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Sample records for cerium-doped silica fibres

  1. Sulphur-doped silica fibres

    SciTech Connect

    Gerasimova, V I; Rybaltovskii, A O; Chernov, P V; Mashinsky, V M; Sazhin, O D; Medvedkov, O I; Rybaltovsky, A A; Khrapko, R R

    2003-01-31

    An optical fibre with low optical losses is manufactured from a sulphur-doped quartz glass. Optical absorption spectra are measured for various parts of the fibre core. Most of the bands of these spectra are assigned to oxygen-deficient centres and colour centres containing sulphur atoms. The photosensitivity of glasses exposed to laser radiation at wavelengths of 193 and 244 nm is investigated to estimate the possibility of their application for producing photorefracting devices. A Bragg grating of the refractive index with {Delta}n = 7.8 x 10{sup -4} is written in a sulphur-doped silica fibre. (fibre optics)

  2. Progress in reliability of silica optical fibres

    NASA Astrophysics Data System (ADS)

    Severin, Irina; Poulain, M.; El Abdi, R.

    2008-04-01

    Silica optical fibres that were developed for telecommunication networks extend their use for sensors and smart structures. Their reliability and expected lifetime has appeared as a major concern. Series of experiments were implemented in order to assess fibre behaviour in different environmental conditions, including chemical corrosion and mechanical stress. Optical fibres were aged in water under controlled stress overlapping microwave energy for different durations. Fibre samples were wound on different diameter mandrels applying consequently a non-uniform tensile, respectively compression stress in function of the fibre's section. Different experimental combinations were implemented in order to separate aging factor effects. Then, these aged / stretched fibres were dynamic tensile tested at different strain rates and results were statistically treated using Weibull theory. In certain cases and testing conditions, comparison with as received fibres has revealed strength increase with a generally mono-modal defect distribution on the fibre surface. Base on previous and current results, the structural relaxation phenomenon at the silica cladding - polymer coating interface might be evidenced.

  3. Optical Response of Shocked Cerium-Doped Lutetium Oxyorthosilicate

    SciTech Connect

    G. D. Stevens

    2003-03-01

    Shock experiments were performed in order to characterize the triboluminescent signature of cerium-doped lutetium oxyorthosilicate (LSO:Ce). This material shows prompt, nano-second timescale light emission when driven by explosive detonation. When properly applied to a surface, it may be used as a shock arrival sensor, and also for imaging the propagation of a shock front. Triboluminescent rise times, spectral content, and spatial resolution measurements are presented.

  4. Optical properties of active bismuth centres in silica fibres containing no other dopants

    SciTech Connect

    Bufetov, Igor' A; Semenov, S L; Vel'miskin, V V; Firstov, Sergei V; Dianov, Evgenii M; Bufetova, G A

    2010-09-10

    Optical fibre preforms and fibres with a bismuth-doped silica core containing no other dopants have been fabricated by the powder-in-tube technique. The optical loss has been measured for the first time in such fibres in a wide spectral range, from 190 to 1700 nm. We have studied the luminescence of active bismuth centres and the luminescence lifetime for some of their bands in both the preforms and the fibres drawn out from them. (optical fibres)

  5. Photonic bandgap single-mode optical fibre with ytterbium-doped silica glass core

    SciTech Connect

    Egorova, O N; Semenov, S L; Vel'miskin, V V; Dianov, Evgenii M; Salganskii, M Yu; Yashkov, M V; Gur'yanov, Aleksei N

    2011-01-24

    A photonic bandgap fibre with an ytterbium-doped silica glass core is fabricated and investigated. The possibility of implementing single-mode operation of such fibres in a wide spectral range at a large (above 20 {mu}m) mode field diameter makes them promising for fibre lasers and amplifiers. To ensure a high quality of the beam emerging from the fibre, particular attention is paid to increasing the optical homogeneity of the ytterbium-doped core glass. (optical fibres)

  6. Feasibility of constructing a UV fibre laser based on a nitrogen-doped silica optical fibre

    SciTech Connect

    Bufetov, Igor' A; Grekov, M V; Golant, K M; Dianov, Evgenii M; Khrapko, R R

    1998-04-30

    Nonlinear frequency conversion of neodymium laser ({lambda}= 1.06 {mu}m) radiation was observed when this radiation was injected into the core of a single-mode optical fibre made of nitrogen-doped silica. This resulted in generation of visible violet and near-ultraviolet radiation (355 - 430 nm). The conversion efficiency was up to 2 x 10{sup -4}. The observed UV radiation was the result of the following processes: generation of the third harmonic of the fundamental pump frequency, stimulated Raman scattering of the third harmonic, and generation of the third harmonics of the Raman-scattered components of the pump radiation. Lasing was also observed in the 380-430 nm wavelength range at colour centres associated with the presence of nitrogen in the silica core. (nonlinear optical phenomena and devices)

  7. The polymer converter for effectively connecting polymer with silica optical fibres

    NASA Astrophysics Data System (ADS)

    Pura-Pawlikowska, P.; Dudek, M.; Wonko, R.; Marć, P.; Kujawińska, M.; Jaroszewicz, L. R.

    2016-09-01

    We present a micrometer-size polymer converter (microbridge) for connecting polymer optical fibres with silica fibres. The procedure of preparing such microstructure is based on a process of photopolymerization. A polymer converter grows as an extension of the fibres' cores due to a self-guiding effect of the light beam in a photopolymerizable medium. Since the polymer microbridge has refractive index greater inside than outside, such a structure works as a waveguide leading the light beam between connected optical fibres. By selection of time of light exposition to the mixture and optical power of the incident light beam, it is possible to obtain a polymer converter with very good optical and mechanical characteristics. Possibility of using polymer microbridges grown directly from the fibres' core as coupling elements between silica and polymer fibres is a good alternative for obtaining permanent coupling of such fibres.

  8. Micromechanical modelling of oil palm empty fruit bunch fibres containing silica bodies.

    PubMed

    Omar, Farah Nadia; Hanipah, Suhaiza Hanim; Xiang, Loo Yu; Mohammed, Mohd Afandi P; Baharuddin, Azhari Samsu; Abdullah, Jaafar

    2016-09-01

    Experimental and numerical investigation was conducted to study the micromechanics of oil palm empty fruit bunch fibres containing silica bodies. The finite viscoelastic-plastic material model called Parallel Rheological Network model was proposed, that fitted well with cyclic and stress relaxation tensile tests of the fibres. Representative volume element and microstructure models were developed using finite element method, where the models information was obtained from microscopy and X-ray micro-tomography analyses. Simulation results showed that difference of the fibres model with silica bodies and those without ones is larger under shear than compression and tension. However, in comparison to geometrical effect (i.e. silica bodies), it is suggested that ultrastructure components of the fibres (modelled using finite viscoelastic-plastic model) is responsible for the complex mechanical behaviour of oil palm fibres. This can be due to cellulose, hemicellulose and lignin components and the interface behaviour, as reported on other lignocellulosic materials. PMID:27183430

  9. Optical properties of IR-emitting centres in Pb-doped silica fibres

    SciTech Connect

    Zlenko, Alexander S; Firstov, Sergei V; Ryumkin, K E; Khopin, V F; Iskhakova, L D; Semenov, S L; Bufetov, Igor' A; Dianov, Evgenii M

    2012-04-30

    The first fibre preforms with a Pb-doped silica core, free of other dopants, have been produced using chemical vapour deposition. The preforms have been used to fabricate holey optical fibres. The spectroscopic properties of the fibres have been studied in detail in the range 400 - 1700 nm: we have measured the optical loss, constructed a three-dimensional luminescence excitation - emission graph and determined the decay time for the major luminescence peaks.

  10. Radiation-resistant erbium-doped silica fibre

    SciTech Connect

    Zotov, K V; Likhachev, M E; Tomashuk, A L; Bubnov, M M; Yashkov, M V; Gur'yanov, A N

    2007-10-31

    It is shown that the service life of erbium-doped fibres can be increased many times under conditions of an elevated radiation level by loading the fibre glass network with molecular hydrogen. Backdiffusion of hydrogen from the fibre in the process of its operation is virtually excluded for the fibre covered with a hermetic carbon coating. It is shown that this technique of fibre preparation allows one to slow down significantly degradation of the lasing properties of erbium fibres under the conditions characteristic of space applications. (special issue devoted to the 25th anniversary of the a.m. prokhorov general physics institute)

  11. Fabrication of silica hollow core photonic crystal fibres for Er:YAG surgical applications

    NASA Astrophysics Data System (ADS)

    Urich, Artur; Maier, Robert R. J.; Knight, Jonathan C.; Mangan, Brian J.; Renshaw, Steven; Hand, Duncan P.; Shephard, Jonathan D.

    2012-01-01

    In this work we present the fabrication of silica hollow core photonic crystal fibres (HC-PCF) with guidance at 2.94μm. As light is confined inside the hollow core with a very small overlap of the guided E-M wave with the fibre material, the high intrinsic loss of silica at these mid-infrared wavelengths can be overcome. The band gap effect is achieved by a periodic structure made out of air and fused silica. As silica is bio-inert, chemically stable and mechanically robust, these fibres have potential advantages over other multi-component, non-silica optical fibres designed to guide in this wavelength regime. These fibres have a relatively small diameter, low bend sensitivity and single-mode like guidance which are ideal conditions for delivering laser light down a highly flexible fibre. Consequently they provide a potential alternative to existing surgical laser delivery methods such as articulated arms and lend themselves to endoscopy and other minimally invasive surgical procedures. In particular, we present the characterisation and performance of these fibres at 2.94 μm, the wavelength of an Er:YAG laser. This laser is widely used in surgery since the wavelength overlaps with an absorption band of water which results in clean, non-cauterised cuts. However, the practical implementation of these types of fibres for surgical applications is a significant challenge. Therefore we also report on progress made in developing hermetically sealed end tips for these hollow core fibres to avoid contamination. This work ultimately prepares the route towards a robust, practical delivery system for this wavelength.

  12. Optical properties of bismuth-doped silica fibres in the temperature range 300 - 1500 K

    SciTech Connect

    Dvoretskii, D A; Bufetov, Igor' A; Vel'miskin, V V; Zlenko, Alexander S; Khopin, V F; Semjonov, S L; Guryanov, Aleksei N; Denisov, L K; Dianov, Evgenii M

    2012-09-30

    The visible and near-IR absorption and luminescence bands of bismuth-doped silica and germanosilicate fibres have been measured for the first time as a function of temperature. The temperature-dependent IR luminescence lifetime of a bismuth-related active centre associated with silicon in the germanosilicate fibre has been determined. The Bi{sup 3+} profile across the silica fibre preform is shown to differ markedly from the distribution of IR-emitting bismuth centres associated with silicon. The present results strongly suggest that the IR-emitting bismuth centre comprises a lowvalence bismuth ion and an oxygen-deficient glass network defect. (optical fibres, lasers and amplifiers. properties and applications)

  13. High power operation of cladding pumped holmium-doped silica fibre lasers.

    PubMed

    Hemming, Alexander; Bennetts, Shayne; Simakov, Nikita; Davidson, Alan; Haub, John; Carter, Adrian

    2013-02-25

    We report the highest power operation of a resonantly cladding-pumped, holmium-doped silica fibre laser. The cladding pumped all-glass fibre utilises a fluorine doped glass layer to provide low loss cladding guidance of the 1.95 µm pump radiation. The operation of both single mode and large-mode area fibre lasers was demonstrated, with up to 140 W of output power achieved. A slope efficiency of 59% versus launched pump power was demonstrated. The free running emission was measured to be 2.12-2.15 µm demonstrating the potential of this architecture to address the long wavelength operation of silica based fibre lasers with high efficiency. PMID:23481989

  14. Studies of Some Cerium Doped Strontium Stannate Synthesized by Solid State Route

    SciTech Connect

    Kurre, Rakesh; Bajpai, P. K.

    2011-11-22

    Cerium doped ceramic compositions SrSn{sub 1-x}Ce{sub x}O{sub 3} (x = 0.00 ,0.01, 0.02, 0.04) have been synthesized by solid state reaction route and structurally characterized using x-ray diffraction. X-ray diffraction confirms the formation of single phase compositions having orthorhombic perovskite structure for all compositions. The lattice parameters change with cerium doping. Percentage experimental density decreases from 87.9% in undoped composition to 72.6%, 70.6%, 66.5% respectively with increase in cerium doping indicating that cerium is going to Sr site. The temperature dependent dielectric behavior shows low frequency dielectric dispersion at higher temperature and a weak dielectric anomaly emerging in the temperature range around 250 deg. C. D.C. and A.C. electrical conductivity variation with temperature and frequency show that the d.c. conductivity of the sample in lower temperature region is few orders of magnitude less than the a.c. conductivity and its variation with temperature is also different. The activation energy barriers for a.c. and d.c. conduction is also different.

  15. Fabrication and characterization of cerium-doped barium titanate inverse opal by sol-gel method

    SciTech Connect

    Jin Yi; Zhu Yihua Yang Xiaoling; Li Chunzhong; Zhou Jinghong

    2007-01-15

    Cerium-doped barium titanate inverted opal was synthesized from barium acetate contained cerous acetate and tetrabutyl titanate in the interstitial spaces of a polystyrene (PS) opal. This procedure involves infiltration of precursors into the interstices of the PS opal template followed by hydrolytic polycondensation of the precursors to amorphous barium titanate and removal of the PS opal by calcination. The morphologies of opal and inverse opal were characterized by scanning electron microscope (SEM). The pores were characterized by mercury intrusion porosimetry (MIP). X-ray photoelectron spectroscopy (XPS) investigation showed the doping structure of cerium, barium and titanium. And powder X-ray diffraction allows one to observe the influence of doping degree on the grain size. The lattice parameters, crystal size and lattice strain were calculated by the Rietveld refinement method. The synthesis of cerium-doped barium titanate inverted opals provides an opportunity to electrically and optically engineer the photonic band structure and the possibility of developing tunable three-dimensional photonic crystal devices. - Graphical abstract: Cerium-doped barium titanate inverted opal was synthesized from barium acetate acid contained cerous acetate and tetrabutyl titanate in the interstitial spaces of a PS opal, which involves infiltration of precursors into the interstices of the PS opal template and removal of the PS opal by calcination.

  16. Gamma radiation-induced blue shift of resonance peaks of Bragg gratings in pure silica fibres

    NASA Astrophysics Data System (ADS)

    Faustov, A. V.; Gusarov, A. I.; Mégret, P.; Wuilpart, M.; Kinet, D.; Zhukov, A. V.; Novikov, S. G.; Svetukhin, V. V.; Fotiadi, A. A.

    2016-02-01

    We report the first observation of a significant gamma radiation-induced blue shift of the reflection/transmission peak of fibre Bragg gratings inscribed into pure-silica core fibres via multiphoton absorption of femtosecond pulses. At a total dose of ~100 kGy, the shift is ~20 pm. The observed effect is attributable to the ionising radiation-induced decrease in the density of the silica glass when the rate of colour centre formation is slow. We present results of experimental measurements that provide the key parameters of the dynamics of the gratings for remote dosimetry and temperature sensing.

  17. Angular distribution of light scattered from heavily doped silica fibres

    SciTech Connect

    Alekseev, V V; Likhachev, M E; Bubnov, M M; Salganskii, M Yu; Khopin, V F; Gur'yanov, Aleksei N; Dianov, Evgenii M

    2011-10-31

    This paper describes an experimental setup for precision measurements of the angular distribution of light scattered by optical fibres in a wide angular range and demonstrates that the models of anomalous scattering proposed to date need to be refined. We have found and interpreted a discrepancy between the Rayleigh scattering coefficients measured by different techniques.

  18. Synthesis and photocatalytic activity of mesoporous cerium doped TiO{sub 2} as visible light sensitive photocatalyst

    SciTech Connect

    Aman, Noor; Satapathy, P.K.; Mishra, T.; Mahato, M.; Das, N.N.

    2012-02-15

    Graphical abstract: Cerium doped titania having optimum 5 wt% of cerium can decompose methylene blue and reduce selenium (IV) efficiently under visible light. Highlights: Black-Right-Pointing-Pointer Effect of cerium doping on the surface properties and visible light mediated photocatalytic reaction is studied. Black-Right-Pointing-Pointer Cerium doping increases the anatase phase stability, surface area (up to 137 m{sup 2}/g) and visible light absorption. Black-Right-Pointing-Pointer Importance of Ce{sup 3+}/Ce{sup 4+}, oxygen vacancy, surface area and crystallinity is correlated with improved catalytic activity. Black-Right-Pointing-Pointer Material with 5 wt% Ce is found to be most active photocatalyst for methylene blue decomposition and Se (IV) reduction. -- Abstract: Cerium doped titania materials were synthesized varying the cerium concentration from 0 to 10 wt%. Materials are characterised by XRD, TEM, XPS and N{sub 2} adsorption desorption method. Surface area and visible light absorption substantially increases and crystallite size decreases with the increasing cerium content. Cerium doping stabilizes the anatase phase and surface area even at 600 Degree-Sign C calcination. Photocatalytic activity towards methylene blue decomposition and selenium (IV) reduction is found to increase with the cerium content up to 5 wt% and then decreases. Materials calcined at 600 Degree-Sign C shows better activity than that calcined at 400 Degree-Sign C, even though surface area decreases. Anatase crystallinity mostly decides the photocatalytic activity rather than only surface area. It can be concluded that the optimum visible light absorption and oxygen vacancy with 5% cerium doping enhances the photocatalytic activity. In addition photocatalytic performance is found to depend on the presence of Ce{sup 4+}/Ce{sup 3+} rather than only visible light absorption.

  19. Damping and tuning of the fibre violin modes in monolithic silica suspensions

    NASA Astrophysics Data System (ADS)

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

    2004-03-01

    High Q mirror suspensions are a key element of the advanced interferometric gravitational-wave detectors. In December 2002 the last of the final interferometer optics of GEO 600 were monolithically suspended, using fused silica fibres. The violin modes of the suspension fibres can have Q greater than 108 and can therefore interfere with the interferometer length control servo. Hence, the violin modes need to be damped, without degrading the pendulum Q itself. Furthermore, the frequency spread of the fibres used has to be small to allow for high Q notch filtering in the length control servo. The requirements for the violin modes of the two GEO 600 inboard suspensions are Q < 3 × 106 for the fundamental and Q < 2 × 106 for the first harmonic mode, respectively. The frequency spread should not exceed 10% within one mode. To accomplish that, two sections of the fibres were coated with amorphous Teflon. By applying the coating, the Q of the relevant modes can be degraded to the desired values and furthermore, the frequencies of these modes can be tuned almost independently with a good accuracy over a wide range. After welding the fibres in the monolithic suspension, a corrective coating was applied to some fibres, to compensate for the frequency spread due to the tension spread of the four fibres within a suspension. We present the method and the results achieved.

  20. Structural, topographical and electrical properties of cerium doped strontium barium niobate (Ce:SBN60) ceramics

    NASA Astrophysics Data System (ADS)

    Raj, S. Gokul; Mathivanan, V.; Kumar, G. Ramesh; Yathavan, S.; Mohan, R.

    2016-05-01

    Tungsten bronze type cerium doped strontium barium niobate (Ce:SBN - Sr0.6B0.4Nb2O6) ceramics were synthesized by solid state process. Cerium was used as dopant to improve its electrical properties. Influence of Ce+ ions on the photoluminescence properties was investigated in detail. The grain size topographical behavior of SBN powders and their associated abnormal grain growth (AGG) were completely analyzed through SEM studies. Finally dielectric, measurement discusses about the broad phase transition observed due to cerium dopant The results were discussed in detail.

  1. Photonic bandgap guiding into a composite AgPO3-glass/silica microstructured optical fibre

    NASA Astrophysics Data System (ADS)

    Konidakis, Ioannis; Zito, Gianluigi; Pissadakis, Stavros

    2012-04-01

    Infiltration of glass matrices inside Photonic Crystals Fibres (PCFs) for achieving photonic bandgap (PBG) guidance and expand devices development capabilities has been recently demonstrated. Herein, we report the fabrication of an all-solid PBG guiding PCF by suction-assisted infiltration of molten silver-metaphosphate (AgPO3) glass into the air capillaries of a commercial solid core PCF. The relatively low viscosity of the AgPO3 glass melt permitted infiltration at ~ 700 °C inside an annealing oven apparatus by applying suction with the use of a standard mechanical vacuum pump, while its low glass transition temperature of ~ 190 °C allows structural relaxations at temperatures close to ambient and the formation of high quality glass strands inside the silica structure of the PCF. The AgPO3/silica PCF was characterized by means of its transmission spectrum that showed PBG guidance over the measurement range (350-1650nm). The effect of the AgPO3 glass photosensitivity on the guiding properties of the AgPO3/silica PCF was explored by employing a 355nm, 150 ps laser irradiation. The exposure gave rise to a photo-induced enhancement of the transmission-to-stop-band extinction ratio by ~60 dB/cm as well as bandwidth tuning. Numerical calculations of the transmission spectra of the AgPO3/silica PCF have been performed for confirming the experimental results and modelling the photo-induced variation of the two-glass fibre transmission. We believe that the fabrication of the AgPO3/silica PBG fibre constitutes a strong base for the development of new in-fibre sensing and scattering-based devices, by exploiting the high photosensitivity of silver and its specific plasmon absorption properties.

  2. Observation of frequency doubling in tantalum doped silica fibres

    NASA Technical Reports Server (NTRS)

    Driscoll, T. J.; Lawandy, N. M.; Killian, A.; Rienhart, L.; Morse, T. F.

    1991-01-01

    Second harmonic conversion efficients of 3 x 0,0001 in tantalum-doped silica fibers prepared by the seeding technique are reported. A series of experiments were conducted to characterize the frequency doubling in this fiber and to compare the results to the behavior observed in germanosilicate and rare earth-doped aluminosilicate fibers.

  3. Fabrication and characterization of cerium doped barium titanate/PMMA nanocomposites

    NASA Astrophysics Data System (ADS)

    Padalia, Diwakar; Bisht, Garima; Johri, U. C.; Asokan, K.

    2013-05-01

    The cerium doped barium titanate (BaTiO3:Ce)/poly methyl methacrylate(PMMA) polymer nano-composites (PNC) were successfully fabricated via solvent evaporation method with microwaves (2.4 GHz) heating. The X-ray diffraction measurements confirm the formation of barium titanate (BT) with crystallite size ranges from 55 to 62 nm. Differential scanning calorimetry study shows that the glass transition temperature (Tg) directly affected by microwaves heat treatment and particle size of filler. The broadband dielectric spectroscopy was employed to investigate the frequency and temperature dependence of the dielectric properties of the nanocomposites in a frequency range from 75 kHz to 5 MHz and temperature range 80-400 K. The introduction of different BT fillers in PMMA enhance the dielectric constant of PNCs drastically and give a smooth response in frequency range mentioned above. The loss factor of the composite can be suppressed by using cerium doped barium titanate filler rather than pure barium titanate filler.

  4. The effects of cerium doping on the size, morphology, and optical properties of α-hematite nanoparticles for ultraviolet filtration

    SciTech Connect

    Cardillo, Dean; Konstantinov, Konstantin; Devers, Thierry

    2013-11-15

    Highlights: • Possible application of cerium-doped α-hematite as ultraviolet filter. • Nanoparticles obtained through co-precipitation technique using various cerium doping levels followed by annealing. • Comprehensive materials characterisation utilizing XRD, DSC/TGA, STEM, UV–vis spectroscopy. • Increasing cerium content reduces particle sizing and alters morphology. • Solubility of cerium in hematite seen between 5 and 10% doping, 10% cerium doping greatly enhances attenuation in ultraviolet region and increases optical bandgap. - Abstract: Metal oxide nanoparticles have potential use in energy storage, electrode materials, as catalysts and in the emerging field of nanomedicine. Being able to accurately tailor the desirable properties of these nanoceramic materials, such as particle size, morphology and optical bandgap (E{sub g}) is integral in the feasibility of their use. In this study we investigate the altering of both the structure and physical properties through the doping of hematite (α-Fe{sub 2}O{sub 3}) nanocrystals with cerium at a range of concentrations, synthesised using a one-pot co-precipitation method. This extremely simple synthesis followed by thermal treatment results in stable Fe{sub 2−x}Ce{sub x}O{sub y} nanoceramics resulting from the burning of any unreacted precursors and transformation of goethite-cerium doped nanoparticle intermediate. The inclusion of Ce into the crystal lattice of these α-Fe{sub 2}O{sub 3} nanoparticles causes a significantly large reduction in mean crystalline size and alteration in particle morphology with increasing cerium content. Finally we report an increase optical semiconductor bandgap, along with a substantial increase in the ultraviolet attenuation found for a 10% Ce-doping concentration which shows the potential application of cerium-doped hematite nanocrystals to be used as a pigmented ultraviolet filter for cosmetic products.

  5. Sulfurization behavior of cerium doped uranium oxides by CS{sub 2}

    SciTech Connect

    Sato, Nobuaki; Kato, Shintaro; Kirishima, Akira; Tochiyama, Osamu

    2007-07-01

    For the recovery of nuclear materials from the spent nuclear fuel, the sulfide process has been proposed and the voloxidation of spent fuel and selective sulfurization rare-earth elements has been proposed. In this paper, cerium was used as a stand-in of plutonium and sulfurization behavior of cerium doped uranium dioxide by CS{sub 2} was studied. UO{sub 2} was oxidized to U{sub 3}O{sub 8} in air, while the Ce doped UO{sub 2} solid solution was formed in the presence of CeO{sub 2} by the heat treatment in air. The effect of heating time, temperature and the ratio of uranium to cerium on the formation of solid solution was analyzed. The results were also compared with those of thermodynamic consideration. (authors)

  6. The formation of light emitting cerium silicates in cerium-doped silicon oxides

    SciTech Connect

    Li Jing; Zalloum, Othman; Roschuk, Tyler; Heng Chenglin; Wojcik, Jacek; Mascher, Peter

    2009-01-05

    Cerium-doped silicon oxides with cerium concentrations of up to 0.9 at. % were deposited by electron cyclotron resonance plasma enhanced chemical vapor deposition. Bright cerium related photoluminescence, easily seen even under room lighting conditions, was observed from the films and found to be sensitive to film composition and annealing temperature. The film containing 0.9 at. % Ce subjected to anneal in N{sub 2} at 1200 deg. C for 3 h showed the most intense cerium-related emission, easily visible under bright room lighting conditions. This is attributed to the formation of cerium silicate [Ce{sub 2}Si{sub 2}O{sub 7} or Ce{sub 4.667} (SiO{sub 4}){sub 3}O], the presence of which was confirmed by high resolution transmission electron microscopy.

  7. Near-infrared luminescence of bismuth in fluorine-doped-core silica fibres.

    PubMed

    Bazakutsa, A P; Golant, K M

    2015-02-01

    Photoluminescence spectra and decay kinetics of bismuth inclusions in silica optical fibres containing fluorine additive in the core glass are studied in the vicinity of a wavelength of 1420 nm at temperatures of 80-900 K under a continuous wave (CW) and a pulsed diode laser pump at a wavelength of 808 nm. At high fluorine concentration and low temperatures, luminescence decay kinetics becomes essentially bi-exponential, typical lifetimes being 720 and 1200 µs. Hydrogen and deuterium loading at pressures of up to 125 bar leads to a decrease of the steady-state luminescence intensity and lifetime. We attribute this to the appearance of an energy transfer bridge from bismuth clusters to vibrational degrees of freedom of diatomic molecules. It is found that in the presence of H(2) or D(2) molecules experiencing random walking in silica, luminescence decay kinetics stop following a single exponential function even in fluorine-free silica-core fibre, deviation from the single exponent being greater at higher temperatures. The induced quenching rate increases with the increase of temperature as well and is greater for H(2) molecules. All conditions being equal, the equilibrium concentration of hydrogen molecules is greater in heavily fluorinated silica. At temperatures below ~250 K, the presence of dissolved molecules has no effect, which speaks for the primary importance of having rotational degrees of freedom of migrating interstitial diatomic molecules in an excited state for effective quenching of bismuth electronic excitations. It is found that the influence of dissolved deuterium is weaker than that of hydrogen. We attribute this feature to a greater angular momentum of the D(2) molecule and correspondingly smaller energy of the molecule's rotational quantum. The results of the experiments show that bismuth clusters mainly located in voids of the silica network, rather than bismuth point defects, are responsible for near-infrared luminescence. PMID:25836233

  8. Modified femtosecond laser inscription method for tailored grating sensors in encapsulated silica and low-loss polymer optical fibres

    NASA Astrophysics Data System (ADS)

    Kalli, Kyriacos; Lacraz, Amedee; Theodosiou, Andreas; Kofinas, Marios

    2016-05-01

    There is great interest in the development of flexible wavelength filters and optical fibre sensors, such as Bragg and superstructure gratings, grating arrays and chirped gratings in glass and polymer optical fibres. A major hurdle is the development of an inscription method that should offer flexibility and reliability and be generally applicable to all optical fibre types. With this in mind we have developed a novel femtosecond laser inscription method; plane-by-plane inscription, whereby a 3D-index change of controlled length across the fibre core, width along the fibre axis and depth is written into the optical fibre. We apply this method for the inscription of various grating types in coated silica and low- loss CYTOP polymer optical fibres. The plane-by-plane method allows for multiple and overlapping gratings in the fibre core. Moreover, we demonstrate that this novel fibre Bragg grating inscription technique can be used to modify and add versatility to an existing, encapsulated optical fibre pressure sensor. The femtosecond laser is operated in the green or the near infra-red, based on the material properties under laser modification.

  9. Exposure to Fibres, Crystalline Silica, Silicon Carbide and Sulphur Dioxide in the Norwegian Silicon Carbide Industry

    PubMed Central

    Føreland, S.; Bye, E.; Bakke, B.; Eduard, W.

    2008-01-01

    Objectives: The aim of this study was to assess personal exposure to fibres, crystalline silica, silicon carbide (SiC) and sulphur dioxide in the Norwegian SiC industry. Methods: Approximately 720 fibre samples, 720 respirable dust samples and 1400 total dust samples were collected from randomly chosen workers from the furnace, processing and maintenance departments in all three Norwegian SiC plants. The respirable dust samples were analysed for quartz, cristobalite and non-fibrous SiC content. Approximately 240 sulphur dioxide samples were collected from workers in the furnace department. Results: The sorting operators from all plants, control room and cleaning operators in Plant A and charger, charger/mix and payloader operators in Plant C had a geometric mean (GM) of fibre exposure above the Norwegian occupational exposure limit (OEL) (0.1 fibre cm−3). The cleaner operators in Plant A had the highest GM exposure to respirable quartz (20 μg m−3). The charger/mix operators in Plant C had the highest GM exposure to respirable cristobalite (38 μg m−3) and the refinery crusher operators in Plant A had the highest GM exposure to non-fibrous SiC (0.65 mg m−3). Exposure to the crystalline silica and non-fibrous SiC was generally low and between 0.4 and 2.1% of the measurements exceeded the OELs. The cleaner operators in Plant A had the highest GM exposure to respirable dust (1.3 mg m−3) and total dust (21 mg m−3). GM exposures for respirable dust above the Norwegian SiC industry-specific OEL of 0.5 mg m−3 were also found for refinery crusher operators in all plants and mix, charger, charger/mix and sorting operators in Plant C. Only 4% of the total dust measurements exceeded the OEL for nuisance dust of (10 mg m−3). Exposure to sulphur dioxide was generally low. However, peaks in the range of 10–100 p.p.m. were observed for control room and crane operators in Plants A and B and for charger and charger/mix operators in Plant C. Conclusion: Workers in

  10. Correlation between the energy level structure of cerium-doped yttrium aluminum garnet and luminescent behavior at varying temperatures

    NASA Astrophysics Data System (ADS)

    Song, Zhen; Liu, Xiaolang; He, Lizhu; Liu, Q. L.

