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Sample records for aperture fused silica

  1. Pattern transfer on fused silica samples using sub-aperture reactive ion beam etching

    Energy Technology Data Exchange (ETDEWEB)

    Miessler, Andre; Arnold, Thomas [Leibniz-Institut fuer Oberflaechenmodifizierung (IOM), Permoserstrasse 15, D-04318 Leipzig (Germany)

    2012-07-01

    In comparison to sole Ar ion beam sputtering Reactive Ion Beam Etching (RIBE) reveals the main advantage of increasing the selectivity for different kind of materials due to chemical contributions during the material removal. Therefore RIBE is qualified to be an excellent candidate for pattern transfer applications. The goal of the present study is to apply a sub-aperture reactive ion beam for pattern transfer on large fused silica samples. Concerning this matter, the etching behavior in the ion beam periphery plays a decisive role. Using a Kaufman-typed ion source with NF{sub 3} as reactive gas, XPS measurements of the modified surface exposes impurities like Ni, Fe and Cr, which belongs to chemically eroded material of the plasma pot and a layer formation of silicon nitride, handicaps the etching process mainly in the beam periphery where the sputtering contribution decrease. These side effects influence the pattern transfer of trench structures, produced in AZ MIR 701 photoresist by lithography on a 2'' fused silica plate, by changing the selectivity due to modified chemical reactions of the resist layer. Concerning this we investigate a RF-Ion source for sub aperture reactive ion beam applications and finally we examine the pattern transfer on large fused silica plates using NF{sub 3}-sub-aperture RIBE.

  2. Laser-Induced Damage Growth on Larger-Aperture Fused Silica Optical Components at 351 nm

    International Nuclear Information System (INIS)

    Wan-Qing, Huang; Wei, Han; Fang, Wang; Yong, Xiang; Fu-Quan, Li; Bin, Feng; Feng, Jing; Xiao-Feng, Wei; Wan-Guo, Zheng; Xiao-Min, Zhang

    2009-01-01

    Laser-induced damage is a key lifetime limiter for optics in high-power laser facility. Damage initiation and growth under 351 nm high-fluence laser irradiation are observed on larger-aperture fused silica optics. The input surface of one fused silica component is damaged most severely and an explanation is presented. Obscurations and the area of a scratch on it are found to grow exponentially with the shot number. The area of damage site grows linearly. Micrographs of damage sites support the micro-explosion damage model which could be used to qualitatively explain the phenomena

  3. Investigation of fused silica dynamic behaviour

    International Nuclear Information System (INIS)

    Malaise, F.; Chevalier, J.M.; Bertron, I.; Malka, F.

    2006-01-01

    The survivability of the fused silica shields to shrapnel impacts is a key factor for the affordable operation of the intense laser irradiation future facility Laser Mega Joule (LMJ). This paper presents experimental data and computational modelling for LMJ fused silica upon shock wave loading and unloading. Gas-gun flyer plate impact and explosively driven tests have been conducted to investigate the dynamic behaviour of this material. Hugoniot states and the Hugoniot Elastic Limit of LMJ fused silica have been obtained. These experimental data are useful for determining some constitutive model constants of the 'Crack-Model', a continuum tensile and compressive failure model with friction based. This model has been improved by taking into account nonlinear elasticity. The numerical results obtained by performing computations of the previous tests and some ballistic impact tests are discussed. The numerical comparisons with the experimental data show good agreement. Further developments to simulate the permanent densification and the solid-to-solid phase transformation of fused silica are required. (authors)

  4. Three-dimensional printing of transparent fused silica glass

    Science.gov (United States)

    Kotz, Frederik; Arnold, Karl; Bauer, Werner; Schild, Dieter; Keller, Nico; Sachsenheimer, Kai; Nargang, Tobias M.; Richter, Christiane; Helmer, Dorothea; Rapp, Bastian E.

    2017-04-01

    Glass is one of the most important high-performance materials used for scientific research, in industry and in society, mainly owing to its unmatched optical transparency, outstanding mechanical, chemical and thermal resistance as well as its thermal and electrical insulating properties. However, glasses and especially high-purity glasses such as fused silica glass are notoriously difficult to shape, requiring high-temperature melting and casting processes for macroscopic objects or hazardous chemicals for microscopic features. These drawbacks have made glasses inaccessible to modern manufacturing technologies such as three-dimensional printing (3D printing). Using a casting nanocomposite, here we create transparent fused silica glass components using stereolithography 3D printers at resolutions of a few tens of micrometres. The process uses a photocurable silica nanocomposite that is 3D printed and converted to high-quality fused silica glass via heat treatment. The printed fused silica glass is non-porous, with the optical transparency of commercial fused silica glass, and has a smooth surface with a roughness of a few nanometres. By doping with metal salts, coloured glasses can be created. This work widens the choice of materials for 3D printing, enabling the creation of arbitrary macro- and microstructures in fused silica glass for many applications in both industry and academia.

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

    Science.gov (United States)

    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

  6. Process for manufacturing hollow fused-silica insulator cylinder

    Science.gov (United States)

    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.

  7. HVI Ballistic Limit Characterization of Fused Silica Thermal Panes

    Science.gov (United States)

    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.

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

    International Nuclear Information System (INIS)

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

    2014-01-01

    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 × 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

  9. Non-destructive evaluation of UV pulse laser-induced damage performance of fused silica optics.

    Science.gov (United States)

    Huang, Jin; Wang, Fengrui; Liu, Hongjie; Geng, Feng; Jiang, Xiaodong; Sun, Laixi; Ye, Xin; Li, Qingzhi; Wu, Weidong; Zheng, Wanguo; Sun, Dunlu

    2017-11-24

    The surface laser damage performance of fused silica optics is related to the distribution of surface defects. In this study, we used chemical etching assisted by ultrasound and magnetorheological finishing to modify defect distribution in a fused silica surface, resulting in fused silica samples with different laser damage performance. Non-destructive test methods such as UV laser-induced fluorescence imaging and photo-thermal deflection were used to characterize the surface defects that contribute to the absorption of UV laser radiation. Our results indicate that the two methods can quantitatively distinguish differences in the distribution of absorptive defects in fused silica samples subjected to different post-processing steps. The percentage of fluorescence defects and the weak absorption coefficient were strongly related to the damage threshold and damage density of fused silica optics, as confirmed by the correlation curves built from statistical analysis of experimental data. The results show that non-destructive evaluation methods such as laser-induced fluorescence and photo-thermal absorption can be effectively applied to estimate the damage performance of fused silica optics at 351 nm pulse laser radiation. This indirect evaluation method is effective for laser damage performance assessment of fused silica optics prior to utilization.

  10. Stimulated resonant scattering at stressed fused silica surface

    International Nuclear Information System (INIS)

    Bouchut, Philippe; Reymermier, Maryse

    2015-01-01

    The radiative emission in CO 2 laser heated stressed fused silica is radically modified when gold microspheres are on the surface. At high heating rates, the emission dynamics changes from thermoluminescence to stimulated resonant scattering with an emission rate that is increased tenfold and the near infrared (NIR) spectrum is red-shifted. We show that the dynamic tensile stress that rises in heated silica is coupled with a fluctuating electromagnetic field that enables electromagnetic friction between moving OH emitters from silica bulk and NIR resonant scatterers at the silica surface. (paper)

  11. Fused silica thermal conductivity dispersion at high temperature

    International Nuclear Information System (INIS)

    Bouchut, P.; Decruppe, D.; Delrive, L.

    2004-01-01

    A continuous CO 2 laser is focused to locally anneal small fused silica spots. A noncontact radiometry diagnostic enables us to follow surface temperature variation that occurs from site to site. A 'steady state' dispersion of surface temperature is observed across our sample. We show that nonhomogeneous silica thermal conductivity, above 1000 K is responsible for this temperature dispersion

  12. Enhancement of laser induced damage threshold of fused silica by acid etching combined with UV laser conditioning

    International Nuclear Information System (INIS)

    Chen Meng; Xiang Xia; Jiang Yong; Zu Xiaotao; Yuan Xiaodong; Zheng Wanguo; Wang Haijun; Li Xibin; Lu Haibing; Jiang Xiaodong; Wang Chengcheng

    2010-01-01

    Acid etching combined with UV laser conditioning is developed to enhance the laser induced damage threshold (LIDT) of fused silica. Firstly, the fused silica is etched for 1 ∼ 100 min with a buffered 1% HF solution. After acid etching, its transmittance, surface roughness and LIDT are measured. The results reveal that the fused silica has the highest LIDT and transmittance after etching for 10 min. Then UV laser (355 nm) conditioning is adopted to process the 10-min-etched fused silica. When the laser fluence is below 60% of fused silica's zero probability damage threshold, the LIDT increases gradually with the increase of laser conditioning fluence. However, the LIDT rapidly decreases to be lower than the threshold of the 10-min-etched fused silica when the conditioning fluence is up to 80% of the threshold. Proper acid etching and laser conditioning parameters will effectively enhance the laser damage resistance of fused silica. (authors)

  13. Search for stress dependence in the internal friction of fused silica

    International Nuclear Information System (INIS)

    Willems, Phil; Lamb, Corinne; Heptonstall, Alastair; Hough, Jim

    2003-01-01

    The quality factor (Q) of the vertical bounce mode of a fused silica fiber pendulum is measured at high and low stresses. The internal friction of fused silica fibers is found to be independent of stress from 12.8 to 213 MPa at a level of 1.6x10 -8 . Comparison with Q's of fiber bending modes is consistent with losses concentrated in the surface of the fiber

  14. High strength fused silica flexures manufactured by femtosecond laser

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

  16. Three-port beam splitter of a binary fused-silica grating.

    Science.gov (United States)

    Feng, Jijun; Zhou, Changhe; Wang, Bo; Zheng, Jiangjun; Jia, Wei; Cao, Hongchao; Lv, Peng

    2008-12-10

    A deep-etched polarization-independent binary fused-silica phase grating as a three-port beam splitter is designed and manufactured. The grating profile is optimized by use of the rigorous coupled-wave analysis around the 785 nm wavelength. The physical explanation of the grating is illustrated by the modal method. Simple analytical expressions of the diffraction efficiencies and modal guidelines for the three-port beam splitter grating design are given. Holographic recording technology and inductively coupled plasma etching are used to manufacture the fused-silica grating. Experimental results are in good agreement with the theoretical values.

  17. Numerical analysis of breakdown dynamics dependence on pulse width in laser-induced damage in fused silica: Role of optical system

    Science.gov (United States)

    Hamam, Kholoud A.; Gamal, Yosr E. E.-D.

    2018-06-01

    We report a numerical investigation of the breakdown and damage in fused silica caused by ultra-short laser pulses. The study based on a modified model (Gaabour et al., 2012) that solves the rate equation numerically for the electron density evolution during the laser pulse, under the combined effect of both multiphoton and electron impact ionization processes. Besides, electron loss processes due to diffusion out of the focal volume and recombination are also considered in this analysis. The model is applied to investigate the threshold intensity dependence on laser pulse width in the experimental measurements that are given by Liu et al. (2005). In this experiment, a Ti-sapphire laser source operating at 800 nm with pulse duration varies between 240 fs and 2.5 ps is used to irradiate a bulk of fused silica with dimensions 10 × 5 × 3 mm. The laser beam was focused into the bulk using two optical systems with effective numerical apertures (NA) 0.126 and 0.255 to give beam spot radius at the focus of the order 2.0 μm and 0.95 μm respectively. Reasonable agreement between the calculated thresholds and the measured ones is attained. Moreover, a study is performed to examine the respective role of the physical processes of the breakdown of fused silica in relation to the pulse width and focusing optical system. The analysis revealed a real picture of the location and size of the generated plasma.

  18. HVI Ballistic Limit Charaterization of Fused Silica Thermal Pane

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

  20. Simulation of the evolution of fused silica's surface defect during wet chemical etching

    Science.gov (United States)

    Liu, Taixiang; Yang, Ke; Li, Heyang; Yan, Lianghong; Yuan, Xiaodong; Yan, Hongwei

    2017-08-01

    Large high-power-laser facility is the basis for achieving inertial confinement fusion, one of whose missions is to make fusion energy usable in the near future. In the facility, fused silica optics plays an irreplaceable role to conduct extremely high-intensity laser to fusion capsule. But the surface defect of fused silica is a major obstacle limiting the output power of the large laser facility and likely resulting in the failure of ignition. To mitigate, or event to remove the surface defect, wet chemical etching has been developed as a practical way. However, how the surface defect evolves during wet chemical etching is still not clearly known so far. To address this problem, in this work, the three-dimensional model of surface defect is built and finite difference time domain (FDTD) method is developed to simulate the evolution of surface defect during etching. From the simulation, it is found that the surface defect will get smooth and result in the improvement of surface quality of fused silica after etching. Comparatively, surface defects (e.g. micro-crack, scratch, series of pinholes, etc.) of a typical fused silica at different etching time are experimentally measured. It can be seen that the simulation result agrees well with the result of experiment, indicating the FDTD method is valid for investigating the evolution of surface defect during etching. With the finding of FDTD simulation, one can optimize the treatment process of fused silica in practical etching or even to make the initial characterization of surface defect traceable.

  1. Mechanical losses in thin fused silica fibres

    International Nuclear Information System (INIS)

    Bilenko, I A; Braginsky, V B; Lourie, S L

    2004-01-01

    Intracavity topology of the readout system for LIGO III project and table-top QND mechanical measurements under development require the use of small probe masses and suspensions with a very low level of internal losses. A good choice is to use thin fused silica fibres similar to LIGO II mirrors suspensions. Mechanical losses of silica fibres are investigated in this work through the study of quality factor dependence on diameter for pendulum and violin modes of oscillations with diameters ranging from 1.5 to 40 μm. The estimated values of effective mechanical loss angle show noticeably greater growth with lower diameters than might be expected while extrapolating known results of research done for thicker fibres

  2. Mechanical losses in thin fused silica fibres

    Energy Technology Data Exchange (ETDEWEB)

    Bilenko, I A; Braginsky, V B; Lourie, S L [Department of Oscillatory Physics, Physics Faculty, Moscow State University (Russian Federation)

    2004-03-07

    Intracavity topology of the readout system for LIGO III project and table-top QND mechanical measurements under development require the use of small probe masses and suspensions with a very low level of internal losses. A good choice is to use thin fused silica fibres similar to LIGO II mirrors suspensions. Mechanical losses of silica fibres are investigated in this work through the study of quality factor dependence on diameter for pendulum and violin modes of oscillations with diameters ranging from 1.5 to 40 {mu}m. The estimated values of effective mechanical loss angle show noticeably greater growth with lower diameters than might be expected while extrapolating known results of research done for thicker fibres.

  3. Wideband two-port beam splitter of a binary fused-silica phase grating.

    Science.gov (United States)

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

    2008-08-01

    The usual beam splitter of multilayer-coated film with a wideband spectrum is not easy to achieve. We describe the realization of a wideband transmission two-port beam splitter based on a binary fused-silica phase grating. To achieve high efficiency and equality in the diffracted 0th and -1st orders, the grating profile parameters are optimized using rigorous coupled-wave analysis at a wavelength of 1550 nm. Holographic recording and the inductively coupled plasma dry etching technique are used to fabricate the fused-silica beam splitter grating. The measured efficiency of (45% x 2) = 90% diffracted into the both orders can be obtained with the fabricated grating under Littrow mounting. The physical mechanism of such a wideband two-port beam splitter grating can be well explained by the modal method based on two-beam interference of the modes excited by the incident wave. With the high damage threshold, low coefficient of thermal expansion, and wideband high efficiency, the presented beam splitter etched in fused silica should be a useful optical element for a variety of practical applications.

  4. Evaluation of optical properties of the amorphous carbon film on fused silica

    International Nuclear Information System (INIS)

    Baydogan, Nilguen Dogan

    2004-01-01

    Deposition was done using a pulsed filtered cathodic arc with a graphite cathode. The carbon plasma is fully ionised and condenses on the substrate, forming diamond-like material but with amorphous structure. Optical properties of amorphous carbon films on fused-silica glass were investigated and the curves of optical density have a characteristic band at approximately 950 nm. Changes of the colourimetric quantities were evaluated and compared to uncoated fused silica glass. These changes were investigated as a function of the applied substrate bias voltage using the CIE and CIELAB colour systems. It is suggested that the mechanism of absorption is related to an allowed direct transition at the amorphous carbon films on fused silica glass. The optical energy gap of the amorphous carbon film depends on the bias voltage applied to the substrate holder. The optical colour parameters and optical band gap indicated that there is a relation between the dominant wavelength of the reflectance in the visible range and the wavelength of the optical band gap

  5. Dual-function beam splitter of a subwavelength fused-silica grating.

    Science.gov (United States)

    Feng, Jijun; Zhou, Changhe; Zheng, Jiangjun; Cao, Hongchao; Lv, Peng

    2009-05-10

    We present the design and fabrication of a novel dual-function subwavelength fused-silica grating that can be used as a polarization-selective beam splitter. For TM polarization, the grating can be used as a two-port beam splitter at a wavelength of 1550 nm with a total diffraction efficiency of 98%. For TE polarization, the grating can function as a high-efficiency grating, and the diffraction efficiency of the -1st order is 95% under Littrow mounting. This dual-function grating design is based on a simplified modal method. By using the rigorous coupled-wave analysis, the optimum grating parameters can be determined. Holographic recording technology and inductively coupled plasma etching are used to manufacture the fused-silica grating. Experimental results are in agreement with the theoretical values.

  6. Optimum inductively coupled plasma etching of fused silica to remove subsurface damage layer

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Xiaolong; Liu, Ying, E-mail: liuychch@ustc.edu.cn; Liu, Zhengkun; Qiu, Keqiang; Xu, Xiangdong; Hong, Yilin; Fu, Shaojun

    2015-11-15

    Highlights: • SSD layer of fused silica is removed by ICP etch with surface roughness of 0.23 nm. • Metal contamination is successfully avoided by employing an isolation device. • Unique low-density plasma induced pitting damage is discovered and eliminated. • Lateral etching of SSD is avoided due to the improvement of etching anisotropy. - Abstract: In this work, we introduce an optimum ICP etching technique that successfully removes the subsurface damage (SSD) layer of fused silica without causing plasma induced surface damage (PISD) or lateral etching of SSD. As one of the commonest PISD initiators, metal contamination from reactor chamber is prevented by employing a simple isolation device. Based on this device, a unique low-density pitting damage is discovered and subsequently eliminated by optimizing the etching parameters. Meanwhile etching anisotropy also improves a lot, thus preventing the lateral etching of SSD. Using this proposed technique, SSD layer of fused silica is successfully removed with a surface roughness of 0.23 nm.

  7. Imaging subsurface damage of grinded fused silica optics by confocal fluorescence microscopy

    International Nuclear Information System (INIS)

    Neauport, J.; Cormont, P.; Destribats, J.; Legros, P.; Ambard, C.

    2009-01-01

    We report an experimental investigation of fluorescence confocal microscopy as a tool to measure subsurface damage on grinded fused silica optics. Confocal fluorescence microscopy was performed with an excitation at the wavelength of 405 nm on fixed abrasive diamond grinded fused silica samples. We detail the measured fluorescence spectrums and compare them to those of oil based coolants and grinding slurries. We evidence that oil based coolant used in diamond grinding induces a fluorescence that marks the subsurface damages and eases its observation. Such residual traces might also be involved in the laser damage process. (authors)

  8. Numerical analysis of breakdown dynamics dependence on pulse width in laser-induced damage in fused silica: Role of optical system

    Directory of Open Access Journals (Sweden)

    Kholoud A. Hamam

    2018-06-01

    Full Text Available We report a numerical investigation of the breakdown and damage in fused silica caused by ultra-short laser pulses. The study based on a modified model (Gaabour et al., 2012 that solves the rate equation numerically for the electron density evolution during the laser pulse, under the combined effect of both multiphoton and electron impact ionization processes. Besides, electron loss processes due to diffusion out of the focal volume and recombination are also considered in this analysis. The model is applied to investigate the threshold intensity dependence on laser pulse width in the experimental measurements that are given by Liu et al. (2005. In this experiment, a Ti-sapphire laser source operating at 800 nm with pulse duration varies between 240 fs and 2.5 ps is used to irradiate a bulk of fused silica with dimensions 10 × 5 × 3 mm. The laser beam was focused into the bulk using two optical systems with effective numerical apertures (NA 0.126 and 0.255 to give beam spot radius at the focus of the order 2.0 μm and 0.95 μm respectively. Reasonable agreement between the calculated thresholds and the measured ones is attained. Moreover, a study is performed to examine the respective role of the physical processes of the breakdown of fused silica in relation to the pulse width and focusing optical system. The analysis revealed a real picture of the location and size of the generated plasma. Keywords: Ultra-short laser pulses, Ablation mechanisms, Electron density, Electron loss processes, Avalanche ionization, Breakdown threshold

  9. Nanodrilling of fused silica using nanosecond laser radiation

    Energy Technology Data Exchange (ETDEWEB)

    Lorenz, P., E-mail: pierre.lorenz@iom-leipzig.de; Zajadacz, J.; Bayer, L.; Ehrhardt, M.; Zimmer, K.

    2015-10-01

    Graphical abstract: - Highlights: • Low-fluence irradiation of 10 nm Mo on SiO{sub 2} results in the formation of Mo droplets. • High-fluence irradiation of droplets results in the formation of holes in the SiO{sub 2}. • The process allows the formation of randomly distributed and periodic holes. • The randomly distributed hole density ρ{sub h} depends on the fluence (ρ{sub h} ≤ 1.3 μm{sup −2}). • The interaction of the laser beam with Mo/SiO{sub 2} was simulated by FEM. - Abstract: The fast laser drilling of dielectric surfaces with hole diameters in the sub-μm range and a high aspect ratio is a challenge for laser methods. In this study, a novel laser structuring method for the production of randomly and periodically distributed holes in a fused silica surface will be presented using a self-assembling process. A fused silica surface was covered with a 10 nm thick magnetron-sputtered molybdenum film. The metal film was irradiated by a KrF excimer laser (wavelength λ = 248 nm, pulse duration Δt{sub p} = 25 ns) with low laser fluences (Φ < 1 J/cm{sup 2}) and the laser-induced heating resulting in a melting of the metal film and finally in a self-assembled formation of randomly distributed metal droplets due to the surface tension of the metal liquid phase using a top hat beam profile. Furthermore, the usage of a periodically modulated laser beam profile allows the fabrication of periodically distributed droplet pattern. The multi-pulse irradiation of the laser-generated metal droplets with higher laser fluences results in a stepwise evaporation of the metal and in a partial evaporation of the fused silica near the metal droplets. Finally, the laser-induced stepwise evaporation process results in a formation of cone-like holes in the fused silica surface where the resultant holes are dependent on the size of the generated metal droplets and on the laser parameters. The “drilling” process allows the fabrication of holes with a depth up to 1

  10. Cerium-doped scintillating fused-silica fibers

    Science.gov (United States)

    Akchurin, N.; Cowden, C.; Damgov, J.; Dragoiu, C.; Dudero, P.; Faulkner, J.; Kunori, S.

    2018-04-01

    We report on a set of measurements made on (scintillating) cerium-doped fused-silica fibers using high-energy particle beams. These fibers were uniformly embedded in a copper absorber in order to utilize electromagnetic showers as a source of charged particles for generating signals. This new type of cerium-doped fiber potentially offers myriad new applications in calorimeters in high-energy physics, tracking systems, and beam monitoring detectors for future applications. The light yield, pulse shape, attenuation length, and light propagation speeds are given and discussed. Possible future applications are also explored.

  11. The size prediction of potential inclusions embedded in the sub-surface of fused silica by damage morphology

    Directory of Open Access Journals (Sweden)

    Gao Xiang

    2017-04-01

    Full Text Available A model for predicting the size ranges of different potential inclusions initiating damage on the surface of fused silica has been presented. This accounts for the heating of nanometric inclusions whose absorptivity is described based on Mie Theory. The depth profile of impurities has been measured by ICP-OES. By the measured temporal pulse profile on the surface of fused silica, the temperature and thermal stress has been calculated. Furthermore, considering the limit conditions of temperature and thermal stress strength for different damage morphologies, the size range of potential inclusions for fused silica is discussed.

  12. Ultraviolet Laser Damage Dependence on Contamination Concentration in Fused Silica Optics during Reactive Ion Etching Process

    Directory of Open Access Journals (Sweden)

    Laixi Sun

    2018-04-01

    Full Text Available The reactive ion etching (RIE process of fused silica is often accompanied by surface contamination, which seriously degrades the ultraviolet laser damage performance of the optics. In this study, we find that the contamination behavior on the fused silica surface is very sensitive to the RIE process which can be significantly optimized by changing the plasma generating conditions such as discharge mode, etchant gas and electrode material. Additionally, an optimized RIE process is proposed to thoroughly remove polishing-introduced contamination and efficiently prevent the introduction of other contamination during the etching process. The research demonstrates the feasibility of improving the damage performance of fused silica optics by using the RIE technique.

  13. High-resolution study of photoinduced modification in fused silica produced by a tightly focused femtosecond laser beam in the presence of aberrations

    International Nuclear Information System (INIS)

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

    2005-01-01

    An ultrahigh-resolution (20 nm) technique of selective chemical etching and atomic force microscopy has been used to study the photoinduced modification in fused silica produced at various depths by tightly focused femtosecond laser radiation affected by spherical aberration. We demonstrate that shapes of the irradiated zones near the threshold for modification can be predicted by taking proper account of spherical aberration caused by the refractive index mismatched air-silica interface. We establish a depth dependence of the pulse energy required to initiate modification and characterize the relationship between numerical aperture of the writing lens and practically achievable writing depth. We also show that spatial characteristics of the laser-modified zones can be controlled by a specially designed focusing system which allows correction for a variable amount of spherical aberration

  14. Influence of piezoceramic to fused silica plate thickness on the radii of curvature of piezoelectric bimorph mirror

    International Nuclear Information System (INIS)

    Libu, M.; Susanth, S.; Vasanthakumari, K. G.; Dileep Kumar, C. J.; Raghu, N.

    2012-01-01

    Piezoelectric based bimorph mirrors (PBM) find extensive use in focusing of x-ray beams. Many optical instruments require use of PBM whose radii of curvature can be tuned precisely. The 100 mm and 300 mm PBMs were fabricated with varying piezoelectric to fused silica plate thicknesses. The radii of curvature of free standing mirrors were measured as a function of voltage and it was found to decrease with increasing voltage. For a given piezoelectric plate thickness, as the fused silica thickness increases, the radii of curvature was found to increase owing to increase in stiffness of the mirror. On the other hand, for a given fused silica plate thickness, when the piezoelectric plate thickness is increased, the radii of curvature are decreased for a given electric field, due to increase in generated force. This study brings out the influence of piezoceramic to fused silica plate thickness on the radii of curvature of PBM.

  15. Deep reactive ion etching of fused silica using a single-coated soft mask layer for bio-analytical applications

    International Nuclear Information System (INIS)

    Ray, Tathagata; Zhu, Haixin; Meldrum, Deirdre R

    2010-01-01

    In this note, we present our results from process development and characterization of reactive ion etching (RIE) of fused silica using a single-coated soft masking layer (KMPR® 1025, Microchem Corporation, Newton, MA). The effects of a number of fluorine-radical-based gaseous chemistries, the gas flow rate, RF power and chamber pressure on the etch rate and etching selectivity of fused silica were studied using factorial experimental designs. RF power and pressure were found to be the most important factors in determining the etch rate. The highest fused silica etch rate obtained was about 933 Å min −1 by using SF 6 -based gas chemistry, and the highest etching selectivity between the fused silica and KMPR® 1025 was up to 1.2 using a combination of CF 4 , CHF 3 and Ar. Up to 30 µm deep microstructures have been successfully fabricated using the developed processes. The average area roughness (R a ) of the etched surface was measured and results showed it is comparable to the roughness obtained using a wet etching technique. Additionally, near-vertical sidewalls (with a taper angle up to 85°) have been obtained for the etched microstructures. The processes developed here can be applied to any application requiring fabrication of deep microstructures in fused silica with near-vertical sidewalls. To our knowledge, this is the first note on deep RIE of fused silica using a single-coated KMPR® 1025 masking layer and a non-ICP-based reactive ion etcher. (technical note)

  16. Damage and fracture in large aperture, fused silica, vacuum spatial filter lenses

    International Nuclear Information System (INIS)

    Campbell, J.H.; Edwards, G.J.; Marion, J.E.

    1995-01-01

    Optical damage that results in large scale fracture has been observed in the large, high-fluence, fused-silica, spatial filter lenses on the Nova and Beamlet lasers. In nearly all cases damage occurs on the vacuum side of the lenses and because the vacuum side of the lens is under tensile stress this damage can lead to catastrophic crack growth if the flaw (damage) size exceeds the critical flaw size for SiO 2 . The damaged 52 cm Nova lenses fracture into two and sometimes three large pieces. Although under full vacuum load at the time they fracture, the Nova lenses do not implode. Rather the authors have observed that the pieces lock together and air slowly leaks into the vacuum spatial filter housing through the lens cracks. The Beamlet lenses have a larger aspect ratio and peak tensile stress than Nova. The peak tensile stress at the center of the output surface of the Beamlet lens is 1,490 psi versus 810 psi for Nova. During a recent Beamlet high energy shot, a damage spot on the lens grew to the critical flaw size and the lens imploded. Post shot data indicate the lens probably fractured into 5 to 7 pieces, however, unlike Nova, these pieces did not lock together. Analysis shows that the likely source of damage is contamination from pinhole blow-off or out-gassing of volatile materials within the spatial filter. Contamination degrades the antireflection properties of the sol-gel coating and reduces its damage threshold. By changing the design of the Beamlet lens it may be possible to insure that it fails safe by locking up in much that same manner as the Nova lens

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

    Energy Technology Data Exchange (ETDEWEB)

    Isailovic, Slavica [Iowa State Univ., Ames, IA (United States)

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

    Science.gov (United States)

    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.

  19. Solubility of fused silica in sub- and supercritical water: Estimation from a thermodynamic model

    Czech Academy of Sciences Publication Activity Database

    Karásek, Pavel; Šťavíková, Lenka; Planeta, Josef; Hohnová, Barbora; Roth, Michal

    2013-01-01

    Roč. 83, NOV (2013), s. 72-77 ISSN 0896-8446 R&D Projects: GA ČR(CZ) GAP106/12/0522 Institutional support: RVO:68081715 Keywords : amorphous silica * fused silica * supercritical water * aqueous solubility Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 2.571, year: 2013

  20. Effects of 3D microlens transfer into fused silica substrate by CF{sub 4}/O{sub 2} dry etching

    Energy Technology Data Exchange (ETDEWEB)

    Grigaliūnas, Viktoras, E-mail: Viktoras.Grigaliunas@ktu.lt [Institute of Materials Science, Kaunas University of Technology, Barsausko 59, LT-51423 Kaunas (Lithuania); Jucius, Dalius; Lazauskas, Algirdas; Andrulevičius, Mindaugas; Sakaliūnienė, Jolita; Abakevičienė, Brigita; Kopustinskas, Vitoldas [Institute of Materials Science, Kaunas University of Technology, Barsausko 59, LT-51423 Kaunas (Lithuania); Smetona, Saulius [Qorvo, 7628 Thorndike Road Greensboro, NC 27409 United States (United States); Tamulevičius, Sigitas [Institute of Materials Science, Kaunas University of Technology, Barsausko 59, LT-51423 Kaunas (Lithuania)

    2017-01-30

    Highlights: • The etching rate of PMMA is dependent on the plasma etching time. • The etching rate ratio between PMMA and fused silica vary during plasma treatment. • The etching rate ratio variation must be assessed during the microlens design phase. - Abstract: 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 CF{sub 4}/O{sub 2} 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.

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

    Science.gov (United States)

    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.

  2. Particle damage sources for fused silica optics and their mitigation on high energy laser systems.

    Science.gov (United States)

    Bude, J; Carr, C W; Miller, P E; Parham, T; Whitman, P; Monticelli, M; Raman, R; Cross, D; Welday, B; Ravizza, F; Suratwala, T; Davis, J; Fischer, M; Hawley, R; Lee, H; Matthews, M; Norton, M; Nostrand, M; VanBlarcom, D; Sommer, S

    2017-05-15

    High energy laser systems are ultimately limited by laser-induced damage to their critical components. This is especially true of damage to critical fused silica optics, which grows rapidly upon exposure to additional laser pulses. Much progress has been made in eliminating damage precursors in as-processed fused silica optics (the advanced mitigation process, AMP3), and very high damage resistance has been demonstrated in laboratory studies. However, the full potential of these improvements has not yet been realized in actual laser systems. In this work, we explore the importance of additional damage sources-in particular, particle contamination-for fused silica optics fielded in a high-performance laser environment, the National Ignition Facility (NIF) laser system. We demonstrate that the most dangerous sources of particle contamination in a system-level environment are laser-driven particle sources. In the specific case of the NIF laser, we have identified the two important particle sources which account for nearly all the damage observed on AMP3 optics during full laser operation and present mitigations for these particle sources. Finally, with the elimination of these laser-driven particle sources, we demonstrate essentially damage free operation of AMP3 fused silica for ten large optics (a total of 12,000 cm 2 of beam area) for shots from 8.6 J/cm 2 to 9.5 J/cm 2 of 351 nm light (3 ns Gaussian pulse shapes). Potentially many other pulsed high energy laser systems have similar particle sources, and given the insight provided by this study, their identification and elimination should be possible. The mitigations demonstrated here are currently being employed for all large UV silica optics on the National Ignition Facility.

  3. Surface roughening of ground fused silica processed by atmospheric inductively coupled plasma

    International Nuclear Information System (INIS)

    Xin, Qiang; Li, Na; Wang, Jun; Wang, Bo; Li, Guo; Ding, Fei; Jin, Huiliang

    2015-01-01

    Highlights: • The morphology evolution of ground fused silica, processed by atmospheric plasma, was investigated experimentally. • The roughness development results from opening and coalescing of the plasma-etched cracks. • The shapes of grain-like etched pits are the results of the adjacent cracks coalescing with one another. • The descent of the pits density is due to some smaller etched pits that are swallowed up by larger pits. • Leading role in surface smoothing is laterally etching away the side walls of the intersecting pits. - Abstract: Subsurface damage (SSD) is a defect that is inevitably induced during mechanical processes, such as grinding and polishing. This defect dramatically reduces the mechanical strength and the laser damage thresholds of optical elements. Compared with traditional mechanical machining, atmospheric pressure plasma processing (APPP) is a relatively novel technology that induces almost no SSD during the processing of silica-based optical materials. In this paper, a form of APPP, inductively coupled plasma (ICP), is used to process fused silica substrates with fluorocarbon precursor under atmospheric pressure. The surface morphology evolution of ICP-processed substrates was observed and characterized by confocal laser scanning microscope (CLSM), field emission scanning electron microscope (SEM), and atomic force microscopy (AFM). The results show that the roughness evolves with the etching depth, and the roughness evolution is a single-peaked curve. This curve results from the opening and the coalescing of surface cracks and fractures. The coalescence procedure of these microstructures was simulated with two common etched pits on a polished fused silica surface. Understanding the roughness evolution of plasma-processed surface might be helpful in optimizing the optical fabrication chain that contains APPP

  4. Surface roughening of ground fused silica processed by atmospheric inductively coupled plasma

    Energy Technology Data Exchange (ETDEWEB)

    Xin, Qiang; Li, Na; Wang, Jun; Wang, Bo, E-mail: bradywang@hit.edu.cn; Li, Guo; Ding, Fei; Jin, Huiliang

    2015-06-30

    Highlights: • The morphology evolution of ground fused silica, processed by atmospheric plasma, was investigated experimentally. • The roughness development results from opening and coalescing of the plasma-etched cracks. • The shapes of grain-like etched pits are the results of the adjacent cracks coalescing with one another. • The descent of the pits density is due to some smaller etched pits that are swallowed up by larger pits. • Leading role in surface smoothing is laterally etching away the side walls of the intersecting pits. - Abstract: Subsurface damage (SSD) is a defect that is inevitably induced during mechanical processes, such as grinding and polishing. This defect dramatically reduces the mechanical strength and the laser damage thresholds of optical elements. Compared with traditional mechanical machining, atmospheric pressure plasma processing (APPP) is a relatively novel technology that induces almost no SSD during the processing of silica-based optical materials. In this paper, a form of APPP, inductively coupled plasma (ICP), is used to process fused silica substrates with fluorocarbon precursor under atmospheric pressure. The surface morphology evolution of ICP-processed substrates was observed and characterized by confocal laser scanning microscope (CLSM), field emission scanning electron microscope (SEM), and atomic force microscopy (AFM). The results show that the roughness evolves with the etching depth, and the roughness evolution is a single-peaked curve. This curve results from the opening and the coalescing of surface cracks and fractures. The coalescence procedure of these microstructures was simulated with two common etched pits on a polished fused silica surface. Understanding the roughness evolution of plasma-processed surface might be helpful in optimizing the optical fabrication chain that contains APPP.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  6. Characterization of deep wet etching of fused silica glass for single cell and optical sensor deposition

    International Nuclear Information System (INIS)

    Zhu, Haixin; Holl, Mark; Ray, Tathagata; Bhushan, Shivani; Meldrum, Deirdre R

    2009-01-01

    The development of a high-throughput single-cell metabolic rate monitoring system relies on the use of transparent substrate material for a single cell-trapping platform. The high optical transparency, high chemical resistance, improved surface quality and compatibility with the silicon micromachining process of fused silica make it very attractive and desirable for this application. In this paper, we report the results from the development and characterization of a hydrofluoric acid (HF) based deep wet-etch process on fused silica. The pin holes and notching defects of various single-coated masking layers during the etching are characterized and the most suitable masking materials are identified for different etch depths. The dependence of the average etch rate and surface roughness on the etch depth, impurity concentration and HF composition are also examined. The resulting undercut from the deep HF etch using various masking materials is also investigated. The developed and characterized process techniques have been successfully implemented in the fabrication of micro-well arrays for single cell trapping and sensor deposition. Up to 60 µm deep micro-wells have been etched in a fused silica substrate with over 90% process yield and repeatability. To our knowledge, such etch depth has never been achieved in a fused silica substrate by using a non-diluted HF etchant and a single-coated masking layer at room temperature

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

    Science.gov (United States)

    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.

  8. Fiber fuse light-induced continuous breakdown of silica glass optical fiber

    CERN Document Server

    Todoroki, Shin-ichi

    2014-01-01

    This book describes the fiber fuse phenomenon that causes a serious problem for the present optical communication systems. High-power light often brings about catastrophic damage to optical devices. Silica glass optical fibers with ultralow transmission loss are not the exception. A fiber fuse appears in a heated region of the fiber cable delivering a few watts of light and runs toward the light source destroying its core region. Understanding this phenomenon is a necessary first step in the development of future optical communication systems. This book provides supplementary videos and photog

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

    Energy Technology Data Exchange (ETDEWEB)

    Ficek, M.; Sobaszek, M.; Gnyba, M. [Department of Metrology and Optoelectronics, Gdansk University of Technology, 11/12G. Narutowicza St., 80-233 Gdansk (Poland); Ryl, J. [Department of Electrochemistry, Corrosion and Material Engineering, Gdansk University of Technology, 11/12 Narutowicza St., 80-233 Gdansk (Poland); Gołuński, Ł. [Department of Metrology and Optoelectronics, Gdansk University of Technology, 11/12G. Narutowicza St., 80-233 Gdansk (Poland); Smietana, M.; Jasiński, J. [Institute of Microelectronics and Optoelectronics, Warsaw University of Technology, 75 Koszykowa St., 00-662 Warsaw (Poland); Caban, P. [Institute of Electronic Materials Technology, 133 Wolczynska St., 01-919 Warsaw (Poland); Bogdanowicz, R., E-mail: rbogdan@eti.pg.gda.pl [Department of Metrology and Optoelectronics, Gdansk University of Technology, 11/12G. Narutowicza St., 80-233 Gdansk (Poland); Materials and Process Simulation Center, California Institute of Technology, Pasadena, CA 91125 (United States)

    2016-11-30

    Highlights: • Growth of 60% of transmittance diamond films with resistivity as low as 48 Ω cm. • Two step seeding process of fused silica: plasma hydrogenation and wet seeding. • Nanodiamond seeding density of 2 × 10{sup 10} cm{sup −2} at fused silica substrates. • High refractive index (2.4 @550 nm) was achieved for BDD films deposited at 500 °C. - Abstract: 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 × 10{sup 10} cm{sup −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 sp{sup 3}/sp{sup 2} 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Dmitriev, A V; Mescheriakov, S D; Mitrofanov, V P [Faculty of Physics, Moscow State University, Moscow 119991 (Russian Federation); Tokmakov, K V, E-mail: dmitriev@hbar.phys.msu.r, E-mail: mitr@hbar.phys.msu.r [Present address: Department of Physics, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom)

    2010-01-21

    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 10{sup 8}. 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.

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

    International Nuclear Information System (INIS)

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

    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 10 8 . 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.

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

    Science.gov (United States)

    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.

  13. The anomalous yield behavior of fused silica glass

    Science.gov (United States)

    Schill, W.; Heyden, S.; Conti, S.; Ortiz, M.

    2018-04-01

    We develop a critical-state model of fused silica plasticity on the basis of data mined from molecular dynamics (MD) calculations. The MD data is suggestive of an irreversible densification transition in volumetric compression resulting in permanent, or plastic, densification upon unloading. The MD data also reveals an evolution towards a critical state of constant volume under pressure-shear deformation. The trend towards constant volume is from above, when the glass is overconsolidated, or from below, when it is underconsolidated. We show that these characteristic behaviors are well-captured by a critical state model of plasticity, where the densification law for glass takes the place of the classical consolidation law of granular media and the locus of constant-volume states defines the critical-state line. A salient feature of the critical-state line of fused silica, as identified from the MD data, that renders its yield behavior anomalous is that it is strongly non-convex, owing to the existence of two well-differentiated phases at low and high pressures. We argue that this strong non-convexity of yield explains the patterning that is observed in molecular dynamics calculations of amorphous solids deforming in shear. We employ an explicit and exact rank-2 envelope construction to upscale the microscopic critical-state model to the macroscale. Remarkably, owing to the equilibrium constraint the resulting effective macroscopic behavior is still characterized by a non-convex critical-state line. Despite this lack of convexity, the effective macroscopic model is stable against microstructure formation and defines well-posed boundary-value problems.

  14. Supercritical water-treated fused silica capillaries in analytical separations: Status review

    Czech Academy of Sciences Publication Activity Database

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

    2018-01-01

    Roč. 1539, MAR (2018), s. 1-11 ISSN 0021-9673 R&D Projects: GA MV VI20172020069; GA ČR(CZ) GA16-03749S; GA MZd(CZ) NV16-29916A Institutional support: RVO:68081715 Keywords : supercritical water * fused silica capillary * surface treatment Subject RIV: CB - Analytical Chemistry, Separation OBOR OECD: Analytical chemistry Impact factor: 3.981, year: 2016

  15. Evolution of Oxygen Deficiency Center on Fused Silica Surface Irradiated by Ultraviolet Laser and Posttreatment

    Directory of Open Access Journals (Sweden)

    Hai-Bing Lü

    2014-01-01

    Full Text Available Evolution of oxygen deficiency centers (ODCs on a fused silica surface irradiated using a 355 nm ultraviolet (UV laser beam in both vacuum and atmospheric conditions was quantitatively studied using photoluminescence and X-ray photoelectron spectroscopy. When the fusedsilica surface was exposed to the UV laser in vacuum, the laser damage threshold was decreased whereas the concentration of the ODCs was increased. For the fuse silica operated under the high power lasers, creation of ODCs on their surface resulted from the UV laser irradiation, and this is more severe in a high vacuum. The laser fluence and/or laser intensity have significant effects on the increase of the ODCs concentration. The ODCs can be effectively repaired using postoxygen plasma treatment and UV laser irradiation in an excessive oxygen environment. Results also demonstrated that the “gain” and “loss” of oxygen at the silica surface is a reversible and dynamic process.

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

    Energy Technology Data Exchange (ETDEWEB)

    Bukharin, M.A. [Moscow Institute of Physics and Technology, Moscow Region (Russian Federation); Optosystems Ltd., Troitsk, Moscow (Russian Federation); Khudyakov, D.V. [Optosystems Ltd., Troitsk, Moscow (Russian Federation); Physics Instrumentation Center of the General Physics Institute, Troitsk, Moscow (Russian Federation); Vartapetov, S.K. [Physics Instrumentation Center of the General Physics Institute, Troitsk, Moscow (Russian Federation)

    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 x 10{sup -3} up to 6.5 x 10{sup -3} in fused silica and from -6 x 10{sup -3} to -9 x 10{sup -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 x 10{sup -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. (orig.)

  17. Etching of fused silica fiber by metallic laser-induced backside wet etching technique

    Energy Technology Data Exchange (ETDEWEB)

    Vass, Cs., E-mail: vasscsaba@physx.u-szeged.hu [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dóm tér 9 (Hungary); Kiss, B.; Kopniczky, J.; Hopp, B. [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dóm tér 9 (Hungary)

    2013-08-01

    The tip of multimode fused silica fiber (core diameter: 550 μm) was etched by metallic laser-induced backside wet etching (M-LIBWE) method. Frequency doubled, Q-switched Nd:YAG laser (λ = 532 nm; τ{sub FWHM} = 8 ns) was used as laser source. The laser beam was coupled into the fiber by a fused silica lens with a focal length of 1500 mm. The other tip of the fiber was dipped into liquid gallium metallic absorber. The etching threshold fluence was measured to be 475 mJ/cm{sup 2}, while the highest fluence, which resulted etching without breaking the fiber, was 1060 mJ/cm{sup 2}. The progress of etching was followed by optical microscopy, and the etch rate was measured to be between 20 and 37 nm/pulse depending on the applied laser energy. The surface morphologies of the etched tips were studied by scanning electron microscopy. A possible application of the structured fibers was also tested.

  18. Etching of fused silica fiber by metallic laser-induced backside wet etching technique

    International Nuclear Information System (INIS)

    Vass, Cs.; Kiss, B.; Kopniczky, J.; Hopp, B.

    2013-01-01

    The tip of multimode fused silica fiber (core diameter: 550 μm) was etched by metallic laser-induced backside wet etching (M-LIBWE) method. Frequency doubled, Q-switched Nd:YAG laser (λ = 532 nm; τ FWHM = 8 ns) was used as laser source. The laser beam was coupled into the fiber by a fused silica lens with a focal length of 1500 mm. The other tip of the fiber was dipped into liquid gallium metallic absorber. The etching threshold fluence was measured to be 475 mJ/cm 2 , while the highest fluence, which resulted etching without breaking the fiber, was 1060 mJ/cm 2 . The progress of etching was followed by optical microscopy, and the etch rate was measured to be between 20 and 37 nm/pulse depending on the applied laser energy. The surface morphologies of the etched tips were studied by scanning electron microscopy. A possible application of the structured fibers was also tested.

  19. Stable TEM00-mode Nd:YAG solar laser operation by a twisted fused silica light-guide

    Science.gov (United States)

    Bouadjemine, R.; Liang, D.; Almeida, J.; Mehellou, S.; Vistas, C. R.; Kellou, A.; Guillot, E.

    2017-12-01

    To improve the output beam stability of a TEM00-mode solar-pumped laser, a twisted fused silica light-guide was used to achieve uniform pumping along a 3 mm diameter and 50 mm length Nd:YAG rod. The concentrated solar power at the focal spot of a primary parabolic mirror with 1.18 m2 effective collection area was efficiently coupled to the entrance aperture of a 2D-CPC/2V-shaped pump cavity, within which the thin laser rod was pumped. Optimum solar laser design parameters were found through ZEMAX© non-sequential ray-tracing and LASCAD© laser cavity analysis codes. 2.3 W continuous-wave TEM00-mode 1064 nm laser power was measured, corresponding to 1.96 W/m2 collection efficiency and 2.2 W laser beam brightness figure of merit. Excellent TEM00-mode laser beam profile at M2 ≤ 1.05 and very good output power stability of less than 1.6% were achieved. Heliostat orientation error dependent laser power variation was considerably less than previous solar laser pumping schemes.

  20. Thermal conductivity contrast measurement of Fused Silica exposed to low-energy femtosecond laser pulses

    NARCIS (Netherlands)

    Bellouard, Y.J.; Dugan, M.; Said, A.A.; Bado, P.

    2006-01-01

    Femtosecond laser irradiation has various noticeable effects on fused silica. Of particular interest, pulses with energy levels below the ablation threshold can locally increase the refractive index and the material etching selectivity to hydrofluoric acid. The mechanism responsible for these

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Science.gov (United States)

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

    2008-11-01

    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 C 18H 38 between 350 and 400 °C, isotopic exchanges between C 18H 38 and D 2O and between C 19D 40 and H 2O 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

  3. Measurements of effective noise temperature in fused silica fiber violin modes

    Energy Technology Data Exchange (ETDEWEB)

    Bilenko, I.A.; Lourie, S.L

    2002-11-25

    The results of measurements of the effective noise temperature in fused silica fiber violin modes are presented. In these measurements the fibers were stressed and value of the effective noise temperature was obtained by direct observation of oscillations in the fundamental violin modes of several samples. Measured values indicate that effective noise temperature does not exceed the room temperature significantly. This result is important for the design of the advanced gravitational wave antennae.

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

    International Nuclear Information System (INIS)

    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 (≤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

  5. Ab initio modeling of fused silica, crystal quartz, and water Raman spectra

    Czech Academy of Sciences Publication Activity Database

    Dračínský, Martin; Benda, Ladislav; Bouř, Petr

    2011-01-01

    Roč. 512, č. 13 (2011), s. 54-59 ISSN 0009-2614 R&D Projects: GA ČR GAP208/11/0105; GA MŠk(CZ) LH11033 Grant - others:GA MŠk(CZ) 2B08021 Program:2B Institutional research plan: CEZ:AV0Z40550506 Keywords : fused silica * Raman spectroscopy * Car -Parrinello molecular dynamics Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.337, year: 2011

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  7. Fabrication of Through via Holes in Ultra-Thin Fused Silica Wafers for Microwave and Millimeter-Wave Applications

    Directory of Open Access Journals (Sweden)

    Xiao Li

    2018-03-01

    Full Text Available Through via holes in fused silica are a key infrastructure element of microwave and millimeter-wave circuits and 3D integration. In this work, etching through via holes in ultra-thin fused silica wafers using deep reactive-ion etching (DRIE and laser ablation was developed and analyzed. The experimental setup and process parameters for both methods are presented and compared. For DRIE, three types of mask materials including KMPR 1035 (Nippon Kayaku, Tokyo, Japan photoresist, amorphous silicon and chromium—with their corresponding optimized processing recipes—were tested, aiming at etching through a 100 μm fused silica wafer. From the experiments, we concluded that using chromium as the masking material is the best choice when using DRIE. However, we found that the laser ablation method with a laser pulse fluence of 2.89 J/cm2 and a pulse overlap of 91% has advantages over DRIE. The laser ablation method has a simpler process complexity, while offering a fair etching result. In particular, the sidewall profile angle is measured to be 75° to the bottom surface of the wafer, which is ideal for the subsequent metallization process. As a demonstration, a two-inch wafer with 624 via holes was processed using both technologies, and the laser ablation method showed better efficiency compared to DRIE.

  8. Large-area uniform periodic microstructures on fused silica induced by surface phonon polaritons and incident laser

    Science.gov (United States)

    Zhang, Chuanchao; Liao, Wei; Zhang, Lijuan; Jiang, Xiaolong; Chen, Jing; Wang, Haijun; Luan, Xiaoyu; Yuan, Xiaodong

    2018-06-01

    A simple and convenient means to self-organize large-area uniform periodic microstructures on fused silica by using multiple raster scans of microsecond CO2 laser pulses with beam spot overlapping at normal incidence is presented, which is based on laser-induced periodic surface structures (LIPSS) attributed to the interference between surface phonon polaritons and incident CO2 laser. The evolution of fused silica surface morphologies with increasing raster scans indicates that the period of microstructures changed from 10.6 μm to 9 μm and the profiles of microstructures changed from a sinusoidal curve to a half-sinusoidal shape. Numerical simulation results suggest that the formation of the half-sinusoidal profile is due to the exponential relationship between evaporation rate and surface temperature inducing by the intensive interference between surface phonon polaritons and incident laser. The fabricated uniform periodic microstructures show excellent structural color effect in both forward-diffraction and back-diffraction.

  9. Structural changes in irreversibly densified fused silica: implications for the chemical resistance of high level nuclear waste glasses

    International Nuclear Information System (INIS)

    Susman, S.; Volin, K.J.; Liebermann, R.C.; Gwanmesia, G.D.; Yanbin Wang

    1990-01-01

    Energetic photons and energetic particles create changes in the structure of nuclear waste glasses. These can be observed as changes in the average bulk physical properties. For example, exposure of fused silica to high doses of neutron bombardment leads to a maximum average compaction of 3%. However, this does not reveal the true extent of the densification that takes place at a microscopic level. Recent advances in high pressure technology have yielded large samples of fused silica which have been permanently densified under pressure and whose bulk density has been increased by 20%. These specimens have an overall structure that replicates the microstructure of a radiation damaged glass. Measurements have been made for the first time of the structural changes in this pressure densified vitreous silica using neutron diffraction and infrared absorption spectrometry. Extensive alterations in intermediate range order have been observed with consequent anticipated changes in chemical reactivity. The resistance of high level waste glasses to leaching by groundwater must be considered in light of these experimental findings. (author)

  10. Unified design of sinusoidal-groove fused-silica grating.

    Science.gov (United States)

    Feng, Jijun; Zhou, Changhe; Cao, Hongchao; Lu, Peng

    2010-10-20

    A general design rule of deep-etched subwavelength sinusoidal-groove fused-silica grating as a highly efficient polarization-independent or polarization-selective device is studied based on the simplified modal method, which shows that the device structure depends little on the incident wavelength, but mainly on the ratio of groove depth to incident wavelength and the ratio of wavelength to grating period. These two ratios could be used as the design guidelines for wavelength-independent structure from deep ultraviolet to far infrared. The optimized grating profile with a different function as a polarizing beam splitter, a polarization-independent two-port beam splitter, or a polarization-independent grating with high efficiency of -1st order is obtained at a wavelength of 1064 nm, and verified by using the rigorous coupled-wave analysis. The performance of the sinusoidal grating is better than a conventional rectangular one, which could be useful for practical applications.

  11. Pattern transfer on large samples using a sub-aperture reactive ion beam

    Energy Technology Data Exchange (ETDEWEB)

    Miessler, Andre; Mill, Agnes; Gerlach, Juergen W.; Arnold, Thomas [Leibniz-Institut fuer Oberflaechenmodifizierung (IOM), Permoserstrasse 15, D-04318 Leipzig (Germany)

    2011-07-01

    In comparison to sole Ar ion beam sputtering Reactive Ion Beam Etching (RIBE) reveals the main advantage of increasing the selectivity for different kind of materials due to chemical contributions during the material removal. Therefore RIBE is qualified to be an excellent candidate for pattern transfer applications. The goal of the present study is to apply a sub-aperture reactive ion beam for pattern transfer on large fused silica samples. Concerning this matter, the etching behavior in the ion beam periphery plays a decisive role. Using CF{sub 4} as reactive gas, XPS measurements of the modified surface exposes impurities like Ni, Fe and Cr, which belongs to chemically eroded material of the plasma pot as well as an accumulation of carbon (up to 40 atomic percent) in the beam periphery, respectively. The substitution of CF{sub 4} by NF{sub 3} as reactive gas reveals a lot of benefits: more stable ion beam conditions in combination with a reduction of the beam size down to a diameter of 5 mm and a reduced amount of the Ni, Fe and Cr contaminations. However, a layer formation of silicon nitride handicaps the chemical contribution of the etching process. These negative side effects influence the transfer of trench structures on quartz by changing the selectivity due to altered chemical reaction of the modified resist layer. Concerning this we investigate the pattern transfer on large fused silica plates using NF{sub 3}-sub-aperture RIBE.

  12. Near- and supercritical water as a diameter manipulation and surface roughening agent in fused silica capillaries

    Czech Academy of Sciences Publication Activity Database

    Karásek, Pavel; Planeta, Josef; Roth, Michal

    2013-01-01

    Roč. 85, č. 1 (2013), s. 327-333 ISSN 0003-2700 R&D Projects: GA ČR(CZ) GAP106/12/0522; GA ČR(CZ) GAP206/11/0138 Institutional support: RVO:68081715 Keywords : supercritical water * fused silica capillary * surface treatment Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 5.825, year: 2013

  13. Analysis of polycyclic aromatic hydrocarbons I. Determination by gas chromatography with glass and fused silica capillary columns

    International Nuclear Information System (INIS)

    Perez, M. M.; Gonzalez, D.

    1987-01-01

    A study of the analysis by gas chromatography of aromatic polycyclic hydrocarbons is presented. The separation has been carried out by glass and fused silica capillary column. The limitations and the advantages of the procedure are discussed in terms of separation efficiency, sensitivity and precision. (Author) 17 refs

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

    Energy Technology Data Exchange (ETDEWEB)

    Mishchik, K.; D' Amico, C.; Velpula, P. K.; Mauclair, C.; Boukenter, A.; Ouerdane, Y.; Stoian, R. [Laboratoire Hubert Curien, UMR 5516 CNRS, Université de Lyon, Université Jean Monnet, 42000 Saint Etienne (France)

    2013-10-07

    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 O{sub 2}{sup −} 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

  15. Incident laser modulation of a repaired damage site with a rim in fused silica rear subsurface

    Institute of Scientific and Technical Information of China (English)

    Li Li; Xiang Xia; Zu Xiao-Tao; Yuan Xiao-Dong; He Shao-Bo; Jiang Xiao-Dong; Zheng Wan-Guo

    2012-01-01

    Local CO2 laser treatment has proved to be an effective method to prevent the 351-nm laser-induced damage sitesin a fused silica surface from exponentially growing,which is responsible for limiting the lifetime of optics in high fluence laser systems.However,the CO2 laser induced ablation crater is often surrounded by a raised rim at the edge,which can also result in the intensification of transmitted ultraviolet light that may damage the downstream optics.In this work,the three-dimensional finite-difference time-domain method is developed to simulate the distribution of electrical field intensity in the vicinity of the CO2 laser mitigated damage site located in the exit subsurface of fused silica.The simulated results show that the repaired damage sites with raised rims cause more notable modulation to the incident laser than those without rims.Specifically,we present a theoretical model of using dimpled patterning to control the rim structure around the edge of repaired damage sites to avoid damage to downstream optics.The calculated results accord well with previous experimental results and the underlying physical mechanism is analysed in detail.

  16. Experimental Investigation on Cutting Characteristics in Nanometric Plunge-Cutting of BK7 and Fused Silica Glasses.

    Science.gov (United States)

    An, Qinglong; Ming, Weiwei; Chen, Ming

    2015-03-27

    Ductile cutting are most widely used in fabricating high-quality optical glass components to achieve crack-free surfaces. For ultra-precision machining of brittle glass materials, critical undeformed chip thickness (CUCT) commonly plays a pivotal role in determining the transition point from ductile cutting to brittle cutting. In this research, cutting characteristics in nanometric cutting of BK7 and fused silica glasses, including machined surface morphology, surface roughness, cutting force and specific cutting energy, were investigated with nanometric plunge-cutting experiments. The same cutting speed of 300 mm/min was used in the experiments with single-crystal diamond tool. CUCT was determined according to the mentioned cutting characteristics. The results revealed that 320 nm was found as the CUCT in BK7 cutting and 50 nm was determined as the size effect of undeformed chip thickness. A high-quality machined surface could be obtained with the undeformed chip thickness between 50 and 320 nm at ductile cutting stage. Moreover, no CUCT was identified in fused silica cutting with the current cutting conditions, and brittle-fracture mechanism was confirmed as the predominant chip-separation mode throughout the nanometric cutting operation.

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

    Science.gov (United States)

    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.

  18. Laser-induced damage of fused silica optics at 355 nm due to backward stimulated Brillouin scattering: experimental and theoretical results.

    Science.gov (United States)

    Lamaignère, Laurent; Gaudfrin, Kévin; Donval, Thierry; Natoli, Jeanyves; Sajer, Jean-Michel; Penninckx, Denis; Courchinoux, Roger; Diaz, Romain

    2018-04-30

    Forward pump pulses with nanosecond duration are able to generate an acoustic wave via electrostriction through a few centimeters of bulk silica. Part of the incident energy is then scattered back on this sound wave, creating a backward Stokes pulse. This phenomenon known as stimulated Brillouin scattering (SBS) might induce first energy-loss, variable change of the temporal waveform depending on the location in the spatial profile making accurate metrology impossible, and moreover it might also initiate front surface damage making the optics unusable. Experiments performed on thick fused silica optics at 355 nm with single longitudinal mode pulses allowed us to detect, observe and quantify these backward pulses. Experimental results are first compared to theoretical calculations in order to strengthen our confidence in metrology. On this basis a phase-modulator has been implemented on the continuous-wave seeders of the lasers leading to pulses with a wide spectrum that suppress SBS and do not exhibit temporal overshoots that also reduce Kerr effects. The developed set-ups are used to check the reduction of the backward stimulated Brillouin scattering and they allow measuring with accuracy the rear surface damage of thick fused silica optics.

