. . Centre for Metallurgical Process Engineering); Walrod, D.G.; Myles, T.A. . Monofrax-S Plant)

    1994-06-01

    A study has been conducted to understand and prevent the formation of cracks in alumina-zirconia-silica (AZS) refractory blocks during solidification processing. A fundamental approach has been taken, centered on the development of a three-dimensional mathematical model to predict heat flow and stress generation in fused-cast AZS refractory blocks. In the first part of a two-part study, the voidless'' casting process has been carefully examined in an industrial setting. From a survey of the distribution, frequency of occurrence, and fracture surface morphology of cracks, an attempt was made to link the crack types found in the study to process variables. In-mold temperature data collected for a single casting throughout the normal cooling period have been used to validate the heat-flow model which is described in Part 2. The stress analysis, cause of the different cracks, and remedial action are also presented in Part 2.

  20. Understanding error generation in fused deposition modeling

    NASA Astrophysics Data System (ADS)

    Bochmann, Lennart; Bayley, Cindy; Helu, Moneer; Transchel, Robert; Wegener, Konrad; Dornfeld, David

    2015-03-01

    Additive manufacturing offers completely new possibilities for the manufacturing of parts. The advantages of flexibility and convenience of additive manufacturing have had a significant impact on many industries, and optimizing part quality is crucial for expanding its utilization. This research aims to determine the sources of imprecision in fused deposition modeling (FDM). Process errors in terms of surface quality, accuracy and precision are identified and quantified, and an error-budget approach is used to characterize errors of the machine tool. It was determined that accuracy and precision in the y direction (0.08-0.30 mm) are generally greater than in the x direction (0.12-0.62 mm) and the z direction (0.21-0.57 mm). Furthermore, accuracy and precision tend to decrease at increasing axis positions. The results of this work can be used to identify possible process improvements in the design and control of FDM technology.

  1. Itinerant Conductance in Fuse-Antifuse Networks

    NASA Astrophysics Data System (ADS)

    Filho, Cesar I. N. Sampaio; Moreira, André A.; Araújo, Nuno A. M.; Andrade, José S.; Herrmann, Hans J.

    2016-12-01

    We report on a novel dynamic phase in electrical networks, in which current channels perpetually change in time. This occurs when the elementary units of the network are fuse-antifuse devices, namely, become insulators within a certain finite interval of local applied voltages. As a consequence, the macroscopic current exhibits temporal fluctuations which increase with system size. We determine the conditions under which this exotic situation appears by establishing a phase diagram as a function of the applied field and the size of the insulating window. Besides its obvious application as a versatile electronic device, due to its rich variety of behaviors, this network model provides a possible description for particle-laden flow through porous media leading to dynamical clogging and reopening of the local channels in the pore space.

  2. FUSE Observations of Luminous Cool Stars

    NASA Astrophysics Data System (ADS)

    Dupree, A. K.; Young, P. R.; Ake, T. B.

    2000-12-01

    Luminous cool stars can address the evolution of magnetic activity and the dynamics of stellar winds and mass loss. The region of yellow supergiants in the HR diagram contains stars of intermediate mass both with coronas and those possessing a hot outer atmosphere in the presence of a strong wind (the ``hybrid'' stars). These hybrid objects hold particular significance for evolution studies because they represent the physically important connection between solar-like stars (with coronas and fast winds of low-mass loss rate) and the cool supergiant stars (Alpha Ori-like) with cool outer atmospheres and massive winds. The Far Ultraviolet Spectroscopic Explorer (FUSE) measured the chromospheric and transition region emissions of the bright G2 Ib supergiant Beta Draconis (HD 159181) on 9 May 2000. Two exposures through the large aperture totaled 7695 s and were obtained in all channels covering the region λ λ 912-1180. Emission from chromospheric and transition region ions (C III, O VI, Si III, S IV, S VI) is detected along with a number of low ion stages. Profiles of strong lines are asymmetric suggesting the presence of a wind. A short exposure (3260 s) of Alpha Aquarii (HD 209750), a hybrid supergiant also of spectral type G2 Ib was obtained June 29, 2000. Dynamics of the atmospheres can be inferred from line profiles. The atmospheric temperature distribution, densities, and scale sizes can be evaluated from line fluxes to characterize the differences between a coronal star and a hybrid supergiant. FUSE is a NASA Origins mission operated by The Johns Hopkins University. Funding for this research is provided through NASA Contract NAS-532985.

  3. High Voltage Applications of Explosively Formed Fuses

    NASA Astrophysics Data System (ADS)

    Tasker, D. G.; Goforth, J. H.; Fowler, C. M.; Herrera, D. H.; King, J. C.; Lopez, E. A.; Martinez, E. C.; Oona, H.; Marsh, S. P.; Reinovsky, R. E.; Stokes, J.; Tabaka, L. J.; Torres, D. T.; Sena, F. C.; Kiuttu, G.; Degnan, J.

    2004-11-01

    At Los Alamos, we have primarily applied Explosively Formed Fuse (EFF) techniques to high current systems. In these systems, the EFF has interrupted currents from 19-25 MA, thus diverting the current to low inductance loads. The transferred current magnitude is determined by the ratio of storage inductance to load inductance and, with dynamic loads, the current has ranged from 12-20 MA. In a system with 18 MJ stored energy, the switch operates at a power of up to 6 TW. We are now investigating the use of the EFF technique to apply high voltages to high impedance loads in systems that are more compact. In these systems we are exploring circuits with EFF lengths from 43-100 cm, which have storage inductances large enough to apply 300-500 kV across high impedance loads. Experimental results and design considerations are presented. Using cylindrical EFF switches of 10 cm diameter and 43 cm length, currents of approximately 3 MA were interrupted producing ~200 kV. This indicates the switch had an effective resistance of ~100 mΩ where 150-200 mΩ was expected. To understand the lower performance, several parameters were studied including electrical conduction through the explosive products; current density; explosive initiation; insulator type and conductor thickness. The results show a number of interesting features, most notably that the primary mechanism of switch operation is mechanical and not electrical fusing of the conductor. Switches opening on a 1-10 μs time scale with resistances starting at 50 μΩ and increasing to perhaps 1 Ω now seem possible to construct using explosive charges as small as a few pounds.

  4. High Voltage Application of Explosively Formed Fuses

    SciTech Connect

    Tasker, D.G.; Goforth, J.H.; Fowler, C.M.; Lopez, E.M.; Oona, H.; Marsh, S.P.; King, J.C.; Herrera, D.H.; Torres, D.T.; Sena, F.C.; Martinez, E.C.; Reinovsky, R.E.; Stokes, J.L.; Tabaka, L.J.; Kiuttu, G.; Degnan, J.

    1998-10-18

    At Los Alamos, the authors have primarily applied Explosively Formed Fuse (EFF) techniques to high current systems. In these systems, the EFF has interrupted currents from 19 to 25 MA, thus diverting the current to low inductance loads. The magnitude of transferred current is determined by the ratio of storage inductance to load inductance, and with dynamic loads, the current has ranged from 12 to 20 MA. In a system with 18 MJ stored energy, the switch operates at a power up to 6 TW. The authors are now investigating the use of the EFF technique to apply high voltages to high impedance loads in systems that are more compact. In these systems, they are exploring circuits with EFF lengths from 43 to 100 cm, which have storage inductances large enough to apply 300 to 500 kV across high impedance loads. Experimental results and design considerations are presented. Using cylindrical EFF switches of 10 cm diameter and 43 cm length, currents of approximately 3 MA were interrupted producing {approximately}200 kV. This indicate s the switch had an effective resistance of {approximately}100 m{Omega} where 150--200 m{Omega} was expected. To understand the lower performance, several parameters were studied, including: electrical conduction through the explosive products; current density; explosive initiation; insulator type; conductor thickness; and so on. The results show a number of interesting features, most notably that the primary mechanism of switch operation is mechanical and not electrical fusing of the conductor. Switches opening on a 10 to 10 {micro}s time scale with resistances starting at 50 {micro}{Omega} and increasing to perhaps 1 {Omega} now seem possible to construct, using explosive charges as small as a few pounds.

  5. 78 FR 14540 - Cyromazine, Silica Silicates (Silica Dioxide and Silica Gel), Glufosinate Ammonium, Dioctyl...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-06

    ... AGENCY Cyromazine, Silica Silicates (Silica Dioxide and Silica Gel), Glufosinate Ammonium, Dioctyl Sodium... ammonium, dioctyl sodium sulfosuccinate (DSS) and undecylenic acid (UDA) and opens a public comment period...-HQ-OPP-2006-0108... Kelly Ballard, (703) 305-8126, Ballard.kelly@epa.gov . Dioctyl...

  6. 29 CFR 1926.907 - Use of safety fuse.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... destroyed. (f) No fuse shall be capped, or primers made up, in any magazine or near any possible source of ignition. (g) No one shall be permitted to carry detonators or primers of any kind on his person. (h) The...-called “drop fuse” method of dropping or pushing a primer or any explosive with a lighted fuse...

  7. 29 CFR 1926.907 - Use of safety fuse.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... destroyed. (f) No fuse shall be capped, or primers made up, in any magazine or near any possible source of ignition. (g) No one shall be permitted to carry detonators or primers of any kind on his person. (h) The...-called “drop fuse” method of dropping or pushing a primer or any explosive with a lighted fuse...

  8. Influence of silk-silica fusion protein design on silica condensation in vitro and cellular calcification

    PubMed Central

    Plowright, Robyn; Dinjaski, Nina; Zhou, Shun; Belton, David J.; Kaplan, David L.; Perry, Carole C.

    2016-01-01

    Biomaterial design via genetic engineering can be utilized for the rational functionalization of proteins to promote biomaterial integration and tissue regeneration. Spider silk has been extensively studied for its biocompatibility, biodegradability and extraordinary material properties. As a protein-based biomaterial, recombinant DNA derived derivatives of spider silks have been modified with biomineralization domains which lead to silica deposition and potentially accelerated bone regeneration. However, the influence of the location of the R5 (SSKKSGSYSGSKGSKRRIL) silicifying domain fused with the spider silk protein sequence on the biosilicification process remains to be determined. Here we designed two silk-R5 fusion proteins that differed in the location of the R5 peptide, C- vs. N-terminus, where the spider silk domain consisted of a 15mer repeat of a 33 amino acid consensus sequence of the major ampullate dragline Spidroin 1 from Nephila clavipes (SGRGGLGGQG AGAAAAAGGA GQGGYGGLGSQGT). The chemical, physical and silica deposition properties of these recombinant proteins were assessed and compared to a silk 15mer control without the R5 present. The location of the R5 peptide did not have a significant effect on wettability and surface energies, while the C-terminal location of the R5 promoted more controlled silica precipitation, suggesting differences in protein folding and possibly different access to charged amino acids that drive the silicification process. Further, cell compatibility in vitro, as well as the ability to promote human bone marrow derived mesenchymal stem cell (hMSC) differentiation were demonstrated for both variants of the fusion proteins. PMID:26989487

  9. Application of volcanic ash particles for protein affinity purification with a minimized silica-binding tag.

    PubMed

    Abdelhamid, Mohamed A A; Ikeda, Takeshi; Motomura, Kei; Tanaka, Tatsuya; Ishida, Takenori; Hirota, Ryuichi; Kuroda, Akio

    2016-11-01

    We recently reported that the spore coat protein, CotB1 (171 amino acids), from Bacillus cereus mediates silica biomineralization and that the polycationic C-terminal sequence of CotB1 (14 amino acids), designated CotB1p, serves as a silica-binding tag when fused to other proteins. Here, we reduced the length of this silica-binding tag to only seven amino acids (SB7 tag: RQSSRGR) while retaining its affinity for silica. Alanine scanning mutagenesis indicated that the three arginine residues in the SB7 tag play important roles in binding to a silica surface. Monomeric l-arginine, at concentrations of 0.3-0.5 M, was found to serve as a competitive eluent to release bound SB7-tagged proteins from silica surfaces. To develop a low-cost, silica-based affinity purification procedure, we used natural volcanic ash particles with a silica content of ∼70%, rather than pure synthetic silica particles, as an adsorbent for SB7-tagged proteins. Using green fluorescent protein, mCherry, and mKate2 as model proteins, our purification method achieved 75-90% recovery with ∼90% purity. These values are comparable to or even higher than that of the commonly used His-tag affinity purification. In addition to low cost, another advantage of our method is the use of l-arginine as the eluent because its protein-stabilizing effect would help minimize alteration of the intrinsic properties of the purified proteins. Our approach paves the way for the use of naturally occurring materials as adsorbents for simple, low-cost affinity purification.

  10. Silica colloidal crystals as porous substrates for total internal reflection fluorescence microscopy of live cells.

    PubMed

    Velarde, Tomika R C; Wirth, Mary J

    2008-06-01

    Total internal reflection fluorescence (TIRF) microscopy is a powerful means of probing biological cells because it reduces autofluorescence, but the need for direct contact between the cell surface and the microscope slide hinders chemical access to the cell surface. In this work, a submicrometer crystalline layer of colloidal silica on the microscope coverslip is shown to allow TIRF microscopy while also allowing chemical access to the cell surface. A 750 nm layer of 165 nm silica colloidal crystals was sintered onto a fused silica coverslip, and Chinese hamster ovary cells were successfully grown on this surface. This cell line over-expresses the human delta-opioid receptor, which enabled probing of the binding of a labeled ligand to the receptors on the cell surface. Total internal reflection and chemical access to the cell surface are demonstrated. The range of angles for total internal reflection is reduced only by 1/3 due to the lower index of refraction of the colloidal multilayer relative to fused silica.

  11. The world ocean silica cycle.

    PubMed

    Tréguer, Paul J; De La Rocha, Christina L

    2013-01-01

    Over the past few decades, we have realized that the silica cycle is strongly intertwined with other major biogeochemical cycles, like those of carbon and nitrogen, and as such is intimately related to marine primary production, the efficiency of carbon export to the deep sea, and the inventory of carbon dioxide in the atmosphere. For nearly 20 years, the marine silica budget compiled by Tréguer et al. (1995) , with its exploration of reservoirs, processes, sources, and sinks in the silica cycle, has provided context and information fundamental to study of the silica cycle. Today, the budget needs revisiting to incorporate advances that have notably changed estimates of river and groundwater inputs to the ocean of dissolved silicon and easily dissolvable amorphous silica, inputs from the dissolution of terrestrial lithogenic silica in ocean margin sediments, reverse weathering removal fluxes, and outputs of biogenic silica (especially on ocean margins and in the form of nondiatomaceous biogenic silica). The resulting budget recognizes significantly higher input and output fluxes and notes that the recycling of silicon occurs mostly at the sediment-water interface and not during the sinking of silica particles through deep waters.

  12. Infrared spectra of silica polymorphs and the conditions of their formation

    SciTech Connect

    Koike, C.; Noguchi, R.; Ohtaka, O.; Imai, Y.; Matsumoto, T.; Chihara, H.; Tsuchiyama, A.; Suto, H.

    2013-11-20

    The existence of silica within several debris disks has been suggested. Data on both the spectroscopy and annealing conditions of the various polymorphs of silica need to be investigated, as these data are lacking and incomplete in the literature. We investigate the annealing conditions of silica and prepare various types of silica, including α-cristobalite, α-quartz, coesite, stishovite, and fused quartz, which are natural, synthetic, or commercial samples. This paper presents a new study of both the spectroscopy of relevant silica polymorphs and the conditions under which they form. We compare the results to previous studies and find that there are discrepancies. The interesting result of features similar to those of forsterite should be highlighted, where α-cristobalite and coesite showed similar peaks at 16, 33, and 69 μm as forsterite. The 69 μm band for α-cristobalite is especially very broad and strong and shifts largely to a shorter wavelengths under cooling to low temperatures. The band for coesite, however, is very sharp and shifts only a small amount to longer wavelengths under cooling to low temperatures. We discuss the possibility of silica detection around debris disks.

  13. Infrared Spectra of Silica Polymorphs and the Conditions of Their Formation

    NASA Astrophysics Data System (ADS)

    Koike, C.; Noguchi, R.; Chihara, H.; Suto, H.; Ohtaka, O.; Imai, Y.; Matsumoto, T.; Tsuchiyama, A.

    2013-11-01

    The existence of silica within several debris disks has been suggested. Data on both the spectroscopy and annealing conditions of the various polymorphs of silica need to be investigated, as these data are lacking and incomplete in the literature. We investigate the annealing conditions of silica and prepare various types of silica, including α-cristobalite, α-quartz, coesite, stishovite, and fused quartz, which are natural, synthetic, or commercial samples. This paper presents a new study of both the spectroscopy of relevant silica polymorphs and the conditions under which they form. We compare the results to previous studies and find that there are discrepancies. The interesting result of features similar to those of forsterite should be highlighted, where α-cristobalite and coesite showed similar peaks at 16, 33, and 69 μm as forsterite. The 69 μm band for α-cristobalite is especially very broad and strong and shifts largely to a shorter wavelengths under cooling to low temperatures. The band for coesite, however, is very sharp and shifts only a small amount to longer wavelengths under cooling to low temperatures. We discuss the possibility of silica detection around debris disks.

  14. Biofunctionalization of silica-coated magnetic particles mediated by a peptide

    NASA Astrophysics Data System (ADS)

    Care, Andrew; Chi, Fei; Bergquist, Peter L.; Sunna, Anwar

    2014-08-01

    A linker peptide sequence with affinity to silica-containing materials was fused to Streptococcus protein G', an antibody-binding protein. This recombinant fusion protein, linker-protein G (LPG) was produced in E. coli and exhibited strong affinity to silica-coated magnetic particles and was able to bind to them at different pHs, indicating a true pH-independent binding. LPG was used as an anchorage point for the oriented immobilization of antibodies onto the surface of the particles. These particle-bound "LPG-Antibody complexes" mediated the binding and recovery of different cell types (e.g., human stem cells, Legionella, Cryptosporidium and Giardia), enabling their rapid and simple visualization and identification. This strategy was used also for the efficient capture of Cryptosporidium oocysts from water samples. These results demonstrate that LPG can mediate the direct biofunctionalization of silica-coated magnetic particles without the need for complex surface chemical modification.

  15. Optical absorption of neutron-irradiated silica fibers

    SciTech Connect

    Cooke, D.W.; Farnum, E.H.; Bennett, B.L.