    2016-05-01

    Luminescent spectra of cerium-doped yttrium aluminum garnet are measured at varying temperatures. It is found that the two excitation peaks demonstrate a reverse trend as the temperature rises, and the breadth of the high-energy emission peak experiences an abrupt widening. These effects could be directly linked to the energy level scheme of Ce3+ under the crystal field of local symmetry. Moreover, an alternative fitting function is provided which could effectively resolve the emission curve.

  11. Improved Czochralski growth and activator efficiency of cerium doped yttrium aluminum garnet by defect engineering

    NASA Astrophysics Data System (ADS)

    Haven, Drew Thomas

    The past several decades have seen a genuine surge in development of scintillator materials for use in a multitude of applications ranging from high energy physics to medical imaging. Despite the rapid materials discovery that has been undertaken in the search for better scintillators, a host of defects still limit scintillator performance in many promising materials. Thus the key to tapping into a scintillators full potential lies in understanding and modifying their defect structure through a process known as defect engineering. One such promising visible light scintillator is cerium doped yttrium aluminum garnet (Ce:YAG). Despite characteristics that make Ce:YAG an excellent yellow phosphor that see it commonly used in fluorescent lights and while light LEDs, performance hindering defects severely limited its potential as a bulk scintillator, a critical defect being that of UV defect luminescence. By successfully building a new Czochralski (CZ) furnace, samples could be grown with careful control over growth conditions to study and reduce these defects. All samples were grown in similar conditions by the CZ method with a (111) oriented undoped YAG seed. Several original approaches were developed in this study to reduce defects or mitigate their influence. The first method of solving the problem relied on recognizing that what many in the past identified as visible scintillation light was in fact UV defect luminescence. By using multiple photodetectors it was demonstrated that when higher cerium doping levels are involved in Ce:YAG, luminescence is not decreased due to self-absorption as previously thought, but rather UV defect emission is quenched in favor of visible emission. Once established, new avenues of research became available. Another study demonstrates Ce:YAG grown by the Czochralski method in alumina rich conditions is an effective method for reducing the number of UV producing yttrium antisite defects. This culminated in record energy resolution of

  12. Cerium doped soda-lime-silicate glasses: effects of silver ion-exchange on optical properties

    NASA Astrophysics Data System (ADS)

    Paje, S. E.; García, M. A.; Villegas, M. A.; Llopis, J.

    2001-09-01

    Effects of silver ion-exchange on optical absorption (OA) and photoluminescence (PL) spectra of a cerium doped soda-lime-silicate glass at room temperature are investigated. The optical spectra are described in terms of the characteristic transitions 4f↔5d originated in Ce 3+ ions placed mainly in two different sites of the glass network. As Ag + ions are introduced into the cerium doped glass, they are reduced to elementary silver (Ag 0) which are favoured by the reaction Ce 3++Ag +→Ce 4++Ag 0. Then, the number of Ce 3+ ions decrease inversely with depth from the surface contrarily to Ce 4+ ions does, and elementary silver diffuses and aggregates to form nanoparticles. As a consequence of these changes, the OA spectra of exchanged samples increase substantially in the UV range and the luminescence decreases significantly. The high sensitivity of PL together with deconvolution analysis of spectra, however, allows us to detect changes in the excitation and emission spectra from the earlier stages of ion-exchange. This indicates that during the ion-exchange we deal with fast processes (much shorter than 1 min). In fact, transmission electron microscopy observations of samples from the glass exchanged for a short time as 1 min at 325°C show the presence of a scanty number of silver nanoparticles, which confirms this point. Furthermore, with increasing the length of time of ion-exchange, PL spectra exhibit a progressive red shift indicative in part of a covalence increment in the oxygen-cerium coordinated bonding. We observe no luminescence from Ag + ions and other silver molecular species in contrast with other preliminary PL studies on silver ion-exchange in soda-lime-silicate glasses free of cerium. The effect is discussed on the basis of a supplementary increase in the number of Ce 4+ ions mainly due to the reaction Ce 3++Ag +→Ce 4++Ag 0, which prevents efficiently the luminescence of the silver centers.

  13. Radiant transmittance of cerium doped quartz from 300 to 1270K

    SciTech Connect

    Havstad, M.A.; Dingus, C.

    1997-03-14

    The transmittance of curved slabs of cerium doped quartz is reported as a function of wavelength and temperature. The spectral range of measurement is 0.25 to 0.725 {micro}m and temperature varies from 300K to 1270K. The short wavelength cutoff for transmission shifts to longer wavelengths monotonically with temperature at a rate of {approximately}3nm/l 00K. The tmnstnittance data for wavelengths less than 0.36 {micro}m are fit to a classical pole fit model using 8 modes (Oscillators) and the temperature dependence of the modes is given. For wavelengths beyond 0.36 {micro}m the data are fit to an ``Urbach rule.`` The bandgap parameter in the Urbach rule decreases linearly with temperature to 1270K and varies from 3.394eV at 300K to 3,183 eV at 1270K, while the steepness parameter also decreases approximately linearly from 8.51 eV{sup -1} to 5.80 eV{sup -1}. The fits are used to compute the spectral and temperature dependent absorption coefficient.

  14. Cerium Doped LSO/LYSO Crystal Development for future High Energy Physics Experiments

    SciTech Connect

    Ren-Yuan Zhu

    2012-03-25

    Because of their high stopping power and fast and bright scintillation, cerium doped LSO and LYSO crystals have attracted a broad interest in the physics community pursuing precision electromagnetic calorimeter for future high energy physics experiments. Their excellent radiation hardness against gamma-rays, neutrons and charged hadrons also makes them a preferred material for calorimeters to be operated in a severe radiation environment, such as the HL-LHC. An effort was made at SIPAT to grow 25 X{sub 0} (28 cm) long LYSO crystals for high energy physics applications. In this paper, the optical and scintillation properties and its radiation hardness against gamma-ray irradiations up to 1 Mrad are presented for the first 2.5 X 2.5 X 28 cm LYSO sample. An absorption band was found at the seed end of this sample and three other 20 cm long samples, which was traced back to a bad seed crystal used in the corresponding crystal growth process. Significant progresses in optical and scintillation properties were achieved for large size LYSO crystals after eliminating this absorption band.

  15. Nonlinear frequency up-conversion of femtosecond pulses from an erbium fibre laser to the range of 0.8 - 1 {mu}m in silica fibres

    SciTech Connect

    Anashkina, E A; Andrianov, A V; Kim, A V

    2013-03-31

    We consider different mechanisms of nonlinear frequency up-conversion of femtosecond pulses emitted by an erbium fibre system ({lambda} = 1.5 {mu}m) to the range of 0.8 - 1.2 {mu}m in nonlinear silica fibres. The generation efficiency and the centre frequencies of dispersive waves are found as functions of the parameters of the fibre and the input pulse. Simple analytical estimates are obtained for the spectral distribution of the intensity and the frequency shift of a wave packet in the region of normal dispersion during the emission of a high-order soliton under phase matching conditions. In the geometrical optics approximation the frequency shifts are estimated in the interaction of dispersive waves with solitons in various regimes. (extreme light fields and their applications)

  16. All-silica, large mode area, single mode photonic bandgap fibre with Fabry-Perot resonant structures

    NASA Astrophysics Data System (ADS)

    Várallyay, Zoltán; Kovács, Péter

    2016-03-01

    All-silica, photonic crystal fibres consisting of a low index, silica core surrounded by higher index inclusions embedded in a silica matrix to form a photonic bandgap cladding were numerically analysed. The aim of the investigations was to modify the guiding properties of the fibre by introducing resonant structural entities. These structural modifications are realised by altering the refractive index of certain high index inclusions in the photonic crystal cladding resulting in mode coupling between the core mode and the mode propagated in the modified index region. This results in an increased effective core area of the fundamental core mode and consequently decreased nonlinearity as well as modified effective index compared to the effective index of the unmodified structure and resonant dispersion profile that can be used for pulse compression or optical delay purposes.

  17. Thermoluminescence Response of Ge-Doped Cylindrical-, Flat- and Photonic Crystal Silica-Fibres to Electron and Photon Radiation.

    PubMed

    Entezam, A; Khandaker, M U; Amin, Y M; Ung, N M; Bradley, D A; Maah, J; Safari, M J; Moradi, F

    2016-01-01

    Study has been made of the thermoluminescence (TL) response of silica-based Ge-doped cylindrical, flat and photonic crystal fibres (referred to herein as PCF-collapsed) to electron (6, 12 and 20 MeV) and photon (6, 10 MV) irradiation and 1.25 MeV γ-rays, for doses from 0.1 Gy to 100 Gy. The electron and photon irradiations were delivered through use of a Varian Model 2100C linear accelerator located at the University of Malaya Medical Centre and γ-rays delivered from a 60Co irradiator located at the Secondary Standard Dosimetry Laboratory (SSDL), Malaysian Nuclear Agency. Tailor-made to be of various dimensions and dopant concentrations (6-10% Ge), the fibres were observed to provide TL yield linear with radiation dose, reproducibility being within 1-5%, with insensitivity to energy and angular variation. The sensitivity dependency of both detectors with respect to field size follows the dependency of the output factors. For flat fibres exposed to 6 MV X-rays, the 6% Ge-doped fibre provided the greatest TL yield while PCF-collapsed showed a response 2.4 times greater than that of the 6% Ge-doped flat fibres. The response of cylindrical fibres increased with core size. The fibres offer uniform response, high spatial resolution and sensitivity, providing the basis of promising TL systems for radiotherapy applications. PMID:27149115

  18. Thermoluminescence Response of Ge-Doped Cylindrical-, Flat- and Photonic Crystal Silica-Fibres to Electron and Photon Radiation

    PubMed Central

    Entezam, A.; Khandaker, M. U.; Amin, Y. M.; Ung, N. M.; Bradley, D. A.; Maah, J.; Safari, M. J.; Moradi, F.

    2016-01-01

    Study has been made of the thermoluminescence (TL) response of silica-based Ge-doped cylindrical, flat and photonic crystal fibres (referred to herein as PCF-collapsed) to electron (6, 12 and 20 MeV) and photon (6, 10 MV) irradiation and 1.25 MeV γ-rays, for doses from 0.1 Gy to 100 Gy. The electron and photon irradiations were delivered through use of a Varian Model 2100C linear accelerator located at the University of Malaya Medical Centre and γ-rays delivered from a 60Co irradiator located at the Secondary Standard Dosimetry Laboratory (SSDL), Malaysian Nuclear Agency. Tailor-made to be of various dimensions and dopant concentrations (6–10% Ge), the fibres were observed to provide TL yield linear with radiation dose, reproducibility being within 1–5%, with insensitivity to energy and angular variation. The sensitivity dependency of both detectors with respect to field size follows the dependency of the output factors. For flat fibres exposed to 6 MV X-rays, the 6% Ge-doped fibre provided the greatest TL yield while PCF-collapsed showed a response 2.4 times greater than that of the 6% Ge-doped flat fibres. The response of cylindrical fibres increased with core size. The fibres offer uniform response, high spatial resolution and sensitivity, providing the basis of promising TL systems for radiotherapy applications. PMID:27149115

  19. Synthesis and surface characterization of alumina-silica-zirconia nanocomposite ceramic fibres on aluminium at room temperature

    NASA Astrophysics Data System (ADS)

    Mubarak Ali, M.; Raj, V.

    2010-04-01

    Alumina-silica-zirconia nanocomposite (ASZNC) ceramic fibres were synthesized by conventional anodization route. Scanning Electron Microscopy (SEM), Atomic Force microscopy (AFM), X-Ray Diffraction (XRD) and Energy Dispersive X-Ray spectroscopy (EDAX) were used to characterize the morphology and crystalloid structure of ASZNC fibres. Current density (DC) is one of the important parameters to get the alumina-silica-zirconia nanocomposite (ASZNC) ceramic fibres by this route. Annealing of the films exhibited a drastic change in the properties due to improved crystallinity. The root mean square roughness of the sample observed from atomic force microscopic analysis is about 71.5 nm which is comparable to the average grain size of the coatings which is about 72 nm obtained from X-Ray diffraction. The results indicate that, the ASZNC fibres are arranged well in the nanostructure. The thickness of the coating increased with the anodizing time, but the coatings turned rougher and more porous. At the initial stage the growth of ceramic coating increases inwards to the metal substrate and outwards to the coating surface simultaneously. Subsequently, it mainly grows towards the metal substrate and the density of the ceramic coating increases gradually, which results in the decrease of the total thickness as anodizing time increases. This new approach of preparing ASZNC ceramic fibres may be important in applications ranging from gas sensors to various engineering materials.

  20. Band-gap modulation via gallium substitution in cerium doped gadolinium aluminum garnet using a mixed fuel combustion approach

    SciTech Connect

    Tyagi, Mohit; Pitale, Shreyas S.; Ghosh, Manoranjan; Shinde, Seema

    2014-04-24

    Cerium doped Gadolinium garnets (Gd{sub 3}Al{sub x}Ga{sub 5−x}O{sub 12} where 0≤x≤5) are synthesized via combustion synthesis using mixture of urea and glycine fuels. A 4h Post annealing at 1400 oC is found to be necessary for pure phase formation. Lattice spacing variation as a result of partial or total Ga substitution at Al site was mapped by X-ray diffraction. Photoluminescence emission of Ce shifts as a consequence of Ga substitution and therefore suggests a local re-adjustment of crystal field around activator site.

  1. Delivery of high energy Er:YAG pulsed laser light at 2.94 µm through a silica hollow core photonic crystal fibre.

    PubMed

    Urich, A; Maier, R R J; Mangan, B J; Renshaw, S; Knight, J C; Hand, D P; Shephard, J D

    2012-03-12

    In this paper the delivery of high power Er:YAG laser pulses through a silica hollow core photonic crystal fibre is demonstrated. The Er:YAG wavelength of 2.94 µm is well beyond the normal transmittance of bulk silica but the unique hollow core guidance allows silica to guide in this regime. We have demonstrated for the first time the ability to deliver high energy pulses through an all-silica fibre at 2.94 µm. These silica fibres are mechanically and chemically robust, biocompatible and have low sensitivity to bending. A maximum pulse energy of 14 mJ at 2.94 µm was delivered through the fibre. This, to our knowledge, is the first time a silica hollow core photonic crystal fibre has been shown to transmit 2.94 μm laser light at a fluence exceeding the thresholds required for modification (e.g. cutting and drilling) of hard biological tissue. Consequently, laser delivery systems based on these fibres have the potential for the realization of novel, minimally-invasive surgical procedures. PMID:22418551

  2. Highly sensitive optical fibre long period grating biosensor anchored with silica core gold shell nanoparticles.

    PubMed

    Marques, L; Hernandez, F U; James, S W; Morgan, S P; Clark, M; Tatam, R P; Korposh, S

    2016-01-15

    An optical fibre long period grating (LPG), modified with a coating of silica core gold shell (SiO2:Au) nanoparticles (NPs) deposited using the layer-by-layer method, was employed for the development of a biosensor. The SiO2:Au NPs were electrostatically assembled onto the LPG with the aid of a poly(allylamine hydrochloride) (PAH) polycation layer. The LPG sensor operates at the phase matching turning point to provide the highest sensitivity. The SiO2:Au NPs were modified with biotin, which was used as a ligand for streptavidin (SV) detection. The sensing mechanism is based on the measurement of the refractive index change induced by the binding of the SV to the biotin. The effect on sensitivity of increasing the surface area by virtue of the SiO2:Au nanoparticles' diameter and film thickness was studied. The lowest measured concentration of SV was 2.5nM, achieved using an LPG modified with a 3 layer (PAH/SiO2:Au) thin film composed of SiO2 NPs of 300nm diameter with a binding constant of k=1.7(pM)(-1), sensitivity of 6.9nm/ng/mm(2) and limit of detection of 19pg/mm(2). PMID:26319165

  3. Octave-spanning supercontinuum generation in highly nonlinear silica fibres based on cost-effective fibre amplifiers

    NASA Astrophysics Data System (ADS)

    Saldaña-Díaz, J. E.; Jarabo, S.; Salgado-Remacha, F. J.

    2016-09-01

    We report a simple method for supercontinuum generation. The set-up consists of an Er-doped mode-locked fibre laser, used as seed, and a highly nonlinear fibre with zero dispersion at 1550 nm. Thus, all the components are easily attainable. With this novel system the requirements in terms of control of dispersion are reduced. In addition, the spectral width is optimized using fibres with positive and negative dispersion. The supercontinuum emission is characterized by means of an optical spectrum analyser and a PbS photodetector, showing an octave-spanning spectral width, with a flat profile from 1100 nm up to 2100 nm. Compared to other supercontinuum sources, this new proposal results in a very competitive and attainable system, particularly in the 1500–2100 nm region.

  4. Characterisation of the thermoluminescence (TL) properties of tailor-made Ge-doped silica glass fibre for applications in medical radiation therapy dosimetry

    NASA Astrophysics Data System (ADS)

    Zahaimi, N. A.; Zin, H.; Mahdiraji, G. A.; Rahman, A. L. Abdul; Bradley, D. A.; Rahman, A. T. Abdul

    2014-11-01

    We have investigated the characterisation of new fabricated material Ge doped silica glass thermoluminescence TL dosimeter (Photonic Research Centre, University of Malaya) for medical radiation dosimetry at therapy energy. Previously, the dosimeter has been studied to provide ideal dosimetry system, suitable to ensure an accurate delivery of radiation doses to tumour tissue while minimising the amount of radiation administrated to healthy tissue. Both energies of photon and electron were used in this experiment for a dose range of 1 to 5 Gy. The various sizes of core diameter Ge doped silica glass (120, 241, 362, 483 and 604 μm) were exposed by using linear accelerator at Pantai Medical Centre. For both energies, the optical fibres were found to produce a flat response to a fixed photon and electron doses to within 4% (S.D) of the mean of the TL distribution. In terms of dose response, the fibres provide linear response over the range investigated, from a fraction of 1-5 Gy. The finding shows 120 μm fibres have 1.82 greater dose response than 604 pm fibres irradiated at 6 MV photon with a fixed dose of 3 Gy. While for electron energy 12 MeV, the response shows 120 μm fibres have 1.58 greater dose response compared to 604 μm fibres. The good responses are suitable to make these tailor-made doped silica fibres a promising TL material for use as a dosimetric system in medical radiation therapy.

  5. Rapid analysis of Achillea tenuifolia Lam essential oils by polythiophene/hexagonally ordered silica nanocomposite coating as a solid-phase microextraction fibre.

    PubMed

    Piryaei, Marzieh; Abolghasemi, Mir Mahdi; Nazemiyeh, Hossein

    2015-01-01

    In this work, a highly porous fibre coated with polythiophene/hexagonally ordered silica nanocomposite (PT/SBA-15) was prepared and used for extraction of essential oils with microwave-assisted distillation headspace solid phase microextraction (MA-HS-SPME) method. The prepared nanomaterials were immobilised on a stainless steel wire for fabrication of the SPME fibre. Using MA-HS-SPME followed by GC-MS, 24 compounds were separated and identified in Achillea tenuifolia, which mainly included limonene (28.6%), α-cadinol (12.7%), borneol (6.7%), caryophyllene oxide (3.2%), bornyl acetate (4.3%), camphene (3.2%) and para-cymene (2.3%). The experimental results showed that the polythiophene/hexagonally ordered silica nanocomposite fibres were suitable for the semi-quantitative study of the composition of essential oils in plant materials and for monitoring the variations in the volatile components of the plants. PMID:25613724

  6. Dosimetric characteristics of fabricated silica fibre for postal radiotherapy dose audits

    NASA Astrophysics Data System (ADS)

    Fadzil, M. S. Ahmad; Ramli, N. N. H.; Jusoh, M. A.; Kadni, T.; Bradley, D. A.; Ung, N. M.; Suhairul, H.; Mohd Noor, N.

    2014-11-01

    Present investigation aims to establish the dosimetric characteristics of a novel fabricated flat fibre TLD system for postal radiotherapy dose audits. Various thermoluminescence (TL) properties have been investigated for five sizes of 6 mol% Ge-doped optical fibres. Key dosimetric characteristics including reproducibility, linearity, fading and energy dependence have been established. Irradiations were carried out using a linear accelerator (linac) and a Cobalt-60 machine. For doses from 0.5 Gy up to 10 Gy, Ge-doped flat fibres exhibit linearity between TL yield and dose, reproducible to better than 8% standard deviation (SD) following repeat measurements (n = 3). For photons generated at potentials from 1.25 MeV to 10 MV an energy-dependent response is noted, with a coefficient of variation (CV) of less than 40% over the range of energies investigated. For 6.0 mm length flat fibres 100 μm thick × 350 pm wide, the TL fading loss following 30 days of storage at room temperature was < 8%. The Ge-doped flat fibre system represents a viable basis for use in postal radiotherapy dose audits, corrections being made for the various factors influencing the TL yield.

  7. The generation of optical phase conjugation from cerium doped barium titanate at wavelength of 632.8 nm

    NASA Astrophysics Data System (ADS)

    Sidakum, K.; Buranasiri, P.; Plaipichit, S.; Ruttanapun, C.; Jindajitawat, P.

    2013-06-01

    In this paper, optical phase conjugate beam with the using of different resonator configurations has been investigate. Two types of SPPC resonators were selected to use, the first one is linear resonators formed by crystal surface and the other one is linear resonators formed by single mirror and a photorefractive crystal. In our experiment, cerium doped barium titanate crystal (BaTiO3 : Ce) and He-Ne laser with wavelength of 632.8 nm have been used. From the results of both cases, the angle of the incident beams is optimum at 37.95° respect to the normal line of the surface that parallel to the c-axis of the crystal. The generating time of OPC beam are 150 seconds and 330 seconds for the first and second type resonators, respectively. The reflection ratios are equal to 8.75% and 5% for the first and second type resonators, respectively (the first type resonators could provide better reflection ratio).

  8. IR luminescence of tellurium-doped silica-based optical fibre

    SciTech Connect

    Dianov, Evgenii M; Alyshev, S V; Shubin, Aleksei V; Khopin, V F; Gur'yanov, Aleksei N

    2012-03-31

    Tellurium-doped germanosilicate fibre has been fabricated by the MCVD process. In contrast to Te-containing glasses studied earlier, it has a broad luminescence band (full width at half maximum of {approx}350 nm) centred at 1500 nm, with a lifetime of {approx}2 {mu}s. The luminescence of the fibre has been studied before and after gamma irradiation in a {sup 60}Co source to 309 and 992 kGy. The irradiation produced a luminescence band around 1100 nm, with a full width at half maximum of {approx}400 nm and lifetime of {approx}5 {mu}s. (letters)

  9. Sensitive protein detection using an optical fibre long period grating sensor anchored with silica core gold shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Marques, L.; Hernandez, F. U.; Korposh, S.; Clark, M.; Morgan, S.; James, S.; Tatam, R. P.

    2014-05-01

    An optical fibre long period grating (LPG), modified with a coating of silica gold (SiO2:Au) core/shell nanoparticles (NPs) deposited using the layer-by-layer (LbL) method, was employed for the development of a bio-sensor. The SiO2:Au NPs were electrostatically assembled onto the LPG with the aid of a poly(hydrochloride ammonium) (PAH) polycation layer. The LPG sensor operates at the phase matching turning point to provide the highest sensitivity. The SiO2:Au NPs were modified with biotin, which was used as a ligand for streptavidin (SV) detection. The sensing mechanism is based on the measurement of the refractive index change induced by the binding of the SV to the biotin. The lowest detected concentration of SV was 19 nM using an LPG modified with a 3 layer (PAH/SiO2:Au) thin film.

  10. Flexible delivery of Er:YAG radiation at 2.94 μm with novel hollow-core silica glass fibres: demonstration of tissue ablation

    NASA Astrophysics Data System (ADS)

    Urich, Artur; Maier, Robert R. J.; Knight, Jonathan C.; Yu, Fei; Hand, Duncan P.; Shephard, Jonathan D.

    2013-03-01

    In this work we present the delivery of high energy Er:YAG laser pulses operating at 2.94 μm through a hollow-core negative curvature fibre (HC-NCF) and a hollow-core photonic crystal fibre (HC-PCF) and their use for the ablation of biological tissue. In HC-NCF fibres, which have been developed recently, the laser radiation is confined in a hollow core and by an anti-resonant or reflection principle (also known as ARROW). Both fibres are made of fused silica which has high mechanical and chemical durability, is bio-inert and results in a fibre with the flexibility that lends itself to easy handling and minimally invasive procedures. The HC-NCF structure consists of only one ring of capillaries around a realtively large core, followed by a protecting outer layer, hence the preform is relatively easy to build compared to traditional HC-PCF. The measured attenuation at 2.94 μm is 0.06 dB/m for the HC-NCF and 1.2 dB/m for the HC-PCF. Both fibres have a single mode output beam profile which can be advantageous for surgical applications as the beam profile is maintained during fibre movement. We demonstrate delivery of high energy pulses through both fibres, well above the thresholds needed for the ablation of biological tissue in non-contact and contact mode. Delivered energy densities reached > 750 J/cm-2 after 10 m of HC-NCF and > 3400 J/cm2 through a 44 cm HC-PCF.

  11. Scintillation and Luminescence Properties of Undoped and Cerium-doped LiGdCl4 and NaGdCl4

    SciTech Connect

    Porter-Chapman, Yetta D.; Bourret-Courchesne, Edith D.; Bizarri, Gregory; Weber, Marvin J.; Derenzo, Stephen E.

    2008-10-05

    We report the scintillation properties of the undoped and cerium-doped variations of LiGdCl4 and NaGdCl4. Powder samples of these materials exhibit significant scintillation under X-rays. The samples were synthesized by solid-state methods from a 1:1 molar ratio of lithium or sodium chloride and gadolinium chloride. Cerium trichloride was used as the dopant. The physical, optical, and scintillation properties of these materials were analyzed by powder X-ray diffraction, photoluminescence, X-ray excited luminescence, and pulsed X-ray luminosity measurements. Increases in light yields are observed as the concentration of cerium increases. The highest light yields occurred at 20 percent cerium doping for both compounds. At larger concentrations neither compound formed, indicating a breakdown of the lattice with the addition of large amounts of cerium cations. At 20 percent cerium, LiGdCl4 and NaGdCl4 display scintillation light 3.6 times and 2.2 times the light yield of the reference material, YAlO3:Ce3+, respectively. Both emit in the ranges of 340 ? 350 nm and 365 - 370 nm and display multiexponential decays with cerium-like decay components at 33 ns (LiGdCl4:Ce) and 26 ns (NaGdCl4:Ce).

  12. Room-temperature scintillation properties of cerium-doped REOX (RE=Y, La, Gd, and Lu; X=F, Cl, Br, and I)

    SciTech Connect

    Eagleman, Yetta; Bourret-Courchesne, Edith; Derenzo, Stephen

    2010-12-10

    The scintillation properties of cerium-doped oxyhalides following the general formula REOX (RE=Y, La, Gd, and Lu; X=F, Cl, Br, and I) are reported. These materials were synthesized under dry conditions as microcrystalline powders from conventional solid state reactions. The room temperature X-ray excited emission and scintillation decay curves were measured and analyzed for each material. Additionally, the hygroscopic nature of the oxychlorides and oxybromides was compared to that of their corresponding rare earth halides. The yttrium, lanthanum, and gadolinium oxychlorides, and all of the oxybromides and oxyiodides are found to be activated by Ce{sup 3+}. GdOBr doped with 0.5% Ce{sup 3+} has the highest light output with a relative luminosity of about one-half that of LaBr{sub 3}: Ce{sup 3+}. It displays a single exponential decay of 30 ns.

  13. Probing shallow electron traps in cerium-doped Gd3Al2Ga3O12 scintillators by UV-induced absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Kitaura, Mamoru; Kamada, Kei; Kurosawa, Shunsuke; Azuma, Junpei; Ohnishi, Akimasa; Yamaji, Akihiro; Hara, Kazuhiko

    2016-07-01

    From measuring absorption spectra of cerium-doped Gd3Al2Ga3O12 (Ce:GAGG) and undoped GAGG crystals at low temperatures under UV-light irradiation, we find that they exhibit a broad band at around 12000 cm‑1. This band is enhanced by high-temperature annealing under a hydrogen atmosphere. On the basis of present experimental results, the UV-induced band is assigned to shallow electron traps of defect complexes associated with oxygen vacancies. The UV-induced band completely disappears with Mg2+ codoping. We conclude that the Mg2+ codoping has the effect of inhibiting the formation of shallow electron traps, which realizes a faster scintillation response of Ce:GAGG.

  14. Crystal growth and optical characterization of cerium-doped Lu1.8Y0.2SiO5

    NASA Astrophysics Data System (ADS)

    Cooke, D. W.; McClellan, K. J.; Bennett, B. L.; Roper, J. M.; Whittaker, M. T.; Muenchausen, R. E.; Sze, R. C.

    2000-12-01

    Czochralski growth of cerium-doped Lu1.8Y0.2SiO5 (LYSO) from a 90/10 solution of Lu2SiO5 (LSO) and Y2SiO5 (YSO) is demonstrated. The alloyed scintillator retains the favorable growth properties of YSO and the desirable physical and optical scintillator properties of LSO. Radioluminescence, thermally stimulated luminescence, optical absorption, and lifetime measurements confirm the equivalence of LYSO and LSO optical properties. Advantages of LYSO Czochralski growth relative to LSO include reduced melting point, less propensity for formation of crystalline inclusions, lower cost of starting material, and easier incorporation of cerium into the host lattice. This material offers an attractive alternative to LSO for scintillator applications.

  15. Fibre gratings and their applications

    SciTech Connect

    Vasil'ev, Sergei A; Medvedkov, O I; Korolev, I G; Bozhkov, A S; Kurkov, Andrei S; Dianov, Evgenii M

    2005-12-31

    A brief review is given of the state of the art in the research on the photosensitivity of fibres and photoinduced fibre gratings. The most important properties of fibre gratings are considered and the main methods of their production and their applications are discussed. The photosensitive compositions of silica glasses are presented and methods for increasing their photosensitivity are indicated. (review)

  16. Synthesis and photoluminescence properties of cerium-doped terbium-yttrium aluminum garnet phosphor for white light-emitting diodes applications

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Han, Tao; Lang, Tianchun; Tu, Mingjing; Peng, Lingling

    2015-11-01

    Cerium-doped terbium-yttrium aluminum garnet phosphors were synthesized using the solid-state reaction method. The crystalline phase, morphology, and photoluminescence properties were characterized by x-ray diffraction (XRD), scanning electron microscope (SEM), and fluorescence spectrophotometer, respectively. The XRD results indicate that with an increase of the amount of x (Tb3+), all of the samples have a pure garnet crystal structure without secondary phases. The SEM images reveal that the samples are composed of sphere-like crystallites, which exhibit different degrees of agglomeration. The luminescent properties of Ce ions in )Al5O12∶Ce0.1 have been studied, and it was found that the emission band shifted toward a longer wavelength. The redshift is attributed to the lowering of the 5d energy level centroid of Ce, which can be explained by the nephelauxetic effect and compression effect. These phosphors were coated on blue light-emitting diode (LED) chips to fabricate white light-emitting diodes (WLEDs), and their color-rendering indices, color temperatures, and luminous efficiencies were measured. As a consequence of the addition of Tb, the blue LED pumped )Al5O12∶Ce0.1 phosphors WLEDs showed good optical properties.