  19. Fabrication of BCP/Silica Scaffolds with Dual-Pore by Combining Fused Deposition Modeling and the Particle Leaching Method

    International Nuclear Information System (INIS)

    Sa, Min-Woo; Kim, Jong Young

    2016-01-01

    In recent years, traditional scaffold fabrication techniques such as gas foaming, salt leaching, sponge replica, and freeze casting in tissue engineering have significantly limited sufficient mechanical property and cell interaction effect due to only random pores. Fused deposition modeling is the most apposite technology for fabricating the 3D scaffolds using the polymeric materials in tissue engineering application. In this study, 3D slurry mould was fabricated with a blended biphasic calcium phosphate (BCP)/Silica/Alginic acid sodium salt slurry in PCL mould and heated for two hours at 100 .deg. C to harden the blended slurry. 3D dual-pore BCP/Silica scaffold, composed of macro pores interconnected with micro pores, was successfully fabricated by sintering at furnace of 1100 .deg. C. Surface morphology and 3D shape of dual-pore BCP/Silica scaffold from scanning electron microscopy were observed. Also, the mechanical properties of 3D BCP/Silica scaffold, according to blending ratio of alginic acid sodium salt, were evaluated through compression test

  20. Fabrication of BCP/Silica Scaffolds with Dual-Pore by Combining Fused Deposition Modeling and the Particle Leaching Method

    Energy Technology Data Exchange (ETDEWEB)

    Sa, Min-Woo; Kim, Jong Young [Andong National Univ., Andong (Korea, Republic of)

    2016-10-15

    In recent years, traditional scaffold fabrication techniques such as gas foaming, salt leaching, sponge replica, and freeze casting in tissue engineering have significantly limited sufficient mechanical property and cell interaction effect due to only random pores. Fused deposition modeling is the most apposite technology for fabricating the 3D scaffolds using the polymeric materials in tissue engineering application. In this study, 3D slurry mould was fabricated with a blended biphasic calcium phosphate (BCP)/Silica/Alginic acid sodium salt slurry in PCL mould and heated for two hours at 100 .deg. C to harden the blended slurry. 3D dual-pore BCP/Silica scaffold, composed of macro pores interconnected with micro pores, was successfully fabricated by sintering at furnace of 1100 .deg. C. Surface morphology and 3D shape of dual-pore BCP/Silica scaffold from scanning electron microscopy were observed. Also, the mechanical properties of 3D BCP/Silica scaffold, according to blending ratio of alginic acid sodium salt, were evaluated through compression test.

  1. Picosecond laser damage of fused silica at 355 nm

    International Nuclear Information System (INIS)

    Meng Xiangjie; Liu Hongjie; Wang Fang; Zhang Zhen; An Xinyou; Huang Jin; Jiang Xiaodong; Wu Weidong; Ren Weiyi

    2013-01-01

    This paper studies the initiated damage threshold, the damage morphology and the subsequent damage growth on fused silica's input-surface and exit-surface under picosecond laser irradiation at 355 nm. Defects induced fluorescence on surface of the optical component is observed. The results demonstrate a significant dependence of the initiated damage on pulse duration and surface defects, and that of the damage growth on self-focusing, sub-surface defects. The damage-threshold is 3.98 J/cm 2 of input surface and 2.91 J/cm 2 of exit surface. The damage morphologies are quite different between input surface and exit surface. Slow growth behavior appears for the diameter of exit-surface and linear growth one for the depth of exit-surface in the lateral side of damage site with the increase of shot number. Defects have changed obviously compared with nanosecond laser damage in the damage area. Several main reasons such as electric intensification and self-focusing for the observed initiated damage and damage growth behavior are discussed. (authors)

  2. Fabrication and Characterization of Linear and Nonlinear Photonic Devices in Fused Silica by Femtosecond Laser Writing

    Science.gov (United States)

    Ng, Jason Clement

    Femtosecond laser processing is a flexible, three-dimensional (3D) fabrication technique used to make integrated low-loss photonic devices in fused silica. My work expanded the suite of available optical devices through the design and optimization of linear optical components such as low-loss (70-nm spectral window. My work further complemented femtosecond laser processing with the development of nonlinear device capabilities. While thermal poling is a well known process, significant challenges had restricted the development of nonlinear devices in fused silica. The laser writing process would erase the induced nonlinearity (erasing) while a written waveguide core acted as a barrier to the thermal poling process (blocking). Using second harmonic (SH) microscopy, the effectiveness of thermal poling on laser-written waveguides was systematically analyzed leading to the technique of "double poling", which effectively overcomes the two challenges of erasing and blocking. In this new process the substrate is poled before and after waveguide writing to restore the induced nonlinearity within the vicinity of the waveguide to enable effective poling for inducing a second-order nonlinearity (SON) in fused silica. A new flexible, femtosecond laser based erasure process was also developed to enable quasi-phase matching and to form arbitrarily chirped gratings. Following this result, second harmonic generation (SHG) in a quasiphase-matched (QPM) femtosecond laser written waveguide device was demonstrated. SHG in a chirped QPM structure was also demonstrated to illustrate the flexibility of the femtosecond laser writing technique. These are the first demonstration of frequency doubling in an all-femtosecond-laser-written structure. A maximum SHG conversion efficiency of 1.3 +/- 0.1x10 -11/W-cm-2 was achieved 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 SON of chi(2) = 0

  3. Growth of Laser Initiated Damage in Fused Silica at 527 nm

    International Nuclear Information System (INIS)

    Norton, M A; Donohue, E E; Hollingsworth, W G; McElroy, J N; Hackel, R P

    2003-01-01

    The effective lifetime of optics is limited by both laser-induced damage and the subsequent growth of laser initiated damage sites. We have measured the growth rate of laser-induced damage in fused silica in both air and vacuum at 527 nm. For damage on the exit surface, the data shows exponential growth in the lateral size of the damage site with shot number. The exponential growth coefficient depends linearly on the laser fluence. The behavior at the fluence threshold for growth is contrasted to that observed at 351 nm. The growth rate was not significantly affected by either the wavelength of the initiating fluence or the presence of 10 torr of air as compared to vacuum. When the damage is located on the input surface, it has both a higher threshold for growth and does not grow exponentially

  4. Plasma-Induced, Self-Masking, One-Step Approach to an Ultrabroadband Antireflective and Superhydrophilic Subwavelength Nanostructured Fused Silica Surface.

    Science.gov (United States)

    Ye, Xin; Shao, Ting; Sun, Laixi; Wu, Jingjun; Wang, Fengrui; He, Junhui; Jiang, Xiaodong; Wu, Wei-Dong; Zheng, Wanguo

    2018-04-25

    In this work, antireflective and superhydrophilic subwavelength nanostructured fused silica surfaces have been created by one-step, self-masking reactive ion etching (RIE). Bare fused silica substrates with no mask were placed in a RIE vacuum chamber, and then nanoscale fluorocarbon masks and subwavelength nanostructures (SWSs) automatically formed on these substrate after the appropriate RIE plasma process. The mechanism of plasma-induced self-masking SWS has been proposed in this paper. Plasma parameter effects on the morphology of SWS have been investigated to achieve perfect nanocone-like SWS for excellent antireflection, including process time, reactive gas, and pressure of the chamber. Optical properties, i.e., antireflection and optical scattering, were simulated by the finite difference time domain (FDTD) method. Calculated data agree well with the experiment results. The optimized SWS show ultrabroadband antireflective property (up to 99% from 500 to 1360 nm). An excellent improvement of transmission was achieved for the deep-ultraviolet (DUV) range. The proposed low-cost, highly efficient, and maskless method was applied to achieve ultrabroadband antireflective and superhydrophilic SWSs on a 100 mm optical window, which promises great potential for applications in the automotive industry, goggles, and optical devices.

  5. A study of the adsorption activities of silanol surface structures on a fused silica model substrate by combining 29Si CP MAS NMR and inverse gas chromatographic data

    NARCIS (Netherlands)

    Scholten, A.B.; Janssen, J.G.M.; Haan, de J.W.; Cramers, C.A.

    1994-01-01

    The possibilities of inverse gas-solid chromatog. (IGC) in obtaining chromatog. data on fumed silica were examd. Aerosil A-200, a fused silica model substrate in 29Si NMR anal., was trimethylsilylated to different degrees. IGC was used to vary reproducibly det. the free specific energies of

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

    International Nuclear Information System (INIS)

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

    2011-01-01

    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.

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

    Science.gov (United States)

    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.

  8. Using STED and ELSM confocal microscopy for a better knowledge of fused silica polished glass interface

    International Nuclear Information System (INIS)

    Catrin, Rodolphe; Neauport, Jerome; Taroux, Daniel; Corbineau, Thomas; Cormont, Philippe; Maunier, Cedric; Legros, Philippe

    2013-01-01

    Characteristics and nature of close surface defects existing in fused silica polished optical surfaces were explored. Samples were deliberately scratched using a modified polishing process in presence of different fluorescent dyes. Various techniques including Epi-fluorescence Laser Scanning Mode (ELSM) or Stimulated Emission Depletion (STED) confocal microscopy were used to measure and quantify scratches that are sometimes embedded under the polished layer. We show using a nondestructive technique that depth of the modified region extends far below the surface. Moreover cracks of 120 nm width can be present ten micrometers below the surface. (authors)

  9. The compaction of fused silica resulting from ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, C.M.; Ridgway, M.C. [Australian National Univ., Canberra, ACT (Australia); Leech, P.L. [Telstra Research Laboratories, Clayton, Victoria (Australia)

    1996-12-31

    Ion implantation of fused silica results in compaction and consequently an increase in refractive index. This method of modifying the near-surface region has been shown as a potential means for fabricating single mode channel waveguides. This study has measured the compaction of the implanted regions for Si implantations as a function of dose (2x10{sup 12} - 6x10{sup l6} ions/cm{sup 2}), energy (1-9 MeV) and post-implantation annealing temperature (200-900 degree C). For a given energy, a dose-dependence of the step height (depth of compacted region) is observed for doses less than {approx}10{sup 15} ions/cm{sup 2}. At higher doses the step height saturates. For a given dose, a linear trend is evident for the step height as a function of energy suggesting that the major mechanism for this compaction is electronic stopping. As the annealing temperature increases, the step height gradually decreases from {approx}0.1-0.2 {mu} to -10-20% of the original value. From the annealing data, it is possible to extract an activation energy of 0.08 eV associated with the thermal removal of the compacted region. 4 refs., 4 figs.

  10. The compaction of fused silica resulting from ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, C M; Ridgway, M C [Australian National Univ., Canberra, ACT (Australia); Leech, P L [Telstra Research Laboratories, Clayton, Victoria (Australia)

    1997-12-31

    Ion implantation of fused silica results in compaction and consequently an increase in refractive index. This method of modifying the near-surface region has been shown as a potential means for fabricating single mode channel waveguides. This study has measured the compaction of the implanted regions for Si implantations as a function of dose (2x10{sup 12} - 6x10{sup l6} ions/cm{sup 2}), energy (1-9 MeV) and post-implantation annealing temperature (200-900 degree C). For a given energy, a dose-dependence of the step height (depth of compacted region) is observed for doses less than {approx}10{sup 15} ions/cm{sup 2}. At higher doses the step height saturates. For a given dose, a linear trend is evident for the step height as a function of energy suggesting that the major mechanism for this compaction is electronic stopping. As the annealing temperature increases, the step height gradually decreases from {approx}0.1-0.2 {mu} to -10-20% of the original value. From the annealing data, it is possible to extract an activation energy of 0.08 eV associated with the thermal removal of the compacted region. 4 refs., 4 figs.

  11. Complete Procedure for Fabrication of a Fused Silica Ultrarapid Microfluidic Mixer Used in Biophysical Measurements

    Directory of Open Access Journals (Sweden)

    Dena Izadi

    2017-01-01

    Full Text Available In this paper we present a method to fabricate a fused silica microfluidic device by employing low viscosity KMPR photoresists. The resulting device is a continuous-flow microfluidic mixer based on hydrodynamic focusing. The advantages of this new fabrication method compared to the traditional approach using a poly-silicon mask are simplification, and time and cost reduction, while still preserving the quality and the performance of the mixers. This process results in devices in which the focusing channel has an aspect ratio of 10:1. The newly-fabricated mixer is successfully used to observe the folding of the Pin1 WW domain at the microsecond time scale.

  12. Probability of growth of small damage sites on the exit surface of fused silica optics.

    Science.gov (United States)

    Negres, Raluca A; Abdulla, Ghaleb M; Cross, David A; Liao, Zhi M; Carr, Christopher W

    2012-06-04

    Growth of laser damage on fused silica optical components depends on several key parameters including laser fluence, wavelength, pulse duration, and site size. Here we investigate the growth behavior of small damage sites on the exit surface of SiO₂ optics under exposure to tightly controlled laser pulses. Results demonstrate that the onset of damage growth is not governed by a threshold, but is probabilistic in nature and depends both on the current size of a damage site and the laser fluence to which it is exposed. We also develop models for use in growth prediction. In addition, we show that laser exposure history also influences the behavior of individual sites.

  13. Unified beam splitter of fused silica grating under the second Bragg incidence.

    Science.gov (United States)

    Sun, Zhumei; Zhou, Changhe; Cao, Hongchao; Wu, Jun

    2015-11-01

    A unified design for a 1×2 beam splitter of dielectric rectangular transmission gratings under the second Bragg incidence is theoretically investigated for TE- and TM-polarized light. The empirical equations of the relative grating parameters (ratio of the absolute one to incidence wavelength) for this design are also obtained with the simplified modal method (SMM). The influences of polarization of incident light and relative grating parameters on the performance of the beam splitter are thoroughly studied based on the SMM and rigorous coupled-wave analysis. Two specific gratings are demonstrated with an even split and high diffraction efficiency (>94% for TE polarization and >97% for the TM counterpart). The unified profiles of the 1×2 beam splitter are independent from the incidence wavelength since the refractive index of fused silica is roughly a constant over a wide range of wavelengths, which should be promising for future applications.

  14. Fused silica segments: a possible solution for x-ray telescopes with very high angular resolution like Lynx/XRS

    Science.gov (United States)

    Salmaso, Bianca; Basso, Stefano; Civitani, Marta; Ghigo, Mauro; Hołyszko, Joanna; Spiga, Daniele; Vecchi, Gabriele; Pareschi, Giovanni

    2017-09-01

    In order to look beyond Chandra, the Lynx/XRS mission has been proposed in USA and is currently studied by NASA. The optic will have an effective area of 2.5 m2 and an angular resolution of 0.5 arcsec HEW at 1 keV. In order to fulfill these requirements different technologies are considered, with the approaches of both full and segmented shells (that, possibly, can be also combined together). Concerning the production of segmented mirrors, a variety of thin substrates (glass, metal, silicon) are envisaged, that can be produced using both direct polishing or replication methods. Innovative post-fabrication correction methods (such as piezoelectric or magneto-restrictive film actuators on the back surface, differential deposition, ion implantation) are being also considered in order to reach the final tolerances. In this paper we are presenting a technology development based on fused silica (SiO2) segmented substrates, owing the low coefficient of thermal expansion of Fused Silica and its high chemical stability compared to other glasses. Thin SiO2 segmented substrates (typically 2 mm thick) are figured by direct polishing combined with final profile ion figuring correction, while the roughness reduction is reached with pitch tools. For the profile and roughness correction, the segments are glued to a substrate. In this paper we present the current status of this technology.

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

    Directory of Open Access Journals (Sweden)

    Sudipta Pathak

    2013-11-01

    Full Text Available 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.

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

    Science.gov (United States)

    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.

  17. Growth behavior of laser-induced damage on fused silica optics under UV, ns laser irradiation.

    Science.gov (United States)

    Negres, Raluca A; Norton, Mary A; Cross, David A; Carr, Christopher W

    2010-09-13

    The growth behavior of laser-induced damage sites is affected by a large number of laser parameters as well as site morphology. Here we investigate the effects of pulse duration on the growth rate of damage sites located on the exit surface of fused silica optics. Results demonstrate a significant dependence of the growth parameters on laser pulse duration at 351 nm from 1 ns to 15 ns, including the observation of a dominant exponential versus linear, multiple-shot growth behavior for long and short pulses, respectively. These salient behaviors are tied to the damage morphology and suggest a shift in the fundamental growth mechanisms for pulses in the 1-5 ns range.

  18. A process to fabricate fused silica nanofluidic devices with embedded electrodes using an optimized room temperature bonding technique

    Science.gov (United States)

    Boden, Seth; Karam, P.; Schmidt, A.; Pennathur, S.

    2017-05-01

    Fused silica is an ideal material for nanofluidic systems due to its extreme purity, chemical inertness, optical transparency, and native hydrophilicity. However, devices requiring embedded electrodes (e.g., for bioanalytical applications) are difficult to realize given the typical high temperature fusion bonding requirements (˜1000 °C). In this work, we optimize a two-step plasma activation process which involves an oxygen plasma treatment followed by a nitrogen plasma treatment to increase the fusion bonding strength of fused silica at room temperature. We conduct a parametric study of this treatment to investigate its effect on bonding strength, surface roughness, and microstructure morphology. We find that by including a nitrogen plasma treatment to the standard oxygen plasma activation process, the room temperature bonding strength increases by 70% (0.342 J/m2 to 0.578 J/m2). Employing this optimized process, we fabricate and characterize a nanofluidic device with an integrated and dielectrically separated electrode. Our results prove that the channels do not leak with over 1 MPa of applied pressure after a 24 h storage time, and the electrode exhibits capacitive behavior with a finite parallel resistance in the upper MΩ range for up to a 6.3Vdc bias. These data thus allow us to overcome the barrier that has barred nanofluidic progress for the last decade, namely, the development of nanometer scale well-defined channels with embedded metallic materials for far-reaching applications such as the exquisite manipulation of biomolecules.

  19. Laser-induced damage of fused silica at 355 and 1065 nm initiated at aluminum contamination particles on the surface

    International Nuclear Information System (INIS)

    Genin, F.Y.; Michlitsch, K.; Furr, J.; Kozlowski, M.R.; Krulevitch, P.

    1997-01-01

    1-μm thick circular dots, 10-250 μm dia, were deposited onto 1.14 cm thick fused silica windows by sputtering Al through a mask. Al shavings were also deposited on the windows to investigate effects of particle-substrate adhesion. The silica windows were then illuminated repetitively using a 3-ns, 355 nm and an 8.6-ns, 1064 nm laser. The tests were conducted at near normal incidence with particles on input and output surfaces of the windows. During the first shot, a plasma ignited at the metal particle and damage initiated on the fused silica surface. The morphology of the damage at the metal dots were reproducible but different for input and output surface contamination. For input surface contamination, minor damage occurred where the particle was located; such damage ceased to grow with the removal of contaminant material. More serious damage (pits and cracks) was initiated on the output surface (especially at 355 nm) and grew to catastrophic proportions after few shots. Output surface contaminants were usually ejected on the initial shot, leaving a wave pattern on the surface. No further damage occurred with subsequent shots unless a shot (usually the first shot) cracked the surface; such behavior was mostly observed at 355 nm and occasionally for large shavings at 1064 nm. The size of the damaged area scaled with the size of the particle (except when catastrophic damage occurred). Onset of catastrophic damage on output surface occurred only when particles exceeded a critical size. Damage behavior of the sputtered dots was found to be qualitatively similar to that of the shavings. The artificial contamination technique accelerated the study by allowing better control of the test conditions

  20. Constitutive law for the densification of fused silica with applications in polishing and microgrinding

    Science.gov (United States)

    Lambropoulos, John C.; Fang, Tong; Xu, Su; Gracewski, Sheryl M.

    1995-09-01

    We discuss a constitutive model describing the permanent densification of fused silica under large applied pressures and shear stresses. The constitutive law is assumed to be rate- independent, and uses a yield function coupling hydrostatic pressure and shear stress, a flow rule describing the evolution of permanent strains after initial densification, and a hardening rule describing the dependence of the incremental densification on the levels of applied stresses. The constitutive law accounts for multiaxial states of stress, since during polishing and grinding operations complex stress states occur in a thin surface layer due to the action of abrasive particles. Due to frictional and other abrasive forces, large shear stresses are present near the surface during manufacturing. We apply the constitutive law in estimating the extent of the densified layer during the mechanical interaction of an abrasive grain and a flat surface.

  1. Design of fused-silica rectangular transmission gratings for polarizing beam splitter based on modal method.

    Science.gov (United States)

    Zhao, Huajun; Yuan, Dairong

    2010-02-10

    Examples of optimal designs for a fused-silica transmitted grating with high-intensity tolerance are discussed. It has the potential of placing up to 99% incident polarized light in a single diffraction order. The modal method has been used to analyze the effective indices for TE and TM polarization propagating through the grating region, and the eigenvalue equation of the modal method is transformed to a new form. It is shown that the effective indices of the first two modes depend on the value of the period under Littrow mounting with filling factor f=0.5. The polarization properties of the polarizing beam splitter are analyzed by rigorous coupled-wave analysis (RCWA) at the wavelength of 1.064 microm. The optimal design perfectly matches the RCWA simulation result.

  2. A hybrid concept (segmented plus monolithic fused silica shells) for a high-throughput and high-angular resolution x-ray mission (Lynx/X-Ray Surveyor like)

    Science.gov (United States)

    Basso, Stefano; Civitani, Marta; Pareschi, Giovanni; Parodi, Giancarlo

    2017-09-01

    Lynx is a large area and high angular resolution X-ray mission being studied by NASA to be presented to the next Decadal Survey for the implementation in the next decade. It aims to realize an X-ray telescope with the effective area similar to Athena (2 m2 at 1 keV) but with the same angular resolution of Chandra and a much larger Field Of View (up 20 arcmin x 20 arcmin). The science of X-ray Surveyor requires a large-throughput mirror assembly with sub-arcsec angular resolution. These future X-ray mirrors have a set of requirements which, collectively, represents very substantial advances over any currently in operation or planned for missions other than X-ray Surveyor. Of particular importance is achieving low mass per unit collecting area, while maintaining Chandra like angular resolution. Among the possible solutions under study, the direct polishing of both thin monolithic pseudo-cylindrical shells and segments made of fused silica are being considered as viable solutions for the implementation of the mirrors. Fused silica has very good thermomechanical parameters (including a very low CTE), making the material particularly well suited for for the production of the Lynx mirrors. It should be noted that the use of close shells is also very attractive, since the operations for the integration of the shells will be greatly simplified and the area lost due to the vignetting from the interfacing structures minimized even if the management of such big (diameter of 3 m) and thin shells have to be demonstrated. In this paper we will discuss a possible basic layout for a full shell mirror and a hybrid concept (segmented plus monolithic shells made of fused silica) as a second solution, for the Lynx/XRS telescope, discussing preliminary results in terms of optical and mechanical performance.

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

    International Nuclear Information System (INIS)

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

    2003-01-01

    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

  4. Effect of a core-softened O-O interatomic interaction on the shock compression of fused silica

    Science.gov (United States)

    Izvekov, Sergei; Weingarten, N. Scott; Byrd, Edward F. C.

    2018-03-01

    Isotropic soft-core potentials have attracted considerable attention due to their ability to reproduce thermodynamic, dynamic, and structural anomalies observed in tetrahedral network-forming compounds such as water and silica. The aim of the present work is to assess the relevance of effective core-softening pertinent to the oxygen-oxygen interaction in silica to the thermodynamics and phase change mechanisms that occur in shock compressed fused silica. We utilize the MD simulation method with a recently published numerical interatomic potential derived from an ab initio MD simulation of liquid silica via force-matching. The resulting potential indicates an effective shoulder-like core-softening of the oxygen-oxygen repulsion. To better understand the role of the core-softening we analyze two derivative force-matching potentials in which the soft-core is replaced with a repulsive core either in the three-body potential term or in all the potential terms. Our analysis is further augmented by a comparison with several popular empirical models for silica that lack an explicit core-softening. The first outstanding feature of shock compressed glass reproduced with the soft-core models but not with the other models is that the shock compression values at pressures above 20 GPa are larger than those observed under hydrostatic compression (an anomalous shock Hugoniot densification). Our calculations indicate the occurrence of a phase transformation along the shock Hugoniot that we link to the O-O repulsion core-softening. The phase transformation is associated with a Hugoniot temperature reversal similar to that observed experimentally. With the soft-core models, the phase change is an isostructural transformation between amorphous polymorphs with no associated melting event. We further examine the nature of the structural transformation by comparing it to the Hugoniot calculations for stishovite. For stishovite, the Hugoniot exhibits temperature reversal and associated

  5. 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

    Czech Academy of Sciences Publication Activity Database

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

    2017-01-01

    Roč. 38, 9-10 (2017), s. 1260-1267 ISSN 0173-0835 R&D Projects: GA ČR(CZ) GA16-03749S; GA MZd(CZ) NV16-29916A Institutional support: RVO:68081715 Keywords : fused silica capillary * supercritical water * volume coupling electrophoresis Subject RIV: CB - Analytical Chemistry, Separation OBOR OECD: Analytical chemistry Impact factor: 2.744, year: 2016

  6. The COronal Solar Magnetism Observatory (COSMO) Large Aperture Coronagraph

    Science.gov (United States)

    Tomczyk, Steve; Gallagher, Dennis; Wu, Zhen; Zhang, Haiying; Nelson, Pete; Burkepile, Joan; Kolinksi, Don; Sutherland, Lee

    2013-04-01

    The COSMO is a facility dedicated to observing coronal and chromospheric magnetic fields. It will be located on a mountaintop in the Hawaiian Islands and will replace the current Mauna Loa Solar Observatory (MLSO). COSMO will provide unique observations of the global coronal magnetic fields and its environment to enhance the value of data collected by other observatories on the ground (e.g. SOLIS, BBO NST, Gregor, ATST, EST, Chinese Giant Solar Telescope, NLST, FASR) and in space (e.g. SDO, Hinode, SOHO, GOES, STEREO, Solar-C, Solar Probe+, Solar Orbiter). COSMO will employ a fleet of instruments to cover many aspects of measuring magnetic fields in the solar atmosphere. The dynamics and energy flow in the corona are dominated by magnetic fields. To understand the formation of CMEs, their relation to other forms of solar activity, and their progression out into the solar wind requires measurements of coronal magnetic fields. The large aperture coronagraph, the Chromospheric and Prominence Magnetometer and the K-Coronagraph form the COSMO instrument suite to measure magnetic fields and the polarization brightness of the low corona used to infer electron density. The large aperture coronagraph will employ a 1.5 meter fuse silica singlet lens, birefringent filters, and a spectropolarimeter to cover fields of view of up to 1 degree. It will observe the corona over a wide range of emission lines from 530.3 nm through 1083.0 nm allowing for magnetic field measurements over a wide range of coronal temperatures (e.g. FeXIV at 530.3 nm, Fe X at 637.4 nm, Fe XIII at 1074.7 and 1079.8 nm. These lines are faint and require the very large aperture. NCAR and NSF have provided funding to bring the large aperture coronagraph to a preliminary design review state by the end of 2013. As with all data from Mauna Loa, the data products from COSMO will be available to the community via the Mauna Loa website: http://mlso.hao.ucar.edu

  7. Birefringence profile adjustment by spatial overlap of nanogratings induced by ultra-short laser pulses inside fused silica

    Science.gov (United States)

    Arabanian, Atoosa Sadat; Najafi, Somayeh; Ajami, Aliasghar; Husinsky, Wolfgang; Massudi, Reza

    2018-02-01

    We have succeeded in realizing a method to control the spatial distribution of optical retardation as a result of nanogratings in bulk-fused silica induced by ultrashort laser pulses. A colorimetry-based retardation measurement (CBRM) based on the Michel-Levy interference color chart using a polarization microscope is used to determine the profiles of the optical retardation. Effects of the spatial overlap of written regions as well as the energy and polarization of the writing pulses on the induced retardations are studied. It has been found that the spatial overlap of lines written by pulse trains with different energies and polarizations can result in an adjustment of the induced birefringence in the overlap region. This approach offers the possibility of designing polarization-sensitive components with a desired birefringence profile.

  8. Two-photon induced fluorescence and other optical effects in irradiated and doped fused silica

    International Nuclear Information System (INIS)

    Kramer, S.D.

    1986-07-01

    The objective of this program was to assess and identify irradiation techniques which could be used to modify the optical charactistics of doped fused silica. Primary emphasis was placed on determining if gamma ray or neutron bombardment of the glass would enhance certain Raman and nonlinear optical effects. In particular, the effect of irradiation on optical two photon induced fluorescence was studied in detail. The maximum radiation exposures used were 10 6 rads (Si) of gamma rays and neutron fluences of 1 x 10 14 neutrons/cm 2 . The optical measurements were made at room temperature between one and four months after irradiation. The maximum input light intensity was 10 9 watts/cm 2 at a near infrared (1.06 μ) input wavelength which was chosen to lie in a transparent spectral region of the glass. Under these experimental conditions a careful search revealed no detectable two-photon induced fluorescence in the region from 550 to 900 nm. The upper limit for the photon efficiency of this process was determined to be less than 1 x 10 -10 %. 89 refs., 12 figs

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

    Science.gov (United States)

    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.

  10. An investigation of laser processing of silica surfaces

    International Nuclear Information System (INIS)

    Weber, A.J.; Stewart, A.F.; Exarhos, G.J.; Stowell, W.K.

    1988-01-01

    An initial set of experiments has been conducted to determine the practicality of laser processing of optical substrates. In contrast to earlier work, a high average power CO 2 laser was used to flood load the entire surface of each test sample. Fused silica substrates were laser polished on both surfaces at power densities ranging from 150 to 350 W/cm 2 . During each test sequence sample surface temperatures were recorded using a thermal imaging system. Extensive pre- and post-test characterization revealed that surface roughness and scattering of bare silica surfaces were reduced while internal stress increased. Laser damage thresholds were found to increase only for certain conditions. Changes in the microstructure were observed. These preliminary experiments demonstrate that laser processing can dramatically improve the optical properties of fused silica substrates

  11. Pre-concentration and separation of bacteria by volume coupling electrophoresis on supercritical water-etched fused silica capillary with two segments of different internal diameters and inner surface roughnesses

    Czech Academy of Sciences Publication Activity Database

    Horká, Marie; Karásek, Pavel; Roth, Michal; Růžička, F.

    2018-01-01

    Roč. 410, č. 1 (2018), s. 167-175 ISSN 1618-2642 R&D Projects: GA MV(CZ) VI20172020069; GA ČR(CZ) GA16-03749S; GA MZd(CZ) NV16-29916A Keywords : fused silica capillary * volume coupling electrophoresis * supercritical water * blood Subject RIV: CB - Analytical Chemistry , Separation OBOR OECD: Analytical chemistry Impact factor: 3.431, year: 2016

  12. Pre-concentration and separation of bacteria by volume coupling electrophoresis on supercritical water-etched fused silica capillary with two segments of different internal diameters and inner surface roughnesses

    Czech Academy of Sciences Publication Activity Database

    Horká, Marie; Karásek, Pavel; Roth, Michal; Růžička, F.

    2018-01-01

    Roč. 410, č. 1 (2018), s. 167-175 ISSN 1618-2642 R&D Projects: GA MV(CZ) VI20172020069; GA ČR(CZ) GA16-03749S; GA MZd(CZ) NV16-29916A Keywords : fused silica capillary * volume coupling electrophoresis * supercritical water * blood Subject RIV: CB - Analytical Chemistry, Separation OBOR OECD: Analytical chemistry Impact factor: 3.431, year: 2016

  13. Evidence of localized amorphous silicon clustering from Raman depth-probing of silicon nanocrystals in fused silica

    International Nuclear Information System (INIS)

    Barba, D; Martin, F; Ross, G G

    2008-01-01

    Silicon nanocrystals (Si-nc) and amorphous silicon (α-Si) produced by silicon implantation in fused silica have been studied by micro-Raman spectroscopy. Information regarding the Raman signature of the α-Si phonon excitation was extracted from Raman depth-probing measurements using the phenomenological phonon confinement model. The spectral deconvolution of the Raman measurements recorded at different laser focusing depths takes into account both the Si-nc size variation and the Si-nc spatial distribution within the sample. The phonon peak associated with α-Si around 470 cm -1 is greatest for in-sample laser focusing, indicating that the formation of amorphous silicon is more important in the region containing a high concentration of silicon excess, where large Si-nc are located. As also observed for Si-nc systems prepared by SiO x layer deposition, this result demonstrates the presence of α-Si in high excess Si implanted Si-nc systems

  14. Design of a 50/50 splitting ratio non-polarizing beam splitter based on the modal method with fused-silica transmission gratings

    Science.gov (United States)

    Zhao, Huajun; Yuan, Dairong; Ming, Hai

    2011-04-01

    The optical design of a beam splitter that has a 50/50 splitting ratio regardless of the polarization is presented. The non-polarizing beam splitter (NPBS) is based on the fused-silica rectangular transmission gratings with high intensity tolerance. The modal method has been used to estimate the effective index of the modes excited in the grating region for TE and TM polarizations. If a phase difference equals an odd multiples of π/2 for the first two modes (i.e. modes 0 and 1), the incident light will be diffracted into the 0 and -1 orders with about 50% and 50% diffraction efficiency for TM and TE polarizations, respectively.

  15. Design of a Fused-Silica Subwavelength Polarizing Beam Splitter Grating Based on the Modal Method

    International Nuclear Information System (INIS)

    Hua-Jun, Zhao; Dai-Rong, Yuan; Pei, Wang; Yong-Hua, Lu; Hai, Ming

    2010-01-01

    A polarizing beam splitter (PBS) design based on a fused-silica lamellar subwavelength transmission grating is demonstrated with the modal method, where TE- and TM-polarized waves are mainly diffracted in the −1 st and 0 th orders, respectively. The physical explanation of the grating diffraction is illustrated by the interference of the corresponding parts of the two propagating modes, which is very similar to a Mach–Zehnder interferometer. It is shown that diffraction efficients over 99% for a TM-polarized wave in the −1 st order and 90% for a TE-polarized wave in the 0 th order are obtained at the wavelength of 1.053 μm. The polarization transmission extinction ratios are better than 33 dB and 51 dB for the order 0 th and the −1 st order, respectively. The splitting properties of the PBS grating designed by the modal method are in good agreement with the results simulated by the rigorous coupled wave analysis method. (fundamental areas of phenomenology(including applications))

  16. Measurement of temperature and concentration influence on the dispersion of fused silica glass photonic crystal fiber infiltrated with water-ethanol mixture

    Science.gov (United States)

    Van, Hieu Le; Buczynski, Ryszard; Long, Van Cao; Trippenbach, Marek; Borzycki, Krzysztof; Manh, An Nguyen; Kasztelanic, Rafal

    2018-01-01

    We present experimental and simulation results of the zero-dispersion shift in photonics crystal fibers infiltrated with water-ethanol mixture. The fiber based on the fused silica glass with a hexagonal lattice consists of seven rings of air-holes filled by liquid. We show that it is possible to shift the zero-dispersion wavelength by 35 ps/nm/km when changing the temperature by 60 °C, and by 42 ps/nm/km when changing the concentration of ethanol from 0 to 100%. The results also show that for the optical fiber filed with pure ethanol the flattened part of the dispersion shifts from anomalous to the normal regime at temperatures below -70 °C.

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

    Science.gov (United States)

    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.

  18. Cavity Formation Modeling of Fiber Fuse in Single-Mode Optical Fibers

    Directory of Open Access Journals (Sweden)

    Yoshito Shuto

    2017-01-01

    Full Text Available The evolution of a fiber-fuse phenomenon in a single-mode optical fiber was studied theoretically. To clarify both the silica-glass densification and cavity formation, which have been observed in fiber fuse propagation, we investigated a nonlinear oscillation model using the Van Der Pol equation. This model was able to phenomenologically explain both the densification of the core material and the formation of periodic cavities in the core layer as a result of a relaxation oscillation.

  19. All-silica nanofluidic devices for DNA-analysis fabricated by imprint of sol-gel silica with silicon stamp

    DEFF Research Database (Denmark)

    Mikkelsen, Morten Bo Lindholm; Letailleur, Alban A; Søndergård, Elin

    2011-01-01

    We present a simple and cheap method for fabrication of silica nanofluidic devices for single-molecule studies. By imprinting sol-gel materials with a multi-level stamp comprising micro- and nanofeatures, channels of different depth are produced in a single process step. Calcination of the imprin......We present a simple and cheap method for fabrication of silica nanofluidic devices for single-molecule studies. By imprinting sol-gel materials with a multi-level stamp comprising micro- and nanofeatures, channels of different depth are produced in a single process step. Calcination...... of the imprinted hybrid sol-gel material produces purely inorganic silica, which has very low autofluorescence and can be fusion bonded to a glass lid. Compared to top-down processing of fused silica or silicon substrates, imprint of sol-gel silica enables fabrication of high-quality nanofluidic devices without...

  20. Analysis of polycyclic aromatic hydrocarbons I. Determination by gas chromatography with glass and fused silica capillary columns; Analisis de Hidrocarburos aromaticos policiclicos. I. Determinacion por cromatografia de gases con columnas capilares de vidrio de silice fundida

    Energy Technology Data Exchange (ETDEWEB)

    Perez, M M; Gonzalez, D

    1987-07-01

    A study of the analysis by gas chromatography of aromatic polycyclic hydrocarbons is presented. The separation has been carried out by glass and fused silica capillary column. The limitations and the advantages of the procedure are discussed in terms of separation efficiency, sensitivity and precision. (Author) 17 refs.

  1. Electric fuses operation, a review: 2. Arcing period

    International Nuclear Information System (INIS)

    Bussière, W

    2012-01-01

    In the electric fuse operation the arcing period follows immediately the pre-arcing period depicted in Part 1 (Part 1. Pre-arcing period). The transition between these two operation steps is not fully understood at this time. To simplify the beginning of the arcing period can be identified with the electric arc ignition i.e. with the electrodes voltage drop. The consecutive plasma is of metallic type at the beginning of the arcing period and of metallic plus silica type with varying mixture up to the end of the arcing period. The energy brought by the fault current is withdrawn by means of the interaction between the electric arc and the arc quenching material (usually silica sand) whose morphometric properties influence the properties of the plasma column: composition, thermodynamic properties and transport coefficients of the plasma column depend on the porosity (and other morphometric properties) of the filler. The fuse element erosion also known as burn-back is responsible for the lengthening of the plasma column and the variations of the electric field. The whole of these processes is depicted by means of experimental results or modellings when possible.

  2. Comparison of neutron and gamma irradiation effects on KU1 fused silica monitored by electron paramagnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Bravo, D. [Department Fisica de Materiales, Universidad Autonoma de Madrid, E-28049 Madrid (Spain)], E-mail: david.bravo@uam.es; Lagomacini, J.C. [Department Fisica de Materiales, Universidad Autonoma de Madrid, E-28049 Madrid (Spain); Leon, M.; Martin, P. [Materiales para Fusion, CIEMAT, Avda. Complutense 22, E-28040 Madrid (Spain); Martin, A. [Department Fisica e Instalaciones, ETS Arquitectura UPM, E-28040 Madrid (Spain); Lopez, F.J. [Department Fisica de Materiales, Universidad Autonoma de Madrid, E-28049 Madrid (Spain); Ibarra, A. [Materiales para Fusion, CIEMAT, Avda. Complutense 22, E-28040 Madrid (Spain)

    2009-06-15

    Electron paramagnetic resonance (EPR) studies have been carried out on KU1 fused silica irradiated with neutrons at fluences 10{sup 21} and 10{sup 22} n/m{sup 2}, and gamma-ray doses up to 12 MGy. The effects of post-irradiation thermal annealing treatments, up to 850 deg. C, have also been investigated. Paramagnetic oxygen-related defects (POR and NBOHC) and E'-type defects have been identified and their concentration has been measured as a function of neutron fluence, gamma dose and post-irradiation annealing temperature. It is found that neutrons at the highest fluence generate a much higher concentration of defects (mainly E' and POR, both at concentrations about 5 x 10{sup 18} spins/cm{sup 3}) than gamma irradiations at the highest dose (mainly E' at a concentration about 4 x 10{sup 17} spins/cm{sup 3}). Moreover, for gamma-irradiated samples a lower treatment temperature (about 400 deg. C) is required to annihilate most of the observed defects than for neutron-irradiated ones (about 600 deg. C)

  3. P2. A fused silica Cherenkov detector for the high precision determination of the weak mixing angle

    Energy Technology Data Exchange (ETDEWEB)

    Gerz, Kathrin; Becker, Dominik; Jennewein, Thomas; Baunack, Sebastian [Johannes Gutenberg Universitaet Mainz (Germany); Kumar, Krishna [Department of Physics and Astronomy, Stony Brook University, Stony Brook (United States); Maas, Frank [Johannes Gutenberg Universitaet Mainz (Germany); Helmholtz Institut Mainz (Germany)

    2016-07-01

    The weak mixing angle is a central parameter of the standard model and its high precision determination is tantamount to probing for new physics effects. The P2 experiment at the MESA accelerator in Mainz will perform such a measurement of the weak mixing angle via parity violating electron-proton scattering. We aim to determine sin{sup 2}(Θ{sub W}) to a relative precision of 0.13%. Since the weak charge of the proton is small compared to its electric charge, the measurable asymmetry is only 33 ppb, requiring a challenging measurement to a precision of only 0.44 ppb. In order to achieve this precision we need to collect very high statistics and carefully minimize interfering effects like apparatus induced false asymmetries. We present the status of the development of an integrating fused-silica Cherenkov detector, which is suitable for a high precision and high intensity experiment like P2. The contribution will focus on the investigation of the detector's response to incoming signal and background particles both by simulations and by beam tests at the MAMI accelerator.

  4. A Spectroscopic Comparison of Femtosecond Laser Modified Fused Silica using kHz and MHz Laser Systems.

    Energy Technology Data Exchange (ETDEWEB)

    Reichman, W J; Krol, D M; Shah, L; Yoshino, F; Arai, A; Eaton, S M; Herman, P R

    2005-09-29

    Waveguides were written in fused silica using both a femtosecond fiber laser with a 1 MHz pulse repetition rate and a femtosecond amplified Ti:sapphire laser with a 1 kHz repetition rate. Confocal Raman and fluorescence microscopy were used to study structural changes in the waveguides written with both systems. A broad fluorescence band, centered at 650 nm, associated with non-bridging oxygen hole center (NBOHC) defects was observed after waveguide fabrication with the MHz laser. With the kHz laser system these defects were only observed for pulse energies above 1 {mu}J. Far fewer NBOHC defects were formed with the MHz laser than with kHz writing, possibly due to thermal annealing driven by heat accumulation effects at 1 MHz. When the kHz laser was used with pulse energies below 1 {mu}J, the predominant fluorescence was centered at 550 nm, a band assigned to the presence of silicon clusters (E{prime}{sub {delta}}). We also observed an increase in the intensity of the 605 cm{sup -1} Raman peak relative to the total Raman intensity, corresponding to an increase in the concentration of 3-membered rings in the lines fabricated with both laser systems.

  5. Pepsin immobilized in dextran-modified fused-silica capillaries for on-line protein digestion and peptide mapping

    Energy Technology Data Exchange (ETDEWEB)

    Stigter, E.C.A. [Division of Biomedical Analysis, Department of Pharmaceutical Sciences, Faculty of Science, Utrecht University, Sorbonnelaan 16, 3584 CA Utrecht (Netherlands)], E-mail: e.c.a.stigter@uu.nl; Jong, G.J. de; Bennekom, W.P. van [Division of Biomedical Analysis, Department of Pharmaceutical Sciences, Faculty of Science, Utrecht University, Sorbonnelaan 16, 3584 CA Utrecht (Netherlands)

    2008-07-07

    On-line digestion of proteins under acidic conditions was studied using micro-reactors consisting of dextran-modified fused-silica capillaries with covalently immobilized pepsin. The proteins used in this study differed in molecular weight, isoelectric point and sample composition. The injected protein samples were completely digested in 3 min and the digest was analyzed with micro-high performance liquid chromatography (HPLC) and tandem mass spectrometry (MS/MS). The different proteins present in the samples could be identified with a Mascot database search on the basis of auto-MS/MS data. It proved also to be possible to digest and analyze protein mixtures with a sequence coverage of 55% and 97% for the haemoglobin {beta}- and {alpha}-chain, respectively, and 35-55% for the various casein variants. Protease auto-digestion, sample carry-over and loss of signal due to adsorption of the injected proteins were not observed. The backpressure of the reactor is low which makes coupling to systems such as Surface Plasmon Resonance biosensors, which do not tolerate too high pressure, possible. The reactor was stable for at least 40 days when used continuously.

  6. Pepsin immobilized in dextran-modified fused-silica capillaries for on-line protein digestion and peptide mapping.

    Science.gov (United States)

    Stigter, E C A; de Jong, G J; van Bennekom, W P

    2008-07-07

    On-line digestion of proteins under acidic conditions was studied using micro-reactors consisting of dextran-modified fused-silica capillaries with covalently immobilized pepsin. The proteins used in this study differed in molecular weight, isoelectric point and sample composition. The injected protein samples were completely digested in 3 min and the digest was analyzed with micro-high performance liquid chromatography (HPLC) and tandem mass spectrometry (MS/MS). The different proteins present in the samples could be identified with a Mascot database search on the basis of auto-MS/MS data. It proved also to be possible to digest and analyze protein mixtures with a sequence coverage of 55% and 97% for the haemoglobin beta- and alpha-chain, respectively, and 35-55% for the various casein variants. Protease auto-digestion, sample carry-over and loss of signal due to adsorption of the injected proteins were not observed. The backpressure of the reactor is low which makes coupling to systems such as Surface Plasmon Resonance biosensors, which do not tolerate too high pressure, possible. The reactor was stable for at least 40 days when used continuously.

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

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Shi-zhen, E-mail: xusz@uestc.edu.cn [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China); Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); Yao, Cai-zhen; Liao, Wei [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); Yuan, Xiao-dong, E-mail: yxd66my@163.com [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); Wang, Tao [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China); Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); Zu, Xiao-tao [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China)

    2016-10-15

    Ablation rates of fused silica were studied as a function of femtosecond laser pulse fluences (0.7–41 J/cm{sup 2}) 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/cm{sup 2}) 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.

  8. Influence of Cutting Speed on Subsurface Damage Morphology and Distribution in Ground Fused Silica

    Directory of Open Access Journals (Sweden)

    Georg Schnurbusch

    2017-08-01

    Full Text Available In optical fabrication, brittle-hard materials are used for numerous applications. Especially for high-performance optics for laser or lithography applications, a complex and consistent production chain is necessary to account for the material properties. Particularly in pre-processing, e.g., for shaping optical components, brittle material behavior is dominant which leads to a rough surface layer with cracks that reach far below the surface. This so called subsurface damage (SSD needs to be removed in subsequent processes like polishing. Therefore, it is essential to know the extent of the SSD induced by shaping for an efficient design of precise corrective processes and for process improvement. Within this work the influence of cutting speed on SSD, in fused silica, induced by grinding has been investigated. To analyze the subsurface crack distribution and the maximum crack depth magnetorheological finishing has been appointed to polish a wedge into the ground surface. The depth profile of SSD was analyzed by image processing. For this purpose a coherent area of the polished wedge has been recorded by stitching microscopy. Taking the form deviation of the ground surface in to account to determine the actual depth beneath surface, the accuracy of the SSD-evaluation could be improved significantly. The experiments reveal a clear influence of the cutting speed on SSD, higher cutting speeds generate less SSD. Besides the influence on the maximum crack depth an influence on the crack length itself could be verified. Based on image analysis it was possible, to predict the maximum depth of cracks by means of crack length.

  9. Comparing monolithic and fused core HPLC columns for fast chromatographic analysis of fat-soluble vitamins.

    Science.gov (United States)

    Kurdi, Said El; Muaileq, Dina Abu; Alhazmi, Hassan A; Bratty, Mohammed Al; Deeb, Sami El

    2017-06-27

    HPLC stationary phases of monolithic and fused core type can be used to achieve fast chromatographic separation as an alternative to UPLC. In this study, monolithic and fused core stationary phases are compared for fast separation of four fat-soluble vitamins. Three new methods on the first and second generation monolithic silica RP-18e columns and a fused core pentafluoro-phenyl propyl column were developed. Application of three fused core columns offered comparable separations of retinyl palmitate, DL-α-tocopheryl acetate, cholecalciferol and menadione in terms of elution speed and separation efficiency. Separation was achieved in approx. 5 min with good resolution (Rs > 5) and precision (RSD ≤ 0.6 %). Monolithic columns showed, however, a higher number of theoretical plates, better precision and lower column backpressure than the fused core column. The three developed methods were successfully applied to separate and quantitate fat-soluble vitamins in commercial products.

  10. Graphene oxide bonded fused-silica fiber for solid-phase microextraction-gas chromatography of polycyclic aromatic hydrocarbons in water.

    Science.gov (United States)

    Xu, Lili; Feng, Juanjuan; Li, Jubai; Liu, Xia; Jiang, Shengxiang

    2012-01-01

    A novel chemically bonded graphene oxide/fused-silica fiber was prepared and applied in solid-phase microextraction of six polycyclic aromatic hydrocarbons from water samples coupled with gas chromatography. It exhibited high extraction efficiency and excellent stability. Effects of extraction time, extraction temperature, ionic strength, stirring rate and desorption conditions were investigated and optimized in our work. Detection limits to the six polycyclic aromatic hydrocarbons were less than 0.08 μg/L, and their calibration curves were all linear (R(2)≥0.9954) in the range from 0.05 to 200 μg/L. Single fiber repeatability and fiber-to-fiber reproducibility were less than 6.13 and 15.87%, respectively. This novel fiber was then utilized to analyze two real water samples from the Yellow River and local waterworks, and the recoveries of samples spiked at 1 and 10 μg/L ranged from 84.48 to 118.24%. Compared with other coating materials, this graphene oxide-coated fiber showed many advantages: wide linear range, low detection limit, and good stability in acid, alkali, organic solutions and at high temperature. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. An Anomaly Detector Based on Multi-aperture Mapping for Hyperspectral Data

    Directory of Open Access Journals (Sweden)

    LI Min

    2016-10-01

    Full Text Available Considering the correlationship of spectral content between anomaly and clutter background, inaccurate selection of background pixels induced estimation error of background model. In order to solve the above problems, a multi-aperture mapping based anomaly detector was proposed in this paper. Firstly, differing from background model which focused on feature extraction of background, multi-aperture mapping of hyperspectral data characterized the feature of whole hyperspectral data. According to constructed basis set of multi-aperture mapping, anomaly salience index of every test pixel was proposed to measure the relative statistic difference. Secondly, in order to analysis the moderate salience anomaly precisely, membership value was constructed to identify anomaly salience of test pixels continuously based on fuzzy logical theory. At same time, weighted iterative estimation of multi-aperture mapping was expected to converge adaptively with membership value as weight. Thirdly, classical defuzzification was proposed to fuse different detection results. Hyperspectral data was used in the experiments, and the robustness and sensitivity to anomaly with lower silence of proposed detector were tested.

  12. Formation of nanograting in fused silica by temporally delayed femtosecond double-pulse irradiation

    Science.gov (United States)

    Wang, Haodong; Song, Juan; Li, Qin; Zeng, Xianglong; Dai, Ye

    2018-04-01

    A 1 kHz femtosecond double-pulse sequence irradiation is used to study the temporal evolution of nanograting in fused silica by controlling the delay times and polarization combinations of two independent beams from a Mach–Zehnder interferometer. A lateral laser-scan experiment with speed at 5 µm s‑1 and each pulse energy of 1 µJ is firstly performed with the delay time from sub-picosecond to 10 ps, and then the written nanostructures are systematically studied under a cross-polarized microscope because the intensity of birefringence signal nearly corresponds to optical retardance and development level of the induced nanograting. The trend shows that the induced nanogratings can continue developing with a decrease of delay time in the case of the linear polarization pulse arriving before. In another vertical laser-scan experiment at the same speed and pulse energy, the morphologies of nanogratings embedded in the lines are characterized by scanning electron microscope after mechanical polishing and chemical etching. The self-organized patterns have a commonly spatial period of 200–300 nm and the orientation is always perpendicular to the polarization of the first laser pulse, and the second pulse in each sequence seems to promote the as-formed nanograting developing further even if the polarized direction is different from the previous pulse. These new findings verify again that a localized memory effect can make positive feedback to reinforce the patterned nanostripes. In that process, the impact ionization from the seed electrons left by the first pulse excitation and the photoionization of self-trapped excitons with lower ionization threshold results in an increase of the re-excited carriers during the second pulse irradiation and the subsequent development of the as-formed nanograting. Our result provides further proofs for understanding the physical mechanism of nanograting strongly connection with the interplay on multiple ionization channels.

  13. Comparing monolithic and fused core HPLC columns for fast chromatographic analysis of fat-soluble vitamins

    Directory of Open Access Journals (Sweden)

    Kurdi Said El

    2017-06-01

    Full Text Available HPLC stationary phases of monolithic and fused core type can be used to achieve fast chromatographic separation as an alternative to UPLC. In this study, monolithic and fused core stationary phases are compared for fast separation of four fat-soluble vitamins. Three new methods on the first and second generation monolithic silica RP-18e columns and a fused core pentafluoro-phenyl propyl column were developed. Application of three fused core columns offered comparable separations of retinyl palmitate, DL-α-tocopheryl acetate, cholecalciferol and menadione in terms of elution speed and separation efficiency. Separation was achieved in approx. 5 min with good resolution (Rs > 5 and precision (RSD ≤ 0.6 %. Monolithic columns showed, however, a higher number of theoretical plates, better precision and lower column backpressure than the fused core column. The three developed methods were successfully applied to separate and quantitate fat-soluble vitamins in commercial products.

  14. Chiral separation of methoxamine and lobeline in capillary zone electrophoresis using ethylbenzene-deactivated fused-silica capillary columns and cyclodextrins as buffer additives.

    Science.gov (United States)

    Russo, M V

    2002-08-01

    The complete chiral separation of methoxamine and lobeline was achieved by capillary zone electrophoresis on an ethylbenzene-deactivated fused-silica capillary column and with cyclodextrins (CDs) as buffer additives. Among the CDs investigated in this study, i.e. alpha-CD, beta-CD, dimethyl-beta-CD, hydroxypropyl-beta-CD and gamma-CD, all the three beta-type CDs showed chiral recognition on the two drugs investigated. Under the investigated conditions, the baseline chiral separation of methoxamine can be achieved with 90 mM Tris-H3PO4 (pH 2.5) containing 11.5 mM of the three beta-type CDs, with dimethyl-beta-CD giving the best resolution, whereas the baseline chiral separation of lobeline can be realized by using 90 mM Tris-H3PO4 buffer (pH 2.5) containing 5.8 mM dimethyl-beta-CD or 29.5 mM hydroxypropyl-beta-CD.

  15. 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

    Science.gov (United States)

    Shang, L.; Chou, I-Ming; Lu, W.; Burruss, Robert; 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 H2were 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:lnD=-(16.471±0.035)-44589±139RT(R2=0.99991)">lnD=-(16.471±0.035)-44589±139RT(R2=0.99991)where R is the gas constant (8.3145 J/mol K), T in Kelvin, and errors at 1σ 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.

  16. Self-phase modulation in a thin fused silica plate upon interaction with a converging beam of down-chirped femtosecond radiation

    Energy Technology Data Exchange (ETDEWEB)

    Grudtsyn, Ya V; Zubarev, I G; Mamaev, S B; Mikheev, L D; Stepanov, S G; Yalovoi, V I [P N Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Koribut, A V [Moscow Institute of Physics and Technology (State University), Dolgoprudny, Moscow region (Russian Federation); Kuchik, I E; Trofimov, V A [M. V. Lomonosov Moscow State University, Moscow (Russian Federation); Semjonov, S L [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation)

    2015-05-31

    The mechanism of spectral broadening and self-compression of down-chirped femtosecond pulses in the visible range (473 nm) upon nonlinear interaction of a converging Gaussian beam with a 1-mm-thick fused silica plate is experimentally and theoretically investigated. It is found experimentally that when the intensity increases and plasma is formed in the sample, the regime of femtosecond pulse splitting is transformed into the single-pulse generation regime during nonlinear interaction. As a result of selfcompression, the duration of the initial transform-limited pulse is reduced by a factor of 3. Based on the numerical solution of the generalised nonlinear Schrödinger equation, with the plasma formation disregarded, it is shown that the profile, spectrum and temporal phase of the pulse transmitted through the sample acquire a stationary shape behind the focal plane of the focusing mirror. The calculation results are in good agreement with experimental data. The possibility of parametric amplification of the pulse spectral components under given experimental conditions is discussed. (extreme light fields and their applications)

  17. Structural changes in femtosecond laser modified regions inside fused silica

    International Nuclear Information System (INIS)

    Juodkazis, Saulius; Kohara, Shinji; Ohishi, Yasuo; Hirao, Norihisa; Vailionis, Arturas; Mizeikis, Vygantas; Saito, Akira; Rode, Andrei

    2010-01-01

    Structural characterization of photomodified microvolumes formed by tightly focused femtosecond laser pulses inside silica glass was carried out using synchrotron x-ray diffraction. The observed distinct separation between the O–O and Si–Si pair correlation peaks can be interpreted as a phase separation induced by microexplosions at the focal volume. The mechanisms of structural transitions induced by femtosecond laser pulses inside dielectrics are discussed

  18. Evaluation of coded aperture radiation detectors using a Bayesian approach

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Kyle, E-mail: mille856@andrew.cmu.edu [Auton Lab, The Robotics Institute, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213 (United States); Huggins, Peter [Auton Lab, The Robotics Institute, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213 (United States); Labov, Simon; Nelson, Karl [Lawrence Livermore National Laboratory, Livermore, CA (United States); Dubrawski, Artur [Auton Lab, The Robotics Institute, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213 (United States)

    2016-12-11

    We investigate tradeoffs arising from the use of coded aperture gamma-ray spectrometry to detect and localize sources of harmful radiation in the presence of noisy background. Using an example application scenario of area monitoring and search, we empirically evaluate weakly supervised spectral, spatial, and hybrid spatio-spectral algorithms for scoring individual observations, and two alternative methods of fusing evidence obtained from multiple observations. Results of our experiments confirm the intuition that directional information provided by spectrometers masked with coded aperture enables gains in source localization accuracy, but at the expense of reduced probability of detection. Losses in detection performance can however be to a substantial extent reclaimed by using our new spatial and spatio-spectral scoring methods which rely on realistic assumptions regarding masking and its impact on measured photon distributions.

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

    Science.gov (United States)

    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.

  20. Time-resolved imaging of filamentary damage on the exit surface of fused silica induced by 1064 nm nanosecond laser pulse

    International Nuclear Information System (INIS)

    Chao, Shen; Xiang’ai, Cheng; Tian, Jiang; Zhiwu, Zhu; Yifan, Dai

    2015-01-01

    Laser-induced damage on the exit surface of fused silica with a filament was observed. The filament has a central hollow core surrounded by molten materials and no obvious cracks could be observed. The critical intensity for the transition from pure surface damage (SD) to filamentary damage (FD) was measured. Time-resolved shadowgraphic microscopy with nanosecond time resolution was employed to compare the propagation of shock wave and material response in the SD and FD process. The main different features during the material response process include: (i) thermoelastic shock waves launched in FD were multiple and a column envelope was observed in the lateral direction; (ii) more energy is deposited in the bulk for FD resulting to a lower speed of shock wave in air; (iii) the overall time for establishing the main character of the damage site for FD was shorter because of the absence of crack expansion. Self-focusing and temperature-activated optical absorption enhancement of the bulk material are discussed to explain the morphology difference between SD and FD and the evolution of filament length under different incident intensities. (paper)

  1. Apertures

    CERN Document Server

    Hansen, R C

    2014-01-01

    Microwave Scanning Antennas, Volume I: Apertures is a comprehensive account of phased arrays, multiple beam arrays, time domain and synthetic apertures, and adaptive antennas. Advances in continuous apertures and near field theory are discussed. Low noise and monopulse apertures, optical scanners, and large radomes are also covered, along with radio astronomy instruments and associated theory.Comprised of five chapters, this volume begins with an overview of aperture theory as well as aperture distributions and near field theory. The second and third chapters deal with mechanically steered and

  2. Ionic Liquid-Bonded Fused Silica as a New Solid-Phase Microextraction Fiber for the Liquid Chromatographic Determination of Bisphenol A as an Endocrine Disruptor.