    1996-10-01

    Induced-loss spectra of silica-based optical fibers exposed to high (10{sup 23} n-m{sup {minus}2}) and low (10{sup 21} n-m{sup {minus}2}) fluences of neutrons at the Los Alamos Spallation Radiation Effects Facility (LASREF) have been measured. Two types of fibers consisting of a pure fused silica core with fluorine-doped ({approximately}4 mole %) cladding were obtained from Fiberguide Industries and used in the as-received condition. Anhydroguide{trademark} and superguide{trademark} fibers contained less than 1 ppm, and 600 to 800 ppm of OH, respectively. The data suggest that presently available silica fibers can be used in plasma diagnostics, but the choice and suitability depends upon the spectral region of interest. Low-OH content fibers can be used for diagnostic purposes in the interval {approximately}800 to 1400 mn if the exposure is to high-fluence neutrons. For low-fluence neutron exposures, the low-OH content fibers are best suited for use in the interval {approximately}800 to 2000 nm, and the high-OH content fibers are the choice for the interval {approximately}400 to 800 nm.

  16. Photopolymerization of acrylamide as a new functionalization way of silica monoliths for hydrophilic interaction chromatography and coated silica capillaries for capillary electrophoresis.

    PubMed

    El-Debs, R; Marechal, A; Dugas, V; Demesmay, C

    2014-01-24

    A simple, rapid and localizable photochemical process for the preparation of hydrophilic coated capillary and silica-based monolithic capillary columns is described. The process involves the free radical polymerization of acrylamide monomers onto acrylate pre-activated silica surface triggered by UV photoinitiation. The experimental conditions (monomer content, time of irradiation) were optimized on silica monolithic columns by monitoring the evolution of the chromatographic properties (retention, permeability, efficiency) in HILIC mode using a set of nucleosides as test solutes. Compared to thermal polymerization process, the photoinitiation allows the preparation of highly retentive and efficient HILIC monolithic columns in less than 10min of irradiation. This process was then successfully applied to the surface coating of fused silica capillary walls. In addition to its relative high stability and ability to reduce the electroosmotic flow, this polyacrylamide coating is localizable. Benefits of this localizable photochemical process are highlighted through the conception of an in-line integrated bimodal microseparation tool combining a SPE preconcentration step on a photografted silica monolith and an electrokinetic separation step in a polyacrylamide photopolymerized capillary section. Two neuropeptides are used as model solutes to illustrate the suitability of this approach.

  17. Radiation Effects on Fused Biconical Taper Wavelength Division Multiplexers

    NASA Technical Reports Server (NTRS)

    Gutierrez, Roman C.; Swift, Gary M.; Dubovitsky, Serge; Bartman, Randall K.; Barnes, Charles E.; Dorsky, Leonard

    1994-01-01

    The effects of radiation on fused biconical taper wavelength division multiplexers are presented. A theoretical model indicates that index changes in the fiber are primarily responsible for the degradation of these devices.

  18. Astronaut Hoffman replaces fuse plugs on Hubble Space Telescope

    NASA Technical Reports Server (NTRS)

    1993-01-01

    Astronaut Jeffrey A. Hoffman sees to the replacement of fuse plugs on the Hubble Space Telescope (HST) during the first of five space walks. Thunderclouds are all that is visible on the dark earth in the background.

  19. Technical report on galvanic cells with fused-salt electrolytes

    NASA Technical Reports Server (NTRS)

    Cairns, E. J.; Crouthamel, C. E.; Fischer, A. K.; Foster, M. S.; Hesson, J. C.; Johnson, C. E.; Shimotake, H.; Tevebaugh, A. D.

    1969-01-01

    Technical report is presented on sodium and lithium cells using fused salt electrolytes. It includes a discussion of the thermally regenerative galvanic cell and the secondary bimetallic cell for storage of electricity.

  20. Fused liposome and acid induced method for liposome fusion

    SciTech Connect

    Huang, L.; Connor, J.

    1988-12-06

    This patent describes a method of fusing liposomes. It comprises: preparing a suspension of liposomes containing at least one lipid which has a tendency to form the inverted hexagonal phase and at least 20 mol percent of palmitoylhomocysteine; and in the absence of externally added divalent cations, proteins or other macromolecules, acidifying the liposome suspension to reduce the pH of the liposomes to below pH 7, such that at least about 20% of the liposomes fuse to one another.

  1. Fusing Manual and Machine Feedback in Biomedical Domain

    DTIC Science & Technology

    2014-11-01

    Fusing manual and machine feedback in biomedical domain 1Jainisha Sankhavara, 1Fenny Thakrar, 2Shamayeeta Sarkar, 1Prasenjit Majumder 1DA-IICT...to obtain efficient biomedical document retrieval. We focused on fusing manual and machine feedback runs. Fusion run performs better and gives... feedback was used (top 5 documents were manually judged). we have applied two types of fusions: CombSUM and Z fusion [1] [2]. After the relevance

  2. Silica Fillers for elastomer Reinforement

    SciTech Connect

    Kohls, D.J.; Schaefer, D.W.

    2009-08-26

    This article summarizes recent work on the structure of precipitated silica used in the reinforcement of elastomers. Silica has a unique morphology, consisting of multiple structural levels that can be controlled through processing. The ability to control and characterize the multiple structures of precipitated silica is an example of morphological engineering for reinforcement applications. In this summary of some recent research efforts using precipitated silica, small-angle scattering techniques are described and their usefulness for determining the morphology of silica in terms of primary particles, aggregates, and agglomerates are discussed. The structure of several different precipitated silica powders is shown as well as the mechanical properties of elastomers reinforced with these silica particles. The study of the mechanical properties of filled elastomer systems is a challenging and exciting topic for both fundamental science and industrial application. It is known that the addition of hard particulates to a soft elastomer matrix results in properties that do not follow a straightforward rule of mixtures. Research efforts in this area have shown that the properties of filled elastomers are influenced by the nature of both the filler and the matrix, as well as the interactions between them. Several articles have reviewed the influence of fillers like silica and carbon black on the reinforcement of elastomers. In general, the structure-property relationships developed for filled elastomers have evolved into the following major areas: Filler structure, hydrodynamic reinforcement, and interactions between fillers and elastomers.

  3. Silica Fillers for elastomer Reinforement

    SciTech Connect

    Kohls, D.J.; Schaefer, D.W.

    2012-09-10

    This article summarizes recent work on the structure of precipitated silica used in the reinforcement of elastomers. Silica has a unique morphology, consisting of multiple structural levels that can be controlled through processing. The ability to control and characterize the multiple structures of precipitated silica is an example of morphological engineering for reinforcement applications. In this summary of some recent research efforts using precipitated silica, small-angle scattering techniques are described and their usefulness for determining the morphology of silica in terms of primary particles, aggregates, and agglomerates are discussed. The structure of several different precipitated silica powders is shown as well as the mechanical properties of elastomers reinforced with these silica particles. The study of the mechanical properties of filled elastomer systems is a challenging and exciting topic for both fundamental science and industrial application. It is known that the addition of hard particulates to a soft elastomer matrix results in properties that do not follow a straightforward rule of mixtures. Research efforts in this area have shown that the properties of filled elastomers are influenced by the nature of both the filler and the matrix, as well as the interactions between them. Several articles have reviewed the influence of fillers like silica and carbon black on the reinforcement of elastomers. In general, the structure-property relationships developed for filled elastomers have evolved into the following major areas: Filler structure, hydrodynamic reinforcement, and interactions between fillers and elastomers.

  4. Peptide -- Silica Hybrid Networks

    NASA Astrophysics Data System (ADS)

    Altunbas, Aysegul; Sharma, Nikhil; Nagarkar, Radhika; Schneider, Joel; Pochan, Darrin

    2010-03-01

    In this study, a bio-inspired route was used to fabricate scaffolds that display hierarchical organization of an inorganic layer around an organic self-assembled peptide fibril template. The 20 amino acid peptide used in this study intramolecular folds into a beta-hairpin conformation on addition of a desired solution stimulus. This intramolecular folding is followed by intermolecular self-assembly of the peptides into a three dimensional network of entangled fibrils rich in beta-sheet with a high density of lysine groups exposed on the fibril-surfaces. The lysine-rich surface chemistry was utilized to create a silica shell around the fibrils. The mineralization process of the fibrils results in a rigid, porous silica network that retains the microscale and nanoscale structure of the peptide fibril network. Structural characterization via Transmission Electron Microscopy, cryogenic-Scanning Electron Microscopy, mechanical characterization via oscillatory rheology, Small Angle X-ray and Neutron Scattering of the silicified hydrogels will be presented.

  5. Silaffins in Silica Biomineralization and Biomimetic Silica Precipitation

    PubMed Central

    Lechner, Carolin C.; Becker, Christian F. W.

    2015-01-01

    Biomineralization processes leading to complex solid structures of inorganic material in biological systems are constantly gaining attention in biotechnology and biomedical research. An outstanding example for biomineral morphogenesis is the formation of highly elaborate, nano-patterned silica shells by diatoms. Among the organic macromolecules that have been closely linked to the tightly controlled precipitation of silica in diatoms, silaffins play an extraordinary role. These peptides typically occur as complex posttranslationally modified variants and are directly involved in the silica deposition process in diatoms. However, even in vitro silaffin-based peptides alone, with and without posttranslational modifications, can efficiently mediate biomimetic silica precipitation leading to silica material with different properties as well as with encapsulated cargo molecules of a large size range. In this review, the biomineralization process of silica in diatoms is summarized with a specific focus on silaffins and their in vitro silica precipitation properties. Applications in the area of bio- and nanotechnology as well as in diagnostics and therapy are discussed. PMID:26295401

  6. Imaging VISAR diagnostic for the National Ignition Facility (NIF)

    SciTech Connect

    Malone, R M; Bower, J R; Bradley, D K; Capelle, G A; Celeste, J R; Celliers, P M; Collins, G W; Eckart, M J; Eggert, J H; Frogget, B C; Guyton, R L; Hicks, D G; Kaufman, M I; MacGowan, B J; Montelongo, S; Ng, E W; Robinson, R B; Tunnell, T W; Watts, P W; Zapata, P G

    2004-08-30

    The National Ignition Facility (NIF) requires diagnostics to analyze high-energy density physics experiments. A VISAR (Velocity Interferometry System for Any Reflector) diagnostic has been designed to measure shock velocities, shock breakout times, and shock emission of targets with sizes from 1 to 5 mm. An 8-inch-diameter fused silica triplet lens collects light at f/3 inside the 30-foot-diameter vacuum chamber. The optical relay sends the image out an equatorial port, through a 2-inch-thick vacuum window, and into two interferometers. A 60-kW VISAR probe laser operates at 659.5 nm with variable pulse width. Special coatings on the mirrors and cutoff filters are used to reject the NIF drive laser wavelengths and to pass a band of wavelengths for VISAR, passive shock breakout light, or thermal imaging light (bypassing the interferometers). The first triplet can be no closer than 500 mm from the target chamber center and is protected from debris by a blast window that is replaced after every event. The front end of the optical relay can be temporarily removed from the equatorial port, allowing other experimenters to use that port. A unique resolution pattern has been designed to validate the VISAR diagnostic before each use. All optical lenses are on kinematic mounts so that the pointing accuracy of the optical axis can be checked. Seven CCD cameras monitor the diagnostic alignment.

  7. Fielding of an Imaging VISAR Diagnostic at the National Ignition Facility (NIF)

    SciTech Connect

    Malone, R; Bower, J; Capelle, G; Celeste, J; Celliers, P; Frogget, B C; Guyton, R L; Kauffman, M; Lare, G; Lee, T; MacGowan, B; Montelongo, S; Thomas, T; Tunnell, T; Watts, P

    2004-06-30

    The National Ignition Facility (NIF) requires diagnostics to analyze high-energy density physics experiments. As a core NIF early light diagnostic, this system measures shock velocities, shock breakout times, and shock emission of targets with sizes from 1 to 5 mm. A 659.5 nm VISAR probe laser illuminates the target. An 8-inch-diameter fused silica triplet lens collects light at f/3 inside the 33-foot-diameter vacuum chamber. The optical relay sends the image out an equatorial port, through a 2-inch-thick vacuum window, and into two VISAR (Velocity Interferometer System for Any Reflector) interferometers. Both streak cameras and CCD cameras record the images. Total track is 75 feet. The front end of the optical relay can be temporarily removed from the equatorial port, allowing for other experimenters to use that port. The first triplet can be no closer than 500 mm from the target chamber center and is protected from debris by a blast window that is replaced after every event. Along with special coatings on the mirrors, cutoff filters reject the NIF drive laser wavelengths and pass a band of wavelengths for VISAR, for passive shock breakout light, or for thermal imaging light (bypassing the interferometers). Finite Element Analysis was performed on all mounting structures. All optical lenses are on kinematic mounts, so that the pointing accuracy of the optical axis can be checked. A two-color laser alignment scheme is discussed.

  8. Imaging VISAR diagnostic for the National Ignition Facility (NIF)

    NASA Astrophysics Data System (ADS)

    Malone, Robert M.; Bower, John R.; Bradley, David K.; Capelle, Gene A.; Celeste, John R.; Celliers, Peter M.; Collins, Gilbert W.; Eckart, Mark J.; Eggert, Jon H.; Frogget, Brent C.; Guyton, Robert L.; Hicks, Damien G.; Kaufman, Morris I.; MacGowan, Brian J.; Montelongo, Samuel; Ng, Edmund W.; Robinson, Ronald B.; Tunnell, Thomas W.; Watts, Phillip W.; Zapata, Paul G.

    2005-03-01

    The National Ignition Facility (NIF) requires diagnostics to analyze high-energy density physics experiments. A VISAR (Velocity Interferometry System for Any Reflector) diagnostic has been designed to measure shock velocities, shock breakout times, and shock emission of targets with sizes from 1 to 5 mm. An 8-inch-diameter fused silica triplet lens collects light at f/3 inside the 30-foot-diameter vacuum chamber. The optical relay sends the image out an equatorial port, through a 2-inch-thick vacuum window, and into two interferometers. A 60-kW VISAR probe laser operates at 659.5 nm with variable pulse width. Special coatings on the mirrors and cutoff filters are used to reject the NIF drive laser wavelengths and to pass a band of wavelengths for VISAR, passive shock breakout light, or thermal imaging light (bypassing the interferometers). The first triplet can be no closer than 500 mm from the target chamber center and is protected from debris by a blast window that is replaced after every event. The front end of the optical relay can be temporarily removed from the equatorial port, allowing other experimenters to use that port. A unique resolution pattern has been designed to validate the VISAR diagnostic before each use. All optical lenses are on kinematic mounts so that the pointing accuracy of the optical axis can be checked. Seven CCD cameras monitor the diagnostic alignment.

  9. Fielding of an imaging VISAR diagnostic at the National Ignition Facility (NIF)

    NASA Astrophysics Data System (ADS)

    Malone, Robert M.; Bower, John R.; Capelle, Gene A.; Celeste, John R.; Celliers, Peter M.; Frogget, Brent C.; Guyton, Robert L.; Kaufman, Morris I.; Lare, Gregory A.; Lee, Tony L.; MacGowan, Brian J.; Montelongo, Samuel; Ng, Edmund W.; Thomas, Thayne L., Jr.; Tunnell, Thomas W.; Watts, Phillip W.

    2004-10-01

    The National Ignition Facility (NIF) requires diagnostics to analyze high-energy density physics experiments. As a core NIF early light diagnostic, this system measures shock velocities, shock breakout times, and shock emission of targets with sizes from 1 to 5 mm. A 659.5 nm VISAR probe laser illuminates the target. An 8-inch-diameter fused silica triplet lens collects light at f/3 inside the 33-foot-diameter vacuum chamber. The optical relay sends the image out an equatorial port, through a 2-inch-thick vacuum window, and into two VISAR (Velocity Interferometer System for Any Reflector) interferometers. Both streak cameras and CCD cameras record the images. Total track is 75 feet. The front end of the optical relay can be temporarily removed from the equatorial port, allowing for other experimenters to use that port. The first triplet can be no closer than 500 mm from the target chamber center and is protected from debris by a blast window that is replaced after every event. Along with special coatings on the mirrors, cutoff filters reject the NIF drive laser wavelengths and pass a band of wavelengths for VISAR, for passive shock breakout light, or for thermal imaging light (bypassing the interferometers). Finite Element Analysis was performed on all mounting structures. All optical lenses are on kinematic mounts, so that the pointing accuracy of the optical axis can be checked. A two-color laser alignment scheme is discussed.

  10. Silica heat shield sizing

    NASA Technical Reports Server (NTRS)

    Ebbesmeyer, L. H.; Christensen, H. E.

    1975-01-01

    The sensitivity of silica heat shield requirements to gap width, tile edge radius, and heat transfer distribution within tile gaps was investigated. A two-dimensional thermal model was modified and used to determine the effect of two dimensional heat transfer distributions at high temperature reusable surface insulation edges on shuttle thermal protection system (TPS) requirements. The sensitivity of TPS requirements to coating thickness, emissivity, substructure thickness, and changes in gap heating for several locations on shuttle was also studied. An inverse solution technique was applied to temperature data obtained in the Ames 20 MW turbulent duct in order to examine the effect of tile edge radius on TPS requirements. The derived heating values were then used to predict TPS requirements. Results show that increasing tile radius reduces TPS requirements.

  11. 30 CFR 57.12037 - Fuses in high-potential circuits.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Fuses in high-potential circuits. 57.12037... Electricity Surface and Underground § 57.12037 Fuses in high-potential circuits. Fuse tongs or hotline tools, shall be used when fuses are removed or replaced in high-potential circuits....

  12. Silica/Polymer and Silica/Polymer/Fiber Composite Aerogels

    NASA Technical Reports Server (NTRS)

    Ou, Danny; Stepanian, Christopher J.; Hu, Xiangjun

    2010-01-01

    Aerogels that consist, variously, of neat silica/polymer alloys and silica/polymer alloy matrices reinforced with fibers have been developed as materials for flexible thermal-insulation blankets. In comparison with prior aerogel blankets, these aerogel blankets are more durable and less dusty. These blankets are also better able to resist and recover from compression . an important advantage in that maintenance of thickness is essential to maintenance of high thermal-insulation performance. These blankets are especially suitable as core materials for vacuum- insulated panels and vacuum-insulated boxes of advanced, nearly seamless design. (Inasmuch as heat leakage at seams is much greater than heat leakage elsewhere through such structures, advanced designs for high insulation performance should provide for minimization of the sizes and numbers of seams.) A silica/polymer aerogel of the present type could be characterized, somewhat more precisely, as consisting of multiply bonded, linear polymer reinforcements within a silica aerogel matrix. Thus far, several different polymethacrylates (PMAs) have been incorporated into aerogel networks to increase resistance to crushing and to improve other mechanical properties while minimally affecting thermal conductivity and density. The polymethacrylate phases are strongly linked into the silica aerogel networks in these materials. Unlike in other organic/inorganic blended aerogels, the inorganic and organic phases are chemically bonded to each other, by both covalent and hydrogen bonds. In the process for making a silica/polymer alloy aerogel, the covalent bonds are introduced by prepolymerization of the methacrylate monomer with trimethoxysilylpropylmethacrylate, which serves as a phase cross-linker in that it contains both organic and inorganic monomer functional groups and hence acts as a connector between the organic and inorganic phases. Hydrogen bonds are formed between the silanol groups of the inorganic phase and the

  13. Electric fuses operation, a review: 1. Pre-arcing period

    NASA Astrophysics Data System (ADS)

    Bussière, W.