  17. OPTICAL FIBRES AND FIBREOPTIC SENSORS: Bismuth-ring-doped fibres

    NASA Astrophysics Data System (ADS)

    Zlenko, Aleksandr S.; Akhmetshin, Ural G.; Dvoirin, Vladislav V.; Bogatyrev, Vladimir A.; Firstov, Sergei V.

    2009-11-01

    A new process for bismuth doping of optical fibres is proposed in which the dopant is introduced into a thin layer surrounding the fibre core. This enables bismuth stabilisation in the silica glass, with no limitations on the core composition. In particular, the GeO2 content of the fibre core in this study is 16 mol %. Spectroscopic characterisation of such fibres and optical gain measurements suggest that the proposed approach has considerable potential for laser applications.

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

  19. Bismuth-ring-doped fibres

    SciTech Connect

    Zlenko, Aleksandr S; Dvoirin, Vladislav V; Bogatyrev, Vladimir A; Firstov, Sergei V; Akhmetshin, Ural G

    2009-11-30

    A new process for bismuth doping of optical fibres is proposed in which the dopant is introduced into a thin layer surrounding the fibre core. This enables bismuth stabilisation in the silica glass, with no limitations on the core composition. In particular, the GeO{sub 2} content of the fibre core in this study is 16 mol %. Spectroscopic characterisation of such fibres and optical gain measurements suggest that the proposed approach has considerable potential for laser applications. (optical fibres and fibreoptic sensors)

  20. A physical model of the photo- and radiation-induced degradation of ytterbium-doped silica optical fibres

    SciTech Connect

    Mady, Franck Duchez, Jean-Bernard Mebrouk, Yasmine Benabdesselam, Mourad

    2014-10-21

    We propose a model to describe the photo- or/and the radiation-induced darkening of ytterbium-doped silica optical fibers. This model accounts for the well-established experimental features of photo-darkening. Degradation behaviors predicted for fibers pumped in harsh environments are also fully confirmed by experimental data reported in the work by Duchez et al. (this proceeding), which gives a detailed characterization of the interplay between the effects of the pump and those of a superimposed ionizing irradiation (actual operation conditions in space-based applications for instance). In particular, dependences of the darkening build-up on the pump power, the total ionizing dose and the dose rate are all correctly reproduced. The presented model is a ‘sufficient’ one, including the minimal physical ingredients required to reproduce experimental features. Refinements could be proposed to improve, e.g., quantitative kinetics.

  1. Zero-dark-counting high-speed X-ray photon detection using a cerium-doped yttrium aluminum perovskite crystal and a small photomultiplier tube and its application to gadolinium imaging

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Satoshi; Sato, Eiichi; Oda, Yasuyuki; Nakamura, Ryuji; Oikawa, Hirobumi; Yabuushi, Tomonori; Ariga, Hisanori; Ehara, Shigeru

    2014-04-01

    X-ray photons are detected using a cerium-doped yttrium aluminum perovskite [YAP(Ce)] single-crystal scintillator with a decay time of 30 ns and a small-sized photomultiplier tube (SPMT). The negative output pulse from the SPMT is amplified by a high-speed inverse amplifier, and the event pulses are sent to a multichannel analyzer to measure X-ray spectra. The energy resolution of the spectrometer was 15% at 59.5 keV. We carried out photon-counting computed tomography using gadolinium media with a maximum rate of 650 kilo counts per second and confirmed the energy-dispersive effect with changes in the description voltage of event pulses using a high-speed comparator.

  2. Pairing type change upon an increase in the cerium doping level in the Nd{sub 2-x}Ce{sub x}CuO{sub 4+{delta}} electronic superconductor

    SciTech Connect

    Charikova, T. B. Kharus, G. I.; Shelushinina, N. G.; Petukhova, O. E.; Ivanov, A. A.

    2012-03-15

    We report on the results of analyzing the temperature dependences of the resistivity of the Nd{sub 2-x}Ce{sub x}CuO{sub 4+{delta}} electronic superconductor with x = 0.14 (underdoped range), x = 0.15 (optimal doping), and x = 0.18 (overdoped range) and with various degrees of annealing in an oxygen-free atmosphere in magnetic fields up to H = 90 kOe (H Double-Vertical-Line c, J Double-Vertical-Line ab) in the temperature range T = (0.4-300) K. It is shown that the observed differences in the dependences of the slope of the upper critical field dH{sub c2}/dT)|{sub Tc} on the degree of disorder in the Nd{sub 2-x}Ce{sub x}CuO{sub 4+{delta}} system upon a change in the cerium doping level indicate a change in the symmetry of d-type pairing to anisotropic s pairing.

  3. Hierarchical Order of Influence of Mix Variables Affecting Compressive Strength of Sustainable Concrete Containing Fly Ash, Copper Slag, Silica Fume, and Fibres

    PubMed Central

    Natarajan, Sakthieswaran; Karuppiah, Ganesan

    2014-01-01

    Experiments have been conducted to study the effect of addition of fly ash, copper slag, and steel and polypropylene fibres on compressive strength of concrete and to determine the hierarchical order of influence of the mix variables in affecting the strength using cluster analysis experimentally. While fly ash and copper slag are used for partial replacement of cement and fine aggregate, respectively, defined quantities of steel and polypropylene fibres were added to the mixes. It is found from the experimental study that, in general, irrespective of the presence or absence of fibres, (i) for a given copper slag-fine aggregate ratio, increase in fly ash-cement ratio the concrete strength decreases and with the increase in copper slag-sand ratio also the rate of strength decrease and (ii) for a given fly ash-cement ratio, increase in copper slag-fine aggregate ratio increases the strength of the concrete. From the cluster analysis, it is found that the quantities of coarse and fine aggregate present have high influence in affecting the strength. It is also observed that the quantities of fly ash and copper slag used as substitutes have equal “influence” in affecting the strength. Marginal effect of addition of fibres in the compression strength of concrete is also revealed by the cluster analysis. PMID:24707213

  4. Hierarchical order of influence of mix variables affecting compressive strength of sustainable concrete containing fly ash, copper slag, silica fume, and fibres.

    PubMed

    Natarajan, Sakthieswaran; Karuppiah, Ganesan

    2014-01-01

    Experiments have been conducted to study the effect of addition of fly ash, copper slag, and steel and polypropylene fibres on compressive strength of concrete and to determine the hierarchical order of influence of the mix variables in affecting the strength using cluster analysis experimentally. While fly ash and copper slag are used for partial replacement of cement and fine aggregate, respectively, defined quantities of steel and polypropylene fibres were added to the mixes. It is found from the experimental study that, in general, irrespective of the presence or absence of fibres, (i) for a given copper slag-fine aggregate ratio, increase in fly ash-cement ratio the concrete strength decreases and with the increase in copper slag-sand ratio also the rate of strength decrease and (ii) for a given fly ash-cement ratio, increase in copper slag-fine aggregate ratio increases the strength of the concrete. From the cluster analysis, it is found that the quantities of coarse and fine aggregate present have high influence in affecting the strength. It is also observed that the quantities of fly ash and copper slag used as substitutes have equal "influence" in affecting the strength. Marginal effect of addition of fibres in the compression strength of concrete is also revealed by the cluster analysis. PMID:24707213

  5. Cerium-activated sol–gel silica glasses for radiation dosimetry in harsh environment

    NASA Astrophysics Data System (ADS)

    El Hamzaoui, Hicham; Capoen, Bruno; Helou, Nissrine Al; Bouwmans, Géraud; Ouerdane, Youcef; Boukenter, Aziz; Girard, Sylvain; Marcandella, Claude; Duhamel, Olivier; Chadeyron, Geneviève; Mahiou, Rachid; Bouazaoui, Mohamed

    2016-04-01

    Cerium-doped silica glass has been prepared for ionizing radiation dosimetry applications, using the sol–gel route and densification under different atmospheres. In comparison with the glass densified under air atmosphere, the one obtained after sintering the xerogel under helium gas presents improved optical properties, with an enhancement of the photoluminescence quantum yield up to 33%, which is attributed to a higher Ce3+ ions concentration. Such a glassy rod has been jacketed in a quartz tube and then drawn at high temperature to a cane, which has been used as active material in a fibered remote x-ray radiation dosimeter. The sample exhibited a reversible linear radioluminescence intensity response versus the dose rate up to 30 Gy s‑1. These results confirm the potentialities of this material for in vivo or high rate dose remote dosimetry measurements.

  6. Peculiarities of the photosensitivity of low-loss phosphosilica fibres

    SciTech Connect

    Larionov, Yu V; Rybaltovsky, A A; Semenov, S L; Bubnov, M M; Dianov, Evgenii M

    2002-02-28

    The peculiarities of the refractive-index change in low-loss heavily P{sub 2}O{sub 5}-doped silica fibres fabricated by the MCVD method caused by irradiation with UV light are studied. The pre-exposure effect is found in these fibres. The mechanisms of the refractive-index change in phosphosilica and germanosilica fibres are considered and compared in the presence of this effect. (optical fibres)

  7. Photosensitivity of optical fibres doped with different impurities

    SciTech Connect

    Larionov, Yu V; Rybaltovsky, A A; Semenov, S L; Vartapetov, Sergei K; Kurzanov, M A; Obidin, Aleksei Z

    2004-02-28

    Photosensitivities of hydrogen-loaded silica fibres doped with germanium, phosphorus, antimony, and aluminium are estimated and compared. It is shown that although all the fibres can be pre-exposed, the degree of this effect is noticeably different for different fibres because the induction of the refractive index is determined by a combined contribution from a one-step photochemical reaction and a two-step reaction responsible for pre-exposure. One-step reactions dominate in more photosensitive optical fibres, while two-step reactions dominate in less photosensitive fibres. (optical fibres)

  8. Highly efficient Raman distributed feedback fibre lasers.

    PubMed

    Shi, Jindan; Alam, Shaif-ul; Ibsen, Morten

    2012-02-27

    We demonstrate highly efficient Raman distributed feedback (DFB) fibre lasers for the first time with up to 1.6 W of continuous wave (CW) output power. The DFB Bragg gratings are written directly into two types of commercially available passive germano-silica fibres. Two lasers of 30 cm length are pumped with up to 15 W of CW power at 1068 nm. The threshold power is ~2 W for a Raman-DFB (R-DFB) laser written in standard low-NA fibre, and only ~1 W for a laser written in a high-NA fibre, both of which oscillate in a narrow linewidth of <0.01 nm at ~1117 nm and ~1109 nm, respectively. The slope efficiencies are ~74% and ~93% with respect to absorbed pump power in the low-NA fibre and high-NA fibre respectively. Such high conversion efficiency suggests that very little energy is lost in the form of heat through inefficient energy transfer. Our results are supported by numerical simulations, and furthermore open up for the possibility of having narrow linewidth all-fibre laser sources in wavelength bands not traditionally covered by rare-earth doped silica fibres. Simulations also imply that this technology has the potential to produce even shorter R-DFB laser devices at the centimetre-level and with mW-level thresholds, if Bragg gratings formed in fibre materials with higher intrinsic Raman gain coefficient than silica are used. These materials include for example tellurite or chalcogenide glasses. Using glasses like these would also open up the possibility of having narrow linewidth fibre sources with DFB laser oscillating much further into the IR than what currently is possible with rare-earth doped silica glasses. PMID:22418313

  9. A compact polymer optical fibre ultrasound detector

    NASA Astrophysics Data System (ADS)

    Broadway, Christian; Gallego, Daniel; Pospori, Andreas; Zubel, Michal; Webb, David J.; Sugden, Kate; Carpintero, Guillermo; Lamela, Horacio

    2016-03-01

    Polymer optical fibre (POF) is a relatively new and novel technology that presents an innovative approach for ultrasonic endoscopic applications. Currently, piezo electric transducers are the typical detectors of choice, albeit possessing a limited bandwidth due to their resonant nature and a sensitivity that decreases proportionally to their size. Optical fibres provide immunity from electromagnetic interference and POF in particular boasts more suitable physical characteristics than silica optical fibre. The most important of these are lower acoustic impedance, a reduced Young's Modulus and a higher acoustic sensitivity than single-mode silica fibre at both 1 MHz and 10 MHz. POF therefore offers an interesting alternative to existing technology. Intrinsic fibre structures such as Bragg gratings and Fabry-Perot cavities may be inscribed into the fibre core using UV lasers. These gratings are a modulation of the refractive index of the fibre core and provide the advantages of high reflectivity, customisable bandwidth and point detection. We present a compact in fibre ultrasonic point detector based upon a POF Bragg grating (POFBG) sensor. We demonstrate that the detector is capable of leaving a laboratory environment by using connectorised fibre sensors and make a case for endoscopic ultrasonic detection through use of a mounting structure that better mimics the environment of an endoscopic probe. We measure the effects of water immersion upon POFBGs and analyse the ultrasonic response for 1, 5 and 10 MHz.

  10. Yb-, Er-Yb-, and Nd-doped fibre lasers based on multi-element first cladding fibres

    SciTech Connect

    Bufetov, Igor' A; Bubnov, M M; Mel'kumov, Mikhail A; Dudin, V V; Shubin, Aleksei V; Semenov, S L; Kravtsov, K S; Dianov, Evgenii M; Gur'yanov, A N; Yashkov, M V

    2005-04-30

    Single-mode cw Yb-, Er-Yb, and Nd-doped fibre lasers are fabricated by using fibres of a complicated structure (a few silica fibres in optical contact with each other are surrounded by a polymer jacket). Such a structure allows the coupling of radiation from several pump sources into one active fibre, providing an increase in the output power of the fibre laser. The Yb-doped fibre lasers with the output power above 50 W and efficiency {approx}65% and the 1.608-{mu}m Er-Yb-doped fibre laser pumped to the absorption band of Yb are fabricated and studied. The Nd-doped fibre lasers based on such fibres and emitting at 0.92 and 1.06 {mu}m are manufactured for the first time. (lasers)

  11. Fibre typing of intrafusal fibres.

    PubMed

    Thornell, Lars-Eric; Carlsson, Lena; Eriksson, Per-Olof; Liu, Jing-Xia; Österlund, Catharina; Stål, Per; Pedrosa-Domellöf, Fatima

    2015-08-01

    The first descriptions of muscle spindles with intrafusal fibres containing striated myofibrils and nervous elements were given approximately 150 years ago. It took, however, another 100 years to establish the presence of two types of intrafusal muscle fibres: nuclear bag and nuclear chain fibres. The present paper highlights primarily the contribution of Robert Banks in fibre typing of intrafusal fibres: the confirmation of the principle of two types of nuclear bag fibres in mammalian spindles and the variation in occurrence of a dense M-band along the fibres. Furthermore, this paper summarizes how studies from the Umeå University group (Laboratory of Muscle Biology in the Department of Integrative Medical Biology) on fibre typing and the structure and composition of M-bands have contributed to the current understanding of muscle spindle complexity in adult humans as well as to muscle spindle development and effects of ageing. The variable molecular composition of the intrafusal sarcomeres with respect to myosin heavy chains and M-band proteins gives new perspectives on the role of the intrafusal myofibrils as stretch-activated sensors influencing tension/stiffness and signalling to nuclei. PMID:26179023

  12. Fibre typing of intrafusal fibres

    PubMed Central

    Thornell, Lars-Eric; Carlsson, Lena; Eriksson, Per-Olof; Liu, Jing-Xia; Österlund, Catharina; Stål, Per; Pedrosa-Domellöf, Fatima

    2015-01-01

    The first descriptions of muscle spindles with intrafusal fibres containing striated myofibrils and nervous elements were given approximately 150 years ago. It took, however, another 100 years to establish the presence of two types of intrafusal muscle fibres: nuclear bag and nuclear chain fibres. The present paper highlights primarily the contribution of Robert Banks in fibre typing of intrafusal fibres: the confirmation of the principle of two types of nuclear bag fibres in mammalian spindles and the variation in occurrence of a dense M-band along the fibres. Furthermore, this paper summarizes how studies from the Umeå University group (Laboratory of Muscle Biology in the Department of Integrative Medical Biology) on fibre typing and the structure and composition of M-bands have contributed to the current understanding of muscle spindle complexity in adult humans as well as to muscle spindle development and effects of ageing. The variable molecular composition of the intrafusal sarcomeres with respect to myosin heavy chains and M-band proteins gives new perspectives on the role of the intrafusal myofibrils as stretch-activated sensors influencing tension/stiffness and signalling to nuclei. PMID:26179023

  13. Negative curvature fibres: exploiting the potential for novel optical sensors

    NASA Astrophysics Data System (ADS)

    Novo, C. C.; Urich, A.; Choudhury, D.; Carter, R.; Hand, D. P.; Thomson, R. R.; Yu, F.; Knight, J. C.; Brooks, S.; Mcculloch, S.; Shephard, J. D.

    2015-09-01

    One of the main challenges for fibre optic based sensing is robust operation in the mid-infrared (mid-IR) region. This is of major interest because this wavelength region is where the characteristic absorption spectra for a wide range of molecules lie. However, due to the high absorption of silica (above 2 μm), mid-IR sensors based on solid core silica fibres are not practical. Of the many alternatives to solid silica fibres, hollow core microstrutured optical fibres are being explored and show great promise. One relatively new fibre, the hollow core negative curvature fibre (NCF) is promising for novel optical devices due to the simple structure (in comparison to other microstructured fibres) in combination with a hollow core which enables low loss mid-IR infrared guidance in a silica based fibre. In this paper, an all silica NCF that is post-processed with a fs laser, in order to increase access to the hollow core, is presented with acceptable loss and significant potential for mid-IR gas sensing.

  14. Lax Pair, Conservation Laws, Solitons, and Rogue Waves for a Generalised Nonlinear Schrödinger-Maxwell-Bloch System under the Nonlinear Tunneling Effect for an Inhomogeneous Erbium-Doped Silica Fibre

    NASA Astrophysics Data System (ADS)

    Gao, Zhe; Gao, Yi-Tian; Su, Chuan-Qi; Wang, Qi-Min; Mao, Bing-Qing

    2016-01-01

    Under investigation in this article is a generalised nonlinear Schrödinger-Maxwell-Bloch system for the picosecond optical pulse propagation in an inhomogeneous erbium-doped silica optical fibre. Lax pair, conservation laws, Darboux transformation, and generalised Darboux transformation for the system are constructed; with the one- and two-soliton solutions, the first- and second-order rogue waves given. Soliton propagation is discussed. Nonlinear tunneling effect on the solitons and rogue waves are investigated. We find that (i) the detuning of the atomic transition frequency from the optical pulse frequency affects the velocity of the pulse when the detuning is small, (ii) nonlinear tunneling effect does not affect the energy redistribution of the soliton interaction, (iii) dispersion barrier/well has an effect on the soliton velocity, whereas nonlinear well/barrier does not, (iv) nonlinear well/barrier could amplify/compress the solitons or rogue waves in a smoother manner than the dispersion barrier/well, and (v) dispersion barrier could "attract" the nearby rogue waves, whereas the dispersion well has a repulsive effect on them.

  15. Random distributed feedback fibre lasers

    NASA Astrophysics Data System (ADS)

    Turitsyn, Sergei K.; Babin, Sergey A.; Churkin, Dmitry V.; Vatnik, Ilya D.; Nikulin, Maxim; Podivilov, Evgenii V.

    2014-09-01

    The concept of random lasers exploiting multiple scattering of photons in an amplifying disordered medium in order to generate coherent light without a traditional laser resonator has attracted a great deal of attention in recent years. This research area lies at the interface of the fundamental theory of disordered systems and laser science. The idea was originally proposed in the context of astrophysics in the 1960s by V.S. Letokhov, who studied scattering with “negative absorption” of the interstellar molecular clouds. Research on random lasers has since developed into a mature experimental and theoretical field. A simple design of such lasers would be promising for potential applications. However, in traditional random lasers the properties of the output radiation are typically characterized by complex features in the spatial, spectral and time domains, making them less attractive than standard laser systems in terms of practical applications. Recently, an interesting and novel type of one-dimensional random laser that operates in a conventional telecommunication fibre without any pre-designed resonator mirrors-random distributed feedback fibre laser-was demonstrated. The positive feedback required for laser generation in random fibre lasers is provided by the Rayleigh scattering from the inhomogeneities of the refractive index that are naturally present in silica glass. In the proposed laser concept, the randomly backscattered light is amplified through the Raman effect, providing distributed gain over distances up to 100 km. Although an effective reflection due to the Rayleigh scattering is extremely small (˜0.1%), the lasing threshold may be exceeded when a sufficiently large distributed Raman gain is provided. Such a random distributed feedback fibre laser has a number of interesting and attractive features. The fibre waveguide geometry provides transverse confinement, and effectively one-dimensional random distributed feedback leads to the generation

  16. Erbium-doped aluminophosphosilicate optical fibres

    SciTech Connect

    Likhachev, M E; Bubnov, M M; Zotov, K V; Medvedkov, O I; Lipatov, D S; Yashkov, M V; Gur'yanov, Aleksei N

    2010-09-10

    We have studied the active properties of erbium-doped aluminophosphosilicate (APS) core fibres in wide ranges of erbia, alumina and phosphorus pentoxide concentrations. The absorption and luminescence spectra of the P{sub 2}O{sub 5}- or Al{sub 2}O{sub 3}-enriched erbium-doped APS fibres are shown to be similar to those of the erbium-doped fibres singly doped with phosphorus pentoxide or alumina, respectively. The formation of AlPO{sub 4} in APS fibres leads not only to a reduction in the refractive index of the glass but also to a marked increase in Er{sub 2}O{sub 3} solubility in silica. (optical fibres)

  17. Raman fibre lasers emitting at a wavelength above 2 {mu}m

    SciTech Connect

    Dianov, Evgenii M; Bufetov, Igor' A; Mashinsky, V M; Neustruev, V B; Medvedkov, O I; Shubin, Aleksei V; Mel'kumov, Mikhail A; Gur'yanov, A N; Khopin, V F; Yashkov, M V

    2004-08-31

    Single-mode Raman fibre lasers emitting a few hundreds of millwatts at wavelengths of 2.0 and 2.2 {mu}m are built for the first time. Laser emission was amplified in a fibre with a germanium dioxide core and a silica cladding pumped by an Er/Yb-doped fibre laser. (lasers)

  18. Bi-doped fibre lasers and amplifiers emitting in a spectral region of 1.3 {mu}m

    SciTech Connect

    Dianov, E M; Firstov, S V; Bufetov, I A; Khopin, V F; Gur'yanov, A N

    2008-07-31

    A bismuth-doped fibre laser emitting at wavelengths within the second transparency window of silica fibres is fabricated. It is shown that Bi-doped aluminium-free phosphogermanosilicate fibres pumped in the regions of 800 and 1200 nm have the amplification band at 1275-1375 nm. (letters)

  19. Gamma-irradiation tests of IR optical fibres for ITER thermography--a case study

    SciTech Connect

    Reichle, R.; Pocheau, C.; Jouve, M.

    2008-03-12

    In the course of the development of a concept for a spectrally resolving infrared thermography diagnostic for the ITER divertor we have tested 3 types of infrared (IR) fibres in Co{sup 60} irradiation facilities under {gamma} irradiation. The fibres were ZrF{sub 4} (and HfF{sub 4}) fibres from different manufacturers, hollow fibres (silica capillaries with internal Ag/AgJ coating) and a sapphire fibre. For the IR range, only the latter fibre type encourages to go further for neutron tests in a reactor. If one restricted the interest onto the near infrared range, high purity core silica fibres could be used. This study might be seen as a typical example of the relation between diagnostic development for a nuclear environment and irradiation experiments.

  20. Fibre-reinforced materials.

    PubMed

    Brown, D

    2000-11-01

    This paper considers the role of fibres in the reinforcement of composite materials, and the significance of the form the fibre takes and the material from which it is made. The current dental applications of fibre reinforcement, including dental cements and splints, fibres made into structures for use in composites, denture bases and the contemporary use of fibres in fixed partial dentures, are reviewed. Their role in biomedical implants is surveyed and their future forecast. PMID:11218597

  1. Nanoporous ultra-high specific surface inorganic fibres

    NASA Astrophysics Data System (ADS)

    Kanehata, Masaki; Ding, Bin; Shiratori, Seimei

    2007-08-01

    Nanoporous inorganic (silica) nanofibres with ultra-high specific surface have been fabricated by electrospinning the blend solutions of poly(vinyl alcohol) (PVA) and colloidal silica nanoparticles, followed by selective removal of the PVA component. The configurations of the composite and inorganic nanofibres were investigated by changing the average silica particle diameters and the concentrations of colloidal silica particles in polymer solutions. After the removal of PVA by calcination, the fibre shape of pure silica particle assembly was maintained. The nanoporous silica fibres were assembled as a porous membrane with a high surface roughness. From the results of Brunauer-Emmett-Teller (BET) measurements, the BET surface area of inorganic silica nanofibrous membranes was increased with the decrease of the particle diameters. The membrane composed of silica particles with diameters of 15 nm showed the largest BET surface area of 270.3 m2 g-1 and total pore volume of 0.66 cm3 g-1. The physical absorption of methylene blue dye molecules by nanoporous silica membranes was examined using UV-vis spectrometry. Additionally, the porous silica membranes modified with fluoroalkylsilane showed super-hydrophobicity due to their porous structures.

  2. Advances in infrared and imaging fibres for astronomical instrumentation

    NASA Astrophysics Data System (ADS)

    Haynes, Roger; McNamara, Pam; Marcel, Jackie; Jovanovic, Nemanja

    2006-06-01

    Optical fibres have already played a huge part in ground based astronomical instrumentation, however, with the revolution in photonics currently taking place new fibre technologies and integrated optical devices are likely to have a profound impact on the way we manipulate light in the future. The Anglo Australian Observatory, along with partners at the Optical Fibre Technology Centre of the University of Sydney, is investigating some of the developing technologies as part of our Astrophotonics programme2. In this paper we discuss the advances that have been made with infrared transmitting fibre, both conventional and microstructured, in particular those based on fluoride glasses. Fluoride glasses have a particularly wide transparent region from the UV through to around 7μm, whereas silica fibres, commonly used in astronomy, only transmit out to about 2μm. We discuss the impact of advances in fibre manufacture that have greatly improved the optical, chemical resistance and physical properties of the fluoride fibres. We also present some encouraging initial test results for a modern imaging fibre bundle and imaging fibre taper.

  3. Flying particle sensors in hollow-core photonic crystal fibre

    NASA Astrophysics Data System (ADS)

    Bykov, D. S.; Schmidt, O. A.; Euser, T. G.; Russell, P. St. J.

    2015-07-01

    Optical fibre sensors make use of diverse physical effects to measure parameters such as strain, temperature and electric field. Here we introduce a new class of reconfigurable fibre sensor, based on a ‘flying-particle’ optically trapped inside a hollow-core photonic crystal fibre and illustrate its use in electric field and temperature sensing with high spatial resolution. The electric field distribution near the surface of a multi-element electrode is measured with a resolution of ∼100 μm by monitoring changes in the transmitted light signal due to the transverse displacement of a charged silica microparticle trapped within the hollow core. Doppler-based velocity measurements are used to map the gas viscosity, and thus the temperature, along a hollow-core photonic crystal fibre. The flying-particle approach represents a new paradigm in fibre sensors, potentially allowing multiple physical quantities to be mapped with high positional accuracy over kilometre-scale distances.

  4. Bismuth-doped germanosilicate fibre laser with 20-W output power at 1460 nm

    SciTech Connect

    Firstov, Sergei V; Shubin, Aleksei V; Khopin, V F; Mel'kumov, Mikhail A; Bufetov, Igor' A; Medvedkov, O I; Gur'yanov, Aleksei N; Dianov, Evgenii M

    2011-07-31

    We report the first cw bismuth - germanium codoped silica fibre laser with an output power above 20 W at 1460 nm and 50% optical efficiency. The laser operates on a transition between energy levels of bismuth-related active centres associated with silicon. The incorporation of a small amount ({approx}5 mol %) of germanium into the core of bismuth-doped silica fibre has little effect on its luminescence spectrum but reduces optical losses, which limit the laser efficiency. (letters)

  5. Effect of optical pumping on the refractive index and temperature in the core of active fibre

    SciTech Connect

    Gainov, V V; Ryabushkin, Oleg A

    2011-09-30

    This paper examines the refractive index change (RIC) induced in the core of Yb{sup 3+}-doped active silica fibres by pulsed pumping. RIC kinetic measurements with a Mach - Zehnder interferometer make it possible to separately assess the contributions of the electronic and thermal mechanisms to the RIC and evaluate temperature nonuniformities in the fibre.

  6. Effect of temperature on the active properties of erbium-doped optical fibres

    NASA Astrophysics Data System (ADS)

    Kotov, L. V.; Ignat'ev, A. D.; Bubnov, M. M.; Likhachev, M. E.

    2016-03-01

    We have studied the effect of heating on the performance of erbium-doped fibre based devices and determined temperaturedependent absorption and emission cross sections of the erbium ion in silica glass. The results demonstrate that heating of fibres in claddingpumped high-power (~100 W) erbium-doped fibre lasers causes no significant decrease in their efficiency. In contrast, superluminescent sources operating in the long-wavelength region (1565 – 1610 nm) are extremely sensitive to temperature changes.

  7. Towards implementation of hollow core fibres for surgical applications

    NASA Astrophysics Data System (ADS)

    Urich, Artur; Delmonte, Tiina; Maier, Robert R. J.; Hand, Duncan P.; Shephard, Jonathan D.

    2011-03-01

    Presently, there is no truly flexible delivery system for light from Er:Yag medical lasers (λ = 2.94 μm) which allows surgeons to work unrestricted. Instead, either a relatively inflexible articulated arm or multi-mode fibre, limited to large bend radii, must be used. One proposed solution is the use of novel types of hollow core - band gap optical fibre rather than more traditional large area solid core fibres. In these silica based fibres, material absorption and damage limitations are overcome by using a photonic band gap structure. This confines radiation to lower order modes, that are guided in a small diameter air core. The overall fibre diameter is also smaller, which allows a smaller mechanical bend radius. Together with the guidance in air, this improves the laser power damage threshold. However, there are many practical hurdles that must be overcome to achieve a robust system for use in surgery. One of the main problems is that the fibre structure is hollow and ingress of dust, vapour, fluids and other contaminants need to be prevented to ensure safe in-vivo usage. Additionally, any infibre contamination will degrade the laser damage resistance of the fibre leading to potential catastrophic failure. The development of a robust and hermetically sealed end cap for the fibre, without adversely affecting beam quality or damage threshold is an essential prerequisite for the safe and efficient use of such fibres in surgery. In this paper we report on the progress on implementing end caps and describe novel methods of sealing off these hollow fibres in particular for surgical applications. This work will demonstrate that the use of these superior fibres with low loss guidance at 2.94 μm in surgery is feasible.

  8. Fibrogenesis by mineral fibres: an in-vitro study of the roles of the macrophage and fibre length.

    PubMed Central

    Aalto, M.; Heppleston, A. G.