    Science.gov (United States)

    Mohammadnezhad, Nasim; Matin, Amir Abbas; Samadi, Naser; Shomali, Ashkan; Valizadeh, Hassan

    2017-01-01

    Linear ionic liquid bonded to fused silica and its application as a solid-phase microextraction fiber for the extraction of bisphenol A (BPA) from water samples were studied. After optimization of microextraction conditions (15 mL sample volume, extraction time of 40 min, extraction temperature of 30 ± 1°C, 300 μL acetonitrile as the desorption solvent, and desorption time of 7 min), the fiber was used to extract BPA from packed mineral water, followed by HPLC-UV on an XDB-C18 column (150 × 4.6 mm id, 3.5 μm particle) with a mobile phase of acetonitrile-water (45 + 55%, v/v) and flow rate of 1 mL . min-1). A low LOD (0.20 μg . L-1) and good linearity (0.9977) in the calibration graph indicated that the proposed method was suitable for the determination of BPA.

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Chambonneau, M., E-mail: maxime.chambonneau@hotmail.fr; Grua, P.; Rullier, J.-L.; Lamaignère, L. [CEA CESTA, 15 Avenue des Sablières, CS 60001, 33116 Le Barp Cedex (France); Natoli, J.-Y. [Aix Marseille Université, CNRS, Centrale Marseille, Institut Fresnel, UMR 7249, 13013 Marseille (France)

    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.

  5. CLASSIFIER FUSION OF HIGH-RESOLUTION OPTICAL AND SYNTHETIC APERTURE RADAR (SAR SATELLITE IMAGERY FOR CLASSIFICATION IN URBAN AREA

    Directory of Open Access Journals (Sweden)

    T. Alipour Fard

    2014-10-01

    Full Text Available This study concerned with fusion of synthetic aperture radar and optical satellite imagery. Due to the difference in the underlying sensor technology, data from synthetic aperture radar (SAR and optical sensors refer to different properties of the observed scene and it is believed that when they are fused together, they complement each other to improve the performance of a particular application. In this paper, two category of features are generate and six classifier fusion operators implemented and evaluated. Implementation results show significant improvement in the classification accuracy.

  6. Modeling laser-induced surface cracks in silica at 355 nm

    International Nuclear Information System (INIS)

    Feit, M.D.

    1997-01-01

    Starting from the absorption of laser energy at a subsurface nanoparticle in fused silica, we simulate the consequent buildup of stresses and resulting mechanical material damage . The simulation indicates the formation of micropits with size comparable to a wavelength, similar to experimental observation. Possible mechanisms for enhanced local light absorbtion are discussed

  7. XAFS study on silica glasses irradiated in a nuclear reactor

    International Nuclear Information System (INIS)

    Yoshida, Tomoko; Yoshida, Hisao; Hara, Takanobu; Ii, Tatsuya; Okada, Tomohisa; Tanabe, Tetsuo

    2000-01-01

    X-ray absorption technique (XANES and EXAFS) was applied to study the local structures of silica glasses before and after the irradiation in a nuclear reactor. Although our separate photoluminescence (PL) measurements clearly showed the different aspects about oxygen vacancies in these samples, i.e., at least the B 2β type oxygen-deficient center exists as an intrinsic defect in the fused silica glass while another type B 2α center is formed in the synthesized silica glass, such differences did not directly reflect on the X-ray absorption spectra (XANES and EXAFS). However, the curve-fitting analysis of EXAFS showed that the number of oxygen atoms coordinated to Si relatively increased after the irradiation. This result may indicate the occurrence of the structural relaxation in the irradiated samples, that is, a slightly distorted SiO 4 tetrahedra in silica glasses relaxed to the regular SiO 4 tetrahedra due to the break of some connections between SiO 4 units in the silica glasses. Thus, the X-ray absorption technique gave the important information of the in-reactor irradiated silica glasses which complements the results obtained from PL measurements

  8. Investigations on the homogeneity of silica glass and on the order of X-amorphous silica by luminescence measurements

    International Nuclear Information System (INIS)

    Boden, G.

    1982-08-01

    Silica glasses melted from crystalline SiO 2 were exposed to ionizing radiation. At room temperature the spatial intensity distribution of the emitted luminescent radiation has been recorded by means of photographic or autoradiographic materials. Thereby schlieren and inhomogeneities are made visible and information is obtained on the melting process of the crystalline SiO 2 . Synthetic fused silica made from SiCl 4 shows no luminescent radiation. Depending on the penetration depth of the ionizing radiation the bulk or the surface of the sample can be studied. The decay curves of the integral luminescence intensity yield data on inhomogeneities in the silica glass leading to conclusions on order state and structure. The luminescence intensity and its half-life are a measure for the inhomogeneity of the silica glass and the existence of so-called 'preordered states'. This connection between luminescence intensity and the order state is found also with other X-amorphous SiO 2 modifications: silica gel, precipitated silicic acids, porous SiO 2 glasses, aerosil, thin SiO 2 layers, mechanically activated quartz: whereas no luminescence phenomena occur in disordered nearly ideally amorphous SiO 2 species, the luminescence increases with increasing order degree of the SiO 2 network and attains a high intensity in the case of the crystalline SiO 2 modifications quartz and cristobalite

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Shen, N. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Matthews, M. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Elhadj, S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Miller, P. E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Nelson, A. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Hamilton, J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    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.

  11. Optical absorption of neutron-irradiated silica fibers

    International Nuclear Information System (INIS)

    Cooke, D.W.; Farnum, E.H.; Bennett, B.L.

    1996-01-01

    Induced-loss spectra of silica-based optical fibers exposed to high (10 23 n-m -2 ) and low (10 21 n-m -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 (∼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 ∼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 ∼800 to 2000 nm, and the high-OH content fibers are the choice for the interval ∼400 to 800 nm

  12. Precise Aperture-Dependent Motion Compensation with Frequency Domain Fast Back-Projection Algorithm

    Directory of Open Access Journals (Sweden)

    Man Zhang

    2017-10-01

    Full Text Available Precise azimuth-variant motion compensation (MOCO is an essential and difficult task for high-resolution synthetic aperture radar (SAR imagery. In conventional post-filtering approaches, residual azimuth-variant motion errors are generally compensated through a set of spatial post-filters, where the coarse-focused image is segmented into overlapped blocks concerning the azimuth-dependent residual errors. However, image domain post-filtering approaches, such as precise topography- and aperture-dependent motion compensation algorithm (PTA, have difficulty of robustness in declining, when strong motion errors are involved in the coarse-focused image. In this case, in order to capture the complete motion blurring function within each image block, both the block size and the overlapped part need necessary extension leading to degeneration of efficiency and robustness inevitably. Herein, a frequency domain fast back-projection algorithm (FDFBPA is introduced to deal with strong azimuth-variant motion errors. FDFBPA disposes of the azimuth-variant motion errors based on a precise azimuth spectrum expression in the azimuth wavenumber domain. First, a wavenumber domain sub-aperture processing strategy is introduced to accelerate computation. After that, the azimuth wavenumber spectrum is partitioned into a set of wavenumber blocks, and each block is formed into a sub-aperture coarse resolution image via the back-projection integral. Then, the sub-aperture images are straightforwardly fused together in azimuth wavenumber domain to obtain a full resolution image. Moreover, chirp-Z transform (CZT is also introduced to implement the sub-aperture back-projection integral, increasing the efficiency of the algorithm. By disusing the image domain post-filtering strategy, robustness of the proposed algorithm is improved. Both simulation and real-measured data experiments demonstrate the effectiveness and superiority of the proposal.

  13. Conversion of South African coal fly ash into high-purity ZSM-5 zeolite without additional source of silica or alumina and its application as a methanol-to-olefins catalyst

    CSIR Research Space (South Africa)

    Missengue, RNM

    2018-03-01

    Full Text Available Characteristics of ZSM-5 synthesized from H2SO4-treated coal fly ash and fused coal fly ash extracts are compared in this study. In the synthesis process, fused coal fly ash extract (without an additional silica source) was used in the synthesis...

  14. About a New Type of Fuse Based on the Controllable Fusing Effect

    Directory of Open Access Journals (Sweden)

    PLESCA, A.

    2009-06-01

    Full Text Available Fuses are among the best known of electrical devices and there are an extremely large number in use throughout the world. Beside of the advantageous features, the nowadays fuses have certain drawbacks. Therefore, a new type of fuse based on controllable fusing concept is proposed and a study as regards the total clearing time is done. The new concept has been validated through many experimental tests at different current values. The new type of fuse based on controllable fusing concept can be integrated within an overcurrent protection system especially to protect power semiconductors where the Joule integral criterion is better satisfied.

  15. Tunable thick porous silica coating fabricated by multilayer-by-multilayer bonding of silica nanoparticles for open-tubular capillary chromatographic separation.

    Science.gov (United States)

    Qu, Qishu; Liu, Yuanyuan; Shi, Wenjun; Yan, Chao; Tang, Xiaoqing

    2015-06-19

    A simple coating procedure employing a multilayer-by-multilayer process to modify the inner surface of bare fused-silica capillaries with silica nanoparticles was established. The silica nanoparticles were adsorbed onto the capillary wall via a strong electrostatic interaction between amino functional groups and silica particles. The thickness of the coating could be tuned from 130 to 600 nm by increasing the coating cycles from one to three. Both the retention factor and the resolution were greatly increased with increasing coating cycles. The loading capacity determined by naphthalene in the column with three coating cycles is 152.1 pmol. The effects of buffer concentration and pH value on the stability of the coating were evaluated. The retention reproducibility of the separation of toluene was 0.8, 1.2, 2.3, and 4.5%, respectively, for run-to-run, day-to-day, column-to-column, and batch-to-batch, respectively. The chromatographic performance of these columns was evaluated by both capillary liquid chromatography and open-tubular capillary electrochromatography (OT-CEC). Separation of aromatic hydrocarbons in the column with three coating cycles provided high theoretical plate numbers (up to 269,280 plates m(-1) for toluene) and short separation time (<15 min) by using OT-CEC mode. The method was also used to separate egg white proteins. Both acidic and basic proteins as well as four glycoisoforms were separated in a single run. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Enhanced photoelastic modulation in silica phononic crystal cavities

    Science.gov (United States)

    Kim, Ingi; Iwamoto, Satoshi; Arakawa, Yasuhiko

    2018-04-01

    The enhanced photoelastic modulation in quasi-one-dimensional (1D) phononic crystal (PnC) cavities made of fused silica is experimentally demonstrated. A confined acoustic wave in the cavity can induce a large birefringence through the photoelastic effect and enable larger optical modulation amplitude at the same acoustic power. We observe a phase retardation of ∼26 mrad of light passing through the cavity when the exciting acoustic frequency is tuned to the cavity mode resonance of ∼500 kHz at 2.5 V. In the present experiment, a 16-fold enhancement of retardation in the PnC cavity is demonstrated compared with that in a bar-shaped silica structure. Spatially resolved optical retardation measurement reveals that the large retardation is realized only around the cavity reflecting the localized nature of the acoustic cavity mode. The enhanced interactions between acoustic waves and light can be utilized to improve the performance of acousto-optic devices such as photoelastic modulators.

  17. Control of silicification by genetically engineered fusion proteins: Silk–silica binding peptides

    Science.gov (United States)

    Zhou, Shun; Huang, Wenwen; Belton, David J.; Simmons, Leo O.; Perry, Carole C.; Wang, Xiaoqin; Kaplan, David L.

    2014-01-01

    In the present study, an artificial spider silk gene, 6mer, derived from the consensus sequence of Nephila clavipes dragline silk gene, was fused with different silica-binding peptides (SiBPs), A1, A3 and R5, to study the impact of the fusion protein sequence chemistry on silica formation and the ability to generate a silk–silica composite in two different bioinspired silicification systems: solution–solution and solution– solid. Condensed silica nanoscale particles (600–800 nm) were formed in the presence of the recombinant silk and chimeras, which were smaller than those formed by 15mer-SiBP chimeras [1], revealing that the molecular weight of the silk domain correlated to the sizes of the condensed silica particles in the solution system. In addition, the chimeras (6mer-A1/A3/R5) produced smaller condensed silica particles than the control (6mer), revealing that the silica particle size formed in the solution system is controlled by the size of protein assemblies in solution. In the solution–solid interface system, silicification reactions were performed on the surface of films fabricated from the recombinant silk proteins and chimeras and then treated to induce β-sheet formation. A higher density of condensed silica formed on the films containing the lowest β-sheet content while the films with the highest β-sheet content precipitated the lowest density of silica, revealing an inverse correlation between the β-sheet secondary structure and the silica content formed on the films. Intriguingly, the 6mer-A3 showed the highest rate of silica condensation but the lowest density of silica deposition on the films, compared with 6mer-A1 and -R5, revealing antagonistic crosstalk between the silk and the SiBP domains in terms of protein assembly. These findings offer a path forward in the tailoring of biopolymer–silica composites for biomaterial related needs. PMID:25462851

  18. Control of silicification by genetically engineered fusion proteins: silk-silica binding peptides.

    Science.gov (United States)

    Zhou, Shun; Huang, Wenwen; Belton, David J; Simmons, Leo O; Perry, Carole C; Wang, Xiaoqin; Kaplan, David L

    2015-03-01

    In the present study, an artificial spider silk gene, 6mer, derived from the consensus sequence of Nephila clavipes dragline silk gene, was fused with different silica-binding peptides (SiBPs), A1, A3 and R5, to study the impact of the fusion protein sequence chemistry on silica formation and the ability to generate a silk-silica composite in two different bioinspired silicification systems: solution-solution and solution-solid. Condensed silica nanoscale particles (600-800 nm) were formed in the presence of the recombinant silk and chimeras, which were smaller than those formed by 15mer-SiBP chimeras, revealing that the molecular weight of the silk domain correlated to the sizes of the condensed silica particles in the solution system. In addition, the chimeras (6mer-A1/A3/R5) produced smaller condensed silica particles than the control (6mer), revealing that the silica particle size formed in the solution system is controlled by the size of protein assemblies in solution. In the solution-solid interface system, silicification reactions were performed on the surface of films fabricated from the recombinant silk proteins and chimeras and then treated to induce β-sheet formation. A higher density of condensed silica formed on the films containing the lowest β-sheet content while the films with the highest β-sheet content precipitated the lowest density of silica, revealing an inverse correlation between the β-sheet secondary structure and the silica content formed on the films. Intriguingly, the 6mer-A3 showed the highest rate of silica condensation but the lowest density of silica deposition on the films, compared with 6mer-A1 and -R5, revealing antagonistic crosstalk between the silk and the SiBP domains in terms of protein assembly. These findings offer a path forward in the tailoring of biopolymer-silica composites for biomaterial related needs. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

    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

  20. Fabrication of 3D electro-thermal micro actuators in silica glass by femtosecond laser wet etch and microsolidics

    Science.gov (United States)

    Li, Qichao; Shan, Chao; Yang, Qing; Chen, Feng; Bian, Hao; Hou, Xun

    2017-02-01

    This paper demonstrates a novel electro-thermal micro actuator's design, fabrication and device tests which combine microfluidic technology and microsolidics process. A three-dimensional solenoid microchannel with high aspect ratio is fabricated inside the silica glass by an improved femtosecond laser wet etch (FLWE) technology, and the diameter of the spiral coil is only 200 μm. Molten alloy (Bi/In/Sn/Pb) with high melting point is injected into the three-dimensional solenoid microchannel inside the silica glass , then it solidifys and forms an electro-thermal micro actuator. The device is capable of achieving precise temperature control and quick response, and can also be easily integrated into MEMS, sensors and `lab on a chip' (LOC) platform inside the fused silica substrate.

  1. Vibrational and electronic spectroscopy of ion-implantation-induced defects in fused silica and crystalline quartz

    International Nuclear Information System (INIS)

    Arnold, G.W.

    1978-01-01

    Defects produced by implantation of various atomic species in fused and crystalline SiO 2 were studied using infrared reflection spectroscopy (IRS) with UV-visible spectroscopy. We observe a new vibrational band at 830 cm -1 which is tentatively associated with the creation of two nonbridging O atoms in SiO 4 units. Numerous chemical effects were also observed, including evidence for chemical incorporation of Li and anomalously large O-vacancy production for Al + , B + and Si + implantation

  2. Colloidal silica-grouting in demonstration tunnel 2 in ONKALO

    International Nuclear Information System (INIS)

    Hollmen, K.; Sievaenen, U.; Funehag, J.; Granberg, N.; Lyytinen, T.; Syrjaenen, P.

    2013-12-01

    Posiva carried out grouting using colloidal silica as the grouting material and with the time stop method as the design approach.Three fans were pre-grouted at Posiva Oy's research space ONKALO demonstration tunnel 2 in autumn 2011 and early winter 2012. Colloidal silica is a mix of one-component colloidal silica and accelerator. Before gelling, colloidal silica behaves like a Newtonian liquid. Colloidal silica's efficiency of penetrating hydraulic apertures in small fractures in rock is significantly better than that of cement-based grout. The grouting design was based on an analytical calculation model. A new technique was used in the grouting implementation, which primarily differed from the previous technique in regard to vacuum pumping and packers. The goal of the first grouting fan in the demonstration tunnel was to check the functionality of the equipment and the method; therefore, the fan was drilled into rock mass with no hydraulic conducting fractures. The second grouting fan was drilled into rock mass with an observed fairly low hydraulic conductivity that was lower than the start criterion established in Posiva Oy's requirements to manage groundwater inflows. Nevertheless, the grouting was carried out. The sealing effect was estimated from the control holes, and a slight improvement in sealing was noted. The holes of the third grouting fan clearly penetrated a water conductive rock mass. The grouting was carried out in two phases, in which the new holes in the second phase were drilled between the existing ones that were drilled in the first phase. In the third fan, the grouting holes of the first phase were noted to be significantly crooked and the second phase grouting holes were drilled in locations that differed from the original design. The quantity of grouting holes was increased in the second phase. The sealing effect was estimated by monitoring the second phase holes and control holes. Based on observations from the control holes

  3. Convergent Polishing: A Simple, Rapid, Full Aperture Polishing Process of High Quality Optical Flats & Spheres

    Science.gov (United States)

    Suratwala, Tayyab; Steele, Rusty; Feit, Michael; Dylla-Spears, Rebecca; Desjardin, Richard; Mason, Dan; Wong, Lana; Geraghty, Paul; Miller, Phil; Shen, Nan

    2014-01-01

    Convergent Polishing is a novel polishing system and method for finishing flat and spherical glass optics in which a workpiece, independent of its initial shape (i.e., surface figure), will converge to final surface figure with excellent surface quality under a fixed, unchanging set of polishing parameters in a single polishing iteration. In contrast, conventional full aperture polishing methods require multiple, often long, iterative cycles involving polishing, metrology and process changes to achieve the desired surface figure. The Convergent Polishing process is based on the concept of workpiece-lap height mismatch resulting in pressure differential that decreases with removal and results in the workpiece converging to the shape of the lap. The successful implementation of the Convergent Polishing process is a result of the combination of a number of technologies to remove all sources of non-uniform spatial material removal (except for workpiece-lap mismatch) for surface figure convergence and to reduce the number of rogue particles in the system for low scratch densities and low roughness. The Convergent Polishing process has been demonstrated for the fabrication of both flats and spheres of various shapes, sizes, and aspect ratios on various glass materials. The practical impact is that high quality optical components can be fabricated more rapidly, more repeatedly, with less metrology, and with less labor, resulting in lower unit costs. In this study, the Convergent Polishing protocol is specifically described for fabricating 26.5 cm square fused silica flats from a fine ground surface to a polished ~λ/2 surface figure after polishing 4 hr per surface on a 81 cm diameter polisher. PMID:25489745

  4. Dihydropyridine-fused and pyridine-fused coumarins: Reduction on a glassy carbon electrode in dimethylformamide

    International Nuclear Information System (INIS)

    Nuñez-Vergara, Luis J.; Pardo-Jiménez, V.; Barrientos, C.; Olea-Azar, C.A.; Navarrete-Encina, P.A.; Squella, J.A.

    2012-01-01

    In this study, two series of dihydropyridine-fused and pyridine-fused coumarins were synthesised and electrochemically characterised in aprotic medium. In both series, the most easily reducible groups were the endocyclic carbonyl groups. The electrochemical mechanism for both types of compounds is strongly dependent on the experimental time-scale. Cyclic voltammetric (CV) reduction on a glassy carbon electrode (GCE) of the endocyclic carbonyl group of dihydropyridine-fused coumarins involves an ECEC mechanism with two electron transfer steps that are coupled with chemical reactions to produce the corresponding hemiacetal derivative. In the case of pyridine-fused coumarins, CV reduction of the endocyclic carbonyl group involves an EEC mechanism. ESR studies revealed the presence of a stabilised intermediate only for the pyridine-fused derivatives. Our theoretical study showed a spin density map of radical species delocalised mainly within the coumarin ring, indicating the reduction of the endocyclic carbonyl group. In the case of the dihydropyridine-fused derivatives, the mildly acid hydrogen of the dihydropyridine ring destabilises the radical via a father–son type reaction.

  5. Impact of mechanical stress induced in silica vacuum windows on laser-induced damage.

    Science.gov (United States)

    Gingreau, Clémence; Lanternier, Thomas; Lamaignère, Laurent; Donval, Thierry; Courchinoux, Roger; Leymarie, Christophe; Néauport, Jérôme

    2018-04-15

    At the interface between vacuum and air, optical windows must keep their optical properties, despite being subjected to mechanical stress. In this Letter, we investigate the impact of such stress on the laser-induced damage of fused silica windows at the wavelength of 351 nm in the nanosecond regime. Different stress values, from 1 to 30 MPa, both tensile and compressive, were applied. No effect of the stress on the laser-induced damage was evidenced.

  6. Comparisons of coded aperture imaging using various apertures and decoding methods

    International Nuclear Information System (INIS)

    Chang, L.T.; Macdonald, B.; Perez-Mendez, V.

    1976-07-01

    The utility of coded aperture γ camera imaging of radioisotope distributions in Nuclear Medicine is in its ability to give depth information about a three dimensional source. We have calculated imaging with Fresnel zone plate and multiple pinhole apertures to produce coded shadows and reconstruction of these shadows using correlation, Fresnel diffraction, and Fourier transform deconvolution. Comparisons of the coded apertures and decoding methods are made by evaluating their point response functions both for in-focus and out-of-focus image planes. Background averages and standard deviations were calculated. In some cases, background subtraction was made using combinations of two complementary apertures. Results using deconvolution reconstruction for finite numbers of events are also given

  7. Aperture Photometry Tool

    Science.gov (United States)

    Laher, Russ R.; Gorjian, Varoujan; Rebull, Luisa M.; Masci, Frank J.; Fowler, John W.; Helou, George; Kulkarni, Shrinivas R.; Law, Nicholas M.

    2012-07-01

    Aperture Photometry Tool (APT) is software for astronomers and students interested in manually exploring the photometric qualities of astronomical images. It is a graphical user interface (GUI) designed to allow the image data associated with aperture photometry calculations for point and extended sources to be visualized and, therefore, more effectively analyzed. The finely tuned layout of the GUI, along with judicious use of color-coding and alerting, is intended to give maximal user utility and convenience. Simply mouse-clicking on a source in the displayed image will instantly draw a circular or elliptical aperture and sky annulus around the source and will compute the source intensity and its uncertainty, along with several commonly used measures of the local sky background and its variability. The results are displayed and can be optionally saved to an aperture-photometry-table file and plotted on graphs in various ways using functions available in the software. APT is geared toward processing sources in a small number of images and is not suitable for bulk processing a large number of images, unlike other aperture photometry packages (e.g., SExtractor). However, APT does have a convenient source-list tool that enables calculations for a large number of detections in a given image. The source-list tool can be run either in automatic mode to generate an aperture photometry table quickly or in manual mode to permit inspection and adjustment of the calculation for each individual detection. APT displays a variety of useful graphs with just the push of a button, including image histogram, x and y aperture slices, source scatter plot, sky scatter plot, sky histogram, radial profile, curve of growth, and aperture-photometry-table scatter plots and histograms. APT has many functions for customizing the calculations, including outlier rejection, pixel “picking” and “zapping,” and a selection of source and sky models. The radial-profile-interpolation source

  8. Evaluation of cellulose-binding domain fused to a lipase for the lipase immobilization.

    Science.gov (United States)

    Hwang, Sangpill; Ahn, Jungoh; Lee, Sumin; Lee, Tai Gyu; Haam, Seungjoo; Lee, Kangtaek; Ahn, Ik-Sung; Jung, Joon-Ki

    2004-04-01

    A cellulose-binding domain (CBD) fragment of a cellulase gene of Trichoderma hazianum was fused to a lipase gene of Bacillus stearothermophilus L1 to make a gene cluster for CBD-BSL lipase. The specific activity of CBD-BSL lipase for oil hydrolysis increased by 33% after being immobilized on Avicel (microcrystalline cellulose), whereas those of CBD-BSL lipase and BSL lipase decreased by 16% and 54%, respectively, after being immobilized on silica gel. Although the loss of activity of an enzyme immobilized by adsorption has been reported previously, the loss of activity of the CBD-BSL lipase immobilized on Avicel was less than 3% after 12 h due to the irreversible binding of CBD to Avicel.

  9. Frequency tripling of convergent beam employing crystals tiling in large-aperture high-energy laser facilities

    Science.gov (United States)

    Wang, Junhua; Li, Dazhen; Wang, Bo; Yang, Jing; Yang, Houwen; Wang, Xiaoqian; Cheng, Wenyong

    2017-11-01

    In inertial confinement fusion, ultraviolet laser damage of the fused silica lens is an important limiting factor for load capability of the laser driver. To solve this problem, a new configuration of frequency tripling is proposed in this paper. The frequency tripling crystal is placed on downstream of the focusing lens, thus sum frequency generation of fundamental frequency light and doubling frequency light occurs in the beam convergence path. The focusing lens is only irradiated by fundamental light and doubling frequency lights. Thus, its damage threshold will increase. LiB3O5 (LBO) crystals are employed as frequency tripling crystals for its larger acceptance angle and higher damage threshold than KDP/DKDP crystals'. With the limitation of acceptance angle and crystal growth size are taken into account, the tiling scheme of LBO crystals is proposed and designed optimally to adopt to the total convergence angle of 36.0 mrad. Theoretical results indicate that 3 LBO crystals titling with different cutting angles in θ direction can meet the phase matching condition. Compared with frequency tripling of parallel beam using one LBO crystal, 83.8% (93.1% with 5 LBO crystals tiling) of the frequency tripling conversion efficiency can be obtained employing this new configuration. The results of a principle experiment also support this scheme. By employing this new design, not only the load capacity of a laser driver will be significantly improved, but also the fused silica lens can be changed to K9 glass lens which has the mature technology and low cost.

  10. Parameters for HL-LHC aperture calculations and comparison with aperture measurements

    CERN Document Server

    Bruce, R; Fartoukh, S; Giovannozzi, M; Redaelli, S; Tomas, R; Wenninger, J

    2014-01-01

    When β∗ is squeezed to smaller values in the LHC, the beam size in the inner triplet increases so that the aperture risks to be exposed to unwanted beam losses. A 2D calculation model was used during the design stage to study the aperture margins, both there and at other potential bottlenecks. Based on assumptions on orbit and optics errors, as well as mechanical tolerances, it gives the available aperture in units of the RMS beam size, which can be compared with what can be protected by the collimation system. During the LHC Run I in 2010-2013, several of the error tolerances have been found smaller than the design assumptions. Furthermore, the aperture has been measured with beam several times and the results are compatible with a very well aligned machine, with results close to the design values. In this report, we therefore review the assumptions in the model and propose an updated set of input parameters to be used for aperture calculations at top energy in HL-LHC. The new parameter set is based on th...

  11. Detailed IR aperture measurements

    CERN Document Server

    Bruce, Roderik; Garcia Morales, Hector; Giovannozzi, Massimo; Hermes, Pascal Dominik; Mirarchi, Daniele; Quaranta, Elena; Redaelli, Stefano; Rossi, Carlo; Skowronski, Piotr Krzysztof; Wretborn, Sven Joel; CERN. Geneva. ATS Department

    2016-01-01

    MD 1673 was carried out on October 5 2016, in order to investigate in more detail the available aperture in the LHC high-luminosity insertions at 6.5 TeV and β∗=40 cm. Previous aperture measurements in 2016 during commissioning had shown that the available aperture is at the edge of protection, and that the aperture bottleneck at β∗=40 cm in certain cases is found in the separation plane instead of in the crossing plane. Furthermore, the bottlenecks were consistently found in close to the upstream end of Q3 on the side of the incoming beam, and not in Q2 on the outgoing beam as expected from calculations. Therefore, this MD aimed at measuring IR1 and IR5 separately (at 6.5 TeV and β∗=40 cm, for 185 µrad half crossing angle), to further localize the bottlenecks longitudinally using newly installed BLMs, investigate the difference in aperture between Q2 and Q3, and to see if any aperture can be gained using special orbit bumps.

  12. Silica colloids and their effect on radionuclide sorption. A literature review

    International Nuclear Information System (INIS)

    Hoelttae, P.; Hakanen, M.

    2008-05-01

    Silica sol, commercial colloidal silica manufactured by Eka Chemicals in Bohus, Sweden is a promising inorganic grout material for sealing small fractures in low permeable rock. This literature review collects information about the use of silica sol as an injection grout material, the properties of inorganic, especially silica colloids, colloid contents in granitic groundwater conditions, essential characterization methods and colloid-mediated transport of radionuclides. Objective was to evaluate the release and mobility of silica sol colloids, the effect of the groundwater conditions, the amount of colloids compared with natural colloids in Olkiluoto conditions, radionuclide sorption on colloids and their contribution to radionuclide transport. Silica sol seems to be a feasible material to seal fractures with an aperture as small as 10 μm in low permeable rock. The silica sol gel is sufficiently stable to limit to water ingress during the operational phase, the requirement that the pH should be below 11 is fulfilled and the compatibility with Engineered Barrier System (EBS) materials is expected to be good. No significant influence on the bentonite properties caused by the silica sol is expected when calcium chloride is used as an accelerator but the influence of sodium chloride has not been examined. No significant release of colloids is expected under prevailing groundwater conditions. The long-term (100 y) stability of silica sol gel has not yet been clearly demonstrated and a long-term release of silica colloids cannot be excluded. The question is the amount of colloids, how mobile they are and the influence of possible glacial melt waters. The bentonite buffer used in the EBS system is assumed to be a potential source of colloids. In a study in Olkiluoto, bentonite colloids were found only in low salinity groundwater. In general, low salinity water (total dissolved solids -1 ) favours colloid stability and bentonite colloids can remain stable over long

  13. APT: Aperture Photometry Tool

    Science.gov (United States)

    Laher, Russ

    2012-08-01

    Aperture Photometry Tool (APT) is software for astronomers and students interested in manually exploring the photometric qualities of astronomical images. It has a graphical user interface (GUI) which allows the image data associated with aperture photometry calculations for point and extended sources to be visualized and, therefore, more effectively analyzed. Mouse-clicking on a source in the displayed image draws a circular or elliptical aperture and sky annulus around the source and computes the source intensity and its uncertainty, along with several commonly used measures of the local sky background and its variability. The results are displayed and can be optionally saved to an aperture-photometry-table file and plotted on graphs in various ways using functions available in the software. APT is geared toward processing sources in a small number of images and is not suitable for bulk processing a large number of images, unlike other aperture photometry packages (e.g., SExtractor). However, APT does have a convenient source-list tool that enables calculations for a large number of detections in a given image. The source-list tool can be run either in automatic mode to generate an aperture photometry table quickly or in manual mode to permit inspection and adjustment of the calculation for each individual detection. APT displays a variety of useful graphs, including image histogram, and aperture slices, source scatter plot, sky scatter plot, sky histogram, radial profile, curve of growth, and aperture-photometry-table scatter plots and histograms. APT has functions for customizing calculations, including outlier rejection, pixel “picking” and “zapping,” and a selection of source and sky models. The radial-profile-interpolation source model, accessed via the radial-profile-plot panel, allows recovery of source intensity from pixels with missing data and can be especially beneficial in crowded fields.

  14. Mastering Apple Aperture

    CERN Document Server

    Fitzgerald, Thomas

    2013-01-01

    Written in a conversational style, the author will share his knowledge on advanced Aperture topics with detailed discussions of advanced topics, the theory behind some of those topics and lots of hints and tips for ways to improve your workflow.Photographer's who have a basic understanding of Aperture

  15. Aperture area measurement facility

    Data.gov (United States)

    Federal Laboratory Consortium — NIST has established an absolute aperture area measurement facility for circular and near-circular apertures use in radiometric instruments. The facility consists of...

  16. A preliminary study of the relation between adsorption and CP-MAS-NMR characteristics of fused silica model substrates

    NARCIS (Netherlands)

    Scholten, A.B.; Janssen, J.G.M.; Haan, de J.W.; Cramers, C.A.M.G.; Sandra, P.J.F.; Devos, G.; Sandra, P.

    1993-01-01

    The fumed silica model substrate Aerosil was trimethylsilylated to different extents and studied by the combination of IGC and 29Si CP-MAS-NMR. Dihydroxydisiloxane groups were shown to be chemically more reactive than monohydroxytrisiloxane groups. Chromatographic experiments showed that these

  17. Tissue Harmonic Synthetic Aperture Imaging

    DEFF Research Database (Denmark)

    Rasmussen, Joachim

    The main purpose of this PhD project is to develop an ultrasonic method for tissue harmonic synthetic aperture imaging. The motivation is to advance the field of synthetic aperture imaging in ultrasound, which has shown great potentials in the clinic. Suggestions for synthetic aperture tissue...... system complexity compared to conventional synthetic aperture techniques. In this project, SASB is sought combined with a pulse inversion technique for 2nd harmonic tissue harmonic imaging. The advantages in tissue harmonic imaging (THI) are expected to further improve the image quality of SASB...

  18. Hydrothermal stability of silica, hybrid silica and Zr-doped hybrid silica membranes

    NARCIS (Netherlands)

    ten Hove, Marcel; Luiten-Olieman, Mieke W.J.; Huiskes, Cindy; Nijmeijer, Arian; Winnubst, Louis

    2017-01-01

    Hybrid silica membranes have demonstrated to possess a remarkable hydrothermal stability in pervaporation and gas separation processes allowing them to be used in industrial applications. In several publications the hydrothermal stability of pure silica or that of hybrid silica membranes are

  19. Fumed silica. Fumed silica

    Energy Technology Data Exchange (ETDEWEB)

    Sukawa, T.; Shirono, H. (Nippon Aerosil Co. Ltd., Tokyo (Japan))

    1991-10-18

    The fumed silica is explained in particulate superfineness, high purity, high dispersiveness and other remarkable characteristics, and wide application. The fumed silica, being presently produced, is 7 to 40nm in average primary particulate diameter and 50 to 380m{sup 2}/g in specific surface area. On the surface, there coexist hydrophilic silanol group (Si-OH) and hydrophobic siloxane group (Si-O-Si). There are many characteristics, mutually different between the fumed silica, made hydrophobic by the surface treatment, and untreated hydrophilic silica. The treated silica, if added to the liquid product, serves as agent to heighten the viscosity, prevent the sedimentation and disperse the particles. The highest effect is given to heighten the viscosity in a region of 4 to 9 in pH in water and alcohol. As filling agent to strengthen the elastomer and polymer, and powder product, it gives an effect to prevent the consolidation and improve the fluidity. As for its other applications, utilization is made of particulate superfineness, high purity, thermal insulation properties and adsorption characteristics. 2 to 3 patents are published for it as raw material of quartz glass. 38 refs., 16 figs., 4 tabs.

  20. Survey of coded aperture imaging

    International Nuclear Information System (INIS)

    Barrett, H.H.

    1975-01-01

    The basic principle and limitations of coded aperture imaging for x-ray and gamma cameras are discussed. Current trends include (1) use of time varying apertures, (2) use of ''dilute'' apertures with transmission much less than 50%, and (3) attempts to derive transverse tomographic sections, unblurred by other planes, from coded images

  1. Hybrid coded aperture and Compton imaging using an active mask

    International Nuclear Information System (INIS)

    Schultz, L.J.; Wallace, M.S.; Galassi, M.C.; Hoover, A.S.; Mocko, M.; Palmer, D.M.; Tornga, S.R.; Kippen, R.M.; Hynes, M.V.; Toolin, M.J.; Harris, B.; McElroy, J.E.; Wakeford, D.; Lanza, R.C.; Horn, B.K.P.; Wehe, D.K.

    2009-01-01

    The trimodal imager (TMI) images gamma-ray sources from a mobile platform using both coded aperture (CA) and Compton imaging (CI) modalities. In this paper we will discuss development and performance of image reconstruction algorithms for the TMI. In order to develop algorithms in parallel with detector hardware we are using a GEANT4 [J. Allison, K. Amako, J. Apostolakis, H. Araujo, P.A. Dubois, M. Asai, G. Barrand, R. Capra, S. Chauvie, R. Chytracek, G. Cirrone, G. Cooperman, G. Cosmo, G. Cuttone, G. Daquino, et al., IEEE Trans. Nucl. Sci. NS-53 (1) (2006) 270] based simulation package to produce realistic data sets for code development. The simulation code incorporates detailed detector modeling, contributions from natural background radiation, and validation of simulation results against measured data. Maximum likelihood algorithms for both imaging methods are discussed, as well as a hybrid imaging algorithm wherein CA and CI information is fused to generate a higher fidelity reconstruction.

  2. Immobilization of Styrene-acrylamide Co-polymer on Either Silica Particles or Inner Surface of Silica Capillary for the Separation of D-Glucose Anomers

    International Nuclear Information System (INIS)

    Ali, Faiz; Kim, Yune Sung; Cheong, Won Jo

    2014-01-01

    Styrene-acrylamide co-polymer was immobilized on porous partially sub-2 μm silica monolith particles and inner surface of fused silica capillary (50 μm ID and 28 cm length) to result in μLC and CEC stationary phases, respectively, for separation of anomeric D-glucose derivatives. Reversed addition-fragmentation transfer (RAFT) polymerization was incorporated to induce surface polymerization. Acrylamide was employed to incorporate amide-functionality in the stationary phase. The resultant μLC and CEC stationary phases were able to separate isomers of D-glucose derivatives with high selectivity and efficiency. The mobile phase of 75/ 25 (v/v) acetonitrile (ACN)/water with 0.1% TFA, was used for HPLC with a packed column (1 mm ID, 300 mm length). The effects of pH and ACN composition on anomeric separation of D-glucose in CEC have been examined. A mobile phase of 85/15 (v/v) ACN/30 mM sodium acetate pH 6.7 was found the optimized mobile phase for CEC. The CEC stationary phase also gave good separation of other saccharides such as maltotriose and Dextran 1500 (MW∼1500) with good separation efficiency (number of theoretical plates ∼300,000/m)

  3. Immobilization of Styrene-acrylamide Co-polymer on Either Silica Particles or Inner Surface of Silica Capillary for the Separation of D-Glucose Anomers

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Faiz; Kim, Yune Sung; Cheong, Won Jo [Inha Univ., Incheon (Korea, Republic of)

    2014-02-15

    Styrene-acrylamide co-polymer was immobilized on porous partially sub-2 μm silica monolith particles and inner surface of fused silica capillary (50 μm ID and 28 cm length) to result in μLC and CEC stationary phases, respectively, for separation of anomeric D-glucose derivatives. Reversed addition-fragmentation transfer (RAFT) polymerization was incorporated to induce surface polymerization. Acrylamide was employed to incorporate amide-functionality in the stationary phase. The resultant μLC and CEC stationary phases were able to separate isomers of D-glucose derivatives with high selectivity and efficiency. The mobile phase of 75/ 25 (v/v) acetonitrile (ACN)/water with 0.1% TFA, was used for HPLC with a packed column (1 mm ID, 300 mm length). The effects of pH and ACN composition on anomeric separation of D-glucose in CEC have been examined. A mobile phase of 85/15 (v/v) ACN/30 mM sodium acetate pH 6.7 was found the optimized mobile phase for CEC. The CEC stationary phase also gave good separation of other saccharides such as maltotriose and Dextran 1500 (MW∼1500) with good separation efficiency (number of theoretical plates ∼300,000/m)

  4. Comparative evaluation of fiber fuse models

    International Nuclear Information System (INIS)

    Davis, D.D.; Mettler, S.C.; DiGiovanni, D.J.

    1997-01-01

    A phenomenon which results in the catastrophic destruction of the guiding properties of an optical fiber has been observed at laser power densities on the order of 3 x 10 6 watts/cm 2 in the core. This phenomenon is characterized by the propagation of a bright visible light from the point of initiation toward the laser source. The term 'fiber fuse' has been used because of the similarity in appearance to a burning fuse. The fiber fuse has been shown to start when the end of the fiber is contacted. It has also been initiated spontaneously from mechanical splices. This paper reports experimental data gathered on the fiber fuse and discusses their relationship to proposed physical mechanisms

  5. Aperture averaging in strong oceanic turbulence

    Science.gov (United States)

    Gökçe, Muhsin Caner; Baykal, Yahya

    2018-04-01

    Receiver aperture averaging technique is employed in underwater wireless optical communication (UWOC) systems to mitigate the effects of oceanic turbulence, thus to improve the system performance. The irradiance flux variance is a measure of the intensity fluctuations on a lens of the receiver aperture. Using the modified Rytov theory which uses the small-scale and large-scale spatial filters, and our previously presented expression that shows the atmospheric structure constant in terms of oceanic turbulence parameters, we evaluate the irradiance flux variance and the aperture averaging factor of a spherical wave in strong oceanic turbulence. Irradiance flux variance variations are examined versus the oceanic turbulence parameters and the receiver aperture diameter are examined in strong oceanic turbulence. Also, the effect of the receiver aperture diameter on the aperture averaging factor is presented in strong oceanic turbulence.

  6. Fused Bead Analysis of Diogenite Meteorites

    Science.gov (United States)

    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.

  7. The LHC dynamic aperture

    CERN Document Server

    Koutchouk, Jean-Pierre

    1999-01-01

    In 1996, the expected field errors in the dipoles and quadrupoles yielded a long-term dynamic aperture of some 8sigma at injection. The target was set to 12sigma to account for the limitations of our model (imperfections and dynamics). From scaling laws and tracking, a specification for the field imperfections yielding the target dynamic aperture was deduced. The gap between specification and expected errors is being bridged by i) an improvement of the dipole field quality, ii) a balance between geometric and persistent current errors, iii) additional correction circuits (a3 ,b4 ). With the goal in view, the emphasis has now turned to the sensitivity of the dynamic aperture to the optical parameters.The distortion of the dynamics at the lower amplitudes effectively reached by the particles is minimized by optimizing the distribution of the betatron phase advance. At collision energy, the dynamic aperture is limited by the field imperfections of the low-beta triplets, enhanced by the crossing angle. With corre...

  8. Use of low fusing alloy in dentistry.

    Science.gov (United States)

    Wee, A G; Schneider, R L; Aquilino, S A

    1998-11-01

    Low fusing alloy has been used in dentistry for remount procedures in both fixed and removable prosthodontics, in implant prosthodontics for the fabrication of solid implant casts, in maxillofacial prosthetics as oral radiation shields, and in dental research for its unique properties. Previously, the use of low fusing alloy was thought to offer a high degree of dimensional accuracy. However, multiple in vitro studies have shown that its presumed dimensional accuracy may be questionable. This article reviews the physical properties, metallurgical considerations of low fusing alloy, its applications in dentistry, and a safe, simple method of using low fusing alloy.

  9. Large aperture optical switching devices

    International Nuclear Information System (INIS)

    Goldhar, J.; Henesian, M.A.

    1983-01-01

    We have developed a new approach to constructing large aperture optical switches for next generation inertial confinement fusion lasers. A transparent plasma electrode formed in low pressure ionized gas acts as a conductive coating to allow the uniform charging of the optical faces of an electro-optic material. In this manner large electric fields can be applied longitudinally to large aperture, high aspect ratio Pockels cells. We propose a four-electrode geometry to create the necessary high conductivity plasma sheets, and have demonstrated fast (less than 10 nsec) switching in a 5x5 cm aperture KD*P Pockels cell with such a design. Detaid modelling of Pockels cell performance with plasma electrodes has been carried out for 15 and 30 cm aperture designs

  10. A Radiographic Study of Fused and Geminated Tooth

    Energy Technology Data Exchange (ETDEWEB)

    Park, Chul Jae; Lee, Sang Rae [Dept. of Oral Radiology, College of Dentistry, Kyunhee University, Seoul (Korea, Republic of)

    1990-02-15

    The incidence and several characteristic features of fused and geminated teeth were studied radiographically, with full mouth periapical radiogram and pantomogram, in 4201 patients of mixed dentition and 5358 patients of permanent dentition. The obtained results were as follows: 1. The prevalence was revealed to 2.86%, 0.32%, 0.33%, and 0.06% in deciduous fused tooth, permanent fused tooth, deciduous geminated tooth and permanent geminated tooth respectively, and these anomalies were occurred in female more than male. 2. Fused teeth were observed predominantly in lower anterior teeth area, especially in lateral incisor and canine region, and many cases of deciduous geminated tooth were observed in upper central incisor region. 3. Congenital missing rates of succedaneous tooth in deciduous fused teeth were 57.1%, 85.7%, 71.0%, 69.0% in upper right and left central-lateral incisor regions, lower right and left lateral incisor-canine regions, respectively. 4. Prevalence of dental caries was 42.3%, 18.8% and 5.6% in deciduous fused, deciduous geminated and permanent fused tooth, respectively. 5. In classifying of fused and geminated teeth into 9 type, by following appearance such as number of crown, root, pulp chamber and pulp canal of those teeth, it was more favorable that Type I (2 crown, 2 root, 2 pulp chamber, 2 pulp canal) in deciduous fused tooth and Type IX (1 crown, 1 root, 1 pulp chamber, 1 pulp canal) in permanent used tooth, deciduous and permanent geminated tooth.

  11. A Radiographic Study of Fused and Geminated Tooth

    International Nuclear Information System (INIS)

    Park, Chul Jae; Lee, Sang Rae

    1990-01-01

    The incidence and several characteristic features of fused and geminated teeth were studied radiographically, with full mouth periapical radiogram and pantomogram, in 4201 patients of mixed dentition and 5358 patients of permanent dentition. The obtained results were as follows: 1. The prevalence was revealed to 2.86%, 0.32%, 0.33%, and 0.06% in deciduous fused tooth, permanent fused tooth, deciduous geminated tooth and permanent geminated tooth respectively, and these anomalies were occurred in female more than male. 2. Fused teeth were observed predominantly in lower anterior teeth area, especially in lateral incisor and canine region, and many cases of deciduous geminated tooth were observed in upper central incisor region. 3. Congenital missing rates of succedaneous tooth in deciduous fused teeth were 57.1%, 85.7%, 71.0%, 69.0% in upper right and left central-lateral incisor regions, lower right and left lateral incisor-canine regions, respectively. 4. Prevalence of dental caries was 42.3%, 18.8% and 5.6% in deciduous fused, deciduous geminated and permanent fused tooth, respectively. 5. In classifying of fused and geminated teeth into 9 type, by following appearance such as number of crown, root, pulp chamber and pulp canal of those teeth, it was more favorable that Type I (2 crown, 2 root, 2 pulp chamber, 2 pulp canal) in deciduous fused tooth and Type IX (1 crown, 1 root, 1 pulp chamber, 1 pulp canal) in permanent used tooth, deciduous and permanent geminated tooth.

  12. Additive manufacturing of transparent fused quartz

    Science.gov (United States)

    Luo, Junjie; Hostetler, John M.; Gilbert, Luke; Goldstein, Jonathan T.; Urbas, Augustine M.; Bristow, Douglas A.; Landers, Robert G.; Kinzel, Edward C.

    2018-04-01

    This paper investigates a filament-fed process for additive manufacturing (AM) of fused quartz. Glasses such as fused quartz have significant scientific and engineering applications, which include optics, communications, electronics, and hermetic seals. AM has several attractive benefits such as increased design freedom, faster prototyping, and lower processing costs for small production volumes. However, current research into glass AM has focused primarily on nonoptical applications. Fused quartz is studied here because of its desirability for use in high-quality optics due to its high transmissivity and thermal stability. Fused quartz filaments are fed into a CO2 laser-generated molten region, smoothly depositing material onto the workpiece. Spectroscopy and pyrometry are used to measure the thermal radiation incandescently emitted from the molten region. The effects of the laser power and scan speed are determined by measuring the morphology of single tracks. Thin walls are printed to study the effects of layer-to-layer height. This information is used to deposit solid pieces including a cylindrical-convex shape capable of focusing visible light. The transmittance and index homogeneity of the printed fused quartz are measured. These results show that the filament-fed process has the potential to print transmissive optics.

  13. Porphyrins Fused with Unactivated Polycyclic Aromatic Hydrocarbons

    KAUST Repository

    Diev, Vyacheslav V.; Schlenker, Cody W.; Hanson, Kenneth; Zhong, Qiwen; Zimmerman, Jeramy D.; Forrest, Stephen R.; Thompson, Mark E.

    2012-01-01

    A systematic study of the preparation of porphyrins with extended conjugation by meso,β-fusion with polycyclic aromatic hydrocarbons (PAHs) is reported. The meso-positions of 5,15-unsubstituted porphyrins were readily functionalized with PAHs. Ring fusion using standard Scholl reaction conditions (FeCl 3, dichloromethane) occurs for perylene-substituted porphyrins to give a porphyrin β,meso annulated with perylene rings (0.7:1 ratio of syn and anti isomers). The naphthalene, pyrene, and coronene derivatives do not react under Scholl conditions but are fused using thermal cyclodehydrogenation at high temperatures, giving mixtures of syn and anti isomers of the meso,β-fused porphyrins. For pyrenyl-substituted porphyrins, a thermal method gives synthetically acceptable yields (>30%). Absorption spectra of the fused porphyrins undergo a progressive bathochromic shift in a series of naphthyl (λ max = 730 nm), coronenyl (λ max = 780 nm), pyrenyl (λ max = 815 nm), and perylenyl (λ max = 900 nm) annulated porphyrins. Despite being conjugated with unsubstituted fused PAHs, the β,meso-fused porphyrins are more soluble and processable than the parent nonfused precursors. Pyrenyl-fused porphyrins exhibit strong fluorescence in the near-infrared (NIR) spectral region, with a progressive improvement in luminescent efficiency (up to 13% with λ max = 829 nm) with increasing degree of fusion. Fused pyrenyl-porphyrins have been used as broadband absorption donor materials in photovoltaic cells, leading to devices that show comparatively high photovoltaic efficiencies. © 2011 American Chemical Society.

  14. Porphyrins Fused with Unactivated Polycyclic Aromatic Hydrocarbons

    KAUST Repository

    Diev, Vyacheslav V.

    2012-01-06

    A systematic study of the preparation of porphyrins with extended conjugation by meso,β-fusion with polycyclic aromatic hydrocarbons (PAHs) is reported. The meso-positions of 5,15-unsubstituted porphyrins were readily functionalized with PAHs. Ring fusion using standard Scholl reaction conditions (FeCl 3, dichloromethane) occurs for perylene-substituted porphyrins to give a porphyrin β,meso annulated with perylene rings (0.7:1 ratio of syn and anti isomers). The naphthalene, pyrene, and coronene derivatives do not react under Scholl conditions but are fused using thermal cyclodehydrogenation at high temperatures, giving mixtures of syn and anti isomers of the meso,β-fused porphyrins. For pyrenyl-substituted porphyrins, a thermal method gives synthetically acceptable yields (>30%). Absorption spectra of the fused porphyrins undergo a progressive bathochromic shift in a series of naphthyl (λ max = 730 nm), coronenyl (λ max = 780 nm), pyrenyl (λ max = 815 nm), and perylenyl (λ max = 900 nm) annulated porphyrins. Despite being conjugated with unsubstituted fused PAHs, the β,meso-fused porphyrins are more soluble and processable than the parent nonfused precursors. Pyrenyl-fused porphyrins exhibit strong fluorescence in the near-infrared (NIR) spectral region, with a progressive improvement in luminescent efficiency (up to 13% with λ max = 829 nm) with increasing degree of fusion. Fused pyrenyl-porphyrins have been used as broadband absorption donor materials in photovoltaic cells, leading to devices that show comparatively high photovoltaic efficiencies. © 2011 American Chemical Society.

  15. Range Compressed Holographic Aperture Ladar

    Science.gov (United States)

    2017-06-01

    entropy saturation behavior of the estimator is analytically described. Simultaneous range-compression and aperture synthesis is experimentally...4 2.1 Circular and Inverse -Circular HAL...2.3 Single Aperture, Multi-λ Imaging ...................................................................................... 14 2.4 Simultaneous Range

  16. A silica fiber coated with a ZnO-graphene oxide nanocomposite with high specific surface for use in solid phase microextraction of the antiepileptic drugs diazepam and oxazepam.

    Science.gov (United States)

    Alizadeh, Reza; Salami, Maryam; Seidi, Shahram

    2018-06-02

    A novel ZnO-graphene oxide nanocomposite was prepared and is shown to be a viable coating on fused silica fibers for use in solid phase microextraction (SPME) of diazepam and oxazepam from urine, this followed by thermal desorption and gas chromatographic quantitation using a flame ionization detector. A central composite design was used to optimize extraction time, salt percentage, sample pH and desorption time. Limits of detection are 0.5 μg·L -1 for diazepam and 1.0 μg·L -1 for oxazepam. Repeatability and reproducibility for one fiber (n = 4), expressed as the relative standard deviation at a concentration of 50 μg·L -1 , are 8.3 and 11.3% for diazepam, and 6.7 and 10.1% for oxazepam. The fiber-to-fiber reproducibility is Graphical abstract A hydrothermal method was introduced for preparation of ZnO- GO nano composite on a fused silica fiber as solid phase microextraction with high mechanical, chemical stability and long service life.

  17. InGaAsP/InP-air-aperture microcavities for single-photon sources at 1.55-μm telecommunication band

    Science.gov (United States)

    Guo, Sijie; Zheng, Yanzhen; Weng, Zhuo; Yao, Haicheng; Ju, Yuhao; Zhang, Lei; Ren, Zhilei; Gao, Ruoyao; Wang, Zhiming M.; Song, Hai-Zhi

    2016-11-01

    InGaAsP/InP-air-aperture micropillar cavities are proposed to serve as 1.55-μm single photon sources, which are indispensable in silica-fiber based quantum information processing. Owing to air-apertures introduced to InP layers, and adiabatically tapered distributed Bragg-reflector structures used in the central cavity layers, the pillar diameters can be less than 1 μm, achieving mode volume as small as (λ/n)3, and the quality factors are more than 104 - 105, sufficient to increase the quantum dot emission rate for 100 times and create strong coupling between the optical mode and the 1.55- μm InAs/InP quantum dot emitter. The mode wavelengths and quality factors are found weakly changing with the cavity size and the deviation from the ideal shape, indicating the robustness against the imperfection of the fabrication technique. The fabrication, simply epitaxial growth, dry and chemical etching, is a damage-free and monolithic process, which is advantageous over previous hybrid cavities. The above properties satisfy the requirements of efficient, photonindistinguishable and coherent 1.55-μm quantum dot single photon sources, so the proposed InGaAsP/InP-air-aperture micropillar cavities are prospective candidates for quantum information devices at telecommunication band.

  18. SINA: A test system for proximity fuses

    Science.gov (United States)

    Ruizenaar, M. G. A.

    1989-04-01

    SINA, a signal generator that can be used for testing proximity fuses, is described. The circuitry of proximity fuses is presented; the output signal of the RF circuit results from a mixing of the emitted signal and received signal that is Doppler shifted in frequency by the relative motion of the fuse with respect to the reflecting target of surface. With SINA, digitized and stored target and clutter signals (previously measured) can be transformed to Doppler signals, for example during a real flight. SINA can be used for testing fuse circuitry, for example in the verification of results of computer simulations of the low frequency Doppler signal processing. The software of SINA and its use are explained.

  19. 30 CFR 57.12036 - Fuse removal or replacement.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Fuse removal or replacement. 57.12036 Section 57.12036 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND... Electricity Surface and Underground § 57.12036 Fuse removal or replacement. Fuses shall not be removed or...

  20. Synthetic Aperture Sequential Beamforming

    DEFF Research Database (Denmark)

    Kortbek, Jacob; Jensen, Jørgen Arendt; Gammelmark, Kim Løkke

    2008-01-01

    A synthetic aperture focusing (SAF) technique denoted Synthetic Aperture Sequential Beamforming (SASB) suitable for 2D and 3D imaging is presented. The technique differ from prior art of SAF in the sense that SAF is performed on pre-beamformed data contrary to channel data. The objective is to im......A synthetic aperture focusing (SAF) technique denoted Synthetic Aperture Sequential Beamforming (SASB) suitable for 2D and 3D imaging is presented. The technique differ from prior art of SAF in the sense that SAF is performed on pre-beamformed data contrary to channel data. The objective...... is to improve and obtain a more range independent lateral resolution compared to conventional dynamic receive focusing (DRF) without compromising frame rate. SASB is a two-stage procedure using two separate beamformers. First a set of Bmode image lines using a single focal point in both transmit and receive...... is stored. The second stage applies the focused image lines from the first stage as input data. The SASB method has been investigated using simulations in Field II and by off-line processing of data acquired with a commercial scanner. The performance of SASB with a static image object is compared with DRF...

  1. Generating User Interfaces with the FUSE-System

    OpenAIRE

    Frank Lonczewski; Siegfried Schreiber

    2017-01-01

    With the FUSE(Formal User interface Specification Environment)-System we present a methodology and a set of integrated tools for the automatic generation of graphical user interfaces. FUSE provides tool-based support for all phases (task-, user-, problem domain analysis, design of the logical user interface, design of user interface in a particular layout style) of the user interface development process. Based on a formal specification of dialogue- and layout guidelines, FUSE allows the autom...

  2. Change in silica sources in Roman and post-Roman glass

    International Nuclear Information System (INIS)

    Aerts, A.; Velde, B.; Janssens, K.; Dijkman, W.

    2003-01-01

    Although Roman and post-Empire glasses found in Europe are reputed to have a very constant composition and hence source of components, it appears that some 4-5th century and later specimens show evidence of a different source of silica (sand) component. Zirconium and titanium are the discriminating elements. Data presented here for 278 specimens from 1st to 4th century German and Belgian samples indicate a strongly homogeneous Zr and Ti content; N: number of analyzed samples while 62 samples from Maastricht show low Zr-Ti contents from 1st to 3rd century samples while 4-5th century samples show a strong trend of concomitant Ti and Zr increase. If the high values of Zr-Ti represent a new source of silica (sand) the trend from low to high content suggests that a significant amount of low Zr-Ti glass was recycled to form these glass objects. Similar high Ti content can be seen in analysis results reported for other but not all 4-5th century samples found in northern Europe while earlier productions show typical low Ti contents. Although the fusing agent for these glasses seems to have always been natron (a mineral deposit in the Nile delta) from Hellenistic times to the 9th century, a change in the silica source, indicated by variation of the Ti and Zr content, could very well reflect the results of political instability of the 4-5th century exemplified by the fragmentation of the Roman Empire into two parts

  3. Change in silica sources in Roman and post-Roman glass

    Energy Technology Data Exchange (ETDEWEB)

    Aerts, A.; Velde, B.; Janssens, K.; Dijkman, W

    2003-04-18

    Although Roman and post-Empire glasses found in Europe are reputed to have a very constant composition and hence source of components, it appears that some 4-5th century and later specimens show evidence of a different source of silica (sand) component. Zirconium and titanium are the discriminating elements. Data presented here for 278 specimens from 1st to 4th century German and Belgian samples indicate a strongly homogeneous Zr and Ti content; N: number of analyzed samples while 62 samples from Maastricht show low Zr-Ti contents from 1st to 3rd century samples while 4-5th century samples show a strong trend of concomitant Ti and Zr increase. If the high values of Zr-Ti represent a new source of silica (sand) the trend from low to high content suggests that a significant amount of low Zr-Ti glass was recycled to form these glass objects. Similar high Ti content can be seen in analysis results reported for other but not all 4-5th century samples found in northern Europe while earlier productions show typical low Ti contents. Although the fusing agent for these glasses seems to have always been natron (a mineral deposit in the Nile delta) from Hellenistic times to the 9th century, a change in the silica source, indicated by variation of the Ti and Zr content, could very well reflect the results of political instability of the 4-5th century exemplified by the fragmentation of the Roman Empire into two parts.

  4. Change in silica sources in Roman and post-Roman glass

    Science.gov (United States)

    Aerts, A.; Velde, B.; Janssens, K.; Dijkman, W.