    2012-02-01

    Electrical needs are continously growing because of many various factors linked to increasing consumption and a green perception. This development - geographical, increasing production, growth of transport network, interconnection of continental networks, diversity of the transport technologies ... - can not be dissociated from electrical safety considerations whatever the voltage level. For the three main levels of electric network - High Voltage, Middle Voltage and Low Voltage - one has to provide efficient electrical safety techniques or schemas which integrate different electrical safety apparatus. Among well-known apparatus we can cite SF6 breakers, HV and MV switchgears (such as MV cells, MV and LV high current vacuum switchgears), and fuses. Electrical fuses are especially used in the MV and LV domains, sometimes as an additional safety device and sometimes as the main electrical safety component which is linked to the electrical current breaking function of electric fuse. In the paper, we will quickly depict the various kinds of electric fuses. We will especially focuss on the physical mechanisms - whatever the type of work, experimental, theoretical, modelling or empirical - prevailing during the pre-arcing period of the electric fuse operation.

  14. Consistency results for the ROC curves of fused classifiers

    NASA Astrophysics Data System (ADS)

    Bjerkaas, Kristopher S.; Oxley, Mark E.; Bauer, Kenneth W., Jr.

    2004-08-01

    The U.S. Air Force is researching the fusion of multiple sensors and classifiers. Given a finite collection of classifiers to be fused one seeks a new classifier with improved performance. An established performance quantifier is the Receiver Operating Characteristic (ROC) curve. This curve allows one to view the probability of detection versus probability of false alarm in one graph. In reality only finite data is available so only an approximate ROC curve can be constructed. Previous research shows that one does not have to perform an experiment for this new fused classifier to determine its ROC curve. If the ROC curve for each individual classifier has been determined, then formulas for the ROC curve of the fused classifier exist for certain fusion rules. This will be an enormous saving in time and money since the performance of many fused classifiers will be determined without having to perform tests on each one. But, again, these will be approximate ROC curves, since they are based on finite data. We show that if the individual approximate ROC curves are consistent then the approximate ROC curve for the fused classifier is also consistent under certain circumstances. We give the details for these circumstances, as well as some examples related to sensor fusion.

  15. Bilateral maxillary fused second and third molars: a rare occurrence

    PubMed Central

    Liang, Rui-Zhen; Wu, Jin-Tao; Wu, You-Nong; Smales, Roger J; Hu, Ming; Yu, Jin-Hua; Zhang, Guang-Dong

    2012-01-01

    This case report describes the diagnosis and endodontic therapy of maxillary fused second and third molars, using cone-beam computed tomography (CBCT). A 31-year-old Chinese male, with no contributory medical or family/social history, presented with throbbing pain in the maxillary right molar area following an unsuccessful attempted tooth extraction. Clinical examination revealed what appeared initially to be a damaged large extra cusp on the buccal aspect of the distobuccal cusp of the second molar. However, CBCT revealed that a third molar was fused to the second molar. Unexpectedly, the maxillary left third molar also was fused to the second molar, and the crown of an unerupted supernumerary fourth molar was possibly also fused to the apical root region of the second molar. Operative procedures should not be attempted without adequate radiographic investigation. CBCT allowed the precise location of the root canals of the right maxillary fused molar teeth to permit successful endodontic therapy, confirmed after 6 months. PMID:23222992

  16. Silica-supported biomimetic membranes.

    PubMed

    Ariga, Katsuhiko

    2004-01-01

    The hybridization of lipid membranes with inorganic silica-based framework results in mechanically stable biomembrane mimics. This account describes three types of silica-based biomimetic membranes. As the first example, a Langmuir monolayer of dialkylalkoxysilane was polymerized and immobilized onto a porous glass plate. Permeability through the monolayer-immobilized glass was regulated by phase transition of the immobilized monolayer. In the second example, spherical vesicles covalently attached to a silica cover layer (Cerasome) were prepared. The Cerasome was stable enough to be assembled into layer-by-layer films without destruction of its vesicular structure. This material could be an example of the multicellular assembly. Mesoporous silica films densely filling peptide assemblies (Proteosilica) are introduced as the third example. The Proteosilica was synthesized as a transparent film through template sol-gel reaction using amphiphilic peptides.

  17. Modulating Paratropicity Strength in Diareno-Fused Antiaromatics.

    PubMed

    Frederickson, Conerd K; Zakharov, Lev N; Haley, Michael M

    2016-12-28

    Understanding and controlling the electronic structure of molecules is crucial when designing and optimizing new organic semiconductor materials. We report the regioselective synthesis of eight π-expanded diarenoindacene analogues based on the indeno[1,2-b]fluorene framework along with the computational investigation of an array of diareno-fused antiaromatic compounds possessing s-indacene, pentalene, or cyclobutadiene cores. Analysis of the experimental and computationally derived optoelectronic properties uncovered a linear correlation between the bond order of the fused arene bond and the paratropicity strength of the antiaromatic unit. The Ered(1) for the pentalene and indacene core molecules correlates well with their calculated NICSπZZ values. The findings of this study can be used to predict the properties of, and thus rationally design, new diareno-fused antiaromatic molecules for use as organic semiconductors.

  18. Ferrocene-fused derivatives of acenes, tropones and thiepins

    NASA Astrophysics Data System (ADS)

    Maharjan, Bidhya Laxmi

    This research project is concentrated on tuning the properties of small organic molecules, namely polyacenes, tropones and thiepins, by incorporating redox-active transition metal centers pi-bonded to terminal cyclopentadienyl ligands. Organometallicfused acenequinones, tropones, thiepins and cyclopentadiene-capped polyacenes were synthesized and characterized. This work was divided into three parts: first, the synthesis of ferrocene-fused acenequinones, cyclopentadiene-capped acenequinones and their subsequent aromatization to polyacenes; second, the synthesis of ferrocene-fused tropones, thiotropones and tropone oxime; and third, the synthesis of ferrocene-fused thiepins. Ferrocene-fused quinones are the precursors to our target complexes. Our synthetic route to ferrocenequinones involved two-fold aldol condensation between 1,2- diformylferrocene and naphthalene-1,4-diol or anthracene-1,4-diol, and four-fold condensation between 1,2-diformylferrocene and 1,4-cyclohexanedione. Reduction of ferrocene-fused quinones with borane in THF resulted in ferrocene-fused dihydroacenes. Attempts to reduce ferrocene-fused acenequinones with sodium dithionite led to metalfree cyclopentadiene- (Cp-) capped acenequinones. Cp-capped acenequinones were aromatized to bis(triisopropylsilyl)ethynyl polyacenes by using lithium (triisopropylsilyl)acetylide (TIPSC≡CLi) with subsequent dehydroxylation by stannous chloride. The compounds were characterized by using spectroscopic methods and X-ray crystallography. Further, the electronic properties of these compounds were studied by using cyclic voltammetry and UV-visible spectroscopy. Cyclic voltammetry showed oxidation potentials of Cp-capped TIPS-tetracene and bis-Cp-capped TIPS-anthracene as 0.49 V and 0.61 V, respectively (vs. ferrocene/ferrocenium). The electrochemical band gaps were 2.15 eV and 2.58 eV, respectively. Organic thin-film transistor device performance of Cp-capped polyacenes was studied using solution deposition

  19. Interdisciplinary Treatment of a Fused Lower Premolar with Supernumerary Tooth

    PubMed Central

    Gadimli, Cengiz; Sari, Zafer

    2011-01-01

    The objective of this report is to describe combined orthodontic and endodontic treatment of a fused mandibular premolar with supernumerary tooth. The patient was a 15 year old girl seeking orthodontic treatment for the correction of maxillary and mandibular crowding. Cephalometric examination revealed skeletally Class I relationship. The panoramic radiograph showed a fused tooth with two separate pulp chambers and two separate root canals connecting in apical third. After the endodontic treatment of the fused teeth, the stripping of the supernumerary tooth was performed to establish a Class I canine relationship and to correct midline deviation. At the end of the treatment, the crowding was resolved and positive overjet and overbite was achieved. PMID:21769280

  20. Micromachined contact fuses for earth penetrator applications. LDRD final report

    SciTech Connect

    Davies, B.R.; Montague, S.; Smith, J.H.; Rimkus, V.C.

    1998-01-01

    MEMS is an enabling technology that may provide low-cost devices capable of sensing motion in a reliable and accurate manner. This paper describes preliminary work in MEMS contact fuse development at Sandia National Laboratories. This work leverages a process for integrating both the micromechanical structures and microelectronics circuitry of a MEMS devices on the same chip. The design and test results of an integrated MEMS high-g accelerometer will be detailed. This design could be readily modified to create a high-g switching device suitable for a contact fuse. A potential design for a low-g acceleration measurement device (suitable for such fusing operations as path length measurement device of both whole path length or safe separation distance) for artillery rounds and earth penetrator devices will also be discussed in this document (where 1 g {approx} 9.81 m/s{sup 2}).

  1. On Fusing Recursive Traversals of K-d Trees

    SciTech Connect

    Rajbhandari, Samyam; Kim, Jinsung; Krishnamoorthy, Sriram; Pouchet, Louis-Noel; Rastello, Fabrice; Harrison, Robert J.; Sadayappan, Ponnuswamy

    2016-03-17

    Loop fusion is a key program transformation for data locality optimization that is implemented in production compilers. But optimizing compilers currently cannot exploit fusion opportunities across a set of recursive tree traversal computations with producer-consumer relationships. In this paper, we develop a compile-time approach to dependence characterization and program transformation to enable fusion across recursively specified traversals over k-ary trees. We present the FuseT source-to-source code transformation framework to automatically generate fused composite recursive operators from an input program containing a sequence of primitive recursive operators. We use our framework to implement fused operators for MADNESS, Multiresolution Adaptive Numerical Environment for Scientific Simulation. We show that locality optimization through fusion can offer more than an order of magnitude performance improvement.

  2. Push-pull enamines in the synthesis of fused azaheterocycles

    NASA Astrophysics Data System (ADS)

    Dar'in, D. V.; Lobanov, P. S.

    2015-06-01

    The review summarizes published data on the methods of the synthesis of fused nitrogen-containing heterocycles via push-pull enamines (mainly enaminones). Both intermolecular (cyclocondensations) and intramolecular (cyclizations) transformations of enamines, in which both nucleophilic centres of enamine (carbon and nitrogen) are incorporated into the resulting heterocycle, are considered. The data on the reactivity of enamines cover a broad range of facile methods for the preparation of diverse fused pyridines (quinolines, isoquinolines, pyridopyridines, etc.) and pyrroles (indoles, tetrahydrocarbazoles, pyrrolopyridines, etc.). The bibliography includes 191 references.

  3. Heating and Burning of Optical Fibers and Cables by Light Scattered from Bubble Train Formed by Optical Fiber Fuse

    NASA Astrophysics Data System (ADS)

    Yamada, Makoto; Tomoe, Akisumi; Kinoshita, Takahiro; Koyama, Osanori; Katuyama, Yutaka; Shibuya, Takashi

    We investigate in detail the scattering properties and heating characteristics in various commercially available optical fibers and fiber cables when a bubble train forms in the middle of the fiber as a result of the fiber fuse phenomenon that occurs when a high power signal is launched into the fiber. We found theoretically and experimentally that almost all the optical light is scattered at the top of the bubble train. The scattered light heats UV coated fiber, nylon jacketed silica fiber, fire-retardant jacketed fiber (PVC or FRPE jacketed fiber) and fire-retardant fiber cable (PVC or FRPE fiber cable), to around 100, over 200 and over 600°C, respectively, and finally the fiber burns and is destroyed at a launched optical power of 3W. Furthermore, it is confirmed that the combustion does not spread when we use fire retardant jacketed fibers.

  4. Bio-inspired Silicification of Silica-binding Peptide-Silk Protein Chimeras: Comparison of Chemically and Genetically Produced Proteins

    PubMed Central

    Canabady-Rochelle, Laetitia L.S.; Belton, David J.; Deschaume, Olivier; Currie, Heather A.; Kaplan, David L.; Perry, Carole C.

    2012-01-01

    Novel protein chimeras constituted of ‘silk’ and a silica-binding peptide (KSLSRHDHIHHH) were synthesized by genetic or chemical approaches and their influence on silica-silk based chimera composite formation evaluated. Genetic chimeras were constructed from 6 or 15 repeats of the 32 amino acid consensus sequence of Nephila clavipes spider silk ([SGRGGLGGQG AGAAAAAGGA GQGGYGGLGSQG]n) to which one silica binding peptide was fused at the N terminus. For the chemical chimera, 25 equivalents of the silica binding peptide were chemically coupled to natural Bombyx mori silk after modification of tyrosine groups by diazonium coupling and EDC/NHS activation of all acid groups. After silica formation under mild, biomaterial compatible conditions the effect of peptide addition on the properties of the silk and chimeric silk-silica composite materials was explored. The composite biomaterial properties could be related to the extent of silica condensation and to the higher number of silica binding sites in the chemical chimera as compared to the genetically derived variants. In all cases, the structure of the protein / chimera in solution dictated the type of composite structure that formed with the silica deposition process having little effect on the secondary structural composition of the silk based materials. Similarly to our study of genetic silk based chimeras containing the R5 peptide (SSKKSGSYSGSKGSKRRIL), the role of the chimeras (genetic and chemical) used in the present study resided more in aggregation and scaffolding than in the catalysis of condensation. The variables of peptide identity, silk construct (number of consensus repeats or silk source) and approach to synthesis (genetic or chemical) can be used to ‘tune’ the properties of the composite materials formed and is a general approach which can be used to prepare a range of materials for biomedical and sensor based applications. PMID:22229696

  5. Graft linker immobilization for spatial control of protein immobilization inside fused microchips.

    PubMed

    Shirai, Kentaro; Renberg, Björn; Sato, Kae; Mawatari, Kazuma; Konno, Tomohiro; Ishihara, Kazuhiko; Kitamori, Takehiko

    2009-12-01

    Fused silica glass microchips have several attractive features for lab-on-a-chip applications; they can be machined with excellent precision down to nanospace; are stable; transparent and can be modified with a range of silanization agents to change channel surface properties. For immobilization, however, ligands must be added after bonding, since the harsh bonding conditions using heat or hydrofluoric acid would remove all prior immobilized ligands. For spatial control over immobilization, UV-mediated immobilization offers several advantages; spots can be created in parallel, the feature size can be made small, and spatial control over patterns and positions is excellent. However, UV sensitive groups are often based on hydrophobic chemical moieties, which unfortunately result in greater non-specific binding of biomolecules, especially proteins. Here, we present techniques in which any -CH(x) (x=1,2,3) containing surface coating can be used as foundation for grafting a hydrophilic linker with a chemical anchor, a carboxyl group, to which proteins and amine containing molecules can be covalently coupled. Hence, the attractive features of many well-known protein and biomolecule repelling polymer coatings can be utilized while achieving site-specific immobilization only to pre-determined areas within the bonded microchips.

  6. Analysis of silica fume produced by zircon desilication.

    PubMed

    Phillips, D N; Carter, J

    2003-07-27

    Novel chemical methods have been developed to allow for the determination of the components of silica fume produced by zircon desilication. Hitherto, no methods have been described for the analysis of this material. The amorphous silica is first removed by treatment with sodium hydroxide. The residue from the hydroxide treatment may then be subjected to a suite of reagents to determine the zircon, the total zirconia, the monoclinic zirconia and the tetragonal zirconia content of the fume. The zircon content of the fume is determined by treatment of the hydroxide residue with concentrated hydrofluoric acid (HF). The total zirconia content of the fume is determined by digestion of the hydroxide residue with fuming sulphuric acid (oleum), while the relative amounts of monoclinic and tetragonal zirconia may be found by treatment of the hydroxide residue with 10%w/v HF, which attacks the less stable tetragonal phase. Both X-ray diffraction and particle size analysis were used to validate the steps in the analytical procedure. An explanation of the presence of tetragonal zirconia in the fume is proposed. A greater understanding of the composition of the fume led to the installation of a separator in the company's production line to remove the zircon. Australian Fused Materials (AFM) now produces a vastly superior grade of fume marketed under the code SF-98.

  7. Contamination-resistant silica antireflective coating with closed ordered mesopores.

    PubMed

    Sun, Jinghua; Zhang, Qinghua; Ding, Ruimin; Lv, Haibing; Yan, Hongwei; Yuan, Xiaodong; Xu, Yao

    2014-08-21

    Porous silica optical antireflective (AR) coatings prepared by traditional sol-gel method have been extensively used for high power laser systems, but a serious drawback is that contamination existing in the high vacuum is easily absorbed by the disordered open pore structure, resulting in a fast decrease in transmittance. To improve the stability of transmittance in vacuum, a contamination-resistant silica AR coating with ordered mesopores completely closed by hydrophobic-oleophobic groups was successfully developed on a fused quartz substrate. The ordered mesopores in the coating were controlled under the direction of surfactant F127 via an evaporation-induced-self-assembling process and then were closed by post-grafting long chain fluoroalkylsilane. The grazing incidence small angle X-ray scattering (GISAXS) and the X-ray reflectivity (XRR) results indicated that the mesopores in the coating constructed a Fmmm orthorhombic symmetry structure with a (010) plane parallel to the substrate. Cage-like mesopores were confirmed by nitrogen adsorption-desorption analysis. The obtained coatings showed low surface roughness, excellent abrase-resistance and high transmittance of 100% on quartz substrate. Especially, the decrease of transmittance tested with polydimethylsiloxane pollution in vacuum within one-month was as small as 0.02%. The laser induced damage threshold was up to 59.8 J cm(-2) at a 12 ns laser pulse of 1053 nm wavelength. This work provides an alternative way to fabricate AR coatings with high stability.

  8. Mechanically Tunable Hollow Silica Ultrathin Nanoshells for Ultrasound Contrast Agents

    PubMed Central

    Liberman, A.; Wang, J.; Lu, N.; Viveros, R.D.; Allen, C. A.; Mattrey, R.F.; Blair, S.L.; Trogler, W.C.; Kim, M. J.; Kummel, A.C.