    1984-01-01

    Evidence on the mechanism by which inhaled mineral fibres lead to pulmonary fibrosis has not been forthcoming. As with silica, a biphasic cell culture system was required to distinguish phagocytosis from collagen formation. Synthesis of total protein and collagen by rat fibroblasts was estimated by incorporation of labelled proline after treatment with the medium from rat peritoneal macrophages that had been cultured in the presence of different types of mineral fibre. The influence of fibre length was also examined. All the main varieties of asbestos reacted with macrophages to produce or release a fibrogenic factor. However, chrysotile and the longer amosite fibres evoked the response only after prolonging the period of incubation with macrophages, presumably by permitting more complete phagocytosis of curled or longer fibres. Short amosite fibres proved to be more active than longer ones and under certain conditions were as potent as quartz. Fibrous glass also possessed stimulatory properties and again a sample having a short length gave a stronger response than a long one. Collagen formation by asbestos thus appears to be mediated by a macrophage factor, so operating in a manner similar to that previously demonstrated for quartz. The conventional view that short fibres are comparatively insignificant in asbestos fibrogenesis cannot, on the present evidence, be sustained. Furthermore, it should not be assumed than man-made mineral fibres of respirable diameter are innocuous or that short ones can be ignored. PMID:6696832

  9. Therapeutic role of dietary fibre.

    PubMed Central

    Hunt, R.; Fedorak, R.; Frohlich, J.; McLennan, C.; Pavilanis, A.

    1993-01-01

    The current status of dietary fibre and fibre supplements in health and disease is reported, and the components of dietary fibre and its respective mechanical and metabolic effects with emphasis on its therapeutic potential are reviewed. Practical management guidelines are provided to help physicians encourage patients identified as having fibre deficiency to increase dietary fibre intake to the recommended level. PMID:8388284

  10. Fibre optics: Forty years later

    SciTech Connect

    Dianov, Evgenii M

    2010-01-31

    This paper presents a brief overview of the state of the art in fibre optics and its main applications: optical fibre communications, fibre lasers and fibre sensors for various physical property measurements. The future of fibre optics and the status of this important area of the modern technology in Russia are discussed. (fiber optics)

  11. Weaving the invisible thread: design of an optically invisible metamaterial fibre.

    PubMed

    Tuniz, Alessandro; Kuhlmey, Boris T; Chen, Parry Y; Fleming, Simon C

    2010-08-16

    We present the design of an invisible metamaterial fibre operating at optical frequencies, which could be fabricated by adapting existing fibre drawing techniques. The invisibility is realised by matching the refractive index of the metamaterial fibre with the surroundings. We present a general recipe for the fabrication of such fibres, and numerically characterise a specific example using hexagonally arranged silver nanowires in a silica background. We find that invisibility is highly sensitive to details of the metamaterial boundary, a problem that is likely to affect most invisibility and cloaking schemes. PMID:20721197

  12. Numerical simulation of photonic-crystal tellurite-tungstate glass fibres used in parametric fibre devices

    SciTech Connect

    Sokolov, V O; Plotnichenko, V G; Nazaryants, V O; Dianov, Evgenii M

    2006-01-31

    Using the MIT Photonic-Bands Package to calculate fully vectorial definite-mode eigenmodes of Maxwell's equations with periodic boundary conditions in a plane-wave basis, light propagation is simulated in fibres formed by point defects in two-dimensional periodic lattices of cylindrical holes in a glass or of glass tubes. The holes and gaps between tubes are assumed filled with air. Single-site hexagonal and square lattices are considered, which were most often studied both theoretically and experimentally and are used to fabricate silica photonic-crystal fibres. As a defect, a single vacancy is studied - the absent lattice site (one hole in a glass or one of the tubes are filled with the same glass) and a similar vacancy with nearest neighbours representing holes of a larger diameter. The obtained solutions are analysed by the method of effective mode area. The dependences of the effective refractive index and dispersion of the fundamental mode on the geometrical parameters of a fibre are found. The calculations are performed for tellurite-tungstate 80TeO{sub 2}-20WO{sub 3} glass fibres taking into account the frequency dispersion of the refractive index. (optical fibres)

  13. Fibre Flocculation in Papermaking

    NASA Astrophysics Data System (ADS)

    Kerekes, R. J.

    1998-11-01

    Pulp fibres flocculate into aggregates which paper a characteristic non-uniformity on a scale of several millimetres. This non-uniformity, visible in transmitted light, diminishes the physical and optical properties of paper. Consequently, minimization of fibre flocculation has been an objective of papermaking ever since the process was invented. It was established over 50 years ago that mechanical rather than colloidal forces governed fibre flocculation in the shear flows used in papermaking. However, the process by which individual flocs form and the conditions required for their creation have only recently been investigated in detail. This paper will review recent research on this topic at the University of British Columbia. The paper will focus on the formation and properties of coherent flocs, the importance of the Crowding Number in defining the level of interfibre contact necessary for floc creation, the role of hydrodynamic and inter-fibre forces in producing flocs, and the structure and strength of fibre flocs.

  14. Electron irradiation response on Ge and Al-doped SiO 2 optical fibres

    NASA Astrophysics Data System (ADS)

    Yaakob, N. H.; Wagiran, H.; Hossain, I.; Ramli, A. T.; Bradley, D. A.; Hashim, S.; Ali, H.

    2011-05-01

    This paper describes the thermoluminescence response, sensitivity, stability and reproducibility of SiO 2 optical fibres with various electron energies and doses. The TL materials that comprise Al- and Ge-doped silica fibres were used in this experiment. The TL results are compared with those of the commercially available TLD-100. The doped SiO 2 optical fibres and TLD-100 are placed in a solid phantom and irradiated with 6, 9 and 12 MeV electron beams at doses ranging from 0.2 to 4.0 Gy using the LINAC at Hospital Sultan Ismail, Johor Bahru, Malaysia. It was found that the commercially available Al- and Ge-doped optical fibres have a linear dose-TL signal relationship. The intensity of TL response of Ge-doped fibre is markedly greater than that of the Al-doped fibre.

  15. Silica aerogel core waveguide.

    PubMed

    Grogan, M D W; Leon-Saval, S G; England, R; Birks, T A

    2010-10-11

    We have selectively filled the core of hollow photonic crystal fibre with silica aerogel. Light is guided in the aerogel core, with a measured attenuation of 0.2 dB/cm at 1540 nm comparable to that of bulk aerogel. The structure guides light by different mechanisms depending on the wavelength. At long wavelengths the effective index of the microstructured cladding is below the aerogel index of 1.045 and guidance is by total internal reflection. At short wavelengths, where the effective cladding index exceeds 1.045, a photonic bandgap can guide the light instead. There is a small region of crossover, where both index- and bandgap-guided modes were simultaneously observed. PMID:20941148

  16. Holmium fibre laser with record quantum efficiency

    SciTech Connect

    Kurkov, Andrei S; Sholokhov, E M; Tsvetkov, V B; Marakulin, A V; Minashina, L A; Medvedkov, O I; Kosolapov, A F

    2011-06-30

    We report holmium-doped fibre lasers with a Ho{sup 3+} concentration of 1.6 x 10{sup 19} cm{sup -3} and lasing wavelengths of 2.02, 2.05, 2.07 and 2.1 {mu}m at a pump wavelength of 1.15 {mu}m. The slope efficiency of the lasers has been measured. The maximum efficiency, 0.455, has been obtained at a lasing wavelength of 2.05 {mu}m. The laser efficiency is influenced by both the optical loss in the wing of a vibrational absorption band of silica and active-ion clustering. (lasers)

  17. Investigation of sensing properties of microstructured polymer optical fibres

    NASA Astrophysics Data System (ADS)

    Witt, J.; Steffen, M.; Schukar, M.; Krebber, K.

    2010-04-01

    We investigated sensing properties of single mode poly methyl methacrylate (PMMA) microstructured polymer optical fibres (MPOF) with mechanically imprinted long period gratings (LPG). After preparation of the MPOF end-faces the samples were elongated with silica fibres. These samples were used to measure the influence of strain to the LPG wavelength which showed the viscoelastic nature of PMMA. We also measured the influence of temperature and humidity. The results show that MPOF LPGs are well suited for strain sensing. One MPOF LPG was stitched to a textile. Using this textile we measured a simulated respiratory motion.

  18. New generation of optical fibres

    NASA Astrophysics Data System (ADS)

    Dianov, E. M.; Semjonov, S. L.; Bufetov, I. A.

    2016-01-01

    The growing need for information in contemporary society is the motivating force behind the development of fibre optics in general and optical fibre communications in particular. Intensive research effort has been concentrated on designing new types of optical fibres and extending their application field. This paper reviews results of research on new types of optical fibres: bismuthdoped active fibres, multicore fibres and hollow-core fibres, which can be used as key components of systems that ensure further increase in optical information transfer rate.

  19. Silica nephropathy.

    PubMed

    Ghahramani, N

    2010-07-01

    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. PMID:23022796

  20. Integration of conductive reduced graphene oxide into microstructured optical fibres for optoelectronics applications

    NASA Astrophysics Data System (ADS)

    Ruan, Yinlan; Ding, Liyun; Duan, Jingjing; Ebendorff-Heidepriem, Heike; Monro, Tanya M.

    2016-02-01

    Integration of conductive materials into optical fibres can largely expand functions of fibre devices including surface plasmon resonator/metamaterial, modulators/detectors, or biosensors. Some early attempts have been made to incorporate metals such as tin into fibres during the fibre drawing process. Due to the restricted range of materials that have compatible melting temperatures with that of silica glass, the methods to incorporate metals along the length of the fibres are very challenging. Moreover, metals are nontransparent with strong light absorption, which causes high fibre loss. This article demonstrates a novel but simple method for creating transparent conductive reduced graphene oxide film onto microstructured silica fibres for potential optoelectronic applications. The strongly confined evanescent field of the suspended core fibres with only 2 μW average power was creatively used to transform graphene oxide into reduced graphene oxide with negligible additional loss. Existence of reduced graphene oxide was confirmed by their characteristic Raman signals, shifting of their fluorescence peaks as well as largely decreased resistance of the bulk GO film after laser beam exposure.

  1. Integration of conductive reduced graphene oxide into microstructured optical fibres for optoelectronics applications

    PubMed Central

    Ruan, Yinlan; Ding, Liyun; Duan, Jingjing; Ebendorff-Heidepriem, Heike; Monro, Tanya M.

    2016-01-01

    Integration of conductive materials into optical fibres can largely expand functions of fibre devices including surface plasmon resonator/metamaterial, modulators/detectors, or biosensors. Some early attempts have been made to incorporate metals such as tin into fibres during the fibre drawing process. Due to the restricted range of materials that have compatible melting temperatures with that of silica glass, the methods to incorporate metals along the length of the fibres are very challenging. Moreover, metals are nontransparent with strong light absorption, which causes high fibre loss. This article demonstrates a novel but simple method for creating transparent conductive reduced graphene oxide film onto microstructured silica fibres for potential optoelectronic applications. The strongly confined evanescent field of the suspended core fibres with only 2 μW average power was creatively used to transform graphene oxide into reduced graphene oxide with negligible additional loss. Existence of reduced graphene oxide was confirmed by their characteristic Raman signals, shifting of their fluorescence peaks as well as largely decreased resistance of the bulk GO film after laser beam exposure. PMID:26899468

  2. High sensitivity flat SiO2 fibres for medical dosimetry

    NASA Astrophysics Data System (ADS)

    Abdul Sani, Siti. F.; Alalawi, Amani I.; Azhar, Hairul A. R.; Amouzad Mahdiraji, Ghafour; Tamchek, Nizam; Nisbet, A.; Maah, M. J.; Bradley, D. A.

    2014-11-01

    We describe investigation of a novel undoped flat fibre fabricated for medical radiation dosimetry. Using high energy X-ray beams generated at a potential of 6 MV, comparison has been made of the TL yield of silica flat fibres, TLD-100 chips and Ge-doped silica fibres. The flat fibres provide competitive TL yield to that of TLD-100 chips, being some 100 times that of the Ge-doped fibres. Pt-coated flat fibres have then been used to increase photoelectron production and hence local dose deposition, obtaining significant increase in dose sensitivity over that of undoped flat fibres. Using 250 kVp X-ray beams, the TL yield reveals a progressive linear increase in dose for Pt thicknesses from 20 nm up to 80 nm. The dose enhancement factor (DEF) of (0.0150±0.0003) nm-1 Pt is comparable to that obtained using gold, agreeing at the 1% level with the value expected on the basis of photoelectron generation. Finally, X-ray photoelectron spectroscopy (XPS) has been employed to characterize the surface oxidation state of the fibre medium. The charge state of Si2p was found to lie on 103.86 eV of binding energy and the atomic percentage obtained from the XPS analysis is 22.41%.

  3. Integration of conductive reduced graphene oxide into microstructured optical fibres for optoelectronics applications.

    PubMed

    Ruan, Yinlan; Ding, Liyun; Duan, Jingjing; Ebendorff-Heidepriem, Heike; Monro, Tanya M

    2016-01-01

    Integration of conductive materials into optical fibres can largely expand functions of fibre devices including surface plasmon resonator/metamaterial, modulators/detectors, or biosensors. Some early attempts have been made to incorporate metals such as tin into fibres during the fibre drawing process. Due to the restricted range of materials that have compatible melting temperatures with that of silica glass, the methods to incorporate metals along the length of the fibres are very challenging. Moreover, metals are nontransparent with strong light absorption, which causes high fibre loss. This article demonstrates a novel but simple method for creating transparent conductive reduced graphene oxide film onto microstructured silica fibres for potential optoelectronic applications. The strongly confined evanescent field of the suspended core fibres with only 2 μW average power was creatively used to transform graphene oxide into reduced graphene oxide with negligible additional loss. Existence of reduced graphene oxide was confirmed by their characteristic Raman signals, shifting of their fluorescence peaks as well as largely decreased resistance of the bulk GO film after laser beam exposure. PMID:26899468

  4. Fibres get functional

    NASA Astrophysics Data System (ADS)

    Graham-Rowe, Duncan

    2011-02-01

    New forms of advanced optical fibres featuring exotic glasses, carefully designed microstructures and cores that are either hollow, fluidic, semiconductor or piezoelectric are giving light guides a new lease of life, reports Duncan Graham-Rowe.

  5. EDITORIAL: Optical Fibre Sensors 18 (OFS-18)

    NASA Astrophysics Data System (ADS)

    Jones, Julian D. C.; Tatam, Ralph P.

    2007-10-01

    fibre optic gyroscope, conventionally taken to date from the first experimental demonstration by V Vali and R W Shorthill (1976 'Fibre ring interferometer' Appl. Opt. 15 1099-100). It is an indication of the health of the community that the successful maturity of some applications is complemented by the new technologies that will be the basis of the future development of the field, and here the content of this special issue is an interesting indication of likely areas of growth. Essentially all current fibre optic systems are based on solid, doped fused silica fibres, which are the basis of the world's telecommunications industry. However, over the last decade an exciting development has been micro-structured fibres, whose waveguiding properties owe as much to the structure of the fibre as to the materials from which they are made. The significance for sensing applications is considerable, with opportunities to achieve properties for dispersion, environmental sensitivity, wavelength range and power-handling quite different from the capabilities of conventional fibre. Thus it is not surprising that several of the papers in the issue (by Cordeiro, Martynkien, Bock, Wolinski, Michie, Digonnet and Kilic) are devoted to applications of such fibres—photonic crystal fibres (PCF), as they are often called. Digonnet's contribution is especially interesting, being concerned with the use of hollow-core photonic bandgap fibre to form a gyroscope, hence avoiding the many subtle non-linear optical effects that can degrade the performance of a conventional fibre gyroscope. PCF are not the only special fibres to feature in the issue: polymer fibres are of increasing interest for sensing applications (O'Keeffe, Kiesel, Kalli and Ashley), not least for their ability to withstand high levels of strain. In-fibre gratings continue to be a very important area in the field, and are well represented in the issue (Ni, González-Segura, Chen, Falate, Kamikawachi, Wang and Correia). We hope

  6. Binding of bile salts to fibre-enriched wheat fibre.

    PubMed

    Florén, C H; Nilsson, A

    1987-01-01

    A commercial product of fibre-enriched wheat fibre (Fiberform R) was tested for its binding of bile salts in vitro. The wheat fibre preparation was standardized and through enzymatic digestion of protein and starch contained 78 per cent fibre (w/w). Fibre-enriched wheat fibre bound with high capacity both conjugated and unconjugated bile salts. Binding was saturable, reversible and showed no specificity towards tauro- or glycine-conjugated bile salts. Binding was rapid, dependent on pH, was enhanced by the presence of high salt concentrations and partially inhibited by 6 M urea. This indicated that binding was a combination of hydrophobic and hydrophilic interactions. PMID:2820035

  7. Bismuth-doped fibre amplifier for the range 1300 - 1340 nm

    SciTech Connect

    Dianov, Evgenii M; Mel'kumov, Mikhail A; Shubin, Aleksei V; Firstov, Sergei V; Bufetov, Igor' A; Khopin, V F; Gur'yanov, Aleksei N

    2009-12-31

    We demonstrate the first bismuth-doped fibre amplifier operating in the second transmission window of silica-based fibres. At a pump power of 460 mW and pump wavelength of 1230 nm, its gain reaches 24.5 dB at 1320 nm, with a gain bandwidth of 37 nm, saturation power near 10 mW, and noise figure of 5 dB. (letters)

  8. Highly efficient cladding-pumped fibre laser based on an ytterbium-doped optical fibre and a fibre Bragg grating

    SciTech Connect

    Kurkov, Andrei S; Karpov, V I; Medvedkov, O I; Dianov, Evgenii M; Vasil'ev, Sergei A; Paramonov, Vladimir M; Protopopov, V N; Laptev, A Yu; Gur'yanov, A N; Umnikov, A A; Vechkanov, N I; Artyushenko, V G; Frahm, J

    1999-06-30

    Ytterbium-ion-doped double-clad optical fibres were developed. The differential quantum efficiency of a diode-pumped fibre laser, fabricated on the basis of such optical fibres with a fibre Bragg grating, was 90%. (lasers)

  9. Effects of fibre-surface morphology on the mechanical properties of Porifera-inspired rubber-matrix composites

    NASA Astrophysics Data System (ADS)

    Alam, Parvez; Stillfried, Daniela Graf; Celli, Jessika; Toivakka, Martti

    2013-06-01

    In this paper, mineralised organic fibre morphologies, inspired by the structures of Porifera (sponges) are correlated to the mechanical performance of fibre reinforced rubbers. The mineralised structures are rich in calcium carbonate and silica. These compounds nucleate and precipitate on the fibre surfaces yielding different morphologies as a function of mineral ion concentrations. Smaller mineralised precipitates manifestly improve the mechanical performance of composites while thicker precipitates enveloping the fibres give rise to inferior properties. Mechanisms and evidenced reasoning for these differences are reported herein.

  10. Power scaling of Tm-doped fibre lasers using an all-fibre composite Michelson-type cavity

    SciTech Connect

    Yadong Zhu; Zhou, P; Rumao Tao; Xiaolin Wang; Shaofeng Guo; Xiaojun Xu

    2013-09-30

    We report a 4-W all-fibre Tm-doped fibre laser using a composite cavity with a centre wavelength of 1952.02 nm. The composite cavity consists of two interferometric laser arms that are efficiently combined. Each interferometric laser arm contains a double-clad Tm-doped silica fibre operating in cw mode and pumped by pigtailed laser diodes with a centre wavelength of 793 nm. A high combining efficiency of 93.9 % and a narrow linewidth of 0.1 nm are obtained. The output power of the laser can be scaled straight forwardly by improving the pump power and optimising the component parameters at 2 μm (control of laser radiation parameters)

  11. Evaluating distributed fibre optic sensors integrated into thermoplastic composites for structural health monitoring

    NASA Astrophysics Data System (ADS)

    Schilder, Constanze; Schukar, Marcus; Steffen, Milan; Krebber, Katerina

    2014-05-01

    Strain sensors used for structural health monitoring (SHM) must provide reliable measurement data during their entire service lifetime. To achieve this for fibre optic sensors integrated into composites, the integration of the sensor has to be adapted according to the process conditions. This paper describes the fabrication of thermoplastic composite samples with integrated distributed fibre optic sensors (DFOS) based on copper-nickel and polyimide coated silica optical fibres. The performance of these DFOS as SHM sensors is evaluated in terms of reliability by measurements derived from comparative measurements with resistance strain gauges and from fatigue tests with 10 million load cycles.

  12. High-power thulium-doped fibre laser with intracavity dispersion management

    SciTech Connect

    Krylov, Aleksandr A; Chernyshova, M A; Chernykh, D S; Senatorov, A K; Tupitsyn, I M; Kryukov, P G; Dianov, Evgenii M

    2012-05-31

    This paper reports a scheme for the generation and amplification of pico- and femtosecond pulses in the range 1.93-1.97 {mu}m using thulium-doped silica fibres. Group velocity dispersion (GVD) management in the cavity of the thulium-doped fibre laser oscillator is ensured by a single-mode germanosilicate fibre (75 mol % GeO{sub 2} in the core) with a positive GVD. Pulses are obtained down to 200 fs in duration and up to 56 nJ in energy.

  13. Effect of active-ion concentration on holmium fibre laser efficiency

    SciTech Connect

    Kurkov, Andrei S; Sholokhov, E M; Marakulin, A V; Minashina, L A

    2010-08-03

    We have measured the fraction of holmium ions that relax nonradiatively to the ground level as a result of interaction at a metastable level in optical fibres with a silica-based core doped with holmium ions to 2 x 10{sup 19} - 2 x 10{sup 20} cm{sup -3}. The percentage of such ions has been shown to depend on the absolute active-ion concentration. The fibres have been used to make a number of 2.05-{mu}m lasers, and their slope efficiency has been measured. The laser efficiency decreases with increasing holmium concentration in the fibres (lasers)

  14. Optical fibre techniques for use within tamper indicating enclosures designed for arms control verification purposes

    NASA Astrophysics Data System (ADS)

    Dyer, Thomas C.; Thompson, Alexander W. J.; Wynn, Paul; White, Helen

    2014-10-01

    Ensuring that a future nuclear arms control agreement can be verified is a complex technical challenge. Tamper Indicating Enclosures (TIEs) are likely to be deployed as part of a chain of custody regime, providing an indication of an unauthorised attempt to access an item within the agreement. This paper focuses on the assessment of optical fibre techniques for ensuring boundary control as part of a TIE design. The results of optical fibre damage, subsequent repair attempts, enclosure construction considerations and unique identification features have been evaluated for a selection of fused-silica optical fibres. This paper focuses on detecting a fibre repair attempt, presents a method for increasing repair resistance and a method for uniquely identifying an enclosure using the optical signature from the embedded optical fibre.

  15. Advances in CO2 laser fabrication for high power fibre laser devices

    NASA Astrophysics Data System (ADS)

    Boyd, Keiron; Rees, Simon; Simakov, Nikita; Daniel, Jae M. O.; Swain, Robert; Mies, Eric; Hemming, Alexander; Clarkson, W. A.; Haub, John

    2016-03-01

    CO2 laser processing facilitates contamination free, rapid, precise and reproducible fabrication of devices for high power fibre laser applications. We present recent progress in fibre end-face preparation and cladding surface modification techniques. We demonstrate a fine feature CO2 laser process that yields topography significantly smaller than that achieved with typical mechanical cleaving processes. We also investigate the side processing of optical fibres for the fabrication of all-glass cladding light strippers and demonstrate extremely efficient cladding mode removal. We apply both techniques to fibres with complex designs containing multiple layers of doped and un-doped silica as well as shaped and circularly symmetric structures. Finally, we discuss the challenges and approaches to working with various fibre and glass-types.

  16. Development of fibre optic broadband sources at 1 μm region for optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Trifanov, Irina; Berendt, Martin O.; Salcedo, José R.; Podoleanu, Adrian G.; Lobo Ribeiro, António B.

    2008-09-01

    Recent developments on broadband optical sources emitting at 1050 nm wavelength for medical applications, in particular optical coherence tomography (OCT), have revealed enhanced depth penetration into the choroid, reduced scattering losses and improved image performances in eyes with turbid media, when compared to the most commercial used semiconductor optical source technology at 820 nm. In this paper, we present our study of fibre optic broadband sources (BBS) at 1 micron region, based on the amplified spontaneous emission (ASE) from rare-earth doped silica fibres for the integration into OCT systems. The target specifications for this type of sources are: 1050 nm central emission wavelength, with spectral width of ~70 nm, tens of miliwatts of output power and smoothly shaped output spectra. Several combinations of rare-earth doped optical fibres integrated into different fibre optic configurations have been tested. Optical bandwidth optimization and spectral shaping using different fibre optic techniques are presented and their autocorrelation function compared.

  17. Quantum storage of entangled telecom-wavelength photons in an erbium-doped optical fibre

    NASA Astrophysics Data System (ADS)

    Saglamyurek, Erhan; Jin, Jeongwan; Verma, Varun B.; Shaw, Matthew D.; Marsili, Francesco; Nam, Sae Woo; Oblak, Daniel; Tittel, Wolfgang

    2015-02-01

    The realization of a future quantum Internet requires the processing and storage of quantum information at local nodes and interconnecting distant nodes using free-space and fibre-optic links. Quantum memories for light are key elements of such quantum networks. However, to date, neither an atomic quantum memory for non-classical states of light operating at a wavelength compatible with standard telecom fibre infrastructure, nor a fibre-based implementation of a quantum memory, has been reported. Here, we demonstrate the storage and faithful recall of the state of a 1,532 nm wavelength photon entangled with a 795 nm photon, in an ensemble of cryogenically cooled erbium ions doped into a 20-m-long silica fibre, using a photon-echo quantum memory protocol. Despite its currently limited efficiency and storage time, our broadband light-matter interface brings fibre-based quantum networks one step closer to reality.

  18. Polymer optical fibre sensors for endoscopic optoacoustic imaging

    NASA Astrophysics Data System (ADS)

    Broadway, Christian; Gallego, Daniel; Woyessa, Getinet; Pospori, Andreas; Bang, Ole; Webb, David J.; Carpintero, Guillermo; Lamela, Horacio

    2015-07-01

    Opto-acoustic imaging (OAI) shows particular promise for in-vivo biomedical diagnostics. Its applications include cardiovascular, gastrointestinal and urogenital systems imaging. Opto-acoustic endoscopy (OAE) allows the imaging of body parts through cavities permitting entry. The critical parameter is the physical size of the device, allowing compatibility with current technology, while governing flexibility of the distal end of the endoscope based on the needs of the sensor. Polymer optical fibre (POF) presents a novel approach for endoscopic applications and has been positively discussed and compared in existing publications. A great advantage can be obtained for endoscopy due to a small size and array potential to provide discrete imaging speed improvements. Optical fibre exhibits numerous advantages over conventional piezo-electric transducers, such as immunity from electromagnetic interference and a higher resolution at small sizes. Furthermore, micro structured polymer optical fibres offer over 12 times the sensitivity of silica fibre. We present a polymer fibre Bragg grating ultrasound detector with a core diameter of 125 microns. We discuss the ultrasonic signals received and draw conclusions on the opportunities and challenges of applying this technology in biomedical applications.

  19. Enhanced electrochromism in cerium doped molybdenum oxide thin films

    SciTech Connect

    Dhanasankar, M.; Purushothaman, K.K.; Muralidharan, G.

    2010-12-15

    Cerium (5-15% by weight) doped molybdenum oxide thin films have been prepared on FTO coated glass substrate at 250 {sup o}C using sol-gel dip coating method. The structural and morphological changes were observed with the help of XRD, SEM and EDS analysis. The amorphous structure of the Ce doped samples, favours easy intercalation and deintercalation processes. Mo oxide films with 10 wt.% of Ce exhibit maximum anodic diffusion coefficient of 24.99 x 10{sup -11} cm{sup 2}/s and the change in optical transmittance of ({Delta}T at 550 nm) of 79.28% between coloured and bleached state with the optical density of ({Delta}OD) 1.15.

  20. Luminescence of cerium-doped strontium barium niobate

    NASA Astrophysics Data System (ADS)

    Lee, Sun-Kyun; Son, Chang-Won; Chung, Sun-Ju; Tak, Sung-Jun; Lim, Ki-Soo

    2000-10-01

    The broad photoluminescent emission from Ce:Sr0.6Ba0.4Nb2O6 has been observed at 550 nm with excitation in the blue. Photoluminescent excitation spectrum has revealed a trivalent cerium absorption band that is assumed to be a 4f-5d transition. Temperature dependence of the photoluminescence spectra and its lifetimes in 15 - 365 K showed the existence of two different trap centers in the material. We have also investigated the photoluminescence during two-wave mixing experiment to study trap centers.

  1. Role of nitrogen vacancies in cerium doped aluminum nitride

    NASA Astrophysics Data System (ADS)

    Majid, Abdul; Asghar, Farzana; Rana, Usman Ali; Ud-Din Khan, Salah; Yoshiya, Masato; Hussain, Fayyaz; Ahmad, Iftikhar

    2016-08-01

    In this report, a systematic density functional theory based investigation to explain the character of nitrogen vacancies in structural, electronic and magnetic properties of Ce doped wurtzite AlN is presented. The work demonstrates the modification in the properties of the material upon doping thereby addressing dopant concentration and inter-dopant distance. The presence of anionic vacancy reveals spin polarization and introduction of magnetic character in the structure. The doping produced the magnetic character in the material which was of ferromagnetic nature in most cases except the situation when dopants separated by largest distance of 5.873 Å. The calculated values of total energy and exchange energy suggested the configuration including CeAl-VN complex is more favorable and exhibits ferromagnetic ordering.

  2. UV laser induced photochromic centers in cerium doped calcium fluoride

    SciTech Connect

    Pogatshnik, G.J.; Hamilton, D.S.

    1987-01-01

    The optical excitation of the lowest 4f to 5d transition in Ce/sup 3 +/:CaF/sub 2/ by the 308 mm output of a Xe-Cl excimer laser results in strong coloration. The centers created were found to be divalent cerium ions at cubic sites. The system exhibits photochromic properties; the crystal can be returned to the original transparent state by illuminating it with light which is absorbed by the divalent cerium ions. The creation process for these photochromic centers involves a resonant two-photon transition from the 4f ground state of the cerium ion to the conduction band of the CaF/sub 2/ host. The lowest 5d level of the cerium ion serves as the real intermediate state for this transition. The photoionized electron can be trapped by another trivalent cerium ion at a site of cubic symmetry. These impurity sites with O/sub h/ symmetry result when the charge compensator associated with the rare earth ion is somewhat removed from the cerium ion site. The charge compensator is needed to maintain charge neutrality in the crystal when a trivalent rare earth is substituted for a Ca ion in the host lattice. The absence of a local charge compensator at a Ce/sup 3 +/ site with O/sub h/ symmetry, provides a net positive Coulombic potential, which aids in the trapping of electrons from the conduction band. The capture of an electron by a cerium ion at cubic site, changes the valence state of the ion to Ce/sup 2 +/ which accounts for the coloration of the crystal after illumination with uv laser light. A model for the production of the photochromic centers is presented.

  3. EPDM composite membranes modified with cerium doped lead zirconate titanate

    NASA Astrophysics Data System (ADS)

    Zaharescu, T.; Dumitru, A.; Lungulescu, M. E.; Velciu, G.

    2016-01-01

    This study was performed on γ-irradiated ethylene-propylene diene terpolymer (EPDM) loaded with lead zirconate titanate. The inorganic phase has a perovskite structure with general formula Pb(Zr0.65-xCexTi0.35)O3. The three composites with different Ce dopant concentrations revealed the stabilization activity of filler against oxidation proved by chemiluminescence investigation in respect to pristine polymer. The presence of cerium low concentrations in the solid lead zirconate titanate nanoparticles causes significant slowing of oxidation rate during radiation exposure. The improvement in the stabilization feature of filler is correlated with the existence of traps, whose interaction with free radicals assumes medium energy due to their convenient depth.