    2003-04-01

    Although Roman and post-Empire glasses found in Europe are reputed to have a very constant composition and hence source of components, it appears that some 4-5th century and later specimens show evidence of a different source of silica (sand) component. Zirconium and titanium are the discriminating elements. Data presented here for 278 specimens from 1st to 4th century German and Belgian samples indicate a strongly homogeneous Zr and Ti content; N: number of analyzed samples while 62 samples from Maastricht show low Zr-Ti contents from 1st to 3rd century samples while 4-5th century samples show a strong trend of concomitant Ti and Zr increase. If the high values of Zr-Ti represent a new source of silica (sand) the trend from low to high content suggests that a significant amount of low Zr-Ti glass was recycled to form these glass objects. Similar high Ti content can be seen in analysis results reported for other but not all 4-5th century samples found in northern Europe while earlier productions show typical low Ti contents. Although the fusing agent for these glasses seems to have always been natron (a mineral deposit in the Nile delta) from Hellenistic times to the 9th century, a change in the silica source, indicated by variation of the Ti and Zr content, could very well reflect the results of political instability of the 4-5th century exemplified by the fragmentation of the Roman Empire into two parts.

  5. 30 CFR 56.12036 - Fuse removal or replacement.

    Science.gov (United States)

    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... § 56.12036 Fuse removal or replacement. Fuses shall not be removed or replaced by hand in an energized...

  6. Data Fusion and Fuzzy Clustering on Ratio Images for Change Detection in Synthetic Aperture Radar Images

    Directory of Open Access Journals (Sweden)

    Wenping Ma

    2014-01-01

    Full Text Available The unsupervised approach to change detection via synthetic aperture radar (SAR images becomes more and more popular. The three-step procedure is the most widely used procedure, but it does not work well with the Yellow River Estuary dataset obtained by two synthetic aperture radars. The difference of the two radars in imaging techniques causes severe noise, which seriously affects the difference images generated by a single change detector in step two, producing the difference image. To deal with problem, we propose a change detector to fuse the log-ratio (LR and the mean-ratio (MR images by a context independent variable behavior (CIVB operator and can utilize the complement information in two ratio images. In order to validate the effectiveness of the proposed change detector, the change detector will be compared with three other change detectors, namely, the log-ratio (LR, mean-ratio (MR, and the wavelet-fusion (WR operator, to deal with three datasets with different characteristics. The four operators are applied not only in a widely used three-step procedure but also in a new approach. The experiments show that the false alarms and overall errors of change detection are greatly reduced, and the kappa and KCC are improved a lot. And its superiority can also be observed visually.

  7. Facile preparation of organic-silica hybrid monolith for capillary hydrophilic liquid chromatography based on "thiol-ene" click chemistry.

    Science.gov (United States)

    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. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. Silica Nephropathy

    Directory of Open Access Journals (Sweden)

    N Ghahramani

    2010-06-01

    Full Text Available Occupational exposure to heavy metals, organic solvents and silica is associated with a variety of renal manifestations. Improved understanding of occupational renal disease provides insight into environmental renal disease, improving knowledge of disease pathogenesis. Silica (SiO2 is an abundant mineral found in sand, rock, and soil. Workers exposed to silica include sandblasters, miners, quarry workers, masons, ceramic workers and glass manufacturers. New cases of silicosis per year have been estimated in the US to be 3600–7300. Exposure to silica has been associated with tubulointerstitial disease, immune-mediated multisystem disease, chronic kidney disease and end-stage renal disease. A rare syndrome of painful, nodular skin lesions has been described in dialysis patients with excessive levels of silicon. Balkan endemic nephropathy is postulated to be due to chronic intoxication with drinking water polluted by silicates released during soil erosion. The mechanism of silica nephrotoxicity is thought to be through direct nephrotoxicity, as well as silica-induced autoimmune diseases such as scleroderma and systemic lupus erythematosus. The renal histopathology varies from focal to crescentic and necrotizing glomerulonephritis with aneurysm formation suggestive of polyarteritis nodosa. The treatment for silica nephrotoxicity is non-specific and depends on the mechanism and stage of the disease. It is quite clear that further research is needed, particularly to elucidate the pathogenesis of silica nephropathy. Considering the importance of diagnosing exposure-related renal disease at early stages, it is imperative to obtain a thorough occupational history in all patients with renal disease, with particular emphasis on exposure to silica, heavy metals, and solvents.

  9. Filled aperture concepts for the Terrestrial Planet Finder

    Science.gov (United States)

    Ridgway, Stephen T.

    2003-02-01

    Filled aperture telescopes can deliver a real, high Strehl image which is well suited for discrimination of faint planets in the vicinity of bright stars and against an extended exo-zodiacal light. A filled aperture offers a rich variety of PSF control and diffraction suppression techniques. Filled apertures are under consideration for a wide spectral range, including visible and thermal-IR, each of which offers a significant selection of biomarker molecular bands. A filled aperture visible TPF may be simpler in several respects than a thermal-IR nuller. The required aperture size (or baseline) is much smaller, and no cryogenic systems are required. A filled aperture TPF would look and act like a normal telescope - vendors and users alike would be comfortable with its design and operation. Filled aperture telescopes pose significant challenges in production of large primary mirrors, and in very stringent wavefront requirements. Stability of the wavefront control, and hence of the PSF, is a major issue for filled aperture systems. Several groups have concluded that these and other issues can be resolved, and that filled aperture options are competitive for a TPF precursor and/or for the full TPF mission. Ball, Boeing-SVS and TRW have recently returned architecture reviews on filled aperture TPF concepts. In this paper, I will review some of the major considerations underlying these filled aperture concepts, and suggest key issues in a TPF Buyers Guide.

  10. 30 CFR 57.6502 - Safety fuse.

    Science.gov (United States)

    2010-07-01

    ... blasthole detonates. (d) Fuse shall be cut and capped in dry locations. (e) Blasting caps shall be crimped... the primer and the explosive material are securely in place. (g) Safety fuse shall be ignited only... to be fired, electric initiation systems, igniter cord and connectors, or other nonelectric...

  11. 30 CFR 56.6502 - Safety fuse.

    Science.gov (United States)

    2010-07-01

    ... be cut and capped in dry locations. (e) Blasting caps shall be crimped to fuse only with implements... material are securely in place. (g) Safety fuse shall be ignited only with devices designed for that... initiation systems, igniter cord and connectors, or other nonelectric initiation systems shall be used...

  12. Palladium–zinc catalysts on mesoporous titania prepared by colloid synthesis. II. Synthesis and characterization of PdZn/TiO2 coating on inner surface of fused silica capillary

    International Nuclear Information System (INIS)

    Okhlopkova, Lyudmila B.; Kerzhentsev, Michail A.; Tuzikov, Fedor V.; Larichev, Yurii V.; Ismagilov, Zinfer R.

    2012-01-01

    Nanoparticle-doped mesoporous titania coating was synthesized by incorporation of PdZn nanoparticles into TiO 2 sol followed by dip coating of the sol on inner surface of fused silica capillary. Monodispersed PdZn bimetallic colloidal particles with average particle diameters of approximately 2 nm have been prepared by an ethylene glycol reduction of ZnCl 2 and Pd(CH 3 COO) 2 in the presence of polyvinylpyrrolidone. The textural properties, surface structure, chemical composition, and morphology of the samples were investigated by means of N 2 sorption measurements, TEM, and X-ray diffraction. PdZn/TiO 2 coating has been further analyzed by quantitative analysis of the SAXS data in combination with the density contrast method, providing direct structural-dispersion information about the active component and support. Calcination conditions suitable for surfactant removal have been optimized to obtain PdZn/TiO 2 coatings with required metal particle size and composition. The high dispersion and chemical composition of the nanoparticles embedded in mesoporous titania coating have been retained with no modification after thermal treatment in vacuum at 300 °C. Results suggest how porous structure of the PdZn coating may be fine-tuned to improve the accessibility of the pores to reactants. The control of the pore size in the range of 4.9–6.8 nm of the mesoporous titania was achieved by adding co-surfactants, such as n-butanol.

  13. Planar and channel waveguides in fused silica fabricated by multi-energy C ion in the visible and near-infrared band

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Tao; Huang, Qing; Liu, Peng; Guo, Sha-Sha; Zhang, Lian; Zhou, Yu-Fan [School of Physics, State Key Laboratory of Crystal Materials and Key Laboratory of Particle Physics and Particle Irradiation (MOE), Shandong University, Jinan 250100 (China); Wang, Xue-Lin, E-mail: xuelinwang@sdu.edu.cn [School of Physics, State Key Laboratory of Crystal Materials and Key Laboratory of Particle Physics and Particle Irradiation (MOE), Shandong University, Jinan 250100 (China)

    2013-07-15

    Fused quartz is a key material in fabrication of integrated devices, which transmits extends from ultraviolet to infrared. We report the fabrication of planar and channel waveguides in fused quartz using multi-energy C ion at energies of (5 + 5.5 + 6) MeV and fluences of (1 + 1 + 1.5) × 10{sup 15} ions/cm{sup 2}. The guiding modes at the wavelength of 633 nm (He–Ne laser) and 1539 nm (diode laser) were detected using the prism-coupling method, and the modes were stable after annealing in air. The refractive index profiles of planar and channel waveguides at the wavelength of 633 nm and 1539 nm were typical “well + barrier” distributions, which were reconstructed using the reflectivity calculation method (RCM) software and intensity calculation method (ICM), respectively. For comparison to the experimental results, the finite difference beam propagation method (FD-BPM) was used to simulate the guiding modes of the waveguides. We measured the near-field intensity distributions for the visible (633 nm) and near-infrared (1300 nm, 1539 nm and 1620 nm) wavelength regions, suggesting that the modes can be effective transmission in the wavelength range for optical fiber communications.

  14. Measurements of pore-scale flow through apertures

    Energy Technology Data Exchange (ETDEWEB)

    Chojnicki, Kirsten [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-09-01

    Pore-scale aperture effects on flow in pore networks was studied in the laboratory to provide a parameterization for use in transport models. Four cases were considered: regular and irregular pillar/pore alignment with and without an aperture. The velocity field of each case was measured and simulated, providing quantitatively comparable results. Two aperture effect parameterizations were considered: permeability and transmission. Permeability values varied by an order of magnitude between the cases with and without apertures. However, transmission did not correlate with permeability. Despite having much greater permeability the regular aperture case permitted less transmission than the regular case. Moreover, both irregular cases had greater transmission than the regular cases, a difference not supported by the permeabilities. Overall, these findings suggest that pore-scale aperture effects on flow though a pore-network may not be adequately captured by properties such as permeability for applications that are interested in determining particle transport volume and timing.

  15. Mobile, hybrid Compton/coded aperture imaging for detection, identification and localization of gamma-ray sources at stand-off distances

    Science.gov (United States)

    Tornga, Shawn R.

    The Stand-off Radiation Detection System (SORDS) program is an Advanced Technology Demonstration (ATD) project through the Department of Homeland Security's Domestic Nuclear Detection Office (DNDO) with the goal of detection, identification and localization of weak radiological sources in the presence of large dynamic backgrounds. The Raytheon-SORDS Tri-Modal Imager (TMI) is a mobile truck-based, hybrid gamma-ray imaging system able to quickly detect, identify and localize, radiation sources at standoff distances through improved sensitivity while minimizing the false alarm rate. Reconstruction of gamma-ray sources is performed using a combination of two imaging modalities; coded aperture and Compton scatter imaging. The TMI consists of 35 sodium iodide (NaI) crystals 5x5x2 in3 each, arranged in a random coded aperture mask array (CA), followed by 30 position sensitive NaI bars each 24x2.5x3 in3 called the detection array (DA). The CA array acts as both a coded aperture mask and scattering detector for Compton events. The large-area DA array acts as a collection detector for both Compton scattered events and coded aperture events. In this thesis, developed coded aperture, Compton and hybrid imaging algorithms will be described along with their performance. It will be shown that multiple imaging modalities can be fused to improve detection sensitivity over a broader energy range than either alone. Since the TMI is a moving system, peripheral data, such as a Global Positioning System (GPS) and Inertial Navigation System (INS) must also be incorporated. A method of adapting static imaging algorithms to a moving platform has been developed. Also, algorithms were developed in parallel with detector hardware, through the use of extensive simulations performed with the Geometry and Tracking Toolkit v4 (GEANT4). Simulations have been well validated against measured data. Results of image reconstruction algorithms at various speeds and distances will be presented as well as

  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

    Science.gov (United States)

    Wang, X.; Chou, I-Ming; Hu, W.; Burruss, Robert; 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 (Δ, cm−1) and CO2 density (ρ, 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 CO2fluids having densities between 0.21 and 0.75 g/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 1.0060 g/cm3. The measured CO2 Fermi diad splits were calibrated with two well established Raman bands of benzonitrile at 1192.6 and 1598.9 cm−1. The relationship between the CO2 Fermi diad split and density can be represented by: ρ = 47513.64243 − 1374.824414 × Δ + 13.25586152 × Δ2 − 0.04258891551 × Δ3(r2 = 0.99835, σ = 0.0253 g/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.

  17. Some Durability Characteristics of Micro Silica and Nano Silica Contained Concrete

    Directory of Open Access Journals (Sweden)

    Mohammed Salah Nasr

    2016-12-01

    Full Text Available This paper aims to investigate the influence of replacement of cement with nano and micro silica admixtures on some durability properties of concrete such as water absorption, chloride content and pH tests. Three replacement ratios (5%,10%,15% of micro silica and four replacement proportions (0.5%,1.5%,3%,5% for nano silica were used in this study. Two exposure conditions were considered for chloride content test: wetting-drying and full immersing exposure in 6% of chloride ions solution, NaCl type. Results showed that mixes of %5 micro silica and 5% nano silica had lower content of chloride (about 0.19% and 0.18% for wetting-drying and full immersing exposure respectively. For water absorption test, all mixes incorporated micro and nano silica, except for %5 micro silica mix, showed lower absorption than control mixes. For pH test, results indicated that the adding of nano and micro silica didn’t affect adversely the alkalinity of concrete.

  18. Fused aromatic thienopyrazines: structure, properties and function

    KAUST Repository

    Mondal, Rajib; Ko, Sangwon; Bao, Zhenan

    2010-01-01

    Recent development of a fused aromatic thieno[3.4-b]pyrazine system and their application in optoelectronic devices are reviewed. Introduction of a fused aromatic unit followed by side chain engineering, dramatically enhanced the charge carrier

  19. Reactive silica transport in fractured porous media: Analytical solutions for a system of parallel fractures

    Science.gov (United States)

    Yang, Jianwen

    2012-04-01

    A general analytical solution is derived by using the Laplace transformation to describe transient reactive silica transport in a conceptualized 2-D system involving a set of parallel fractures embedded in an impermeable host rock matrix, taking into account of hydrodynamic dispersion and advection of silica transport along the fractures, molecular diffusion from each fracture to the intervening rock matrix, and dissolution of quartz. A special analytical solution is also developed by ignoring the longitudinal hydrodynamic dispersion term but remaining other conditions the same. The general and special solutions are in the form of a double infinite integral and a single infinite integral, respectively, and can be evaluated using Gauss-Legendre quadrature technique. A simple criterion is developed to determine under what conditions the general analytical solution can be approximated by the special analytical solution. It is proved analytically that the general solution always lags behind the special solution, unless a dimensionless parameter is less than a critical value. Several illustrative calculations are undertaken to demonstrate the effect of fracture spacing, fracture aperture and fluid flow rate on silica transport. The analytical solutions developed here can serve as a benchmark to validate numerical models that simulate reactive mass transport in fractured porous media.

  20. Research on high-efficiency polishing technology of photomask substrate

    Science.gov (United States)

    Zhao, Shijie; Xie, Ruiqing; Zhou, Lian; Liao, Defeng; Chen, Xianhua; Wang, Jian

    2018-03-01

    A method of photomask substrate fabrication is demonstrated ,that the surface figure and roughness of fused silica will converge to target precision rapidly with the full aperture polishing. Surface figure of optical flats in full aperture polishing processes is primarily dependent on the surface profile of polishing pad, therefor, a improved function of polishing mechanism was put forward based on two axis lapping machine and technology experience, and the pad testing based on displacement sensor and the active conditioning method of the pad is applied in this research. Moreover , the clamping deformation of the thin glass is solved by the new pitch dispensing method. The experimental results show that the surface figure of the 152mm×152mm×6.35mm optical glass is 0.25λ(λ=633nm) and the roughness is 0.32nm ,which has meet the requirements of mask substrate for 90 45nm nodes.

  1. Calibration of the TUD Ku-band Synthetic Aperture Radiometer

    DEFF Research Database (Denmark)

    Laursen, Brian; Skou, Niels

    1995-01-01

    The TUD Synthetic Aperture Radiometer is a 2-channel demonstration model that can simulate a thinned aperture radiometer having an unfilled aperture consisting of several small antenna elements. Aperture synthesis obtained by interferometric measurements using the antenna elements in pairs, follo...

  2. Microporous silica membranes

    DEFF Research Database (Denmark)

    Boffa, Vittorio; Yue, Yuanzheng

    2012-01-01

    Hydrothermal stability is a crucial factor for the application of microporous silica-based membranes in industrial processes. Indeed, it is well established that steam exposure may cause densification and defect formation in microporous silica membranes, which are detrimental to both membrane...... permeability and selectivity. Numerous previous studies show that microporous transition metal doped-silica membranes are hydrothermally more stable than pure silica membranes, but less permeable. Here we present a quantitative study on the impact of type and concentration of transition metal ions...... on the microporous structure, stability and permeability of amorphous silica-based membranes, providing information on how to design chemical compositions and synthetic paths for the fabrication of silica-based membranes with a well accessible and highly stabile microporous structure....

  3. Beam aperture modifier design with acoustic metasurfaces

    Science.gov (United States)

    Tang, Weipeng; Ren, Chunyu

    2017-10-01

    In this paper, we present a design concept of acoustic beam aperture modifier using two metasurface-based planar lenses. By appropriately designing the phase gradient profile along the metasurface, we obtain a class of acoustic convex lenses and concave lenses, which can focus the incoming plane waves and collimate the converging waves, respectively. On the basis of the high converging and diverging capability of these lenses, two kinds of lens combination scheme, including the convex-concave type and convex-convex type, are proposed to tune up the incoming beam aperture as needed. To be specific, the aperture of the acoustic beam can be shrunk or expanded through adjusting the phase gradient of the pair of lenses and the spacing between them. These lenses and the corresponding aperture modifiers are constructed by the stacking ultrathin labyrinthine structures, which are obtained by the geometry optimization procedure and exhibit high transmission coefficient and a full range of phase shift. The simulation results demonstrate the effectiveness of our proposed beam aperture modifiers. Due to the flexibility in aperture controlling and the simplicity in fabrication, the proposed modifiers have promising potential in applications, such as acoustic imaging, nondestructive evaluation, and communication.

  4. Fuse Modeling for Reliability Study of Power Electronic Circuits

    DEFF Research Database (Denmark)

    Bahman, Amir Sajjad; Iannuzzo, Francesco; Blaabjerg, Frede

    2017-01-01

    This paper describes a comprehensive modeling approach on reliability of fuses used in power electronic circuits. When fuses are subjected to current pulses, cyclic temperature stress is introduced to the fuse element and will wear out the component. Furthermore, the fuse may be used in a large......, and rated voltage/current are opposed to shift in time to effect early breaking during the normal operation of the circuit. Therefore, in such cases, a reliable protection required for the other circuit components will not be achieved. The thermo-mechanical models, fatigue analysis and thermo...

  5. Ion mobility spectrometer with virtual aperture grid

    Science.gov (United States)

    Pfeifer, Kent B.; Rumpf, Arthur N.

    2010-11-23

    An ion mobility spectrometer does not require a physical aperture grid to prevent premature ion detector response. The last electrodes adjacent to the ion collector (typically the last four or five) have an electrode pitch that is less than the width of the ion swarm and each of the adjacent electrodes is connected to a source of free charge, thereby providing a virtual aperture grid at the end of the drift region that shields the ion collector from the mirror current of the approaching ion swarm. The virtual aperture grid is less complex in assembly and function and is less sensitive to vibrations than the physical aperture grid.

  6. Optically driven self-oscillations of a silica nanospike at low gas pressures

    Science.gov (United States)

    Xie, Shangran; Pennetta, Riccardo; Noskov, Roman E.; Russell, Philip St. J.

    2016-09-01

    We report light-driven instability and optomechanical self-oscillation of a fused silica "nanospike" at low gas pressures. The nanospike (tip diameter 400 nm), fabricated by thermally tapering and HF-etching a single mode fiber (SMF), was set pointing at the endface of a hollow-core photonic crystal fiber (HC-PCF) into the field created by the fundamental optical mode emerging from the HC-PCF. At low pressures, the nanospike became unstable and began to self-oscillate for optical powers above a certain threshold, acting like a phonon laser or "phaser". Because the nanospike is robustly connected to the base, direct measurement of the temporal dynamics of the instability is possible. The experiment sheds light on why particles escape from optical traps at low pressures.

  7. Crystalline Silica Primer

    Science.gov (United States)

    ,

    1992-01-01

    Crystalline silica is the scientific name for a group of minerals composed of silicon and oxygen. The term crystalline refers to the fact that the oxygen and silicon atoms are arranged in a threedimensional repeating pattern. This group of minerals has shaped human history since the beginning of civilization. From the sand used for making glass to the piezoelectric quartz crystals used in advanced communication systems, crystalline silica has been a part of our technological development. Crystalline silica's pervasiveness in our technology is matched only by its abundance in nature. It's found in samples from every geologic era and from every location around the globe. Scientists have known for decades that prolonged and excessive exposure to crystalline silica dust in mining environments can cause silicosis, a noncancerous lung disease. During the 1980's, studies were conducted that suggested that crystalline silica also was a carcinogen. As a result of these findings, crystalline silica has been regulated under the Occupational Safety and Health Administration's (OSHA) Hazard Communication Standard (HCS). Under HCS, OSHAregulated businesses that use materials containing 0.1% or more crystalline silica must follow Federal guidelines concerning hazard communication and worker training. Although the HCS does not require that samples be analyzed for crystalline silica, mineral suppliers or OSHAregulated

  8. Imaging with rotating slit apertures and rotating collimators

    International Nuclear Information System (INIS)

    Gindi, G.R.; Arendt, J.; Barrett, H.H.; Chiu, M.Y.; Ervin, A.; Giles, C.L.; Kujoory, M.A.; Miller, E.L.; Simpson, R.G.

    1982-01-01

    The statistical quality of conventional nuclear medical imagery is limited by the small signal collect through low-efficiency conventional apertures. Coded-aperture imaging overcomes this by employing a two-step process in which the object is first efficiently detected as an ''encoded'' form which does not resemble the object, and then filtered (or ''decoded'') to form an image. We present here the imaging properties of a class of time-modulated coded apertures which, unlike most coded apertures, encode projections of the object rather than the object itself. These coded apertures can reconstruct a volume object nontomographically, tomographically (one plane focused), or three-dimensionally. We describe a new decoding algorithm that reconstructs the object from its planar projections. Results of noise calculations are given, and the noise performance of these coded-aperture systems is compared to that of conventional counterparts. A hybrid slit-pinhole system which combines the imaging advantages of a rotating slit and a pinhole is described. A new scintillation detector which accurately measures the position of an event in one dimension only is presented, and its use in our coded-aperture system is outlined. Finally, results of imaging test objects and animals are given

  9. Imaging with rotating slit apertures and rotating collimators

    International Nuclear Information System (INIS)

    Gindi, G.R.; Arendt, J.; Barrett, H.H.; Chiu, M.Y.; Ervin, A.; Giles, C.L.; Kujoory, M.A.; Miller, E.L.; Simpson, R.G.

    1982-01-01

    The statistical quality of conventional nuclear medical imagery is limited by the small signal collected through low-efficiency conventional apertures. Coded-aperture imaging overcomes this by employing a two-step process in which the object is first efficiently detected as an encoded form which does not resemble the object, and then filtered (or decoded) to form an image. We present here the imaging properties of a class of time-modulated coded apertures which, unlike most coded apertures, encode projections of the object rather than the object itself. These coded apertures can reconstruct a volume object nontomographically, tomographically (one plane focused), or three-dimensionally. We describe a new decoding algorithm that reconstructs the object from its planar projections. Results of noise calculations are given, and the noise performance of these coded-aperture systems is compared to that of conventional counterparts. A hybrid slit-pinhole system which combines the imaging advantages of a rotating slit and a pinhole is described. A new scintillation detector which accurately measures the position of an event in one dimension only is presented, and its use in our coded-aperture system is outlined. Finally, results of imaging test objects and animals are given

  10. Influence of System Parameters on Fuse Protection Use in Regenerative DC Drives

    Directory of Open Access Journals (Sweden)

    Isa Salman Qamber

    2009-06-01

    Full Text Available Current limiting fuses are widely used to protect the thyristors in DC drive systems. One very important problem is the choice of the correct voltage rating for fuses protecting regenerative DC drives, where many types of fault may occur, which makes fuse protection difficult. In the event of a commutation failure while regenerating, the fuses need to interrupt the loop supplied by the AC and DC voltages acting in series, which is the most difficult case for protection by fuses. In this paper a detailed study of the complete interruption process has been investigated by modeling of arcing process of the fuse protection against the regenerative circuit internal commutation fault. The effect of varying the motor time constant, supply impedance, number of fuses used to clear the fault and DC machine rating on the total transient response is studied. The model of a 200 A fuse is employed in this study. Fuses in series with both the semiconductor devices (F1 and fuses in AC lines (F2 are considered. Comparison was made between arc energy produced for fuses protecting the regenerative circuit if failure occurs, with the arc energy produced in a standard AC test in order to investigate the required voltage rating for the fuse.

  11. Microfabricated high-bandpass foucault aperture for electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Glaeser, Robert; Cambie, Rossana; Jin, Jian

    2014-08-26

    A variant of the Foucault (knife-edge) aperture is disclosed that is designed to provide single-sideband (SSB) contrast at low spatial frequencies but retain conventional double-sideband (DSB) contrast at high spatial frequencies in transmission electron microscopy. The aperture includes a plate with an inner open area, a support extending from the plate at an edge of the open area, a half-circle feature mounted on the support and located at the center of the aperture open area. The radius of the half-circle portion of reciprocal space that is blocked by the aperture can be varied to suit the needs of electron microscopy investigation. The aperture is fabricated from conductive material which is preferably non-oxidizing, such as gold, for example.

  12. Beam focusing by aperture displacement in multiampere ion sources

    International Nuclear Information System (INIS)

    Stewart, L.D.; Kim, J.; Matsuda, S.

    1975-05-01

    Results are given of an experimental study of beam focusing by aperture displacement (Δx) in duoPIGatron ion sources. Measurements with a single aperture, accel-decel electrode geometry show that the beam deflection angle is linear with Δx/z for the round aperture and with Δx/z* 2 for the slit aperture where z and z* are respectively the extraction gap distance and the effective gap distance. Applying the result of the single aperture study to the multiaperture, duoPIGatron sources, it was possible to increase the neutral beam injection power to the ORMAK plasma by approximately 40 percent. Also presented are discussion and comparison of other work on the effect of aperture displacement on beam deflection. (U.S.)

  13. Fused aromatic thienopyrazines: structure, properties and function

    KAUST Repository

    Mondal, Rajib

    2010-01-01

    Recent development of a fused aromatic thieno[3.4-b]pyrazine system and their application in optoelectronic devices are reviewed. Introduction of a fused aromatic unit followed by side chain engineering, dramatically enhanced the charge carrier mobility in thin film transistor devices and mobilities up to 0.2 cm2/Vs were achieved. The optoelectronic properties of these fused aromatic thienopyrazine polymers (Eg = 1.3 to 1.6 eV, HOMO = -4.9 to -5.2 V) were tuned by introduction of various fused aromatic rings within thienopyrazine. By balancing the fundamental properties of these polymers, both high charge carrier mobilities and moderate PCEs in solar cells were achieved. Further, effects of copolymerizing units are discussed. Low band gap semiconducting polymer (Eg ∼ 1 eV) with high field effect mobility (0.044 cm2/Vs) was obtained using cyclopentadithiophene as copolymerizing unit. Finally, a molecular design approach to enhance the absorption coefficients is discussed, which resulted in improved power conversion efficiency in bulk heterojunction solar cells. © 2010 The Royal Society of Chemistry.

  14. Functional Use Database (FUse)

    Data.gov (United States)

    U.S. Environmental Protection Agency — There are five different files for this dataset: 1. A dataset listing the reported functional uses of chemicals (FUse) 2. All 729 ToxPrint descriptors obtained from...

  15. Field measurements for low-aperture magnetic elements

    International Nuclear Information System (INIS)

    Mikhajlichenko, A.A.

    1989-01-01

    The method of the field measurements with help of bismuth wire in low aperture magnetic elements is revised. The quadrupole with permanent magnets was tested. It has aperture diameter about 4 mm and length 40 mm. Gradient about 38 kOe/cm was measured. The accuracy of the magnetic axis position definition is better than 1 μm. This method is a good kandidate for linear colider low aperture magnetic elements measurements. 7 refs.; 6 figs

  16. Fast decoding algorithms for geometric coded apertures

    International Nuclear Information System (INIS)

    Byard, Kevin

    2015-01-01

    Fast decoding algorithms are described for the class of coded aperture designs known as geometric coded apertures which were introduced by Gourlay and Stephen. When compared to the direct decoding method, the algorithms significantly reduce the number of calculations required when performing the decoding for these apertures and hence speed up the decoding process. Experimental tests confirm the efficacy of these fast algorithms, demonstrating a speed up of approximately two to three orders of magnitude over direct decoding.

  17. Microstructure investigation on micropore formation in microporous silica materials prepared via a catalytic sol-gel process by small angle X-ray scattering.

    Science.gov (United States)

    Shimizu, Wataru; Hokka, Junsuke; Sato, Takaaki; Usami, Hisanao; Murakami, Yasushi

    2011-08-04

    The so-called sol-gel technique has been shown to be a template-free, efficient way to create functional porous silica materials having uniform micropores. This appears to be closely linked with a postulation that the formation of weakly branched polymer-like aggregates in a precursor solution is a key to the uniform micropore generation. However, how such a polymer-like structure can precisely be controlled, and further, how the generated low-fractal dimension solution structure is imprinted on the solid silica materials still remain elusive. Here we present fabrication of microporous silica from tetramethyl orthosilicate (TMOS) using a recently developed catalytic sol-gel process based on a nonionic hydroxyacetone (HA) catalyst. Small angle X-ray scattering (SAXS), nitrogen adsorption porosimetry, and transmission electron microscope (TEM) allowed us to observe the whole structural evolution, ranging from polymer-like aggregates in the precursor solution to agglomeration with heat treatment and microporous morphology of silica powders after drying and hydrolysis. Using the HA catalyst with short chain monohydric alcohols (methanol or ethanol) in the precursor solution, polymer-like aggregates having microscopic correlation length (or mesh-size) micropores with diameters 2 nm) in the solid product due to apertures between the particle-like aggregates. The data demonstrate that the extremely fine porous silica architecture comes essentially from a gaussian polymer-like nature of the silica aggregates in the precursor having the microscopic mesh-size and their successful imprint on the solid product. The result offers a general but significantly efficient route to creating precisely designed fine porous silica materials under mild condition that serve as low refractive index and efficient thermal insulation materials in their practical applications.

  18. 29 CFR 1926.907 - Use of safety fuse.

    Science.gov (United States)

    2010-07-01

    ... way shall be forbidden. (b) The hanging of a fuse on nails or other projections which will cause a...-called “drop fuse” method of dropping or pushing a primer or any explosive with a lighted fuse attached...

  19. Dedication for Safety-Related Fuses used in Class-1E Power System

    International Nuclear Information System (INIS)

    Hong, Younghee

    2014-01-01

    The safety-related fuses used in class-1E power system provide overcurrent protection for electrical system and isolate the class 1E circuit from a fault or overload condition. These days, the number of nuclear grade suppliers has been reduced. Accordingly, commercial grade, instead of safety-related, fuses are procured and used in the utilities through the dedication process. Therefore, this paper introduces the commercial grade fuse dedication process/engineering and how to assure the quality requirements with this process and engineering. The fuses used in class-1E power system are to protect overcurrent and to isolate fault. Therefore the fuse for acceptance in order to improve the quality and reliability for commercial grade fuses shall be dedicated. The fuse resistance value may be useful as an indicator of acceptance. The current carrying capacity test can change the fuse performance properties. Therefore these critical characteristics are needed for additional review and analysis with fuse manufactures

  20. Temperature dependence of luminescence for different surface flaws in high purity silica glass

    International Nuclear Information System (INIS)

    Fournier, J.; Grua, P.; Neauport, J.; Fargin, E.; Jubera, V.; Talaga, D.; Del Guerzo, A.; Raffy, G.; Jouannigot, S.

    2013-01-01

    In situ temperature dependence of the Photoluminescence under 325 nm irradiation is used to investigate defect populations existing in different surface flaws in high purity fused silica. Five photoluminescence bands peaking at 1.9, 2.1, 2.3, 2.63 and 3.11 eV have been detected in the spectral area ranging from 1.6 up to 3.6 eV. The Gaussian deconvolution of spectra allows dividing the five luminescence bands in two categories. The former corresponds to bands showing a significant intensity enhancement while temperature decreases; the latter corresponds to bands remaining insensitive to the temperature evolution. Such a behavior brings new information on defects involved in laser damage mechanism at 351 nm in nanosecond regime. (authors)

  1. Silica coated ionic liquid templated mesoporous silica nanoparticles ...

    African Journals Online (AJOL)

    A series of long chain pyridinium based ionic liquids 1-tetradecylpyridinium bromide, 1-hexadecylpyridinium bromide and 1-1-octadecylpyridinium bromide were used as templates to prepare silica coated mesoporous silica nanoparticles via condensation method under basic condition. The effects of alkyl chain length on ...

  2. Dual aperture dipole magnet with second harmonic component

    Science.gov (United States)

    Praeg, Walter F.

    1985-01-01

    An improved dual aperture dipole electromagnet includes a second-harmonic frequency magnetic guide field winding which surrounds first harmonic frequency magnetic guide field windings associated with each aperture. The second harmonic winding and the first harmonic windings cooperate to produce resultant magnetic waveforms in the apertures which have extended acceleration and shortened reset portions of electromagnet operation.

  3. 47 CFR 25.134 - Licensing provisions of Very Small Aperture Terminal (VSAT) and C-band Small Aperture Terminal...

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Licensing provisions of Very Small Aperture Terminal (VSAT) and C-band Small Aperture Terminal (CSAT) networks. 25.134 Section 25.134 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES SATELLITE COMMUNICATIONS...

  4. Transport of Particle Swarms Through Variable Aperture Fractures

    Science.gov (United States)

    Boomsma, E.; Pyrak-Nolte, L. J.

    2012-12-01

    Particle transport through fractured rock is a key concern with the increased use of micro- and nano-size particles in consumer products as well as from other activities in the sub- and near surface (e.g. mining, industrial waste, hydraulic fracturing, etc.). While particle transport is often studied as the transport of emulsions or dispersions, particles may also enter the subsurface from leaks or seepage that lead to particle swarms. Swarms are drop-like collections of millions of colloidal-sized particles that exhibit a number of unique characteristics when compared to dispersions and emulsions. Any contaminant or engineered particle that forms a swarm can be transported farther, faster, and more cohesively in fractures than would be expected from a traditional dispersion model. In this study, the effects of several variable aperture fractures on colloidal swarm cohesiveness and evolution were studied as a swarm fell under gravity and interacted with the fracture walls. Transparent acrylic was used to fabricate synthetic fracture samples with (1) a uniform aperture, (2) a converging region followed by a uniform region (funnel shaped), (3) a uniform region followed by a diverging region (inverted funnel), and (4) a cast of a an induced fracture from a carbonate rock. All of the samples consisted of two blocks that measured 100 x 100 x 50 mm. The minimum separation between these blocks determined the nominal aperture (0.5 mm to 20 mm). During experiments a fracture was fully submerged in water and swarms were released into it. The swarms consisted of a dilute suspension of 3 micron polystyrene fluorescent beads (1% by mass) with an initial volume of 5μL. The swarms were illuminated with a green (525 nm) LED array and imaged optically with a CCD camera. The variation in fracture aperture controlled swarm behavior. Diverging apertures caused a sudden loss of confinement that resulted in a rapid change in the swarm's shape as well as a sharp increase in its velocity

  5. Fractal characteristics of fracture roughness and aperture data

    International Nuclear Information System (INIS)

    Kumar, S.; Boernge, J.

    1991-05-01

    In this study mathematical expressions are developed for the characteristics of apertures between rough surfaces. It has shown that the correlation between the opposite surfaces influences the aperture properties and different models are presented for these different surface correlations. Fracture and apertures profiles measured from intact fractures are evaluated and it is found that they qualitatively follow the mathematically predicted trends

  6. Calibration of circular aperture area using vision probe at inmetro

    Directory of Open Access Journals (Sweden)

    Costa Pedro Bastos

    2016-01-01

    Full Text Available Circular aperture areas are standards of high importance for the realization of photometric and radiometric measurements, where the accuracy of these measures is related to the accuracy of the circular aperture area calibrations. In order to attend the requirement for traceability was developed in Brazilian metrology institute, a methodology for circular aperture area measurement as requirements from the radiometric and photometric measurements. In the developed methodology apertures are measured by non-contact measurement through images of the aperture edges captured by a camera. These images are processed using computer vision techniques and then the values of the circular aperture area are determined.

  7. Synthetic aperture radar: principles and applications

    International Nuclear Information System (INIS)

    Khan, N.A.; Yahya, K.M.

    2003-01-01

    In this paper an introduction to synthetic aperture radar is presented. Synthetic aperture radar is a relatively new remote sensing platform and the technology has matured a lot in the last two decades. This paper introduces the concepts behind SAR principles as well as the major areas where this new technology has shown additional information. (author)

  8. Fused upper central incisors: management of two clinical cases

    OpenAIRE

    Sfasciotti, Gian Luca; Marini, Roberta; Bossù, Maurizio; Ierardo, Gaetano; Annibali, Susanna

    2012-01-01

    This paper reports the management of two clinical cases, in which the upper right central incisor was fused with a supernumerary tooth and the upper left central incisor was macrodontic. A radiographic examination revealed that the fused teeth had two separate roots. Hemisectioning of the fused teeth was performed, the supernumerary portion was extracted and the remaining part was reshaped to remove any sharp margins and to achieve a normal morphology. The macrodontic central incisors were no...

  9. Analysis of lipoproteins by capillary zone electrophoresis in microfluidic devices: Assay development and surface roughness measurements

    NARCIS (Netherlands)

    Weiller, Bruce H.; Ceriotti, Laura; Shibata, Takayuki; Rein, Dietrich; Roberts, Matthew A.; Lichtenberg, Jan; German, J. Bruce; De Rooij, Nico F.; Verpoorte, Elisabeth

    2002-01-01

    The development of a new assay for lipoproteins by capillary electrophoresis in fused-silica capillaries and in glass microdevices is described in this paper. The separation of low-density (LDL) and high-density (HDL) lipoproteins by capillary zone electrophoresis is demonstrated in fused-silica

  10. Silica-Immobilized Enzyme Reactors

    Science.gov (United States)

    2007-08-01

    Silica-IMERs 14 implicated in neurological disorders such as Schizophrenia and Parkinson’s disease.[86] Drug discovery for targets that can alter the...primarily the activation of prodrugs and proantibiotics for cancer treatments or antibiotic therapy , respectively.[87] Nitrobenzene nitroreductase was...BuChE) Monolith disks* Packed Silica Biosilica Epoxide- Silica Silica-gel Enzyme Human AChE Human AChE Human AChE Equine BuChE Human

  11. MASS BALANCE OF SILICA IN STRAW FROM THE PERSPECTIVE OF SILICA REDUCTION IN STRAW PULP

    Directory of Open Access Journals (Sweden)

    Celil Atik,

    2012-06-01

    Full Text Available The high silica content of wheat straw is an important limiting factor for straw pulping. High silica content complicates processing and black liquor recovery, wears out factory installations, and lowers paper quality. Each section of wheat straw has different cells and chemical compositions and thus different silica content. In this work, the silica content of balled straw samples were examined according to their physical components, including internodes, nodes, leaves (sheath and blade, rachis, grain, other plant bodies, and other plant spikes. Mass distribution of silica was determined by a dry ashing method. Half (50.90% of the silica comes from leaves, and its mechanical separation will reduce the silica content in wheat straw pulp significantly. Destroying silica bodies by sonication will increase the strength properties of straw pulp.

  12. Liquid Phase Deposition of Silica on the Hexagonally Close-Packed Monolayer of Silica Spheres

    Directory of Open Access Journals (Sweden)

    Seo Young Yoon

    2013-01-01

    Full Text Available Liquid phase deposition is a method used for the nonelectrochemical production of polycrystalline ceramic films at low temperatures, most commonly silicon dioxide films. Herein, we report that silica spheres are organized in a hexagonal close-packed array using a patterned substrate. On this monolayer of silica spheres, we could fabricate new nanostructures in which deposition and etching compete through a modified LPD reaction. In the early stage, silica spheres began to undergo etching, and then, silica bridges between the silica spheres appeared by the local deposition reaction. Finally, the silica spheres and bridges disappeared completely. We propose the mechanism for the formation of nanostructure.

  13. Fast-neutron, coded-aperture imager

    International Nuclear Information System (INIS)

    Woolf, Richard S.; Phlips, Bernard F.; Hutcheson, Anthony L.; Wulf, Eric A.

    2015-01-01

    This work discusses a large-scale, coded-aperture imager for fast neutrons, building off a proof-of concept instrument developed at the U.S. Naval Research Laboratory (NRL). The Space Science Division at the NRL has a heritage of developing large-scale, mobile systems, using coded-aperture imaging, for long-range γ-ray detection and localization. The fast-neutron, coded-aperture imaging instrument, designed for a mobile unit (20 ft. ISO container), consists of a 32-element array of 15 cm×15 cm×15 cm liquid scintillation detectors (EJ-309) mounted behind a 12×12 pseudorandom coded aperture. The elements of the aperture are composed of 15 cm×15 cm×10 cm blocks of high-density polyethylene (HDPE). The arrangement of the aperture elements produces a shadow pattern on the detector array behind the mask. By measuring of the number of neutron counts per masked and unmasked detector, and with knowledge of the mask pattern, a source image can be deconvolved to obtain a 2-d location. The number of neutrons per detector was obtained by processing the fast signal from each PMT in flash digitizing electronics. Digital pulse shape discrimination (PSD) was performed to filter out the fast-neutron signal from the γ background. The prototype instrument was tested at an indoor facility at the NRL with a 1.8-μCi and 13-μCi 252Cf neutron/γ source at three standoff distances of 9, 15 and 26 m (maximum allowed in the facility) over a 15-min integration time. The imaging and detection capabilities of the instrument were tested by moving the source in half- and one-pixel increments across the image plane. We show a representative sample of the results obtained at one-pixel increments for a standoff distance of 9 m. The 1.8-μCi source was not detected at the 26-m standoff. In order to increase the sensitivity of the instrument, we reduced the fastneutron background by shielding the top, sides and back of the detector array with 10-cm-thick HDPE. This shielding configuration led

  14. Fast-neutron, coded-aperture imager

    Energy Technology Data Exchange (ETDEWEB)

    Woolf, Richard S., E-mail: richard.woolf@nrl.navy.mil; Phlips, Bernard F., E-mail: bernard.phlips@nrl.navy.mil; Hutcheson, Anthony L., E-mail: anthony.hutcheson@nrl.navy.mil; Wulf, Eric A., E-mail: eric.wulf@nrl.navy.mil

    2015-06-01

    This work discusses a large-scale, coded-aperture imager for fast neutrons, building off a proof-of concept instrument developed at the U.S. Naval Research Laboratory (NRL). The Space Science Division at the NRL has a heritage of developing large-scale, mobile systems, using coded-aperture imaging, for long-range γ-ray detection and localization. The fast-neutron, coded-aperture imaging instrument, designed for a mobile unit (20 ft. ISO container), consists of a 32-element array of 15 cm×15 cm×15 cm liquid scintillation detectors (EJ-309) mounted behind a 12×12 pseudorandom coded aperture. The elements of the aperture are composed of 15 cm×15 cm×10 cm blocks of high-density polyethylene (HDPE). The arrangement of the aperture elements produces a shadow pattern on the detector array behind the mask. By measuring of the number of neutron counts per masked and unmasked detector, and with knowledge of the mask pattern, a source image can be deconvolved to obtain a 2-d location. The number of neutrons per detector was obtained by processing the fast signal from each PMT in flash digitizing electronics. Digital pulse shape discrimination (PSD) was performed to filter out the fast-neutron signal from the γ background. The prototype instrument was tested at an indoor facility at the NRL with a 1.8-μCi and 13-μCi 252Cf neutron/γ source at three standoff distances of 9, 15 and 26 m (maximum allowed in the facility) over a 15-min integration time. The imaging and detection capabilities of the instrument were tested by moving the source in half- and one-pixel increments across the image plane. We show a representative sample of the results obtained at one-pixel increments for a standoff distance of 9 m. The 1.8-μCi source was not detected at the 26-m standoff. In order to increase the sensitivity of the instrument, we reduced the fastneutron background by shielding the top, sides and back of the detector array with 10-cm-thick HDPE. This shielding configuration led

  15. Fabrication of isolated platinum nanowire gratings and nanoparticles on silica substrate by femtosecond laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Nakajima, Yasutaka [School of Integrated Design Engineering, Keio University, 3-14-1, Hiyoshi, Kohoku-ku, Yokohama 223- 8522 (Japan); Nedyalkov, Nikolay [Institute of Electronics, Bulgarian Academy of Sciences, Tzarigradsko shouse 72, Sofia 1784 (Bulgaria); Department of Electronics and Electrical Engineering, Keio University, 3-14-1, Hiyoshi, Kohoku-ku, Yokohama, 223-8522 (Japan); Takami, Akihiro [School of Integrated Design Engineering, Keio University, 3-14-1, Hiyoshi, Kohoku-ku, Yokohama 223- 8522 (Japan); Terakawa, Mitsuhiro, E-mail: terakawa@elec.keio.ac.jp [School of Integrated Design Engineering, Keio University, 3-14-1, Hiyoshi, Kohoku-ku, Yokohama 223- 8522 (Japan); Department of Electronics and Electrical Engineering, Keio University, 3-14-1, Hiyoshi, Kohoku-ku, Yokohama, 223-8522 (Japan)

    2017-02-01

    Highlights: • Formation of HSFL with periodicities shorter than 100 nm. • Structural evolution from platinum nanowire gratings to platinum nanoparticles only by increasing the number of pulses. • Melting and fragmentation of the nanowire gratings would play a key role in structural evolution. - Abstract: 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.

  16. Multi-antenna synthetic aperture radar

    CERN Document Server

    Wang, Wen-Qin

    2013-01-01

    Synthetic aperture radar (SAR) is a well-known remote sensing technique, but conventional single-antenna SAR is inherently limited by the minimum antenna area constraint. Although there are still technical issues to overcome, multi-antenna SAR offers many benefits, from improved system gain to increased degrees-of-freedom and system flexibility. Multi-Antenna Synthetic Aperture Radar explores the potential and challenges of using multi-antenna SAR in microwave remote sensing applications. These applications include high-resolution imaging, wide-swath remote sensing, ground moving target indica

  17. Dynamic metamaterial aperture for microwave imaging

    International Nuclear Information System (INIS)

    Sleasman, Timothy; Imani, Mohammadreza F.; Gollub, Jonah N.; Smith, David R.

    2015-01-01

    We present a dynamic metamaterial aperture for use in computational imaging schemes at microwave frequencies. The aperture consists of an array of complementary, resonant metamaterial elements patterned into the upper conductor of a microstrip line. Each metamaterial element contains two diodes connected to an external control circuit such that the resonance of the metamaterial element can be damped by application of a bias voltage. Through applying different voltages to the control circuit, select subsets of the elements can be switched on to create unique radiation patterns that illuminate the scene. Spatial information of an imaging domain can thus be encoded onto this set of radiation patterns, or measurements, which can be processed to reconstruct the targets in the scene using compressive sensing algorithms. We discuss the design and operation of a metamaterial imaging system and demonstrate reconstructed images with a 10:1 compression ratio. Dynamic metamaterial apertures can potentially be of benefit in microwave or millimeter wave systems such as those used in security screening and through-wall imaging. In addition, feature-specific or adaptive imaging can be facilitated through the use of the dynamic aperture

  18. Dynamic metamaterial aperture for microwave imaging

    Energy Technology Data Exchange (ETDEWEB)

    Sleasman, Timothy; Imani, Mohammadreza F.; Gollub, Jonah N.; Smith, David R. [Center for Metamaterials and Integrated Plasmonics, Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina, 27708 (United States)

    2015-11-16

    We present a dynamic metamaterial aperture for use in computational imaging schemes at microwave frequencies. The aperture consists of an array of complementary, resonant metamaterial elements patterned into the upper conductor of a microstrip line. Each metamaterial element contains two diodes connected to an external control circuit such that the resonance of the metamaterial element can be damped by application of a bias voltage. Through applying different voltages to the control circuit, select subsets of the elements can be switched on to create unique radiation patterns that illuminate the scene. Spatial information of an imaging domain can thus be encoded onto this set of radiation patterns, or measurements, which can be processed to reconstruct the targets in the scene using compressive sensing algorithms. We discuss the design and operation of a metamaterial imaging system and demonstrate reconstructed images with a 10:1 compression ratio. Dynamic metamaterial apertures can potentially be of benefit in microwave or millimeter wave systems such as those used in security screening and through-wall imaging. In addition, feature-specific or adaptive imaging can be facilitated through the use of the dynamic aperture.

  19. Integrated electrochromic aperture diaphragm

    Science.gov (United States)

    Deutschmann, T.; Oesterschulze, E.

    2014-05-01

    In the last years, the triumphal march of handheld electronics with integrated cameras has opened amazing fields for small high performing optical systems. For this purpose miniaturized iris apertures are of practical importance because they are essential to control both the dynamic range of the imaging system and the depth of focus. Therefore, we invented a micro optical iris based on an electrochromic (EC) material. This material changes its absorption in response to an applied voltage. A coaxial arrangement of annular rings of the EC material is used to establish an iris aperture without need of any mechanical moving parts. The advantages of this device do not only arise from the space-saving design with a thickness of the device layer of 50μm. But it also benefits from low power consumption. In fact, its transmission state is stable in an open circuit, phrased memory effect. Only changes of the absorption require a voltage of up to 2 V. In contrast to mechanical iris apertures the absorption may be controlled on an analog scale offering the opportunity for apodization. These properties make our device the ideal candidate for battery powered and space-saving systems. We present optical measurements concerning control of the transmitted intensity and depth of focus, and studies dealing with switching times, light scattering, and stability. While the EC polymer used in this study still has limitations concerning color and contrast, the presented device features all functions of an iris aperture. In contrast to conventional devices it offers some special features. Owing to the variable chemistry of the EC material, its spectral response may be adjusted to certain applications like color filtering in different spectral regimes (UV, optical range, infrared). Furthermore, all segments may be switched individually to establish functions like spatial Fourier filtering or lateral tunable intensity filters.

  20. Fast-neutron, coded-aperture imager

    Science.gov (United States)

    Woolf, Richard S.; Phlips, Bernard F.; Hutcheson, Anthony L.; Wulf, Eric A.

    2015-06-01

    This work discusses a large-scale, coded-aperture imager for fast neutrons, building off a proof-of concept instrument developed at the U.S. Naval Research Laboratory (NRL). The Space Science Division at the NRL has a heritage of developing large-scale, mobile systems, using coded-aperture imaging, for long-range γ-ray detection and localization. The fast-neutron, coded-aperture imaging instrument, designed for a mobile unit (20 ft. ISO container), consists of a 32-element array of 15 cm×15 cm×15 cm liquid scintillation detectors (EJ-309) mounted behind a 12×12 pseudorandom coded aperture. The elements of the aperture are composed of 15 cm×15 cm×10 cm blocks of high-density polyethylene (HDPE). The arrangement of the aperture elements produces a shadow pattern on the detector array behind the mask. By measuring of the number of neutron counts per masked and unmasked detector, and with knowledge of the mask pattern, a source image can be deconvolved to obtain a 2-d location. The number of neutrons per detector was obtained by processing the fast signal from each PMT in flash digitizing electronics. Digital pulse shape discrimination (PSD) was performed to filter out the fast-neutron signal from the γ background. The prototype instrument was tested at an indoor facility at the NRL with a 1.8-μCi and 13-μCi 252Cf neutron/γ source at three standoff distances of 9, 15 and 26 m (maximum allowed in the facility) over a 15-min integration time. The imaging and detection capabilities of the instrument were tested by moving the source in half- and one-pixel increments across the image plane. We show a representative sample of the results obtained at one-pixel increments for a standoff distance of 9 m. The 1.8-μCi source was not detected at the 26-m standoff. In order to increase the sensitivity of the instrument, we reduced the fastneutron background by shielding the top, sides and back of the detector array with 10-cm-thick HDPE. This shielding configuration led

  1. Congenital pyriform aperture stenosis

    International Nuclear Information System (INIS)

    Osovsky, Micky; Aizer-Danon, Anat; Horev, Gadi; Sirota, Lea

    2007-01-01

    Nasal airway obstruction is a potentially life-threatening condition in the newborn. Neonates are obligatory nasal breathers. The pyriform aperture is the narrowest, most anterior bony portion of the nasal airway, and a decrease in its cross-sectional area will significantly increase nasal airway resistance. Congenital nasal pyriform aperture stenosis (CNPAS) is a rare, unusual form of nasal obstruction. It should be considered in the differential diagnosis of any neonate or infant with signs and symptoms of upper airway compromise. It is important to differentiate this level of obstruction from the more common posterior choanal stenosis or atresia. CNPAS presents with symptoms of nasal airway obstruction, which are often characterized by episodic apnea and cyclical cyanosis. (orig.)

  2. Extended Aperture Photometry of K2 RR Lyrae stars

    Science.gov (United States)

    Plachy, Emese; Klagyivik, Péter; Molnár, László; Sódor, Ádám; Szabó, Róbert

    2017-10-01

    We present the method of the Extended Aperture Photometry (EAP) that we applied on K2 RR Lyrae stars. Our aim is to minimize the instrumental variations of attitude control maneuvers by using apertures that cover the positional changes in the field of view thus contain the stars during the whole observation. We present example light curves that we compared to the light curves from the K2 Systematics Correction (K2SC) pipeline applied on the automated Single Aperture Photometry (SAP) and on the Pre-search Data Conditioning Simple Aperture Photometry (PDCSAP) data.

  3. Grafting of polymer onto silica surface in the presence of γ-ray irradiated silica

    International Nuclear Information System (INIS)

    Tsuchida, A.; Yokoyama, R.; Takami, M.; Chen, J.; Ohta, M.; Tsubokawa, N.

    2002-01-01

    Complete text of publication follows. We have reported the graft polymerization of vinyl monomers initiated by surface radicals formed by the decomposition of azo and peroxide groups previously introduced onto the surface. In addition, the grafting of polymers onto carbon black has been reported by the reaction of polymer radicals with the surface. On the other hand, it is well known that the relatively stable radicals are generated on the surface by the γ-ray irradiation. In this paper, the grafting of polystyrene onto silica surface during the thermal polymerization of styrene in the presence of γ-ray irradiated silica, grafting mechanism and thermal stability of grafted polymer will be discussed. The grafting of polymers onto silica surface by irradiation of polymer-adsorbed silica was also investigated. Silica obtained from Mitsubishi Chemical Co., Japan was used after pulverization: the particle size was 0.037-0.088 mm. Irradiation was performed in Cs-137 source at room temperature. The silica was irradiated at 50 Gy with dose rate of 3.463 Gy/min. Into a polymerization tube, styrene and irradiated silica was charged and the polymerization was carried out under argon under stirring. The percentage of polystyrene grafting was determined from weight loss when polystyrene-grafted silica was heated at 600 deg C by a thermal analyzer. Untreated silica did not affect the thermal polymerization of styrene. On the contrary, the thermal polymerization of styrene was remarkably retarded in the presence of the irradiated silica at 60 deg C. Similar tendency was reported during the polymerization of vinyl monomers in the presence of carbon black. In the initial stage of the polymerization in the presence of the irradiated silica below 50 deg C, the polymerization was accelerated. During the polymerization in the presence of irradiated silica, polystyrene was grafted onto the surface: the percentage of grafting was 5-11%. The amount of polystyrene grafted onto silica

  4. Aperture meter for the Large Hadron Collider

    International Nuclear Information System (INIS)

    Mueller, G.J.; Fuchsberger, K.; Redaelli, S.

    2012-01-01

    The control of the high intensity beams of the CERN Large Hadron Collider (LHC) is particular challenging and requires a good modeling of the machine and monitoring of various machine parameters. During operation it is crucial to ensure a minimal distance between the beam edge and the aperture of sensitive equipment, e.g. the superconducting magnets, which in all cases must be in the shadow of the collimator's that protect the machine. Possible dangerous situations must be detected as soon as possible. In order to provide the operator with information about the current machine bottlenecks an aperture meter application was developed based on the LHC online modeling tool-chain. The calculation of available free aperture takes into account the best available optics and aperture model as well as the relevant beam measurements. This paper describes the design and integration of this application into the control environment and presents results of the usage in daily operation and from validation measurements. (authors)

  5. Hydrothermal stability of microporous silica and niobia-silica membranes

    NARCIS (Netherlands)

    Boffa, V.; Blank, David H.A.; ten Elshof, Johan E.

    2008-01-01

    The hydrothermal stability of microporous niobia–silica membranes was investigated and compared with silica membranes. The membranes were exposed to hydrothermal conditions at 150 and 200 °C for 70 h. The change of pore structure before and after exposure to steam was probed by single-gas permeation

  6. High-contrast imaging with an arbitrary aperture: Active compensation of aperture discontinuities

    International Nuclear Information System (INIS)

    Pueyo, Laurent; Norman, Colin

    2013-01-01

    We present a new method to achieve high-contrast images using segmented and/or on-axis telescopes. Our approach relies on using two sequential deformable mirrors (DMs) to compensate for the large amplitude excursions in the telescope aperture due to secondary support structures and/or segment gaps. In this configuration the parameter landscape of DM surfaces that yield high-contrast point-spread functions is not linear, and nonlinear methods are needed to find the true minimum in the optimization topology. We solve the highly nonlinear Monge-Ampere equation that is the fundamental equation describing the physics of phase-induced amplitude modulation. We determine the optimum configuration for our two sequential DM system and show that high-throughput and high-contrast solutions can be achieved using realistic surface deformations that are accessible using existing technologies. We name this process Active Compensation of Aperture Discontinuities (ACAD). We show that for geometries similar to the James Webb Space Telescope, ACAD can attain at least 10 –7 in contrast and an order of magnitude higher for both the future extremely large telescopes and on-axis architectures reminiscent of the Hubble Space Telescope. We show that the converging nonlinear mappings resulting from our DM shapes actually damp near-field diffraction artifacts in the vicinity of the discontinuities. Thus, ACAD actually lowers the chromatic ringing due to diffraction by segment gaps and struts while not amplifying the diffraction at the aperture edges beyond the Fresnel regime. This outer Fresnel ringing can be mitigated by properly designing the optical system. Consequently, ACAD is a true broadband solution to the problem of high-contrast imaging with segmented and/or on-axis apertures. We finally show that once the nonlinear solution is found, fine tuning with linear methods used in wavefront control can be applied to further contrast by another order of magnitude. Generally speaking, the

  7. Computational model of exploding metallic fuses for multimegajoule switching

    International Nuclear Information System (INIS)

    Lindemuth, I.R.; Brownell, J.H.; Greene, A.E.; Nickel, G.H.; Oliphant, T.A.; Weiss, D.L.

    1985-01-01

    A new model for determining the time-dependent behavior of exploding metallic fuses is formulated. The model draws on an atomic data base and gives insight into the temporal behavior of the material density and temperature of the fuse as well as the nonlinear electrical circuit interaction. The model includes an embedding insulating tamper and leads to a plausible explanation of fuse ''restrike.'' The model predicts time-scale compression of 500 for inductive store systems powered by explosive driven magnetic flux compression generators. A scenario for achieving multimegajoule foil implosions is predicted

  8. Serpentinization processes: Influence of silica

    Science.gov (United States)

    Huang, R.; Sun, W.; Ding, X.; Song, M.; Zhan, W.