    2015-01-01

    Perfluoropentane (PFP) gas filled biodegradable iron-doped silica nanoshells have been demonstrated as long-lived ultrasound contrast agents. Nanoshells are synthesized by a sol-gel process with tetramethyl orthosilicate (TMOS) and iron ethoxide. Substituting a fraction of the TMOS with R-substituted trialkoxysilanes produces ultrathin nanoshells with varying shell thicknesses and morphologies composed of fused nanoflakes. The ultrathin nanoshells had continuous ultrasound Doppler imaging lifetimes exceeding 3 hours, were twice as bright using contrast specific imaging, and had decreased pressure thresholds compared to control nanoshells synthesized with just TMOS. Transmission electron microscopy (TEM) showed that the R-group substituted trialkoxysilanes could reduce the mechanically critical nanoshell layer to 1.4 nm. These ultrathin nanoshells have the mechanical behavior of weakly linked nanoflakes but the chemical stability of silica. The synthesis can be adapted for general fabrication of three-dimensional nanostructures composed of nanoflakes, which have thicknesses from 1.4–3.8 nm and diameters from 2–23 nm. PMID:26955300

  9. Mechanically Tunable Hollow Silica Ultrathin Nanoshells for Ultrasound Contrast Agents.

    PubMed

    Liberman, A; Wang, J; Lu, N; Viveros, R D; Allen, C A; Mattrey, R F; Blair, S L; Trogler, W C; Kim, M J; Kummel, A C

    2015-07-08

    Perfluoropentane (PFP) gas filled biodegradable iron-doped silica nanoshells have been demonstrated as long-lived ultrasound contrast agents. Nanoshells are synthesized by a sol-gel process with tetramethyl orthosilicate (TMOS) and iron ethoxide. Substituting a fraction of the TMOS with R-substituted trialkoxysilanes produces ultrathin nanoshells with varying shell thicknesses and morphologies composed of fused nanoflakes. The ultrathin nanoshells had continuous ultrasound Doppler imaging lifetimes exceeding 3 hours, were twice as bright using contrast specific imaging, and had decreased pressure thresholds compared to control nanoshells synthesized with just TMOS. Transmission electron microscopy (TEM) showed that the R-group substituted trialkoxysilanes could reduce the mechanically critical nanoshell layer to 1.4 nm. These ultrathin nanoshells have the mechanical behavior of weakly linked nanoflakes but the chemical stability of silica. The synthesis can be adapted for general fabrication of three-dimensional nanostructures composed of nanoflakes, which have thicknesses from 1.4-3.8 nm and diameters from 2-23 nm.

  10. Mechanical Stability of Templated Mesoporous Silica Thin Films

    SciTech Connect

    Williford, Rick E.; Li, Xiaohong S.; Addleman, Raymond S.; Fryxell, Glen E.; Baskaran, Suresh; Birnbaum, Jerome C.; Coyle, Christopher A.; Zemanian, Thomas S.; Wang, Chong M.; Courtney, Andrea R.

    2005-11-07

    Mesoporous silica thin films about 1 micron thick were prepared by spin casting using several organic templates that provide a range of pore structures from disordered (sponge-like) to more ordered (honeycomb-like) 2D hexagonal arrays. Nanoindentation measurements indicate that the elastic modulus (E), and thus the density, of the pore wall material are substantially lower than for fused silica. The corresponding lower dielectric constant for pore walls was used to calculate film porosities (P) with recent correlations from the literature. Curve fits to the standard modulus vs. porosity correlation, E/Eporewall=(1-P)n, for the films gave lower n=2.2 for the honeycomb-like film with higher E, but higher n=2.5 for the sponge-like film with lower E, in contrast to theoretical expectations (n=2 for sponge-like and n=3 for honeycomb-like). Although the dielectric constant depends primarily on first-order structural information (P), the elastic modulus of these structurally imperfect films required second-order (pore wall thickness/diameter ratio) and third-order (pore connectivity) parameters to resolve the data. The power law exponent n can vary continuously, depending on the details of the mesostructure, and should not be assumed a' priori unless justified by detailed structural information

  11. 29 CFR 1926.907 - Use of safety fuse.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 8 2010-07-01 2010-07-01 false Use of safety fuse. 1926.907 Section 1926.907 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Blasting and the Use of Explosives § 1926.907...

  12. 59. VIEW OF FUSES AND A CURRENT TRANSFORMER LOCATED IN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    59. VIEW OF FUSES AND A CURRENT TRANSFORMER LOCATED IN THE SIGNAL POWER CONDITIONING ROOM. THE CURRENT TRANSFORMER (UPPER RIGHT) IS AN INDUCTION COUPLED SENSOR WHICH IS USED TO REDUCE HIGH CURRENT TO ANALOGOUS LOW VALUES SAFE TO USE IN CONTROL ROOM CIRCUITRY. - New York, New Haven & Hartford Railroad, Cos Cob Power Plant, Sound Shore Drive, Greenwich, Fairfield County, CT

  13. Fused-Ring Oxazolopyrrolopyridopyrimidine Systems with Gram-Negative Activity

    PubMed Central

    Chen, Yiyuan; Moloney, Jonathan G.; Christensen, Kirsten E.; Moloney, Mark G.

    2017-01-01

    Fused polyheterocyclic derivatives are available by annulation of a tetramate scaffold, and been shown to have antibacterial activity against a Gram-negative, but not a Gram-positive, bacterial strain. While the activity is not potent, these systems are structurally novel showing, in particular, a high level of polarity, and offer potential for the optimization of antibacterial activity. PMID:28098784

  14. The burning fuse model of unbecoming in time

    NASA Astrophysics Data System (ADS)

    Norton, John D.

    2015-11-01

    In the burning fuse model of unbecoming in time, the future is real and the past is unreal. It is used to motivate the idea that there is something unbecoming in the present literature on the metaphysics of time: its focus is merely the assigning of a label "real."

  15. Crossed fused renal ectopia: Challenges in diagnosis and management

    PubMed Central

    Solanki, Shailesh; Bhatnagar, Veereshwar; Gupta, Arun K.; Kumar, Rakesh

    2013-01-01

    Aim: Crossed fused renal ectopia is a rare congenital malformation, which is reported to be usually asymptomatic but may have varied presentations. This survey was conducted to study the clinical profile and the challenges posed in the management of this entity. Materials and Methods: Retrospective analysis of 6 patients diagnosed to have crossed fused renal ectopia during 1997-2010. The diagnosis was confirmed during surgical exploration in one patient. In one patient it was detected on antenatal ultrasonography and in the other 4 patients it was detected during investigations for abdominal pain, abdominal mass, anorectal malformation and urinary tract infection. Results: The left moiety was crossed and fused with the right moiety in 4 cases. Ultrasonography was found to be a good screening investigation with useful diagnostic contributions from CT scans, radionuclide scintigraphy and magnetic resonance urography. Micturating cystourethrography revealed presence of VUR in 4 cases, 3 of whom have undergone ureteric reimplantation. Two patients required pyeloplasty for pelviureteric junction obstruction; in one of these patients the upper ureter was entrapped in the isthmus. In one patient, a non-functioning moiety resulted in nephrectomy. All children were asymptomatic at last follow-up with stable renal functions. Conclusions: Crossed fused renal ectopia was detected in most patients during investigation for other problems. It was found more commonly in boys. The left moiety was crossed to the right in the majority of cases. Associated urological problems were found in most cases and required the appropriate surgical management. PMID:23599575

  16. 40. Main fuses and knife switch for power to the ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    40. Main fuses and knife switch for power to the bridge, located in the control house. This is one of two located at either end of the main electrical panel (photograph 41). Facing east. - Henry Ford Bridge, Spanning Cerritos Channel, Los Angeles-Long Beach Harbor, Los Angeles, Los Angeles County, CA

  17. Improved synthesis of 3-aryl isoxazoles containing fused aromatic rings

    PubMed Central

    Mirzaei, Yousef R.; Weaver, Matthew J.; Steiger, Scott A.; Kearns, Alison K.; Gajewski, Mariusz P.; Rider, Kevin C.; Beall, Howard D.; Natale, N.R.

    2012-01-01

    A critical comparison of methods to prepare sterically hindered 3-aryl isoxazoles containing fused aromatic rings using the nitrile oxide cycloaddition (NOC) reveal that modification of the method of Bode, Hachisu, Matsuura, and Suzuki (BHMS), utilizing either triethylamine as base or sodium enolates of the diketone, ketoester, and ketoamide dipolarophiles, respectively, was the method of choice for this transformation. PMID:23526841

  18. Non-invasive management of fused upper incisors.

    PubMed

    Samimi, Pouran; Shirban, Mohammad-Reza; Arbabzadeh-Zavareh, Farahnaz

    2012-01-01

    The union of two different dental sprouts which can happen in any phase of dental development is commonly called fusion. This developmental anomaly may cause clinical problems including esthetic impairment, which are mainly treated by endodontic and surgical treatments. There are a few reports of conservative not invasive treatment of fused incisors teeth through restorative or prosthetic techniques. They are rarely reported in mandibular posterior teeth. This paper presents an unusual case of fusion of 7 and 8, and also 9 and 10 teeth which was treated with a nonendodontic and nonsurgical conservative approach. Patient was a healthy18-year-old female with chief complaint of bad-looking teeth that in intraoral examination revealed the fusion of 7 and 8, and also 9 and 10 teeth. The space between the mesial of the 6 and 11 teeth was reconstructed. Diastema between the fused teeth was closed. A new lateral tooth was replaced between the fused teeth (7 and 8) and 6 tooth with direct fiber-reinforced composite. The space between the fused teeth (9 and 10) and also tooth 11 was partially closed. Gingival papillas were reconstructed using pink composite. The mandibular anterior missing teeth were replaced with rochett bridge. At the end of treatment the esthetic of the patient was improved. As the treatment was not invasive, major complications are not expected; however, there is potential for eventual long-term periodontal problems due to poor oral hygiene. Debonding of the rochett bridge may happen as well.

  19. Non-invasive management of fused upper incisors

    PubMed Central

    Samimi, Pouran; Shirban, Mohammad-Reza; Arbabzadeh-Zavareh, Farahnaz

    2012-01-01

    The union of two different dental sprouts which can happen in any phase of dental development is commonly called fusion. This developmental anomaly may cause clinical problems including esthetic impairment, which are mainly treated by endodontic and surgical treatments. There are a few reports of conservative not invasive treatment of fused incisors teeth through restorative or prosthetic techniques. They are rarely reported in mandibular posterior teeth. This paper presents an unusual case of fusion of 7 and 8, and also 9 and 10 teeth which was treated with a nonendodontic and nonsurgical conservative approach. Patient was a healthy18-year-old female with chief complaint of bad-looking teeth that in intraoral examination revealed the fusion of 7 and 8, and also 9 and 10 teeth. The space between the mesial of the 6 and 11 teeth was reconstructed. Diastema between the fused teeth was closed. A new lateral tooth was replaced between the fused teeth (7 and 8) and 6 tooth with direct fiber-reinforced composite. The space between the fused teeth (9 and 10) and also tooth 11 was partially closed. Gingival papillas were reconstructed using pink composite. The mandibular anterior missing teeth were replaced with rochett bridge. At the end of treatment the esthetic of the patient was improved. As the treatment was not invasive, major complications are not expected; however, there is potential for eventual long-term periodontal problems due to poor oral hygiene. Debonding of the rochett bridge may happen as well. PMID:22363372

  20. 30 CFR 56.12036 - Fuse removal or replacement.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Fuse removal or replacement. 56.12036 Section 56.12036 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES...

  1. 30 CFR 56.12036 - Fuse removal or replacement.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Fuse removal or replacement. 56.12036 Section 56.12036 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES...

  2. 30 CFR 56.12036 - Fuse removal or replacement.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Fuse removal or replacement. 56.12036 Section 56.12036 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES...

  3. 30 CFR 56.12036 - Fuse removal or replacement.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Fuse removal or replacement. 56.12036 Section 56.12036 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES...

  4. 30 CFR 56.12036 - Fuse removal or replacement.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Fuse removal or replacement. 56.12036 Section 56.12036 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES...

  5. 30 CFR 18.52 - Renewal of fuses.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Renewal of fuses. 18.52 Section 18.52 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR TESTING, EVALUATION, AND APPROVAL OF MINING PRODUCTS ELECTRIC MOTOR-DRIVEN MINE EQUIPMENT AND ACCESSORIES Construction and Design...

  6. Combining a thermal-imaging diagnostic with an existing imaging VISAR diagnostic at the National Ignition Facility (NIF)

    SciTech Connect

    Robert M. Malone; John R. Celesteb; Peter M. Celliers; Brent C. Froggeta; Robert L. Guyton; Morris I. Kaufman; Tony L. Lee; Brian J. MacGowan; Edmund W. Ng; Imants P. Reinbachs; Ronald B. Robinson; Lynn G. Seppala; Tom W. Tunnell; Phillip W. Watts

    2005-01-01

    Optical diagnostics are currently being designed to analyze high-energy density physics experiments at the National Ignition Facility (NIF). Two independent line-imaging Velocity Interferometer System for Any Reflector (VISAR) interferometers have been fielded to measure shock velocities, breakout times, and emission of targets having sizes of 1–5 mm. An 8-inch-diameter, fused silica triplet lens collects light at f/3 inside the 30-foot-diameter NIF vacuum chamber. VISAR recordings use a 659.5-nm probe laser. By adding a specially coated beam splitter to the interferometer table, light at wavelengths from 540 to 645 nm is spilt into a thermal-imaging diagnostic. Because fused silica lenses are used in the first triplet relay, the intermediate image planes for different wavelengths separate by considerable distances. A corrector lens on the interferometer table reunites these separated wavelength planes to provide a good image. Thermal imaging collects light at f/5 from a 2-mm object placed at Target Chamber Center (TCC). Streak cameras perform VISAR and thermal-imaging recording. All optical lenses are on kinematic mounts so that pointing accuracy of the optical axis may be checked. Counter-propagating laser beams (orange and red) are used to align both diagnostics. The red alignment laser is selected to be at the 50 percent reflection point of the beam splitter. This alignment laser is introduced at the recording streak cameras for both diagnostics and passes through this special beam splitter on its way into the NIF vacuum chamber.

  7. Combining a thermal-imaging diagnostic with an existing imaging VISAR diagnostic at the National Ignition Facility (NIF)

    SciTech Connect

    Malone, R; Celeste, J; Celliers, P; Frogget, B; Guyton, R L; Kaufman, M; Lee, T; MacGowan, B; Ng, E W; Reinbachs, I P; Robinson, R B; Seppala, L; Tunnell, T W; Watts, P

    2005-07-07

    Optical diagnostics are currently being designed to analyze high-energy density physics experiments at the National Ignition Facility (NIF). Two independent line-imaging Velocity Interferometer System for Any Reflector (VISAR) interferometers have been fielded to measure shock velocities, breakout times, and emission of targets having sizes of 1-5 mm. An 8-inch-diameter, fused silica triplet lens collects light at f/3 inside the 30-foot-diameter NIF vacuum chamber. VISAR recordings use a 659.5-nm probe laser. By adding a specially coated beam splitter to the interferometer table, light at wavelengths from 540 to 645 nm is spilt into a thermal-imaging diagnostic. Because fused silica lenses are used in the first triplet relay, the intermediate image planes for different wavelengths separate by considerable distances. A corrector lens on the interferometer table reunites these separated wavelength planes to provide a good image. Thermal imaging collects light at f/5 from a 2-mm object placed at Target Chamber Center (TCC). Streak cameras perform VISAR and thermal-imaging recording. All optical lenses are on kinematic mounts so that pointing accuracy of the optical axis may be checked. Counter-propagating laser beams (orange and red) are used to align both diagnostics. The red alignment laser is selected to be at the 50 percent reflection point of the beam splitter. This alignment laser is introduced at the recording streak cameras for both diagnostics and passes through this special beam splitter on its way into the NIF vacuum chamber.

  8. Combining a thermal-imaging diagnostic with an existing imaging VISAR diagnostic at the National Ignition Facility (NIF)

    NASA Astrophysics Data System (ADS)

    Malone, Robert M.; Celeste, John R.; Celliers, Peter M.; Frogget, Brent C.; Guyton, Robert L.; Kaufman, Morris I.; Lee, Tony L.; MacGowan, Brian J.; Ng, Edmund W.; Reinbachs, Imants P.; Robinson, Ronald B.; Seppala, Lynn G.; Tunnell, Thomas W.; Watts, Phillip W.

    2005-08-01

    Optical diagnostics are currently being designed to analyze high-energy density physics experiments at the National Ignition Facility (NIF). Two independent line-imaging Velocity Interferometer System for Any Reflector (VISAR) interferometers have been fielded to measure shock velocities, breakout times, and emission of targets having sizes of 1-5 mm. An 8-inch-diameter, fused silica triplet lens collects light at f/3 inside the 30-foot-diameter NIF vacuum chamber. VISAR recordings use a 659.5-nm probe laser. By adding a specially coated beam splitter to the interferometer table, light at wavelengths from 540 to 645 nm is spilt into a thermal-imaging diagnostic. Because fused silica lenses are used in the first triplet relay, the intermediate image planes for different wavelengths separate by considerable distances. A corrector lens on the interferometer table reunites these separated wavelength planes to provide a good image. Thermal imaging collects light at f/5 from a 2-mm object placed at Target Chamber Center (TCC). Streak cameras perform VISAR and thermal-imaging recording. All optical lenses are on kinematic mounts so that pointing accuracy of the optical axis may be checked. Counter-propagating laser beams (orange and red) are used to align both diagnostics. The red alignment laser is selected to be at the 50 percent reflection point of the beam splitter. This alignment laser is introduced at the recording streak cameras for both diagnostics and passes through this special beam splitter on its way into the NIF vacuum chamber.

  9. METHOD OF SEPARATING FISSION PRODUCTS FROM FUSED BISMUTH-CONTAINING URANIUM

    DOEpatents

    Wiswall, R.H.

    1958-06-24

    A process is described for removing metal selectively from liquid metal compositions. The method effects separation of flssion product metals selectively from dilute solution in fused bismuth, which contains uraniunn in solution without removal of more than 1% of the uranium. The process comprises contacting the fused bismuth with a fused salt composition consisting of sodium, potassium and lithium chlorides, adding to fused bismuth and molten salt a quantity of bismuth chloride which is stoichiometrically required to convert the flssion product metals to be removed to their chlorides which are more stable in the fused salt than in the molten metal and are, therefore, preferentially taken up in the fused salt phase.