  4. Fibre-optical microendoscopy.

    PubMed

    Gu, M; Bao, H; Kang, H

    2014-04-01

    Microendoscopy has been an essential tool in exploring micro/nano mechanisms in vivo due to high-quality imaging performance, compact size and flexible movement. The investigations into optical fibres, micro-scanners and miniature lens have boosted efficiencies of remote light delivery to sample site and signal collection. Given the light interaction with materials in the fluorescence imaging regime, this paper reviews two classes of compact microendoscopy based on a single fibre: linear optical microendoscopy and nonlinear optical microendoscopy. Due to the fact that fluorescence occurs only in the focal volume, nonlinear optical microendoscopy can provide stronger optical sectioning ability than linear optical microendoscopy, and is a good candidate for deep tissue imaging. Moreover, one-photon excited fluorescence microendoscopy as the linear optical microendoscopy suffers from severe photobleaching owing to the linear dependence of photobleaching rate on excitation laser power. On the contrary, nonlinear optical microendoscopy, including two-photon excited fluorescence microendoscopy and second harmonic generation microendoscopy, has the capability to minimize or avoid the photobleaching effect at a high excitation power and generate high image contrast. The combination of various nonlinear signals gained by the nonlinear optical microendoscopy provides a comprehensive insight into biophenomena in internal organs. Fibre-optical microendoscopy overcomes physical limitations of traditional microscopy and opens up a new path to achieve early cancer diagnosis and microsurgery in a minimally invasive and localized manner. PMID:24593142

  5. Distributed ultrafast fibre laser

    PubMed Central

    Liu, Xueming; Cui, Yudong; Han, Dongdong; Yao, Xiankun; Sun, Zhipei

    2015-01-01

    A traditional ultrafast fibre laser has a constant cavity length that is independent of the pulse wavelength. The investigation of distributed ultrafast (DUF) lasers is conceptually and technically challenging and of great interest because the laser cavity length and fundamental cavity frequency are changeable based on the wavelength. Here, we propose and demonstrate a DUF fibre laser based on a linearly chirped fibre Bragg grating, where the total cavity length is linearly changeable as a function of the pulse wavelength. The spectral sidebands in DUF lasers are enhanced greatly, including the continuous-wave (CW) and pulse components. We observe that all sidebands of the pulse experience the same round-trip time although they have different round-trip distances and refractive indices. The pulse-shaping of the DUF laser is dominated by the dissipative processes in addition to the phase modulations, which makes our ultrafast laser simple and stable. This laser provides a simple, stable, low-cost, ultrafast-pulsed source with controllable and changeable cavity frequency. PMID:25765454

  6. Is it a modacrylic fibre?

    PubMed

    Grieve, M C; Griffin, R M

    1999-01-01

    This study describes the characteristics of modacrylic fibres and includes over 80 samples (previous and current) representing 15 trade names. Fibre morphology was examined using brightfield microscopy. Signs of elongation were determined using polarised light microscopy. Fibre cross sections were also examined. The generic class of fibre was divided into sub groups using polymer composition as determined by FTIR-microscopy. Microscopically, some modacrylic fibres cannot be distinguished from acrylic fibres. Others display unusual optical and morphological features which are a strong indication of their generic class. The infrared spectra provide information about the co-monomer, termonomers added to produced dye sites, the presence of solvent residue, dyes, and additives, e.g. flame retardant material. The infrared spectra should always be recorded before and after any thin layer chromatographic examination of the dye, otherwise peaks attributable to dyes, which may be a valuable comparative feature in casework will be lost. PMID:10795403

  7. Fibre constituents of some foods.

    PubMed

    Rani, B; Kawatra, A

    1994-06-01

    Some plant foods viz. bottlegourd, carrot, cauliflower, cabbage, green bengalgram, pea, apple, plum, guava, karonda, blackgram husk and lentil husk were analysed for their dietary fibre components. The total dietary fibre contents of these foods varied from 14.68 to 78.21 percent on dry matter basis. As compared to fruits and vegetables, the husks had higher amount of total dietary fibre. Cellulose represented as the major fibre constituent in most of the foods whereas, husks were observed to be good sources of hemicellulose. All foods were low in pectin and lignin contents except guava. PMID:7971775

  8. Simultaneous temperature and humidity measurements in a mechanical ventilator using an optical fibre sensor

    NASA Astrophysics Data System (ADS)

    Hernandez, F. U.; Correia, R.; Morgan, S. P.; Hayes-Gill, B.; Evans, D.; Sinha, R.; Norris, A.; Harvey, D.; Hardman, J. G.; Korposh, S.

    2016-05-01

    An optical fibre sensor for simultaneous temperature and humidity measurements consisting of one fibre Bragg grating (FBG) to measure temperature and a mesoporous film of bilayers of Poly(allylamine hydrochloride)(PAH) and silica (SiO2) nanoparticles deposited onto the tip of the same fibre to measure humidity is reported. The hygroscopic film was created using the layer-by-layer (LbL) method and the optical reflection spectra were measured up to a maximum of 23 bilayers. The temperature sensitivity of the FBG was 10 pm/°C while the sensitivity to humidity was (-1.4x10-12 W / %RH) using 23 bilayers. The developed sensor was tested in the mechanical ventilator and temperature and humidity of the delivered artificial air was simultaneously measured. Once calibrated, the optical fibre sensor has the potential to control the absolute humidity as an essential part of critical respiratory care.

  9. Continuously tunable fibre attenuator operating in the wavelength range near 1.5 {mu}m

    SciTech Connect

    Baum, Ol'ga I; Mishakov, Gennadii V; Sokolov, Viktor I; Varlamova, Nina V; Zapadinskii, Boris I

    2004-09-30

    A fibre attenuator is fabricated for the telecommunication wavelength range near 1.5 {mu}m in which a single-mode silica fibre with side polishing is used. The fibre surface is covered by a layer of fluorine-containing polymer with a large thermooptic coefficient. The principle of attenuator operation is based on a change in the conditions of total internal reflection for a guided mode in the polished region due to thermally induced variation in the refractive index of the fluoropolymer layer. The attenuator is insensitive to light polarisation, it has a continuously variable attenuation coefficient in the range 0.2-27 dB, and can be easily incorporated into fibreoptic links. (fibre optics)

  10. Ultra-short wavelength operation of a thulium fibre laser in the 1660-1750 nm wavelength band.

    PubMed

    Daniel, J M O; Simakov, N; Tokurakawa, M; Ibsen, M; Clarkson, W A

    2015-07-13

    Ultra-short wavelength operation of a thulium fibre laser is investigated. Through use of core pumping and high feedback efficiency wavelength selection, a continuously-tunable fibre laser source operating from 1660 nm to 1720 nm is demonstrated in a silica host. We discuss the range of applications within this important wavelength band such as polymer materials processing and medical applications targeting characteristic C-H bond resonance peaks. As a demonstration of the power scalability of thulium fibre lasers in this band, fixed wavelength operation at 1726 nm with output power up 12.6 W and with slope efficiency > 60% is also shown. PMID:26191883

  11. High-power fibre lasers

    NASA Astrophysics Data System (ADS)

    Jauregui, Cesar; Limpert, Jens; Tünnermann, Andreas

    2013-11-01

    Fibre lasers are now associated with high average powers and very high beam qualities. Both these characteristics are required by many industrial, defence and scientific applications, which explains why fibre lasers have become one of the most popular laser technologies. However, this success, which is largely founded on the outstanding characteristics of fibres as an active medium, has only been achieved through researchers around the world striving to overcome many of the limitations imposed by the fibre architecture. This Review focuses on these limitations, both past and current, and the creative solutions that have been proposed for overcoming them. These solutions have enabled fibre lasers to generate the highest diffraction-limited average power achieved to date by solid-state lasers.

  12. Speciality optical fibres for astronomy

    NASA Astrophysics Data System (ADS)

    Ellis, S. C.; Bland-Hawthorn, J.

    2015-05-01

    Astrophotonics is a rapidly developing area of research which applies photonic technology to astronomical instrumentation. Such technology has the capability of significantly improving the sensitivity, calibration and stability of astronomical instruments, or indeed providing novel capabilities which are not possible using classical optics. We review the development and application of speciality fibres for astronomy, including multi-mode to single-mode converters, notch filters and frequency combs.In particular we focus on our development of instruments designed to filter atmospheric emission lines to enable much deeper spectroscopic observations in the near-infrared. These instruments employ two novel photonic technologies. First, we have developed complex aperiodic fibre Bragg gratings which filter over 100 irregularly spaced wavelengths in a single device, covering a bandwidth of over 200 nm. However, astronomical instruments require highly multi-mode fibres to enable sufficient coupling into the fibre, since atmospheric turbulence heavily distorts the wavefront. But photonic technologies such as fibre Bragg gratings, require single mode fibres. This problem is solved by the photonic lantern, which enables efficient coupling from a multi-mode fibre to an array of single-mode fibres and vice versa. We present the results of laboratory tests of these technologies and of on-sky experiments made using the first instruments to deploy these technologies on a telescope. These tests show that the fibre Bragg gratings suppress the night sky background by a factor of 9. Current instruments are limited by thermal and detector emission. Planned instruments should improve the background suppression even further, by optimising the design of the spectrograph for the properties of the photonic components. Finally we review ongoing research in astrophotonics, including multi-moded multicore fibre Bragg gratings, which enable multiple gratings to be written into the same device

  13. Reticulation des fibres lignocellulosiques

    NASA Astrophysics Data System (ADS)

    Landrevy, Christel

    Pour faire face à la crise économique la conception de papier à valeur ajoutée est développée par les industries papetières. Le but de se projet est l'amélioration des techniques actuelles de réticulation des fibres lignocellulosiques de la pâte à papier visant à produire un papier plus résistant. En effet, lors des réactions de réticulation traditionnelles, de nombreuses liaisons intra-fibres se forment ce qui affecte négativement l'amélioration anticipée des propriétés physiques du papier ou du matériau produit. Pour éviter la formation de ces liaisons intra-fibres, un greffage sur les fibres de groupements ne pouvant pas réagir entre eux est nécessaire. La réticulation des fibres par une réaction de « click chemistry » appelée cycloaddition de Huisgen entre un azide et un alcyne vrai, catalysée par du cuivre (CuAAC) a été l'une des solutions trouvée pour remédier à ce problème. De plus, une adaptation de cette réaction en milieux aqueux pourrait favoriser son utilisation en milieu industriel. L'étude que nous désirons entreprendre lors de ce projet vise à optimiser la réaction de CuAAC et les réactions intermédiaires (propargylation, tosylation et azidation) sur la pâte kraft, en milieu aqueux. Pour cela, les réactions ont été adaptées en milieu aqueux sur la cellulose microcristalline afin de vérifier sa faisabilité, puis transférée à la pâte kraft et l'influence de différents paramètres comme le temps de réaction ou la quantité de réactifs utilisée a été étudiée. Dans un second temps, une étude des différentes propriétés conférées au papier par les réactions a été réalisée à partir d'une série de tests papetiers optiques et physiques. Mots Clés Click chemistry, Huisgen, CuAAC, propargylation, tosylation, azidation, cellulose, pâte kraft, milieu aqueux, papier.

  14. Behaviour of fibre-reinforced high-performance concrete in exterior beam-column joint

    NASA Astrophysics Data System (ADS)

    Muthupriya, P.; Boobalan, S. C.; Vishnuram, B. G.

    2014-09-01

    This paper presents the effect of reinforced high performance concrete (HPC) in exterior beam-column joint with and without fibre under monotonic loading. In this experimental investigation, cross-diagonal bars have been provided at the joint for reducing the congestion of reinforcement in joints, and also M75 grade of concrete with optimum mix proportion of 10 % silica fume and 0.3 % glass fibre was used. Four exterior beam-column joint sub-assemblages were tested. The specimens were divided into two types based on the reinforcement detailing. Type A comprises two joint sub-assemblages with joint detailing as per construction code of practice in India (IS 456-2000), and Type B comprises two joint sub-assemblages with joint detailing as per ductile detailing code of practice in India (IS 13920-1993). In each group there was one specimen of control mix and the remaining one specimen of fibre-reinforced mix. All the test specimens were designed to satisfy the strong column-weak beam concept. The performances of specimens were compared with the control mix and the fibre-reinforced mix. The results show that exterior beam-column joint specimens with silica fume and glass fibre in the HPC mix showed better performance.

  15. Single-Polarisation, Single-Frequency, 2 cm Ytterbium-Doped Fibre Laser

    SciTech Connect

    Guan, W.; Marciante, J.R.

    2007-05-23

    A single-polarisation, single-frequency, ytterbium-doped silica fibre laser has been demonstrated in a 2 cm linear cavity. The output power reaches 35 mW with an optical signal-to-noise ratio greater than 65 dB. A polarisation-maintaining fibre Bragg grating is used as the polarisation-dependent reflector to generate the single-polarisation output with the polarisation extinction ratio greater than 20 dB. The laser works stably for two hours under laboratory conditions.

  16. Use of fibre wastes from production of acetate fibres

    SciTech Connect

    Askarov, M.I.; Tashpulatova, A.B.

    1995-07-01

    The rational use of production wastes is an important part of the Fergana Chemical Fibre Plant in Russia. This recycling reduces the negative effect of the technological process on the environment, increases the economy of production, and produces additional consumer goods. Consumer goods began to be produced at the plant in 1978 with processing of amide-acetate textured fibres into yarn for hand knitting. The need to increase the volumes and expand the variety of goods for the market predetermined an important increase in production of this product. Production of consumer goods has increased since 1990, and both fibre wastes and untreated low-grade fibres and filaments have been used as the starting material. Technological processes for processing wastes and low-grade figured, textured polyamide-acetate fibres into knitting yarn, haberdashery cord, and finishing tape and fringe were created and introduced in subsequent years. The primary technological formulation for production of these materials is well known and is used in light industry. However, production of each type of product in the plant was preceded by research related to selection of the optimum linear density of the filaments used, composition of blends, and the structure of figured fibres, as well as the concrete technological parameters and operating regimes of the equipment to produce articles of the required quality. Development and testing of new decorative textiles are continuing. Low grade and nonstandard acetate semifinished fibre from spinning machines and low grade, bulk dyed acetate fibres have been selected as the raw material for fabrication of these articles.

  17. Radiotherapy dosimetry and the thermoluminescence characteristics of Ge-doped fibres of differing germanium dopant concentration and outer diameter

    NASA Astrophysics Data System (ADS)

    Noor, N. Mohd; Fadzil, M. S. Ahmad; Ung, N. M.; Maah, M. J.; Mahdiraji, G. A.; Abdul-Rashid, H. A.; Bradley, D. A.

    2016-09-01

    We examine the influence of elevated dopant concentration on the thermoluminescence characteristics of novel Ge-doped silica fibres. Basic dosimetric characteristics of the TL media were obtained, including linearity, reproducibility, energy dependence, fading, minimum detectable dose and glow curve analysis, use being made of a 60Co gamma irradiation facility (mean energy 1.25 MeV) and an electron linear accelerator producing photons at an accelerating potential of 6 and 10 MV. The 6 mol% Ge-doped fibres were found to provide TL response superior to that of 8- and 10 mol% Ge-doped fibres, both for fibres with outer diameter of 241 μm and 604 μm. Concerning reproducibility, obtained under three different test conditions, at <10% the 6 mol% Ge dopant concentration was observed to provide the superior coefficient of variation (CV). In regard to energy dependence, the 10 mol% Ge doped cylindrical fibres produced the largest gradient values at 0.364 and 0.327 for the 241 μm and 604 μm diameter cylindrical fibres respectively and thus the greatest energy dependency. Measured 33 days post irradiation; the 6 mol% Ge doped cylindrical fibres showed the least TL signal loss, at 21% for the 241 μm cylindrical fibre and <40% for the 604 μm cylindrical fibres. The results also revealed that the 6 mol% optical fibres provided the lowest minimum detectable dose, at 0.027 Gy for 6 MV photon beams. Evaluations of these characteristics are supporting development of novel Ge-doped optical fibres for dosimetry in radiotherapy.

  18. Electrical percolation of fibre mixtures

    NASA Astrophysics Data System (ADS)

    Xie, Juan; Gordon, Stuart; Long, Hairu; Miao, Menghe

    2015-11-01

    In the development of conductive threads for wearable electronics, nonconductive cotton fibres and conductive stainless steel fibres are mixed to produce composite yarns at a wide range of stainless steel fibre weight fractions. The electrical resistance of the composite yarns is measured at different probe span lengths, ranging from 0.5 to 10 L ss ( L ss = 50 mm is the average length of stainless steel fibres). The percolation threshold and critical exponent are determined for each span length. The critical exponent followed a decreasing trend from 1.87 to 1.17 as the span length was increased. When the conductive fibre loading was expressed in terms of conductive fibre volume fraction, the percolation critical exponent showed a similar trend of change with probe span length. Such a dependence of percolation critical exponent on resistance probe span length has not been previously reported for conductive particle-filled polymer composites, probably because the probe span length used in resistance measurement is orders of magnitude larger than the dimension of the conductive fillers in the composites.

  19. Multifunctional mesoporous silica catalyst

    DOEpatents

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

    2015-03-31

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

  20. What Is Crystalline Silica?

    MedlinePlus

    ... silica, and requires a repirator protection program until engineering controls are implemented. Additionally, OSHA has a National ... silica materials with safer substitutes, whenever possible. ■ Provide engineering or administrative controls, where feasible, such as local ...

  1. Silica extraction from geothermal water

    SciTech Connect

    Bourcier, William L; Bruton, Carol J

    2014-09-23

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

  2. Study on the Sensing Coating of the Optical Fibre CO2 Sensor

    PubMed Central

    Wysokiński, Karol; Napierała, Marek; Stańczyk, Tomasz; Lipiński, Stanisław; Nasiłowski, Tomasz

    2015-01-01

    Optical fibre carbon dioxide (CO2) sensors are reported in this article. The principle of operation of the sensors relies on the absorption of light transmitted through the fibre by a silica gel coating containing active dyes, including methyl red, thymol blue and phenol red. Stability of the sensor has been investigated for the first time for an absorption based CO2 optical fiber sensor. Influence of the silica gel coating thickness on the sensitivity and response time has also been studied. The impact of temperature and humidity on the sensor performance has been examined too. Response times of reported sensors are very short and reach 2–3 s, whereas the sensitivity of the sensor ranges from 3 to 10 for different coating thicknesses. Reported parameters make the sensor suitable for indoor and industrial use. PMID:26694412

  3. Gamma irradiated thermoluminescence response of Ge-doped SiO2 fibre.

    PubMed

    Wahib, Norfadira; Zulkepely, Nurul Najua; Mat Nawi, Siti Nurasiah; Amin, Yusoff Mohd; Ling, Yap Seong; Abdul Sani, Siti Fairus; Maah, Mohd Jamil; Bradley, D A

    2015-11-01

    Over the past decade and more, considerable interest has been shown in the thermoluminescence (TL) properties of silica-based single-mode optical fibres, in particular investigating potential ionising radiation dosimetry applications. Herein, study has been made of TL glow curve, dose response, reproducibility and fading of 6mol% Ge-doped silica, fabricated in-house and produced in the form of cylindrical fibres. Three different pairings of doped-core and silica cladding diameters were produced: (40, 241)µm, (80, 483)µm and (100, 604)µm. The TL results were compared against that of TLD-100, one of the most sensitive commercially available LiF-based TL media. For all three pairings of diameters, closely similar TL glow curve were obtained, formed of a single peaked structure with a maximum TL yield located between the temperatures 250 and 310°C. The TL yield of the fibres were linear over the range of doses investigated, from 1Gy up to 10Gy, their dose response exceeding that of TLD-100, the samples also being found to be reusable, without evidence of degradation. PMID:26313622

  4. A high-energy fibre-to-fibre connection for direct optical initiation systems

    NASA Astrophysics Data System (ADS)

    Bowden, M. D.; Knowles, S. L.

    2012-11-01

    Direct Optical Initiation (DOI), uses a moderate energy laser to shock initiate secondary explosives, via either a flyer plate or exploding metal foil. DOI offers significant performance and safety advantages over conventional electrical initiation. Optical fibres are used to transport the optical energy from the laser to the explosive device. A DOI system comprises of a laser, one or more optical fibres, and one or more laser detonators. Realisation of a DOI system is greatly eased by the use of fibre-to-fibre connections, allowing for easy integration into bulkheads or other interfaces, such as firing tanks and environmental test chambers. Fibres to fibre connectors capable of transmitting the required energy densities are not commercially available. Energy densities in the region of 35 J cm-2 are required for initiation, above the damage threshold of typical optical fibres. Laser-induced damage is typically caused by laser absorption at the input face due to imperfections in the surface polishing. To successfully transmit energy densities for DOI, a high quality fibre end face finish is required. A fibre-to-fibre connection utilizing micro-lens array injection into a large-core, tapered optical fibre, a hermetic fibre bulkhead feedthrough, and a disposable test fibre has been developed. This permits easy connection of test detonators or components, with the complex free-space to fibre injection simplified to a single operation. The damage threshold and transmission losses of the fibre-to-fibre connection have been established for each interface.

  5. Moderate-power cw fibre lasers

    SciTech Connect

    Kurkov, Andrei S; Dianov, Evgenii M

    2004-10-31

    A review of the development and investigation of moderate-power (10{sup -1}-10{sup 2} W) cw fibre lasers is presented. The properties of optical fibres doped with rare-earth ions and methods for fabricating double-clad fibres are considered. The methods for fabrication of fibre Bragg gratings used as selective reflectors are discussed and the grating properties are analysed. The main pump schemes for double-clad fibre lasers are described. The properties of fibre lasers doped with neodymium, ytterbium, erbium, thulium, and holmium ions are also considered. The principles of fabrication of Raman converters of laser radiation based on optical fibres of different compositions are discussed and the main results of their studies are presented. It is concluded that fibre lasers described in the review can produce moderate-power radiation at any wavelength in the spectral range from 0.9 to 2 {mu}m. (review)

  6. LHCb Upgrade: Scintillating Fibre Tracker

    NASA Astrophysics Data System (ADS)

    Tobin, Mark

    2016-07-01

    The LHCb detector will be upgraded during the Long Shutdown 2 (LS2) of the LHC in order to cope with higher instantaneous luminosities and to read out the data at 40 MHz using a trigger-less read-out system. All front-end electronics will be replaced and several sub-detectors must be redesigned to cope with higher occupancy. The current tracking detectors downstream of the LHCb dipole magnet will be replaced by the Scintillating Fibre (SciFi) Tracker. The SciFi Tracker will use scintillating fibres read out by Silicon Photomultipliers (SiPMs). State-of-the-art multi-channel SiPM arrays are being developed to read out the fibres and a custom ASIC will be used to digitise the signals from the SiPMs. The evolution of the design since the Technical Design Report in 2014 and the latest R & D results are presented.

  7. Dietary fibre and cardiovascular health.

    PubMed

    Sánchez-Muniz, F J

    2012-01-01

    Cardiovascular disease (CVD) is the leading cause of mortality and morbidity in developed countries. CVD is an inflammatory disease associated with risk factors that include hypercholesterolemia and hypertension. Furthermore, the evolution of this disease depends on the amount of modified lipoproteins (e.g. oxidized) present in the arterial subendothelium. Diet is considered the cornerstone for CVD treatment, as it can lower not only atherogenic lipoprotein levels and degree of oxidation, but also blood pressure, thrombogenesis and concentrations of some relevant factors (e.g. homocystein).Among different diets, the Mediterranean diet stands out due to their benefits on several health benefits, in particular with regard to CVD. Rich in vegetable foods, this diet contributes both quantitatively and qualitatively to essential fibre compounds (cellulose, hemicellulose, gums, mucilages, pectins, oligosaccharides, lignins, etc.). The present paper analyzes the effects of fibre consumption on a) cholesterol and lipoprotein levels; b) systolic and diastolic blood pressures; and c) antioxidant availability and profile. Some studies and meta-analysis are revised, as the possible mechanisms by which fibre may decrease plasma total cholesterol and LDL-cholesterol and blood pressure and to act as antioxidant, as well. In addition, author's own publications regarding the effect of fibre matrix (e.g. seaweeds) on arylesterase and the gene expression of some key antioxidant enzymes are reviewed. The paper also includes data concerning the possible interaction between fibre and some hypolipemic drugs, which may make it possible to attain similar hypolipemic effects with lower dosages, with the consequent decrease in possible side effects. The review concludes with a summary of nutritional objectives related to the consumption of carbohydrates and fibre supplements. PMID:22566302

  8. Portable smartphone optical fibre spectrometer

    NASA Astrophysics Data System (ADS)

    Hossain, Md. Arafat; Canning, John; Cook, Kevin; Jamalipour, Abbas

    2015-09-01

    A low cost, optical fibre based spectrometer has been developed on a smartphone platform for field-portable spectral analysis. Light of visible wavelength is collected using a multimode optical fibre and diffracted by a low cost nanoimprinted diffraction grating. A measurement range over 300 nm span (λ = 400 to 700 nm) is obtained using the smartphone CMOS chip. The spectral resolution is Δλ ~ 0.42 nm/screen pixel. A customized Android application processed the spectra on the same platform and shares with other devices. The results compare well with commercially available spectrometer.

  9. Liquid crystal assisted optical fibres.

    PubMed

    Wahle, M; Kitzerow, H-S

    2014-01-13

    Microstructured fibres which consist of a circular step index core and a liquid crystal inclusion running parallel to this core are investigated. The attenuation and electro-optic effects of light coupled into the core are measured. Coupled mode theory is used to study the interaction of core modes with the liquid crystal inclusion. The experimental and theoretical results show that these fibres can exhibit attenuation below 0.16 dB cm(-1) in off-resonant wavelength regions and still have significant electro-optic effects which can lead to a polarisation extinction of 6 dB cm(-1). PMID:24514987

  10. Friction and wear of human hair fibres

    NASA Astrophysics Data System (ADS)

    Bowen, James; Johnson, Simon A.; Avery, Andrew R.; Adams, Michael J.

    2016-06-01

    An experimental study of the tribological properties of hair fibres is reported, and the effect of surface treatment on the evolution of friction and wear during sliding. Specifically, orthogonally crossed fibre/fibre contacts under a compressive normal load over a series of 10 000 cycle studies are investigated. Reciprocating sliding at a velocity of 0.4 mm s‑1, over a track length of 0.8 mm, was performed at 18 °C and 40%–50% relative humidity. Hair fibres retaining their natural sebum were studied, as well as those stripped of their sebum via hexane cleaning, and hair fibres conditioned using a commercially available product. Surface topography modifications resulting from wear were imaged using scanning electron microscopy and quantified using white light interferometry. Hair fibres that presented sebum or conditioned product at the fibre/fibre junction exhibited initial coefficients of friction at least 25% lower than those that were cleaned with hexane. Coefficients of friction were observed to depend on the directionality of sliding for hexane cleaned hair fibres after sufficient wear cycles that cuticle lifting was present, typically on the order 1000 cycles. Cuticle flattening was observed for fibre/fibre junctions exposed to 10 mN compressive normal loads, whereas loads of 100 mN introduced substantial cuticle wear and fibre damage.

  11. Silica-Ceria Hybrid Nanostructures

    SciTech Connect

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

    2012-04-25

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

  12. A fibre-optic mode-filtered light sensor for general and fast chemical assay

    NASA Astrophysics Data System (ADS)

    Zhou, Leiji; Wang, Kemin; Choi, Martin M. F.; Xiao, Dan; Yang, Xiaohai; Chen, Rui; Tan, Weihong

    2004-01-01

    A simple and fast-response fibre-optic chemical sensor based on mode-filtered light detection (MFLD) has been successfully developed. The sensor was constructed by inserting an unmodified fibre core into a silica capillary tubing; a charge-coupled device which acted as a multi-channel detector was positioned alongside the capillary to detect the emanated mode-filtered light. An interesting finding was observed: there was an increase in the signal upon the decrease in the sample refractive index when an unclad optical fibre was employed, which was different from the results of a polymer-clad fibre reported previously. This phenomenon of opposite signal trend can clearly be interpreted by applying a mathematical derivation based on light propagation in the optical fibre. The derived mathematical model correlates well with the experimental results. It also provides a good theoretical foundation for the future development of MFLD-based analyser in conjunction with liquid chromatographic separation and assay. The proposed MFLD sensor was successfully applied to determine acetic acid with a linear response in the range 0-90 v/v % and a correlation coefficient of 0.9959. The sensor has the advantages of high S/N ratio and very fast response time. It offers the potential for use as a general sensor in food and chemical industries.

  13. Silazane to silica

    NASA Technical Reports Server (NTRS)

    Harvey, Gale A.

    1992-01-01

    Thin film silica and/or methyl silicone were detected on most external surfaces of the retrieved LDEF. Known sources of silicone in or on the LDEF appear inadequate to explain the ubiquitous presence of the silica and silicone films. Hexamethyldisilazane (HMDS) was used as the Challenger tile waterproofing compound for the Challenger/LDEF deployment mission. HMDS releases NH3 which depolymerizes silicone RTV's. Polyurethanes were also attacked. Much of the silica/silicone contamination of LDEF resulted from HMDS.

  14. Intrafusal muscle fibre types in frog spindles.

    PubMed Central

    Diwan, F H; Ito, F

    1989-01-01

    Muscle spindles from bullfrog semitendinosus, iliofibularis and sartorius muscles were examined with light and electron microscopy. Four types of intrafusal muscle fibre were identified according to their diameter, central nucleation and reticular zone arrangement: a large nuclear bag fibre, a medium nuclear bag fibre, and two types of small nuclear chain fibres with and without a reticular zone, respectively. It is suggested that they are comparable to the nuclear bag1, bag2 and chain fibres in mammalian muscle spindles. Images Fig. 7 PMID:2532636

  15. Muscle fibre type changes in hypothyroid myopathy.

    PubMed Central

    McKeran, R O; Slavin, G; Andrews, T M; Ward, P; Mair, W G

    1975-01-01

    Changes in muscle fibre type in hypothyroid myopathy were studied by serial percutaneous needle biopsy of vastus lateralis before and during treatment with L-thyroxine. A type II fibre atrophy and loss was found, which correlated with the clinical and biochemical evidence of a myopathy. The type II fibre atrophy was corrected by L-thyroxine but type II fibre loss was still apparent in severely myopathic patients up to two years after starting treatment. The pathogenesis and significance of type II fibre atrophy and loss are discussed in relation to prognosis. PMID:1184764

  16. Fibre ring cavity semiconductor laser

    SciTech Connect

    Duraev, V P; Medvedev, S V

    2013-10-31

    This paper presents a study of semiconductor lasers having a polarisation maintaining fibre ring cavity. We examine the operating principle and report main characteristics of a semiconductor ring laser, in particular in single- and multiple-frequency regimes, and discuss its application areas. (lasers)

  17. Silazine to silica

    NASA Technical Reports Server (NTRS)

    Harvey, Gale A.