    2016-12-01

    Serpentinization systems are highly enriched in molecular hydrogen (H2) and hydrocarbons (e.g. methane, ethane and propane). The production of hydrocarbons results from reactions between H2 and oxidized carbon (carbon dioxide and carbon monoxide), which possibly contribute to climate changes during early history of the Earth. However, the influence of silica on the production of H2 and hydrocarbons was poorly constrained. We performed experiments at 311-500 °C and 3.0 kbar using mechanical mixtures of silica and olivine in ratios ranging from 0 to 40%. Molecular hydrogen (H2), methane, ethane and propane were formed, which were analyzed by gas chromatography. It was found that silica largely decreased H2 production. Without any silica, olivine serpentinization produced 94.5 mmol/kg H2 after 20 days of reaction time. By contrast, with the presence of 20% silica, H2 concentrations decreased largely, 8.5 mmol/kg. However, the influence of silica on the production of hydrocarbons is negligible. Moreover, with the addition of 20%-40% silica, the major hydrous minerals are talc, which was quantified according to an established standard curve calibrated by infrared spectroscopy analyses. It shows that silica greatly enhances olivine hydration, especially at 500 °C. Without any addition of silica, reaction extents were serpentinization at 500 °C and 3.0 kbar. By contrast, with the presence of 50% silica, olivine was completely transformed to talc within 9 days. This study indicates that silica impedes the oxidation of ferrous iron into ferric iron, and that rates of olivine hydration in natural geological settings are much faster with silica supply.

  9. Bilateral maxillary fused second and third molars: a rare occurrence.

    Science.gov (United States)

    Liang, Rui-Zhen; Wu, Jin-Tao; Wu, You-Nong; Smales, Roger J; Hu, Ming; Yu, Jin-Hua; Zhang, Guang-Dong

    2012-12-01

    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.

  10. Interfacial interaction between the epoxidized natural rubber and silica in natural rubber/silica composites

    Science.gov (United States)

    Xu, Tiwen; Jia, Zhixin; Luo, Yuanfang; Jia, Demin; Peng, Zheng

    2015-02-01

    The epoxidized natural rubber (ENR) as an interfacial modifier was used to improve the mechanical and dynamical mechanical properties of NR/silica composites. In order to reveal the interaction mechanism between ENR and silica, the ENR/Silica model compound was prepared by using an open mill and the interfacial interaction of ENR with silica was investigated by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), X-ray diffraction (XRD) and stress-strain testing. The results indicated that the ring-opening reaction occurs between the epoxy groups of ENR chains and Si-OH groups on the silica surfaces and the covalent bonds are formed between two phases, which can improve the dispersion of silica in the rubber matrix and enhance the interfacial combination between rubber and silica. The ring-opening reaction occurs not only in vulcanization process but also in mixing process, meanwhile, the latter seems to be more important due to the simultaneous effects of mechanical force and temperature.

  11. Fiber fuse behavior in kW-level continuous-wave double-clad field laser

    International Nuclear Information System (INIS)

    Sun Jun-Yi; Xiao Qi-Rong; Li Dan; Wang Xue-Jiao; Zhang Hai-Tao; Gong Ma-Li; Yan Ping

    2016-01-01

    In this study, original experimental data for fiber fuse in kW-level continuous-wave (CW) high power double-clad fiber (DCF) laser are reported. The propagating velocity of the fuse is 9.68 m/s in a 3.1-kW Yb-doped DCF laser. Three other cases in Yb-doped DCF are also observed. We think that the ignition of fiber fuse is caused by thermal mechanism, and the formation of bullet-shaped tracks is attributed to the optical discharge and temperature gradient. The inducements of initial fuse and formation of bullet-shaped voids are analyzed. This investigation of fiber fuse helps better understand the fiber fuse behavior, in order to avoid the catastrophic destruction caused by fiber fuse in high power fiber laser. (paper)

  12. Extended Aperture Photometry of K2 RR Lyrae stars

    Directory of Open Access Journals (Sweden)

    Plachy Emese

    2017-01-01

    Full Text Available We present the method of the Extended Aperture Photometry (EAP that we applied on K2 RR Lyrae stars. Our aim is to minimize the instrumental variations of attitude control maneuvers by using apertures that cover the positional changes in the field of view thus contain the stars during the whole observation. We present example light curves that we compared to the light curves from the K2 Systematics Correction (K2SC pipeline applied on the automated Single Aperture Photometry (SAP and on the Pre-search Data Conditioning Simple Aperture Photometry (PDCSAP data.

  13. Influence of coma aberration on aperture averaged scintillations in oceanic turbulence

    Science.gov (United States)

    Luo, Yujuan; Ji, Xiaoling; Yu, Hong

    2018-01-01

    The influence of coma aberration on aperture averaged scintillations in oceanic turbulence is studied in detail by using the numerical simulation method. In general, in weak oceanic turbulence, the aperture averaged scintillation can be effectively suppressed by means of the coma aberration, and the aperture averaged scintillation decreases as the coma aberration coefficient increases. However, in moderate and strong oceanic turbulence the influence of coma aberration on aperture averaged scintillations can be ignored. In addition, the aperture averaged scintillation dominated by salinity-induced turbulence is larger than that dominated by temperature-induced turbulence. In particular, it is shown that for coma-aberrated Gaussian beams, the behavior of aperture averaged scintillation index is quite different from the behavior of point scintillation index, and the aperture averaged scintillation index is more suitable for characterizing scintillations in practice.

  14. Interfacial interaction between the epoxidized natural rubber and silica in natural rubber/silica composites

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Tiwen [College of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Jia, Zhixin, E-mail: zxjia@scut.edu.cn [College of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Luo, Yuanfang; Jia, Demin [College of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Peng, Zheng [Agricultural Product Processing Research Institute, Chinese Academy of Tropical Agriculture Sciences, Zhanjiang 524001 (China)

    2015-02-15

    Highlights: • Substantiate the ring open reaction between Si-OH of silica and epoxy groups of ENR. • ENR can act as a bridge between NR and silica to enhance the interfacial interaction. • As a modifier, ENR gets the potential to be used in the tread of green tire for improving the wet skid resistance apparently. - Abstract: The epoxidized natural rubber (ENR) as an interfacial modifier was used to improve the mechanical and dynamical mechanical properties of NR/silica composites. In order to reveal the interaction mechanism between ENR and silica, the ENR/Silica model compound was prepared by using an open mill and the interfacial interaction of ENR with silica was investigated by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), X-ray diffraction (XRD) and stress–strain testing. The results indicated that the ring-opening reaction occurs between the epoxy groups of ENR chains and Si-OH groups on the silica surfaces and the covalent bonds are formed between two phases, which can improve the dispersion of silica in the rubber matrix and enhance the interfacial combination between rubber and silica. The ring-opening reaction occurs not only in vulcanization process but also in mixing process, meanwhile, the latter seems to be more important due to the simultaneous effects of mechanical force and temperature.

  15. Large-aperture hybrid photo-detector

    International Nuclear Information System (INIS)

    Kawai, Y.; Nakayama, H.; Kusaka, A.; Kakuno, H.; Abe, T.; Iwasaki, M.; Aihara, H.; Tanaka, M.; Shiozawa, M.; Kyushima, H.; Suyama, M.

    2007-01-01

    We have developed the first complete large-aperture (13-inch diameter) hybrid photo-detector (HPD). The withstanding voltage problem has been overcome and we were able to attain an HPD operating voltage of +20 kV. Adoption of our newly developed backside illumination avalanche diode (AD) was also critical in successfully countering the additional problem of an increase in AD leakage after the activation process. We observed single photon signal timing jitter of under 450 ps in FWHM, electron transit time of ∼12 ns, and clear pulse height separation up to several photoelectron peaks, all greatly superior to the performance of any conventional large-aperture photomultiplier tubes (PMTs). In addition, our HPD has a much simpler structure than conventional large-aperture PMTs, which simplifies mass production and lowers manufacturing cost. We believe that these attributes position our HPD as the most suitable photo-detector for the next generation mega-ton class water-Cherenkov detector, which is expected to be more than 20x larger than the Super-Kamiokande (SK) detector

  16. Fuse and application of said fuse to the construction of an emergency shutdown system for a nuclear reactor

    International Nuclear Information System (INIS)

    Taulier, H.H.L.; Brugeille, G.

    1978-01-01

    A fuse device for an automatic emergency shutdown system in fast reactors provides a coupling between a casing tube placed within a fuel can and a series of neutron-absorbing masses held together above the reactor core under normal operating conditions but released in free fall to the lower portion of the casing tube at the level of the reactor core as a result of melting of the fuse when operating characteristics such as temperature or neutron flux attain a level which exceeds a predetermined threshold

  17. Fuse and application of said fuse to the construction of an emergency shutdown system for a nuclear reactor

    International Nuclear Information System (INIS)

    Taulier, H.H.L.; Brugeilles, G.

    1976-01-01

    A fuse device for an automatic emergency shutdown system in fast reactors provides a coupling between a casing tube placed within a fuel can and a series of neutron-absorbing masses held together above the reactor core under normal operating conditions. They are released in free fall to the lower portion of the casing tube at the level of the reactor core as a result of melting of the fuse when operating characteristics such as temperature or neutron flux attain a level which exceeds a predetermined threshold

  18. and 8-Membered Oxygen-containing Benzo-fused Rings using ...

    African Journals Online (AJOL)

    NJD

    A number of benzo-fused oxygen-containing heterocycles were synthesized from allyl-3-isopropoxy-4-methoxybenzaldehyde using metathesis or an alkene isomerization-metathesis sequence as key synthetic steps. Benzo-fused compounds thus formed included a 3,6-dihydro-1H-2-benzoxocine, ...

  19. Direct aperture optimization: A turnkey solution for step-and-shoot IMRT

    International Nuclear Information System (INIS)

    Shepard, D.M.; Earl, M.A.; Li, X.A.; Naqvi, S.; Yu, C.

    2002-01-01

    IMRT treatment plans for step-and-shoot delivery have traditionally been produced through the optimization of intensity distributions (or maps) for each beam angle. The optimization step is followed by the application of a leaf-sequencing algorithm that translates each intensity map into a set of deliverable aperture shapes. In this article, we introduce an automated planning system in which we bypass the traditional intensity optimization, and instead directly optimize the shapes and the weights of the apertures. We call this approach 'direct aperture optimization'. This technique allows the user to specify the maximum number of apertures per beam direction, and hence provides significant control over the complexity of the treatment delivery. This is possible because the machine dependent delivery constraints imposed by the MLC are enforced within the aperture optimization algorithm rather than in a separate leaf-sequencing step. The leaf settings and the aperture intensities are optimized simultaneously using a simulated annealing algorithm. We have tested direct aperture optimization on a variety of patient cases using the EGS4/BEAM Monte Carlo package for our dose calculation engine. The results demonstrate that direct aperture optimization can produce highly conformal step-and-shoot treatment plans using only three to five apertures per beam direction. As compared with traditional optimization strategies, our studies demonstrate that direct aperture optimization can result in a significant reduction in both the number of beam segments and the number of monitor units. Direct aperture optimization therefore produces highly efficient treatment deliveries that maintain the full dosimetric benefits of IMRT

  20. Analysis of optical properties behaviour of CLEARCERAM, fused silica and CaF2 glasses exposed to simulated space conditions

    Science.gov (United States)

    Fernández-Rodríguez, M.; Alvarado, C. G.; Núñez, A.; Álvarez-Herrero, A.

    2017-11-01

    produced by the radiation environment on the optical materials can be classified in two types: ionizing or non-ionizing. This damage may produce continual or accumulative (dose) alterations on the optical material performances, or may produce alterations which not remain along the time (transitory effects). The effects of the radiation on optical materials can be summarized on changes of optical transmission and refractive index, variation of density and superficial degradation [4-6]. Two non-invasive and non-destructive techniques such as Optical Spectrum Analyzer and Spectroscopic Ellipsometry [7] have been used to characterize optically the three kinds of studied glasses, CaF2, Fused Silica and Clearceram. The study of the temperature and radiation effects on the glasses optical properties showed that the gamma radiation is the principal responsible of glasses optical degradation. The optical properties of the Clearceram glass have been affected by the gamma irradiation due to the absorption bands induced by the radiation in the visible spectral range (color centers). Therefore, an analysis about the behavior of these color centers with the gamma radiation total dose and with the time after the irradiation has been carried out in the same way that it is performed in [8].

  1. Outbursts In Symbiotic Binaries (FUSE 2000)

    Science.gov (United States)

    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

  2. Multi-aperture digital coherent combining for free-space optical communication receivers.

    Science.gov (United States)

    Geisler, David J; Yarnall, Timothy M; Stevens, Mark L; Schieler, Curt M; Robinson, Bryan S; Hamilton, Scott A

    2016-06-13

    Space-to-ground optical communication systems can benefit from reducing the size, weight, and power profiles of space terminals. One way of reducing the required power-aperture product on a space platform is to implement effective, but costly, single-aperture ground terminals with large collection areas. In contrast, we present a ground terminal receiver architecture in which many small less-expensive apertures are efficiently combined to create a large effective aperture while maintaining excellent receiver sensitivity. This is accomplished via coherent detection behind each aperture followed by digitization. The digitized signals are then combined in a digital signal processing chain. Experimental results demonstrate lossless coherent combining of four lasercom signals, at power levels below 0.1 photons/bit/aperture.

  3. ELIMINATING NEGETIVE EFFECT OF INVERTER-BASED DGs ON FUSE-RECLOSER COORDINATION IN DISTRIBUTION SYSTEMS

    OpenAIRE

    shakarami, mahmoudreza; namdari, farhad; salehi, moslem

    2015-01-01

    Despite many advantages of distributed generation (DG) sources, they may have a negative effect on the protection of distribution systems. In a distribution system, fuse-recloser protection scheme is designed such that the recloser could operate faster than the fuse to prevent fuse burning; but, the presence of DGs in fault conditions may lead to increased fuse current and thus faster performance of the fuse than the recloser and lack of coordination. In this paper, effect of DGs on fuse-recl...

  4. Gas Separation through Bilayer Silica, the Thinnest Possible Silica Membrane.

    Science.gov (United States)

    Yao, Bowen; Mandrà, Salvatore; Curry, John O; Shaikhutdinov, Shamil; Freund, Hans-Joachim; Schrier, Joshua

    2017-12-13

    Membrane-based gas separation processes can address key challenges in energy and environment, but for many applications the permeance and selectivity of bulk membranes is insufficient for economical use. Theory and experiment indicate that permeance and selectivity can be increased by using two-dimensional materials with subnanometer pores as membranes. Motivated by experiments showing selective permeation of H 2 /CO mixtures through amorphous silica bilayers, here we perform a theoretical study of gas separation through silica bilayers. Using density functional theory calculations, we obtain geometries of crystalline free-standing silica bilayers (comprised of six-membered rings), as well as the seven-, eight-, and nine-membered rings that are observed in glassy silica bilayers, which arise due to Stone-Wales defects and vacancies. We then compute the potential energy barriers for gas passage through these various pore types for He, Ne, Ar, Kr, H 2 , N 2 , CO, and CO 2 gases, and use the data to assess their capability for selective gas separation. Our calculations indicate that crystalline bilayer silica, which is less than a nanometer thick, can be a high-selectivity and high-permeance membrane material for 3 He/ 4 He, He/natural gas, and H 2 /CO separations.

  5. Quantitative model of transport-aperture coordination during reach-to-grasp movements.

    Science.gov (United States)

    Rand, Miya K; Shimansky, Y P; Hossain, Abul B M I; Stelmach, George E

    2008-06-01

    It has been found in our previous studies that the initiation of aperture closure during reach-to-grasp movements occurs when the hand distance to target crosses a threshold that is a function of peak aperture amplitude, hand velocity, and hand acceleration. Thus, a stable relationship between those four movement parameters is observed at the moment of aperture closure initiation. Based on the concept of optimal control of movements (Naslin 1969) and its application for reach-to-grasp movement regulation (Hoff and Arbib 1993), it was hypothesized that the mathematical equation expressing that relationship can be generalized to describe coordination between hand transport and finger aperture during the entire reach-to-grasp movement by adding aperture velocity and acceleration to the above four movement parameters. The present study examines whether this hypothesis is supported by the data obtained in experiments in which young adults performed reach-to-grasp movements in eight combinations of two reach-amplitude conditions and four movement-speed conditions. It was found that linear approximation of the mathematical model described the relationship among the six movement parameters for the entire aperture-closure phase with very high precision for each condition, thus supporting the hypothesis for that phase. Testing whether one mathematical model could approximate the data across all the experimental conditions revealed that it was possible to achieve the same high level of data-fitting precision only by including in the model two additional, condition-encoding parameters and using a nonlinear, artificial neural network-based approximator with two hidden layers comprising three and two neurons, respectively. This result indicates that transport-aperture coordination, as a specific relationship between the parameters of hand transport and finger aperture, significantly depends on the condition-encoding variables. The data from the aperture-opening phase also fit a

  6. Fusing Facial Features for Face Recognition

    Directory of Open Access Journals (Sweden)

    Jamal Ahmad Dargham

    2012-06-01

    Full Text Available Face recognition is an important biometric method because of its potential applications in many fields, such as access control, surveillance, and human-computer interaction. In this paper, a face recognition system that fuses the outputs of three face recognition systems based on Gabor jets is presented. The first system uses the magnitude, the second uses the phase, and the third uses the phase-weighted magnitude of the jets. The jets are generated from facial landmarks selected using three selection methods. It was found out that fusing the facial features gives better recognition rate than either facial feature used individually regardless of the landmark selection method.

  7. Diffraction contrast imaging using virtual apertures

    International Nuclear Information System (INIS)

    Gammer, Christoph; Burak Ozdol, V.; Liebscher, Christian H.; Minor, Andrew M.

    2015-01-01

    Two methods on how to obtain the full diffraction information from a sample region and the associated reconstruction of images or diffraction patterns using virtual apertures are demonstrated. In a STEM-based approach, diffraction patterns are recorded for each beam position using a small probe convergence angle. Similarly, a tilt series of TEM dark-field images is acquired. The resulting datasets allow the reconstruction of either electron diffraction patterns, or bright-, dark- or annular dark-field images using virtual apertures. The experimental procedures of both methods are presented in the paper and are applied to a precipitation strengthened and creep deformed ferritic alloy with a complex microstructure. The reconstructed virtual images are compared with conventional TEM images. The major advantage is that arbitrarily shaped virtual apertures generated with image processing software can be designed without facing any physical limitations. In addition, any virtual detector that is specifically designed according to the underlying crystal structure can be created to optimize image contrast. - Highlights: • A dataset containing all structural information of a given position is recorded. • The dataset allows reconstruction of virtual diffraction patterns or images. • Specific virtual apertures are designed to image precipitates in a complex alloy. • Virtual diffraction patterns from arbitrarily small regions can be established. • Using STEM diffraction to record the dataset is more efficient than TEM dark-field

  8. Synthesis of uniform carbon at silica nanocables and luminescent silica nanotubes with well controlled inner diameters

    International Nuclear Information System (INIS)

    Qian Haisheng; Yu Shuhong; Ren Lei; Yang Yipeng; Zhang Wei

    2006-01-01

    Uniform carbon at silica nanocables and silica nanotubes with well-controlled inner diameters can be synthesized in an easy way by a sacrificial templating method. This was performed using carbon nanofibres as hard templates that were synthesized previously by a hydrothermal carbonization process. Silica nanotubes with well-controlled inner diameters were synthesized from carbon at silica core-shell nanostructures by removal of the core carbon component. The inner diameters of the as-prepared silica nanotubes can be well controlled from several nanometres to hundreds of nanometres by adjusting the diameters of the carbon nanofibres. The silica nanotubes synthesized by this method display strong photoluminescence in ultraviolet at room temperature. Such uniform silica nanotubes might find potential applications in many fields such as encapsulation, catalysis, chemical/biological separation, and sensing

  9. Coded aperture solution for improving the performance of traffic enforcement cameras

    Science.gov (United States)

    Masoudifar, Mina; Pourreza, Hamid Reza

    2016-10-01

    A coded aperture camera is proposed for automatic license plate recognition (ALPR) systems. It captures images using a noncircular aperture. The aperture pattern is designed for the rapid acquisition of high-resolution images while preserving high spatial frequencies of defocused regions. It is obtained by minimizing an objective function, which computes the expected value of perceptual deblurring error. The imaging conditions and camera sensor specifications are also considered in the proposed function. The designed aperture improves the depth of field (DoF) and subsequently ALPR performance. The captured images can be directly analyzed by the ALPR software up to a specific depth, which is 13 m in our case, though it is 11 m for the circular aperture. Moreover, since the deblurring results of images captured by our aperture yield fewer artifacts than those captured by the circular aperture, images can be first deblurred and then analyzed by the ALPR software. In this way, the DoF and recognition rate can be improved at the same time. Our case study shows that the proposed camera can improve the DoF up to 17 m while it is limited to 11 m in the conventional aperture.

  10. Silica/Perfluoropolymer nanocomposites fabricated by direct melt-compounding: a novel method without surface modification on nano-silica.

    Science.gov (United States)

    Tanahashi, Mitsuru; Hirose, Masaki; Watanabe, Yusuke; Lee, Jeong-Chang; Takeda, Kunihiko

    2007-07-01

    A novel method for the fabrication of silica/perfluoropolymer nanocomposites was investigated, whereby nano-sized silica particles without surface modification were dispersed uniformly through mechanical breakdown of loosely packed agglomerates of silica nanoparticles with low fracture strength in a polymer melt during direct melt-compounding. The method consists of two stages. The first stage involves preparation of the loose silica agglomerate, and the second stage involves melt-compounding of a completely hydrophobic perfluoropolymer, poly(tetrafluoroethyleneco-perfluoropropylvinylether), with the loose silica agglomerates prepared in the first stage. In the first stage, the packing structure and the fracture strength of the silica agglomerate were controlled by destabilizing an aqueous colloidal silica solution with a mean primary diameter of 190 nm via pH control and salt addition. In the next stage, the silica/perfluoropolymer nanocomposite was fabricated by breaking down the prepared loose silica agglomerates with low fracture strength by means of a shear force inside the polymer melt during melt-compounding.

  11. Hole-assisted fiber based fiber fuse terminator supporting 22 W input

    Science.gov (United States)

    Tsujikawa, Kyozo; Kurokawa, Kenji; Hanzawa, Nobutomo; Nozoe, Saki; Matsui, Takashi; Nakajima, Kazuhide

    2018-05-01

    We investigated the air hole structure in hole-assisted fiber (HAF) with the aim of terminating fiber fuse propagation. We focused on two structural parameters c/MFD and S1/S2, which are related respectively to the position and area of the air holes, and mapped their appropriate values for terminating fiber fuse propagation. Here, MFD is the mode field diameter, c is the diameter of an inscribed circle linking the air holes, S1 is the total area of the air holes, and S2 is the area of a circumscribed circle linking the air holes. On the basis of these results, we successfully realized a compact fiber fuse terminator consisting of a 1.35 mm-long HAF, which can terminate fiber fuse propagation even with a 22 W input. In addition, we observed fiber fuse termination using a high-speed camera. We additionally confirmed that the HAF-based fiber fuse terminator is effective under various input power conditions. The penetration length of the optical discharge in the HAF was only less than 300 μm when the input power was from 2 to 22 W.

  12. Fused upper central incisors: management of two clinical cases.

    Science.gov (United States)

    Sfasciotti, Gian Luca; Marini, Roberta; Bossù, Maurizio; Ierardo, Gaetano; Annibali, Susanna

    2011-03-01

    This paper reports the management of two clinical cases, in which the upper right central incisor was fused with a supernumerary tooth and the upper left central incisor was macrodontic. A radiographic examination revealed that the fused teeth had two separate roots. Hemisectioning of the fused teeth was performed, the supernumerary portion was extracted and the remaining part was reshaped to remove any sharp margins and to achieve a normal morphology. The macrodontic central incisors were not treated. At 12-months post-surgery there were no periodontal problems and no hypersensitivity. Orthodontic treatment was performed to appropriately align the maxillary teeth and to correct the malocclusion.

  13. [Effects of laser welding on bond of porcelain fused cast pure titanium].

    Science.gov (United States)

    Zhu, Juan-fang; He, Hui-ming; Gao, Bo; Wang, Zhong-yi

    2006-04-01

    To investigate the influence of the laser welding on bond of porcelain fused to cast pure titanium. Twenty cast titanium plates were divided into two groups: laser welded group and control group. The low-fusing porcelain was fused to the laser welded cast pure titanium plates at fusion zone. The bond strength of the porcelain to laser welded cast pure titanium was measured by the three-point bending test. The interface of titanium and porcelain was investigated by scanning electron microscopy (SEM) and energy depressive X-ray detector (EDX). The non-welded titanium plates were used as comparison. No significant difference of the bond strength was found between laser-welded samples [(46.85 +/- 0.76) MPa] and the controls [(41.71 +/- 0.55) MPa] (P > 0.05). The SEM displayed the interface presented similar irregularities with a predominance. The titanium diffused to low-fusing porcelain, while silicon and aluminum diffused to titanium basement. Laser welding does not affect low-fusing porcelain fused to pure titanium.

  14. Use of Silica-Encapsulated Pseudomonas sp. Strain NCIB 9816-4 in Biodegradation of Novel Hydrocarbon Ring Structures Found in Hydraulic Fracturing Waters

    Science.gov (United States)

    Aukema, Kelly G.; Kasinkas, Lisa; Aksan, Alptekin

    2014-01-01

    The most problematic hydrocarbons in hydraulic fracturing (fracking) wastewaters consist of fused, isolated, bridged, and spiro ring systems, and ring systems have been poorly studied with respect to biodegradation, prompting the testing here of six major ring structural subclasses using a well-characterized bacterium and a silica encapsulation system previously shown to enhance biodegradation. The direct biological oxygenation of spiro ring compounds was demonstrated here. These and other hydrocarbon ring compounds have previously been shown to be present in flow-back waters and waters produced from hydraulic fracturing operations. Pseudomonas sp. strain NCIB 9816-4, containing naphthalene dioxygenase, was selected for its broad substrate specificity, and it was demonstrated here to oxidize fundamental ring structures that are common in shale-derived waters but not previously investigated with this or related enzymes. Pseudomonas sp. NCIB 9816-4 was tested here in the presence of a silica encasement, a protocol that has previously been shown to protect bacteria against the extremes of salinity present in fracking wastewaters. These studies demonstrate the degradation of highly hydrophobic compounds by a silica-encapsulated model bacterium, demonstrate what it may not degrade, and contribute to knowledge of the full range of hydrocarbon ring compounds that can be oxidized using Pseudomonas sp. NCIB 9816-4. PMID:24907321

  15. Renal cell carcinoma in patient with crossed fused renal ectopia

    Directory of Open Access Journals (Sweden)

    Ozgur Cakmak

    2016-01-01

    Full Text Available Primary renal cell carcinomas have rarely been reported in patients with crossed fused renal ectopia. We presented a patient with right to left crossed fused kidney harbouring renal tumor. The most frequent tumor encountered in crossed fused renal ectopia is renal cell carcinoma. In this case, partial nephrectomy was performed which pave way to preservation of the uninvolved both renal units. Due to unpredictable anatomy, careful preoperative planning and meticulous delineation of renal vasculature is essential for preservation of the uninvolved renal units.

  16. Pattern Synthesis of Dual-band Shared Aperture Interleaved Linear Antenna Arrays

    Directory of Open Access Journals (Sweden)

    H. Guo

    2014-09-01

    Full Text Available This paper presents an approach to improve the efficiency of an array aperture by interleaving two different arrays in the same aperture area. Two sub-arrays working at different frequencies are interleaved in the same linear aperture area. The available aperture area is efficiently used. The element positions of antenna array are optimized by using Invasive Weed Optimization (IWO to reduce the peak side lobe level (PSLL of the radiation pattern. To overcome the shortness of traditional methods which can only fulfill the design of shared aperture antenna array working at the same frequency, this method can achieve the design of dual-band antenna array with wide working frequency range. Simulation results show that the proposed method is feasible and efficient in the synthesis of dual-band shared aperture antenna array.

  17. Solar energy apparatus with apertured shield

    Science.gov (United States)

    Collings, Roger J. (Inventor); Bannon, David G. (Inventor)

    1989-01-01

    A protective apertured shield for use about an inlet to a solar apparatus which includesd a cavity receiver for absorbing concentrated solar energy. A rigid support truss assembly is fixed to the periphery of the inlet and projects radially inwardly therefrom to define a generally central aperture area through which solar radiation can pass into the cavity receiver. A non-structural, laminated blanket is spread over the rigid support truss in such a manner as to define an outer surface area and an inner surface area diverging radially outwardly from the central aperture area toward the periphery of the inlet. The outer surface area faces away from the inlet and the inner surface area faces toward the cavity receiver. The laminated blanket includes at least one layer of material, such as ceramic fiber fabric, having high infra-red emittance and low solar absorption properties, and another layer, such as metallic foil, of low infra-red emittance properties.

  18. Class of near-perfect coded apertures

    International Nuclear Information System (INIS)

    Cannon, T.M.; Fenimore, E.E.

    1978-01-01

    The encoding/decoding method produces artifacts, which even in the absence of quantum noise, restrict the quality of the reconstructed image. This is true of most correlation-type methods. If the decoding procedure is of the deconvolution variety, small terms in the transfer function of the aperture can lead to excessive noise in the reconstructed image. The authors propose to circumvent both of these problems by use of a uniformly redundant array (URA) as the coded aperture in conjunction with a special correlation decoding method. The correlation of the decoding array with the aperture results in a delta function with deterministically zero sidelobes. It is shown that the reconstructed image in the URA system contains virtually uniform noise regardless of the structure in the original source. Therefore, the improvement over a single pinhole camera will be relatively larger for the brighter points in the source than for the low intensity points. 12 refs

  19. Sonochemical coating of magnetite nanoparticles with silica.

    Science.gov (United States)

    Dang, Feng; Enomoto, Naoya; Hojo, Junichi; Enpuku, Keiji

    2010-01-01

    Magnetite nanoparticles were coated with silica through the hydrolysis and condensation of tetraethyl orthosilicate (TEOS) under ultrasonic irradiation. The ultrasonic irradiation was used to prevent the agglomeration of the magnetite particles and accelerate the hydrolysis and condensation of TEOS. TEM, DLS, XRF, VSM, TG and sedimentation test were used to characterize the silica-coated magnetite particles. The dispersibility of silica-coated magnetite particles in aqueous solution was improved significantly and the agglomerate particle size was decreased to 110 nm. It was found that the agglomerate particle size of silica-coated magnetite particles was mainly decided by the coating temperature and the pH value in the silica-coating process. The weight ratio of silica in silica-coated magnetite particles was mainly decided by the pH value in the silica-coating process. The dispersibility of silica-coated magnetite particles was mainly decided by the agglomerate particle size of the suspension. The oxidation of magnetite particles in air was limited through the coated silica. The magnetism of silica-coated magnetite particles decreased slightly after silica-coating.

  20. Synthetic aperture design for increased SAR image rate

    Science.gov (United States)

    Bielek, Timothy P [Albuquerque, NM; Thompson, Douglas G [Albuqerque, NM; Walker, Bruce C [Albuquerque, NM

    2009-03-03

    High resolution SAR images of a target scene at near video rates can be produced by using overlapped, but nevertheless, full-size synthetic apertures. The SAR images, which respectively correspond to the apertures, can be analyzed in sequence to permit detection of movement in the target scene.

  1. Silica reinforced triblock copolymer gels

    DEFF Research Database (Denmark)

    Theunissen, E.; Overbergh, N.; Reynaers, H.

    2004-01-01

    The effect of silica and polymer coated silica particles as reinforcing agents on the structural and mechanical properties of polystyrene-poly(ethylene/butylene)-polystyrene (PS-PEB-PS) triblock gel has been investigated. Different types of chemically modified silica have been compared in order...

  2. Effect of silica concentration on electrical conductivity of epoxy resin-carbon black-silica nanocomposites

    International Nuclear Information System (INIS)

    Zhang Wei; Blackburn, Richard S.; Dehghani-Sanij, Abbas A.

    2007-01-01

    Electrical properties of nanocomposites are determined by the conductive paths of carbon black and influenced by a 'network' of silica. With increasing content of silica, carbon black (CB) particles are optimally dispersed, contributing to the generation of a conductive network between CB particles via direct particle contact and a tunneling effect; maximum conductivity for the epoxy resin-CB-silica nanocomposite described herein occurs at a ratio of 0.6:1.0 (SiO 2 :CB). As a non-conductive component, excessive silica will prevent electron flow, giving rise to low conductivity

  3. RR Tel: Getting Under the Flux Limit: An Observation with FUSE

    Science.gov (United States)

    Sonnenborn, George (Technical Monitor); Kenyon, Scott J.

    2004-01-01

    The goal of this program is to acquire a FUSE spectrum of the symbiotic binary RR Tel. With these data, we plan to derive improved constraints on the hot component, the nebula, and perhaps the red giant wind. Based on results from AG Dra, we should also be able to use some line detections to improve atomic parameters for high ionization emission lines. This results would benefit the general FUSE community. As of this writing, the FUSE observation of RR Tel has not been made. Because RR Tel is a very bright UV source, the FUSE team is assessing the likelihood that RR Tel will have an adverse affect on the instrument.

  4. Liquefier Dynamics in Fused Deposition

    DEFF Research Database (Denmark)

    Bellini, Anna; Guceri, Selcuk; Bertoldi, Maurizio

    2004-01-01

    Layered manufacturing (LM) is an evolution of rapid prototyping (RP) technology whereby a part is built in layers. Fused deposition modeling (FDM) is a particular LM technique in which each section is fabricated through vector style deposition of building blocks, called roads, which...

  5. Silica particles and method of preparation thereof

    NARCIS (Netherlands)

    2015-01-01

    The invention is in the field of silica products. More in particular, the invention is in the field of amorphous silica particles. The invention is directed to amorphous silica particles and related products including clusters of said silica particles, a suspension of said silica particles, and an

  6. Dynamic Aperture Measurements at the Advanced Light Source

    International Nuclear Information System (INIS)

    Decking, W.; Robin, D.

    1999-01-01

    A large dynamic aperture for a storage ring is of importance for long lifetimes and a high injection efficiency. Measurements of the dynamic aperture of the third generation synchrotron light source Advanced Light Source (ALS) using beam excitation with kicker magnets are presented. The experiments were done for various accelerator conditions, allowing us to investigate the influence of different working points, chromaticities, insertion devices, etc.. The results are compared both with tracking calculations and a simple model for the dynamic aperture yielding good agreements. This gives us confidence in the predictability of the nonlinear accelerator model. This is especially important for future ALS upgrades as well as new storage ring designs

  7. Singer product apertures—A coded aperture system with a fast decoding algorithm

    International Nuclear Information System (INIS)

    Byard, Kevin; Shutler, Paul M.E.

    2017-01-01

    A new type of coded aperture configuration that enables fast decoding of the coded aperture shadowgram data is presented. Based on the products of incidence vectors generated from the Singer difference sets, we call these Singer product apertures. For a range of aperture dimensions, we compare experimentally the performance of three decoding methods: standard decoding, induction decoding and direct vector decoding. In all cases the induction and direct vector methods are several orders of magnitude faster than the standard method, with direct vector decoding being significantly faster than induction decoding. For apertures of the same dimensions the increase in speed offered by direct vector decoding over induction decoding is better for lower throughput apertures.

  8. Singer product apertures—A coded aperture system with a fast decoding algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Byard, Kevin, E-mail: kevin.byard@aut.ac.nz [School of Economics, Faculty of Business, Economics and Law, Auckland University of Technology, Auckland 1142 (New Zealand); Shutler, Paul M.E. [National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616 (Singapore)

    2017-06-01

    A new type of coded aperture configuration that enables fast decoding of the coded aperture shadowgram data is presented. Based on the products of incidence vectors generated from the Singer difference sets, we call these Singer product apertures. For a range of aperture dimensions, we compare experimentally the performance of three decoding methods: standard decoding, induction decoding and direct vector decoding. In all cases the induction and direct vector methods are several orders of magnitude faster than the standard method, with direct vector decoding being significantly faster than induction decoding. For apertures of the same dimensions the increase in speed offered by direct vector decoding over induction decoding is better for lower throughput apertures.

  9. COOH-functionalisation of silica particles

    Energy Technology Data Exchange (ETDEWEB)

    Majewski, Peter, E-mail: peter.majewski@unisa.edu.au [School of Advanced Manufacturing and Mechanical Engineering, Mawson Institute, University of South Australia, Adelaide (Australia); Albrecht, Trent [Ian Wark Research Institute, University of South Australia, Adelaide (Australia); Weber, Siegfried [Department of Biotechnology, University of Applied Sciences, Mannheim (Germany)

    2011-09-01

    In this study COOH-functionalised silica is synthesised using phosphonateN-(phosphonomethyl)iminodiacetic acid (PMIDA) in an aqueous solution. The presence of PMIDA on the silica particles was verified using Fourier Transform Infrared Spectroscopy, X-ray Photoelectron Spectroscopy and titration. Experimentally, surface concentrations of COOH functional groups of up to about 3 mmol/g{sub silica} were achieved, whereas theoretical calculation of the maximum COOH functional group concentration gave about 1 mmol/g{sub silica}. The discrepancy may be caused by PMIDA multilayer formation on the particle.

  10. Technological aspects of using protective fuses in low-voltage mine networks

    Energy Technology Data Exchange (ETDEWEB)

    Kowalski, Z; Pudelko, H

    1986-04-01

    Protection systems are evaluated for mining equipment used in underground coal mining in Poland. Operation of contactor switches is analyzed. Systems for protection of vacuum contactor switches from overload are comparatively evaluated. Types of current reducers are reviewed. Design of the aM protection fuse which is activated only when overload current exceeds the limiting level is analyzed. Protection fuses with the aM characteristic meeting IEC and VDE requirements for fuses used in SV5, SV7 and SV8 vacuum contactors for power networks of up to 1000 V are evaluated. Characteristics of the vacuum contactors manufactured in Poland are given in 6 diagrams and 2 tables. Reliability of the vacuum contactors with aM protection fuses is analyzed. 8 references.

  11. Self characterization of a coded aperture array for neutron source imaging

    Energy Technology Data Exchange (ETDEWEB)

    Volegov, P. L., E-mail: volegov@lanl.gov; Danly, C. R.; Guler, N.; Merrill, F. E.; Wilde, C. H. [Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States); Fittinghoff, D. N. [Livermore National Laboratory, Livermore, California 94550 (United States)

    2014-12-15

    The neutron imaging system at the National Ignition Facility (NIF) is an important diagnostic tool for measuring the two-dimensional size and shape of the neutrons produced in the burning deuterium-tritium plasma during the stagnation stage of inertial confinement fusion implosions. Since the neutron source is small (∼100 μm) and neutrons are deeply penetrating (>3 cm) in all materials, the apertures used to achieve the desired 10-μm resolution are 20-cm long, triangular tapers machined in gold foils. These gold foils are stacked to form an array of 20 apertures for pinhole imaging and three apertures for penumbral imaging. These apertures must be precisely aligned to accurately place the field of view of each aperture at the design location, or the location of the field of view for each aperture must be measured. In this paper we present a new technique that has been developed for the measurement and characterization of the precise location of each aperture in the array. We present the detailed algorithms used for this characterization and the results of reconstructed sources from inertial confinement fusion implosion experiments at NIF.

  12. The chaotic dynamical aperture

    International Nuclear Information System (INIS)

    Lee, S.Y.; Tepikian, S.

    1985-01-01

    Nonlinear magnetic forces become more important for particles in the modern large accelerators. These nonlinear elements are introduced either intentionally to control beam dynamics or by uncontrollable random errors. Equations of motion in the nonlinear Hamiltonian are usually non-integrable. Because of the nonlinear part of the Hamiltonian, the tune diagram of accelerators is a jungle. Nonlinear magnet multipoles are important in keeping the accelerator operation point in the safe quarter of the hostile jungle of resonant tunes. Indeed, all the modern accelerator design have taken advantages of nonlinear mechanics. On the other hand, the effect of the uncontrollable random multipoles should be evaluated carefully. A powerful method of studying the effect of these nonlinear multipoles is using a particle tracking calculation, where a group of test particles are tracing through these magnetic multipoles in the accelerator hundreds to millions of turns in order to test the dynamical aperture of the machine. These methods are extremely useful in the design of a large accelerator such as SSC, LEP, HERA and RHIC. These calculations unfortunately take tremendous amount of computing time. In this paper, we try to apply the existing method in the nonlinear dynamics to study the possible alternative solution. When the Hamiltonian motion becomes chaotic, the tune of the machine becomes undefined. The aperture related to the chaotic orbit can be identified as chaotic dynamical aperture. We review the method of determining chaotic orbit and apply the method to nonlinear problems in accelerator physics. We then discuss the scaling properties and effect of random sextupoles

  13. Variable aperture-based ptychographical iterative engine method

    Science.gov (United States)

    Sun, Aihui; Kong, Yan; Meng, Xin; He, Xiaoliang; Du, Ruijun; Jiang, Zhilong; Liu, Fei; Xue, Liang; Wang, Shouyu; Liu, Cheng

    2018-02-01

    A variable aperture-based ptychographical iterative engine (vaPIE) is demonstrated both numerically and experimentally to reconstruct the sample phase and amplitude rapidly. By adjusting the size of a tiny aperture under the illumination of a parallel light beam to change the illumination on the sample step by step and recording the corresponding diffraction patterns sequentially, both the sample phase and amplitude can be faithfully reconstructed with a modified ptychographical iterative engine (PIE) algorithm. Since many fewer diffraction patterns are required than in common PIE and the shape, the size, and the position of the aperture need not to be known exactly, this proposed vaPIE method remarkably reduces the data acquisition time and makes PIE less dependent on the mechanical accuracy of the translation stage; therefore, the proposed technique can be potentially applied for various scientific researches.

  14. Performance limits of ion extraction systems with non-circular apertures

    Energy Technology Data Exchange (ETDEWEB)

    Shagayda, A., E-mail: shagayda@gmail.com; Madeev, S. [Keldysh Research Centre, Onezhskaya, 8, 125438 Moscow (Russian Federation)

    2016-04-15

    A three-dimensional computer simulation is used to determine the perveance limitations of ion extraction systems with non-circular apertures. The objective of the study is to analyze the possibilities to improve mechanical strength of the ion optics made of carbon-carbon composite materials. Non-circular grid apertures are better suited to the physical structure of carbon-carbon composite materials, than conventionally used circular holes in a hexagonal pattern, because they allow a fewer number of cut fibers. However, the slit-type accelerating systems, usually regarded as the main alternative to the conventional ion optics, have an intolerably narrow range of operating perveance values at which there is no direct ion impingement on the acceleration grid. This paper presents results of comparative analysis of a number of different ion optical systems with non-circular apertures and conventional ion optical systems with circular apertures. It has been revealed that a relatively wide perveance range without direct ion impingement may be obtained with apertures shaped as a square with rounded corners. Numerical simulations show that this geometry may have equivalent perveance range as the traditional geometry with circular apertures while being more mechanically robust. In addition, such important characteristics, as the effective transparency for both the ions and the neutral atoms, the height of the potential barrier reflecting the downstream plasma electrons and the angular divergence of the beamlet also can be very close to these parameters for the optics with circular apertures.

  15. Performance limits of ion extraction systems with non-circular apertures.

    Science.gov (United States)

    Shagayda, A; Madeev, S

    2016-04-01

    A three-dimensional computer simulation is used to determine the perveance limitations of ion extraction systems with non-circular apertures. The objective of the study is to analyze the possibilities to improve mechanical strength of the ion optics made of carbon-carbon composite materials. Non-circular grid apertures are better suited to the physical structure of carbon-carbon composite materials, than conventionally used circular holes in a hexagonal pattern, because they allow a fewer number of cut fibers. However, the slit-type accelerating systems, usually regarded as the main alternative to the conventional ion optics, have an intolerably narrow range of operating perveance values at which there is no direct ion impingement on the acceleration grid. This paper presents results of comparative analysis of a number of different ion optical systems with non-circular apertures and conventional ion optical systems with circular apertures. It has been revealed that a relatively wide perveance range without direct ion impingement may be obtained with apertures shaped as a square with rounded corners. Numerical simulations show that this geometry may have equivalent perveance range as the traditional geometry with circular apertures while being more mechanically robust. In addition, such important characteristics, as the effective transparency for both the ions and the neutral atoms, the height of the potential barrier reflecting the downstream plasma electrons and the angular divergence of the beamlet also can be very close to these parameters for the optics with circular apertures.

  16. Performance limits of ion extraction systems with non-circular apertures

    Science.gov (United States)

    Shagayda, A.; Madeev, S.

    2016-04-01

    A three-dimensional computer simulation is used to determine the perveance limitations of ion extraction systems with non-circular apertures. The objective of the study is to analyze the possibilities to improve mechanical strength of the ion optics made of carbon-carbon composite materials. Non-circular grid apertures are better suited to the physical structure of carbon-carbon composite materials, than conventionally used circular holes in a hexagonal pattern, because they allow a fewer number of cut fibers. However, the slit-type accelerating systems, usually regarded as the main alternative to the conventional ion optics, have an intolerably narrow range of operating perveance values at which there is no direct ion impingement on the acceleration grid. This paper presents results of comparative analysis of a number of different ion optical systems with non-circular apertures and conventional ion optical systems with circular apertures. It has been revealed that a relatively wide perveance range without direct ion impingement may be obtained with apertures shaped as a square with rounded corners. Numerical simulations show that this geometry may have equivalent perveance range as the traditional geometry with circular apertures while being more mechanically robust. In addition, such important characteristics, as the effective transparency for both the ions and the neutral atoms, the height of the potential barrier reflecting the downstream plasma electrons and the angular divergence of the beamlet also can be very close to these parameters for the optics with circular apertures.

  17. Performance limits of ion extraction systems with non-circular apertures

    International Nuclear Information System (INIS)

    Shagayda, A.; Madeev, S.

    2016-01-01

    A three-dimensional computer simulation is used to determine the perveance limitations of ion extraction systems with non-circular apertures. The objective of the study is to analyze the possibilities to improve mechanical strength of the ion optics made of carbon-carbon composite materials. Non-circular grid apertures are better suited to the physical structure of carbon-carbon composite materials, than conventionally used circular holes in a hexagonal pattern, because they allow a fewer number of cut fibers. However, the slit-type accelerating systems, usually regarded as the main alternative to the conventional ion optics, have an intolerably narrow range of operating perveance values at which there is no direct ion impingement on the acceleration grid. This paper presents results of comparative analysis of a number of different ion optical systems with non-circular apertures and conventional ion optical systems with circular apertures. It has been revealed that a relatively wide perveance range without direct ion impingement may be obtained with apertures shaped as a square with rounded corners. Numerical simulations show that this geometry may have equivalent perveance range as the traditional geometry with circular apertures while being more mechanically robust. In addition, such important characteristics, as the effective transparency for both the ions and the neutral atoms, the height of the potential barrier reflecting the downstream plasma electrons and the angular divergence of the beamlet also can be very close to these parameters for the optics with circular apertures.

  18. Metal-silica sol-gel materials

    Science.gov (United States)

    Stiegman, Albert E. (Inventor)

    2002-01-01

    The present invention relates to a single phase metal-silica sol-gel glass formed by the co-condensation of a transition metal with silicon atoms where the metal atoms are uniformly distributed within the sol-gel glass as individual metal centers. Any transition metal may be used in the sol-gel glasses. The present invention also relates to sensor materials where the sensor material is formed using the single phase metal-silica sol-gel glasses. The sensor materials may be in the form of a thin film or may be attached to an optical fiber. The present invention also relates to a method of sensing chemicals using the chemical sensors by monitoring the chromatic change of the metal-silica sol-gel glass when the chemical binds to the sensor. The present invention also relates to oxidation catalysts where a metal-silica sol-gel glass catalyzes the reaction. The present invention also relates to a method of performing oxidation reactions using the metal-silica sol-gel glasses. The present invention also relates to organopolymer metal-silica sol-gel composites where the pores of the metal-silica sol-gel glasses are filled with an organic polymer polymerized by the sol-gel glass.

  19. High-contrast visible nulling coronagraph for segmented and arbitrary telescope apertures

    Science.gov (United States)

    Hicks, Brian A.; Lyon, Richard G.; Bolcar, Matthew R.; Clampin, Mark; Petrone, Peter

    2014-08-01

    Exoplanet coronagraphy will be driven by the telescope architectures available and thus the system designer must have available one or more suitable coronagraphic instrument choices that spans the set of telescope apertures, including filled (off-axis), obscured (e.g. with secondary mirror spiders and struts), segmented apertures, such as JWST, and interferometric apertures. In this work we present one such choice of coronagraph, known as the visible nulling coronagraph (VNC), that spans all four types of aperture and also employs differential sensing and control.

  20. Full spectrum endoscopy (FUSE) versus standard forward-viewing endoscope (SFV) in a high-risk population

    DEFF Research Database (Denmark)

    Roepstorff, Søren; Hadi, Sabah Anwar; Rasmussen, Morten

    2017-01-01

    OBJECTIVES: To investigate the diagnostic performance of Full Spectrum Endoscopy (FUSE) compared to a conventional standard forward-viewing endoscope (SFV). The primary outcome was adenoma detection rate (ADR) and mean adenoma detection. Secondary outcome was feasibility of FUSE opposed to SFV...... intubation time, fentanyl and midazolam sedation, CRC detection, ADR, diverticulosis, bowel preparation, patient discomfort and endoscopist difficulty rating. Participants underwent FUSE colonoscopy on days when the FUSE system was available, while the remaining participants had SFV. All colonoscopies were.......1 ± 6.2 min in the FUSE and SFV groups (p = .040). ADR was 67.0% and 59.6% (p = .097), while the mean adenoma detection was 1.79 and 1.38 (p = .022) in the FUSE and SFV groups. Endoscopists reported increased difficulty rating with FUSE compared to SFV (p > .001). CONCLUSION: FUSE colonoscopy provides...

  1. Ships as salient objects in synthetic aperture radar imaginary

    CSIR Research Space (South Africa)

    Schwegmann, Colin P

    2016-07-01

    Full Text Available The widespread access to Synthetic Aperture Radar data has created a need for more precise ship extraction, specifically in low-to-medium resolution imagery. While Synthetic Aperture Radar pixel resolution is improving for a large swaths...

  2. Electromagnetic Formation Flight (EMFF) for Sparse Aperture Arrays

    Science.gov (United States)

    Kwon, Daniel W.; Miller, David W.; Sedwick, Raymond J.

    2004-01-01

    Traditional methods of actuating spacecraft in sparse aperture arrays use propellant as a reaction mass. For formation flying systems, propellant becomes a critical consumable which can be quickly exhausted while maintaining relative orientation. Additional problems posed by propellant include optical contamination, plume impingement, thermal emission, and vibration excitation. For these missions where control of relative degrees of freedom is important, we consider using a system of electromagnets, in concert with reaction wheels, to replace the consumables. Electromagnetic Formation Flight sparse apertures, powered by solar energy, are designed differently from traditional propulsion systems, which are based on V. This paper investigates the design of sparse apertures both inside and outside the Earth's gravity field.

  3. Exo-planet Direct Imaging with On-Axis and/or Segmented Apertures in Space: Adaptive Compensation of Aperture Discontinuities

    Science.gov (United States)

    Soummer, Remi

    Capitalizing on a recent breakthrough in wavefront control theory for obscured apertures made by our group, we propose to demonstrate a method to achieve high contrast exoplanet imaging with on-axis obscured apertures. Our new algorithm, which we named Adaptive Compensation of Aperture Discontinuities (ACAD), provides the ability to compensate for aperture discontinuities (segment gaps and/or secondary mirror supports) by controlling deformable mirrors in a nonlinear wavefront control regime not utilized before but conceptually similar to the beam reshaping used in PIAA coronagraphy. We propose here an in-air demonstration at 1E- 7 contrast, enabled by adding a second deformable mirror to our current test-bed. This expansion of the scope of our current efforts in exoplanet imaging technologies will enabling us to demonstrate an integrated solution for wavefront control and starlight suppression on complex aperture geometries. It is directly applicable at scales from moderate-cost exoplanet probe missions to the 2.4 m AFTA telescopes to future flagship UVOIR observatories with apertures potentially 16-20 m. Searching for nearby habitable worlds with direct imaging is one of the top scientific priorities established by the Astro2010 Decadal Survey. Achieving this ambitious goal will require 1e-10 contrast on a telescope large enough to provide angular resolution and sensitivity to planets around a significant sample of nearby stars. Such a mission must of course also be realized at an achievable cost. Lightweight segmented mirror technology allows larger diameter optics to fit in any given launch vehicle as compared to monolithic mirrors, and lowers total life-cycle costs from construction through integration & test, making it a compelling option for future large space telescopes. At smaller scales, on-axis designs with secondary obscurations and supports are less challenging to fabricate and thus more affordable than the off-axis unobscured primary mirror designs

  4. Silica aerogel Cerenkov counter

    International Nuclear Information System (INIS)

    Yasumi, S.; Masaike, A.; Yamamoto, A.; Yoshimura, Y.; Kawai, H.

    1984-03-01

    In order to obtain silica aerogel radiators of good quality, the prescription used by Saclay group has been developed. We have done several experiments using beams from KEK.PS to test the performance of a Cerenkov counter with aerogel modules produced in KEK. It turned out that these modules had excellent quality. The production rate of silica aerogel in KEK is 15 -- 20 litres a week. Silica aerogel modules of 20 x 10 x 3 cm 3 having the refractive index of 1.058 are successfully being used by Kyoto University group in the KEK experiment E92 (Σ). Methodes to produce silica aerogel with higher refractive index than 1.06 has been investigated both by heating an module with the refractive index of 1.06 and by hydrolyzing tetraethyl silicate. (author)

  5. Hybrid Z-Θ Pinches with fused capacitor banks

    International Nuclear Information System (INIS)

    Grandey, R.; Gersten, M.; Loter, N.; Rauch, J.; Rostoker, N.; Thompson, W.; Ware, K.

    1987-01-01

    The Hybrid Z-Θ Pinch circuit equations in the thin shell model were reexamined to see what advantages can be obtained by using a fused, high-energy (>--1MJ) bank driver. The DNA ACE facility at MLI utilizes a 36 μF capacitor band which can be charged to 120 kV to provide 250 kJ of stored energy. This configuration appears to be very appropriate to test the performance of a hybrid-stabilized fused-bank driven pinch. The circuit analyses suggest that the energy transfer efficiency from the bank to a pinched plasma can be increased from less than 1%, for a nonfused bank, to about 10% for a fused configuration. In the applicable region of parameter space, the Hybrid Pinch does not increase the efficiency of energy transfer into the plasma over that obtainable from a Z-pinch. The additional stability may allow larger initial radii to be used with concomitant improved coupling into radiation above 1 keV

  6. Melt flow and mechanical properties of silica/perfluoropolymer nanocomposites Fabricated by direct melt-compounding without surface modification on nano-silica.

    Science.gov (United States)

    Tanahashi, Mitsuru; Watanabe, Yusuke; Lee, Jeong-Chang; Takeda, Kunihiko; Fujisawa, Toshiharu

    2009-01-01

    The authors have previously developed a novel method for the fabrication of silica/perfluoropolymer nanocomposites, wherein nano-sized silica particles without surface modification were dispersed uniformly through breakdown of loosely packed agglomerates of silica nanoparticles with low fracture strength in a polymer melt during direct melt-compounding. The method consists of two stages; the first stage involves preparation of the loose silica agglomerate, and the second stage involves melt-compounding of a completely hydrophobic perfluoropolymer, PFA (poly(tetrafluoroethylene-co-perfluoropropylvinylether)), with the loose silica agglomerates. By using this simple method without any lipophilic treatment of the silica surfaces, silica nanoparticles with a primary diameter of 190 nm could be dispersed uniformly into the PFA matrix. The main purpose of the present study is to evaluate the melt flow and tensile properties of silica/PFA nanocomposites fabricated by the above method. In order to elucidate the effects of the size of the dispersed silica in the PFA matrix on the properties of the composites, silica/PFA composite samples exhibiting the dispersion of larger-sized silica particle-clusters were fabricated as negative controls of the silica dispersion state. The results obtained under the present experimental conditions showed that the size of the dispersed silica in the PFA matrix exerts a strong influence on the ultimate tensile properties, such as tensile strength and elongation at break, and the melt flow rate (MFR) of the composite materials. The MFR of the silica/PFA nanocomposite became higher than that of the pure PFA without silica addition, although the MFR of the PFA composites containing larger silica particle-clusters became much lower than that of the pure PFA. Furthermore, uniform dispersion of isolated silica nanoparticles was found to improve not only the Young's modulus but also the ultimate tensile properties of the composite.

  7. Synthetic aperture radar capabilities in development

    Energy Technology Data Exchange (ETDEWEB)

    Miller, M. [Lawrence Livermore National Lab., CA (United States)

    1994-11-15

    The Imaging and Detection Program (IDP) within the Laser Program is currently developing an X-band Synthetic Aperture Radar (SAR) to support the Joint US/UK Radar Ocean Imaging Program. The radar system will be mounted in the program`s Airborne Experimental Test-Bed (AETB), where the initial mission is to image ocean surfaces and better understand the physics of low grazing angle backscatter. The Synthetic Aperture Radar presentation will discuss its overall functionality and a brief discussion on the AETB`s capabilities. Vital subsystems including radar, computer, navigation, antenna stabilization, and SAR focusing algorithms will be examined in more detail.

  8. Multifunctional nanomedicine with silica: Role of silica in nanoparticles for theranostic, imaging, and drug monitoring.

    Science.gov (United States)

    Chen, Fang; Hableel, Ghanim; Zhao, Eric Ruike; Jokerst, Jesse V

    2018-07-01

    The idea of multifunctional nanomedicine that enters the human body to diagnose and treat disease without major surgery is a long-standing dream of nanomaterials scientists. Nanomaterials show incredible properties that are not found in bulk materials, but achieving multi-functionality on a single material remains challenging. Integrating several types of materials at the nano-scale is critical to the success of multifunctional nanomedicine device. Here, we describe the advantages of silica nanoparticles as a tool for multifunctional nano-devices. Silica nanoparticles have been intensively studied in drug delivery due to their biocompatibility, degradability, tunable morphology, and ease of modification. Moreover, silica nanoparticles can be integrated with other materials to obtain more features and achieve theranostic capabilities and multimodality for imaging applications. In this review, we will first compare the properties of silica nanoparticles with other well-known nanomaterials for bio-applications and describe typical routes to synthesize and integrate silica nanoparticles. We will then highlight theranostic and multimodal imaging application that use silica-based nanoparticles with a particular interest in real-time monitoring of therapeutic molecules. Finally, we will present the challenges and perspective on future work with silica-based nanoparticles in medicine. Copyright © 2018 Elsevier Inc. All rights reserved.

  9. Detecting alkali-silica reaction in thick concrete structures using linear array ultrasound

    Science.gov (United States)

    Bull Ezell, N. Dianne; Albright, Austin; Clayton, Dwight; Santos-Villalobos, Hector

    2018-03-01

    Commercial nuclear power plants (NPPs) depend heavily on concrete structures, making the long-term performance of these structures crucial for safe operation, especially with license period extensions to 60 years and possibly beyond. Alkali-silica reaction (ASR) is a reaction that occurs over time in concrete between alkaline cement paste and reactive, noncrystalline silica (aggregates). In the presence of water, an expansive gel is formed within the aggregates, which results in microcracks in aggregates and adjacent cement paste. ASR can potentially affect concrete properties and performance characteristics such as compressive strength, modulus of elasticity, flexural stiffness, shear strength, and tensile strength. Currently, no nondestructive evaluation methods have proven effective in identifying ASR before surface cracks form. ASR is identified visibly or by petrographic analysis. Although ASR definitely impacts concrete material properties, the performance of concrete structures exhibiting ASR depends on whether or not the concrete is unconfined or confined with reinforcing bars. Confinement by reinforcing bars restrainsthe expansion of ASR-affected concrete, similar to prestressing, thus improving the performance of a structure. Additionally, there is no direct correlation between the mechanical properties of concrete sample cores and the in-situ properties of the concrete. The University of Tennessee-Knoxville, Oak Ridge National Laboratory, and a consortium of universities have developed an accelerated ASR experiment. Three large concrete specimens, representative of NPP infrastructure, were constructed containing both embedded and surface instruments. This paper presents preliminary analysis of these specimens using a frequency-banded synthetic aperture focusing technique.

  10. Aperture referral in dioptric systems with stigmatic elements

    Directory of Open Access Journals (Sweden)

    W. F. Harris

    2012-12-01

    Full Text Available A previous paper develops the general theory of aperture referral in linear optics and shows how several ostensibly distinct concepts, including the blur patch on the retina, the effective corneal patch, the projective field and the field of view, are now unified as particular applications of the general theory.  The theory allows for astigmatism and heterocentricity.  Symplecticity and the generality of the approach, however, make it difficult to gain insight and mean that the material is not accessible to readers unfamiliar with matrices and linear algebra. The purpose of this paper is to examine whatis, perhaps, the most important special case, that in which astigmatism is ignored.  Symplecticity and, hence, the mathematics become greatly simplified. The mathematics reduces largely to elementary vector algebra and, in some places, simple scalar algebra and yet retains the mathematical form of the general approach.  As a result the paper allows insight into and provides a stepping stone to the general theory.  Under referral an aperture under-goes simple scalar magnification and transverse translation.  The paper pays particular attention to referral to transverse planes in the neighbourhood of a focal point where the magnification may be positive, zero or negative.  Circular apertures are treated as special cases of elliptical apertures and the meaning of referred apertures of negative radius is explained briefly. (S Afr Optom 2012 71(1 3-11

  11. Limited aperture effects on ultrasonic image reconstruction

    International Nuclear Information System (INIS)

    Kogan, V.G.; Rose, J.H.