  10. Ultrafast laser photoinscription of polarization sensitive devices in bulk silica glass.

    PubMed

    Cheng, G; Mishchik, K; Mauclair, C; Audouard, E; Stoian, R

    2009-06-08

    Ultrashort pulsed laser irradiation of bulk fused silica may result under specific energetic conditions in the self-organization of subwavelength material redistribution regions within the laser trace. The modulated structures have birefringent properties and show unusual anisotropic light scattering and reflection characteristics. We report here on the formation of waveguiding structures with remarkable polarization effects for infrared light. The photoinscription process using 800 nm femtosecond laser pulses is accompanied by third harmonic generation and polarization dependent anisotropic scattering of UV photons. The photowritten structures can be arranged in three-dimensional patterns generating complex propagation and polarization effects due to the anisotropic optical properties.

  11. Fabrication of isolated platinum nanowire gratings and nanoparticles on silica substrate by femtosecond laser irradiation

    NASA Astrophysics Data System (ADS)

    Nakajima, Yasutaka; Nedyalkov, Nikolay; Takami, Akihiro; Terakawa, Mitsuhiro

    2017-02-01

    We demonstrate the fabrication of isolated platinum nanostructures on a silica substrate by using femtosecond laser. Nanowire gratings which have short periodicities of approximately 50 nm were formed by irradiating a platinum thin film deposited on a fused silica substrate with 800-nm wavelength femtosecond laser pulses. The structural evolution from the nanowire gratings to nanoparticles was observed only by increasing the number of pulses. The periodicities or diameters of the structures showed good uniformity. Scanning electron microscopy of the surfaces and theoretical calculation of temperature profile using a two-temperature model revealed that the structural evolution can be attributed to the fragmentation of the formed nanowires. The presented method provides a simple and high-throughput technique for fabricating both metal nanowire gratings and nanoparticles, which have the potential to be used for the fabrication of optical, electrical and biomedical devices.

  12. Investigation of the micro-mechanical properties of femtosecond laser-induced phases in amorphous silica

    NASA Astrophysics Data System (ADS)

    Athanasiou, Christos-Edward; Bellouard, Yves

    2016-03-01

    Femtosecond pulses used in the regime where self-organized patterns are found have two noticeable effects in amorphous silica's (a-SiO2) optical and chemical properties: The decrease of the material's refractive index as well as an enhanced etching selectivity. However, the effect on the material mechanical properties is unexplored. In this paper, we present elastic modulus measurements of fused silica exposed to femtosecond laser pulses in the regime where nanogratings are found. The measurement principle is based on the use of femtosecond laser fabricated displacement amplification mechanism combined with a discrete stiffness model. In this laser exposure regime, a significant decrease of the elastic modulus is observed. Our findings are consistent with the existence of a porous structure found within nanogratings lamellas.

  13. Living bacteria in silica gels

    NASA Astrophysics Data System (ADS)

    Nassif, Nadine; Bouvet, Odile; Noelle Rager, Marie; Roux, Cécile; Coradin, Thibaud; Livage, Jacques

    2002-09-01

    The encapsulation of enzymes within silica gels has been extensively studied during the past decade for the design of biosensors and bioreactors. Yeast spores and bacteria have also been recently immobilized within silica gels where they retain their enzymatic activity, but the problem of the long-term viability of whole cells in an inorganic matrix has never been fully addressed. It is a real challenge for the development of sol-gel processes. Generic tests have been performed to check the viability of Escherichia coli bacteria in silica gels. Surprisingly, more bacteria remain culturable in the gel than in an aqueous suspension. The metabolic activity of the bacteria towards glycolysis decreases slowly, but half of the bacteria are still viable after one month. When confined within a mineral environment, bacteria do not form colonies. The exchange of chemical signals between isolated bacteria rather than aggregates can then be studied, a point that could be very important for 'quorum sensing'.

  14. Structural manipulation of colloidal silica

    NASA Astrophysics Data System (ADS)

    Roose, Jesse; Rischka, Klaus; Thiel, Karsten; Hartwig, Andreas

    2011-05-01

    Structural properties of the nanosized silica Ludox TMA with novel functionalizations have been investigated. Silica is stabilized in aqueous solution at a pH value higher than the pKa of silicic acid. A surface modification consisting of poly(p-benzamide)s functionalized with derivatized nucleobases on the C-terminus and cationic pyridinium functions on the N-terminus of the polymer chain was carried out. Due to the negatively charged surface, strong physisorption of the cationic pyridinium functions occurs. It is possible to stabilize diluted solutions of silica without agglomeration in solvents with various polarities by using pyridinium cations. Defined structures could be created according to the hydrogen donor/acceptor potential of the introduced nucleobase. Surprisingly the interactions between the same nucleobases are already sufficient for strong particle-particle interactions. Dramatic effects on the structural behavior are characterized by PCS, (S)TEM and EFTEM.

  15. 21 CFR 584.700 - Hydrophobic silicas.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...: (i) Amorphous fumed hydrophobic silica: Not less than 99.0 percent silicon dioxide after ignition... dichlorodimethylsilane. (ii) Precipated hydrophobic silica: Not less than 94.0 percent silicon dioxide after...

  16. 21 CFR 584.700 - Hydrophobic silicas.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...: (i) Amorphous fumed hydrophobic silica: Not less than 99.0 percent silicon dioxide after ignition... dichlorodimethylsilane. (ii) Precipated hydrophobic silica: Not less than 94.0 percent silicon dioxide after...

  17. 21 CFR 584.700 - Hydrophobic silicas.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...: (i) Amorphous fumed hydrophobic silica: Not less than 99.0 percent silicon dioxide after ignition... dichlorodimethylsilane. (ii) Precipated hydrophobic silica: Not less than 94.0 percent silicon dioxide after...

  18. Physisorbed Water on Silica at Mars Temperatures

    NASA Technical Reports Server (NTRS)

    Sutter, B.; Sriwatanapongse, W.; Quinn, R.; Klug, C.; Zent, A.

    2002-01-01

    The usefulness of nuclear magnetic resonance spectroscopy in probing water interactions on silica at Mars temperatures is discussed. Results indicate that two types of water occur with silica at Mars temperatures. Additional information is contained in the original extended abstract.

  19. Silica Materials for Medical Applications

    PubMed Central

    Vallet-Regí, María; Balas, Francisco

    2008-01-01

    The two main applications of silica-based materials in medicine and biotechnology, i.e. for bone-repairing devices and for drug delivery systems, are presented and discussed. The influence of the structure and chemical composition in the final characteristics and properties of every silica-based material is also shown as a function of the both applications presented. The adequate combination of the synthesis techniques, template systems and additives leads to the development of materials that merge the bioactive behavior with the drug carrier ability. These systems could be excellent candidates as materials for the development of devices for tissue engineering. PMID:19662110

  20. Optothermal nonlinearity of silica aerogel

    NASA Astrophysics Data System (ADS)

    Braidotti, Maria Chiara; Gentilini, Silvia; Fleming, Adam; Samuels, Michiel C.; Di Falco, Andrea; Conti, Claudio

    2016-07-01

    We report on the characterization of silica aerogel thermal optical nonlinearity, obtained by z-scan technique. The results show that typical silica aerogels have nonlinear optical coefficient similar to that of glass (≃10-12 m2/W), with negligible optical nonlinear absorption. The nonlinear coefficient can be increased to values in the range of 10-10 m2/W by embedding an absorbing dye in the aerogel. This value is one order of magnitude higher than that observed in the pure dye and in typical highly nonlinear materials like liquid crystals.

  1. Removal of dissolved and colloidal silica

    DOEpatents

    Midkiff, William S.

    2002-01-01

    Small amorphous silica particles are used to provide a relatively large surface area upon which silica will preferentially adsorb, thereby preventing or substantially reducing scaling caused by deposition of silica on evaporative cooling tower components, especially heat exchange surfaces. The silica spheres are contacted by the cooling tower water in a sidestream reactor, then separated using gravity separation, microfiltration, vacuum filtration, or other suitable separation technology. Cooling tower modifications for implementing the invention process have been designed.

  2. The properties of silica-gelatin composites

    NASA Astrophysics Data System (ADS)

    Stavinskaya, O. N.; Laguta, I. V.

    2010-06-01

    Silica-gelatin composites with various silica-to-gelatin ratios were obtained. The influence of high-dispersity silica on the swelling of composites in water and desorption of pyridoxine and thiamine vitamins incorporated into the material was studied. The addition of silica to gelatin was shown to increase the time of the dissolution of the materials in aqueous medium and decelerate the desorption of vitamins.

  3. A cleavable silica-binding affinity tag for rapid and inexpensive protein purification.

    PubMed

    Coyle, Brandon L; Baneyx, François

    2014-10-01

    We describe a new affinity purification tag called Car9 that confers proteins to which it is fused micromolar affinity for unmodified silica. When appended to the C-terminus of GFPmut2 through a flexible linker, Car9 promotes efficient adsorption to silica gel and the fusion protein can be released from the particles by incubation with L-lysine. Using a silica gel column and the lysine elution approach in fast protein liquid chromatography (FPLC) mode, Car9-tagged versions of GFPmut2, mCherry and maltose binding protein (MBP) can be recovered from clarified lysates with a purity of 80-90%. Capitalizing on silica's ability to handle large pressure drops, we further show that it is possible to go from cell lysates to purified protein in less than 15 min using a fully disposable device. Finally, we demonstrate that the linker-Car9 region is susceptible to proteolysis by E. coli OmpT and take advantage of this observation to excise the C-terminal extension of GFPmut2-Car9 by incubating purified fusion protein with cells that overproduce the outer membrane protease OmpT. The set of strategies described herein, should reduce the cost of affinity purification by at least 10-fold, cut down purification times to minutes, and allow for the production of proteins with native (or nearly native) termini from their C-terminally-tagged versions.

  4. Plate heights below 50 nm for protein electrochromatography using silica colloidal crystals.

    PubMed

    Wei, Bingchuan; Malkin, Douglas S; Wirth, Mary J

    2010-12-15

    Silica colloidal crystals formed from 330 nm nonporous silica spheres inside of 75 μm i.d. fused silica capillaries were evaluated for the efficiency of capillary electrochromatography of proteins. Three proteins, ribonuclease A, cytochrome C, and lysozyme, each covalently labeled with fluorophor, were well separated over a distance of 1 cm by isocratic electromigration, using 40:60 acetonitrile/water with 0.1% formic acid. A van Deemter plot showed that the plate height for lysozyme, which was the purest of the three proteins, was diffusion-limited for electric fields ranging from 400 to 1400 V/cm. The plate height for lysozyme was below 50 nm at almost all of the migration velocities, and it approached 10 nm at the highest velocity. Eddy diffusion was negligible. Lysozyme migrated over a 12 mm separation length with more than 10(6) plates in 1.5 min. These results indicate that silica colloidal crystals are well suited for electrically driven separations of large, highly charged analytes such as proteins. The 10(6) plates observed for a separation length of barely more than a centimeter means they are potentially valuable for miniaturized separations in microchip and lab-on-a-chip devices.

  5. Use of vancomycin silica stationary phase in packed capillary electrochromatography I. Enantiomer separation of basic compounds.

    PubMed

    Desiderio, C; Aturki, Z; Fanali, S

    2001-02-01

    Chiral separation of basic compounds was achieved by using 75 or 100 microm ID fused-silica capillaries packed with a vanoomycin-modified diol silica stationary phase. The capillary was firstly packed for about 12 cm with a slurry mixture composed of diolsilica (3:1) then with the vancomycin modified diol-silica (3:1) (23 cm), and finally with diol-silica (3:1) for about 2 cm. Frits were prepared by a heating wire at the two ends of the capillary; the detector window was prepared at 8.5 cm from the end of the capillary where vancomycin was not present. The influence of the mobile phase composition (pH and concentration, organic modifier type and concentration) on the velocity of the electroosmotic flow, chiral resolution and enantioselectivity was studied. Good enantiomeric resolution was achieved for atenolol, oxprenolol, propranolol, and venlafaxine using a mobile phase composition of 100 mM ammonium acetate solution (pH 6)/water/acetonitrile (5:5:90 v/v/v) while for terbutaline a mixture of 5:15:80 v/v/v provided the best separations. The use of methanol instead of acetonitrile caused a general increase of enantiomer resolution of the studied compounds together with a reduction of efficiency and detector response. However, the combination of acetonitrile and methanol in the mobile phase (as, e.g., 10% methanol and 80% acetonitrile) allowed to improve the enantiomer resolution with satisfactory detector response.

  6. Depth-fused 3D imagery on an immaterial display.

    PubMed

    Lee, Cha; Diverdi, Stephen; Höllerer, Tobias

    2009-01-01

    We present an immaterial display that uses a generalized form of depth-fused 3D (DFD) rendering to create unencumbered 3D visuals. To accomplish this result, we demonstrate a DFD display simulator that extends the established depth-fused 3D principle by using screens in arbitrary configurations and from arbitrary viewpoints. The feasibility of the generalized DFD effect is established with a user study using the simulator. Based on these results, we developed a prototype display using one or two immaterial screens to create an unencumbered 3D visual that users can penetrate, examining the potential for direct walk-through and reach-through manipulation of the 3D scene. We evaluate the prototype system in formative and summative user studies and report the tolerance thresholds discovered for both tracking and projector errors.

  7. The ROC Curves of Fused Independent Classification Systems

    DTIC Science & Technology

    2008-09-01

    spectral settings arises in many fields of study; in medicine, the detection of a cancer; in marketing , the detection of the best customer base; in the...THE ROC CURVES OF FUSED INDEPENDENT CLASSIFICATION SYSTEMS THESIS Michael B. Walsh AFIT/GAM/ENC/08/06 DEPARTMENT OF THE AIR FORCE AIR UNIVERSITY AIR...FORCE INSTITUTE OF TECHNOLOGY Wright-Patterson Air Force Base, Ohio APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED. The views expressed in this

  8. Chemical and Biological Sensing Utilizing Fused Bacteriorhodopsin Protein Hybrids

    DTIC Science & Technology

    2008-12-01

    Utilizing this purified DNA and a plasmid expression vector system, a fused protein hybrid consisting of maltose binding protein and bacterio-opsin has...prior to transcription, or post-expression. Therefore, for the development of the current proof of concept biosensor, maltose binding protein has...been chosen for attachment to the N-terminus of bR by genetic fusion and subsequent expression in E. coli. The maltose binding protein is a

  9. 30 CFR 75.601-3 - Short circuit protection; dual element fuses; current ratings; maximum values.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Short circuit protection; dual element fuses... Trailing Cables § 75.601-3 Short circuit protection; dual element fuses; current ratings; maximum values. Dual element fuses having adequate current-interrupting capacity shall meet the requirements for...

  10. 30 CFR 75.601-3 - Short circuit protection; dual element fuses; current ratings; maximum values.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Short circuit protection; dual element fuses... Trailing Cables § 75.601-3 Short circuit protection; dual element fuses; current ratings; maximum values. Dual element fuses having adequate current-interrupting capacity shall meet the requirements for...

  11. 30 CFR 75.601-3 - Short circuit protection; dual element fuses; current ratings; maximum values.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Short circuit protection; dual element fuses... Trailing Cables § 75.601-3 Short circuit protection; dual element fuses; current ratings; maximum values. Dual element fuses having adequate current-interrupting capacity shall meet the requirements for...

  12. Hydrodynamically mediated macrophyte silica dynamics.

    PubMed

    Schoelynck, J; Bal, K; Puijalon, S; Meire, P; Struyf, E

    2012-11-01

    In most aquatic ecosystems, hydrodynamic conditions are a key abiotic factor determining species distributions and abundance of aquatic plants. Resisting stress and keeping an upright position often relies on investment in tissue reinforcement, which is costly to produce. Silica could provide a more economical alternative. Two laboratory experiments were conducted to measure the response of two submerged species, Egeria densa Planch. and Limnophila heterophylla (Roxb.) Benth., to dissolved silicic acid availability and exposure to hydrodynamic stress. The results were verified with a third species in a field study (Nuphar lutea (L.) Smith). Biogenic silica (BSi) concentration in both stems and leaves increases with increasing dissolved silica availability but also with the presence of hydrodynamic stress. We suggest that the inclusion of extra silica enables the plant to alternatively invest its energy in the production of lignin and cellulose. Although we found no significant effects of hydrodynamic stress on cellulose or lignin concentrations either in the laboratory or in the field, BSi was negatively correlated with cellulose concentration and positively correlated with lignin concentration in samples collected in the field study. This implies that the plant might perform with equal energy efficiency in both standing and running water environments. This could provide submerged species with a tool to respond to abiotic factors, to adapt to new ecological conditions and hence potentially colonise new environments.

  13. Characterization of copper and nichrome wires for safety fuse

    NASA Astrophysics Data System (ADS)

    Murdani, E.

    2016-11-01

    Fuse is an important component of an electrical circuit to limiting the current through the electrical circuit for electrical equipment safety. Safety fuses are made of a conductor such as copper and nichrome wires. The aim of this research was to determine the maximum current that can flow in the conductor wires (copper and nichrome). In the experiment used copper and nichrome wires by varying the length of wires (0.2 cm to 20 cm) and diameter of wires (0.1, 0.2, 0.3, 0.4 and 0.5) mm until maximum current reached that marked by melted or broken wire. From this experiment, it will be obtained the dependences data of maximum current to the length and diameter of wires. All data are plotted and it's known as a standard curve. The standard curve will provide an alternative choice of replacing fuse wire according to the maximum current requirement, including the wire type (copper and nichrome wires) and wire dimensions (length and diameter of wire).

  14. FUSE observations of Hot Gas in the Carina Nebula

    NASA Astrophysics Data System (ADS)

    Iping, R. C.; Sonneborn, G.; Jenkins, E. B.; Bowen, D. V.

    2002-06-01

    We present an analysis of interstellar O VI 1031.93 toward several O and WR stars in the Tr 16 cluster, based on high-resolution spectra obtained with the FUSE satellite. The objective of this study is to investigate the distribution of O VI absorption within the cluster. The target stars include CPD-59D2628, CPD-59D2627, CPD-59D2632, HDE 303308, CPD -59 2600, CPD -59 2603, HD093205, HD093204, HD93162, HD093250 and HD 93308 (Eta Car). Two interstellar molecular hydrogen transitions, Lyman 6-0 P(3) 1031.19 and Lyman 6-0 R(4) 1032.35, are located very close to the interstellar O VI feature. These lines have been modelled by analyzing other P(3) and R(4) transitions in the FUSE spectrum. The column densities and distribution of the O VI ion in the Carina Nebulae is determined by using Gaussian profile fitting procedures. These results are compared with FUSE observations of other OB stars in the general vicinity of Carina, but outside the active region. This work has been supported in part by NASA grants NAG5-11137 to Catholic University of America and NASA contract NAS5-32985 to Johns Hopkins University.