    1993-01-01

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

  18. Assessment of exposure to quartz, cristobalite and silicon carbide fibres (whiskers) in a silicon carbide plant.

    PubMed

    Dion, Chantal; Dufresne, André; Jacob, Marcel; Perrault, Guy

    2005-06-01

    The main objective of the present paper is to report on the concentration of silicon carbide (SiC) fibres, crystalline silica and respirable dust in a Canadian SiC production plant and to compare the results with earlier investigations. The second objective is to tentatively explain the differences in concentration of the fibrogenic substances between different countries. The assessment of SiC fibres, dusts, respirable quartz and cristobalite was performed according to standard procedures. The highest 8 h time-weighted average concentrations of fibres were found among the crusher and backhoe attendants and the carboselectors with an arithmetic mean of 0.63 fibres ml(-1) for the former group and 0.51 fibres ml(-1) for the latter group. The results of respirable SiC fibres in the Canadian plant were lower than in the Norwegian and Italian industries. Most of the 8 h time-weighted average concentrations for quartz were less than or around the limit of detection of 0.01 mg m(-3). The maximum 8 h time-weighted average concentration for quartz was found among the carboselectors (0.157 mg m(-3)), followed by the labourers (0.032 mg m(-3)). Similarly, most of the 8 h time-weighted average cristobalite measurements were less than the limit of detection of 0.01 mg m(-3) except for the carboselectors where it was found to be 0.044 mg m(-3). The assessment of the Italian occupational settings exposure demonstrated elevated quartz concentrations, while cristobalite was absent. The authors have concluded that the investigations that were performed in the last two decades in this field by researchers from different countries seem to support that SiC fibres (whiskers) constitute a major airborne health hazard. PMID:15650014

  19. Relation between lung asbestos fibre burden and exposure indices based on job history.

    PubMed Central

    Takahashi, K; Case, B W; Dufresne, A; Fraser, R; Higashi, T; Siemiatycki, J

    1994-01-01

    Lung asbestos burden was compared with exposure indices derived from job history interviews in 42 male subjects originating from the Montréal Case-Control Study project, 12 of whom had documented asbestos exposed job histories. Job interview data consisting of a chronological timetable of job histories were translated into detailed exposure indices by an expert group of hygienists and chemists. Total and individual asbestos fibre type concentrations were quantified by transmission electron microscopy with fibre identification by energy dispersive chi ray spectrometry after deparaffinisation of tissue blocks and low temperature plasma ashing. Geometric mean or median asbestos content was higher in subjects with an asbestos exposed job history than those without for retained dose of amosite, total commercial amphiboles, and total asbestos fibre. Except for crocidolite fibre diameter, which was significantly less in the lungs of exposed workers, no consistent differences were found in measurements of fibre dimension for any fibre type. Subgroups of subjects exposed to silica, metals, or smokers and non-smokers without significant occupational exposure showed varying patterns of lung asbestos fibre type deficit compared with the asbestos exposed subgroup. There was an overall trend for higher lung asbestos content proportional to higher exposure indices for asbestos representing concentration, frequency, and reliability. These exposure indices as well as duration of exposure (in years) were independent predictors of total asbestos content in regression analyses when combined in a model with age. Stepwise regression indicated that exposure concentration was the most important variable, explaining 32% of the total variation in total asbestos content. Smoking, whether expressed in ever or never smoked dichotomy or in smoked-years, had no relation to lung asbestos content in this model. PMID:8044245

  20. Advanced Fibre Bragg Grating and Microfibre Bragg Grating Fabrication Techniques

    NASA Astrophysics Data System (ADS)

    Chung, Kit Man

    Fibre Bragg gratings (FBGs) have become a very important technology for communication systems and fibre optic sensing. Typically, FBGs are less than 10-mm long and are fabricated using fused silica uniform phase masks which become more expensive for longer length or non-uniform pitch. Generally, interference UV laser beams are employed to make long or complex FBGs, and this technique introduces critical precision and control issues. In this work, we demonstrate an advanced FBG fabrication system that enables the writing of long and complex gratings in optical fibres with virtually any apodisation profile, local phase and Bragg wavelength using a novel optical design in which the incident angles of two UV beams onto an optical fibre can be adjusted simultaneously by moving just one optical component, instead of two optics employed in earlier configurations, to vary the grating pitch. The key advantage of the grating fabrication system is that complex gratings can be fabricated by controlling the linear movements of two translation stages. In addition to the study of advanced grating fabrication technique, we also focus on the inscription of FBGs written in optical fibres with a cladding diameter of several ten's of microns. Fabrication of microfibres was investigated using a sophisticated tapering method. We also proposed a simple but practical technique to filter out the higher order modes reflected from the FBG written in microfibres via a linear taper region while the fundamental mode re-couples to the core. By using this technique, reflection from the microfibre Bragg grating (MFBG) can be effectively single mode, simplifying the demultiplexing and demodulation processes. MFBG exhibits high sensitivity to contact force and an MFBG-based force sensor was also constructed and tested to investigate their suitability for use as an invasive surgery device. Performance of the contact force sensor packaged in a conforming elastomer material compares favourably to one

  1. Silica, Silicosis, and Autoimmunity

    PubMed Central

    Pollard, Kenneth Michael

    2016-01-01

    Inhalation of dust containing crystalline silica is associated with a number of acute and chronic diseases including systemic autoimmune diseases. Evidence for the link with autoimmune disease comes from epidemiological studies linking occupational exposure to crystalline silica dust with the systemic autoimmune diseases systemic lupus erythematosus, systemic sclerosis, and rheumatoid arthritis. Although little is known regarding the mechanism by which silica exposure leads to systemic autoimmune disease, there is a voluminous literature on silica exposure and silicosis that may help identify immune processes that precede development of autoimmunity. The pathophysiology of silicosis consists of deposition of silica particles in the alveoli of the lung. Ingestion of these particles by macrophages initiates an inflammatory response, which stimulates fibroblasts to proliferate and produce collagen. Silica particles are encased by collagen leading to fibrosis and the nodular lesions characteristic of the disease. The steps in the development of silicosis, including acute and chronic inflammation and fibrosis, have different molecular and cellular requirements, suggesting that silica-induced inflammation and fibrosis may be mechanistically separate. Significantly, it is unclear whether silica-induced inflammation and fibrosis contribute similarly to the development of autoimmunity. Nonetheless, the findings from human and animal model studies are consistent with an autoimmune pathogenesis that begins with activation of the innate immune system leading to proinflammatory cytokine production, pulmonary inflammation leading to activation of adaptive immunity, breaking of tolerance, and autoantibodies and tissue damage. The variable frequency of these immunological features following silica exposure suggests substantial genetic involvement and gene/environment interaction in silica-induced autoimmunity. However, numerous questions remain unanswered. PMID:27014276

  2. Silica, Silicosis, and Autoimmunity.

    PubMed

    Pollard, Kenneth Michael

    2016-01-01

    Inhalation of dust containing crystalline silica is associated with a number of acute and chronic diseases including systemic autoimmune diseases. Evidence for the link with autoimmune disease comes from epidemiological studies linking occupational exposure to crystalline silica dust with the systemic autoimmune diseases systemic lupus erythematosus, systemic sclerosis, and rheumatoid arthritis. Although little is known regarding the mechanism by which silica exposure leads to systemic autoimmune disease, there is a voluminous literature on silica exposure and silicosis that may help identify immune processes that precede development of autoimmunity. The pathophysiology of silicosis consists of deposition of silica particles in the alveoli of the lung. Ingestion of these particles by macrophages initiates an inflammatory response, which stimulates fibroblasts to proliferate and produce collagen. Silica particles are encased by collagen leading to fibrosis and the nodular lesions characteristic of the disease. The steps in the development of silicosis, including acute and chronic inflammation and fibrosis, have different molecular and cellular requirements, suggesting that silica-induced inflammation and fibrosis may be mechanistically separate. Significantly, it is unclear whether silica-induced inflammation and fibrosis contribute similarly to the development of autoimmunity. Nonetheless, the findings from human and animal model studies are consistent with an autoimmune pathogenesis that begins with activation of the innate immune system leading to proinflammatory cytokine production, pulmonary inflammation leading to activation of adaptive immunity, breaking of tolerance, and autoantibodies and tissue damage. The variable frequency of these immunological features following silica exposure suggests substantial genetic involvement and gene/environment interaction in silica-induced autoimmunity. However, numerous questions remain unanswered. PMID:27014276

  3. Materials growth and processing in the capillaries of photonic crystal fibres: towards the lab-in-a-fibre protocol

    NASA Astrophysics Data System (ADS)

    Konidakis, Ioannis; Konstantaki, Maria; Pissadakis, Stavros

    2014-03-01

    We review results on the growth of glassy and crystalline materials inside photonics crystal fibres (PCFs), seeking specific sensing and light confining properties. Initial results refer to the infiltration of silver metaphosphate (AgPO3) glass inside PCFs, and the subsequent thermal poling of those composite PCFs for attaining plasmon resonance characteristics. Accordingly, the wet chemistry growth and characterization of crystalline ZnO layers inside PCFs is shown also. Finally, the use of laser etching technique for the inscription of relief periodic Bragg gratings on the capillary walls of a solid core, all silica glass PCF that exhibited demarcation temperatures near 1200 °C is presented. Ongoing work refers to the exploitation of the aforementioned PCFs for developing sensing, bio-sensing and actuating optofluidic devices.

  4. Application of silica nanoparticles for increased silica availability in maize

    NASA Astrophysics Data System (ADS)

    Suriyaprabha, R.; Karunakaran, G.; Yuvakkumar, R.; Prabu, P.; Rajendran, V.; Kannan, N.

    2013-02-01

    Silica nanoparticles were extracted from rice husk and characterised comprehensively. The synthesised silica powders were amorphous in size with 99.7% purity (20-40 nm). Nanosilica was amended with red soil at 15 kg ha-1 along with micron silica. The influence of nanoscale on silica uptake, accumulation and nutritional variations in maize roots were evaluated through the studies such as root sectioning, elemental analysis and physiological parameters (root length and silica content) and compared with micron silica and control. Nanosilica treated soil reveals enhanced silica uptake and elongated roots which make the plant to resist in stress conditions like drought.

  5. New antifouling silica hydrogel.

    PubMed

    Beltrán-Osuna, Ángela A; Cao, Bin; Cheng, Gang; Jana, Sadhan C; Espe, Matthew P; Lama, Bimala

    2012-06-26

    In this work, a new antifouling silica hydrogel was developed for potential biomedical applications. A zwitterionic polymer, poly(carboxybetaine methacrylate) (pCBMA), was produced via atom-transfer radical polymerization and was appended to the hydrogel network in a two-step acid-base-catalyzed sol-gel process. The pCBMA silica aerogels were obtained by drying the hydrogels under supercritical conditions using CO(2). To understand the effect of pCBMA on the gel structure, pCBMA silica aerogels with different pCBMA contents were characterized using scanning electron microscopy (SEM), nuclear magnetic resonance (NMR) spectroscopy, and the surface area from Brauner-Emmet-Teller (BET) measurements. The antifouling property of pCBMA silica hydrogel to resist protein (fibrinogen) adsorption was measured using enzyme-linked immunosorbent assay (ELISA). SEM images revealed that the particle size and porosity of the silica network decreased at low pCBMA content and increased at above 33 wt % of the polymer. The presence of pCBMA increased the surface area of the material by 91% at a polymer content of 25 wt %. NMR results confirmed that pCBMA was incorporated completely into the silica structure at a polymer content below 20 wt %. A protein adsorption test revealed a reduction in fibrinogen adsorption by 83% at 25 wt % pCBMA content in the hydrogel compared to the fibrinogen adsorption in the unmodified silica hydrogel. PMID:22607091

  6. Silicon-core glass fibres as microwire radial-junction solar cells

    NASA Astrophysics Data System (ADS)

    Martinsen, F. A.; Smeltzer, B. K.; Nord, M.; Hawkins, T.; Ballato, J.; Gibson, U. J.

    2014-09-01

    Vertically aligned radial-junction solar cell designs offer potential improvements over planar geometries, as carrier generation occurs close to the junction for all absorption depths, but most production methods still require a single crystal substrate. Here, we report on the fabrication of such solar cells from polycrystalline, low purity (99.98%) p-type silicon starting material, formed into silicon core, silica sheath fibres using bulk glass draw techniques. Short segments were cut from the fibres, and the silica was etched from one side, which exposed the core and formed a conical cavity around it. We then used vapour deposition techniques to create p-i-n junction solar cells. Prototype cells formed from single fibres have shown conversion efficiencies up to 3.6%, despite the low purity of the starting material. This fabrication method has the potential to reduce the energy cost and the silicon volume required for solar cell production. Simulations were performed to investigate the potential of the conical cavity around the silicon core for light collection. Absorption of over 90% of the incident light was predicted, over a wide range of wavelengths, using these structures in combination with a 10% volume fraction of silicon.

  7. Ytterbium-doped fibre laser with a Bragg grating reflector written in a multimode fibre

    SciTech Connect

    Kurkov, Andrei S; Grukh, Dmitrii A; Medvedkov, O I; Paramonov, Vladimir M; Dianov, Evgenii M

    2005-04-30

    An efficient cladding-pumped Yb-doped fibre laser with a Bragg grating written in a multimode graded-index fibre is fabricated for the first time. The laser emits one transverse mode with a slope efficiency of 60%. The resonator design proposed in the paper can be used for the development of high-power fibre lasers with an increased fibre core diameter. (lasers)

  8. OPTICAL FIBRES AND FIBREOPTIC SENSORS: Polarisation reflectometry of anisotropic optical fibres

    NASA Astrophysics Data System (ADS)

    Konstantinov, Yurii A.; Kryukov, Igor'I.; Pervadchuk, Vladimir P.; Toroshin, Andrei Yu

    2009-11-01

    Anisotropic, polarisation-maintaining fibres have been studied using a reflectometer and integrated optic polariser. Linearly polarised pulses were launched into the fibre under test at different angles between their plane of polarisation and the main optical axis of the fibre. A special procedure for the correlation analysis of these reflectograms is developed to enhance the reliability of the information about the longitudinal optical uniformity ofanisotropic fibres.

  9. Scintillating Fibre Tracking at High Luminosity Colliders

    NASA Astrophysics Data System (ADS)

    Joram, C.; Haefeli, G.; Leverington, B.

    2015-08-01

    The combination of small diameter scintillating plastic fibres with arrays of SiPM photodetectors has led to a new class of SciFi trackers usable at high luminosity collider experiments. After a short review of the main principles and history of the scintillating fibre technology, we describe the challenges and developments of the large area Scintillating Fibre Tracker currently under development for the upgraded LHCb experiment.

  10. Silica Embedded Metal Hydrides

    SciTech Connect

    Heung, L.K.; Wicks, G.G.

    1998-08-01

    A method to produce silica embedded metal hydride was developed. The product is a composite in which metal hydride particles are embedded in a matrix of silica. The silica matrix is highly porous. Hydrogen gas can easily reach the embedded metal hydride particles. The pores are small so that the metal hydride particles cannot leave the matrix. The porous matrix also protects the metal hydride particles from larger and reactive molecules such as oxygen, since the larger gas molecules cannot pass through the small pores easily. Tests show that granules of this composite can absorb hydrogen readily and withstand many cycles without making fines.

  11. Oxygen configurations in silica

    SciTech Connect

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

    2000-07-15

    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{sub 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.

  12. Towards the Knittability of Graphene Oxide Fibres.

    PubMed

    Seyedin, Shayan; Romano, Mark S; Minett, Andrew I; Razal, Joselito M

    2015-01-01

    Recent developments in graphene oxide fibre (GO) processing include exciting demonstrations of hand woven textile structures. However, it is uncertain whether the fibres produced can meet the processing requirements of conventional textile manufacturing. This work reports for the first time the production of highly flexible and tough GO fibres that can be knitted using textile machinery. The GO fibres are made by using a dry-jet wet-spinning method, which allows drawing of the spinning solution (the GO dispersion) in several stages of the fibre spinning process. The coagulation composition and spinning conditions are evaluated in detail, which led to the production of densely packed fibres with near-circular cross-sections and highly ordered GO domains. The results are knittable GO fibres with Young's modulus of ~7.9 GPa, tensile strength of ~135.8 MPa, breaking strain of ~5.9%, and toughness of ~5.7 MJ m(-3). The combination of suitable spinning method, coagulation composition, and spinning conditions led to GO fibres with remarkable toughness; the key factor in their successful knitting. This work highlights important progress in realising the full potential of GO fibres as a new class of textile. PMID:26459866

  13. Local dynamics for fibred holomorphic transformations

    NASA Astrophysics Data System (ADS)

    Ponce, Mario

    2007-12-01

    Fibred holomorphic dynamics are skew-product transformations F(θ, z) = (θ + α, fθ(z)) over an irrational rotation, such that fθ is holomorphic for every θ. In this paper we study such a dynamics in a neighbourhood of an invariant curve. We obtain some results analogous to the results in the non-fibred case. In particular, we prove a fibred version of the folklore result stating that Lyapounov stability is equivalent to linearization around a fixed point. We also obtain a fibred version of the Pérez-Marco continua.

  14. Towards the Knittability of Graphene Oxide Fibres

    PubMed Central

    Seyedin, Shayan; Romano, Mark S.; Minett, Andrew I.; Razal, Joselito M.

    2015-01-01

    Recent developments in graphene oxide fibre (GO) processing include exciting demonstrations of hand woven textile structures. However, it is uncertain whether the fibres produced can meet the processing requirements of conventional textile manufacturing. This work reports for the first time the production of highly flexible and tough GO fibres that can be knitted using textile machinery. The GO fibres are made by using a dry-jet wet-spinning method, which allows drawing of the spinning solution (the GO dispersion) in several stages of the fibre spinning process. The coagulation composition and spinning conditions are evaluated in detail, which led to the production of densely packed fibres with near-circular cross-sections and highly ordered GO domains. The results are knittable GO fibres with Young’s modulus of ~7.9 GPa, tensile strength of ~135.8 MPa, breaking strain of ~5.9%, and toughness of ~5.7 MJ m−3. The combination of suitable spinning method, coagulation composition, and spinning conditions led to GO fibres with remarkable toughness; the key factor in their successful knitting. This work highlights important progress in realising the full potential of GO fibres as a new class of textile. PMID:26459866

  15. Modelling skeletal muscle fibre orientation arrangement.

    PubMed

    Lu, Y T; Zhu, H X; Richmond, S; Middleton, J

    2011-12-01

    Skeletal muscle tissues have complex geometries. In addition, the complex fibre orientation arrangement makes it quite difficult to create an accurate finite element muscle model. There are many possible ways to specify the complex fibre orientations in a finite element model, for example defining a local element coordinate system. In this paper, an alternative method using ABAQUS, which is combination of the finite element method and the non-uniform rational B-spline solid representation, is proposed to calculate the initial fibre orientations. The initial direction of each muscle fibre is specified as the tangent direction of the NURBS curve which the fibre lies on, and the directions of the deformed fibres are calculated from the initial fibre directions, the deformation gradients and the fibre stretch ratios. Several examples are presented to demonstrate the ability of the proposed method. Results show that the proposed method is able to characterise both the muscle complex fibre orientation arrangement and its complex mechanical response. PMID:20924862

  16. Towards the Knittability of Graphene Oxide Fibres

    NASA Astrophysics Data System (ADS)

    Seyedin, Shayan; Romano, Mark S.; Minett, Andrew I.; Razal, Joselito M.

    2015-10-01

    Recent developments in graphene oxide fibre (GO) processing include exciting demonstrations of hand woven textile structures. However, it is uncertain whether the fibres produced can meet the processing requirements of conventional textile manufacturing. This work reports for the first time the production of highly flexible and tough GO fibres that can be knitted using textile machinery. The GO fibres are made by using a dry-jet wet-spinning method, which allows drawing of the spinning solution (the GO dispersion) in several stages of the fibre spinning process. The coagulation composition and spinning conditions are evaluated in detail, which led to the production of densely packed fibres with near-circular cross-sections and highly ordered GO domains. The results are knittable GO fibres with Young’s modulus of ~7.9 GPa, tensile strength of ~135.8 MPa, breaking strain of ~5.9%, and toughness of ~5.7 MJ m-3. The combination of suitable spinning method, coagulation composition, and spinning conditions led to GO fibres with remarkable toughness; the key factor in their successful knitting. This work highlights important progress in realising the full potential of GO fibres as a new class of textile.

  17. A validation of the fibre orientation and fibre length attrition prediction for long fibre-reinforced thermoplastics

    SciTech Connect

    Hopmann, Ch.; Weber, M.; Haag, J. van; Schöngart, M.

    2015-05-22

    To improve the mechanical performance of polymeric parts, fibre reinforcement has established in industrial applications during the last decades. Next to the widely used Short Fibre-reinforced Thermoplastics (SFT) the use of Long Fibre-reinforced Thermoplastics (LFT) is increasingly growing. Especially for non-polar polymeric matrices like polypropylene (PP), longer fibres can significantly improve the mechanical performance. As with every kind of discontinuous fibre reinforcement the fibre orientations (FO) show a high impact on the mechanical properties. On the contrary to SFT where the local fibre length distribution (FLD) can be often neglected, for LFT the FLD show a high impact on the material’s properties and has to be taken into account in equal measure to the FOD. Recently numerical models are available in commercial filling simulation software and allow predicting both the local FOD and FLD in LFT parts. The aim of this paper is to compare i.) the FOD results and ii) the FLD results from available orientation- and fibre length attrition-models to those obtained from experimental data. The investigations are conducted by the use of different injection moulded specimens made from long glass fibre reinforced PP. In order to determine the FOD, selected part sections are examined by means of Computed Tomographic (CT) analyses. The fully three dimensional measurement of the FOD is then performed by digital image processing using grey scale correlation. The FLD results are also obtained by using digital image processing after a thermal pyrolytic separation of the polymeric matrix from the fibres. Further the FOD and the FLD are predicted by using a reduced strain closure (RSC) as well as an anisotropic rotary diffusion - reduced strain closure model (ARD-RSC) and Phelps-Tucker fibre length attrition model implemented in the commercial filling software Moldflow, Autodesk Inc., San Rafael, CA, USA.

  18. A validation of the fibre orientation and fibre length attrition prediction for long fibre-reinforced thermoplastics

    NASA Astrophysics Data System (ADS)

    Hopmann, Ch.; Weber, M.; van Haag, J.; Schöngart, M.

    2015-05-01

    To improve the mechanical performance of polymeric parts, fibre reinforcement has established in industrial applications during the last decades. Next to the widely used Short Fibre-reinforced Thermoplastics (SFT) the use of Long Fibre-reinforced Thermoplastics (LFT) is increasingly growing. Especially for non-polar polymeric matrices like polypropylene (PP), longer fibres can significantly improve the mechanical performance. As with every kind of discontinuous fibre reinforcement the fibre orientations (FO) show a high impact on the mechanical properties. On the contrary to SFT where the local fibre length distribution (FLD) can be often neglected, for LFT the FLD show a high impact on the material's properties and has to be taken into account in equal measure to the FOD. Recently numerical models are available in commercial filling simulation software and allow predicting both the local FOD and FLD in LFT parts. The aim of this paper is to compare i.) the FOD results and ii) the FLD results from available orientation- and fibre length attrition-models to those obtained from experimental data. The investigations are conducted by the use of different injection moulded specimens made from long glass fibre reinforced PP. In order to determine the FOD, selected part sections are examined by means of Computed Tomographic (CT) analyses. The fully three dimensional measurement of the FOD is then performed by digital image processing using grey scale correlation. The FLD results are also obtained by using digital image processing after a thermal pyrolytic separation of the polymeric matrix from the fibres. Further the FOD and the FLD are predicted by using a reduced strain closure (RSC) as well as an anisotropic rotary diffusion - reduced strain closure model (ARD-RSC) and Phelps-Tucker fibre length attrition model implemented in the commercial filling software Moldflow, Autodesk Inc., San Rafael, CA, USA.

  19. Ultra-wide bandwidth wavelength selective couplers based on the all solid multi-core Ge-doped fibre

    NASA Astrophysics Data System (ADS)

    Li, X.; Sun, B.; Yu, Y.

    2014-09-01

    A novel wavelength selective coupler based on the all solid nine-core Ge-doped fibre has been proposed. The wavelength selective coupler is based on the phenomenon of a multi-core coupling. All the cores are made of Ge-doped silica and the index of central core is larger than the outer core. At the fixed fibre length, the different wavelength can be selected. The performances of coupling and propagation characteristics have been numerically investigated by using a full beam propagation method (BPM). Simulation results show that the all solid nine-core Ge-doped fibre can achieve simultaneous shorter coupler length and wideband filtering characteristics. The 0.763 mm and 0.745 mm wavelength selective coupler are proposed to achieve different wavelength division and the bandwidth is up to the 400 nm, and 300 nm, respectively.

  20. Surface treated polypropylene (PP) fibres for reinforced concrete

    SciTech Connect

    López-Buendía, Angel M.; Romero-Sánchez, María Dolores; Climent, Verónica

    2013-12-15

    Surface treatments on a polypropylene (PP) fibre have contributed to the improvement of fibre/concrete adhesion in fibre-reinforced concrete. The treatments to the PP fibre were characterized by contact angle measurements, ATR-IR and XPS to analyse chemical alterations. The surface topography and fibre/concrete interaction were analysed by several microscopic techniques, namely optical petrographic, and scanning electron microscopy. Treatment modified the surface chemistry and topography of the fibre by introducing sodium moieties and created additional fibre surface roughness. Modifications in the fibre surface led to an increase in the adhesion properties between the treated fibres and concrete and an improvement in the mechanical properties of the fibre-reinforced concrete composite as compared to the concrete containing untreated PP fibres. Compatibility with the concrete and increased roughness and mineral surface was also improved by nucleated portlandite and ettringite mineral association anchored on the alkaline PP fibre surface, which is induced during treatment.

  1. Cellulose-silica aerogels.

    PubMed

    Demilecamps, Arnaud; Beauger, Christian; Hildenbrand, Claudia; Rigacci, Arnaud; Budtova, Tatiana

    2015-05-20

    Aerogels based on interpenetrated cellulose-silica networks were prepared and characterised. Wet coagulated cellulose was impregnated with silica phase, polyethoxydisiloxane, using two methods: (i) molecular diffusion and (ii) forced flow induced by pressure difference. The latter allowed an enormous decrease in the impregnation times, by almost three orders of magnitude, for a sample with the same geometry. In both cases, nanostructured silica gel was in situ formed inside cellulose matrix. Nitrogen adsorption analysis revealed an almost threefold increase in pores specific surface area, from cellulose aerogel alone to organic-inorganic composite. Morphology, thermal conductivity and mechanical properties under uniaxial compression were investigated. Thermal conductivity of composite aerogels was lower than that of cellulose aerogel due to the formation of superinsulating mesoporous silica inside cellulose pores. Furthermore, composite aerogels were stiffer than each of reference aerogels. PMID:25817671

  2. Crystalline Silica Primer

    USGS Publications Warehouse

    Staff- Branch of Industrial Minerals

    1992-01-01

    substance and will present a nontechnical overview of the techniques used to measure crystalline silica. Because this primer is meant to be a starting point for anyone interested in learning more about crystalline silica, a list of selected readings and other resources is included. The detailed glossary, which defines many terms that are beyond the scope of this publication, is designed to help the reader move from this presentation to a more technical one, the inevitable next step.

  3. Silica, hybrid silica, hydride silica and non-silica stationary phases for liquid chromatography.

    PubMed

    Borges, Endler M

    2015-04-01

    Free silanols on the surface of silica are the "villains", which are responsible for detrimental interactions of those compounds and the stationary phase (i.e., bad peak shape, low efficiency) as well as low thermal and chemical stability. For these reasons, we began this review describing new silica and hybrid silica stationary phases, which have reduced and/or shielded silanols. At present, in liquid chromatography for the majority of analyses, reversed-phase liquid chromatography is the separation mode of choice. However, the needs for increased selectivity and increased retention of hydrophilic bases have substantially increased the interest in hydrophilic interaction chromatography (HILIC). Therefore, stationary phases and this mode of separation are discussed. Then, non-silica stationary phases (i.e., zirconium oxide, titanium oxide, alumina and porous graphitized carbon), which afford increased thermal and chemical stability and also selectivity different from those obtained with silica and hybrid silica, are discussed. In addition, the use of these materials in HILIC is also reviewed. PMID:25234386

  4. Simulation of complex phenomena in optical fibres

    NASA Astrophysics Data System (ADS)

    Allington-Smith, Jeremy; Murray, Graham; Lemke, Ulrike

    2012-12-01

    Optical fibres are essential for many types of highly multiplexed and precision spectroscopy. The success of the new generation of multifibre instruments under construction to investigate fundamental problems in cosmology, such as the nature of dark energy, requires accurate modellization of the fibre system to achieve their signal-to-noise ratio (SNR) goals. Despite their simple construction, fibres exhibit unexpected behaviour including non-conservation of etendue (focal ratio degradation, FRD) and modal noise. Furthermore, new fibre geometries (non-circular or tapered) have become available to improve the scrambling properties that, together with modal noise, limit the achievable SNR in precision spectroscopy. These issues have often been addressed by extensive tests on candidate fibres and their terminations, but these are difficult and time-consuming. Modelling by ray tracing and wave analysis is possible with commercial software packages, but these do not address the more complex features, in particular FRD. We use a phase-tracking ray-tracing method to provide a practical description of FRD derived from our previous experimental work on circular fibres and apply it to non-standard fibres. This allows the relationship between scrambling and FRD to be quantified for the first time. We find that scrambling primarily affects the shape of the near-field pattern but has negligible effect on the barycentre. FRD helps to homogenize the near-field pattern but does not make it completely uniform. Fibres with polygonal cross-section improve scrambling without amplifying the FRD. Elliptical fibres, in conjunction with tapering, may offer an efficient means of image slicing to improve the product of resolving power and throughput, but the result is sensitive to the details of illumination. We also investigated the performance of fibres close to the limiting numerical aperture since this may affect the uniformity of the SNR for some prime focus fibre instrumentation.

  5. Polarisation effects in twin-core fibre: Application for mode locking in a fibre laser

    SciTech Connect

    Lobach, I A; Kablukov, S I; Podivilov, Evgenii V; Babin, Sergei A; Apolonski, A A

    2012-09-30

    We report the first measurements of the longitudinal power distribution in a twin-core optical fibre at different input light polarisations. Experimental evidence is presented that, because of the difference in birefringence between the cores, the power in them depends on which core the beam is launched into. Experimental data are interpreted in terms of a modified polarisation model for mode coupling in twin-core fibres which takes into account the birefringence of the cores. In addition, we demonstrate for the first time the use of the polarisation properties of a twincore fibre for mode locking in a fibre laser. (optical fibres, lasers and amplifiers. properties and applications)

  6. Image analysis of insulation mineral fibres.

    PubMed

    Talbot, H; Lee, T; Jeulin, D; Hanton, D; Hobbs, L W

    2000-12-01

    We present two methods for measuring the diameter and length of man-made vitreous fibres based on the automated image analysis of scanning electron microscopy images. The fibres we want to measure are used in materials such as glass wool, which in turn are used for thermal and acoustic insulation. The measurement of the diameters and lengths of these fibres is used by the glass wool industry for quality control purposes. To obtain reliable quality estimators, the measurement of several hundred images is necessary. These measurements are usually obtained manually by operators. Manual measurements, although reliable when performed by skilled operators, are slow due to the need for the operators to rest often to retain their ability to spot faint fibres on noisy backgrounds. Moreover, the task of measuring thousands of fibres every day, even with the help of semi-automated image analysis systems, is dull and repetitive. The need for an automated procedure which could replace manual measurements is quite real. For each of the two methods that we propose to accomplish this task, we present the sample preparation, the microscope setting and the image analysis algorithms used for the segmentation of the fibres and for their measurement. We also show how a statistical analysis of the results can alleviate most measurement biases, and how we can estimate the true distribution of fibre lengths by diameter class by measuring only the lengths of the fibres visible in the field of view. PMID:11106965

  7. Supercontinuum generation in thulium-doped fibres

    SciTech Connect

    Kurkov, Andrei S; Kamynin, V A; Tsvetkov, V B; Sadovnikova, Ya E; Marakulin, A V; Minashina, L A

    2012-09-30

    Supercontinuum generation in thulium-doped fibres under pumping at 1.59 {mu}m is investigated. Amplification of supercontinuum in the range of 1.8--2.0 {mu}m is found for a fibre doped to a level of 2 Multiplication-Sign 10{sup 19} cm{sup -3}. For a fibre with an activator concentration of 2 Multiplication-Sign 10{sup 20} cm{sup -3} amplification is also observed in the (2.1 - 2.45)-{mu}m band, which suggests the occurrence of the {sup 3}H{sub 4} {yields} {sup 3}H{sub 5} optical transition in the fibre. The occupation of the {sup 3}H{sub 4} level can be explained by cooperative effects. (optical fibres, lasers and amplifiers. properties and applications)

  8. All-fibre pulsed digital holography

    NASA Astrophysics Data System (ADS)

    Schedin, Staffan; Pedrini, Giancarlo; Tiziani, Hans J.; Santoyo, Fernando Mendoza

    1999-07-01

    An all-fibre optic system was used to record pulsed digital holograms of objects undergoing static and dynamic deformations. Light from a pulsed ruby laser was divided in two beams, each launched through different optical fibres. One fibre carried the object beam illumination and the other conveyed the reference beam towards the detector of a CCD camera. Laser light scattered from the object surface was collected with a lens-optical fibre endoscope arrangement and combined at the CCD detector with the reference beam. The holograms thus formed were digitally recorded for static and dynamic conditions. For data evaluation the Fourier transform method was used. Results show phase maps that may be evaluated for static and dynamic object deformation. With the use of a pulsed laser, the all-fibre system presented here may find a number of useful applications outside the laboratory in areas such as micromechanics, microelectronics and medical endoscopy, where access to objects of interest is otherwise difficult.