    1985-01-01

    In the inverse Born approximation the shape of a weak scatterer can be determined from a knowledge of the backscattered ultrasonic amplitude for all directions of incidence and all frequencies. Two questions are considered. First, what information on the scatterer shape is preserved and what is degraded if the scattering data are available only within a limited set of incident directions (limited aperture). This problem is addressed for a spherical weakly scattering uniform flaw. It is shown that the problem of a general uniform ellipsoidal flaw can be reduced to the spherical case by a scale transformation; however, the apertures in these two cases must be related by the same transformation. Second, limited aperture and finite bandwidth Born inversions were performed for strongly scattering flaws (voids and cracks) using numerically generated scattering amplitudes. These inversions were then compared with the weak scattering analytic results, which show many common features

  12. Variable aperture-based ptychographical iterative engine method.

    Science.gov (United States)

    Sun, Aihui; Kong, Yan; Meng, Xin; He, Xiaoliang; Du, Ruijun; Jiang, Zhilong; Liu, Fei; Xue, Liang; Wang, Shouyu; Liu, Cheng

    2018-02-01

    A variable aperture-based ptychographical iterative engine (vaPIE) is demonstrated both numerically and experimentally to reconstruct the sample phase and amplitude rapidly. By adjusting the size of a tiny aperture under the illumination of a parallel light beam to change the illumination on the sample step by step and recording the corresponding diffraction patterns sequentially, both the sample phase and amplitude can be faithfully reconstructed with a modified ptychographical iterative engine (PIE) algorithm. Since many fewer diffraction patterns are required than in common PIE and the shape, the size, and the position of the aperture need not to be known exactly, this proposed vaPIE method remarkably reduces the data acquisition time and makes PIE less dependent on the mechanical accuracy of the translation stage; therefore, the proposed technique can be potentially applied for various scientific researches. (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

  13. Synthetic aperture tissue and flow ultrasound imaging

    DEFF Research Database (Denmark)

    Nikolov, Svetoslav

    imaging applied to medical ultrasound. It is divided into two major parts: tissue and blood flow imaging. Tissue imaging using synthetic aperture algorithms has been investigated for about two decades, but has not been implemented in medical scanners yet. Among the other reasons, the conventional scanning...... and beamformation methods are adequate for the imaging modalities in clinical use - the B-mode imaging of tissue structures, and the color mapping of blood flow. The acquisition time, however, is too long, and these methods fail to perform real-time three-dimensional scans. The synthetic transmit aperture......, on the other hand, can create a Bmode image with as little as 2 emissions, thus significantly speeding-up the scan procedure. The first part of the dissertation describes the synthetic aperture tissue imaging. It starts with an overview of the efforts previously made by other research groups. A classification...

  14. Study of the pluronic-silica interaction in synthesis of mesoporous silica under mild acidic conditions.

    Science.gov (United States)

    Sundblom, Andreas; Palmqvist, Anders E C; Holmberg, Krister

    2010-02-02

    The interaction between silica and poly(ethylene oxide) (PEO) in water may appear trivial and it is generally stated that hydrogen bonding is responsible for the attraction. However, a literature search shows that there is not a consensus with respect to the mechanism behind the attractive interaction. Several papers claim that only hydrogen bonding is not sufficient to explain the binding. The silica-PEO interaction is interesting from an academic perspective and it is also exploited in the preparation of mesoporous silica, a material of considerable current interest. This study concerns the very early stage of synthesis of mesoporous silica under mild acidic conditions, pH 2-5, and the aim is to shed light on the interaction between silica and the PEO-containing structure directing agent. The synthesis comprises two steps. An organic silica source, tetraethylorthosilicate (TEOS), is first hydrolyzed and Pluronic P123, a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) block copolymer, is subsequently added at different time periods following the hydrolysis of TEOS. It is shown that the interaction between the silica and the Pluronic is dependent both on the temperature and on the time between onset of TEOS hydrolysis and addition of the copolymer. The results show that the interaction is mainly driven by entropy. The effect of the synthesis temperature and of the time between hydrolysis and addition of the copolymer on the final material is also studied. The material with the highest degree of mesoorder was obtained when the reaction was performed at 20 degrees C and the copolymer was added 40 h after the start of TEOS hydrolysis. It is claimed that the reason for the good ordering of the silica is that whereas particle formation under these conditions is fast, the rate of silica condensation is relatively low.

  15. Exploding metallic fuse physics experiments

    International Nuclear Information System (INIS)

    Goforth, J.H.; Hackett, K.E.; Lindemuth, I.R.; Lopez, E.A.; McCullough, W.F.; Dona, H.; Reinovsky, R.E.

    1986-01-01

    The ultimate practicality of inductive pulse compression systems as drivers for energetic plasma implosions hinges on the development of a suitable opening switch capable of interrupting tons of megamp currents in time scales of a few hundred nanoseconds while withstanding L(dI/dt) voltages of a megavolt or more. 1. Exploding metallic foils (fuses) are a candidate for switching elements in the inductive store pulsed power systems used in the Los Alamos and Air Force Weapons Laboratory foil implosion X-ray source generation programs. To verify or modify new theoretical and computational predictions about the electrical and hydrodynamic behavior of exploding metallic foils used as fuses. The authors have initiated a new series of small scale capacitor bank driven fuse experiments. The experiments represent an extension of previous experiments, but in the new series a foil geometry more amenable to theoretical and computational analysis is used. The metallic foil (aluminum or copper) is laminated between two thin layers of insulating material (mylar or kaptan). Adjacent to one layer of insulation is a much heavier backing insulator (polyethylene) whereas air is adjacent to the other layer. Because of the differing masses on the two sides of the foil, the foil expansion and hydrodynamic motion is essentially one-sided and the layer of insulation on the expanding side becomes a readily-characterizable ''flyer'' which provides a controlled amount of hydrodynamic tamping. In addition to the usual voltage, current, and dI/dt electrical measurements, time-resolved spectrometer measurements are used to determine the temperature of the expanding metallic foil. Post-shot examination of the flyer and the insulation impacted by the flyer gives insight into the experimental behavior

  16. Silica coatings on clarithromycin.

    Science.gov (United States)

    Bele, Marjan; Dmitrasinovic, Dorde; Planinsek, Odon; Salobir, Mateja; Srcic, Stane; Gaberscek, Miran; Jamnik, Janko

    2005-03-03

    Pre-crystallized clarithromycin (6-O-methylerythromycin A) particles were coated with silica from the tetraethyl orthosilicate (TEOS)-ethanol-aqueous ammonia system. The coatings had a typical thickness of 100-150 nm and presented about 15 wt.% of the silica-drug composite material. The properties of the coatings depended on reactant concentration, temperature and mixing rate and, in particular, on the presence of a cationic surfactant (cetylpyridinium chloride). In the presence of cetylpyridinium chloride the silica coatings slightly decreased the rate of pure clarithromycin dissolution.

  17. Oxygen configurations in silica

    International Nuclear Information System (INIS)

    Chelikowsky, James R.; Chadi, D. J.; Binggeli, N.

    2000-01-01

    We propose a transition state for oxygen in silica. This state is produced by the insertion of an oxygen molecule into the Si-O-Si bond, i.e., it consists of producing a Si-O-O-O-Si bond. This state allows molecular oxygen diffusion in silica without breaking the molecular O 2 bond and it is energetically more stable than a peroxy configuration. This configuration may allow for exchange of molecular oxygen with the oxygen in the silica framework. (c) 2000 The American Physical Society

  18. Autofocus algorithm for synthetic aperture radar imaging with large curvilinear apertures

    Science.gov (United States)

    Bleszynski, E.; Bleszynski, M.; Jaroszewicz, T.

    2013-05-01

    An approach to autofocusing for large curved synthetic aperture radar (SAR) apertures is presented. Its essential feature is that phase corrections are being extracted not directly from SAR images, but rather from reconstructed SAR phase-history data representing windowed patches of the scene, of sizes sufficiently small to allow the linearization of the forward- and back-projection formulae. The algorithm processes data associated with each patch independently and in two steps. The first step employs a phase-gradient-type method in which phase correction compensating (possibly rapid) trajectory perturbations are estimated from the reconstructed phase history for the dominant scattering point on the patch. The second step uses phase-gradient-corrected data and extracts the absolute phase value, removing in this way phase ambiguities and reducing possible imperfections of the first stage, and providing the distances between the sensor and the scattering point with accuracy comparable to the wavelength. The features of the proposed autofocusing method are illustrated in its applications to intentionally corrupted small-scene 2006 Gotcha data. The examples include the extraction of absolute phases (ranges) for selected prominent point targets. They are then used to focus the scene and determine relative target-target distances.

  19. Statistical measurement of power spectrum density of large aperture optical component

    International Nuclear Information System (INIS)

    Xu Jiancheng; Xu Qiao; Chai Liqun

    2010-01-01

    According to the requirement of ICF, a method based on statistical theory has been proposed to measure the power spectrum density (PSD) of large aperture optical components. The method breaks the large-aperture wavefront into small regions, and obtains the PSD of the large-aperture wavefront by weighted averaging of the PSDs of the regions, where the weight factor is each region's area. Simulation and experiment demonstrate the effectiveness of the proposed method. They also show that, the obtained PSDs of the large-aperture wavefront by statistical method and sub-aperture stitching method fit well, when the number of small regions is no less than 8 x 8. The statistical method is not sensitive to translation stage's errors and environment instabilities, thus it is appropriate for PSD measurement during the process of optical fabrication. (authors)

  20. The Effect of Various Acids to the Gelation Process to the Silica Gel Characteristic Using Organic Silica

    Science.gov (United States)

    Rahman, NA; Widiyastuti, W.; Sigit, D.; Ajiza, M.; Sujana, W.

    2018-01-01

    Bagasse ash is solid waste of cane sugar industry which contain of silica more than 51%. Some previous study of silica gel from bagasse ash have been conducted often and been applied. This study concerns about the effect of various acid used in the process of gelation to the characteristic of silica gel produced. Then, this silica gel will be used as adsorbent. As that, the silica gel must fulfill the requirements of adsorbent, as have good pores characteristics, fit in mesoporous size so that adsorbent diffusion process is not disturbed. A fitted pores size of silica gel can be prepared by managing acid concentration used. The effect of acid, organic acid (tartaric acid) and inorganic acid (hydrochloric acid), is investigated in detail. The acid is added into sodium silicate solution in that the gel is formed, the pores structures can be investigated with BET, the crystal form is analyzed with XRD and the pore structure is analyzed visually with SEM. By managing the acid concentration added, it gets the effect of acid to the pore structure of silica gel. The bigger concentration is, the bigger the pore’s size of silica gel produced.

  1. Morphological evaluation of maxillary second molars with fused roots: a micro-CT study.

    Science.gov (United States)

    Ordinola-Zapata, R; Martins, J N R; Bramante, C M; Villas-Boas, M H; Duarte, M H; Versiani, M A

    2017-12-01

    To evaluate the internal and external morphologies of fused-rooted maxillary second molars by means of micro-computed tomography (micro-CT) analysis. A total of 100 fused-rooted maxillary second molars from a Brazilian subpopulation were divided into six groups according to the root morphology. The samples were scanned at a resolution of 19.6 μm and evaluated with regard to the external morphology of the roots, the root canal configuration, the percentage frequency of C-shaped canals and isthmuses, as well as the morphology of the root canal system at 1, 2 and 3 mm from the anatomical apex of the fused roots. The most prevalent root canal fusions were type 1, mesiobuccal root fused with distobuccal root (32%), followed by type 3, DB root fused with P root (27%), and type 4, MB root fused with DB root, and P root fused with MB or DB roots (21%). The prevalence of C-shaped root canal systems were 22%. Depending on the type of root fusion, the percentage frequency of isthmuses in the apical level varied from 9.3% to 42.8%, whilst the presence of apical deltas ranged from 18.5% to 57.1% of teeth. The root canal system of maxillary second molars with fused roots may have a high incidence of merging canals, isthmuses, apical deltas and C-shaped configurations. © 2017 International Endodontic Journal. Published by John Wiley & Sons Ltd.

  2. Electro-Deformation of Fused Cells in a Microfluidic Array Device

    Directory of Open Access Journals (Sweden)

    Yan Liu

    2016-11-01

    Full Text Available We present a new method of analyzing the deformability of fused cells in a microfluidic array device. Electrical stresses—generated by applying voltages (4–20 V across discrete co-planar microelectrodes along the side walls of a microfluidic channel—have been used to electro-deform fused and unfused stem cells. Under an electro-deformation force induced by applying an alternating current (AC signal, we observed significant electro-deformation phenomena. The experimental results show that the fused stem cells were stiffer than the unfused stem cells at a relatively low voltage (<16 V. However, at a relatively high voltage, the fused stem cells were more easily deformed than were the unfused stem cells. In addition, the electro-deformation process is modeled based on the Maxwell stress tensor and structural mechanics of cells. The theoretical results show that a positive correlation is found between the deformation of the cell and the applied voltage, which is consistent with the experimental results. Combined with a numerical analysis and experimental study, the results showed that the significant difference of the deformation ratio of the fused and unfused cells is not due to their size difference. This demonstrates that some other properties of cell membranes (such as the membrane structure were also changed in the electrofusion process, in addition to the size modification of that process.

  3. Parameter Optimization of Multi-Element Synthetic Aperture Imaging Systems

    Directory of Open Access Journals (Sweden)

    Vera Behar

    2007-03-01

    Full Text Available In conventional ultrasound imaging systems with phased arrays, the further improvement of lateral resolution requires enlarging of the number of array elements that in turn increases both, the complexity and the cost, of imaging systems. Multi-element synthetic aperture focusing (MSAF systems are a very good alternative to conventional systems with phased arrays. The benefit of the synthetic aperture is in reduction of the system complexity, cost and acquisition time. In a MSAF system considered in the paper, a group of elements transmit and receive signals simultaneously, and the transmit beam is defocused to emulate a single element response. The echo received at each element of a receive sub-aperture is recorded in the computer memory. The process of transmission/reception is repeated for all positions of a transmit sub-aperture. All the data recordings associated with each corresponding pair "transmit-receive sub-aperture" are then focused synthetically producing a low-resolution image. The final high-resolution image is formed by summing of the all low-resolution images associated with transmit/receive sub-apertures. A problem of parameter optimization of a MSAF system is considered in this paper. The quality of imaging (lateral resolution and contrast is expressed in terms of the beam characteristics - beam width and side lobe level. The comparison between the MSAF system described in the paper and an equivalent conventional phased array system shows that the MSAF system acquires images of equivalent quality much faster using only a small part of the power per image.

  4. Refractive index sensors based on the fused tapered special multi-mode fiber

    Science.gov (United States)

    Fu, Xing-hu; Xiu, Yan-li; Liu, Qin; Xie, Hai-yang; Yang, Chuan-qing; Zhang, Shun-yang; Fu, Guang-wei; Bi, Wei-hong

    2016-01-01

    In this paper, a novel refractive index (RI) sensor is proposed based on the fused tapered special multi-mode fiber (SMMF). Firstly, a section of SMMF is spliced between two single-mode fibers (SMFs). Then, the SMMF is processed by a fused tapering machine, and a tapered fiber structure is fabricated. Finally, a fused tapered SMMF sensor is obtained for measuring external RI. The RI sensing mechanism of tapered SMMF sensor is analyzed in detail. For different fused tapering lengths, the experimental results show that the RI sensitivity can be up to 444.517 81 nm/RIU in the RI range of 1.334 9—1.347 0. The RI sensitivity is increased with the increase of fused tapering length. Moreover, it has many advantages, including high sensitivity, compact structure, fast response and wide application range. So it can be used to measure the solution concentration in the fields of biochemistry, health care and food processing.

  5. Determination of the paraxial focal length using Zernike polynomials over different apertures

    Science.gov (United States)

    Binkele, Tobias; Hilbig, David; Henning, Thomas; Fleischmann, Friedrich

    2017-02-01

    The paraxial focal length is still the most important parameter in the design of a lens. As presented at the SPIE Optics + Photonics 2016, the measured focal length is a function of the aperture. The paraxial focal length can be found when the aperture approaches zero. In this work, we investigate the dependency of the Zernike polynomials on the aperture size with respect to 3D space. By this, conventional wavefront measurement systems that apply Zernike polynomial fitting (e.g. Shack-Hartmann-Sensor) can be used to determine the paraxial focal length, too. Since the Zernike polynomials are orthogonal over a unit circle, the aperture used in the measurement has to be normalized. By shrinking the aperture and keeping up with the normalization, the Zernike coefficients change. The relation between these changes and the paraxial focal length are investigated. The dependency of the focal length on the aperture size is derived analytically and evaluated by simulation and measurement of a strong focusing lens. The measurements are performed using experimental ray tracing and a Shack-Hartmann-Sensor. Using experimental ray tracing for the measurements, the aperture can be chosen easily. Regarding the measurements with the Shack-Hartmann- Sensor, the aperture size is fixed. Thus, the Zernike polynomials have to be adapted to use different aperture sizes by the proposed method. By doing this, the paraxial focal length can be determined from the measurements in both cases.

  6. Permeability and dispersivity of variable-aperture fracture systems

    International Nuclear Information System (INIS)

    Tsang, Y.W.; Tsang, C.F.

    1990-01-01

    A number of recent experiments have pointed out the need of including the effects of aperture variation within each fracture in predicting flow and transport properties of fractured media. This paper introduces a new approach in which medium properties, such as the permeability to flow and dispersivity in tracer transport, are correlated to only three statistical parameters describing the fracture aperture probability distribution and the aperture spatial correlation. We demonstrate how saturated permeability and relative permeabilities for flow, as well as dispersion for solute transport in fractures may be calculated. We are in the process of examining the applicability of these concepts to field problems. Results from the evaluation and analysis of the recent Stripa-3D field data are presented. 13 refs., 10 figs

  7. Highly uniform parallel microfabrication using a large numerical aperture system

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zi-Yu; Su, Ya-Hui, E-mail: ustcsyh@ahu.edu.cn, E-mail: dongwu@ustc.edu.cn [School of Electrical Engineering and Automation, Anhui University, Hefei 230601 (China); Zhang, Chen-Chu; Hu, Yan-Lei; Wang, Chao-Wei; Li, Jia-Wen; Chu, Jia-Ru; Wu, Dong, E-mail: ustcsyh@ahu.edu.cn, E-mail: dongwu@ustc.edu.cn [CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei 230026 (China)

    2016-07-11

    In this letter, we report an improved algorithm to produce accurate phase patterns for generating highly uniform diffraction-limited multifocal arrays in a large numerical aperture objective system. It is shown that based on the original diffraction integral, the uniformity of the diffraction-limited focal arrays can be improved from ∼75% to >97%, owing to the critical consideration of the aperture function and apodization effect associated with a large numerical aperture objective. The experimental results, e.g., 3 × 3 arrays of square and triangle, seven microlens arrays with high uniformity, further verify the advantage of the improved algorithm. This algorithm enables the laser parallel processing technology to realize uniform microstructures and functional devices in the microfabrication system with a large numerical aperture objective.

  8. Preparation and characterization of hybrid Nafion/silica and Nafion/silica/PTA membranes for redox flow batteries

    Energy Technology Data Exchange (ETDEWEB)

    Glibin, V.; Pupkevich, V.; Svirko, L.; Karamanev, D. [Western Ontario Univ., London, ON (Canada). Dept. of Biochemical and Chemical Engineering

    2008-07-01

    Redox flow batteries are both efficient and cost-effective. However, the long-term stability of most ion-exchange membranes is limited as a result of the high oxidation rates of ions with high redox potentials. A method of synthesizing multi-component Nafion-silica and Nafion-silica-PTA membranes was presented in this study, which also investigated the electrochemical and ion transport properties of the membranes. Membranes were cast from dimethylformamide (DMFA) solution. The iron ion diffusion kinetics of the Nafion-silica and Nafion-silica PTA membranes were studied by dialysis. Results of the investigation demonstrated that the introduction of silica and phosphotungstic acid (PTA) into the Nafion membrane composition resulted in a significant decrease of ion transfer through the membrane. The addition of PTA also increased membrane permeability to ferric ions. The low iron diffusion coefficient and high ionic conductivity of the Nafion-silica membrane makes it a promising material for use in redox flow batteries. 4 refs., 1 tab., 1 fig.

  9. Electromagnetic field scattering by a triangular aperture.

    Science.gov (United States)

    Harrison, R E; Hyman, E

    1979-03-15

    The multiple Laplace transform has been applied to analysis and computation of scattering by a double triangular aperture. Results are obtained which match far-field intensity distributions observed in experiments. Arbitrary polarization components, as well as in-phase and quadrature-phase components, may be determined, in the transform domain, as a continuous function of distance from near to far-field for any orientation, aperture, and transformable waveform. Numerical results are obtained by application of numerical multiple inversions of the fully transformed solution.

  10. Impact of environmental contamination on laser induced damage of silica optics in Laser MegaJoule

    International Nuclear Information System (INIS)

    Bien-Aime, K.

    2009-11-01

    Laser induced damage impact of molecular contamination on fused polished silica samples in a context of high power laser fusion facility, such as Laser MegaJoule (LMJ) has been studied. One of the possible causes of laser induced degradation of optical component is the adsorption of molecular or particular contamination on optical surfaces. In the peculiar case of LMJ, laser irradiation conditions are a fluence of 10 J/cm 2 , a wavelength of 351 nm, a pulse duration of 3 ns for a single shot/days frequency. Critical compounds have been identified thanks to environmental measurements, analysis of material outgassing, and identification of surface contamination in the critical environments. Experiments of controlled contamination involving these compounds have been conducted in order to understand and model mechanisms of laser damage. Various hypotheses are proposed to explain the damage mechanism. (author)

  11. Silica-Coated Liposomes for Insulin Delivery

    Directory of Open Access Journals (Sweden)

    Neelam Dwivedi

    2010-01-01

    Full Text Available Liposomes coated with silica were explored as protein delivery vehicles for their enhanced stability and improved encapsulation efficiency. Insulin was encapsulated within the fluidic phosphatidylcholine lipid vesicles by thin film hydration at pH 2.5, and layer of silica was formed above lipid bilayer by acid catalysis. The presence of silica coating and encapsulated insulin was identified using confocal and electron microscopy. The native state of insulin present in the formulation was evident from Confocal Micro-Raman spectroscopy. Silica coat enhances the stability of insulin-loaded delivery vehicles. In vivo study shows that these silica coated formulations were biologically active in reducing glucose levels.

  12. Biomineral repair of abalone shell apertures.

    Science.gov (United States)

    Cusack, Maggie; Guo, Dujiao; Chung, Peter; Kamenos, Nicholas A

    2013-08-01

    The shell of the gastropod mollusc, abalone, is comprised of nacre with an outer prismatic layer that is composed of either calcite or aragonite or both, depending on the species. A striking characteristic of the abalone shell is the row of apertures along the dorsal margin. As the organism and shell grow, new apertures are formed and the preceding ones are filled in. Detailed investigations, using electron backscatter diffraction, of the infill in three species of abalone: Haliotis asinina, Haliotis gigantea and Haliotis rufescens reveals that, like the shell, the infill is composed mainly of nacre with an outer prismatic layer. The infill prismatic layer has identical mineralogy as the original shell prismatic layer. In H. asinina and H. gigantea, the prismatic layer of the shell and infill are made of aragonite while in H. rufescens both are composed of calcite. Abalone builds the infill material with the same high level of biological control, replicating the structure, mineralogy and crystallographic orientation as for the shell. The infill of abalone apertures presents us with insight into what is, effectively, shell repair. Copyright © 2013 Elsevier Inc. All rights reserved.

  13. Adjustable liquid aperture to eliminate undesirable light in holographic projection.

    Science.gov (United States)

    Wang, Di; Liu, Chao; Li, Lei; Zhou, Xin; Wang, Qiong-Hua

    2016-02-08

    In this paper, we propose an adjustable liquid aperture to eliminate the undesirable light in a holographic projection. The aperture is based on hydrodynamic actuation. A chamber is formed with a cylindrical tube. A black droplet is filled in the sidewall of the cylinder tube and the outside space is the transparent oil which is immiscible with the black droplet. An ultrathin glass sheet is attached on the bottom substrate of the device and a black shading film is secured to the central area of the glass sheet. By changing the volume of the black droplet, the black droplet will move to the middle or sidewall due to hydrodynamic actuation, so the device can be used as an adjustable aperture. A divergent spherical wave and a solid lens are used to separate the focus planes of the reconstructed image and diffraction beams induced by the liquid crystal on silicon in the holographic projection. Then the aperture is used to eliminate the diffraction beams by adjusting the size of the liquid aperture and the holographic projection does not have undesirable light.

  14. Focusing optical waves with a rotationally symmetric sharp-edge aperture

    Science.gov (United States)

    Hu, Yanwen; Fu, Shenhe; Li, Zhen; Yin, Hao; Zhou, Jianying; Chen, Zhenqiang

    2018-04-01

    While there has been various kinds of patterned structures proposed for wave focusing, these patterned structures usually involve complicated lithographic techniques since the element size of the patterned structures should be precisely controlled in microscale or even nanoscale. Here we propose a new and straightforward method for focusing an optical plane wave in free space with a rotationally symmetric sharp-edge aperture. The focusing phenomenon of wave is realized by superposition of a portion of the higher-order symmetric plane waves generated from the sharp edges of the apertures, in contrast to previously focusing techniques which usually depend on a curved phase. We demonstrate both experimentally and theoretically the focusing effect with a series of apertures having different rotational symmetry, and find that the intensity of the hotspots could be controlled by the symmetric strength of the sharp-edge apertures. The presented results would advance the conventional wisdom that light would diffract in all directions and become expanding when it propagates through an aperture. The proposed method is easy to be processed, and might open potential applications in interferometry, image, and superresolution.

  15. Maximum nondiffracting propagation distance of aperture-truncated Airy beams

    Science.gov (United States)

    Chu, Xingchun; Zhao, Shanghong; Fang, Yingwu

    2018-05-01

    Airy beams have called attention of many researchers due to their non-diffracting, self-healing and transverse accelerating properties. A key issue in research of Airy beams and its applications is how to evaluate their nondiffracting propagation distance. In this paper, the critical transverse extent of physically realizable Airy beams is analyzed under the local spatial frequency methodology. The maximum nondiffracting propagation distance of aperture-truncated Airy beams is formulated and analyzed based on their local spatial frequency. The validity of the formula is verified by comparing the maximum nondiffracting propagation distance of an aperture-truncated ideal Airy beam, aperture-truncated exponentially decaying Airy beam and exponentially decaying Airy beam. Results show that the formula can be used to evaluate accurately the maximum nondiffracting propagation distance of an aperture-truncated ideal Airy beam. Therefore, it can guide us to select appropriate parameters to generate Airy beams with long nondiffracting propagation distance that have potential application in the fields of laser weapons or optical communications.

  16. Research on precision grinding technology of large scale and ultra thin optics

    Science.gov (United States)

    Zhou, Lian; Wei, Qiancai; Li, Jie; Chen, Xianhua; Zhang, Qinghua

    2018-03-01

    The flatness and parallelism error of large scale and ultra thin optics have an important influence on the subsequent polishing efficiency and accuracy. In order to realize the high precision grinding of those ductile elements, the low deformation vacuum chuck was designed first, which was used for clamping the optics with high supporting rigidity in the full aperture. Then the optics was planar grinded under vacuum adsorption. After machining, the vacuum system was turned off. The form error of optics was on-machine measured using displacement sensor after elastic restitution. The flatness would be convergenced with high accuracy by compensation machining, whose trajectories were integrated with the measurement result. For purpose of getting high parallelism, the optics was turned over and compensation grinded using the form error of vacuum chuck. Finally, the grinding experiment of large scale and ultra thin fused silica optics with aperture of 430mm×430mm×10mm was performed. The best P-V flatness of optics was below 3 μm, and parallelism was below 3 ″. This machining technique has applied in batch grinding of large scale and ultra thin optics.

  17. Silica artificial opal incorporated with silver nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Li Wenjiang, E-mail: wjli@zju.edu.cn [Center for Optical and Electromagnetic Research, State Key Laboratory for Modern Optical Instrumentation, Zhejiang University, Joint Research Center of Photonics of the Royal Institute of Technology and Zhejiang University, Zijingang Campus, Room 210, East Building 5, Hangzhou 310058 (China); Sun Tan [Center for Optical and Electromagnetic Research, State Key Laboratory for Modern Optical Instrumentation, Zhejiang University, Joint Research Center of Photonics of the Royal Institute of Technology and Zhejiang University, Zijingang Campus, Room 210, East Building 5, Hangzhou 310058 (China)

    2009-07-15

    The silica artificial opal with a three-dimensional (3D) periodic structure was prepared using highly monodispersed silica microspheres by a force packing method in ITO glass cell. The silica artificial opal incorporated with silver nanoparticles was fabricated by the electroplating technique. The optical microscope images of the synthetic sample and the corresponding optical properties were measured after each treatment of electroplating-washing-drying circle. The transmission and reflection spectra presented a red shift, showing that the effective refractive index of the complex silver/silica opal increased after each electroplating. Combining the SEM images, it was seen that the silver nanoparticles could be directly deposited on the surface of silica spheres in the opaline structure. The silver/silica complex opal film could provide a simple way to tune the opal properties by controlling silver nanoparticles in the silica opal. The silver/silica opal crystal structures could be used for nano-photonic circuits, white-light LEDs or as photocatalysts.

  18. Silica artificial opal incorporated with silver nanoparticles

    International Nuclear Information System (INIS)

    Li Wenjiang; Sun Tan

    2009-01-01

    The silica artificial opal with a three-dimensional (3D) periodic structure was prepared using highly monodispersed silica microspheres by a force packing method in ITO glass cell. The silica artificial opal incorporated with silver nanoparticles was fabricated by the electroplating technique. The optical microscope images of the synthetic sample and the corresponding optical properties were measured after each treatment of electroplating-washing-drying circle. The transmission and reflection spectra presented a red shift, showing that the effective refractive index of the complex silver/silica opal increased after each electroplating. Combining the SEM images, it was seen that the silver nanoparticles could be directly deposited on the surface of silica spheres in the opaline structure. The silver/silica complex opal film could provide a simple way to tune the opal properties by controlling silver nanoparticles in the silica opal. The silver/silica opal crystal structures could be used for nano-photonic circuits, white-light LEDs or as photocatalysts.

  19. Silica nanoparticle stability in biological media revisited.

    Science.gov (United States)

    Yang, Seon-Ah; Choi, Sungmoon; Jeon, Seon Mi; Yu, Junhua

    2018-01-09

    The stability of silica nanostructure in the core-silica shell nanomaterials is critical to understanding the activity of these nanomaterials since the exposure of core materials due to the poor stability of silica may cause misinterpretation of experiments, but unfortunately reports on the stability of silica have been inconsistent. Here, we show that luminescent silver nanodots (AgNDs) can be used to monitor the stability of silica nanostructures. Though relatively stable in water and phosphate buffered saline, silica nanoparticles are eroded by biological media, leading to the exposure of AgNDs from AgND@SiO 2 nanoparticles and the quenching of nanodot luminescence. Our results reveal that a synergistic effect of organic compounds, particularly the amino groups, accelerates the erosion. Our work indicates that silica nanostructures are vulnerable to cellular medium and it may be possible to tune the release of drug molecules from silica-based drug delivery vehicles through controlled erosion.

  20. Thermally stable silica-coated hydrophobic gold nanoparticles.

    Science.gov (United States)

    Kanehara, Masayuki; Watanabe, Yuka; Teranishi, Toshiharu

    2009-01-01

    We have successfully developed a method for silica coating on hydrophobic dodecanethiol-protected Au nanoparticles with coating thickness ranging from 10 to 40 nm. The formation of silica-coated Au nanoparticles could be accomplished via the preparation of hydrophilic Au nanoparticle micelles by cationic surfactant encapsulation in aqueous phase, followed by hydrolysis of tetraethylorthosilicate on the hydrophilic surface of gold nanoparticle micelles. Silica-coated Au nanoparticles exhibited quite high thermal stability, that is, no agglomeration of the Au cores could be observed after annealing at 600 degrees C for 30 min. Silica-coated Au nanoparticles could serve as a template to derive hollow nanoparticles. An addition of NaCN solution to silica-coated Au nanoparticles led the formation of hollow silica nanoparticles, which were redispersible in deionized water. The formation of the hollow silica nanoparticles results from the mesoporous structures of the silica shell and such a mesoporous structure is applicable to both catalyst support and drug delivery.

  1. Aperture and optics–measurements and conclusions

    CERN Document Server

    Redaelli, S; Bruce, R; Buffat, X; Giovannozzi, M; Lamont, M; Miyamoto, R; Müller, G; Tomás, R; Vanbavinckhove, G; Wenninger, J

    2012-01-01

    In 2011, the LHC has delivered collisions with different optics configurations in the four interaction points, at an operating energy of 3.5 TeV. The performance has been pushed during the year until a final configuration with 3 IPs squeezed to 1 m was achieved. Correspondingly, the machine aperture has been measured in the different configurations at injection and at top energy, to ensure a safe operation in all conditions of $\\beta^*$ and crossing angle configuration. In this paper, the 2011 commissioning experience of LHC optics is reviewed and the results of aperture measurements are presented. Measurement requirements for 2012 and possible improvements are also discussed.

  2. Enhanced transmission of transverse electric waves through periodic arrays of structured subwavelength apertures

    DEFF Research Database (Denmark)

    Xiao, Sanshui; Peng, Liang; Mortensen, Asger

    2010-01-01

    Transmission through sub-wavelength apertures in perfect metals is expected to be strongly suppressed. However, by structural engineering of the apertures, we numerically demonstrate that the transmission of transverse electric waves through periodic arrays of subwavelength apertures in a thin...... metallic film can be significantly enhanced. Based on equivalent circuit theory analysis, periodic arrays of square structured subwavelength apertures are obtained with a 1900-fold transmission enhancement factor when the side length a of the apertures is 10 times smaller than the wavelength (a/λ =0...

  3. Chitosan-silica complex membranes from sulfonic acid functionalized silica nanoparticles for pervaporation dehydration of ethanol-water solutions.

    Science.gov (United States)

    Liu, Ying-Ling; Hsu, Chih-Yuan; Su, Yu-Huei; Lai, Juin-Yih

    2005-01-01

    Nanosized silica particles with sulfonic acid groups (ST-GPE-S) were utilized as a cross-linker for chitosan to form a chitosan-silica complex membranes, which were applied to pervaporation dehydration of ethanol-water solutions. ST-GPE-S was obtained from reacting nanoscale silica particles with glycidyl phenyl ether, and subsequent sulfonation onto the attached phenyl groups. The chemical structure of the functionalized silica was characterized with FTIR, (1)H NMR, and energy-dispersive X-ray. Homogeneous dispersion of the silica particles in chitosan was observed with electronic microscopies, and the membranes obtained were considered as nanocomposites. The silica nanoparticles in the membranes served as spacers for polymer chains to provide extra space for water permeation, so as to bring high permeation rates to the complex membranes. With addition of 5 parts per hundred of functionalized silica into chitosan, the resulting membrane exhibited a separation factor of 919 and permeation flux of 410 g/(m(2) h) in pervaporation dehydration of 90 wt % ethanol aqueous solution at 70 degrees C.

  4. Finite element analysis of stresses in Berkovich, Vickers and Knoop indentation for densifying and non-densifying glasses

    Science.gov (United States)

    Chen, Kanghua

    2002-08-01

    A constitutive law for fused silica accounting for its permanent densification under large compressive stresses is presented. The implementation of the constitutive equations in the general-purpose finite element code ABAQUS via user subroutine is proposed and carefully verified. The three-dimensional indentation mechanics under Berkovich, Vickers and Knoop indenters is extensively investigated based on the proposed constitutive relation. The results of stress distribution and plastic zone for both densifying and non-densifying optical glasses are systematically compared. These numerical results are in good agreement with the experimental observations of optical manufacturing. That is, fused silica shows lower material removal rate, smaller surface roughness and subsurface damage in contrast to non-densifying optical glasses under the same grinding condition. Material densification of fused silica is thoroughly studied through numerical simulations of indentation mechanics. The exact amount of densification and shear strain of fused silica under Berkovich indentation is calculated to show the deformation mechanism of glass materials under three-dimensional indentations. The surface profiles show the material "pile-up" around the indenter tip for non-densifying glasses and "sink-in" for fused silica after the indentation load is removed. An important inverse problem is studied: estimation of abrasive size and indentation load through the examination of residual indentation footprints. A series of 2D axisymmetric spherical indentation simulations generate a wide range of relationships among the indentation load, indenter size, residual indentation depth and size of residual indentation zone for the five selected brittle materials: glass fused silica (FS), BK7, semiconductor Si, laser glass LHG8, and optical crystal CaF2.. The application of the inverse problem is verified by the good agreement between the estimated abrasive size and the actual abrasive size found

  5. Design and fabrication of a polarization-independent two-port beam splitter.

    Science.gov (United States)

    Feng, Jijun; Zhou, Changhe; Zheng, Jiangjun; Cao, Hongchao; Lv, Peng

    2009-10-10

    We design and manufacture a fused-silica polarization-independent two-port beam splitter grating. The physical mechanism of this deeply etched grating can be shown clearly by using the simplified modal method with consideration of corresponding accumulated phase difference of two excited propagating grating modes, which illustrates that the binary-phase fused-silica grating structure depends little on the incident wavelength, but mainly on the ratio of groove depth to grating period and the ratio of incident wavelength to grating period. These analytic results would also be very helpful for wavelength bandwidth analysis. The exact grating profile is optimized by using the rigorous coupled-wave analysis. Holographic recording technology and inductively coupled plasma etching are used to manufacture the fused-silica grating. Experimental results agree well with the theoretical values.

  6. Fast decoding algorithms for coded aperture systems

    International Nuclear Information System (INIS)

    Byard, Kevin

    2014-01-01

    Fast decoding algorithms are described for a number of established coded aperture systems. The fast decoding algorithms for all these systems offer significant reductions in the number of calculations required when reconstructing images formed by a coded aperture system and hence require less computation time to produce the images. The algorithms may therefore be of use in applications that require fast image reconstruction, such as near real-time nuclear medicine and location of hazardous radioactive spillage. Experimental tests confirm the efficacy of the fast decoding techniques

  7. Amorphous silica from rice husk at various temperatures

    International Nuclear Information System (INIS)

    Javed, S.J.; Feroze, N.; Tajwar, S.

    2008-01-01

    Rice husk is being used as a source of energy in many heat generating system because of its high calorific value and its availability in many rice producing areas. Rice husk contains approximately 20% silica which is presented in hydrated form. This hydrated silica can be retrieved as amorphous silica under controlled thermal conditions. Uncontrolled burning of rice husk produces crystalline silica which is not reactive silica but can be used as filler in many applications. Amorphous silica is reactive silica which has better market value due to its reactive nature in process industry. The present study deals with the production of amorphous silica at various temperatures from rice husk. Various ashes were prepared in tube furnace by changing the burning temperatures for fixed time intervals and analyzed by XRD. It has been observed that for two hours calculation's of rice husk renders mostly amorphous silica at 650 degree C where as at higher temperatures crystalline silica was obtained. (author)

  8. Cellular membrane trafficking of mesoporous silica nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Fang, I-Ju [Iowa State Univ., Ames, IA (United States)

    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

  9. Synthesis of Various Silica Nanoparticles for Foam Stability

    International Nuclear Information System (INIS)

    Yoon, Suk Bon; Yoon, Inho; Jung, Chonghun; Kim, Chorong; Choi, Wangkyu; Moon, Jeikwon

    2013-01-01

    The synthesis of the non-porous silica nanoparticles with uniform sizes has been reported through the Sto ber method, the synthesis of meso porous silica nanoparticles with a specific morphology such as core-shell, rod-like, and hexagonal shapes is not so common. As a synthetic strategy for controlling the particle size, shape, and porosity, the synthesis of core-shell silicas with meso porous shells formed on silica particle cores through the self-assembly of silica precursor and organic templates or spherical meso porous silicas using modified Sto ber method was also reported. Recently, in an effort to reduce the amount of radioactive waste and enhance the decontamination efficiency during the decontamination process of nuclear facilities contaminated with radionuclides, a few research for the preparation of the decontamination foam containing solid nanoparticles has been reported. In this work, the silica nanoparticles with various sizes, shapes, and structures were synthesized based on the previous literatures. The resulting silica nanoparticles were used to investigate the effect of the nanoparticles on the foam stability. In a study on the foam stability using various silica nanoparticles, the results showed that the foam volume and liquid volume in foam was enhanced when using a smaller size and lower density of the silica nanoparticles. Silica nanoparticles with various sizes, shapes, and structures such as a non-porous, meso porous core-shell, and meso porous silica were synthesized to investigate the effect of the foam stability. The sizes and structural properties of the silica nanoparticles were easily controlled by varying the amount of silica precursor, surfactant, and ammonia solution as a basic catalyst. The foam prepared using various silica nanoparticles showed that foam the volume and liquid volume in the foam were enhanced when using a smaller size and lower density of the silica nanoparticles

  10. Silica removal in industrial effluents with high silica content and low hardness.

    Science.gov (United States)

    Latour, Isabel; Miranda, Ruben; Blanco, Angeles

    2014-01-01

    High silica content of de-inked paper mill effluents is limiting their regeneration and reuse after membrane treatments such as reverse osmosis (RO). Silica removal during softening processes is a common treatment; however, the effluent from the paper mill studied has a low hardness content, which makes the addition of magnesium compounds necessary to increase silica removal. Two soluble magnesium compounds (MgCl₂∙6H₂O and MgSO₄∙7H₂O) were tested at five dosages (250-1,500 mg/L) and different initial pH values. High removal rates (80-90%) were obtained with both products at the highest pH tested (11.5). With these removal efficiencies, it is possible to work at high RO recoveries (75-85%) without silica scaling. Although pH regulation significantly increased the conductivity of the waters (at pH 11.5 from 2.1 to 3.7-4.0 mS/cm), this could be partially solved by using Ca(OH)₂ instead of NaOH as pH regulator (final conductivity around 3.0 mS/cm). Maximum chemical oxygen demand (COD) removal obtained with caustic soda was lower than with lime (15 vs. 30%). Additionally, the combined use of a polyaluminum coagulant during the softening process was studied; the coagulant, however, did not significantly improve silica removal, obtaining a maximum increase of only 10%.

  11. Scale-dependent Patterns in One-dimensional Fracture Spacing and Aperture Data

    Science.gov (United States)

    Roy, A.; Perfect, E.

    2013-12-01

    One-dimensional scanline data about fracture spacing and size attributes such as aperture or length are mostly considered in separate studies that compute the cumulative frequency of these attributes without regard to their actual spatial sequence. In a previous study, we showed that spacing data can be analyzed using lacunarity to identify whether fractures occur in clusters. However, to determine if such clusters also contain the largest fractures in terms of a size attribute such as aperture, it is imperative that data about the size attribute be integrated with information about fracture spacing. While for example, some researchers have considered aperture in conjunction with spacing, their analyses were either applicable only to a specific type of data (e.g. multifractal) or failed to characterize the data at different scales. Lacunarity is a technique for analyzing multi-scale non-binary data and is ideally-suited for characterizing scanline data with spacing and aperture values. We present a technique that can statistically delineate the relationship between size attributes and spatial clustering. We begin by building a model scanline that has complete partitioning of fractures with small and large apertures between the intercluster regions and clusters. We demonstrate that the ratio of lacunarity for this model to that of its counterpart for a completely randomized sequence of apertures can be used to determine whether large-aperture fractures preferentially occur next to each other. The technique is then applied to two natural fracture scanline datasets, one with most of the large apertures occurring in fracture clusters, and the other with more randomly-spaced fractures, without any specific ordering of aperture values. The lacunarity ratio clearly discriminates between these two datasets and, in the case of the first example, it is also able to identify the range of scales over which the widest fractures are clustered. The technique thus developed for

  12. Dynamic aperture and transverse proton diffusion in HERA

    International Nuclear Information System (INIS)

    Zimmermann, F.

    1994-04-01

    The dynamic aperture caused by persistent-current nonlinear field errors is an important concern in the design of superconducting hadron storage rings. The HERA proton ring is the second superconducting accelerator in operation. In this lecture note, its measured dynamic aperture is compared with that inferred from comprehensive trackig studies. To understand the difference between prediction and measurement, a semi-analytical method is developed for evaluating transverse diffusion rates due to various processes, such as modulational diffusion or sweeping diffusion this analysis makes use of parameters for high-order resonances in the transverse phase space, which are obtained by normal-form algorithms using differential-algebra software. This semi-analytical results are consistent wit the measurements, and suggest that the actual dynamic aperture is caused by an interplay of tune modulation and nonlinear magnetic fields

  13. Spaceborne L-band Radiometers: Push-broom or Synthetic Aperture?

    DEFF Research Database (Denmark)

    Skou, Niels

    2004-01-01

    L-band radiometers can measure ocean salinity and soil moisture from space. A synthetic aperture radiometer system, SMOS, is under development by ESA for launch in 2007. A real aperture push-broom system, Aquarius, has been approved by NASA for launch in 2008. Pros et cons of the two fundamentally...

  14. Fundamental study of FC-72 pool boiling surface temperature fluctuations and bubble behavior

    Science.gov (United States)

    Griffin, Alison R.

    A heater designed to monitor surface temperature fluctuations during pool boiling experiments while the bubbles were simultaneously being observed has been fabricated and tested. The heat source was a transparent indium tin oxide (ITO) layer commercially deposited on a fused quartz substrate. Four copper-nickel thin film thermocouples (TFTCs) on the heater surface measured the surface temperature, while a thin layer of sapphire or fused silica provided electrical insulation between the TFTCs and the ITO. The TFTCs were micro-fabricated using the liftoff process to deposit the nickel and copper metal films. The TFTC elements were 50 mum wide and overlapped to form a 25 mum by 25 mum junction. TFTC voltages were recorded by a DAQ at a sampling rate of 50 kHz. A high-speed CCD camera recorded bubble images from below the heater at 2000 frames/second. A trigger sent to the camera by the DAQ synchronized the bubble images and the surface temperature data. As the bubbles and their contact rings grew over the TFTC junction, correlations between bubble behavior and surface temperature changes were demonstrated. On the heaters with fused silica insulation layers, 1--2°C temperature drops on the order of 1 ms occurred as the contact ring moved over the TFTC junction during bubble growth and as the contact ring moved back over the TFTC junction during bubble departure. These temperature drops during bubble growth and departure were due to microlayer evaporation and liquid rewetting the heated surface, respectively. Microlayer evaporation was not distinguished as the primary method of heat removal from the surface. Heaters with sapphire insulation layers did not display the measurable temperature drops observed with the fused silica heaters. The large thermal diffusivity of the sapphire compared to the fused silica was determined as the reason for the absence of these temperature drops. These findings were confirmed by a comparison of temperature drops in a 2-D simulation of

  15. DESIGN OF MULTILAYER APERTURE COUPLED STACKED MICROSTRIP PATCH ANTENNA FOR WLAN APPLICATIONS

    Directory of Open Access Journals (Sweden)

    P. Jothilakshmi

    2015-10-01

    Full Text Available One of the major drawbacks of microstrip patch antenna is its narrow bandwidth. The solution of this problem is to use aperture coupled stacked micro strip patch antenna. The antenna uses a combination of aperture coupled feeding technique and multi- layer radiating patch in order for the radiating elements are increase the gain bandwidth. The ‘I’ and ‘H’ shaped aperture slots are etched onto the ground plane. It is used to transfer the energy from feed line to stacked patch. A variation of the feed line length controls the selected aperture slots to be active. The waves from the selected activated aperture slots will radiate to particular radiating patch and achieve the desired resonant frequency. The air gap is used to avoid coupling loss between the aperture slots and stacked patches. The observed simulated and measured results show that the proposed antenna structure resonated at 2.51 GHz frequency with reduced return loss and optimum voltage standing wave ratio.

  16. MD1405: Demonstration of forced dynamic aperture measurements at injection

    CERN Document Server

    Carlier, Felix Simon; Persson, Tobias Hakan Bjorn; Tomas Garcia, Rogelio; CERN. Geneva. ATS Department

    2017-01-01

    Accurate measurements of dynamic aperture become more important for the LHC as it advances into increasingly nonlinear regimes of operations, as well as for the High Luminosity LHC where machine nonlinearities will have a significantly larger impact. Direct dynamic aperture measurements at top energy in the LHC are challenging, and conventional single kick methods are not viable. Dynamic aperture measurements under forced oscillation of AC dipoles have been proposed as s possible alternative observable. A first demonstration of forced DA measurements at injections energy is presented.

  17. Apodised aperture using rotation of plane of polarization

    International Nuclear Information System (INIS)

    Simmons, W.W.; Leppelmeier, G.W.; Johnson, B.C.

    1975-01-01

    An apodised aperture based on the rotation of plane of polarization producing desirable characteristics on a transmitted light beam such as beam profiling in high flux laser amplifier chains is described. The apodised aperture is made with a lossless element by using one or more polarizers and/or analyzers and magneto-optical Faraday means for selectively rotating the plane of polarized radiation over the cross section to effect the desired apodisation

  18. 11 T Twin-Aperture Nb$_3$Sn Dipole Development for LHC Upgrades

    CERN Document Server

    Zlobin, A V; Apollinari, G; Auchmann, B; Barzi, E; Izquierdo Bermudez, S; Bossert, R; Buehler, M; Chlachidze, G; DiMarco, J; Karppinen, M; Nobrega, F; Novitski, I; Rossi, L; Smekens, D; Tartaglia, M; Turrioni, D; Velev, Genadi

    2015-01-01

    FNAL and CERN are developing a twin-aperture 11 T Nb$_{3}$Sn dipole suitable for installation in the LHC. This paper describes the design and parameters of the 11 T dipole developed at FNAL for the LHC upgrades in both single-aperture and twin-aperture configurations, and presents details of the constructed dipole models. Results of studies of magnet quench performance, quench protection and magnetic measurements performed using short 1 m long coils in the dipole mirror and single-aperture configurations are reported and discussed.

  19. 11 T Twin-Aperture Nb$_3$Sn Dipole Development for LHC Upgrades

    Energy Technology Data Exchange (ETDEWEB)

    Zlobin, A. V. [Fermilab; Andreev, N. [Fermilab; Apollinari, G. [Fermilab; Auchmann, B. [CERN; Barzi, E. [Fermilab; Izquierdo Bermudez, S. [CERN; Bossert, R. [Fermilab; Buehler, M. [Fermilab; Chlachidze, G. [Fermilab; DiMarco, J. [Fermilab; Karppinen, M. [CERN; Nobrega, F. [Fermilab; Novitski, I. [CERN; Rossi, L. [CERN; Smekens, D. [CERN; Tartaglia, M. [Fermilab; Turrioni, D. [Fermilab; Velev, Genadi [Fermilab

    2015-01-01

    FNAL and CERN are developing a twin-aperture 11 T Nb3Sn dipole suitable for installation in the LHC. This paper describes the design and parameters of the 11 T dipole developed at FNAL for the LHC upgrades in both single-aperture and twin-aperture configurations, and presents details of the constructed dipole models. Results of studies of magnet quench performance, quench protection and magnetic measurements performed using short 1 m long coils in the dipole mirror and single-aperture configurations are reported and discussed.

  20. A functional probe with bowtie aperture and bull's eye structure for nanolithograph

    International Nuclear Information System (INIS)

    Wang Shuo; Wang Qiao; Guo Ying-Yan; Pan Shi; Li Xu-Feng

    2012-01-01

    The bowtie aperture surrounded by concentric gratings (the bull's eye structure) integrated on the near-field scanning optical microscopy (NSOM) probe (aluminum coated fiber tip) for nanolithography has been investigated using the finite-difference time domain (FDTD) method. By modifying the parameters of the bowtie aperture and the concentric gratings, a maximal field enhancement factor of 391.69 has been achieved, which is 18 times larger than that obtained from the single bowtie aperture. Additionally, the light spot depends on the gap size of the bowtie aperture and can be confined to sub-wavelength. The superiority of the combination of the bowtie aperture and the bull's eye structure is confirmed, and the mechanism for the electric field enhancement in this derived structure is analyzed

  1. A functional probe with bowtie aperture and bull's eye structure for nanolithograph

    Science.gov (United States)

    Wang, Shuo; Li, Xu-Feng; Wang, Qiao; Guo, Ying-Yan; Pan, Shi

    2012-10-01

    The bowtie aperture surrounded by concentric gratings (the bull's eye structure) integrated on the near-field scanning optical microscopy (NSOM) probe (aluminum coated fiber tip) for nanolithography has been investigated using the finite-difference time domain (FDTD) method. By modifying the parameters of the bowtie aperture and the concentric gratings, a maximal field enhancement factor of 391.69 has been achieved, which is 18 times larger than that obtained from the single bowtie aperture. Additionally, the light spot depends on the gap size of the bowtie aperture and can be confined to sub-wavelength. The superiority of the combination of the bowtie aperture and the bull's eye structure is confirmed, and the mechanism for the electric field enhancement in this derived structure is analyzed.

  2. Tibial valgus aperture osteotomy

    International Nuclear Information System (INIS)

    De los Rios G, Adolfo Leon; Saavedra Abadia, Adolfo Leon; Palacios, Julio

    2005-01-01

    This study is based on work carried out a The knee clinic at the arthroscopic surgery unit of the Institute of osteo-articular diseases, Imbanaco Medical Centre, The University Hospital of the Valle (Cali-Colombia) and The Fractures Clinic Ltd. (Palmira-Valle). This is a descriptive study, which demonstrates very positive outcomes for aperture osteotomy, without detracting from the importance of, and the progress made in uni-compartmental and total joint articular replacements of the knee. 10 patients were treated with a highs tibial open osteotomy between November 1988 and December 2002: 3 had post-traumatic deformities, without arthrosic alterations; 1 had pseudo-arthrosis caused by a failed corrective procedure; 1 had complex instability of the knee with osseous varus; 6 had a degenerative lesion of the medial meniscus with medial condral alterations. Follow-up was form 12 to 54 months. Treatment involved a tibial valgus aperture osteotomy and osteo-synthesis. Evaluation was carried out using the International Knee Documentation Committee (IKDC) scale, the For Special Surgery and The Knee Society Score

  3. Endodontic therapy for a fused mandibular molar.

    Science.gov (United States)

    Rotstein, I; Moshonov, J; Cohenca, N

    1997-06-01

    Variations in tooth morphology present a clinical challenge when endodontic treatment is required. A case of conservative endodontic therapy for a fused mandibular second and third molar is presented.

  4. FFT-enhanced IHS transform method for fusing high-resolution satellite images

    Science.gov (United States)

    Ling, Y.; Ehlers, M.; Usery, E.L.; Madden, M.

    2007-01-01

    Existing image fusion techniques such as the intensity-hue-saturation (IHS) transform and principal components analysis (PCA) methods may not be optimal for fusing the new generation commercial high-resolution satellite images such as Ikonos and QuickBird. One problem is color distortion in the fused image, which causes visual changes as well as spectral differences between the original and fused images. In this paper, a fast Fourier transform (FFT)-enhanced IHS method is developed for fusing new generation high-resolution satellite images. This method combines a standard IHS transform with FFT filtering of both the panchromatic image and the intensity component of the original multispectral image. Ikonos and QuickBird data are used to assess the FFT-enhanced IHS transform method. Experimental results indicate that the FFT-enhanced IHS transform method may improve upon the standard IHS transform and the PCA methods in preserving spectral and spatial information. ?? 2006 International Society for Photogrammetry and Remote Sensing, Inc. (ISPRS).

  5. The Pozzolanic reaction of silica fume

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede

    2012-01-01

    Silica fume is a very important supplementary cementitious binder in High-Performance and Ultra High-Performance Concretes. Through its pozzolanic reaction the silica fume densifies the concrete micro-structure, in particular it strengthens the paste-aggregate interfacial transition zone. In the ......Silica fume is a very important supplementary cementitious binder in High-Performance and Ultra High-Performance Concretes. Through its pozzolanic reaction the silica fume densifies the concrete micro-structure, in particular it strengthens the paste-aggregate interfacial transition zone....... In the present paper different aspects of the pozzolanic reaction of silica fume are investigated. These include chemical shrinkage, isothermal heat development and strength development. Key data for these are given and compared with theoretical calculations, and based on presented measurements the energy...

  6. Application of Ruze Equation for Inflatable Aperture Antennas

    Science.gov (United States)

    Welch, Bryan W.

    2008-01-01

    Inflatable aperture reflector antennas are an emerging technology that NASA is investigating for potential uses in science and exploration missions. As inflatable aperture antennas have not been proven fully qualified for space missions, they must be characterized properly so that the behavior of the antennas can be known in advance. To properly characterize the inflatable aperture antenna, testing must be performed in a relevant environment, such as a vacuum chamber. Since the capability of having a radiofrequency (RF) test facility inside a vacuum chamber did not exist at NASA Glenn Research Center, a different methodology had to be utilized. The proposal to test an inflatable aperture antenna in a vacuum chamber entailed performing a photogrammetry study of the antenna surface by using laser ranging measurements. A root-mean-square (rms) error term was derived from the photogrammetry study to calculate the antenna surface loss as described by the Ruze equation. However, initial testing showed that problems existed in using the Ruze equation to calculate the loss due to errors on the antenna surface. This study utilized RF measurements obtained in a near-field antenna range and photogrammetry data taken from a laser range scanner to compare the expected performance of the test antenna (via the Ruze equation) with the actual RF patterns and directivity measurements. Results showed that the Ruze equation overstated the degradation in the directivity calculation. Therefore, when the photogrammetry study is performed on the test antennas in the vacuum chamber, a more complex equation must be used in light of the fact that the Ruze theory overstates the loss in directivity for inflatable aperture reflector antennas.

  7. Dynamic Aperture Studies for SPEAR 3

    International Nuclear Information System (INIS)

    Corbett, William

    1998-01-01

    The Stanford Synchrotron Radiation Laboratory is investigating an accelerator upgrade project that would replace the present 130 nm rad FODO lattice with an 18 nm rad double bend achromat (DBA) lattice: SPEAR 3. The low emittance design yields a high brightness beam, but the stronger focusing in the DBA lattice increases chromaticity and beam sensitivity to machine errors. To ensure efficient injection and long Touschek lifetime, an optimization of the design lattice and dynamic aperture has been performed. In this paper, we review the methods used to maximize the SPEAR 3 dynamic aperture including necessary optics modifications, choice of tune and phase advance, optimization of sextupole and coupling correction, and modeling effects of machine errors, wigglers and lattice periodicity

  8. Simulation of an aperture-based antihydrogen gravity experiment

    Directory of Open Access Journals (Sweden)

    C. A. Ordonez

    2012-03-01

    Full Text Available A Monte Carlo simulation is presented of an experiment that could potentially determine whether antihydrogen accelerates vertically up or down as a result of earth's gravity. The experiment would rely on methods developed by existing antihydrogen research collaborations and would employ a Penning trap for the production of antihydrogen within a uniform magnetic field. The axis of symmetry of the cylindrical trap wall would be oriented horizontally, and an axisymmetric aperture (with an inner radius that is smaller than the cylindrical trap wall radius would be present a short distance away from the antihydrogen production region. Antihydrogen annihilations that occur along the cylindrical trap wall would be detected by the experiment. The distribution of annihilations along the wall would vary near the aperture, because some antihydrogen that would otherwise annihilate at the wall would instead annihilate on the aperture. That is, a shadow region forms behind the aperture, and the distribution of annihilations near the boundary of the shadow region is not azimuthally symmetric when the effect of gravity is significant. The Monte Carlo simulation is used together with analytical modeling to determine conditions under which the annihilation distribution would indicate the direction of the acceleration of antihydrogen due to gravity.