  15. FUSE Observations of the Herbig Be star HD 100546

    NASA Astrophysics Data System (ADS)

    Deleuil, M.; Roberge, A.; Feldman, P. D.; Lecavelier des Etangs, A.; Vidal-Madjar, A.; Bouret, J.-C.; Ferlet, R.; André, M.; Moos, H. W.; Blair, W. P.; FUSE Science Team

    2000-12-01

    The first observation of the Herbig Be star HD100546 in the far UV has been made by the Far Ultraviolet Spectroscopic Explorer (FUSE). The spectra reveal numerous circumstellar absorption lines arising not only from the fine structure levels of refractory species like Fe 2, but also from neutral volatiles: C 1, C 1*, N 1 and N 1*. H2 transitions detected in absorption probe the cold gaseous portion of the circumstellar environment. Strong unexpected emission lines are also observed below 1100 Å, where the stellar continuum flux is very low. In particular, broad C 3 and O 6 emission lines demonstrate the presence of hot, dense, collisionally ionized gas which may be related to an extended chromosphere and/or corona. These features reveal a complex circumstellar environment, with wide range of temperatures and physical conditions. Based on observations obtained for the Guaranteed Time Team by the NASA-CNES-CSA FUSE mission. FUSE is operated for NASA by the John Hopkins University under NASA contract NASS-32985.

  16. Psychophysical assessments of image-sensor fused imagery.

    PubMed

    Krebs, William K; Sinai, Michael J

    2002-01-01

    The goal of this study was to determine the perceptual advantages of multiband sensor-fused (achromatic and chromatic) imagery over conventional single-band nighttime (image-intensified and infrared) imagery for a wide range of visual tasks, including detection, orientation, and scene recognition. Participants were 151 active-duty military observers whose reaction time and accuracy scores were recorded during a visual search task. Data indicate that sensor fusion did not improve performance relative to that obtained with single-band imagery on a target detection task but did facilitate object recognition, judgments of spatial orientation, and scene recognition. Observers' recognition and orientation judgments were improved by the emergent information within the image-fused imagery (i.e., combining dominant information from two or more sensors into a single displayed image). Actual or potential applications of this research include the deployment of image-sensor fused systems for automobile, aviation, and maritime displays to increase operators' visual processing during low-light conditions.

  17. A hierarachical data structure representation for fusing multisensor information

    SciTech Connect

    Maren, A.J.; Pap, R.M.; Harston, C.T.

    1989-12-31

    A major problem with MultiSensor Information Fusion (MSIF) is establishing the level of processing at which information should be fused. Current methodologies, whether based on fusion at the data element, segment/feature, or symbolic levels, are each inadequate for robust MSIF. Data-element fusion has problems with coregistration. Attempts to fuse information using the features of segmented data relies on a Presumed similarity between the segmentation characteristics of each data stream. Symbolic-level fusion requires too much advance processing (including object identification) to be useful. MSIF systems need to operate in real-time, must perform fusion using a variety of sensor types, and should be effective across a wide range of operating conditions or deployment environments. We address this problem through developing a new representation level which facilitates matching and information fusion. The Hierarchical Data Structure (HDS) representation, created using a multilayer, cooperative/competitive neural network, meets this need. The HDS is an intermediate representation between the raw or smoothed data stream and symbolic interpretation of the data. it represents the structural organization of the data. Fused HDSs will incorporate information from multiple sensors. Their knowledge-rich structure aids top-down scene interpretation via both model matching and knowledge-based region interpretation.

  18. A hierarachical data structure representation for fusing multisensor information

    SciTech Connect

    Maren, A.J. . Space Inst.); Pap, R.M.; Harston, C.T. )

    1989-01-01

    A major problem with MultiSensor Information Fusion (MSIF) is establishing the level of processing at which information should be fused. Current methodologies, whether based on fusion at the data element, segment/feature, or symbolic levels, are each inadequate for robust MSIF. Data-element fusion has problems with coregistration. Attempts to fuse information using the features of segmented data relies on a Presumed similarity between the segmentation characteristics of each data stream. Symbolic-level fusion requires too much advance processing (including object identification) to be useful. MSIF systems need to operate in real-time, must perform fusion using a variety of sensor types, and should be effective across a wide range of operating conditions or deployment environments. We address this problem through developing a new representation level which facilitates matching and information fusion. The Hierarchical Data Structure (HDS) representation, created using a multilayer, cooperative/competitive neural network, meets this need. The HDS is an intermediate representation between the raw or smoothed data stream and symbolic interpretation of the data. it represents the structural organization of the data. Fused HDSs will incorporate information from multiple sensors. Their knowledge-rich structure aids top-down scene interpretation via both model matching and knowledge-based region interpretation.

  19. Flow field velocity measurements for non-isothermal systems. [of chemically reactive flow inside fused silica CVD reactor vessels

    NASA Technical Reports Server (NTRS)

    Johnson, E. J.; Hyer, P. V.; Culotta, P. W.; Clark, I. O.

    1991-01-01

    Experimental techniques which can be potentially utilized to measure the gas velocity fields in nonisothermal CVD systems both in ground-based and space-based investigations are considered. The advantages and disadvantages of a three-component laser velocimetry (LV) system that was adapted specifically for quantitative determination of the mixed convective flows in a chamber for crystal growth and film formation by CVD are discussed. Data from a horizontal research CVD reactor indicate that current models for the effects of thermophoretic force are not adequate to predict the thermophoretic bias in arbitrary flow configurations. It is concluded that LV techniques are capable of characterizing the fluid dynamics of a CVD reactor at typical growth temperatures. Thermal effects are shown to dominate and stabilize the fluid dynamics of the reactor. Heating of the susceptor increases the gas velocities parallel to the face of a slanted susceptor by up to a factor of five.

  20. Thin fused silica optics for a few arcsec angular resolution and large collecting area x-ray telescope

    NASA Astrophysics Data System (ADS)

    Citterio, O.; Civitani, M. M.; Pareschi, G.; Basso, S.; Campana, S.; Conconi, P.; Ghigo, M.; Mattaini, E.; Moretti, A.; Parodi, G.; Tagliaferri, G.

    2013-09-01

    The implementation of a X-ray mission with high imaging capabilities, similar to those achieved with Chandra (< 1 arcsec Half Energy Width, HEW), but with a much larger throughput is a very attractive perspective, even if challenging. For such a mission the scientific opportunities, in particular for the study of the early Universe, would remain at the state of the art for the next decades. At the beginning of the new millennium the XEUS mission has been proposed, with an effective area of several m2 and an angular resolution better than 2 arcsec HEW. Unfortunately, after the initial study, this mission was not implemented, mainly due to the costs and the low level of technology readiness. Currently the most advanced proposal for such a kind of mission is the SMART-X project, led by CfA and involving several other US Institutes. This project is based on adjustable segments of thin foil mirrors with piezo-electric actuators, aiming to achieve an effective area < 2 m2 at 1 keV and an angular resolution better than 1 arcsec HEW. Another attractive technology to realize an X-ray telescope with similar characteristics is being developed at NASA/Goddard. In this case the mirrors are based on Si substrates that are super-polished and figured starting from a bulky Si ingot, from which they are properly cut. Here we propose an alternative method based on precise direct grinding, figuring and polishing of thin (a few mm) glass shells with innovative deterministic polishing methods. This is followed by a final correction via ion figuring to obtain the desired accuracy in order to achieve the 1 arc sec HEW requirement. For this purpose, a temporary stiffening structure is used to support the shell from the polishing operations up to its integration in the telescope supporting structure. We will present the technological process under development, the results achieved so far and some mission scenarios based on this kind of optics, aiming to achieve an effective area more than 10 times larger than Chandra and an angular resolution of 1 arcsec HEW on axis and of a few arcsec off-axis across a large field of view (1 deg in diameter).

  1. Thin fused silica optics for a high angular resolution and large collecting area X Ray telescope after Chandra

    NASA Astrophysics Data System (ADS)

    Pareschi, Giovanni; Citterio, Oberto; Civitani, Marta M; Basso, Stefano; Campana, Sergio; Conconi, Paolo; Ghigo, Mauro; Mattaini, Enrico; Moretti, Alberto; Parodi, Giancarlo; Tagliaferri, Gianpiero

    2014-08-01

    The implementation of an X-ray mission with high imaging capabilities, similar to those achieved with Chandra (<1 arcsec Half Energy Width, HEW), but with a much larger throughput is very attractive, even if challenging. For such a mission the scientific opportunities, in particular for the study of the early Universe, would remain at the state of the art for the next decades. Initially the ESA-led XEUS mission was proposed, with an effective area of several m2 and an angular resolution better than 2 arcsec HEW. Unfortunately, this mission was not implemented, mainly due to the costs and the low level of technology readiness. Currently the most advanced proposal for such a mission is the SMART-X project, led by CfA together with other US institutes. This project is based on adjustable segments of thin foil mirrors with piezo-electric actuators, aiming to achieve an effective area >2 m2 at 1 keV and an angular resolution better than 1 arcsec HEW. Another attractive technology to realize an X-ray telescope with similar characteristics is being developed at NASA/Goddard. In this case the mirrors are based on Si substrates that are super-polished and figured starting from a bulky Si ingot, from which they are properly cut. Here we propose an alternative method based on precise direct grinding, figuring and polishing of thin (a few mm) glass shells with innovative deterministic polishing methods. This is followed by a final correction via ion figuring to obtain the desired accuracy. For this purpose, a temporary stiffening structure is used to support the shell from the polishing operations up to its integration in the telescope supporting structure. This paper deals with the technological process under development, the results achieved so far and some mission scenarios based on this kind of optics, aiming to achieve an effective area more than 10 times larger than Chandra and an angular resolution of 1 arcsec HEW on axis and of a few arcsec off-axis across a large field of view (1o in diameter).

  2. High-performance fused indium gallium arsenide/silicon photodiode

    NASA Astrophysics Data System (ADS)

    Kang, Yimin

    Modern long haul, high bit rate fiber-optic communication systems demand photodetectors with high sensitivity. Avalanche photodiodes (APDs) exhibit superior sensitivity performance than other types of photodetectors by virtual of its internal gain mechanism. This dissertation work further advances the APD performance by applying a novel materials integration technique. It is the first successful demonstration of wafer fused InGaAs/Si APDs with low dark current and low noise. APDs generally adopt separate absorption and multiplication (SAM) structure, which allows independent optimization of materials properties in two distinct regions. While the absorption material needs to have high absorption coefficient in the target wavelength range to achieve high quantum efficiency, it is desirable for the multiplication material to have large discrepancy between its electron and hole ionization coefficients to reduce noise. According to these criteria, InGaAs and Si are the ideal materials combination. Wafer fusion is the enabling technique that makes this theoretical ideal an experimental possibility. APDs fabricated on the fused InGaAs/Si wafer with mesa structure exhibit low dark current and low noise. Special device fabrication techniques and high quality wafer fusion reduce dark current to nano ampere level at unity gain, comparable to state-of-the-art commercial III/V APDs. The small excess noise is attributed to the large difference in ionization coefficients between electrons and holes in silicon. Detailed layer structure designs are developed specifically for fused InGaAs/Si APDs based on principles similar to those used in traditional InGaAs/InP APDs. An accurate yet straightforward technique for device structural parameters extraction is also proposed. The extracted results from the fabricated APDs agree with device design parameters. This agreement also confirms that the fusion interface has negligible effect on electric field distributions for devices fabricated

  3. Superhydrophobicity of silica nanoparticles modified with polystyrene

    NASA Astrophysics Data System (ADS)

    Sun, X. L.; Fan, Z. P.; Zhang, L. D.; Wang, L.; Wei, Z. J.; Wang, X. Q.; Liu, W. L.

    2011-01-01

    Polystyrene/silica nanoparticles were prepared by radical polymerization of silica nanoparticles possessing vinyl groups and styrene with benzoyl peroxide. The resulting vinyl silica nanoparticles, polystyrene/silica nanoparticles were characterized by means of Fourier transformation infrared spectroscopy, scanning electron microscopy and UV-vis absorption spectroscopy. The results indicated that polystyrene had been successfully grafted onto vinyl silica nanoparticles via covalent bond. The morphological structure of polystyrene/silica nanoparticles film, investigated by scanning electron microscopy, showed a characteristic rough structure. Surface wetting properties of the polystyrene/silica nanoparticles film were evaluated by measuring water contact angle and the sliding angle using a contact angle goniometer, which were measured to be 159° and 2°, respectively. The excellent superhydrophobic property enlarges potential applications of the superhydrophobic surfaces.

  4. Facile preparation of organic-silica hybrid monolith for capillary hydrophilic liquid chromatography based on "thiol-ene" click chemistry.

    PubMed

    Chen, Ming-Luan; Zhang, Jun; Zhang, Zheng; Yuan, Bi-Feng; Yu, Qiong-Wei; Feng, Yu-Qi

    2013-04-05

    In this work, a one-step approach to facile preparation of organic-inorganic hybrid monoliths was successfully developed. After vinyl-end organic monomers and azobisisobutyronitrile (AIBN) were mixed with hydrolyzed tetramethoxysilane (TMOS) and 3-mercaptopropyltrimethoxysilane (MPTMS), the homogeneous mixture was introduced into a fused-silica capillary for simultaneous polycondensation and "thiol-ene" click reaction to form the organic-silica hybrid monoliths. By employing this strategy, two types of organic-silica hybrid monoliths with positively charged quaternary ammonium and amide groups were prepared, respectively. The functional groups were successfully introduced onto the monoliths during the sol-gel process with "thiol-ene" click reaction, which was demonstrated by ζ-potential assessment, energy dispersive X-ray spectroscopy (EDX), and Fourier transform infrared (FT-IR) spectroscopy. The porous structure of the prepared monolithic columns was examined by scanning electron microscopy (SEM), nitrogen adsorption-desorption measurement, and mercury intrusion porosimetry. These results indicate the prepared organic-silica hybrid monoliths possess homogeneous column bed, large specific surface area, good mechanical stability, and excellent permeability. The prepared monolithic columns were then applied for anion-exchange/hydrophilic interaction liquid chromatography. Different types of analytes, including benzoic acids, inorganic ions, nucleosides, and nucleotides, were well separated with high column efficiency around 80,000-130,000 plates/m. Taken together, we present a facile and universal strategy to prepare organic-silica hybrid monoliths with a variety of organic monomers using one-step approach.

  5. Silica Lubrication in Faults (Invited)

    NASA Astrophysics Data System (ADS)

    Rowe, C. D.; Rempe, M.; Lamothe, K.; Kirkpatrick, J. D.; White, J. C.; Mitchell, T. M.; Andrews, M.; Di Toro, G.

    2013-12-01

    Silica-rich rocks are common in the crust, so silica lubrication may be important for causing fault weakening during earthquakes if the phenomenon occurs in nature. In laboratory friction experiments on chert, dramatic shear weakening has been attributed to amorphization and attraction of water from atmospheric humidity to form a 'silica gel'. Few observations of the slip surfaces have been reported, and the details of weakening mechanism(s) remain enigmatic. Therefore, no criteria exist on which to make comparisons of experimental materials to natural faults. We performed a series of friction experiments, characterized the materials formed on the sliding surface, and compared these to a geological fault in the same rock type. Experiments were performed in the presence of room humidity at 2.5 MPa normal stress with 3 and 30 m total displacement for a variety of slip rates (10-4 - 10-1 m/s). The friction coefficient (μ) reduced from >0.6 to ~0.2 at 10-1 m/s, but only fell to ~0.4 at 10-2 - 10-4 m/s. The slip surfaces and wear material were observed using laser confocal Raman microscopy, electron microprobe, X-ray diffraction, and transmission electron microscopy. Experiments at 10-1 m/s formed wear material consisting of ≤1 μm powder that is aggregated into irregular 5-20 μm clumps. Some material disaggregated during analysis with electron beams and lasers, suggesting hydrous and unstable components. Compressed powder forms smooth pavements on the surface in which grains are not visible (if present, they are <100 nm). Powder contains amorphous material and as yet unidentified crystalline and non-crystalline forms of silica (not quartz), while the worn chert surface underneath shows Raman spectra consistent with a mixture of quartz and amorphous material. If silica amorphization facilitates shear weakening in natural faults, similar wear materials should be formed, and we may be able to identify them through microstructural studies. However, the sub

  6. Capillary electrochromatography with monolithic silica column: I. Preparation of silica monoliths having surface-bound octadecyl moieties and their chromatographic characterization and applications to the separation of neutral and charged species.

    PubMed

    Allen, Darin; El Rassi, Ziad

    2003-01-01

    Monolithic silica columns with surface-bound octadecyl (C18) moieties have been prepared by a sol-gel process in 100 microm ID fused-silica capillaries for reversed-phase capillary electrochromatography of neutral and charged species. The reaction conditions for the preparation of the C18-silica monoliths were optimized for maximum surface coverage with octadecyl moieties in order to maximize retention and selectivity toward neutral and charged solutes with a sufficiently strong electroosmotic flow (> 2 mm/s) to yield rapid analysis time. Furthermore, the effect of the pore-tailoring process on the silica monoliths was performed over a wide range of treatment time with 0.010 M ammonium hydroxide solution in order to determine the optimum time and conditions that yield mesopores of narrow pore size distribution that result in high separation efficiency. Under optimum column fabrication conditions and optimum mobile phase composition and flow velocity, the average separation efficiency reached 160 000 plates/m, a value comparable to that obtained on columns packed with 3 microm C18-silica particles with the advantages of high permeability and virtually no bubble formation. The optimized monolithic C18-silica columns were evaluated for their retention properties toward neutral and charged analytes over a wide range of mobile phase compositions. A series of dimensionless retention parameters were evaluated and correlated to solute polarity and electromigration property. A dimensionless mobility modulus was introduced to describe charged solute migration and interaction behavior with the monolithic C18-silica in a counterflow regime during capillary electrochromatography (CEC )separations. The mobility moduli correlated well with the solute hydrophobic character and its charge-to-mass ratio.

  7. Organically modified silicas on metal nanowires.

    PubMed

    Dean, Stacey L; Stapleton, Joshua J; Keating, Christine D

    2010-09-21

    Organically modified silica coatings were prepared on metal nanowires using a variety of silicon alkoxides with different functional groups (i.e., carboxyl groups, polyethylene oxide, cyano, dihydroimidazole, and hexyl linkers). Organically modified silicas were deposited onto the surface of 6-μm-long, ∼300-nm-wide, cylindrical metal nanowires in suspension by the hydrolysis and polycondensation of silicon alkoxides. Syntheses were performed at several ratios of tetraethoxysilane to an organically modified silicon alkoxide to incorporate desired functional groups into thin organosilica shells on the nanowires. These coatings were characterized using transmission electron microscopy, X-ray photoelectron spectroscopy, and infrared spectroscopy. All of the organically modified silicas prepared here were sufficiently porous to allow the removal of the metal nanowire cores by acid etching to form organically modified silica nanotubes. Additional functionality provided to the modified silicas as compared to unmodified silica prepared using only tetraethoxysilane precursors was demonstrated by chromate adsorption on imidazole-containing silicas and resistance to protein adsorption on polyethyleneoxide-containing silicas. Organically modified silica coatings on nanowires and other nano- and microparticles have potential application in fields such as biosensing or nanoscale therapeutics due to the enhanced properties of the silica coatings, for example, the prevention of biofouling.