  9. Self-sensing E-glass fibres

    NASA Astrophysics Data System (ADS)

    Kister, G.; Wang, L.; Ralph, B.; Fernando, G. F.

    2003-02-01

    The primary aims of this study were to demonstrate that conventional reinforcing E-glass fibres could be converted to act as waveguides. This was achieved by selecting and applying appropriate cladding material onto the glass fibre bundle. Three classes of cladding materials were evaluated: epoxy, polyurethane and sol-gel. The light transmission characteristics through the E-glass waveguides was evaluated and compared. The epoxy and polyurethane cladding were found to be superior compared to the sol-gel coated fibres in terms of the quality of the coating and the light transmission intensity over specified lengths. The effect of fibre-end preparation on the light transmission characteristic was also investigated. The feasibility of conducting in situ tensile tests where the light transmission intensity was passed through the E-glass fibres was demonstrated successfully. This in situ technique was capable of highlighting differences in the macroscopic tensile failure modes obtained using the various cladding materials.

  10. Fibre-Matrix Interaction in Soft Tissue

    SciTech Connect

    Guo, Zaoyang

    2010-05-21

    Although the mechanical behaviour of soft tissue has been extensively studied, the interaction between the collagen fibres and the ground matrix has not been well understood and is therefore ignored by most constitutive models of soft tissue. In this paper, the human annulus fibrosus is used as an example and the potential fibre-matrix interaction is identified by careful investigation of the experimental results of biaxial and uniaxial testing of the human annulus fibrosus. First, the uniaxial testing result of the HAF along the axial direction is analysed and it is shown that the mechanical behaviour of the ground matrix can be well simulated by the incompressible neo-Hookean model when the collagen fibres are all under contraction. If the collagen fibres are stretched, the response of the ground matrix can still be described by the incompressible neo-Hookean model, but the effective stiffness of the matrix depends on the fibre stretch ratio. This stiffness can be more than 10 times larger than the one obtained with collagen fibres under contraction. This phenomenon can only be explained by the fibre-matrix interaction. Furthermore, we find that the physical interpretation of this interaction includes the inhomogeneity of the soft tissue and the fibre orientation dispersion. The dependence of the tangent stiffness of the matrix on the first invariant of the deformation tensor can also be explained by the fibre orientation dispersion. The significant effect of the fibre-matrix interaction strain energy on mechanical behaviour of the soft tissue is also illustrated by comparing some simulation results.

  11. Smart medical textiles with embedded optical fibre sensors for continuous monitoring of respiratory movements during MRI

    NASA Astrophysics Data System (ADS)

    Witt, J.; Narbonneau, F.; Schukar, M.; Krebber, K.; De Jonckheere, J.; Jeanne, M.; Kinet, D.; Paquet, B.; Depré, A.; D'Angelo, L. T.; Thiel, T.; Logier, R.

    2010-09-01

    We report on three respiration sensors based on pure optical technologies developed during the FP6 EU project OFSETH. The developed smart medical textiles can sense elongation up to 3%, while maintaining the stretching properties of the textile substrates for a good comfort of the patient. The sensors, based on silica and polymer fibre, are developed for monitoring of patients during MRI examination. The OFSETH harness allows a continuous measurement of respiration movements while all vitals organs are free for medical staff actions. The sensors were tested in MRI environment and on healthy adults.

  12. Kinetics of silica polymerization

    SciTech Connect

    Weres, O.; Yee, A.; Tsao, L.

    1980-05-01

    The polymerization of silicic acid in geothermal brine-like aqueous solutions to produce amorphous silica in colloidal form has been studied experimentally and theoretically. A large amount of high quality experimental data has been generated over the temperature rang 23 to 100{sup 0}C. Wide ranges of dissolved silica concentration, pH, and sodium chloride concentration were covered. The catalytic effects of fluoride and the reaction inhibiting effects of aluminum and boron were studied also. Two basic processes have been separately studied: the formation of new colloidal particles by the homogeneous nucleation process and the deposition of dissolved silica on pre-existing colloidal particles. A rigorous theory of the formation of colloidal particles of amorphous silica by homogeneous nucleation was developed. This theory employs the Lothe-Pound formalism, and is embodied in the computer code SILNUC which quantitatively models the homogeneous nucleation and growth of colloidal silica particles in more than enough detail for practical application. The theory and code were extensively used in planning the experimental work and analyzing the data produced. The code is now complete and running in its final form. It is capable of reproducing most of the experimental results to within experimental error. It is also capable of extrapolation to experimentally inaccessible conditions, i.e., high temperatures, rapidly varying temperature and pH, etc.

  13. Silica in alkaline brines

    USGS Publications Warehouse

    Jones, B.F.; Rettig, S.L.; Eugster, H.P.

    1967-01-01

    Analysis of sodium carbonate-bicarbonate brines from closed basins in volcanic terranes of Oregon and Kenya reveals silica contents of up to 2700 parts per million at pH's higher than 10. These high concentrations of SiO 2 can be attributed to reaction of waters with silicates, and subsequent evaporative concentration accompanied by a rise in pH. Supersaturation with respect to amorphous silica may occur and persist for brines that are out of contact with silicate muds and undersaturated with respect to trona; correlation of SiO2 with concentration of Na and total CO2 support this interpretation. Addition of moredilute waters to alkaline brines may lower the pH and cause inorganic precipitation of substantial amounts of silica.

  14. Silica Precipitation and Lithium Sorption

    SciTech Connect

    Jay Renew

    2015-09-20

    This file contains silica precipitation and lithium sorption data from the project. The silica removal data is corrected from the previous submission. The previous submission did not take into account the limit of detection of the ICP-MS procedure.

  15. Vortex shedding fluid flowmeter using optical fibre sensor

    NASA Astrophysics Data System (ADS)

    Lyle, J. H.; Pitt, C. W.

    1981-03-01

    An optical fibre flowmeter is described which uses a single fibre mounted transversely to the fluid flow within the pipe. The fibre is vibrated by the natural phenomenon of vortex shedding, causing phase modulation of the optical carrier within. The modulation is detected at the fibre exit by the fibredyne technique, and the flow rate determined from the vibration frequency.

  16. Small fibre function in primary autonomic failure.

    PubMed

    Baron, R; Feldmann, R; Lindner, V

    1993-12-01

    A case of primary autonomic failure (AF) with uncomplicated Parkinson's disease is presented with clinical and neurophysiological data. Special emphasis is placed on new methods of examining impairment of unmyelinated sympathetic and afferent C-fibres. Sympathetic vasoconstrictor responses in the skin induced by deep inspiration were examined quantitatively with laser Doppler flowmetry. The vasoconstriction was markedly depressed in primary AF compared with healthy controls and similar to secondary forms of AF. Peripheral nociceptive C-fibre function was quantitatively assessed by measurement of axon reflex vasodilatation induced by histamine iontophoresis. The axon reflex vasodilatation was completely intact in primary AF in contrast to patients with secondary peripheral small fibre neuropathy. The results indicate that sympathetic C-fibres are considerably affected by the degenerative disease, whereas the afferent C-fibres seem to be totally preserved. Modern neurophysiological methods of testing sympathetic and afferent small fibre function in combination with other neurophysiological tests, e.g. brain-stem auditory evoked potentials, might help to diagnose and differentiate primary AF in early stages and make it easier to distinguish between secondary autonomic neuropathies of unknown origin that often also involve unmyelinated afferent fibres. PMID:8138830

  17. Chalcogenide-tellurite composite microstructured optical fibre

    NASA Astrophysics Data System (ADS)

    Kohoutek, T.; Duan, Z.; Kawashima, H.; Yan, X.; Suzuki, T.; Matsumoto, M.; Misumi, Takashi; Ohishi, Y.

    2012-02-01

    We report on fabrication a composite microstructured optical fibre composed of highly nonlinear chalcogenide Ge-Ga- Sb-S glass core and tellurite TeO2-ZnO-Li20-Bi2O3 glass clad. We aimed at obtaining more flattened chromatic dispersion for pumping chalcogenide glass based optical fibre by a pulse laser at current telecommunication wavelengths, i.e. λ = 1.35 - 1.7 μm, which is difficult to achieve by using a single material chalcogenide fibers due to their high refractive index (n > 2.1). A fibre design exploiting a composite of two glasses and one ring of the air holes brings similar options for tuning the fibre dispersion such as use of complex multi rings of air-holes approach. A good choice of glasses, allows for fabricating a composite chalcogenide-tellurite optical fibre benefiting from high nonlinearity of chalcogenide core glass but exploiting a tellurite glass technology and fibre drawing. In the paper, we discuss some aspects of CMOF design concerning current chalcogenide and tellurite glass choice. Also, we show the supercontinuum spectra recorded from current chalcogenide-tellurite CMOF pumped with a custom made femtosecond fibre laser at λ = 1.55 μm with the pulse duration of 400 fs.

  18. Epoxy Grout With Silica Thickener

    NASA Technical Reports Server (NTRS)

    Mcclung, C. E.

    1984-01-01

    Grout cures quickly, even in presence of hydraulic oil. Grout is mixture of aggregate particles, finely-divided silica, epoxy resin, and triethylenetetramine curing agent, with mixture containing about 85 percent silica and aggregate particle sand 15 percent resin and curing agent. Silica is thickening agent and keeps grout from sagging.

  19. Ge and B doped collapsed photonic crystal optical fibre, a potential TLD material for low dose measurements

    NASA Astrophysics Data System (ADS)

    Rozaila, Z. Siti; Alyahyawi, Amjad; Khandaker, M. U.; Amin, Y. M.; Bradley, D. A.; Maah, M. J.

    2016-09-01

    Offering a number of advantageous features, tailor-made silica-based fibres are attracting attention as thermoluminesence (TL) dosimeters. We have performed a detailed study of the TL properties of Ge-doped and Ge-B-doped collapsed photonic crystal fibres (PCFc), most particularly with regard to their potential use for the environmental and X-ray diagnostic dose monitoring. Extrinsic doping and defects generated by strain at the fused inner walls of the collapsed fibres result in the PCFc-Ge-B and PCFc-Ge fibres producing markedly greater TL response than that of the phosphor-based dosimeter TLD-100, by some 9 and 7×, respectively. The linearity of TL yield has been investigated for X-ray doses from 0.5 mGy to 10 mGy. For a dose of 1 Gy, the energy response of the PCFs and TLD-100 has been studied using X-rays generated at accelerating potentials from 20 kVp through to 200 kVp and for the 1.25 MeV mean gamma-ray energy from 60Co. The effective atomic number , Zeffof PCFc-Ge and PCFc-Ge-B was estimated to be 12.5 and 14.4, respectively. Some 35 days post-irradiation, fading of the stored TL signal from PCFc-Ge-B and PCFc-Ge were found to be ∼15% and 20% respectively, with mean loss in TL emission of 0.4-0.5% per day. The present doped-silica collapsed PCFs provide greatly improved TLD performance compared to that of previous fibre designs and phosphor-based TLD-100.

  20. Intraocular tissue ablation using an optical fibre to deliver the 5th harmonic of a Nd:YAG

    NASA Astrophysics Data System (ADS)

    Miller, Joseph; Yu, Xiaobo; Yu, Paula K.; Cringle, Stephen J.; Yu, Dao-Yi

    2009-02-01

    We report the evaluation of a system which delivers the 5th harmonic of an Nd:YAG (213nm) via optical fibre to ocular tissue sites. The 213nm beam is concentrated, using a hollow glass taper, prior to launch into 200 μm or 600 μm core diameter silica/silica optical fibre. The fibre tip was tapered to enhance the fluence delivered. An operating window of fluence values that could be delivered via 330 - 1100mm lengths of optical fibre was determined. The lower value of 0.2J/cm2 determined by the ablation threshold of the tissue and the upper value of 1.3J/cm2 by the launch, transmission and tip characteristics of the optical fibre. The fluence output decreased as a function of both transmitted pulse energy and number of pulses transmitted. Fresh retinal tissue was cleanly ablated with minimal damage to the surrounding tissue. Lesions were generated using 1, 3 and 10 pulses with fluences from 0.2 to 1.0J/cm2. The lesion depth demonstrated clear dose dependence. Lesions generated in ex vivo preparations of human trabecular meshwork in a fluid environment also demonstrated dose dependence, 50 pulses being sufficient to create a hole within the trabecular meshwork extending to Schlemm's canal. The dose dependence of the ablation depth combined with the ability of this technique to create a conduit through to Schlemm's canal demonstrates the potential of this technique for ophthalmological applications requiring precise and controlled intraocular tissue removal and has potential applications in the treatment and management of glaucoma.

  1. Gauge factors of fibre Bragg grating strain sensors in different types of optical fibres

    NASA Astrophysics Data System (ADS)

    Jülich, Florian; Aulbach, Laura; Wilfert, Andre; Kratzer, Peter; Kuttler, Rolf; Roths, Johannes

    2013-09-01

    Gauge factors of fibre Bragg grating (FBG)-based strain sensors that had been inscribed into three different types of optical fibres, which differ in core diameters and doping concentrations, were determined at room temperature with high accuracy. Repeated measurements were carried out with several samples of each type of fibre to allow statistical evaluations. For each type, the gauge factors were measured in two configurations: when the bare fibres were glued on a specimen at the location of the FBG and when they were vertically suspended and not bonded to any structure at the location of the FBG. By combining the results of both configurations, the strain transfer ratio of the gluing process and the strain-optic coefficient, peff, of the different types of fibres were determined. The strain-optic coefficient was found to vary up to 1.5% for the different types of optical fibres. The strain transfer ratio was obtained to be close to unity (>99%), showing the high quality of the gluing technique employed. The investigations demonstrate that highly accurate strain sensing is possible with fibre-optic strain sensors. The results are important for the development of accurate and reliable attaching techniques for coated sensor fibres and fibre-optic sensor patches.

  2. Rare-earth doped fibre optic devices and asymmetric fibre couplers

    NASA Astrophysics Data System (ADS)

    Sanaei, Farin

    The objective of the work reported in this thesis was to improve the quality and range of rare-earth doped fibre optic devices and asymmetric fibre couplers which can be fabricated for all-optical systems. This objective has been realised by improvements to the existing fibre fabrication processes and fused tapered coupler machine and by the generation of new fabrication techniques. An improved Flash-Condensation technique for the deposition of multi-layer highly-doped cladding fibre has been developed and tested. As a result a highly Yb-doped cladding fibre has been fabricated and characterised. It has been shown that up to 7wt% phosphorous pentoxide together with up to 1.4wt% lanthanide oxide can be doped into a multi-layer cladding fibre successfully. As far as it is known, no previous work on doping a thick cladding with Yb 3+ ions has been reported. We have shown experimentally that a 94% efficient superfluorescent fibre source in the 950-1150nm range using a highly doped cladding fibre can be designed and fabricated. This is the highest superfluorescent efficiency ever reported in the literature. By taking advantage of the superfluorescence of a large Yb-cladding doped fibre, we have demonstrated a singlemode fibre laser with a linewidth of 0.3nm and a slope efficiency of 79%. This means that by using a high pump power we can achieve many watts of laser power in the fibre very easily. Again, this is the highest slope efficiency ever reported. For the purpose of making application specific couplers, we have designed and improved the equipment control system for the fabrication of fused tapered fibre devices, and have developed various procedures for making better couplers. We have also successfully fabricated and analysed asymmetric fused fibre couplers, with the highest reported asymmetric coupling of 24:1. Using eight of these low loss asymmetric couplers, a prototype passive all-optical fibre data bus was constructed and analysed. Such data buses are very

  3. Low Cost Carbon Fibre for Automotive Applications Part 1: Low Cost Carbon Fibre Development

    SciTech Connect

    Warren, Charles David; Das, Sujit; Wheatley, Dr. Alan

    2014-01-01

    In pursuit of the goal to produce ultra-lightweight fuel efficient vehicles, there has been great excitement during the last few years about the potential for using carbon fibre reinforced composites in high volume applications. Currently, the greatest hurdle that inhibits wider implementation of carbon fibre composites in transportation is the high cost of carbon fibre when compared to other candidate materials. However, significant research is being conducted to develop lower cost, high volume technologies for producing carbon fibre. This chapter will highlight ongoing research in this area.

  4. Fibre communications: Time-reversed twin

    NASA Astrophysics Data System (ADS)

    Ip, Ezra; Kahn, Joseph M.

    2013-07-01

    Co-propagating a signal with its phase conjugate along an optical fibre link makes it possible to mitigate unwanted nonlinear distortions and improve the signal-to-noise ratio in long-haul optical communication systems.

  5. Recent progress in polymer optical fibre gratings

    NASA Astrophysics Data System (ADS)

    Zhang, C.; Carroll, K.; Webb, D. J.; Bennion, I.; Kalli, K.; Emiliyanov, G.; Bang, O.; Kjær, E.; Peng, G. D.

    2008-04-01

    We describe our recent progress in polymer fibre Bragg grating technology, including the writing of the first FBGs in TOPAS cyclic olefin copolymer, enhancements to photosensitivity brought about by dopants and studies on grating annealing.

  6. Optical Fibre Pressure Sensors in Medical Applications

    PubMed Central

    Poeggel, Sven; Tosi, Daniele; Duraibabu, DineshBabu; Leen, Gabriel; McGrath, Deirdre; Lewis, Elfed

    2015-01-01

    This article is focused on reviewing the current state-of-the-art of optical fibre pressure sensors for medical applications. Optical fibres have inherent advantages due to their small size, immunity to electromagnetic interferences and their suitability for remote monitoring and multiplexing. The small dimensions of optical fibre-based pressure sensors, together with being lightweight and flexible, mean that they are minimally invasive for many medical applications and, thus, particularly suited to in vivo measurement. This means that the sensor can be placed directly inside a patient, e.g., for urodynamic and cardiovascular assessment. This paper presents an overview of the recent developments in optical fibre-based pressure measurements with particular reference to these application areas. PMID:26184228

  7. Carcinogenicity studies after intraperitoneal injection of two types of stone wool fibres in rats.

    PubMed

    Kamstrup, O; Ellehauge, A; Collier, C G; Davis, J M G

    2002-03-01

    A summary is given of the pathology results after intraperitoneal (i.p.) injection in rats of insulation wool HT, representing the new biosoluble types. The pathology results are compared with a previously conducted i.p. study with traditional stone wool D6 (with similar chemical composition to MMVF21). The HT fibre is characterized by a relatively high content of aluminium and a relatively low content of silica compared to MMVF21. HT has a high in vitro dissolution rate at pH 4.5, a relatively low dissolution rate at pH 7.5 and is less biopersistent than the MMVF21 fibre. Female Wistar rats received a dose of 2 x 10(9) WHO HT fibres by i.p. injection. The fibres had been size-selected to be largely rat respirable. The negative control group was exposed to saline. Following exposure, the animals were maintained until survival in one group fell below 20%. At this time, all animals were killed. All animals were subjected to a necropsy examination; any gross abnormalities observed at necropsy were subjected to histopathological examination. In addition, histopathology was carried out on a predefined list of tissues. The incidences of lesions and survival in the control and fibre dosed animals were compared using appropriate statistical methods to determine whether the dosed animals showed adverse effects on survival or a positive carcinogenic response. The main protocol for the previously conducted study with D6 (MMVF21) was similar, but the animals were maintained as long as they survived, and the WHO fibre dose was lower. The results of the comparative study showed a marked difference in the i.p. pathogenicity of D6 (MMVF21) and HT in terms of their carcinogenic potential. D6 (MMVF21) caused a statistically significant increase of mesotheliomas in the peritoneal cavity compared to the negative control, but the HT fibre did not cause any mesotheliomas or any increase in other tumour types. PMID:12074022

  8. Fibre-optic sensors in health care

    NASA Astrophysics Data System (ADS)

    Grazia Mignani, Anna; Baldini, Francesco

    1997-05-01

    Biomedical fibre-optic sensors are attractive for the measurement of physical, chemical and biochemical parameters and for spectral measurements directly performed on the patient. An overview of fibre-optic sensors for in vivo monitoring is given, with particular attention paid to the advantages that these sensors are able to offer in different application fields such as cardiovascular and intensive care, angiology, gastroenterology, ophthalmology, oncology, neurology, dermatology and dentistry.

  9. Photonic crystal fibres in biomedical investigations

    SciTech Connect

    Skibina, Yu S; Tuchin, Valerii V; Beloglazov, V I; Shteinmaeer, G; Betge, I L; Wedell, R; Langhoff, N

    2011-04-30

    The state of the art in the field of design and study of photonic crystal fibres for biomedical applications is considered and some original results recently obtained by the authors are presented. Optical properties of the fibres that offer prospects of their wide application as biological sensors, 'labs-on-a-chip', and facilities of electromagnetic radiation control in a wide range of wavelengths aimed at designing novel biomedical instrumentation are considered (optical technologies in biophysics and medicine)

  10. Folded fibre bus interconnects with distributed amplification

    NASA Astrophysics Data System (ADS)

    Lorenzo, Raul Hernandez; Urquhart, Paul; Lopez-Amo, Manuel

    1998-06-01

    An optical fibre network for application as an interconnect within major nodes is investigated theoretically. The network is configured as a folded bus in which the spine consists of erbium doped fibre to overcome the power division at the couplers. It is argued that high received powers with a narrow dynamic range can be obtained simultaneously with bit rates in the order of 10 Gbit/s and bit error rates of 10 -12 or less.

  11. Fibre Bragg grating for flood embankment monitoring

    NASA Astrophysics Data System (ADS)

    Markowski, Konrad; Nevar, Stanislau; Dworzanski, Adam; Hackiewicz, Krzysztof; Jedrzejewski, Kazimierz

    2014-11-01

    In this article we present the preliminary studies for the flood embankment monitoring system based on the fibre Bragg gratings. The idea of the system is presented. The Bragg resonance shift is transformed to the change of the power detected by the standard InGaAs photodiode. The discrimination of the received power was executed by another fibre Bragg grating with different parameters. The project of the fully functional system is presented as well.

  12. Efficiency of nonstationary transformation of the spatial coherence of pulsed laser radiation in a multimode optical fibre upon self-phase modulation

    SciTech Connect

    Kitsak, M A; Kitsak, A I

    2007-08-31

    The model scheme of the nonlinear mechanism of transformation (decreasing) of the spatial coherence of a pulsed laser field in an extended multimode optical fibre upon nonstationary interaction with the fibre core is theoretically analysed. The case is considered when the spatial statistics of input radiation is caused by phase fluctuations. The analytic expression is obtained which relates the number of spatially coherent radiation modes with the spatially energy parameters on the initial radiation and fibre parameters. The efficiency of decorrelation of radiation upon excitation of the thermal and electrostriction nonlinearities in the fibre is estimated. Experimental studies are performed which revealed the basic properties of the transformation of the spatial coherence of a laser beam in a multimode fibre. The experimental results are compared with the predictions of the model of radiation transfer proposed in the paper. It is found that the spatial decorrelation of a light beam in a silica multimode fibre is mainly restricted by stimulated Raman scattering. (fiber and integrated optics)

  13. Reinforcing of Cement Composites by Estabragh Fibres

    NASA Astrophysics Data System (ADS)

    Merati, A. A.

    2014-04-01

    The influence of Estabragh fibres has been studied to improve the performance characteristics of the reinforced cement composites. The concrete shrinkage was evaluated by counting the number of cracks and measuring the width of cracks on the surface of concrete specimens. Although, the Estabragh fibres lose their strength in an alkali environment of cement composites, but, the ability of Estabragh fibres to bridge on the micro cracks in the concrete matrix causes to decrease the width of the cracks on the surface of the concrete samples in comparison with the plain concrete. However, considering the mechanical properties of specimens such as bending strength and impact resistance, the specimens with 0.25 % of Estabragh fibre performed better in all respects compared to the physical and mechanical properties of reinforced cement composite of concrete. Consequently, by adding 0.25 % of Estabragh fibres to the cement composite of concrete, a remarkable improvement in physical and mechanical properties of fibre-containing cement composite is achieved.

  14. Dewatering of fibre suspensions by pressure filtration

    NASA Astrophysics Data System (ADS)

    Hewitt, Duncan R.; Paterson, Daniel T.; Balmforth, Neil J.; Martinez, D. Mark

    2016-06-01

    A theoretical and experimental study of dewatering of fibre suspensions by uniaxial compression is presented. Solutions of a one-dimensional model are discussed and asymptotic limits of fast and slow compression are explored. Particular focus is given to relatively rapid compression and to the corresponding development of spatial variations in the solidity and velocity profiles of the suspension. The results of complementary laboratory experiments are presented for nylon or cellulose fibres suspended in viscous fluid. The constitutive relationships for each suspension were measured independently. Measurements of the load for different fixed compression speeds, together with some direct measurements of the velocity profiles using particle tracking velocimetry, are compared with model predictions. The comparison is reasonable for nylon, but poor for cellulose fibres. An extension to the model, which allows for a strain-rate-dependent component in the network stress, is proposed, and is found to give a dramatic improvement in the model predictions for cellulose fibre suspensions. The reason for this improvement is attributed to the microstructure of cellulose fibres, which, unlike nylon fibres, are themselves porous.

  15. Fibre positioning algorithms for the WEAVE spectrograph

    NASA Astrophysics Data System (ADS)

    Terrett, David L.; Lewis, Ian J.; Dalton, Gavin; Abrams, Don Carlos; Aguerri, J. Alfonso L.; Bonifacio, Piercarlo; Middleton, Kevin; Trager, Scott C.

    2014-07-01

    WEAVE is the next-generation wide-field optical spectroscopy facility for the William Herschel Telescope (WHT) in La Palma, Canary Islands, Spain. It is a multi-object "pick and place" fibre fed spectrograph with more than one thousand fibres, similar in concept to the Australian Astronomical Observatory's 2dF1 instrument with two observing plates, one of which is observing the sky while other is being reconfigured by a robotic fibre positioner. It will be capable of acquiring more than 10000 star or galaxy spectra a night. The WEAVE positioner concept uses two robots working in tandem in order to reconfigure a fully populated field within the expected 1 hour dwell-time for the instrument (a good match between the required exposure times and the limit of validity for a given configuration due to the effects of differential refraction). This presents additional constraints and complications for the software that determines the optimal path from one configuration to the next, particularly given the large number of fibre crossings implied by the 1000 fibre multiplex. This paper describes the algorithms and programming techniques used in the prototype implementations of the field configuration tool and the fibre positioner robot controller developed to support the detailed design of WEAVE.

  16. Conduction in regenerating dorsal root fibres.

    PubMed

    Feasby, T E; Bostock, H; Sears, T A

    1981-03-01

    Rat dorsal roots were crushed and recordings of compound action potentials and single fibre longitudinal currents were made 12-85 days later from the regenerating portions. Maximum conduction velocities rose from 1.3 m/s at day 10 to 25.7 m/s by day 41 and single fibre velocities varied from 1.2 m/s at 12 days postcrush to 23.8 m/s at 85 days. Many fibres appeared to conduct continuously in the early stages, although the resolution of the technique was insufficient to exclude saltatory conduction over short internodes. Two fibres showed internodes of about 200 microns at 9 and 13 days of regeneration, suggesting that "nodal" regions may be formed before significant myelination. At 27 days post-crush and later, internodes were 300-425 microns in length. Many regenerating fibres had branches, both retrograde and orthograde. Reduced conduction velocities in rostral portions of regenerating fibres suggested tapering. PMID:6260903

  17. Knowledge about dietary fibre: a fibre study framework.

    PubMed

    Guiné, Raquel P F; Ferreira, Manuela; Correia, Paula; Duarte, João; Leal, Marcela; Rumbak, Ivana; Barić, Irena C; Komes, Drazenka; Satalić, Zvonimir; Sarić, Marijana M; Tarcea, Monica; Fazakas, Zita; Jovanoska, Dijana; Vanevski, Dragoljub; Vittadini, Elena; Pellegrini, Nicoletta; Szűcs, Viktória; Harangozó, Júlia; El-Kenawy, Ayman; El-Shenawy, Omnia; Yalçın, Erkan; Kösemeci, Cem; Klava, Dace; Straumite, Evita

    2016-09-01

    The objective of this work was to study the degree of knowledge about dietary fibre (DF), as influenced by factors such as gender, level of education, living environment or country. For this, a descriptive cross-sectional study was undertaken on a non-probabilistic sample of 6010 participants from 10 countries in different continents (Europe, Africa and America). The results showed that the participants revealed on average a positive but still low global level of knowledge, which alerts for the need to take some actions to further inform the population about DF and its role as a component of a healthy diet. The results also indicated differences between genders, levels of education, living environments and countries. The highest level of knowledge was revealed by the participants from female gender, with higher education and living in urban areas. Concerning the country, the best informed were the participants from Romania, followed by those from Portugal and Turkey while the least informed were from Egypt. PMID:27263981

  18. Development of high-power holmium-doped fibre amplifiers

    NASA Astrophysics Data System (ADS)

    Hemming, Alexander; Simakov, Nikita; Davidson, Alan; Oermann, Michael; Corena, Len; Stepanov, Dmitrii; Carmody, Neil; Haub, John; Swain, Robert; Carter, Adrian

    2014-03-01

    Resonantly pumped holmium fibre lasers present a range of opportunities for the development of novel fibre laser and amplifier devices due to the availability of mature, efficient high power thulium fibre pump lasers. In this paper we describe the operation of a large mode area holmium-doped fibre amplifier. The master-oscillator is an all-fibre linearly polarised, core pumped single mode laser operating at 27 W at 2.11 μm. This laser was amplified in a large mode area fibre producing up to 265 W of output power. This system is the first demonstration of a resonantly pumped holmiumdoped fibre amplifier. It is also the highest power fibre amplifier that is capable of operating in an atmospheric transmission window <2.05 μm. This monolithic all-fibre system is able to address a wide range of remote sensing, scientific, medical and defence applications.