  9. Development of procedures for programmable proximity aperture lithography

    Energy Technology Data Exchange (ETDEWEB)

    Whitlow, H.J., E-mail: harry.whitlow@he-arc.ch [Institut des Microtechnologies Appliquées Arc, Haute Ecole Arc Ingénierie, Eplatures-Grise 17, CH-2300 La Chaux-de-Fonds (Switzerland); Department of Physics, University of Jyväskylä, P.O. Box 35 (YFL), FI-40014 Jyväskylä (Finland); Gorelick, S. [VTT Technical Research Centre of Finland, P.O. Box 1000, Tietotie 3, Espoo, FI-02044 VTT (Finland); Puttaraksa, N. [Department of Physics, University of Jyväskylä, P.O. Box 35 (YFL), FI-40014 Jyväskylä (Finland); Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Napari, M.; Hokkanen, M.J.; Norarat, R. [Department of Physics, University of Jyväskylä, P.O. Box 35 (YFL), FI-40014 Jyväskylä (Finland)

    2013-07-01

    Programmable proximity aperture lithography (PPAL) with MeV ions has been used in Jyväskylä and Chiang Mai universities for a number of years. Here we describe a number of innovations and procedures that have been incorporated into the LabView-based software. The basic operation involves the coordination of the beam blanker and five motor-actuated translators with high accuracy, close to the minimum step size with proper anti-collision algorithms. By using special approaches, such writing calibration patterns, linearisation of position and careful backlash correction the absolute accuracy of the aperture size and position, can be improved beyond the standard afforded by the repeatability of the translator end-point switches. Another area of consideration has been the fluence control procedures. These involve control of the uniformity of the beam where different approaches for fluence measurement such as simultaneous aperture current and the ion current passing through the aperture using a Faraday cup are used. Microfluidic patterns may contain many elements that make-up mixing sections, reaction chambers, separation columns and fluid reservoirs. To facilitate conception and planning we have implemented a .svg file interpreter, that allows the use of scalable vector graphics files produced by standard drawing software for generation of patterns made up of rectangular elements.

  10. Control of aperture closure during reach-to-grasp movements in Parkinson's disease.

    Science.gov (United States)

    Rand, M K; Smiley-Oyen, A L; Shimansky, Y P; Bloedel, J R; Stelmach, G E

    2006-01-01

    This study examined whether the pattern of coordination between arm-reaching toward an object (hand transport) and the initiation of aperture closure for grasping is different between PD patients and healthy individuals, and whether that pattern is affected by the necessity to quickly adjust the reach-to-grasp movement in response to an unexpected shift of target location. Subjects reached for and grasped a vertical dowel, the location of which was indicated by illuminating one of the three dowels placed on a horizontal plane. In control conditions, target location was fixed during the trial. In perturbation conditions, target location was shifted instantaneously by switching the illumination to a different dowel during the reach. The hand distance from the target at which the subject initiated aperture closure (aperture closure distance) was similar for both the control and perturbation conditions within each group of subjects. However, that distance was significantly closer to the target in the PD group than in the control group. The timing of aperture closure initiation varied considerably across the trials in both groups of subjects. In contrast, aperture closure distance was relatively invariant, suggesting that aperture closure initiation was determined by spatial parameters of arm kinematics rather than temporal parameters. The linear regression analysis of aperture closure distance showed that the distance was highly predictable based on the following three parameters: the amplitude of maximum grip aperture, hand velocity, and hand acceleration. This result implies that a control law, the arguments of which include the above parameters, governs the initiation of aperture closure. Further analysis revealed that the control law was very similar between the subject groups under each condition as well as between the control and perturbation conditions for each group. Consequently, the shorter aperture closure distance observed in PD patients apparently is a

  11. 21 CFR 584.700 - Hydrophobic silicas.

    Science.gov (United States)

    2010-04-01

    ...) Product. Amorphous fumed hydrophobic silica or precipitated hydrophobic silica (CAS Reg. No. 68611-0944... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Hydrophobic silicas. 584.700 Section 584.700 Food... DRUGS, FEEDS, AND RELATED PRODUCTS FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE IN FEED AND...

  12. Biomimetic silica encapsultation of living cells

    Science.gov (United States)

    Jaroch, David Benjamin

    Living cells perform complex chemical processes on size and time scales that artificial systems cannot match. Cells respond dynamically to their environment, acting as biological sensors, factories, and drug delivery devices. To facilitate the use of living systems in engineered constructs, we have developed several new approaches to create stable protective microenvironments by forming bioinspired cell-membrane-specific silica-based encapsulants. These include vapor phase deposition of silica gels, use of endogenous membrane proteins and polysaccharides as a site for silica nucleation and polycondensation in a saturated environment, and protein templated ordered silica shell formation. We demonstrate silica layer formation at the surface of pluripotent stem-like cells, bacterial biofilms, and primary murine and human pancreatic islets. Materials are characterized by AFM, SEM and EDS. Viability assays confirm cell survival, and metabolite flux measurements demonstrate normal function and no major diffusion limitations. Real time PCR mRNA analysis indicates encapsulated islets express normal levels of genetic markers for β-cells and insulin production. The silica glass encapsulant produces a secondary bone like calcium phosphate mineral layer upon exposure to media. Such bioactive materials can improve device integration with surrounding tissue upon implantation. Given the favorable insulin response, bioactivity, and long-term viability observed in silica-coated islets, we are currently testing the encapsulant's ability to prevent immune system recognition of foreign transplants for the treatment of diabetes. Such hybrid silica-cellular constructs have a wide range of industrial, environmental, and medical applications.

  13. Central obscuration effects on optical synthetic aperture imaging

    Science.gov (United States)

    Wang, Xue-wen; Luo, Xiao; Zheng, Li-gong; Zhang, Xue-jun

    2014-02-01

    Due to the central obscuration problem exists in most optical synthetic aperture systems, it is necessary to analyze its effects on their image performance. Based on the incoherent diffraction limited imaging theory, a Golay-3 type synthetic aperture system was used to study the central obscuration effects on the point spread function (PSF) and the modulation transfer function (MTF). It was found that the central obscuration does not affect the width of the central peak of the PSF and the cutoff spatial frequency of the MTF, but attenuate the first sidelobe of the PSF and the midfrequency of the MTF. The imaging simulation of a Golay-3 type synthetic aperture system with central obscuration proved this conclusion. At last, a Wiener Filter restoration algorithm was used to restore the image of this system, the images were obviously better.

  14. Synthetic aperture integration (SAI) algorithm for SAR imaging

    Science.gov (United States)

    Chambers, David H; Mast, Jeffrey E; Paglieroni, David W; Beer, N. Reginald

    2013-07-09

    A method and system for detecting the presence of subsurface objects within a medium is provided. In some embodiments, the imaging and detection system operates in a multistatic mode to collect radar return signals generated by an array of transceiver antenna pairs that is positioned across the surface and that travels down the surface. The imaging and detection system pre-processes the return signal to suppress certain undesirable effects. The imaging and detection system then generates synthetic aperture radar images from real aperture radar images generated from the pre-processed return signal. The imaging and detection system then post-processes the synthetic aperture radar images to improve detection of subsurface objects. The imaging and detection system identifies peaks in the energy levels of the post-processed image frame, which indicates the presence of a subsurface object.

  15. Plasmonic nanofocusing with a metallic pyramid and an integrated C-shaped aperture

    Science.gov (United States)

    Lindquist, Nathan C.; Johnson, Timothy W.; Nagpal, Prashant; Norris, David J.; Oh, Sang-Hyun

    2013-05-01

    We demonstrate the design, fabrication and characterization of a near-field plasmonic nanofocusing probe with a hybrid tip-plus-aperture design. By combining template stripping with focused ion beam lithography, a variety of aperture-based near-field probes can be fabricated with high optical performance. In particular, the combination of large transmission through a C-shaped aperture aligned to the sharp apex (<10 nm radius) of a template-stripped metallic pyramid allows the efficient delivery of light--via the C-shaped aperture--while providing a nanometric hotspot determined by the sharpness of the tip itself.

  16. Large aperture components for solid state laser fusion systems

    International Nuclear Information System (INIS)

    Simmons, W.W.

    1978-01-01

    Solid state lasers for fusion experiments must reliably deliver maximum power to small (approximately .5 mm) targets from stand-off focal distances of 1 m or more. This requirement places stringent limits upon the optical quality, resistance to damage, and overall performance of the several major components--amplifiers, Faraday isolators, spatial filters--in each amplifier train. Component development centers about achieving (1) highest functional material figure of merit, (2) best optical quality, and (3) maximum resistance to optical damage. Specific examples of the performance of large aperture components will be presented within the context of the Argus and Shiva laser systems, which are presently operational at Lawrence Livermore Laboratory. Shiva comprises twenty amplifiers, each of 20 cm output clear aperture. Terawatt beams from these amplifiers are focused through two opposed, nested clusters of f/6 lenses onto such targets. Design requirements upon the larger aperture Nova laser components, up to 35 cm in clear aperture, will also be discussed; these pose a significant challenge to the optical industry

  17. Colored fused filament fabrication

    OpenAIRE

    Song, Haichuan; Lefebvre, Sylvain

    2017-01-01

    Filament fused fabrication is the method of choice for printing 3D models at low cost, and is the de-facto standard for hobbyists, makers and schools. Unfortunately, filament printers cannot truly reproduce colored objects. The best current techniques rely on a form of dithering exploiting occlusion, that was only demonstrated for shades of two base colors and that behaves differently depending on surface slope. We explore a novel approach for 3D printing colored objects, capable of creating ...

  18. A new parameter-free soft-core potential for silica and its application to simulation of silica anomalies

    Energy Technology Data Exchange (ETDEWEB)

    Izvekov, Sergei, E-mail: sergiy.izvyekov.civ@mail.mil; Rice, Betsy M. [Weapons and Materials Research Directorate, U.S. Army Research Laboratory, Aberdeen Proving Ground, Maryland 21005 (United States)

    2015-12-28

    A core-softening of the effective interaction between oxygen atoms in water and silica systems and its role in developing anomalous thermodynamic, transport, and structural properties have been extensively debated. For silica, the progress with addressing these issues has been hampered by a lack of effective interaction models with explicit core-softening. In this work, we present an extension of a two-body soft-core interatomic force field for silica recently reported by us [S. Izvekov and B. M. Rice, J. Chem. Phys. 136(13), 134508 (2012)] to include three-body forces. Similar to two-body interaction terms, the three-body terms are derived using parameter-free force-matching of the interactions from ab initio MD simulations of liquid silica. The derived shape of the O–Si–O three-body potential term affirms the existence of repulsion softening between oxygen atoms at short separations. The new model shows a good performance in simulating liquid, amorphous, and crystalline silica. By comparing the soft-core model and a similar model with the soft-core suppressed, we demonstrate that the topology reorganization within the local tetrahedral network and the O–O core-softening are two competitive mechanisms responsible for anomalous thermodynamic and kinetic behaviors observed in liquid and amorphous silica. The studied anomalies include the temperature of density maximum locus and anomalous diffusivity in liquid silica, and irreversible densification of amorphous silica. We show that the O–O core-softened interaction enhances the observed anomalies primarily through two mechanisms: facilitating the defect driven structural rearrangements of the silica tetrahedral network and modifying the tetrahedral ordering induced interactions toward multiple characteristic scales, the feature which underlies the thermodynamic anomalies.

  19. Terahertz near-field imaging using subwavelength plasmonic apertures and a quantum cascade laser source.

    Science.gov (United States)

    Baragwanath, Adam J; Freeman, Joshua R; Gallant, Andrew J; Zeitler, J Axel; Beere, Harvey E; Ritchie, David A; Chamberlain, J Martyn

    2011-07-01

    The first demonstration, to our knowledge, of near-field imaging using subwavelength plasmonic apertures with a terahertz quantum cascade laser source is presented. "Bull's-eye" apertures, featuring subwavelength circular apertures flanked by periodic annular corrugations were created using a novel fabrication method. A fivefold increase in intensity was observed for plasmonic apertures over plain apertures of the same diameter. Detailed studies of the transmitted beam profiles were undertaken for apertures with both planarized and corrugated exit facets, with the former producing spatially uniform intensity profiles and subwavelength spatial resolution. Finally, a proof-of-concept imaging experiment is presented, where an inhomogeneous pharmaceutical drug coating is investigated.

  20. Particle-in-Cell Modeling of Magnetized Argon Plasma Flow Through Small Mechanical Apertures

    Energy Technology Data Exchange (ETDEWEB)

    Adam B. Sefkow and Samuel A. Cohen

    2009-04-09

    Motivated by observations of supersonic argon-ion flow generated by linear helicon-heated plasma devices, a three-dimensional particle-in-cell (PIC) code is used to study whether stationary electrostatic layers form near mechanical apertures intersecting the flow of magnetized plasma. By self-consistently evaluating the temporal evolution of the plasma in the vicinity of the aperture, the PIC simulations characterize the roles of the imposed aperture and applied magnetic field on ion acceleration. The PIC model includes ionization of a background neutral-argon population by thermal and superthermal electrons, the latter found upstream of the aperture. Near the aperture, a transition from a collisional to a collisionless regime occurs. Perturbations of density and potential, with mm wavelengths and consistent with ion acoustic waves, propagate axially. An ion acceleration region of length ~ 200-300 λD,e forms at the location of the aperture and is found to be an electrostatic double layer, with axially-separated regions of net positive and negative charge. Reducing the aperture diameter or increasing its length increases the double layer strength.

  1. Particle-in-Cell Modeling of Magnetized Argon Plasma Flow Through Small Mechanical Apertures

    International Nuclear Information System (INIS)

    Sefkow, Adam B.; Cohen, Samuel A.

    2009-01-01

    Motivated by observations of supersonic argon-ion flow generated by linear helicon-heated plasma devices, a three-dimensional particle-in-cell (PIC) code is used to study whether stationary electrostatic layers form near mechanical apertures intersecting the flow of magnetized plasma. By self-consistently evaluating the temporal evolution of the plasma in the vicinity of the aperture, the PIC simulations characterize the roles of the imposed aperture and applied magnetic field on ion acceleration. The PIC model includes ionization of a background neutral-argon population by thermal and superthermal electrons, the latter found upstream of the aperture. Near the aperture, a transition from a collisional to a collisionless regime occurs. Perturbations of density and potential, with mm wavelengths and consistent with ion acoustic waves, propagate axially. An ion acceleration region of length ∼ 200-300 λ D,e forms at the location of the aperture and is found to be an electrostatic double layer, with axially-separated regions of net positive and negative charge. Reducing the aperture diameter or increasing its length increases the double layer strength

  2. Three dimensional fracture aperture and porosity distribution using computerized tomography

    Science.gov (United States)

    Wenning, Q.; Madonna, C.; Joss, L.; Pini, R.

    2017-12-01

    A wide range of geologic processes and geo-engineered applications are governed by coupled hydromechanical properties in the subsurface. In geothermal energy reservoirs, quantifying the rate of heat transfer is directly linked with the transport properties of fractures, underscoring the importance of fracture aperture characterization for achieving optimal heat production. In this context, coupled core-flooding experiments with non-invasive imaging techniques (e.g., X-Ray Computed Tomography - X-Ray CT) provide a powerful method to make observations of these properties under representative geologic conditions. This study focuses on quantifying fracture aperture distribution in a fractured westerly granite core by using a recently developed calibration-free method [Huo et al., 2016]. Porosity is also estimated with the X-ray saturation technique using helium and krypton gases as saturating fluids, chosen for their high transmissibility and high CT contrast [e.g., Vega et al., 2014]. The westerly granite sample (diameter: 5 cm, length: 10 cm) with a single through-going rough-walled fracture was mounted in a high-pressure aluminum core-holder and placed inside a medical CT scanner for imaging. During scanning the pore fluid pressure was undrained and constant, and the confining pressure was regulated to have the desired effective pressure (0.5, 5, 7 and 10 MPa) under loading and unloading conditions. 3D reconstructions of the sample have been prepared in terms of fracture aperture and porosity at a maximum resolution of (0.24×0.24×1) mm3. Fracture aperture maps obtained independently using helium and krypton for the whole core depict a similar heterogeneous aperture field, which is also dependent on confining pressure. Estimates of the average hydraulic aperture from CT scans are in quantitative agreement with results from fluid flow experiments. However, the latter lack of the level of observational detail achieved through imaging, which further evidence the

  3. On-axis parallel ion speeds near mechanical and magnetic apertures in a helicon plasma device

    International Nuclear Information System (INIS)

    Sun Xuan; Cohen, S.A.; Scime, Earl E.; Miah, Mahmood

    2005-01-01

    Using laser-induced fluorescence, measurements of parallel ion velocities were made along the axis of a helicon-generated Ar plasma column whose radius was modified by spatially separated mechanical and magnetic apertures. Ion acceleration to supersonic speeds was observed 0.1-5 cm downstream of both aperture types, simultaneously generating two steady-state double layers (DLs) when both apertures were in place. The DL downstream of the mechanical aperture plate had a larger potential drop, Δφ DL =6-9 kT e , compared to the DL downstream of the magnetic aperture, Δφ DL ∼3 kT e . In the presheath region upstream of the mechanical aperture, the convective ion speed increased over a collisional distance; from stagnant at 4 cm from the aperture to the 1.4 times the sound speed at the aperture. The dependence of the free- and trapped-ion-velocity-distribution functions on the magnetic-field strength and mechanical-aperture electrical bias are also presented

  4. Fabrication and Properties of Silica Gel/Calcium Sulfate/Strontium-doped β-tricalcium Phosphate Composite Porous Scaffolds for Bone Tissue Engineering

    Directory of Open Access Journals (Sweden)

    QIN Xiao-su

    2018-03-01

    Full Text Available The calcium sulfate/strontium-doped β-tricalcium phosphate composite spherical pellets was fabricated, using the calcium sulfate/strontium-doped β-TCP as raw material, and through the stirring spray drying method, and then composite spherical pellets were combined with silica gel, porous silica gel/calcium sulfate/strontium-doped β-tricalcium phosphate scaffold was obtained by stacking aggregation method in the mould. The XRD, SEM and FT-IR, etc are employed to examine the chemical composition, composite morphology and structure characteristics, and the degradability, porosity, mechanical properties and cytotoxicity of the scaffolds materials were studied. The results reveal that the composite porous scaffolds have irregular pore structure with pore size between 0.2-1.0mm, and they have a large number of micropores on each of the composite spherical pellets, with the aperture between 50-200μm. Moreover, the porosity of the composite scaffolds is about 62%, which can meet the requirements of scaffolds for bone tissue engineering in porosity; the cytotoxicity tests show the composite scaffolds have no cytotoxic effect and it has good degradation. Therefore, it has good application prospect in bone tissue engineering of the bone defect repair of non-bearing site.

  5. Microporous Silica Based Membranes for Desalination

    Directory of Open Access Journals (Sweden)

    João C. Diniz da Costa

    2012-09-01

    Full Text Available This review provides a global overview of microporous silica based membranes for desalination via pervaporation with a focus on membrane synthesis and processing, transport mechanisms and current state of the art membrane performance. Most importantly, the recent development and novel concepts for improving the hydro-stability and separating performance of silica membranes for desalination are critically examined. Research into silica based membranes for desalination has focussed on three primary methods for improving the hydro-stability. These include incorporating carbon templates into the microporous silica both as surfactants and hybrid organic-inorganic structures and incorporation of metal oxide nanoparticles into the silica matrix. The literature examined identified that only metal oxide silica membranes have demonstrated high salt rejections under a variety of feed concentrations, reasonable fluxes and unaltered performance over long-term operation. As this is an embryonic field of research several target areas for researchers were discussed including further improvement of the membrane materials, but also regarding the necessity of integrating waste or solar heat sources into the final process design to ensure cost competitiveness with conventional reverse osmosis processes.

  6. Synthesis and application of silica gel modified with alkoxyalcohols. Alkoxyalcohol shushoku silica gel no gosei to riyo

    Energy Technology Data Exchange (ETDEWEB)

    Moriguchi, T.; Ishiguro, H.; Matsubara, Y.; Yoshihara, M.; Maeshima, T.; Ito, S. (Kinki University, Osaka (Japan). Faculty of Science and Engineering)

    1991-08-20

    Several kinds of silica gel modified by alkoxyalcohols were synthesized by refluxing and dehyration and the organic reactions were studied when these silica gels were used as the catalyst. It could be confirmed by FT-IR spectra, DTA and elementary analysis that alkoxylalcohols adhere to the surface of silica gels without any decomposition. The acetate was produced by using alkyl halides. It was found that the modified silica gels had clearly the catalytic action for the reaction with n-hexyl bromide and dibromoethane although unmodified silica gels did not show the catalytic action. The reducing reaction of carbonyl compounds was carried out. The reaction proceeded at 25 centigrade for acetophenone, cyclohexanone, 1-indanone and 2-octanone to produce the corresponding reduction products. 11 refs., 5 figs., 4 tabs.

  7. Fungal Systematics and Evolution: FUSE 1

    NARCIS (Netherlands)

    Crous, Pedro W; Schumacher, René K; Wingfield, Michael J; Lombard, Lorenzo; Giraldo, Alejandra; Christensen, Martha; Gardiennet, Alain; Nakashima, Chiharu; Pereira, Olinto L; Smith, Alexander J; Groenewald, Johannes Z

    2015-01-01

    Fungal Systematics and Evolution (FUSE) is introduced as a new series to expedite the publication of issues relating to the epitypification of formerly described species, report new sexual-asexual connections, the merging of sexual and asexual gen¬era following the end of dual nomenclature, and to

  8. Acoustic Source Localization via Subspace Based Method Using Small Aperture MEMS Arrays

    Directory of Open Access Journals (Sweden)

    Xin Zhang

    2014-01-01

    Full Text Available Small aperture microphone arrays provide many advantages for portable devices and hearing aid equipment. In this paper, a subspace based localization method is proposed for acoustic source using small aperture arrays. The effects of array aperture on localization are analyzed by using array response (array manifold. Besides array aperture, the frequency of acoustic source and the variance of signal power are simulated to demonstrate how to optimize localization performance, which is carried out by introducing frequency error with the proposed method. The proposed method for 5 mm array aperture is validated by simulations and experiments with MEMS microphone arrays. Different types of acoustic sources can be localized with the highest precision of 6 degrees even in the presence of wind noise and other noises. Furthermore, the proposed method reduces the computational complexity compared with other methods.

  9. Translation symmetry of the Fraunhofer diffraction pattern from a polygonal aperture

    International Nuclear Information System (INIS)

    Vinogradov, I.R.; Tarlykov, V.A.

    1995-01-01

    The problem of observing the translation symmetry in the Fraunhofer diffraction pattern is treated. The objective of this study is to show that translation symmetry can be observed in the Fraunhofer diffraction pattern if the diffraction aperture can be represented in the form of a set of parallelogram apertures. It is shown that the diffraction field produced by such an aperture can be represented as a system of point sources modulated with an amplitude factor. 10 refs., 2 figs

  10. Dynamic aperture studies for SPEAR 3

    International Nuclear Information System (INIS)

    Nosochkov, Y.; Corbett, J.

    1999-01-01

    The Stanford Synchrotron Radiation Laboratory is investigating an accelerator upgrade project that would replace the present 130 nm·rad FODO lattice with an 18 nm·rad double bend achromat (DBA) lattice: SPEAR 3. The low emittance design yields a high brightness beam, but the stronger focusing in the DBA lattice increases chromaticity and beam sensitivity to machine errors. To ensure efficient injection and long Touschek lifetime, an optimization of the design lattice and dynamic aperture has been performed. In this paper, we review the methods used to maximize the SPEAR 3 dynamic aperture including necessary optics modifications, choice of tune and phase advance, optimization of sextupole and coupling correction, and modeling effects of machine errors, wigglers and lattice periodicity

  11. Transmission of high-power electron beams through small apertures

    International Nuclear Information System (INIS)

    Tschalär, C.; Alarcon, R.; Balascuta, S.; Benson, S.V.; Bertozzi, W.; Boyce, J.R.; Cowan, R.; Douglas, D.; Evtushenko, P.; Fisher, P.; Ihloff, E.; Kalantarians, N.; Kelleher, A.; Legg, R.; Milner, R.G.; Neil, G.R.; Ou, L.; Schmookler, B.; Tennant, C.; Williams, G.P.

    2013-01-01

    Tests were performed to pass a 100 MeV, 430 kWatt c.w. electron beam from the energy-recovery linac at the Jefferson Laboratory's FEL facility through a set of small apertures in a 127 mm long aluminum block. Beam transmission losses of 3 p.p.m. through a 2 mm diameter aperture were maintained during a 7 h continuous run

  12. SCC modification by use of amorphous nano-silica

    NARCIS (Netherlands)

    Quercia Bianchi, G.; Spiesz, P.R.; Hüsken, G.; Brouwers, H.J.H.

    2014-01-01

    In this study two different types of nano-silica (nS) were applied in self-compacting concrete (SCC), both having similar particle size distributions (PSD), but produced through two different processes: fumed powder silica and precipitated silica in colloidal suspension. The influence of nano-silica

  13. Agmatine attenuates silica-induced pulmonary fibrosis.

    Science.gov (United States)

    El-Agamy, D S; Sharawy, M H; Ammar, E M

    2014-06-01

    There is a large body of evidence that nitric oxide (NO) formation is implicated in mediating silica-induced pulmonary fibrosis. As a reactive free radical, NO may not only contribute to lung parenchymal tissue injury but also has the ability to combine with superoxide and form a highly reactive toxic species peroxynitrite that can induce extensive cellular toxicity in the lung tissues. This study aimed to explore the effect of agmatine, a known NO synthase inhibitor, on silica-induced pulmonary fibrosis in rats. Male Sprague Dawley rats were treated with agmatine for 60 days following a single intranasal instillation of silica suspension (50 mg in 0.1 ml saline/rat). The results revealed that agmatine attenuated silica-induced lung inflammation as it decreased the lung wet/dry weight ratio, protein concentration, and the accumulation of the inflammatory cells in the bronchoalveolar lavage fluid. Agmatine showed antifibrotic activity as it decreased total hydroxyproline content of the lung and reduced silica-mediated lung inflammation and fibrosis in lung histopathological specimen. In addition, agmatine significantly increased superoxide dismutase (p Agmatine also reduced silica-induced overproduction of pulmonary nitrite/nitrate as well as tumor necrosis factor α. Collectively, these results demonstrate the protective effects of agmatine against the silica-induced lung fibrosis that may be attributed to its ability to counteract the NO production, lipid peroxidation, and regulate cytokine effects. © The Author(s) 2014.

  14. Quench Performance of the First Twin-aperture 11 T Dipole for LHC upgrades

    CERN Document Server

    Zlobin, A V; Apollinari, G; Barzi, E; Chlachidze, G; Nobrega, A; Novitski, I; Stoynev, S; Turrioni, D; Auchmann, B; Izquierdo Bermudez, S; Karppinen, M; Rossi, L; Savary, F; Smekens, D

    2015-01-01

    FNAL and CERN are developing a twin-aperture 11 T Nb$_{3}$Sn dipole suitable for installation in the LHC. A single-aperture 2-m long dipole demonstrator and two 1-m long dipole models have been fabricated and tested at FNAL in 2012-2014. The two 1 m long collared coils were then assembled into the first twin-aperture Nb$_{3}$Sn demonstrator dipole and tested. Test results of this twin-aperture Nb$_{3}$Sn dipole model are reported and discussed.

  15. Degradability and Clearance of Silicon, Organosilica, Silsesquioxane, Silica Mixed Oxide, and Mesoporous Silica Nanoparticles

    KAUST Repository

    Croissant, Jonas G.

    2017-01-13

    The biorelated degradability and clearance of siliceous nanomaterials have been questioned worldwide, since they are crucial prerequisites for the successful translation in clinics. Typically, the degradability and biocompatibility of mesoporous silica nanoparticles (MSNs) have been an ongoing discussion in research circles. The reason for such a concern is that approved pharmaceutical products must not accumulate in the human body, to prevent severe and unpredictable side-effects. Here, the biorelated degradability and clearance of silicon and silica nanoparticles (NPs) are comprehensively summarized. The influence of the size, morphology, surface area, pore size, and surface functional groups, to name a few, on the degradability of silicon and silica NPs is described. The noncovalent organic doping of silica and the covalent incorporation of either hydrolytically stable or redox- and enzymatically cleavable silsesquioxanes is then described for organosilica, bridged silsesquioxane (BS), and periodic mesoporous organosilica (PMO) NPs. Inorganically doped silica particles such as calcium-, iron-, manganese-, and zirconium-doped NPs, also have radically different hydrolytic stabilities. To conclude, the degradability and clearance timelines of various siliceous nanomaterials are compared and it is highlighted that researchers can select a specific nanomaterial in this large family according to the targeted applications and the required clearance kinetics.

  16. Optimization of Dynamic Aperture of PEP-X Baseline Design

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Min-Huey; /SLAC; Cai, Yunhai; /SLAC; Nosochkov, Yuri; /SLAC

    2010-08-23

    SLAC is developing a long-range plan to transfer the evolving scientific programs at SSRL from the SPEAR3 light source to a much higher performing photon source. Storage ring design is one of the possibilities that would be housed in the 2.2-km PEP-II tunnel. The design goal of PEPX storage ring is to approach an optimal light source design with horizontal emittance less than 100 pm and vertical emittance of 8 pm to reach the diffraction limit of 1-{angstrom} x-ray. The low emittance design requires a lattice with strong focusing leading to high natural chromaticity and therefore to strong sextupoles. The latter caused reduction of dynamic aperture. The dynamic aperture requirement for horizontal injection at injection point is about 10 mm. In order to achieve the desired dynamic aperture the transverse non-linearity of PEP-X is studied. The program LEGO is used to simulate the particle motion. The technique of frequency map is used to analyze the nonlinear behavior. The effect of the non-linearity is tried to minimize at the given constrains of limited space. The details and results of dynamic aperture optimization are discussed in this paper.

  17. Optimization of Dynamic Aperture of PEP-X Baseline Design

    International Nuclear Information System (INIS)

    Wang, Min-Huey

    2010-01-01

    SLAC is developing a long-range plan to transfer the evolving scientific programs at SSRL from the SPEAR3 light source to a much higher performing photon source. Storage ring design is one of the possibilities that would be housed in the 2.2-km PEP-II tunnel. The design goal of PEPX storage ring is to approach an optimal light source design with horizontal emittance less than 100 pm and vertical emittance of 8 pm to reach the diffraction limit of 1-(angstrom) x-ray. The low emittance design requires a lattice with strong focusing leading to high natural chromaticity and therefore to strong sextupoles. The latter caused reduction of dynamic aperture. The dynamic aperture requirement for horizontal injection at injection point is about 10 mm. In order to achieve the desired dynamic aperture the transverse non-linearity of PEP-X is studied. The program LEGO is used to simulate the particle motion. The technique of frequency map is used to analyze the nonlinear behavior. The effect of the non-linearity is tried to minimize at the given constrains of limited space. The details and results of dynamic aperture optimization are discussed in this paper.

  18. Nondestructive detection system of faults in fuses using radioisotope

    International Nuclear Information System (INIS)

    Goncalves, D.

    1973-01-01

    A system is developed to show the viability of non-destructive detection of the faults of explosive safety fuses which are manufactured by Fabrica da Estrela do Ministerio do Exercito. The faults are detected by an ion-chamber based on the variation of the intensity of the beta particles that penetrate the fuse which passes through a collimator. The beta particles are emitted by Strontium-90 + Yttrium-90 encapsulated in either stainless steel or aluminum. The concept of 'bucking Voltage' is applied to differentiate electronically the signal generated by the ion-chamber. (author)

  19. Functionalization of silica nanoparticles for polypropylene nanocomposites applications

    International Nuclear Information System (INIS)

    Bracho, Diego; Palza, Humberto; Quijada, Raul; Dougnac, Vivianne

    2011-01-01

    Synthetic silica nanospheres of different diameters produced via the sol-gel method were used in order to enhance the barrier properties of the polypropylene-silica nanocomposites. Modification of the silica surface by reaction with organic chlorosilanes was performed in order to improve the particles interaction with the polypropylene matrix and its dispersion. Unmodified and modified silica nanoparticles were characterized using electronic microscopy (TEM), elemental analysis, thermo gravimetric analysis (TGA), and solid state nuclear magnetic resonance (NMR) spectroscopy. Preliminary permeability tests of the polymer-silica nanocomposite films showed no significant change at low particles load (3 wt%) regardless its size or surface functionality, mainly because of the low aspect ratio of the silica nanospheres. However, it is expected that at a higher concentration of silica particles differences will be observed. (author)

  20. Measurements of fuse and resistor characteristics for multi-megajoule capacitor bank application

    International Nuclear Information System (INIS)

    McDonald, K.F.; Smith, T.; Golden, J.; Conley, B.

    1986-01-01

    Experimental tests have been conducted on commercially available fuses and resistors under fast high voltage pulsed (10 μsec) conditions to determine their ability to protect capacitor bank components during faults. NRL's Modified Betatron Accelerator uses two multi-megajoule capacitor banks to power the toroidal and betatron magnetic field coils. The expensive high energy density capacitors in these banks must be protected from excessive peak current, voltage reversal, or charging beyond their electrical ratings in the occurrence of a fault. Adequate protection can be obtained with fuses and resistors in series with each parallel connected capacitor. The fuses must open reliably and hold off high voltage D.C. (10 - 20 kV), and the resistors must conduct high current and di/dt without failing from energy deposition or magnetic forces. The performance of the commercial fuses is well documented at low AC frequencies and currents (60 Hz/100 A) but data was not previously available for the fast high current pulsed conditions that prevail under actual fault conditions. A 20 kV 200 kJ, low inductance capacitor bank and ignitron switch were used to conduct the experiments. Peak currents in the fuses were approximately 170 kA at t - 6.5 μs. The final fuse hold-off voltage exceeded 8 kV. Currents in the resistors ranged from - 20 - 40 kA per resistor. The experimental results have been compared to the manufacturers data from minimum melt and maximum let-through and to exploding bridge wire computer models

  1. 30 CFR 75.601-3 - Short circuit protection; dual element fuses; current ratings; maximum values.

    Science.gov (United States)

    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 short...

  2. Toughening Mechanisms in Silica-Filled Epoxy Nanocomposites

    Science.gov (United States)

    Patel, Binay S.

    Epoxies are widely used as underfill resins throughout the microelectronics industry to mechanically couple and protect various components of flip-chip assemblies. Generally rigid materials largely surround underfill resins. Improving the mechanical and thermal properties of epoxy resins to better match those of their rigid counterparts can help extend the service lifetime of flip-chip assemblies. Recently, researchers have demonstrated that silica nanoparticles are effective toughening agents for lightly-crosslinked epoxies. Improvements in the fracture toughness of silica-filled epoxy nanocomposites have primarily been attributed to two toughening mechanisms: particle debonding with subsequent void growth and matrix shear banding. Various attempts have been made to model the contribution of these toughening mechanisms to the overall fracture energy observed in silica-filled epoxy nanocomposites. However, disparities still exist between experimental and modeled fracture energy results. In this dissertation, the thermal, rheological and mechanical behavior of eight different types of silica-filled epoxy nanocomposites was investigated. Each nanocomposite consisted of up to 10 vol% of silica nanoparticles with particle sizes ranging from 20 nm to 200 nm, with a variety of surface treatments and particle structures. Fractographical analysis was conducted with new experimental approaches in order to accurately identify morphological evidence for each proposed toughening mechanism. Overall, three major insights into the fracture behavior of real world silica-filled epoxy nanocomposites were established. First, microcracking was observed as an essential toughening mechanism in silica-filled epoxy nanocomposites. Microcracking was observed on the surface and subsurface of fractured samples in each type of silica-filled epoxy nanocomposite. The additional toughening contribution of microcracking to overall fracture energy yielded excellent agreement between experimental

  3. Comparison of PSF maxima and minima of multiple annuli coded aperture (MACA) and complementary multiple annuli coded aperture (CMACA) systems

    Science.gov (United States)

    Ratnam, Challa; Lakshmana Rao, Vadlamudi; Lachaa Goud, Sivagouni

    2006-10-01

    In the present paper, and a series of papers to follow, the Fourier analytical properties of multiple annuli coded aperture (MACA) and complementary multiple annuli coded aperture (CMACA) systems are investigated. First, the transmission function for MACA and CMACA is derived using Fourier methods and, based on the Fresnel-Kirchoff diffraction theory, the formulae for the point spread function are formulated. The PSF maxima and minima are calculated for both the MACA and CMACA systems. The dependence of these properties on the number of zones is studied and reported in this paper.

  4. Comparison of PSF maxima and minima of multiple annuli coded aperture (MACA) and complementary multiple annuli coded aperture (CMACA) systems

    International Nuclear Information System (INIS)

    Ratnam, Challa; Rao, Vadlamudi Lakshmana; Goud, Sivagouni Lachaa

    2006-01-01

    In the present paper, and a series of papers to follow, the Fourier analytical properties of multiple annuli coded aperture (MACA) and complementary multiple annuli coded aperture (CMACA) systems are investigated. First, the transmission function for MACA and CMACA is derived using Fourier methods and, based on the Fresnel-Kirchoff diffraction theory, the formulae for the point spread function are formulated. The PSF maxima and minima are calculated for both the MACA and CMACA systems. The dependence of these properties on the number of zones is studied and reported in this paper

  5. Anthracene-fused BODIPYs as near-infrared dyes with high photostability

    KAUST Repository

    Zeng, Lintao; Jiao, Chongjun; Huang, Xiaobo; Huang, Kuo-Wei; Chin, Weeshong; Wu, Jishan

    2011-01-01

    An anthracene unit was successfully fused to the zigzag edge of a boron dipyrromethene (BODIPY) core by an FeCl 3-mediated oxidative cyclodehydrogenation reaction. Meanwhile, a dimer was also formed by both intramolecular cyclization and intermolecular coupling. The anthracene-fused BODIPY monomer 7a and dimer 7b showed small energy gaps (∼1.4 eV) and near-infrared absorption/emission. Moreover, they exhibited high photostability. © 2011 American Chemical Society.

  6. Anthracene-fused BODIPYs as near-infrared dyes with high photostability

    KAUST Repository

    Zeng, Lintao

    2011-11-18

    An anthracene unit was successfully fused to the zigzag edge of a boron dipyrromethene (BODIPY) core by an FeCl 3-mediated oxidative cyclodehydrogenation reaction. Meanwhile, a dimer was also formed by both intramolecular cyclization and intermolecular coupling. The anthracene-fused BODIPY monomer 7a and dimer 7b showed small energy gaps (∼1.4 eV) and near-infrared absorption/emission. Moreover, they exhibited high photostability. © 2011 American Chemical Society.

  7. Design of a hybrid double-sideband/single-sideband (schlieren) objective aperture suitable for electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Buijsse, Bart; Laarhoven, Frank M.H.M. van [FEI Company, PO Box 80066, 5600 KA Eindhoven (Netherlands); Schmid, Andreas K.; Cambie, Rossana; Cabrini, Stefano; Jin, Jian [Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720 (United States); Glaeser, Robert M., E-mail: rmglaeser@lbl.gov [Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720 (United States)

    2011-12-15

    A novel design is described for an aperture that blocks a half-plane of the electron diffraction pattern out to a desired scattering angle, and then - except for a narrow support beam - transmits all of the scattered electrons beyond that angle. Our proposed tulip-shaped design is thus a hybrid between the single-sideband (ssb) aperture, which blocks a full half-plane of the diffraction pattern, and the conventional (i.e. fully open) double-sideband (dsb) aperture. The benefits of this hybrid design include the fact that such an aperture allows one to obtain high-contrast images of weak-phase objects with the objective lens set to Scherzer defocus. We further demonstrate that such apertures can be fabricated from thin-foil materials by milling with a focused ion beam (FIB), and that such apertures are fully compatible with the requirements of imaging out to a resolution of at least 0.34 nm. As is known from earlier work with single-sideband apertures, however, the edge of such an aperture can introduce unwanted, electrostatic phase shifts due to charging. The principal requirement for using such an aperture in a routine data-collection mode is thus to discover appropriate materials, protocols for fabrication and processing and conditions of use such that the hybrid aperture remains free of charging over long periods of time. -- Highlights: Black-Right-Pointing-Pointer New objective-aperture design is proposed for imaging weak-phase objects. Black-Right-Pointing-Pointer Design produces single-sideband contrast at low spatial frequencies. Black-Right-Pointing-Pointer Design also retains Scherzer-defocus phase contrast at higher resolution. Black-Right-Pointing-Pointer Proof-of-concept results are presented for microfabricated apertures. Black-Right-Pointing-Pointer Charging of such apertures during use remains an experimental challenge.

  8. Polar silica-based stationary phases. Part II- Neutral silica stationary phases with surface bound maltose and sorbitol for hydrophilic interaction liquid chromatography.

    Science.gov (United States)

    Rathnasekara, Renuka; El Rassi, Ziad

    2017-07-28

    Two neutral polyhydroxylated silica bonded stationary phases, namely maltose-silica (MALT-silica) and sorbitol-silica (SOR-silica), have been introduced and chromatographically characterized in hydrophilic interaction liquid chromatography (HILIC) for a wide range of polar compounds. The bonding of the maltose and sorbitol to the silica surface was brought about by first converting bare silica to an epoxy-activated silica surface via reaction with γ-glycidoxypropyltrimethoxysilane (GPTMS) followed by attaching maltose and sorbitol to the epoxy surface in the presence of the Lewis acid catalyst BF 3 .ethereate. Both silica based columns offered the expected retention characteristics usually encountered for neutral polar surface. The retention mechanism is majorly based on solute' differential partitioning between an organic rich hydro-organic mobile phase (e.g., ACN rich mobile phase) and an adsorbed water layer on the surface of the stationary phase although additional hydrogen bonding was also responsible in some cases for solute retention. The MALT-silica column proved to be more hydrophilic and offered higher retention, separation efficiency and resolution than the SOR-silica column among the tested polar solutes such as derivatized mono- and oligosaccharides, weak phenolic acids, cyclic nucleotide monophosphate and nucleotide-5'-monophosphates, and weak bases, e.g., nucleobases and nucleosides. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Soft apertures to shape high-power laser beams

    International Nuclear Information System (INIS)

    Lukishova, S.G.; Pashinin, P.P.; Batygov, S.K.; Terentiev, B.M.

    1989-01-01

    Soft or apodized apertures with smooth decreasing from center to edges transmission profiles are used in laser physics for beam shaping. This paper gives the results of the studies of four types of these units for UV, visible and IR lasers. They are made of glasses or crystals with the use of one of the following technologies: absorption induced by ionizing radiation; photodestruction of color centers or photooxidation of impurities ions; additive coloration; frustrated total internal reflection. The special feature of such apertures is their high optical damage resistance under the irradiation of single-pulse laser radiation. They are approximately 3-50 mm in diameter by the methods of making them give the possibility to create near-Gaussian and flat-top beams with dimensions less than 1 mm and larger than 200 mm. The results of using them in high-power single-pulse lasers are presented. Damage thresholds of these apertures in such types of lasers have been defined

  10. Optimized baffle and aperture placement in neutral beamlines

    International Nuclear Information System (INIS)

    Stone, R.; Duffy, T.; Vetrovec, J.

    1983-01-01

    Most neutral beamlines contain an iron-core ion-bending magnet that requires shielding between the end of the neutralizer and this magnet. This shielding allows the gas pressure to drop prior to the beam entering the magnet and therefore reduces beam losses in this drift region. We have found that the beam losses can be reduced even further by eliminating the iron-core magnet and the magnetic shielding altogether. The required bending field can be supplied by current coils without the iron poles. In addition, placement of the baffles and apertures can affect the cold gas entering the plasma region and the losses in the neutral beam due to re-ionization. In our study we varied the placement of the baffles, which determine the amount of pumping in each chamber, and the apertures, which determine the beam loss. Our results indicate that a baffle/aperture configuration can be set for either minimum cold gas into the plasma region or minimum beam losses, but not both

  11. Magnetic core-shell silica particles

    NARCIS (Netherlands)

    Claesson, E.M.

    2007-01-01

    This thesis deals with magnetic silica core-shell colloids and related functionalized silica structures. Synthesis routes have been developed and optimized. The physical properties of these colloids have been investigated, such as the magnetic dipole moment, dipolar structure formation and

  12. 30 CFR 75.601-2 - Short circuit protection; use of fuses; approval by the Secretary.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Short circuit protection; use of fuses... Trailing Cables § 75.601-2 Short circuit protection; use of fuses; approval by the Secretary. Fuses shall not be employed to provide short circuit protection for trailing cables unless specifically approved...

  13. Complementary bowtie aperture for localizing and enhancing optical magnetic field

    Science.gov (United States)

    Zhou, Nan; Kinzel, Edward C.; Xu, Xianfan

    2011-08-01

    Nanoscale bowtie antenna and bowtie aperture antenna have been shown to generate strongly enhanced and localized electric fields below the diffraction limit in the optical frequency range. According to Babinet's principle, their complements will be efficient for concentrating and enhancing magnetic fields. In this Letter, we discuss the enhancement of magnetic field intensity of nanoscale complementary bowtie aperture as well as complementary bowtie aperture antenna, or diabolo nanoantenna. We show that the complementary bowtie antenna resonates at a smaller wavelength and thus is more suitable for applications near visible wavelengths. The near-field magnetic intensity can be further enhanced by the addition of groove structures that scatter surface plasmon.

  14. Peak stresses shift from femoral tunnel aperture to tibial tunnel aperture in lateral tibial tunnel ACL reconstructions: a 3D graft-bending angle measurement and finite-element analysis.

    Science.gov (United States)

    Van Der Bracht, Hans; Tampere, Thomas; Beekman, Pieter; Schepens, Alexander; Devriendt, Wouter; Verdonk, Peter; Victor, Jan

    2018-02-01

    To investigate the effect of tibial tunnel orientation on graft-bending angle and stress distribution in the ACL graft. Eight cadaveric knees were scanned in extension, 45°, 90°, and full flexion. 3D reconstructions with anatomically placed anterior cruciate ligament (ACL) grafts were constructed with Mimics 14.12 ® . 3D graft-bending angles were measured for classic medial tibial tunnels (MTT) and lateral tibial tunnels (LTT) with different drill-guide angles (DGA) (45°, 55°, 65°, and 75°). A pivot shift was performed on 1 knee in a finite-element analysis. The peak stresses in the graft were calculated for eight different tibial tunnel orientations. In a classic anatomical ACL repair, the largest graft-bending angle and peak stresses are seen at the femoral tunnel aperture. The use of a different DGA at the tibial side does not change the graft-bending angle at the femoral side or magnitude of peak stresses significantly. When using LTT, the largest graft-bending angles and peak stresses are seen at the tibial tunnel aperture. In a classic anatomical ACL repair, peak stresses in the ACL graft are found at the femoral tunnel aperture. When an LTT is used, peak stresses are similar compared to classic ACL repairs, but the location of the peak stress will shift from the femoral tunnel aperture towards the tibial tunnel aperture. the risk of graft rupture is similar for both MTTs and LTTs, but the location of graft rupture changes from the femoral tunnel aperture towards the tibial tunnel aperture, respectively. I.

  15. Metrology measurements for large-aperture VPH gratings

    Science.gov (United States)

    Zheng, Jessica R.; Gers, Luke; Heijmans, Jeroen

    2013-09-01

    The High Efficiency and Resolution Multi Element Spectrograph (HERMES) for the Australian Astronomical Observatory (AAO) uses four large aperture, high angle of incidence volume phase holographic gratings (VPHG) for high resolution `Galactic archaeology' spectroscopy. The large clear aperture, the high diffraction efficiency, the line frequency homogeneity, and mosaic alignment made manufacturing and testing challenging. We developed new metrology systems at the AAO to verify the performance of these VPH gratings. The measured diffraction efficiencies and line frequency of the VPH gratings received so far meet the vendor's provided data. The wavefront quality for the Blue VPH grating is good but the Green and Red VPH gratings need to be post polishing.

  16. An examination of the number of required apertures for step-and-shoot IMRT

    International Nuclear Information System (INIS)

    Jiang, Z; Earl, M A; Zhang, G W; Yu, C X; Shepard, D M

    2005-01-01

    We have examined the degree to which step-and-shoot IMRT treatment plans can be simplified (using a small number of apertures) without sacrificing the dosimetric quality of the plans. A key element of this study was the use of direct aperture optimization (DAO), an inverse planning technique where all of the multi-leaf collimator constraints are incorporated into the optimization. For seven cases (1 phantom, 1 prostate, 3 head-and-neck and 2 lung), DAO was used to perform a series of optimizations where the number of apertures per beam direction varied from 1 to 15. In this work, we attempt to provide general guidelines for how many apertures per beam direction are sufficient for various clinical cases using DAO. Analysis of the optimized treatment plans reveals that for most cases, only modest improvements in the objective function and the corresponding DVHs are seen beyond 5 apertures per beam direction. However, for more complex cases, some dosimetric gain can be achieved by increasing the number of apertures per beam direction beyond 5. Even in these cases, however, only modest improvements are observed beyond 9 apertures per beam direction. In our clinical experience, 38 out of the first 40 patients treated using IMRT plans produced using DAO were treated with 9 or fewer apertures per beam direction. The results indicate that many step-and-shoot IMRT treatment plans delivered today are more complex than necessary and can be simplified without sacrificing plan quality

  17. Synthetic Aperture Sequential Beamformation applied to medical imaging

    DEFF Research Database (Denmark)

    Hemmsen, Martin Christian; Hansen, Jens Munk; Jensen, Jørgen Arendt

    2012-01-01

    Synthetic Aperture Sequential Beamforming (SASB) is applied to medical ultrasound imaging using a multi element convex array transducer. The main motivation for SASB is to apply synthetic aperture techniques without the need for storing RF-data for a number of elements and hereby devise a system...... with a reduced system complexity. Using a 192 element, 3.5 MHz, λ-pitch transducer, it is demonstrated using tissue-phantom and wire-phantom measurements, how the speckle size and the detail resolution is improved compared to conventional imaging....

  18. Control of aperture closure during reach-to-grasp movements in parkinson’s disease

    Science.gov (United States)

    Rand, M. K.; Smiley-Oyen, A. L.; Shimansky, Y. P.; Bloedel, J. R.; Stelmach, G. E.

    2007-01-01

    This study examined whether the pattern of coordination between arm-reaching toward an object (hand transport) and the initiation of aperture closure for grasping is different between PD patients and healthy individuals, and whether that pattern is affected by the necessity to quickly adjust the reach-to-grasp movement in response to an unexpected shift of target location. Subjects reached for and grasped a vertical dowel, the location of which was indicated by illuminating one of the three dowels placed on a horizontal plane. In control conditions, target location was fixed during the trial. In perturbation conditions, target location was shifted instantaneously by switching the illumination to a different dowel during the reach. The hand distance from the target at which the subject initiated aperture closure (aperture closure distance) was similar for both the control and perturbation conditions within each group of subjects. However, that distance was significantly closer to the target in the PD group than in the control group. The timing of aperture closure initiation varied considerably across the trials in both groups of subjects. In contrast, aperture closure distance was relatively invariant, suggesting that aperture closure initiation was determined by spatial parameters of arm kinematics rather than temporal parameters. The linear regression analysis of aperture closure distance showed that the distance was highly predictable based on the following three parameters: the amplitude of maximum grip aperture, hand velocity, and hand acceleration. This result implies that a control law, the arguments of which include the above parameters, governs the initiation of aperture closure. Further analysis revealed that the control law was very similar between the subject groups under each condition as well as between the control and perturbation conditions for each group. Consequently, the shorter aperture closure distance observed in PD patients apparently is a

  19. Anomalous enthalpy relaxation in vitreous silica

    DEFF Research Database (Denmark)

    Yue, Yuanzheng

    2015-01-01

    scans. It is known that the liquid fragility (i.e., the speed of the viscous slow-down of a supercooled liquid at its Tg during cooling) has impact on enthalpy relaxation in glass. Here, we find that vitreous silica (as a strong system) exhibits striking anomalies in both glass transition and enthalpy...... relaxation compared to fragile oxide systems. The anomalous enthalpy relaxation of vitreous silica is discovered by performing the hyperquenching-annealing-calorimetry experiments. We argue that the strong systems like vitreous silica and vitreous Germania relax in a structurally cooperative manner, whereas...... the fragile ones do in a structurally independent fashion. We discuss the origin of the anomalous enthalpy relaxation in the HQ vitreous silica....

  20. Imaging with Synthetic Aperture Radar

    CERN Document Server

    Massonnet, Didier

    2008-01-01

    Describing a field that has been transformed by the recent availability of data from a new generation of space and airborne systems, the authors offer a synthetic geometrical approach to the description of synthetic aperture radar, one that addresses physicists, radar specialists, as well as experts in image processing.  

  1. Crossed fused renal ectopia: Challenges in diagnosis and management

    Directory of Open Access Journals (Sweden)

    Shailesh Solanki

    2013-01-01

    Full Text Available 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.

  2. Mesoporous Silica from Rice Husk Ash

    Directory of Open Access Journals (Sweden)

    S.A. Mandavgane

    2010-12-01

    Full Text Available Mesoporous silica is used as a raw material in several areas: in preparation of catalysts, in inks, as aconcrete hardening accelerator, as a component of detergents and soaps, as a refractory constituent etc.Sodium silicate is produced by reacting rice hull ash (RHA with aqueous NaOH and silica is precipitatedfrom the sodium silicate by acidification. In the present work, conversion of about 90% of silica containedin RHA into sodium silicate was achieved in an open system at temperatures of about 100 °C. The resultsshowed that silica obtained from RHA is mesoporous, has a large surface area and small particle size.Rice Husk is usually mixed with coal and this mixture is used for firing boilers. The RHA therefore, usuallycontains carbon particles. Activated carbon embedded on silica has been prepared using the carbon alreadypresent in RHA. This carbon shows good adsorption capacity. ©2010 BCREC UNDIP. All rights reserved(Received: 25th April 2010, Revised: 17th June 2010, Accepted: 24th June 2010[How to Cite: V.R. Shelke, S.S. Bhagade, S.A. Mandavgane. (2010. Mesoporous Silica from Rice Husk Ash. Bulletin of Chemical Reaction Engineering and Catalysis, 5 (2: 63-67. doi:10.9767/bcrec.5.2.793.63-67

  3. Practical Hydrogen Loading of Air Silica Fibres

    DEFF Research Database (Denmark)

    Sørensen, Henrik Rokkjær; Jensen, Jesper Bevensee; Jensen, Jesper Bo Damm

    2005-01-01

    A method for hydrogen-loading air-silica optical fibres has been developed allowing out-diffusion times comparable to standard step-index fibres. Examples of the first grating written in Ge-doped air-silica fibres using a 266nm UV-laser are shown.......A method for hydrogen-loading air-silica optical fibres has been developed allowing out-diffusion times comparable to standard step-index fibres. Examples of the first grating written in Ge-doped air-silica fibres using a 266nm UV-laser are shown....

  4. Large-aperture plasma-assisted deposition of inertial confinement fusion laser coatings.

    Science.gov (United States)

    Oliver, James B; Kupinski, Pete; Rigatti, Amy L; Schmid, Ansgar W; Lambropoulos, John C; Papernov, Semyon; Kozlov, Alexei; Spaulding, John; Sadowski, Daniel; Chrzan, Z Roman; Hand, Robert D; Gibson, Desmond R; Brinkley, Ian; Placido, Frank

    2011-03-20

    Plasma-assisted electron-beam evaporation leads to changes in the crystallinity, density, and stresses of thin films. A dual-source plasma system provides stress control of large-aperture, high-fluence coatings used in vacuum for substrates 1m in aperture.

  5. Deliverable navigation for multicriteria IMRT treatment planning by combining shared and individual apertures

    International Nuclear Information System (INIS)

    Fredriksson, Albin; Bokrantz, Rasmus

    2013-01-01

    We consider the problem of deliverable Pareto surface navigation for step-and-shoot intensity-modulated radiation therapy. This problem amounts to calculation of a collection of treatment plans with the property that convex combinations of plans are directly deliverable. Previous methods for deliverable navigation impose restrictions on the number of apertures of the individual plans, or require that all treatment plans have identical apertures. We introduce simultaneous direct step-and-shoot optimization of multiple plans subject to constraints that some of the apertures must be identical across all plans. This method generalizes previous methods for deliverable navigation to allow for treatment plans with some apertures from a collective pool and some apertures that are individual. The method can also be used as a post-processing step to previous methods for deliverable navigation in order to improve upon their plans. By applying the method to subsets of plans in the collection representing the Pareto set, we show how it can enable convergence toward the unrestricted (non-navigable) Pareto set where all apertures are individual. (paper)

  6. Effect of support on hydro-metathesis of propene: A comparative study of W(CH 3 ) 6 anchored to silica vs. silica-alumina

    KAUST Repository

    Tretiakov, Mykyta; Samantaray, Manoja; Saidi, Aya; Basset, Jean-Marie

    2018-01-01

    Hydro-metathesis of propene was carried out by using well-defined W(CH3)6 supported on silica and silica-alumina. It was observed that W(CH3)6 supported silica-alumina catalyst is much better (TON 4577) than the silica supported catalyst (TON 2104

  7. Material Considerations for Fused-Filament Fabrication of Solid Dosage Forms

    Directory of Open Access Journals (Sweden)

    Evert Fuenmayor

    2018-04-01

    Full Text Available Material choice is a fundamental consideration when it comes to designing a solid dosage form. The matrix material will ultimately determine the rate of drug release since the physical properties (solubility, viscosity, and more of the material control both fluid ingress and disintegration of the dosage form. The bulk properties (powder flow, concentration, and more of the material should also be considered since these properties will influence the ability of the material to be successfully manufactured. Furthermore, there is a limited number of approved materials for the production of solid dosage forms. The present study details the complications that can arise when adopting pharmaceutical grade polymers for fused-filament fabrication in the production of oral tablets. The paper also presents ways to overcome each issue. Fused-filament fabrication is a hot-melt extrusion-based 3D printing process. The paper describes the problems encountered in fused-filament fabrication with Kollidon® VA64, which is a material that has previously been utilized in direct compression and hot-melt extrusion processes. Formulation and melt-blending strategies were employed to increase the printability of the material. The paper defines for the first time the essential parameter profile required for successful 3D printing and lists several pre-screening tools that should be employed to guide future material formulation for the fused-filament fabrication of solid dosage forms.

  8. Altering the concentration of silica tunes the functional properties of collagen-silica composite scaffolds to suit various clinical requirements.

    Science.gov (United States)

    Perumal, Sathiamurthi; Ramadass, Satiesh Kumar; Gopinath, Arun; Madhan, Balaraman; Shanmugam, Ganesh; Rajadas, Jayakumar; Mandal, Asit Baran

    2015-12-01

    The success of a tissue engineering scaffold depends on a fine balance being achieved between the physicochemical and biological properties. This study attempts to understand the influence of silica concentration on the functional properties of collagen-silica (CS) composite scaffolds for soft tissue engineering applications. Increasing the ratio of silica to collagen (0.25, 0.5, 0.75, 1.0, 1.25, 1.5 and 2.0 w/w) gave a marked advantage in terms of improving the water uptake and compressive modulus of the CS scaffolds, while also enhancing the biological stability and the turnover time. With increase in silica concentration the water uptake and compressive modulus increased concurrently, whereas it was not so for surface porous architecture and biocompatibility which are crucial for cell adhesion and infiltration. Silica:collagen ratio of ≤1 exhibits favourable surface biocompatibility, and any further increase in silica concentration has a detrimental effect. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. High-Speed Fuses in IGBT based Voltage Source Converters

    DEFF Research Database (Denmark)

    Iov, Florin; Blaabjerg, Frede; Rasmussen, Henrik

    2005-01-01

    The demand for protection of power electronic applications has during the last couple of years increased regarding the high-power IGBT modules. Even with an active protection, a high power IGBT still has a risk of exhibiting a violent rupture in the case of a fault if IGBT fuses do not protect it...... protection. First, the problem of adding inductance in the DC-link circuit is treated, second a short discussion of the protection of the IGBT module is done, and finally, the impact of the high frequency loading on the current carrying capability of the fuses is presented....

  10. Modelling and Analysis of Proximity Effect in IGBT Fuses

    DEFF Research Database (Denmark)

    Iov, Florin; Blaabjerg, Frede; Rasmussen, Henrik

    2005-01-01

    The demand for protection of power electronic applications has during the last couple of years increased regarding the high-power IGBT modules. The consequences of electrical faults can be severe in special cases; not only on the equipment but also to people, if safety principles are not applied....... Even with an active protection, a high power IGBT still has a risk of exhibiting a violent rupture in the case of a fault if e.g. IGBT fuses are not protecting it. By introducing fuses into voltage source converters a better protection of IGBT's can be achieved. However, skin and proximity effects...

  11. Silica-Coated Liposomes for Insulin Delivery

    OpenAIRE

    Neelam Dwivedi; M. A. Arunagirinathan; Somesh Sharma; Jayesh Bellare

    2010-01-01

    Liposomes coated with silica were explored as protein delivery vehicles for their enhanced stability and improved encapsulation efficiency. Insulin was encapsulated within the fluidic phosphatidylcholine lipid vesicles by thin film hydration at pH 2.5, and layer of silica was formed above lipid bilayer by acid catalysis. The presence of silica coating and encapsulated insulin was identified using confocal and electron microscopy. The native state of insulin present in the formulation was evid...

  12. Surface-dependent chemical equilibrium constants and capacitances for bare and 3-cyanopropyldimethylchlorosilane coated silica nanochannels.