  8. Silica-Immobilized Enzyme Reactors

    DTIC Science & Technology

    2007-08-01

    relief from the symptoms of inflammation and pain Silica-IMERs 10 and is the mode of action of drugs such as aspirin and ibuprofen .[61] Serotonin...supports and using the enantiomeric selectivity of the enzyme to resolve racemic mixtures.[100] Immobilization onto supports with various pore sizes and...activity (~37%) and used as a packed- bed IMER to catalyze the racemic resolution of (S)-ketoprofen from its constituent enantiomers . The optically pure (S

  9. Chemical substitution in silica polymorph

    NASA Technical Reports Server (NTRS)

    Smith, J. V.; Steele, I. M.

    1984-01-01

    Ion and electron probe analyses are presented for trace elements (Al, Na, K, Li, Ti) in quartz, tridymite, cristobalite and melanophlogite. Quartz and melanophlogite show low levels of trace elements relative to tridymite and cristobalite. The previously determined alpha-beta inversion temperature decreases as the Al content of quartz increases. For all silica polymorphs, Al is greater than or equal to Na + K + Li on an atom basis, with the excess Al probably balanced by H.

  10. D/H Toward BD+28 4211: First FUSE Results

    NASA Technical Reports Server (NTRS)

    Sonneborne, George; Andre, M.; Oliveira, C.; Friedman, S. D.; Howk, J. C.; Kruk, J. W.; Moos, H. W.; Oegerle, W. R.; Sembach, K. R.; Chayer, P.; Fisher, Richard R. (Technical Monitor)

    2001-01-01

    The atomic deuterium-to-hydrogen abundance ratio has been evaluated for the sight line toward the hot O subdwarf BD+28(sup circ) 4211. High signal-to-noise ratio (S/N is approx. 100) observations covering the wavelength range 905 to 1187 angstroms at a wavelength resolving power of lambda/Delta/lambda at approx. 20,000 were obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite. BD+28(sup circ) 4211 is approx. 00 pc away with a total H I column density of approx. 10(exp 19)/sq cm, much higher than is typically found in the local interstellar medium (ISM). The deuterium column density was measured by analyzing several D I Lyman series transitions (Lyman delta, C, epsilon, eta, theta, iota with curve of growth and profile fitting techniques, after determining which lines were free of interference from other interstellar species and narrow stellar features. The neutral hydrogen column density was measured by an analysis of the Lyman-alpha profile using HST/Space Telescope Imaging Spectrograph (STIS) and Goddard High Resolution Spectrograph (GHRS) spectra. The stellar spectrum of BD+28(sup circ) 4211 was modelled to assist in determining the sensitivity of H I (Ly-alpha) and D I to the continuum placement and to identify stellar transitions. The D I and H I column densities, their uncertainties, and potential sources of systematic error will be presented. This work is based on data obtained for the FUSE Guaranteed Time Team by the NASA-CNES-CSA FUSE mission operated by the Johns Hopkins University. Financial support to U. S. participants has been provided in part by NASA contract NAS5-32985.

  11. Tree classification with fused mobile laser scanning and hyperspectral data.

    PubMed

    Puttonen, Eetu; Jaakkola, Anttoni; Litkey, Paula; Hyyppä, Juha

    2011-01-01

    Mobile Laser Scanning data were collected simultaneously with hyperspectral data using the Finnish Geodetic Institute Sensei system. The data were tested for tree species classification. The test area was an urban garden in the City of Espoo, Finland. Point clouds representing 168 individual tree specimens of 23 tree species were determined manually. The classification of the trees was done using first only the spatial data from point clouds, then with only the spectral data obtained with a spectrometer, and finally with the combined spatial and hyperspectral data from both sensors. Two classification tests were performed: the separation of coniferous and deciduous trees, and the identification of individual tree species. All determined tree specimens were used in distinguishing coniferous and deciduous trees. A subset of 133 trees and 10 tree species was used in the tree species classification. The best classification results for the fused data were 95.8% for the separation of the coniferous and deciduous classes. The best overall tree species classification succeeded with 83.5% accuracy for the best tested fused data feature combination. The respective results for paired structural features derived from the laser point cloud were 90.5% for the separation of the coniferous and deciduous classes and 65.4% for the species classification. Classification accuracies with paired hyperspectral reflectance value data were 90.5% for the separation of coniferous and deciduous classes and 62.4% for different species. The results are among the first of their kind and they show that mobile collected fused data outperformed single-sensor data in both classification tests and by a significant margin.

  12. Silica exposure and systemic vasculitis.

    PubMed Central

    Mulloy, Karen B

    2003-01-01

    Work in Department of Energy (DOE) facilities has exposed workers to multiple toxic agents leading to acute and chronic diseases. Many exposures were common to numerous work sites. Exposure to crystalline silica was primarily restricted to a few facilities. I present the case of a 63-year-old male who worked in DOE facilities for 30 years as a weapons testing technician. In addition to silica, other workplace exposures included beryllium, various solvents and heavy metals, depleted uranium, and ionizing radiation. In 1989 a painful macular skin lesion was biopsied and diagnosed as leukocytoclastic vasculitis. By 1992 he developed gross hematuria and dyspnea. Blood laboratory results revealed a serum creatinine concentration of 2.1 mg/dL, ethrythrocyte sedimentation rate of 61 mm/hr, negative cANCA (antineutrophil cytoplasmic antibody cytoplasmic pattern), positive pANCA (ANCA perinuclear pattern), and antiglomerular basement membrane negative. Renal biopsy showed proliferative (crescentric) and necrotizing glomerulonephritis. The patient's diagnoses included microscopic polyangiitis, systemic necrotizing vasculitis, leukocytoclastic vasculitis, and glomerulonephritis. Environmental triggers are thought to play a role in the development of an idiopathic expression of systemic autoimmune disease. Crystalline silica exposure has been linked to rheumatoid arthritis, scleroderma, systemic lupus erythematosus, rapidly progressive glomerulonephritis and some of the small vessel vasculitides. DOE workers are currently able to apply for compensation under the federal Energy Employees Occupational Illness Compensation Program (EEOICP). However, the only diseases covered by EEOICP are cancers related to radiation exposure, chronic beryllium disease, and chronic silicosis. PMID:14644669

  13. The Southern Ocean silica cycle

    NASA Astrophysics Data System (ADS)

    Tréguer, Paul J.

    2014-11-01

    The Southern Ocean is a major opal sink and plays a key role in the silica cycle of the world ocean. So far however, a complete cycle of silicon in the Southern Ocean has not been published. On one hand, Southern Ocean surface waters receive considerable amounts of silicic acid (dissolved silica, DSi) from the rest of the world ocean through the upwelling of the Circumpolar Deep Water, fed by contributions of deep waters of the Atlantic, Indian, and Pacific Oceans. On the other hand, the Southern Ocean exports a considerable flux of the silicic acid that is not used by diatoms in surface waters through the northward pathways of the Sub-Antarctic Mode Water, of the Antarctic Intermediate Water, and of the Antarctic Bottom Water. Thus the Southern Ocean is a source of DSi for the rest of the world ocean. Here we show that the Southern Ocean is a net importer of DSi: because there is no significant external input of DSi, the flux of DSi imported through the Circumpolar Deep Water pathway compensates the sink flux of biogenic silica in sediments.

  14. Fused Deposition Technique for Continuous Fiber Reinforced Thermoplastic

    NASA Astrophysics Data System (ADS)

    Bettini, Paolo; Alitta, Gianluca; Sala, Giuseppe; Di Landro, Luca

    2016-12-01

    A simple technique for the production of continuous fiber reinforced thermoplastic by fused deposition modeling, which involves a common 3D printer with quite limited modifications, is presented. An adequate setting of processing parameters and deposition path allows to obtain components with well-enhanced mechanical characteristics compared to conventional 3D printed items. The most relevant problems related to the simultaneous feeding of fibers and polymer are discussed. The properties of obtained aramid fiber reinforced polylactic acid (PLA) in terms of impregnation quality and of mechanical response are measured.

  15. Fused Deposition Technique for Continuous Fiber Reinforced Thermoplastic

    NASA Astrophysics Data System (ADS)

    Bettini, Paolo; Alitta, Gianluca; Sala, Giuseppe; Di Landro, Luca

    2017-02-01

    A simple technique for the production of continuous fiber reinforced thermoplastic by fused deposition modeling, which involves a common 3D printer with quite limited modifications, is presented. An adequate setting of processing parameters and deposition path allows to obtain components with well-enhanced mechanical characteristics compared to conventional 3D printed items. The most relevant problems related to the simultaneous feeding of fibers and polymer are discussed. The properties of obtained aramid fiber reinforced polylactic acid (PLA) in terms of impregnation quality and of mechanical response are measured.

  16. Processing of fused silicide coatings for carbon-based materials

    NASA Technical Reports Server (NTRS)

    Smialek, J. L.

    1982-01-01

    The processing and oxidation resistance of fused Al-Si and Ni-Si slurry coatings on ATJ graphite was studied. Ni-Si coatings in the 70 to 90 percent Si range were successfully processed to melt, wet, and bond to the graphite. The molten coatings also infiltrated the porosity in graphite and reacted with it to form SiC in the coating. Cyclic oxidation at 1200 C showed that these coatings were not totally protective because of local attack of the substrate, due to the extreme thinness of the coatings in combination with coating cracks.

  17. Shocks in Dense Clouds in the Vela Supernova Remnant: FUSE

    NASA Technical Reports Server (NTRS)

    Nichols, Joy; Sonneborn, George (Technical Monitor)

    2002-01-01

    We have obtained 8 LWRS FUSE spectra to study a recently identified interaction of the Vela supernova remnant with a dense cloud region along its western edge. The goal is to quantify the temperature, ionization, density, and abundance characteristics associated with this shock/dense cloud interface by means of UV absorption line studies. Our detection of high-velocity absorption line C I at +90 to +130 km/s with IUE toward a narrow region interior to the Vela SNR strongly suggests the Vela supernova remnant is interacting with a dense ISM or molecular cloud. The shock/dense cloud interface is suggested by (1) the rarity of detection of high-velocity C I seen in IUE spectra, (2) its very limited spatial distribution in the remnant, and (3) a marked decrease in X-ray emission in the region immediately west of the position of these stars where one also finds a 100 micron emission ridge in IRAS images. We have investigated the shock physics and general properties of this interaction region through a focussed UV absorption line study using FUSE spectra. We have FUSE data on OVI absorption lines observed toward 8 stars behind the Vela supernova remnant (SNR). We compare the OVI observations with IUE observations of CIV absorption toward the same stars. Most of the stars, which are all B stars, have complex continua making the extraction of absorption lines difficult. Three of the stars, HD 72088, HD 72089 and HD 72350, however, are rapid rotators (v sin i less than 100 km/s) making the derivation of absorption column densities much easier. We have measured OVI and CIV column densities for the "main component" (i.e. the low velocity component) for these stars. In addition, by removing the H2 line at 1032.35A (121.6 km/s relative to OVI), we find high velocity components of OVI at approximately 150 km/s that we attribute to the shock in the Vela SNR. The column density ratios and magnitudes are compared to both steady shock models and results of hydrodynamical SNR

  18. Silica Extraction at Mammoth Lakes, California

    SciTech Connect

    Bourcier, W; Ralph, W; Johnson, M; Bruton, C; Gutierrez, P

    2006-06-07

    The purpose of this project is to develop a cost-effective method to extract marketable silica (SiO{sub 2}) from fluids at the Mammoth Lakes, California geothermal power plant. Silica provides an additional revenue source for the geothermal power industry and therefore lowers the costs of geothermal power production. The use of this type of ''solution mining'' to extract resources eliminates the need for acquiring these resources through energy intensive and environmentally damaging mining technologies. We have demonstrated that both precipitated and colloidal silica can be produced from the geothermal fluids at Mammoth Lakes by first concentrating the silica to over 600 ppm using reverse osmosis (RO). The RO permeate can be used in evaporative cooling at the plant; the RO concentrate is used for silica and potentially other resource extraction (Li, Cs, Rb). Preliminary results suggest that silica recovery at Mammoth Lakes could reduce the cost of geothermal electricity production by 1.0 cents/kWh.

  19. One-pot preparation of glutathione-silica hybrid monolith for mixed-mode capillary liquid chromatography based on "thiol-ene" click chemistry.

    PubMed

    Lin, Zian; Tan, Xiaoqing; Yu, Ruifang; Lin, Jiashi; Yin, Xiaofei; Zhang, Lan; Yang, Huanghao

    2014-08-15

    A novel glutathione (GSH)-silica hybrid monolithic column synthesized via a combination of thiol-ene click reaction and one-pot process was described, where thiol-end GSH organic monomer and 2,2-azobisisobutyronitrile (AIBN) were mixed with hydrolyzed tetramethyloxysilane (TMOS) and γ-methacryloxypropyltrimethoxysilane (γ-MAPS) and then introduced into a fused-silica capillary for simultaneous polycondensation and "thiol-ene" click reaction to form the GSH-silica hybrid monolith. The effects of the molar ratio of TMOS/γ-MAPS, the amount of GSH, and the volume of porogen on the morphology, permeability and pore properties of the prepared GSH-silica hybrid monoliths were studied in detail. A uniform monolithic network with high porosity was obtained. A series of test compounds including alkylbenzenes, amides, and anilines were used to evaluate the retention behaviors of the GSH-silica hybrid monolithic column. The results demonstrated that the prepared GSH-silica hybrid monolith exhibited multiple interactions including hydrophobicity, hydrophilicity, as well as cation exchange interaction. The run-to-run, column-to-column and batch-to-batch reproducibilities of the GSH-silica hybrid monolith for phenols' retention were satisfactory with the relative standard deviations (RSDs) less than 1.3% (n=5), 2.6% (n=3) and 3.2% (n=3), respectively, indicating the effectiveness and practicability of the proposed method. In addition, the GSH-silica hybrid monolith was applied to the separation of nucleotides, peptides and protein tryptic digests, respectively. The successful applications suggested the potential of the GSH-silica hybrid monolith in complex sample analysis.

  20. Interaction between silica and hydrophobic cations.

    PubMed Central

    Depasse, J

    1978-01-01

    The interactions between silica and some molecules which have a high affinity for its surface have been studied. The hydrophobic properties and the positive charge of these molecules are likely to be responsible for their strong adsorption on to silica. These observations should be useful in research into new inhibitors of the effects of silica. One of the cations tested, chloroquine, has been shown to be an effective inhibitor of the haemolytic activity of quartz. PMID:204326

  1. Process for preparing polymer reinforced silica aerogels

    NASA Technical Reports Server (NTRS)

    Meador, Mary Ann B. (Inventor); Capadona, Lynn A. (Inventor)

    2011-01-01

    Process for preparing polymer-reinforced silica aerogels which comprises a one-pot reaction of at least one alkoxy silane in the presence of effective amounts of a polymer precursor to obtain a silica reaction product, the reaction product is gelled and subsequently subjected to conditions that promotes polymerization of the precursor and then supercritically dried to obtain the polymer-reinforced monolithic silica aerogels.

  2. Exploding metallic foil fuse modeling at Los Alamos

    SciTech Connect

    Lindemuth, I.R.; Reinovsky, R.E.; Goforth, J.H.

    1989-01-01

    A ''first-principles'' computational model of exploding metallic foil behavior has been developed at Los Alamos. The model couples zero-dimensional magnetohydrodynamics with ohmic heating and electrical circuit equations and uses the Los Alamos SESAME atomic data base computer library to determine the foil material's temperature- and density-dependent pressure, specific energy, and electrical conductivity. The model encompasses many previously successful empirical models and offers plausible physical explanations of phenomena not treated by the empirical models. In addition to addressing the electrical circuit performance of an exploding foil, the model provides information on the temporal evolution of the foil material's density, temperature, pressure, electrical conductivity, and expansion and translational velocities. In this paper, we report the physical insight gained by computational studies of two opening switch concepts being developed for application in an FCG-driven 1-MJ-class imploding plasma z-pinch experiment. The first concept considered is a ''conventional'' electrically exploded fuse, which has been demonstrated to operate at 16 MA driven by the 15-MJ-class FCG to be used in the 1 MJ implosion experiment. The second concept considered is a Type 2 explosively formed fuse (EFF), which has been demonstrated to operate at the 8 MA level by a 1-MJ-class FCG.

  3. A New Measure for Analyzing and Fusing Sequences of Objects.

    PubMed

    Goulermas, John Yannis; Kostopoulos, Alexandros; Mu, Tingting

    2016-05-01

    This work is related to the combinatorial data analysis problem of seriation used for data visualization and exploratory analysis. Seriation re-sequences the data, so that more similar samples or objects appear closer together, whereas dissimilar ones are further apart. Despite the large number of current algorithms to realize such re-sequencing, there has not been a systematic way for analyzing the resulting sequences, comparing them, or fusing them to obtain a single unifying one. We propose a new positional proximity measure that evaluates the similarity of two arbitrary sequences based on their agreement on pairwise positional information of the sequenced objects. Furthermore, we present various statistical properties of this measure as well as its normalized version modeled as an instance of the generalized correlation coefficient. Based on this measure, we define a new procedure for consensus seriation that fuses multiple arbitrary sequences based on a quadratic assignment problem formulation and an efficient way of approximating its solution. We also derive theoretical links with other permutation distance functions and present their associated combinatorial optimization forms for consensus tasks. The utility of the proposed contributions is demonstrated through the comparison and fusion of multiple seriation algorithms we have implemented, using many real-world datasets from different application domains.

  4. Covert photo classification by fusing image features and visual attributes.

    PubMed

    Lang, Haitao; Ling, Haibin

    2015-10-01

    In this paper, we study a novel problem of classifying covert photos, whose acquisition processes are intentionally concealed from the subjects being photographed. Covert photos are often privacy invasive and, if distributed over Internet, can cause serious consequences. Automatic identification of such photos, therefore, serves as an important initial step toward further privacy protection operations. The problem is, however, very challenging due to the large semantic similarity between covert and noncovert photos, the enormous diversity in the photographing process and environment of cover photos, and the difficulty to collect an effective data set for the study. Attacking these challenges, we make three consecutive contributions. First, we collect a large data set containing 2500 covert photos, each of them is verified rigorously and carefully. Second, we conduct a user study on how humans distinguish covert photos from noncovert ones. The user study not only provides an important evaluation baseline, but also suggests fusing heterogeneous information for an automatic solution. Our third contribution is a covert photo classification algorithm that fuses various image features and visual attributes in the multiple kernel learning framework. We evaluate the proposed approach on the collected data set in comparison with other modern image classifiers. The results show that our approach achieves an average classification rate (1-EER) of 0.8940, which significantly outperforms other competitors as well as human's performance.

  5. Ball driven type MEMS SAD for artillery fuse

    NASA Astrophysics Data System (ADS)

    Seok, Jin Oh; Jeong, Ji-hun; Eom, Junseong; Lee, Seung S.; Lee, Chun Jae; Ryu, Sung Moon; Oh, Jong Soo

    2017-01-01

    The SAD (safety and arming device) is an indispensable fuse component that ensures safe and reliable performance during the use of ammunition. Because the application of electronic devices for smart munitions is increasing, miniaturization of the SAD has become one of the key issues for next-generation artillery fuses. Based on MEMS technology, various types of miniaturized SADs have been proposed and fabricated. However, none of them have been reported to have been used in actual munitions due to their lack of high impact endurance and complicated explosive train arrangements. In this research, a new MEMS SAD using a ball driven mechanism, is successfully demonstrated based on a UV LIGA (lithography, electroplating and molding) process. Unlike other MEMS SADs, both high impact endurance and simple structure were achieved by using a ball driven mechanism. The simple structural design also simplified the fabrication process and increased the processing yield. The ball driven type MEMS SAD performed successfully under the desired safe and arming conditions of a spin test and showed fine agreement with the FEM simulation result, conducted prior to its fabrication. A field test was also performed with a grenade launcher to evaluate the SAD performance in the firing environment. All 30 of the grenade samples equipped with the proposed MEMS SAD operated successfully under the high-G setback condition.

  6. Planning the FUSE Mission Using the SOVA Algorithm

    NASA Technical Reports Server (NTRS)

    Lanzi, James; Heatwole, Scott; Ward, Philip R.; Civeit, Thomas; Calvani, Humberto; Kruk, Jeffrey W.; Suchkov, Anatoly

    2011-01-01

    Three documents discuss the Sustainable Objective Valuation and Attainability (SOVA) algorithm and software as used to plan tasks (principally, scientific observations and associated maneuvers) for the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite. SOVA is a means of managing risk in a complex system, based on a concept of computing the expected return value of a candidate ordered set of tasks as a product of pre-assigned task values and assessments of attainability made against qualitatively defined strategic objectives. For the FUSE mission, SOVA autonomously assembles a week-long schedule of target observations and associated maneuvers so as to maximize the expected scientific return value while keeping the satellite stable, managing the angular momentum of spacecraft attitude- control reaction wheels, and striving for other strategic objectives. A six-degree-of-freedom model of the spacecraft is used in simulating the tasks, and the attainability of a task is calculated at each step by use of strategic objectives as defined by use of fuzzy inference systems. SOVA utilizes a variant of a graph-search algorithm known as the A* search algorithm to assemble the tasks into a week-long target schedule, using the expected scientific return value to guide the search.

  7. Cellular membrane trafficking of mesoporous silica nanoparticles

    SciTech Connect

    Fang, I-Ju

    2012-01-01

    This dissertation mainly focuses on the investigation of the cellular membrane trafficking of mesoporous silica nanoparticles. We are interested in the study of endocytosis and exocytosis behaviors of mesoporous silica nanoparticles with desired surface functionality. The relationship between mesoporous silica nanoparticles and membrane trafficking of cells, either cancerous cells or normal cells was examined. Since mesoporous silica nanoparticles were applied in many drug delivery cases, the endocytotic efficiency of mesoporous silica nanoparticles needs to be investigated in more details in order to design the cellular drug delivery system in the controlled way. It is well known that cells can engulf some molecules outside of the cells through a receptor-ligand associated endocytosis. We are interested to determine if those biomolecules binding to cell surface receptors can be utilized on mesoporous silica nanoparticle materials to improve the uptake efficiency or govern the mechanism of endocytosis of mesoporous silica nanoparticles. Arginine-glycine-aspartate (RGD) is a small peptide recognized by cell integrin receptors and it was reported that avidin internalization was highly promoted by tumor lectin. Both RGD and avidin were linked to the surface of mesoporous silica nanoparticle materials to investigate the effect of receptor-associated biomolecule on cellular endocytosis efficiency. The effect of ligand types, ligand conformation and ligand density were discussed in Chapter 2 and 3. Furthermore, the exocytosis of mesoporous silica nanoparticles is very attractive for biological applications. The cellular protein sequestration study of mesoporous silica nanoparticles was examined for further information of the intracellular pathway of endocytosed mesoporous silica nanoparticle materials. The surface functionality of mesoporous silica nanoparticle materials demonstrated selectivity among the materials and cancer and normal cell lines. We aimed to determine

  8. Development, fabrication and test of a high purity silica heat shield

    NASA Technical Reports Server (NTRS)

    Rusert, E. L.; Drennan, D. N.; Biggs, M. S.

    1978-01-01

    A highly reflective hyperpure ( 25 ppm ion impurities) slip cast fused silica heat shield material developed for planetary entry probes was successfully scaled up. Process development activities for slip casting large parts included green strength improvements, casting slip preparation, aggregate casting, strength, reflectance, and subscale fabrication. Successful fabrication of a one-half scale Saturn probe (shape and size) heat shield was accomplished while maintaining the silica high purity and reflectance through the scale-up process. However, stress analysis of this original aggregate slip cast material indicated a small margin of safety (MS. = +4%) using a factor of safety of 1.25. An alternate hyperpure material formulation to increase the strength and toughness for a greater safety margin was evaluated. The alternate material incorporates short hyperpure silica fibers into the casting slip. The best formulation evaluated has a 50% by weight fiber addition resulting in an 80% increase in flexural strength and a 170% increase in toughness over the original aggregate slip cast materials with comparable reflectance.

  9. Luminescence of Yb3+ ions in silica-based glasses synthesized by SPCVD

    NASA Astrophysics Data System (ADS)

    Savel'ev, E. A.; Krivovichev, A. V.; Yapaskurt, V. O.; Golant, K. M.

    2017-02-01

    The spectra and decay kinetics of Yb3+ single-ion and cooperative luminescence in silica-based optical slab waveguides are investigated. The slab waveguides with a high content of Yb and various amounts of P and Al additives to the light-guiding core glass were fabricated on the basis of fused and unfused glassy layers synthesized via surface-plasma chemical vapor deposition (SPCVD). Luminescence was pumped by laser diodes at ∼904 nm and ∼967 nm wavelengths and recorded in the 450-1175 nm spectral band. For the pure silica host doped with Yb, only the influence of cluster sizes on the luminescence decay kinetics is determined. It is found that the profusion of deposited glass with increased Al content favors separation by geometry of the Yb3+ and Tm3+ ions; the latter are present in the glass as an uncontrollable contamination. Evidence was found that at least two different types of Yb clusters were formed in P doped silica as a result of profusion.

  10. Physicochemical evaluation of silica-glass fiber reinforced polymers for prosthodontic applications.

    PubMed

    Meriç, Gökçe; Dahl, Jon E; Ruyter, I Eystein

    2005-06-01

    This investigation was designed to formulate silica-glass fiber reinforced polymeric materials. Fused silica-glass fibers were chosen for the study. They were heat-treated at various temperatures (500 degrees C, 800 degrees C and 1100 degrees C), silanized, sized and incorporated in two modified resin mixtures (A and B). The flexural properties in dry and wet conditions were tested and statistically analyzed, and the content of residual methyl methacrylate (MMA) monomer, dimensional changes with temperature, water sorption and solubility were determined. Woven fibers [36.9% (wt/wt)], heat-treated at 500 degrees C, gave the highest strength values for the polymeric composites (an ultimate transverse strength of 200 Mpa and a flexural modulus of 10 GPa) compared with the fibers heat-treated at other temperatures. There was no statistically significant difference in the measured flexural properties between resins A and B regarding fiber treatment and water storage time. These fiber composites had a small quantity of residual MMA content [0.37 +/- 0.007% (wt/wt)] and very low water solubility, indicating good biocompatibility. It was suggested that silica-glass fibers could be used for reinforcement as a result of their anticipated good qualities in aqueous environments, such as the oral environment.

  11. Anisotropic Shape Changes of Silica Nanoparticles Induced in Liquid with Scanning Transmission Electron Microscopy.

    PubMed

    Zečević, Jovana; Hermannsdörfer, Justus; Schuh, Tobias; de Jong, Krijn P; de Jonge, Niels

    2017-01-01

    Liquid-phase transmission electron microscopy (TEM) is used for in-situ imaging of nanoscale processes taking place in liquid, such as the evolution of nanoparticles during synthesis or structural changes of nanomaterials in liquid environment. Here, it is shown that the focused electron beam of scanning TEM (STEM) brings about the dissolution of silica nanoparticles in water by a gradual reduction of their sizes, and that silica redeposites at the sides of the nanoparticles in the scanning direction of the electron beam, such that elongated nanoparticles are formed. Nanoparticles with an elongation in a different direction are obtained simply by changing the scan direction. Material is expelled from the center of the nanoparticles at higher electron dose, leading to the formation of doughnut-shaped objects. Nanoparticles assembled in an aggregate gradually fuse, and the electron beam exposed section of the aggregate reduces in size and is elongated. Under TEM conditions with a stationary electron beam, the nanoparticles dissolve but do not elongate. The observed phenomena are important to consider when conducting liquid-phase STEM experiments on silica-based materials and may find future application for controlled anisotropic manipulation of the size and the shape of nanoparticles in liquid.

  12. Heteroleptic Tetrapyrrole-Fused Dimeric and Trimeric Skeletons with Unusual Non-Frustrated Fluorescence.

    PubMed

    Zhang, Yuehong; Oh, Juwon; Wang, Kang; Chen, Chao; Cao, Wei; Park, Kyu Hyung; Kim, Dongho; Jiang, Jianzhuang

    2016-03-18

    Phthalocyanine (Pc) and porphyrin (Por) chromophores have been fused through the benzo[α]pyrazine moiety, resulting in unprecedented heteroleptic tetrapyrrole-fused dimers and trimers. The heteroleptic tetrapyrrole nature has been clearly revealed based on single-crystal X-ray diffraction analysis of the zinc dimer. Electrochemical analysis, theoretical calculations, and time-resolved spectroscopic results disclose that the two/three-tetrapyrrole-fused skeletons behave as one totally π-conjugated system as a result of the strong conjugative interaction between/among the tetrapyrrole chromophores. In particular, the effectively extended π-electron system through the fused-bridge induced strong electronic communication between the Pc and Por moieties and large transition dipole moments in the Pc-Por-fused systems, providing high fluorescence quantum yields (>0.13) and relatively long excited state lifetimes (>1.3 ns) in comparison with their homo-tetrapyrrole-fused analogues.

  13. Seismic design or retrofit of buildings with metallic structural fuses by the damage-reduction spectrum

    NASA Astrophysics Data System (ADS)

    Li, Gang; Jiang, Yi; Zhang, Shuchuan; Zeng, Yan; Li, Qiang

    2015-03-01

    Recently, the structural fuse has become an important issue in the field of earthquake engineering. Due to the trilinearity of the pushover curve of buildings with metallic structural fuses, the mechanism of the structural fuse is investigated through the ductility equation of a single-degree-of-freedom system, and the corresponding damage-reduction spectrum is proposed to design and retrofit buildings. Furthermore, the controlling parameters, the stiffness ratio between the main frame and structural fuse and the ductility factor of the main frame, are parametrically studied, and it is shown that the structural fuse concept can be achieved by specific combinations of the controlling parameters based on the proposed damage-reduction spectrum. Finally, a design example and a retrofit example, variations of real engineering projects after the 2008 Wenchuan earthquake, are provided to demonstrate the effectiveness of the proposed design procedures using buckling restrained braces as the structural fuses.

  14. Moisture Transport in Silica Gel Particle Beds: I. Theoretical Study

    SciTech Connect

    Pesaran, A. A.; Mills, A. F.

    1986-08-01

    Diffusion mechanisms of moisture within silica gel particles are investigated. It is found that for microporous silica gel surface diffusion is the dominant mechanism of moisture transport, while for macroporous silica gel both Knudsen and surface diffusion are important.

  15. Electrode potentials of tungsten in fused alkali chlorides

    NASA Astrophysics Data System (ADS)

    Ivanov, A. B.; Volkovich, V. A.; Poskryakov, D. A.; Vasin, B. D.; Griffiths, T. R.

    2016-09-01

    Anodic dissolution of tungsten was studied at 823-1173 K in the melts based on NaCl-CsCl, NaCl-KCl-CsCl and LiCl-KCl-CsCl eutectic mixtures. The process results in the formation of W(IV) ions. Prolonged contact with silica results in oxidation W(IV) ions and decreasing tungsten concentration in the electrolyte due to formation of volatile higher oxidation state chloro- and oxychloro-species. Tungsten electrode potentials were measured in NaCl-CsCl and NaCl-KCl-CsCl based melts using potentiometry.

  16. FUSE Observations of Comet C/2001 Q4 (NEAT)

    NASA Astrophysics Data System (ADS)

    Feldman, P. D.; Weaver, H. A.; Christian, D.; Combi, M. R.; Krasnopolsky, V.; Lisse, C. M.; Mumma, M. J.; Shemansky, D. E.; Stern, S. A.

    2004-11-01

    We report observations of comet C/2001 Q4 (NEAT) with the Far Ultraviolet Spectroscopic Explorer (FUSE) beginning 00:40 UT on 2004 April 24. This was the first moving target observation made by FUSE since the failure of two reaction wheels in December 2001. Spectra were obtained in the 905--1180 Å range at 0.3 Å spectral resolution using the 30'' × 30'' aperture and closely resemble the spectra of three comets observed in 2001 and reported previously. The principal features are the (0,0) bands of the CO Birge-Hopfield systems, atomic lines of \\ion{O}{1} and \\ion{H}{1}, and three lines of the H2 Lyman pumped by solar Lyman-β fluorescence. The CO C - X (0,0) band showed a nearly sinusoidal variation over the 27 hr observation interval with a period of 17.0 hr and a peak to minimum ratio of 1.56. The derived average CO production rate is Q(CO) = 8 × 1027 molecules s-1 which is about 4% that of H2O based on concurrent HST/STIS observations of OH emission. As in the previous observations, only upper limits are found for emission from \\ion{Ar}{1} and N2. A relatively strong feature near 1031.8 Å is most likely the H2 Werner (1,1) Q3 line pumped by solar \\ion{O}{6} and \\ion{N}{3}, as the corresponding lines in the (1,3) and (1,4) bands are also present. There may be evidence for weak \\ion{O}{6} emission at 1031.9 Å, in the wing of the H2 line, and at 1037.6 Å. The roughly two dozen other emissions that were not identified in the earlier spectra are also present in C/2001 Q4 at comparable strength to those in comet C/2001 A2 (LINEAR). As C/2001 A2 had a comparable water production rate to that of C/2001 Q4 at the time of observation, the source(s) of these emissions may be ubiquitous in comets. This work is based on data obtained by the NASA-CNES-CSA FUSE mission operated by The Johns Hopkins University. Financial support was partly provided by NASA contract NAS5-32985.

  17. Very strong photoluminescence emission from GaN grown on amorphous silica substrate by gas source MBE

    NASA Astrophysics Data System (ADS)

    Asahi, H.; Iwata, K.; Tampo, H.; Kuroiwa, R.; Hiroki, M.; Asami, K.; Nakamura, S.; Gonda, S.

    1999-05-01

    Polycrystalline GaN layers showing very strong photoluminescence (PL) intensities are successfully grown on amorphous fused silica (SiO 2) substrates by gas source molecular beam epitaxy (MBE) using an ion removed electron cyclotron resonance radical cell. The PL intensity is larger than that of undoped single crystalline GaN grown on sapphire by gas source MBE and is comparable to that of Si-doped single crystalline GaN grown on sapphire by metalorganic vapor-phase epitaxy at Nichia Chemical. The PL peak emission is considered to be excitonic. Undoped GaN layers grown on silica substrates exhibit n-type conduction and both n- and p-type conductions are achieved by impurity doping. These results open up the area of "Polycrystalline Semiconductor Photonics".

  18. The canister around the FUSE satellite is removed on the pad at CCAS.

    NASA Technical Reports Server (NTRS)

    1999-01-01

    At Launch Pad 17A, Cape Canaveral Air Station (CCAS), workers remove another section of the canister surrounding NASA's Far Ultraviolet Spectroscopic Explorer (FUSE) satellite. FUSE is designed to scour the cosmos for the fossil record of the origins of the universe hydrogen and deuterium. Scientists will use FUSE to study hydrogen and deuterium to unlock the secrets of how the primordial chemical elements of which all stars, planets and life evolved, were created and distributed since the birth of the universe. FUSE is scheduled to be launched from CCAS June 23 aboard a Boeing Delta II rocket.

  19. The canister around the FUSE satellite is removed on the pad at CCAS.

    NASA Technical Reports Server (NTRS)

    1999-01-01

    At Launch Pad 17A, Cape Canaveral Air Station (CCAS), workers look over NASA's Far Ultraviolet Spectroscopic Explorer (FUSE) satellite after sections of the canister have been removed. FUSE is scheduled to be launched from CCAS June 23 aboard a Boeing Delta II rocket. FUSE is designed to scour the cosmos for the fossil record of the origins of the universe hydrogen and deuterium. Scientists will use FUSE to study hydrogen and deuterium to unlock the secrets of how the primordial chemical elements of which all stars, planets and life evolved, were created and distributed since the birth of the universe.

  20. The canister around the FUSE satellite is removed on the pad at CCAS.

    NASA Technical Reports Server (NTRS)

    1999-01-01

    At Launch Pad 17A, Cape Canaveral Air Station (CCAS), workers begin to remove the canister around the top of the NASA's Far Ultraviolet Spectroscopic Explorer (FUSE) satellite. FUSE is designed to scour the cosmos for the fossil record of the origins of the universe hydrogen and deuterium. Scientists will use FUSE to study hydrogen and deuterium to unlock the secrets of how the primordial chemical elements of which all stars, planets and life evolved, were created and distributed since the birth of the universe. FUSE is scheduled to be launched from CCAS June 23 aboard a Boeing Delta II rocket.