    Science.gov (United States)

    Andersen, Mathias Bækbo; Frey, Jared; Pennathur, Sumita; Bruus, Henrik

    2011-01-01

    We present a combined theoretical and experimental analysis of the solid-liquid interface of fused-silica nanofabricated channels with and without a hydrophilic 3-cyanopropyldimethylchlorosilane (cyanosilane) coating. We develop a model that relaxes the assumption that the surface parameters C(1), C(2), and pK(+) are constant and independent of surface composition. Our theoretical model consists of three parts: (i) a chemical equilibrium model of the bare or coated wall, (ii) a chemical equilibrium model of the buffered bulk electrolyte, and (iii) a self-consistent Gouy-Chapman-Stern triple-layer model of the electrochemical double layer coupling these two equilibrium models. To validate our model, we used both pH-sensitive dye-based capillary filling experiments as well as electro-osmotic current-monitoring measurements. Using our model we predict the dependence of ζ potential, surface charge density, and capillary filling length ratio on ionic strength for different surface compositions, which can be difficult to achieve otherwise. Copyright © 2010 Elsevier Inc. All rights reserved.

  13. Sequential Multicomponent Strategy for the Diastereoselective Synthesis of Densely Functionalized Spirooxindole-Fused Thiazolidines

    NARCIS (Netherlands)

    Rainoldi, Giulia; Begnini, Fabio; De Munnik, Mariska; Lo Presti, Leonardo; Vande Velde, Christophe M.L.; Orru, Romano; Lesma, Giordano; Ruijter, Eelco; Silvani, Alessandra

    2018-01-01

    We developed two Ugi-type three-component reactions of spirooxindole-fused 3-thiazolines, isocyanides, and either carboxylic acids or trimethylsilyl azide, to give highly functionalized spirooxindole-fused thiazolidines. Two diverse libraries were generated using practical and robust procedures

  14. Recycling potential for low voltage and high voltage high rupturing capacity fuse links.

    Science.gov (United States)

    Psomopoulos, Constantinos S; Barkas, Dimitrios A; Kaminaris, Stavros D; Ioannidis, George C; Karagiannopoulos, Panagiotis

    2017-12-01

    Low voltage and high voltage high-rupturing-capacity fuse links are used in LV and HV installations respectively, protecting mainly the LV and HV electricity distribution and transportation networks. The Waste Electrical and Electronic Equipment Directive (2002/96/EC) for "Waste of electrical and electronic equipment" is the main related legislation and as it concerns electrical and electronic equipment, it includes electric fuses. Although, the fuse links consist of recyclable materials, only small scale actions have been implemented for their recycling around Europe. This work presents the possibilities for material recovery from this specialized industrial waste for which there are only limited volume data. Furthermore, in order to present the huge possibilities and environmental benefits, it presents the potential for recycling of HRC fuses used by the Public Power Corporation of Greece, which is the major consumer for the country, but one of the smallest ones in Europe and globally, emphasizing in this way in the issue. According to the obtained results, fuse recycling could contribute to the effort for minimize the impacts on the environment through materials recovery and reduction of the wastes' volume disposed of in landfills. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. A novel approach to correct the coded aperture misalignment for fast neutron imaging

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, F. N.; Hu, H. S., E-mail: huasi-hu@mail.xjtu.edu.cn; Wang, D. M.; Jia, J. [School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Zhang, T. K. [Laser Fusion Research Center, CAEP, Mianyang, 621900 Sichuan (China); Jia, Q. G. [Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China)

    2015-12-15

    Aperture alignment is crucial for the diagnosis of neutron imaging because it has significant impact on the coding imaging and the understanding of the neutron source. In our previous studies on the neutron imaging system with coded aperture for large field of view, “residual watermark,” certain extra information that overlies reconstructed image and has nothing to do with the source is discovered if the peak normalization is employed in genetic algorithms (GA) to reconstruct the source image. Some studies on basic properties of residual watermark indicate that the residual watermark can characterize coded aperture and can thus be used to determine the location of coded aperture relative to the system axis. In this paper, we have further analyzed the essential conditions for the existence of residual watermark and the requirements of the reconstruction algorithm for the emergence of residual watermark. A gamma coded imaging experiment has been performed to verify the existence of residual watermark. Based on the residual watermark, a correction method for the aperture misalignment has been studied. A multiple linear regression model of the position of coded aperture axis, the position of residual watermark center, and the gray barycenter of neutron source with twenty training samples has been set up. Using the regression model and verification samples, we have found the position of the coded aperture axis relative to the system axis with an accuracy of approximately 20 μm. Conclusively, a novel approach has been established to correct the coded aperture misalignment for fast neutron coded imaging.

  16. Effects of surface-mapping corrections and synthetic-aperture focusing techniques on ultrasonic imaging

    International Nuclear Information System (INIS)

    Barna, B.A.; Johnson, J.A.

    1981-01-01

    Improvements in ultrasonic imaging that can be obtained using algorithms that map the surface of targets are evaluated. This information is incorporated in the application of synthetic-aperture focusing techniques which also have the potential to improve image resolution. Images obtained using directed-beam (flat) transducers and the focused transducers normally used for synthetic-aperture processing are quantitatively compared by using no processing, synthetic-aperture processing with no corrections for surface variations, and synthetic-aperture processing with surface mapping. The unprocessed images have relatively poor lateral resolutions because echoes from two adjacent reflectors show interference effects which prevent their identification even if the spacing is larger than the single-hole resolution. The synthetic-aperture-processed images show at least a twofold improvement in lateral resolution and greatly reduced interference effects in multiple-hole images compared to directed-beam images. Perhaps more importantly, in images of test blocks with substantial surface variations portions of the image are displaced from their actual positions by several wavelengths. To correct for this effect an algorithm has been developed for calculating the surface variations. The corrected images produced using this algorithm are accurate within the experimental error. In addition, the same algorithm, when applied to the directed-beam data, produced images that are not only accurately positioned, but that also have a resolution comparable to conventional synthetic-aperture-processed images obtained from focused-transducer data. This suggests that using synthetic-aperture processing on the type of data normally collected during directed-beam ultrasonic inspections would eliminate the need to rescan for synthetic-aperture enhancement

  17. Kinetics of silica-phase transitions

    International Nuclear Information System (INIS)

    Duffy, C.J.

    1993-07-01

    In addition to the stable silica polymorph quartz, several metastable silica phases are present in Yucca Mountain. The conversion of these phases to quartz is accompanied by volume reduction and a decrease in the aqueous silica activity, which may destabilize clinoptilolite and mordenite. The primary reaction sequence for the silica phases is from opal or glass to disordered opal-CT, followed by ordering of the opal-CT and finally by the crystallization of quartz. The ordering of opal-CT takes place in the solid state, whereas the conversion of opal-CT takes place through dissolution-reprecipitation involving the aqueous phase. It is proposed that the rate of conversion of opal-CT to quartz is controlled by diffusion of defects out of a disordered surface layer formed on the crystallizing quartz. The reaction rates are observed to be dependent on temperature, pressure, degree of supersaturation, and pH. Rate equations selected from the literature appear to be consistent with observations at Yucca Mountain

  18. Class of near-perfect coded apertures

    International Nuclear Information System (INIS)

    Cannon, T.M.; Fenimore, E.E.

    1977-01-01

    Coded aperture imaging of gamma ray sources has long promised an improvement in the sensitivity of various detector systems. The promise has remained largely unfulfilled, however, for either one of two reasons. First, the encoding/decoding method produces artifacts, which even in the absence of quantum noise, restrict the quality of the reconstructed image. This is true of most correlation-type methods. Second, if the decoding procedure is of the deconvolution variety, small terms in the transfer function of the aperture can lead to excessive noise in the reconstructed image. It is proposed to circumvent both of these problems by use of a uniformly redundant array (URA) as the coded aperture in conjunction with a special correlation decoding method. It is shown that the reconstructed image in the URA system contains virtually uniform noise regardless of the structure in the original source. Therefore, the improvement over a single pinhole camera will be relatively larger for the brighter points in the source than for the low intensity points. In the case of a large detector background noise the URA will always do much better than the single pinhole regardless of the structure of the object. In the case of a low detector background noise, the improvement of the URA over the single pinhole will have a lower limit of approximately (1/2f)/sup 1 / 2 / where f is the fraction of the field of view which is uniformly filled by the object

  19. Forensic Facial Reconstruction: Relationship Between the Alar Cartilage and Piriform Aperture.

    Science.gov (United States)

    Strapasson, Raíssa Ananda Paim; Herrera, Lara Maria; Melani, Rodolfo Francisco Haltenhoff

    2017-11-01

    During forensic facial reconstruction, facial features may be predicted based on the parameters of the skull. This study evaluated the relationships between alar cartilage and piriform aperture and nose morphology and facial typology. Ninety-six cone beam computed tomography images of Brazilian subjects (49 males and 47 females) were used in this study. OsiriX software was used to perform the following measurements: nasal width, distance between alar base insertion points, lower width of the piriform aperture, and upper width of the piriform aperture. Nasal width was associated with the lower width of the piriform aperture, sex, skeletal vertical pattern of the face, and age. The current study contributes to the improvement of forensic facial guides by identifying the relationships between the alar cartilages and characteristics of the biological profile of members of a population that has been little studied thus far. © 2017 American Academy of Forensic Sciences.

  20. Health hazards due to the inhalation of amorphous silica

    Energy Technology Data Exchange (ETDEWEB)

    Merget, R.; Bruening, T. [Research Institute for Occupational Medicine (BGFA), Bochum (Germany); Bauer, T. [Bergmannsheil, University Hospital, Department of Internal Medicine, Division of Pneumonology, Allergology and Sleep Medicine, Bochum (Germany); Kuepper, H.U.; Breitstadt, R. [Degussa-Huels Corp., Wesseling (Germany); Philippou, S. [Department of Pathology, Augusta Krankenanstalten, Bochum (Germany); Bauer, H.D. [Research Institute for Hazardous Substances (IGF), Bochum (Germany)

    2002-01-01

    Occupational exposure to crystalline silica dust is associated with an increased risk for pulmonary diseases such as silicosis, tuberculosis, chronic bronchitis, chronic obstructive pulmonary disease (COPD) and lung cancer. This review summarizes the current knowledge about the health effects of amorphous (non-crystalline) forms of silica. The major problem in the assessment of health effects of amorphous silica is its contamination with crystalline silica. This applies particularly to well-documented pneumoconiosis among diatomaceous earth workers. Intentionally manufactured synthetic amorphous silicas are without contamination of crystalline silica. These synthetic forms may be classified as (1) wet process silica, (2) pyrogenic (''thermal'' or ''fumed'') silica, and (3) chemically or physically modified silica. According to the different physico-chemical properties, the major classes of synthetic amorphous silica are used in a variety of products, e.g. as fillers in the rubber industry, in tyre compounds, as free-flow and anti-caking agents in powder materials, and as liquid carriers, particularly in the manufacture of animal feed and agrochemicals; other uses are found in toothpaste additives, paints, silicon rubber, insulation material, liquid systems in coatings, adhesives, printing inks, plastisol car undercoats, and cosmetics. Animal inhalation studies with intentionally manufactured synthetic amorphous silica showed at least partially reversible inflammation, granuloma formation and emphysema, but no progressive fibrosis of the lungs. Epidemiological studies do not support the hypothesis that amorphous silicas have any relevant potential to induce fibrosis in workers with high occupational exposure to these substances, although one study disclosed four cases with silicosis among subjects exposed to apparently non-contaminated amorphous silica. Since the data have been limited, a risk of chronic bronchitis, COPD or

  1. Health hazards due to the inhalation of amorphous silica

    International Nuclear Information System (INIS)

    Merget, R.; Bruening, T.; Bauer, T.; Kuepper, H.U.; Breitstadt, R.; Philippou, S.; Bauer, H.D.

    2002-01-01

    Occupational exposure to crystalline silica dust is associated with an increased risk for pulmonary diseases such as silicosis, tuberculosis, chronic bronchitis, chronic obstructive pulmonary disease (COPD) and lung cancer. This review summarizes the current knowledge about the health effects of amorphous (non-crystalline) forms of silica. The major problem in the assessment of health effects of amorphous silica is its contamination with crystalline silica. This applies particularly to well-documented pneumoconiosis among diatomaceous earth workers. Intentionally manufactured synthetic amorphous silicas are without contamination of crystalline silica. These synthetic forms may be classified as (1) wet process silica, (2) pyrogenic (''thermal'' or ''fumed'') silica, and (3) chemically or physically modified silica. According to the different physico-chemical properties, the major classes of synthetic amorphous silica are used in a variety of products, e.g. as fillers in the rubber industry, in tyre compounds, as free-flow and anti-caking agents in powder materials, and as liquid carriers, particularly in the manufacture of animal feed and agrochemicals; other uses are found in toothpaste additives, paints, silicon rubber, insulation material, liquid systems in coatings, adhesives, printing inks, plastisol car undercoats, and cosmetics. Animal inhalation studies with intentionally manufactured synthetic amorphous silica showed at least partially reversible inflammation, granuloma formation and emphysema, but no progressive fibrosis of the lungs. Epidemiological studies do not support the hypothesis that amorphous silicas have any relevant potential to induce fibrosis in workers with high occupational exposure to these substances, although one study disclosed four cases with silicosis among subjects exposed to apparently non-contaminated amorphous silica. Since the data have been limited, a risk of chronic bronchitis, COPD or emphysema cannot be excluded. There is no

  2. Design of a neutron penumbral-aperture microscope with 10-μm resolution

    International Nuclear Information System (INIS)

    Ress, D.; Lerche, R.A.; Ellis, R.J.; Lane, S.M.

    1990-05-01

    We are currently designing a 10-μm resolution neutron penumbral-aperture microscope to diagnose high-convergence targets at the Nova laser facility. To achieve such high resolution, the new microscope will require substantial improvements in three areas. First, we have designed thick penumbral apertures with extremely sharp cutoffs over a useful (∼100 μm) field of view; fabrication of such apertures appears feasible using gold electroplating techniques. Second, the limited field of view and required close proximity of the aperture to the target (2 cm) necessitates a durable mounting and alignment system with +25 μm accuracy. Finally, a neutron detector containing 160,000 scintillator elements is required; readout and optimization of this large array are outstanding issues. 5 refs., 3 figs

  3. Method and apparatus for shadow aperture backscatter radiography (SABR) system and protocol

    Science.gov (United States)

    Shedlock, Daniel (Inventor); Jacobs, Alan M. (Inventor); Jacobs, Sharon Auerback (Inventor); Dugan, Edward (Inventor)

    2010-01-01

    A shadow aperture backscatter radiography (SABR) system includes at least one penetrating radiation source for providing a penetrating radiation field, and at least one partially transmissive radiation detector, wherein the partially transmissive radiation detector is interposed between an object region to be interrogated and the radiation source. The partially transmissive radiation detector transmits a portion of the illumination radiation field. A shadow aperture having a plurality of radiation attenuating regions having apertures therebetween is disposed between the radiation source and the detector. The apertures provide illumination regions for the illumination radiation field to reach the object region, wherein backscattered radiation from the object is detected and generates an image by the detector in regions of the detector that are shadowed by the radiation attenuation regions.

  4. Combined Kernel-Based BDT-SMO Classification of Hyperspectral Fused Images

    Directory of Open Access Journals (Sweden)

    Fenghua Huang

    2014-01-01

    Full Text Available To solve the poor generalization and flexibility problems that single kernel SVM classifiers have while classifying combined spectral and spatial features, this paper proposed a solution to improve the classification accuracy and efficiency of hyperspectral fused images: (1 different radial basis kernel functions (RBFs are employed for spectral and textural features, and a new combined radial basis kernel function (CRBF is proposed by combining them in a weighted manner; (2 the binary decision tree-based multiclass SMO (BDT-SMO is used in the classification of hyperspectral fused images; (3 experiments are carried out, where the single radial basis function- (SRBF- based BDT-SMO classifier and the CRBF-based BDT-SMO classifier are used, respectively, to classify the land usages of hyperspectral fused images, and genetic algorithms (GA are used to optimize the kernel parameters of the classifiers. The results show that, compared with SRBF, CRBF-based BDT-SMO classifiers display greater classification accuracy and efficiency.

  5. Grassy Silica Nanoribbons and Strong Blue Luminescence

    Science.gov (United States)

    Wang, Shengping; Xie, Shuang; Huang, Guowei; Guo, Hongxuan; Cho, Yujin; Chen, Jun; Fujita, Daisuke; Xu, Mingsheng

    2016-09-01

    Silicon dioxide (SiO2) is one of the key materials in many modern technological applications such as in metal oxide semiconductor transistors, photovoltaic solar cells, pollution removal, and biomedicine. We report the accidental discovery of free-standing grassy silica nanoribbons directly grown on SiO2/Si platform which is commonly used for field-effect transistors fabrication without other precursor. We investigate the formation mechanism of this novel silica nanostructure that has not been previously documented. The silica nanoribbons are flexible and can be manipulated by electron-beam. The silica nanoribbons exhibit strong blue emission at about 467 nm, together with UV and red emissions as investigated by cathodoluminescence technique. The origins of the luminescence are attributed to various defects in the silica nanoribbons; and the intensity change of the blue emission and green emission at about 550 nm is discussed in the frame of the defect density. Our study may lead to rational design of the new silica-based materials for a wide range of applications.

  6. Characterization of silica particles prepared via urease-catalyzed urea hydrolysis and activity of urease in sol–gel silica matrix

    International Nuclear Information System (INIS)

    Kato, Katsuya; Nishida, Masakazu; Ito, Kimiyasu; Tomita, Masahiro

    2012-01-01

    Highlights: ► Silica precipitation occurred via urease-catalytic reactions. ► Higher urease activity for silica synthesis enables mesostructure of silica–urease composites. ► Urease encapsulating in silica matrix retained high activity. - Abstract: Urease templated precipitation of silica synthesized by sol–gel chemistry produces a composite material allowing high urease activity. This study investigates the structural properties of the composite material that allow for the retention of the urease hydrolysis activity. Scanning (SEM) and transmission (TEM) electron microscopy reveal that the composite has a mesoporous structure composed of closely packed spherical structures ∼20–50 nm in diameter. Brunauer–Emmett–Teller (BET) analysis revealed that the surface area and pore volume of the composite prepared under the conditions of 50 mM urea and 25 °C is relatively high (324 m 2 /g and 1.0 cm 3 /g). These values are equivalent to those of usual mesoporous silica materials synthesized from the self-assembly of triblock copolymers as organic templates. In addition, after encapsulating in a sol–gel silica matrix, urease retained high activity (∼90% of the activity compared with native urease). Our results suggest a new method for synthesizing mesoporous silica materials with highly tunable pore sizes and shapes under mild conditions.

  7. High-dynamic range compressive spectral imaging by grayscale coded aperture adaptive filtering

    Directory of Open Access Journals (Sweden)

    Nelson Eduardo Diaz

    2015-09-01

    Full Text Available The coded aperture snapshot spectral imaging system (CASSI is an imaging architecture which senses the three dimensional informa-tion of a scene with two dimensional (2D focal plane array (FPA coded projection measurements. A reconstruction algorithm takes advantage of the compressive measurements sparsity to recover the underlying 3D data cube. Traditionally, CASSI uses block-un-block coded apertures (BCA to spatially modulate the light. In CASSI the quality of the reconstructed images depends on the design of these coded apertures and the FPA dynamic range. This work presents a new CASSI architecture based on grayscaled coded apertu-res (GCA which reduce the FPA saturation and increase the dynamic range of the reconstructed images. The set of GCA is calculated in a real-time adaptive manner exploiting the information from the FPA compressive measurements. Extensive simulations show the attained improvement in the quality of the reconstructed images when GCA are employed.  In addition, a comparison between traditional coded apertures and GCA is realized with respect to noise tolerance.

  8. A method to select aperture margin in collimated spot scanning proton therapy

    International Nuclear Information System (INIS)

    Wang, Dongxu; Smith, Blake R; Gelover, Edgar; Flynn, Ryan T; Hyer, Daniel E

    2015-01-01

    The use of collimator or aperture may sharpen the lateral dose gradient for spot scanning proton therapy. However, to date, there has not been a standard method to determine the aperture margin for a single field in collimated spot scanning proton therapy. This study describes a theoretical framework to select the optimal aperture margin for a single field, and also presents the spot spacing limit required such that the optimal aperture margin exists. Since, for a proton pencil beam partially intercepted by collimator, the maximum point dose (spot center) shifts away from the original pencil beam central axis, we propose that the optimal margin should be equal to the maximum pencil beam center shift under the condition that spot spacing is small with respect to the maximum pencil beam center shift, which can be numerically determined based on beam modeling data. A test case is presented which demonstrates agreement with the prediction made based on the proposed methods. When apertures are applied in a commercial treatment planning system this method may be implemented. (note)

  9. Winter climate change and fine root biogenic silica in sugar maple trees (Acer saccharum): Implications for silica in the Anthropocene

    Science.gov (United States)

    Maguire, Timothy J.; Templer, Pamela H.; Battles, John J.; Fulweiler, Robinson W.

    2017-03-01

    Winter temperatures are projected to increase over the next century, leading to reductions in winter snowpack and increased frequency of soil freezing in many northern forest ecosystems. Here we examine biogenic silica (BSi) concentrations in sugar maple (Acer saccharum) fine roots collected from a snow manipulation experiment at Hubbard Brook Experimental Forest (New Hampshire, USA). Increased soil freezing significantly lowered the BSi content of sugar maple fine roots potentially decreasing their capacity to take up water and dissolved nutrients. The reduced silica uptake (8 ± 1 kmol silica km-2) by sugar maple fine roots is comparable to silica export from temperate forest watersheds. We estimate that fine roots account for 29% of sugar maple BSi, despite accounting for only 4% of their biomass. These results suggest that increased frequency of soil freezing will reduce silica uptake by temperate tree roots, thereby changing silica availability in downstream receiving waters.

  10. Mesoporous Silica from Rice Husk Ash

    Directory of Open Access Journals (Sweden)

    V.R. Shelke

    2011-01-01

    Full Text Available Mesoporous silica is used as a raw material in several areas: in preparation of catalysts, in inks, as a concrete hardening accelerator, as a component of detergents and soaps, as a refractory constituent etc. Sodium silicate is produced by reacting rice hull ash (RHA with aqueous NaOH and silica is precipitated from the sodium silicate by acidification. In the present work, conversion of about 90% of silica contained in RHA into sodium silicate was achieved in an open system at temperatures of about 100 °C. The results showed that silica obtained from RHA is mesoporous, has a large surface area and small particle size. Rice Husk is usually mixed with coal and this mixture is used for firing boilers. The RHA therefore, usually contains carbon particles. Activated carbon embedded on silica has been prepared using the carbon already present in RHA. This carbon shows good adsorption capacity. ©2010 BCREC UNDIP. All rights reserved(Received: 25th April 2010, Revised: 17th June 2010, Accepted: 24th June 2010[How to Cite: V.R. Shelke, S.S. Bhagade, S.A. Mandavgane. (2010. Mesoporous Silica from Rice Husk Ash. Bulletin of Chemical Reaction Engineering and Catalysis, 5 (2: 63-67. doi:10.9767/bcrec.5.2.793.63-67][DOI: http://dx.doi.org/10.9767/bcrec.5.2.793.63-67

  11. Production and Application of Olivine Nano-Silica in Concrete

    Science.gov (United States)

    Mardiana, Oesman; Haryadi

    2017-05-01

    The aim of this research was to produce nano silica by synthesis of nano silica through extraction and dissolution of ground olivine rock, and applied the nano silica in the design concrete mix. The producing process of amorphous silica used sulfuric acid as the dissolution reagent. The separation of ground olivine rock occurred when the rock was heated in a batch reactor containing sulfuric acid. The results showed that the optimum mole ratio of olivine- acid was 1: 8 wherein the weight ratio of the highest nano silica generated. The heating temperature and acid concentration influenced the mass of silica produced, that was at temperature of 90 °C and 3 M acid giving the highest yield of 44.90%. Characterization using Fourier Transform Infrared (FTIR ) concluded that amorphous silica at a wavenumber of 1089 cm-1 indicated the presence of siloxane, Si-O-Si, stretching bond. Characterization using Scanning Electron Microscope - Energy Dispersive Spectroscopy (SEM-EDS) showed the surface and the size of the silica particles. The average size of silica particles was between 1-10 μm due to the rapid aggregation of the growing particles of nano silica into microparticles, caused of the pH control was not fully achieved.

  12. Digital filtering and reconstruction of coded aperture images

    International Nuclear Information System (INIS)

    Tobin, K.W. Jr.

    1987-01-01

    The real-time neutron radiography facility at the University of Virginia has been used for both transmission radiography and computed tomography. Recently, a coded aperture system has been developed to permit the extraction of three dimensional information from a low intensity field of radiation scattered by an extended object. Short wave-length radiations (e.g. neutrons) are not easily image because of the difficulties in achieving diffraction and refraction with a conventional lens imaging system. By using a coded aperture approach, an imaging system has been developed that records and reconstructs an object from an intensity distribution. This system has a signal-to-noise ratio that is proportional to the total open area of the aperture making it ideal for imaging with a limiting intensity radiation field. The main goal of this research was to develope and implement the digital methods and theory necessary for the reconstruction process. Several real-time video systems, attached to an Intellect-100 image processor, a DEC PDP-11 micro-computer, and a Convex-1 parallel processing mainframe were employed. This system, coupled with theoretical extensions and improvements, allowed for retrieval of information previously unobtainable by earlier optical methods. The effect of thermal noise, shot noise, and aperture related artifacts were examined so that new digital filtering techniques could be constructed and implemented. Results of image data filtering prior to and following the reconstruction process are reported. Improvements related to the different signal processing methods are emphasized. The application and advantages of this imaging technique to the field of non-destructive testing are also discussed

  13. Strategies used to walk through a moving aperture.

    Science.gov (United States)

    Cinelli, Michael E; Patla, Aftab E; Allard, Fran

    2008-05-01

    The objectives of the study were to determine what strategy (pursuit or interception) individuals used to pass through an oscillating target and to determine if individuals walked towards where they were looking. Kinematic and gaze behaviour data was collected from seven healthy female participants as they started at one of five different starting positions and walked 7 m towards an oscillating target. The target was a two-dimensional 70 cm aperture made by two-76 cm wide doors and oscillated between two end posts that were 300 cm apart. In order to quantify the objectives, target-heading angles [Fajen BR, Warren WH. Behavioral dynamics of steering, obstacle avoidance, and route selection. J Exp Psychol Hum Percept Perform 2003;29(2):343-62; Fajen BR, Warren WH. Visual guidance of intercepting a moving target on foot. Perception 2004;33:689-715] were calculated. Results showed that the participants used neither an interception nor a pursuit strategy to successfully pass through the moving aperture. The participants steered towards the middle of the pathway prior to passing through the middle of the aperture. A cross correlation between the horizontal gaze locations and the medial/lateral (M/L) location of the participants' center of mass (COM) was performed. The results from the cross correlation show that during the final 2s prior to crossing the aperture, the participants walked where they were looking. The findings from this study suggest that individuals simplify a task by decreasing the perceptual load until the final stages. In this way the final stages of this task were visually driven.

  14. Scaling Laws for Dynamic Aperture due to Chromatic Sextupoles

    CERN Document Server

    Scandale, Walter

    1997-01-01

    Scaling laws for the dynamic aperture due to chromatic sextupoles are investigated. The problem is addressed in a simplified lattice model containing 4 N identical cells and one linear betatron phase shifter to break the overall cell-lattice symmetry. Two families of chromatic sextupoles are used to compensate the natural chromaticity. Analytical formulae for the dynamic apertur as a function of the number of cells and of the cell length are found and confirmed through computer tracking.

  15. Phase Centers of Subapertures in a Tapered Aperture Array.

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin W. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Bickel, Douglas L. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

    2015-11-01

    Antenna apertures that are tapered for sidelobe control can also be parsed into subapertures for Direction of Arrival (DOA) measurements. However, the aperture tapering complicates phase center location for the subapertures, knowledge of which is critical for proper DOA calculation. In addition, tapering affects subaperture gains, making gain dependent on subaperture position. Techniques are presented to calculate subaperture phase center locations, and algorithms are given for equalizing subapertures’ gains. Sidelobe characteristics and mitigation are also discussed.

  16. Pumping Iron and Silica Bodybuilding

    Science.gov (United States)

    Mcnair, H.; Brzezinski, M. A.; Krause, J. W.; Parker, C.; Brown, M.; Coale, T.; Bruland, K. W.

    2016-02-01

    The availability of dissolved iron influences the stoichiometry of nutrient uptake by diatoms. Under nutrient replete conditions diatoms consume silicic acid and nitrate in a 1:1 ratio, this ratio increases under iron stress. Using the tracers 32Si and PDMPO, the total community and group-specific silica production rates were measured along a gradient of dissolved iron in an upwelling plume off the California coast. At each station, a control (ambient silicic acid) and +20 µM silicic acid treatment were conducted with each tracer to determine whether silicic acid limitation controlled the rate of silica production. Dissolved iron was 1.3 nmol kg-1 nearshore and decreased to 0.15 nmol kg-1 offshore. Silicic acid decreased more rapidly than nitrate, it was nearly 9 µM higher in the nearshore and 7 µM lower than nitrate in the middle of the transect where the iron concentration had decreased. The rate of diatom silica production decreased in tandem with silicic acid concentration, and silica production limitation by low silicic acid was most pronounced when iron concentrations were >0.4 nmol kg-1. The composition of the diatom assemblage shifted from Chaetoceros spp. dominated nearshore to a more sparse pennate-dominated assemblage offshore. Changes in taxa-specific silica production rates will be reported based on examination of PDMPO labeled cells using confocal microscopy.

  17. MEGARA Optics: Sub-aperture Stitching Interferometry for Large Surfaces

    Science.gov (United States)

    Aguirre-Aguirre, Daniel; Carrasco, Esperanza; Izazaga-Pérez, Rafael; Páez, Gonzalo; Granados-Agustín, Fermín; Percino-Zacarías, Elizabeth; Gil de Paz, Armando; Gallego, Jesús; Iglesias-Páramo, Jorge; Villalobos-Mendoza, Brenda

    2018-04-01

    In this work, we present a detailed analysis of sub-aperture interferogram stitching software to test circular and elliptical clear apertures with diameters and long axes up to 272 and 180 mm, respectively, from the Multi-Espectrógrafo en GTC de Alta Resolución para Astronomía (MEGARA). MEGARA is a new spectrograph for the Gran Telescopio Canarias (GTC). It offers a resolution between 6000 and 20000 via the use of volume phase holographic gratings. It has an integral field unit and a set of robots for multi-object spectroscopy at the telescope focal plane. The output end of the fibers forms the spectrograph pseudo-slit. The fixed geometry of the collimator and camera configuration requires prisms in addition to the flat windows of the volume phase holographic gratings. There are 73 optical elements of large aperture and high precision manufactured in Mexico at the Instituto Nacional de Astrofísica, Óptica y Electrónica (INAOE) and the Centro de Investigaciones en Óptica (CIO). The principle of stitching interferometry is to divide the surface being tested into overlapping small sections, which allows an easier analysis (Kim & Wyant 1981). This capability is ideal for non-contact tests for unique and large optics as required by astronomical instruments. We show that the results obtained with our sub-aperture stitching algorithm were consistent with other methods that analyze the entire aperture. We used this method to analyze the 24 MEGARA prisms that could not be tested otherwise. The instrument has been successfully commissioned at GTC in all the spectral configurations. The fulfillment of the irregularity specifications was one of the necessary conditions to comply with the spectral requirements.

  18. Apparatus and method for deterministic control of surface figure during full aperture polishing

    Science.gov (United States)

    Suratwala, Tayyab Ishaq; Feit, Michael Dennis; Steele, William Augustus

    2013-11-19

    A polishing system configured to polish a lap includes a lap configured to contact a workpiece for polishing the workpiece; and a septum configured to contact the lap. The septum has an aperture formed therein. The radius of the aperture and radius the workpiece are substantially the same. The aperture and the workpiece have centers disposed at substantially the same radial distance from a center of the lap. The aperture is disposed along a first radial direction from the center of the lap, and the workpiece is disposed along a second radial direction from the center of the lap. The first and second radial directions may be opposite directions.

  19. Effect of silica particle size on macrophage inflammatory responses.

    Directory of Open Access Journals (Sweden)

    Toshimasa Kusaka

    Full Text Available Amorphous silica particles, such as nanoparticles (<100 nm diameter particles, are used in a wide variety of products, including pharmaceuticals, paints, cosmetics, and food. Nevertheless, the immunotoxicity of these particles and the relationship between silica particle size and pro-inflammatory activity are not fully understood. In this study, we addressed the relationship between the size of amorphous silica (particle dose, diameter, number, and surface area and the inflammatory activity (macrophage phagocytosis, inflammasome activation, IL-1β secretion, cell death and lung inflammation. Irrespective of diameter size, silica particles were efficiently internalized by mouse bone marrow-derived macrophages via an actin cytoskeleton-dependent pathway, and induced caspase-1, but not caspase-11, activation. Of note, 30 nm-1000 nm diameter silica particles induced lysosomal destabilization, cell death, and IL-1β secretion at markedly higher levels than did 3000 nm-10000 nm silica particles. Consistent with in vitro results, intra-tracheal administration of 30 nm silica particles into mice caused more severe lung inflammation than that of 3000 nm silica particles, as assessed by measurement of pro-inflammatory cytokines and neutrophil infiltration in bronchoalveolar lavage fluid of mice, and by the micro-computed tomography analysis. Taken together, these results suggest that silica particle size impacts immune responses, with submicron amorphous silica particles inducing higher inflammatory responses than silica particles over 1000 nm in size, which is ascribed not only to their ability to induce caspase-1 activation but also to their cytotoxicity.

  20. Pecan drying with silica gel

    Energy Technology Data Exchange (ETDEWEB)

    Ghate, S.R.; Chhinnan, M.S.

    1983-07-01

    High moisture in-shell pecans were dried by keeping them in direct and indirect contact with silica gel to investigate their drying characteristics. In-shell pecans were also dried with ambient air from a controlled environment chamber and with air dehumidified by silica gel. Direct contact and dehumidified air drying seemed feasible approaches.

  1. FUSE: a profit maximization approach for functional summarization of biological networks.

    Science.gov (United States)

    Seah, Boon-Siew; Bhowmick, Sourav S; Dewey, C Forbes; Yu, Hanry

    2012-03-21

    The availability of large-scale curated protein interaction datasets has given rise to the opportunity to investigate higher level organization and modularity within the protein interaction network (PPI) using graph theoretic analysis. Despite the recent progress, systems level analysis of PPIS remains a daunting task as it is challenging to make sense out of the deluge of high-dimensional interaction data. Specifically, techniques that automatically abstract and summarize PPIS at multiple resolutions to provide high level views of its functional landscape are still lacking. We present a novel data-driven and generic algorithm called FUSE (Functional Summary Generator) that generates functional maps of a PPI at different levels of organization, from broad process-process level interactions to in-depth complex-complex level interactions, through a pro t maximization approach that exploits Minimum Description Length (MDL) principle to maximize information gain of the summary graph while satisfying the level of detail constraint. We evaluate the performance of FUSE on several real-world PPIS. We also compare FUSE to state-of-the-art graph clustering methods with GO term enrichment by constructing the biological process landscape of the PPIS. Using AD network as our case study, we further demonstrate the ability of FUSE to quickly summarize the network and identify many different processes and complexes that regulate it. Finally, we study the higher-order connectivity of the human PPI. By simultaneously evaluating interaction and annotation data, FUSE abstracts higher-order interaction maps by reducing the details of the underlying PPI to form a functional summary graph of interconnected functional clusters. Our results demonstrate its effectiveness and superiority over state-of-the-art graph clustering methods with GO term enrichment.

  2. Dictionary-Based Image Denoising by Fused-Lasso Atom Selection

    Directory of Open Access Journals (Sweden)

    Ao Li

    2014-01-01

    Full Text Available We proposed an efficient image denoising scheme by fused lasso with dictionary learning. The scheme has two important contributions. The first one is that we learned the patch-based adaptive dictionary by principal component analysis (PCA with clustering the image into many subsets, which can better preserve the local geometric structure. The second one is that we coded the patches in each subset by fused lasso with the clustering learned dictionary and proposed an iterative Split Bregman to solve it rapidly. We present the capabilities with several experiments. The results show that the proposed scheme is competitive to some excellent denoising algorithms.

  3. The space station window observational research facility; a high altitude imaging laboratory

    International Nuclear Information System (INIS)

    Runco, Susan K.; Eppler, Dean B.; Scott, Karen P.

    1999-01-01

    Earth Science will be one of the major research areas to be conducted on the International Space Station. The facilities from which this research will be accomplished are currently being constructed and will be described in this paper. By April 1999, the International Space Station nadir viewing research window fabrication will be completed and ready for installation. The window will provide a 20 inch (51 cm) diameter clear aperture. The three fused silica panes, which make up the window are fabricated such that the total peak-to-valley wavefront error in transmission through the three panes over any six inch diameter aperture does not exceed λ/7 where the reference wavelength is 632.8 nm. The window will have over 90% transmission between about 400 and 750, above 50% transmission between about 310 nm and 1375 nm and 40% transmission between 1386 nm and 2000 nm. The Window Operational Research Facility (WORF) is designed to accommodate payloads using this research window. The WORF will provide access to the International Space Station utilities such as data links, temperature cooling loops and power. Emphasis has been placed on the factors which will make this facility an optimum platform for conducting Earth science research

  4. Influence of organic solvents on interfacial water at surfaces of silica gel and partially silylated fumed silica

    International Nuclear Information System (INIS)

    Turov, V.V.; Gun'ko, V.M.; Tsapko, M.D.; Bogatyrev, V.M.; Skubiszewska-Zieba, J.; Leboda, R.; Ryczkowski, J.

    2004-01-01

    The effects of organic solvents (dimethylsulfoxide-d 6 (DMSO-d 6 ), chloroform-d, acetone-d 6 , and acetonitrile-d 3 ) on the properties of interfacial water at surfaces of silica gel Si-40 and partially silylated fumed silica A-380 were studied by means of the 1 H NMR spectroscopy with freezing-out of adsorbed water at 180 1 H NMR investigations were also analysed on the basis of the structural characteristics of silicas and quantum chemical calculations of the chemical shifts δ H and solvent effects. DMSO-d 6 and acetonitrile-d 3 are poorly miscible with water in silica gel pores in contrast to the bulk liquids. DMSO-d 6 and chloroform-d affect the structure of the interfacial water weaker than acetone-d 6 and acetonitrile-d 3 at amounts of liquids greater than the pore volume. Acetone-d 6 and acetonitrile-d 3 can displace water from pores under this condition. The chemical shift of protons in water adsorbed on silica gel is 3.5-6.5 ppm, which corresponds to the formation of two to four hydrogen bonds per molecule. Water adsorbed on partially silylated fumed silica has two 1 H NMR signals at 5 and 1.1-1.7 ppm related to different structures (droplets and small clusters) of the interfacial water

  5. Silica and lung cancer: a controversial issue.

    Science.gov (United States)

    Pairon, J C; Brochard, P; Jaurand, M C; Bignon, J

    1991-06-01

    The role of crystalline silica in lung cancer has long been the subject of controversy. In this article, we review the main experimental and epidemiological studies dealing with this problem. Some evidence for a genotoxic potential of crystalline silica has been obtained in the rare in vitro studies published to date. In vivo studies have shown that crystalline silica is carcinogenic in the rat; the tumour types appear to vary according to the route of administration. In addition, an association between carcinogenic and fibrogenic potency has been observed in various animal species exposed to crystalline silica. An excess of lung cancer related to occupational exposure to crystalline silica is reported in many epidemiological studies, regardless of the presence of silicosis. However, most of these studies are difficult to interpret because they do not correctly take into account associated carcinogens such as tobacco smoke and other occupational carcinogens. An excess of lung cancer is generally reported in studies based on silicosis registers. Overall, experimental and human studies suggest an association between exposure to crystalline silica and an excess of pulmonary malignancies. Although the data available are not sufficient to establish a clear-cut causal relationship in humans, an association between the onset of pneumoconiosis and pulmonary malignancies is probable. In contrast, experimental observations have given rise to a pathophysiological mechanism that might account for a putative carcinogenic potency of crystalline silica.

  6. New Silica Magnetite Sorbent: The Influence of Variations of Sodium Silicate Concentrations on Silica Magnetite Character

    Science.gov (United States)

    Azmiyawati, C.; Pratiwi, P. I.; Darmawan, A.

    2018-04-01

    The adsorption capacity of an adsorbent is determined by the adsorbent and the adsorbate properties. The character of the adsorbent will play a major role in its ability to adsorb the corresponding adsorbate. Therefore, in this study we looked at the effects of variations of sodium silicate concentrations on the resulting magnetite silica adsorbent properties. The application of silica coating on the magnetite was carried out through a sol-gel process with sodium silicate and HCl precursors. Based on the characterization data obtained, it was found that the silica coating on magnetite can increase the resistance to acid leaching, increase the particle size, but decrease the magnetic properties of the magnetite. Based on Gas Sorption Analyzer (GSA) and X-ray Difraction (XRD) data it can successively be determined that increase in concentration of sodium silicate will increase the surface area and amorphous structure of the Silica Magnetie.

  7. Dispersibility of silica fume in mortar and its effect on properties of mortar. Silica fume no bunsan to mortar no shotokusei

    Energy Technology Data Exchange (ETDEWEB)

    Oga, H; Uomoto, T [The University of Tokyo, Tokyo (Japan). Institute of Industrial Science

    1992-08-01

    Effect of silica fume dispersibility on concrete characteristics was discussed. Properties of mortar mixed with silica fume to exhibit compression strength varied with displacement rates, patterns, and mixing time of silica fume. In submerged curing age of 28 days, the compression strength in a mortar mixed with silica fume at 10% was affected only very little by the mixing time for both pelletizing and non-pelletizing types for up to 180 seconds. The strength increased thereafter with the mixing time. The compression strength at 1020 seconds showed higher value by about 150 kgf/cm [sup 2] than when no silica fume is added, with a difference because of patterns disappearing. In the case of a mixing time of 1020 seconds, neutralization depth receives very little effect from a pattern difference, and decreases with increasing displacement rate. Neutralization coefficient of the mortar mixed with silica fume at 10% decreased with the mixing time, and it was possible to suppress the neutralization coefficient to 25% of the case without silica fume addition in a 1020-second mixing. 7 refs., 8 figs., 1 tab.

  8. Effect of different surface treatments and retainer designs on the retention of posterior Pd-Ag porcelain-fused-to-metal resin-bonded fixed partial dentures.

    Science.gov (United States)

    Chen, Xiwen; Zhang, Yixin; Zhou, Jinru; Chen, Chenfeng; Zhu, Zhimin; Li, Lei

    2018-02-01

    The aim of this study was to investigate the adhesive property of palladium-silver alloy (Pd-Ag) and the simulated clinical performance of Pd-Ag porcelain-fused-to-metal (PFM), resin-bonded, fixed partial dentures (RBFPDs). A total of 40 Pd-Ag discs (diameter=5 mm) were prepared and divided into the following four groups (n=10): a) No sandblasting, used as a control; and b, 50 µm; c, 110 µm; and d, 250 µm aluminum oxide (Al 2 O 3 ) particles, respectively. Another 50 discs were pre-sandblasted and divided into five groups (n=10) subjected to different treatments: e) Sandblasting, used as a control; f) silane; g) alloy primer; h) silica coating + silane and i) silica coating + alloy primer. All 90 discs were bonded to enamel with Panavia F 2.0 and then subjected to shear bond strength (SBS) testing. The fracture surfaces were examined by scanning electron microscopy. Next, 40 missing maxillary second premolar models were restored with one of the four following RBFPD designs (n=10): I) A premolar occlusal bar combined with molar double rests (MDR); II) both occlusal bars with a wing (OBB); III) a premolar occlusal bar combined with a molar dental band (MDB); and IV) two single rests adjacent to the edentulous space with a wing (SRB) used as a control. All specimens were aged with thermal cycling and mechanical loading. Subsequently, they were loaded until broken. The data were analyzed by one-way analysis of variance. Al 2 O 3 (250 µm) abrasion provided the highest SBS (P<0.05). The alloy primer and silica + silane exhibited increased SBS. Furthermore, fracture analysis revealed that the failure mode varied among the different treatments. Whereas MDB exhibited the highest retention (P<0.05), that of OBB was greater than that of MDR (P<0.05), and the control exhibited the lowest retention. Abrasion with Al 2 O 3 (250 µm) effectively increased the adhesive property of Pd-Ag. Additionally, treatment with the alloy primer and silica coating + silane was able to

  9. Synthesis of Silica Nanoparticles by Sol-Gel: Size-Dependent Properties, Surface Modification, and Applications in Silica-Polymer Nano composites-A Review

    International Nuclear Information System (INIS)

    Ismail, A.R.; Vejayakumaran, P.

    2012-01-01

    Application of silica nanoparticles as fillers in the preparation of nano composite of polymers has drawn much attention, due to the increased demand for new materials with improved thermal, mechanical, physical, and chemical properties. Recent developments in the synthesis of monodispersed, narrow-size distribution of nanoparticles by sol-gel method provide significant boost to development of silica-polymer nano composites. This paper is written by emphasizing on the synthesis of silica nanoparticles, characterization on size-dependent properties, and surface modification for the preparation of homogeneous nano composites, generally by sol-gel technique. The effect of nano silica on the properties of various types of silica-polymer composites is also summarized.

  10. Overcurrent protection of transformers. Part 2: Traditional and new fusing philosophies for small and large transformers

    Energy Technology Data Exchange (ETDEWEB)

    Cook, C. J.; Niemira, J. K.

    2003-07-01

    New and traditional fusing philosophies for protecting transformers are discussed. This second in a two-part paper covers selection criteria for a transformer-primary fuse to protect the transformer consistent with industry-accepted through-fault protection curves. Also covered are the principles of coordination as they relate to the proper selection of the primary-side fuse and power fuses and the principles underlying the protection of load-side conductors and cables. The critical nature of secondary fault protection on small three-phase transformers used on industrial, commercial, and institutional power systems, as well as small-to-medium size three-phase power transformers used in utility substations is emphasized, in view of the long lead time and expense involved in replacing these transformers. In contrast, no special protection recommendations are made for small-kVA overhead distribution transformers, since they are not considered likely to experience secondary faults, and the rare faults that do occur will not likely be detected and cleared by the primary fuse. Also of importance is the fact that these transformers are inexpensive and readily available. Overall, large fuse rating, used in combination with a tank-mounted surge arrester is recommended, because it can provide better transformer protection than the smaller fuse ratings traditionally employed. 4 refs., 2 tabs., 4 figs.

  11. Silica sol as grouting material: a physio-chemical analysis.

    Science.gov (United States)

    Sögaard, Christian; Funehag, Johan; Abbas, Zareen

    2018-01-01

    At present there is a pressing need to find an environmentally friendly grouting material for the construction of tunnels. Silica nanoparticles hold great potential of replacing the organic molecule based grouting materials currently used for this purpose. Chemically, silica nanoparticles are similar to natural silicates which are essential components of rocks and soil. Moreover, suspensions of silica nanoparticles of different sizes and desired reactivity are commercially available. However, the use of silica nanoparticles as grouting material is at an early stage of its technological development. There are some critical parameters such as long term stability and functionality of grouted silica that need to be investigated in detail before silica nanoparticles can be considered as a reliable grouting material. In this review article we present the state of the art regarding the chemical properties of silica nanoparticles commercially available, as well as experience gained from the use of silica as grouting material. We give a detailed description of the mechanisms underlying the gelling of silica by different salt solutions such as NaCl and KCl and how factors such as particle size, pH, and temperature affect the gelling and gel strength development. Our focus in this review is on linking the chemical properties of silica nanoparticles to the mechanical properties to better understand their functionality and stability as grouting material. Along the way we point out areas which need further research.

  12. Preparation of thick silica coatings on carbon fibers with fine-structured silica nanotubes induced by a self-assembly process

    Directory of Open Access Journals (Sweden)

    Benjamin Baumgärtner

    2017-05-01

    Full Text Available A facile method to coat carbon fibers with a silica shell is presented in this work. By immobilizing linear polyamines on the carbon fiber surface, the high catalytic activity of polyamines in the sol–gel-processing of silica precursors is used to deposit a silica coating directly on the fiber’s surface. The surface localization of the catalyst is achieved either by attaching short-chain polyamines (e.g., tetraethylenepentamine via covalent bonds to the carbon fiber surface or by depositing long-chain polyamines (e.g., linear poly(ethylenimine on the carbon fiber by weak non-covalent bonding. The long-chain polyamine self-assembles onto the carbon fiber substrate in the form of nanoscopic crystallites, which serve as a template for the subsequent silica deposition. The silicification at close to neutral pH is spatially restricted to the localized polyamine and consequently to the fiber surface. In case of the linear poly(ethylenimine, silica shells of several micrometers in thickness can be obtained and their morphology is easily controlled by a considerable number of synthesis parameters. A unique feature is the hierarchical biomimetic structure of the silica coating which surrounds the embedded carbon fiber by fibrillar and interconnected silica fine-structures. The high surface area of the nanostructured composite fiber may be exploited for catalytic applications and adsorption purposes.

  13. Investigation of novel fractal shape of the nano-aperture as a metasurface for bio sensing application

    Energy Technology Data Exchange (ETDEWEB)

    Heydari, Samaneh [Sama Technical and Vocational Training College, Islamic Azad University, Isfahan Branch, Khorasgan (Iran, Islamic Republic of); Rastan, Iman; Parvin, Amin [Faculty of Eng., Science and Research Branch, Islamic Azad University, Shiraz (Iran, Islamic Republic of); Pirooj, Azadeh [Faculty of Eng., Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Zarrabi, Ferdows B., E-mail: ferdows.zarrabi@yahoo.com [Young Researchers and Elite Club, Babol Branch, Islamic Azad University, Babol (Iran, Islamic Republic of)

    2017-01-23

    Recently, nano-aperture is noticed due to its good transmission in the optical regime. Also, the nano-apertures are developed at the metasurface design for circular polarization; for this aim, various shapes of the nano-aperture are suggested. To reach this objective, we have developed a novel Jerusalem cross fractal shape for a mid-infrared application. We have simulated various formations of the nano-fractal Jerusalem cross based on a simple cross to show the effect of nano-aperture shape on electrical field enhancement in the near-field which is important in spectroscopy and optical imaging. In addition, we have used a single layer graphene over the aperture as a coat for making reconfigurable characteristic also creating a membrane for placement of nano-particle over the aperture. Implementation of the graphene is an amendment to the transfer of the nano-apertures. The biological materials with a thickness of 80 nm have been placed over the graphene layer and the Figures of Merits (FOM) have been obtained. Additionally, the prototype of nano-antenna is independent from incident wave polarization. The Finite Difference Time Domain (FDTD) calculations have been implemented in the simulation and modeling the nano-apertures. - Highlights: • Nano-apertures are developed at the metasurface design for circular polarization. • We have developed a novel Jerusalem cross fractal shape for a mid-infrared application. • Effect of nano-aperture shape on near-field enhancement is noticed which is important in spectroscopy and optical imaging. • Single layer graphene over the aperture as a coat for making reconfigurable characteristic.

  14. Ordered nanoporous silica as carriers for improved delivery of water insoluble drugs: a comparative study between three dimensional and two dimensional macroporous silica

    Directory of Open Access Journals (Sweden)

    Wang Y

    2013-10-01

    Full Text Available Ying Wang, Qinfu Zhao, Yanchen Hu, Lizhang Sun, Ling Bai, Tongying Jiang, Siling WangDepartment of Pharmaceutics, Shenyang Pharmaceutical University, Liaoning Province, People’s Republic of ChinaAbstract: The goal of the present study was to compare the drug release properties and stability of the nanoporous silica with different pore architectures as a matrix for improved delivery of poorly soluble drugs. For this purpose, three dimensional ordered macroporous (3DOM silica with 3D continuous and interconnected macropores of different sizes (200 nm and 500 nm and classic mesoporous silica (ie, Mobil Composition of Matter [MCM]-41 and Santa Barbara Amorphous [SBA]-15 with well-ordered two dimensional (2D cylindrical mesopores were successfully fabricated and then loaded with the model drug indomethacin (IMC via the solvent deposition method. Scanning electron microscopy (SEM, N2 adsorption, differential scanning calorimetry (DSC, and X-ray diffraction (XRD were applied to systematically characterize all IMC-loaded nanoporous silica formulations, evidencing the successful inclusion of IMC into nanopores, the reduced crystallinity, and finally accelerated dissolution of IMC. It was worth mentioning that, in comparison to 2D mesoporous silica, 3DOM silica displayed a more rapid release profile, which may be ascribed to the 3D interconnected pore networks and the highly accessible surface areas. The results obtained from the stability test indicated that the amorphous state of IMC entrapped in the 2D mesoporous silica (SBA-15 and MCM-41 has a better physical stability than in that of 3DOM silica. Moreover, the dissolution rate and stability of IMC loaded in 3DOM silica was closely related to the pore size of macroporous silica. The colorimetric 3-(4,5-Dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide (MTT and Cell Counting Kit (CCK-8 assays in combination with direct morphology observations demonstrated the good biocompatibility of nanoporous

  15. Crossed fused renal ectopia in a Persian cat

    Directory of Open Access Journals (Sweden)

    Sang-Hyuk Seo

    2017-03-01

    Full Text Available Case summary This report describes a rare case of crossed fused renal ectopia (CFRE in a cat. A mature intact male Persian cat presented with bloody nasal discharge and ascites. Diagnostic studies revealed an ectopic left kidney fused with an orthotopic right kidney and a concurrent feline infectious peritonitis (FIP infection. The FIP was responsible for clinical signs in this cat, while clinical signs associated with CFRE were not obvious. Despite receiving intensive treatment, the cat died. A post-mortem examination was not performed because the owners declined approval. Relevance and novel information To the best of our knowledge, this is the first report of L-shaped CFRE in a cat. In addition, this report describes the CT features of L-shaped CFRE in a cat.

  16. Multi-kW single fiber laser based on an extra large mode area fiber design

    Science.gov (United States)

    Langner, Andreas; Such, Mario; Schötz, Gerhard; Just, Florian; Leich, Martin; Schwuchow, Anka; Grimm, Stephan; Zimer, Hagen; Kozak, Marcin; Wedel, Björn; Rehmann, Georg; Bachert, Charley; Krause, Volker

    2012-02-01

    The quality of Yb-doped fused bulk silica produced by sintering of Yb-doped fused silica granulates has improved greatly in the past five years [1 - 4]. In particular, the refractive index and doping level homogeneity of such materials are excellent and we achieved excellent background fiber attenuation of the active core material down to about 20 dB/km at 1200 nm. The improvement of the Yb-doped fused bulk silica has enabled the development of multi-kW fiber laser systems based on a single extra large multimode laser fiber (XLMA fiber). When a single active fiber is used in combination with the XLMA multimode fiber of 1200 μm diameter simple and robust high power fiber laser setups without complex fiber coupling and fiber combiner systems become possible. In this papper, we will discuss in detail the development of the core material based on Yb-doped bulk silica and the characterization of Yb-doped fibers with different core compositions. We will also report on the excellent performance of a 4 kW fiber laser based on a single XLMA-fiber and show the first experimental welding results of steel sheets achieved with such a laser.

  17. Diagnosis and staging of breast cancer by SPECT images fused with CT images

    International Nuclear Information System (INIS)

    Li Yanjing; Zhu Qiaomei

    2007-01-01

    Objective: To evaluate the TNM staging value of 99mTc-MIBI scintimammotraphy with SPECT-CT images fusing for the diagnosis of breast cancer. Methods: 10 patients with breast cancer underwent scintimammography with 99mTc-MIBI, and SPECT images were fused with CT images. Images were compared with final diagnosis confirmed by histopathology. Results: Of the 19 breast cancer patients, one case of invasive ductal carcinoma showed false-negative. Among 18 cases of positive lesions, axillary metastases were involved in 10, supraclavicular nodes were also defined in 3, para-sternum nodes were involved in 2, 2 were missed and 1 cases without metastatic node. The axillary lymph nodes were divided into three levels with respect to their position relative to the pectoralis minor muscle by fused images. Conclusion: 99mTc-MIBI scintimammotraphy combined with SPECT-CT images fusing is of some clinical value in TNM staging of breast cancer. (authors)

  18. Measurement and modelization of silica opal optical properties

    OpenAIRE

    Avoine , Amaury; Ngoc Hong , Phan; Frederich , Hugo; Aregahegn , Kifle; Bénalloul , Paul; Coolen , Laurent; Schwob , Catherine; Thu Nga , Pham; Gallas , Bruno; Maître , Agnès

    2014-01-01

    International audience; We present the synthesis process and optical characterization of artificial silica opals. The specular reflection spectra are analyzed and compared to band structure calculations and finite difference time domain (FDTD) simulations. The silica optical index is a key parameter to correctly describe an opal and is usually not known and treated as a free parameter. Here we propose a method to infer the silica index, as well as the silica spheres diameter, from the reflect...

  19. Functionalized mesoporous silica materials for molsidomine adsorption: Thermodynamic study

    International Nuclear Information System (INIS)

    Alyoshina, Nonna A.; Parfenyuk, Elena V.

    2013-01-01

    A series of unmodified and organically modified mesoporous silica materials was prepared. The unmodified mesoporous silica was synthesized via sol–gel synthesis in the presence of D-glucose as pore-forming agent. The functionalized by phenyl, aminopropyl and mercaptopropyl groups silica materials were prepared via grafting. The fabricated adsorbent materials were characterized by Fourier transform infrared spectroscopy (FTIR) analysis, N 2 adsorption/desorption and elemental analysis methods. Then their adsorption properties for mesoionic dug molsidomine were investigated at 290–313 K and physiological pH value. Thermodynamic parameters of molsidomine adsorption on the synthesized materials have been calculated. The obtained results showed that the adsorption process of molsidomine on the phenyl modified silica is the most quantitatively and energetically favorable. The unmodified and mercaptopropyl modified silica materials exhibit significantly higher adsorption capacities and energies for molsidomine than the aminopropyl modified sample. The effects are discussed from the viewpoint of nature of specific interactions responsible for the adsorption. - Graphical abstract: Comparative analysis of the thermodynamic characteristics of molsidomine adsorption showed that the adsorption process on mesoporous silica materials is controlled by chemical nature of surface functional groups. Molsidomine adsorption on the phenyl modified silica is the most quantitatively and energetically favorable. Taking into account ambiguous nature of mesoionic compounds, it was found that molsidomine is rather aromatic than dipolar. Display Omitted - Highlights: • Unmodified and organically modified mesoporous silica materials were prepared. • Molsidomine adsorption on the silica materials was studied. • Phenyl modified silica shows the highest adsorption capacity and favorable energy. • Molsidomine exhibits the lowest affinity to aminopropyl modified silica

  20. Dendritic cells fused with different pancreatic carcinoma cells induce different T-cell responses

    Directory of Open Access Journals (Sweden)

    Andoh Y

    2013-01-01

    Full Text Available Yoshiaki Andoh,1,2 Naohiko Makino,2 Mitsunori Yamakawa11Department of Pathological Diagnostics, 2Department of Gastroenterology, Yamagata University School of Medicine, Yamagata, JapanBackground: It is unclear whether there are any differences in the induction of cytotoxic T lymphocytes (CTL and CD4+CD25high regulatory T-cells (Tregs among dendritic cells (DCs fused with different pancreatic carcinomas. The aim of this study was to compare the ability to induce cytotoxicity by human DCs fused with different human pancreatic carcinoma cell lines and to elucidate the causes of variable cytotoxicity among cell lines.Methods: Monocyte-derived DCs, which were generated from peripheral blood mononuclear cells (PBMCs, were fused with carcinoma cells such as Panc-1, KP-1NL, QGP-1, and KP-3L. The induction of CTL and Tregs, and cytokine profile of PBMCs stimulated by fused DCs were evaluated.Results: The cytotoxicity against tumor targets induced by PBMCs cocultured with DCs fused with QGP-1 (DC/QGP-1 was very low, even though PBMCs cocultured with DCs fused with other cell lines induced significant cytotoxicity against the respective tumor target. The factors causing this low cytotoxicity were subsequently investigated. DC/QGP-1 induced a significant expansion of Tregs in cocultured PBMCs compared with DC/KP-3L. The level of interleukin-10 secreted in the supernatants of PBMCs cocultured with DC/QGP-1 was increased significantly compared with that in DC/KP-3L. Downregulation of major histocompatibility complex class I expression and increased secretion of vascular endothelial growth factor were observed with QGP-1, as well as in the other cell lines.Conclusion: The present study demonstrated that the cytotoxicity induced by DCs fused with pancreatic cancer cell lines was different between each cell line, and that the reduced cytotoxicity of DC/QGP-1 might be related to the increased secretion of interleukin-10 and the extensive induction of Tregs