  19. Health benefits of cereal fibre: a review of clinical trials.

    PubMed

    Smith, Caren E; Tucker, Katherine L

    2011-06-01

    Cereal fibre and whole-grain intakes have been consistently associated in the epidemiological literature with reduced mortality and risk of chronic disease including obesity, CVD and type 2 diabetes. The present review focuses on intervention trials with three primary aims: (1) understanding the mechanisms through which fibre consumption improves health (for example, examination of intermediate endpoints reflecting improved lipid, glucose and energy metabolism); (2) close evaluation of qualitative factors which modify fibre's effectiveness including physiochemical properties (for example, solubility, fermentability and viscosity), fibre extract molecular weight, fibre particle size and botanical structure of the fibre source grain; and (3) identification of areas in which additional research is needed. The first two aims typify the goals of nutrition research, in that improved understanding of the specific factors which determine fibre's health benefits has critical implications for dietary recommendations as well as improving understanding of physiological mechanisms. The third aim acknowledges the substantial gap between recommended and actual fibre intakes in many developed countries including the USA and the UK. In recognition of this deficit in total fibre intake, food manufacturing processes increasingly utilise fibre extracts and concentrates as food additives. However, whether fibre extracts provide similar health benefits to the fibre supplied in the constituents of whole grain is largely unexplored. The relative benefits of fibre extracts compared with whole-grain fibre sources therefore represent a critical area in which additional research is needed. PMID:21320383

  20. Ge-doped optical fibres as thermoluminescence dosimeters for kilovoltage X-ray therapy irradiations

    NASA Astrophysics Data System (ADS)

    Issa, Fatma; Latip, Nur Atiqah Abd; Bradley, David A.; Nisbet, Andrew

    2011-10-01

    We investigate key dosimetric parameters for the thermoluminescence (TL) of Ge-doped silica optical fibres irradiated by X-rays generated at 90 and 300 kVp. The parameters include dose response, reproducibility and fading. Relative dose measurements were performed, obtaining central axis percentage depth dose (PDD) values, use being made of doped fibres irradiated in water and solid water phantoms. TL yields were compared with published data and ionisation chamber measurements. Linearity to dose was demonstrated over the investigated range (0.1-6 Gy), with reproducibility to within±2%. TL fading was found to be minimal, at <1.5% over a 12 h period. The RMI 457 solid water phantom correction factor was found to be 1.155±0.152 and 0.955±0.221 at 90 and 300 kVp, respectively. The maximum discrepancy between PDD values obtained using optical fibres and ionisation chamber measurements was 2.1% at 90 kVp, while the maximum discrepancy between tabulated data and measurements was 1.1% at 300 kVp.

  1. Growth of SiC nanowires using oil palm empty fruit bunch fibres infiltrated with tetraethyl orthosilicate

    NASA Astrophysics Data System (ADS)

    Chiew, Y. L.; Cheong, K. Y.

    2012-07-01

    SiC nanowires were produced by pyrolyzing oil palm empty fruit bunch fibres infiltrated with tetraethyl orthosilicate. The effects of the concentration of TEOS (10%, 50% and 100%) and the pyrolysis temperatures (1250 °C, 1300 °C, 1350 °C and 1400 °C) were studied. An increase in TEOS concentration led to an increment in silica content. However, when TEOS was infiltrated into the fibres, the small sizes of the lumens in the oil palm fibres and low fluidity of TEOS resulted in lower amount of silica deposited onto the surface when the concentration was increased to 100%. This in turn resulted in a lower yield of SiC nanowires at higher TEOS concentration. When pyrolysis temperature was raised, there was a decrease in diameter but the lengths of nanowires reached tens of μm. The growth of the nanowires was attributed to the combination of solid-state reaction and vapour-solid growth mechanisms.

  2. EDITORIAL: Optical Fibre Sensors 17 (OFS-17)

    NASA Astrophysics Data System (ADS)

    Tatam, Ralph P.; Jones, Julian D. C.

    2006-05-01

    This special issue of Measurement Science and Technology provides an overview of current developments in the field of optical fibre sensors. The papers presented here are more detailed versions of those presented at the 17th Optical Fibre Sensors conference (OFS-17) held at the Oud St-Jan Art and Congress Centre in Bruges, Belgium, from 23 27 May 2005. The first OFS conference was held in London in 1983 and the conference series is now held in international locations every 18 months and is the recognized venue for presentations of papers describing recent developments in the field of fibre optic sensing. The conference in Bruges was the largest to date of the OFS series with approximately 450 attendees and consisted of a plenary talk, describing photonic crystal gas sensors, ten invited contributions, 51 oral presentations and 197 posters. A third of the papers in this special issue are concerned with fibre Bragg and long period gratings, reflecting the widespread interest in this technology. Papers describe new laser based fabrication and processing techniques, signal processing methods, and applications to the measurement of physical parameters such as radiation detection, hydrogen sensing, load monitoring in wind turbines and stress measurement for geotechnical applications. Other non-grating sensing methodologies are presented for the measurement of gases, refractive index, colour and electric field/voltage. In addition to the descriptions of optical fibres sensors and signal processing schemes there are a number of contributions describing developments in enabling technologies such as sources for use with fibre sensors including, for example, quantum dots for temperature sensing. Developments in emerging technologies such as nanostructured fibres for sensing and investigating the sensing properties of carbon nanotubes using fibre sensor techniques are described along with the use of coherent imaging fibre bundles for flow measurement applications. We hope that

  3. Properties of Wood Fibre-Polypropylene Composites: Effect of Wood Fibre Source

    NASA Astrophysics Data System (ADS)

    Butylina, Svetlana; Martikka, Ossi; Kärki, Timo

    2011-04-01

    This study examined the effect of type of wood fibre source on the physical and mechanical properties of wood fibre-polypropylene composites. Wood flour, fibres of heat-treated wood and pellets were used as sources of wood fibres in the manufacturing process. All studied wood fibre-polypropylene composites were made from 75% wood, 22% recycled polypropylene (PP) and 3% maleated polypropylene (MAPP). Wood fibre-polypropylene composites were compounded in a conical twin-screw extruder. Water absorption and thickness swelling were studied. Mechanical properties of the composites were characterised by tensile, flexural, and impact testing. Micromechanical deformation processes were investigated using scanning electron microscopy done on the fractured surfaces of broken samples. The durability of composites exposed to three accelerated cycles of water immersion, freezing and thawing was examined. The results showed that the density of the composites was a key factor governing water absorption and thickness swelling. A significant improvement in tensile strength, flexural strength, and Charpy impact strength was observed for composites reinforced with heat-treated fibre compared to composites reinforced with pellets and especially to wood flour reinforced composites. The flexural strength and dimensional stability performance reduced after exposure to freeze-thaw cycling for all composites, but the degree of these changes was dependent on the wood fibre source.

  4. Magnesium Coated Bioresorbable Phosphate Glass Fibres: Investigation of the Interface between Fibre and Polyester Matrices

    PubMed Central

    Liu, Xiaoling; Grant, David M.; Parsons, Andrew J.; Harper, Lee T.; Rudd, Chris D.; Ahmed, Ifty

    2013-01-01

    Bioresorbable phosphate glass fibre reinforced polyester composites have been investigated as replacement for some traditional metallic orthopaedic implants, such as bone fracture fixation plates. However, composites tested revealed loss of the interfacial integrity after immersion within aqueous media which resulted in rapid loss of mechanical properties. Physical modification of fibres to change fibre surface morphology has been shown to be an effective method to improve fibre and matrix adhesion in composites. In this study, biodegradable magnesium which would gradually degrade to Mg2+ in the human body was deposited via magnetron sputtering onto bioresorbable phosphate glass fibres to obtain roughened fibre surfaces. Fibre surface morphology after coating was observed using scanning electron microscope (SEM). The roughness profile and crystalline texture of the coatings were determined via atomic force microscope (AFM) and X-ray diffraction (XRD) analysis, respectively. The roughness of the coatings was seen to increase from 40 ± 1 nm to 80 ± 1 nm. The mechanical properties (tensile strength and modulus) of fibre with coatings decreased with increased magnesium coating thickness. PMID:24066297

  5. Refractive Index Sensitivity of Tilted Long Period Fibre Gratings Written in Thinned Cladding Fibre

    NASA Astrophysics Data System (ADS)

    Zhao, Yunhe; Liu, Yunqi; Guo, Qiang; Wang, Tingyun

    2016-02-01

    We demonstrated the fabrication of tilted long period fibre gratings written in the thinned cladding fibre by CO2 laser. The refractive index characteristics of the gratings with different tilted angles were investigated experimentally. The experimental results show that the grating with larger tilted angle has higher sensitivity to the surrounding refractive index changes.

  6. Modeling vitreous silica bilayers

    NASA Astrophysics Data System (ADS)

    Kumar, Avishek; Wilson, Mark; Sherrington, David; Thorpe, Michael

    2014-03-01

    The recent synthesis and imaging of bilayers of vitreous silica has led to a wealth of new information. We have modeled the experimentally-observed bilayer using a computer assembly procedure to form a network of corner-sharing tetrahedra, which is then mirror-reflected to form a bilayer. We show that the vitreous silica bilayer has additional macroscopic degrees of freedom iff there is a symmetry plane through the center of the bilayer going through the central layer of oxygen ions that join the upper and lower monolayers. We have computer-refined the experimental coordinates to determine the density, and other structural characteristics such as the Si-Si pair distribution function, Si-O-Si bond angle distribution and the Aboav-Weaire law.

  7. Viscoelasticity of silica gels

    SciTech Connect

    Scherer, G.W.

    1995-12-01

    The response of silica gels to mechanical loads depends on the properties of the solid phase and the permeability of the network. Understanding this behavior is essential for modeling of stresses developed during drying or heating of gels. The permeability and the mechanical properties are readily determined from a simple beam-bending experiment, by measuring the load relaxation that occurs at constant deflection. Load decay results from movement of the liquid within the network; in addition, there may be viscoelastic relaxation of the network itself. Silica gel is viscoelastic in chemically aggressive media, but in inert liquids (such as ethanol or acetone) it is elastic. Experiments show that the viscoelastic relaxation time decreases as the concentration and pH of the water in the pore liquid increase. During drying, the permeability decreases and the viscosity increases, both exhibiting a power-law dependence on density of the gel network.

  8. Fibre-Bragg-grating writing in single-mode optical fibres by UV femtosecond pulses

    SciTech Connect

    Zagorul'ko, K A; Kryukov, P G; Dianov, Evgenii M; Dragomir, A; Nikogosyan, D N

    2003-08-31

    Fibre-Bragg-grating writing in single-mode optical fibres by the phase-mask method using 220-fs, 264-nm UV pulses of intensity 31 - 77 GW cm{sup -2} is reported for the first time. The achieved degree of modulation of the photoinduced refractive index was 1.9 x 10{sup -3} in an H{sub 2}-loaded SMF-28 telecommunication fibre and 1.1 x 10{sup -3} in a H{sub 2}-free Nufern GF1 fibre. The dependence of the induced refractive index on the intensity for the same irradiation fluences in the case of the H{sub 2}-loaded SMF-28 fibre shows that the refractive index is induced due to nonlinear absorption. (letters)

  9. Influence of fibre design and curvature on crosstalk in multi-core fibre

    NASA Astrophysics Data System (ADS)

    Egorova, O. N.; Astapovich, M. S.; Melnikov, L. A.; Salganskii, M. Yu; Mishkin, S. N.; Nishchev, K. N.; Semjonov, S. L.; Dianov, E. M.

    2016-03-01

    We have studied the influence of cross-sectional structure and bends on optical cross-talk in a multicore fibre. A reduced refractive index layer produced between the cores of such fibre with a small centre-to-centre spacing between neighbouring cores (27 μm) reduces optical cross-talk by 20 dB. The cross-talk level achieved, 30 dB per kilometre of the length of the multicore fibre, is acceptable for a number of applications where relatively small lengths of fibre are needed. Moreover, a significant decrease in optical cross-talk has been ensured by reducing the winding diameter of multicore fibres with identical cores.

  10. Fibre Body’: The Concept of Fibre in Eighteenth-century Medicine, c.1700–401

    PubMed Central

    Ishizuka, Hisao

    2012-01-01

    This paper attempts a comprehensive account of ‘fibre medicine’ elaborated by iatromechanists from c. 1700 to c. 1740. Fibre medicine, a medical theory informed by the notion of the fibre, has been neglected by medical historians despite the pivotal role played by the fibre in animal economy. Referring to a wide range of medical fields such as anatomy, physiology, pathology, therapeutics and life sciences, this paper elucidates the ways that the fibre serves as an indispensable concept for iatromechanists to establish their medical theories. This paper also highlights the metaphorical dimension of the fibre as an integral part of fibre medicine. In re-evaluating the concept of the fibre, this paper seeks to redress the neuro-centric view of eighteenth-century medicine, and attempts to locate the fibre body amidst the fundamental shift from humoralism to solidism. PMID:23112385

  11. Spun microstructured optical fibres for Faraday effect current sensors

    SciTech Connect

    Chamorovsky, Yury K; Starostin, Nikolay I; Morshnev, Sergey K; Gubin, Vladimir P; Ryabko, Maksim V; Sazonov, Aleksandr I; Vorob'ev, Igor' L

    2009-11-30

    We report a simple design of spun holey fibres and the first experimental study of the magneto-optical response of spun microstructured fibres with high built-in birefringence. Such fibres enable the Faraday-effect-induced phase shift to effectively accumulate in a magnetic field even at very small coiling diameters. For example, the magneto-optical sensitivity of a 5-mm-diameter fibre coil consisting of 100 turns is {approx}70% that of an ideal fibre, in good agreement with theoretical predictions. (optical fibres and fibreoptic sensors)

  12. A flax fibre proteome: identification of proteins enriched in bast fibres

    PubMed Central

    Hotte, Naomi SC; Deyholos, Michael K

    2008-01-01

    Background Bast fibres from the phloem tissues of flax are scientifically interesting and economically useful due in part to a dynamic system of secondary cell wall deposition. To better understand the molecular mechanisms underlying the process of cell wall development in flax, we extracted proteins from individually dissected phloem fibres (i.e. individual cells) at an early stage of secondary cell wall development, and compared these extracts to protein extracts from surrounding, non-fibre cells of the cortex, using fluorescent (DiGE) labels and 2D-gel electrophoresis, with identities assigned to some proteins by mass spectrometry. Results The abundance of many proteins in fibres was notably different from the surrounding non-fibre cells of the cortex, with approximately 13% of the 1,850 detectable spots being significantly (> 1.5 fold, p ≤ 0.05) enriched in fibres. Following mass spectrometry, we assigned identity to 114 spots, of which 51 were significantly enriched in fibres. We observed that a K+ channel subunit, annexins, porins, secretory pathway components, β-amylase, β-galactosidase and pectin and galactan biosynthetic enzymes were among the most highly enriched proteins detected in developing flax fibres, with many of these proteins showing electrophoretic patterns consistent with post-translational modifications. Conclusion The fibre-enriched proteins we identified are consistent with the dynamic process of secondary wall deposition previously suggested by histological and biochemical analyses, and particularly the importance of galactans and the secretory pathway in this process. The apparent abundance of β-amylase suggests that starch may be an unappreciated source of materials for cell wall biogenesis in flax bast fibres. Furthermore, our observations confirm previous reports that correlate accumulation proteins such as annexins, and specific heat shock proteins with secondary cell wall deposition. PMID:18447950

  13. 21 CFR 182.1711 - Silica aerogel.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Silica aerogel. 182.1711 Section 182.1711 Food and... GENERALLY RECOGNIZED AS SAFE Multiple Purpose GRAS Food Substances § 182.1711 Silica aerogel. (a) Product. Silica aerogel as a finely powdered microcellular silica foam having a minimum silica content of...

  14. 21 CFR 582.1711 - Silica aerogel.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Silica aerogel. 582.1711 Section 582.1711 Food and....1711 Silica aerogel. (a) Product. Silica aerogel as a finely powdered microcellular silica foam having a minimum silica content of 89.5 percent. (b) (c) Limitations, restrictions, or explanation....

  15. 21 CFR 582.1711 - Silica aerogel.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Silica aerogel. 582.1711 Section 582.1711 Food and....1711 Silica aerogel. (a) Product. Silica aerogel as a finely powdered microcellular silica foam having a minimum silica content of 89.5 percent. (b) (c) Limitations, restrictions, or explanation....

  16. 21 CFR 182.1711 - Silica aerogel.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Silica aerogel. 182.1711 Section 182.1711 Food and....1711 Silica aerogel. (a) Product. Silica aerogel as a finely powdered microcellular silica foam having a minimum silica content of 89.5 percent. (b) (c) Limitations, restrictions, or explanation....

  17. 21 CFR 582.1711 - Silica aerogel.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Silica aerogel. 582.1711 Section 582.1711 Food and....1711 Silica aerogel. (a) Product. Silica aerogel as a finely powdered microcellular silica foam having a minimum silica content of 89.5 percent. (b) (c) Limitations, restrictions, or explanation....

  18. 21 CFR 582.1711 - Silica aerogel.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Silica aerogel. 582.1711 Section 582.1711 Food and....1711 Silica aerogel. (a) Product. Silica aerogel as a finely powdered microcellular silica foam having a minimum silica content of 89.5 percent. (b) (c) Limitations, restrictions, or explanation....

  19. 21 CFR 182.1711 - Silica aerogel.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Silica aerogel. 182.1711 Section 182.1711 Food and....1711 Silica aerogel. (a) Product. Silica aerogel as a finely powdered microcellular silica foam having a minimum silica content of 89.5 percent. (b) (c) Limitations, restrictions, or explanation....

  20. 21 CFR 182.1711 - Silica aerogel.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Silica aerogel. 182.1711 Section 182.1711 Food and....1711 Silica aerogel. (a) Product. Silica aerogel as a finely powdered microcellular silica foam having a minimum silica content of 89.5 percent. (b) (c) Limitations, restrictions, or explanation....

  1. Nanoscale plasticity in silica glass

    SciTech Connect

    Glosli, J.N.; Boercker, D.B.; Tesar, A.; Belak, J.

    1993-10-01

    Mechanisms of nano-scale plasticity and damage initiation in silica glass is examined using molecular dynamics simulation. Computer experiments are carried out by indenting a sharp diamond-like tool, containing 4496 atoms, into a silica slab consisting of 12288 atoms. Both elastic and plastic deformation of silica is observed during nanoindentation simulation; this transition occurs at an indentation of 1.25 nm, and the calculated hardness (15GPa for 1.5 nm indentation) agrees with experiment.

  2. Complex geometrical optics of nonlinear inhomogeneous fibres

    NASA Astrophysics Data System (ADS)

    Berczynski, Pawel

    2011-03-01

    This paper analyses the Gaussian beam (GB) evolution in nonlinear fibres with special attention given to the influence of the initial curvature of the wavefront and to the fibres' permittivity profile. The analysis is performed in the framework of paraxial complex geometrical optics (PCGO). This method reduces the problem of GB evolution in nonlinear and inhomogeneous media to the solution of ordinary differential equations, which can be easily solved either analytically or numerically. It is shown that the PCGO approach radically simplifies modelling of nonlinear phenomena in fibres as compared with standard methods of nonlinear optics such as the variational method approach and the method of moments. It is shown that the PCGO method readily supplies the solution of the nonlinear Schrödinger equation (NLS) for a self-focusing fibre with a focusing permittivity profile and provides a number of new results. The discussion on the interplay between the nonlinear (self-focusing and self-defocusing) and linear (focusing and defocusing) components of the total permittivity demonstrates the new possibilities to limit the collapse phenomenon in nonlinear fibres of Kerr type taking into account the effect of initial beam divergence.

  3. On singular fibres in F-theory

    NASA Astrophysics Data System (ADS)

    Braun, Andreas P.; Watari, Taizan

    2013-07-01

    In this paper, we propose a connection between the field theory local model (Katz-Vafa field theory) and the type of singular fibre in flat crepant resolutions of elliptic Calabi-Yau fourfolds, a class of fourfolds considered by Esole and Yau. We review the analysis of degenerate fibres for models with gauge groups SU(5) and SO(10) in detail, and observe that the naively expected fibre type is realized if and only if the Higgs vev in the field theory local model is unramified. To test this idea, we implement a linear (unramified) Higgs vev for the " E 6" Yukawa point in a model with gauge group SU(5) and verify that this indeed leads to a fibre of Kodaira type IV*. Based on this observation, we argue i) that the singular fibre types appearing in the fourfolds studied by Esole-Yau are not puzzling at all, (so that this class of fourfolds does not have to be excluded from the candidate of input data of some yet-unknown formulation of F-theory) and ii) that such fourfold geometries also contain more information than just the eigenvalues of the Higgs field vev configuration in the field theory local models.

  4. Are Fibre Channel SANs a Commodity?

    NASA Technical Reports Server (NTRS)

    Becker, Jeff; Jacob, Matt; Biegel, Bryan A. (Technical Monitor)

    2000-01-01

    The goal of this work is to evaluate the feasibility of putting together a Fibre Channel Storage Area Network with heterogeneous hardware running both open-source and commercial operating systems. Adherence to the Fibre Channel Specification is supposed to guarantee interoperability in such an environment. We also want to evaluate how difficult it might be to put together a SAN using open-source components. While all the commercial vendors provide Fibre Channel support, this comes at a cost, e.g., not only O/S and drivers, but usually an expensive support contract. The open-source model could lower the cost of building and maintaining a SAN. Of course, for this to be the case, the open-source platforms would have to provide the functionality to construct a SAN. We are assembling a Fibre Channel SAN from heterogeneous hardware (i386, alpha, sparc) running *BSD, Linux, Tru64, NT and Solaris operating systems. We are running several tests to investigate the level of Fibre Channel support provided by each OS. Our current testbed is specified in the table below. Currently, it only contains open-source platforms. We plan to add a PC running OpenBSD, as well as the following commercial systems: Sun Ultra 1/Solaris, DEC AlphaServer 4000/Tru64 Unix, Pentium Pro PC/Windows NT.

  5. Dietary fibre: consensus and controversy.

    PubMed

    Bijlani, R L

    1985-01-01

    Technological advances have reduced and refined man's plant food intake and consequently brought about an unprecedented decline in his consumption of dietary fibre (DF). The emergence of certain diseases selectively in regions which have been affected the most by this dietary change has led to an enhanced awareness of the functions of DF. DF is a heterogeneous group of substances which resist digestion by the endogenous enzymes of the human gut, although they are fermented to a substantial extent by the bacterial flora of the large intestine. Chemically, DF essentially consists of nonstarch polysaccharides and lignin, and its major constituents are cellulose, hemicelluose, lignin and pectin. The physiological effects of DF are attributable largely to its physicochemical properties. DF primarily affects gastrointestinal (GI) function; its effects are observable at all stages from ingestion through defaecation. It restricts caloric intake, shows gastric and small intestinal transit, and affects the activity of digestive enzymes and release of GI hormones. Its overall impact is to reduce apparent digestibility of nutrients marginally but consistently. In the large intestine, DF accelerates transit, supports bacterial growth and serves to hold water. As a result, the faecal weight and water content increase, and the transit time generally becomes shorter. Secondary to its GI effects, DF attenuates postprandial glycaemia and has long term effects on glucose tolerance and lipoprotein metabolism. These effects have important implications in the aetiopathogenesis of constipation and its sequelae including diverticulosis, cholesterol gallstones, colorectal cancer, obesity, diabetes mellitus and atherosclerosis. DF has traditionally been used therapeutically for constipation; now its use in diabetes is also well established. Our appreciation of the role of DF in human nutrition has undergone a major change in the last two decades. From a redundant constituent of plant foods

  6. Astronomical optical frequency comb generation in nonlinear fibres and ring resonators: optimization studies

    NASA Astrophysics Data System (ADS)

    Chavez Boggio, J. M.; Fremberg, T.; Bodenmüller, D.; Wysmolek, M.; Sanyic, H.; Fernando, H.; Neumann, J.; Kracht, D.; Haynes, R.; Roth, M. M.

    2012-09-01

    We here discuss recent progress on astronomical optical frequency comb generation at innoFSPEC-Potsdam. Two different platforms (and approaches) are numerically and experimentally investigated targeting medium and low resolution spectrographs at astronomical facilities in which innoFSPEC is currently involved. In the first approach, a frequency comb is generated by propagating two lasers through three nonlinear stages - the first two stages serve for the generation of low-noise ultra-short pulses, while the final stage is a low-dispersion highly-nonlinear fibre where the pulses undergo strong spectral broadening. In our approach, the wavelength of one of the lasers can be tuned allowing the comb line spacing being continuously varied during the calibration procedure - this tuning capability is expected to improve the calibration accuracy since the CCD detector response can be fully scanned. The input power, the dispersion, the nonlinear coefficient, and fibre lengths in the nonlinear stages are defined and optimized by solving the Generalized Nonlinear Schrodinger Equation. Experimentally, we generate the 250GHz line-spacing frequency comb using two narrow linewidth lasers that are adiabatically compressed in a standard fibre first and then in a double-clad Er/Yb doped fibre. The spectral broadening finally takes place in a highly nonlinear fibre resulting in an astro-comb with 250 calibration lines (covering a bandwidth of 500 nm) with good spectral equalization. In the second approach, we aim to generate optical frequency combs in dispersion-optimized silicon nitride ring resonators. A technique for lowering and flattening the chromatic dispersion in silicon nitride waveguides with silica cladding is proposed and demonstrated. By minimizing the waveguide dispersion in the resonator two goals are targeted: enhancing the phase matching for non-linear interactions and producing equally spaced resonances. For this purpose, instead of one cladding layer our design

  7. Study of injection moulded long glass fibre-reinforced polypropylene and the effect on the fibre length and orientation distribution

    NASA Astrophysics Data System (ADS)

    Parveeen, B.; Caton-Rose, P.; Costa, F.; Jin, X.; Hine, P.

    2014-05-01

    Long glass fibre (LGF) composites are extensively used in manufacturing to produce components with enhanced mechanical properties. Long fibres with length 12 to 25mm are added to a thermoplastic matrix. However severe fibre breakage can occur in the injection moulding process resulting in shorter fibre length distribution (FLD). The majority of this breakage occurs due to the melt experiencing extreme shear stress during the preparation and injection stage. Care should be taken to ensure that the longer fibres make it through the injection moulding process without their length being significantly degraded. This study is based on commercial 12 mm long glass-fibre reinforced polypropylene (PP) and short glass fibre Nylon. Due to the semi-flexiable behaviour of long glass fibres, the fibre orientation distribution (FOD) will differ from the orientation distribution of short glass fibre in an injection molded part. In order to investigate the effect the change in fibre length has on the fibre orientation distribution or vice versa, FOD data was measured using the 2D section image analyser. The overall purpose of the research is to show how the orientation distribution chnages in an injection moulded centre gated disc and end gated plaque geometry and to compare this data against fibre orientation predictions obtained from Autodesk Moldflow Simulation Insight.

  8. Interstitial BiO molecule as a broadband IR luminescence centre in bismuth-doped silica glass

    SciTech Connect

    Sokolov, V O; Plotnichenko, V G; Dianov, Evgenii M

    2011-12-31

    Experimental data on absorption and luminescence in optical fibres with a Bi : SiO{sub 2} glass core are compared to experimentally determined and calculated spectroscopic properties of the BiO molecule. The results suggest that the IR luminescence of Bi : SiO{sub 2} glass is due to interstitial BiO molecules. This assumption is supported by quantum-chemical simulation results for a BiO molecule in a ring interstice of the silica glass network.

  9. Passively cooled 405 W ytterbium fibre laser utilising a novel metal coated active fibre

    NASA Astrophysics Data System (ADS)

    Daniel, Jae M. O.; Simakov, Nikita; Hemming, Alexander; Clarkson, W. Andrew; Haub, John

    2016-03-01

    We present a novel metal coated triple clad active fibre design, utilising an all glass inner cladding structure and aluminium outer coating. This metal coated active fibre enables a number of benefits to high power laser design, such as increase robustness and extended operating temperature range. As a demonstration of the advantages of this design a passively cooled ytterbium fibre laser is presented. A 20 m length of active fibre was coiled into a planar arrangement and mounted onto a high emissivity heatsink. Up to 405 W of output power was achieved without the need for active water or forced air cooling. The slope efficiency of this source was 74 % and maximum outer heat sink temperature was ~140°C. This arrangement allowed for significant weight and size savings to be achieved with the active fibre laser head weighing less than 100 g. We will discuss the design choices and trade-offs of metal coated active fibre on high power fibre laser systems as well as the prospects for further power scaling to the kW level.

  10. Biogeochemistry: Silica cycling over geologic time

    NASA Astrophysics Data System (ADS)

    Conley, Daniel J.; Carey, Joanna C.

    2015-06-01

    The Earth's long-term silica cycle is intimately linked to weathering rates and biogenic uptake. Changes in weathering rates and the retention of silica on land have altered silica availability in the oceans for hundreds of millions of years.

  11. Theoretical aspects of fibre laser cutting

    NASA Astrophysics Data System (ADS)

    Mahrle, A.; Beyer, E.

    2009-09-01

    Fibre lasers offer distinct advantages over established laser systems with respect to power efficiency, beam guidance and beam quality. Consequently, the potential of these new laser beam sources will be increasingly exploited for laser cutting applications that are conventionally carried out with CO2 lasers. However, theoretical estimates of the effective absorptivity at the cut front suggest that the shorter wavelength of the fibre laser in combination with its high focusability seems to be primarily advantageous for thin sheet metal cutting whereas the CO2 laser is probably still capable of cutting thicker materials more efficiently. This surprising result is a consequence of the absorptivity behaviour of metals that shows essential quantitative differences for the corresponding wavelengths of both laser sources as a function of the angle of incidence between the laser beam and the material to be cut. In evaluation of the revealed dependences, solution strategies for an improvement of the efficiency of fibre laser cutting of thicker metal sheets are suggested.

  12. On the topology of chromatin fibres

    PubMed Central

    Barbi, Maria; Mozziconacci, Julien; Victor, Jean-Marc; Wong, Hua; Lavelle, Christophe

    2012-01-01

    The ability of cells to pack, use and duplicate DNA remains one of the most fascinating questions in biology. To understand DNA organization and dynamics, it is important to consider the physical and topological constraints acting on it. In the eukaryotic cell nucleus, DNA is organized by proteins acting as spools on which DNA can be wrapped. These proteins can subsequently interact and form a structure called the chromatin fibre. Using a simple geometric model, we propose a general method for computing topological properties (twist, writhe and linking number) of the DNA embedded in those fibres. The relevance of the method is reviewed through the analysis of magnetic tweezers single molecule experiments that revealed unexpected properties of the chromatin fibre. Possible biological implications of these results are discussed. PMID:24098838

  13. Multimode fibres for micro-endoscopy

    NASA Astrophysics Data System (ADS)

    Turtaev, Sergey; Leite, Ivo T.; Čižmár, Tomáš

    2015-12-01

    There has been a tremendous effort in modern microscopy towards miniaturisation and fibre-based technology, driven by the need to access hostile or difficult environments in situ and in vivo. Most of these rely on reducing the size of endoscopes based on fibre-optic bundles, and systems incorporating microfabricated lenses. Recently, the use of standard multimode optical fibres for lensless microscopy has become possible mainly due to advances in holographic beam shaping. This article reviews the methods and techniques behind this progress paving theway towards minimally invasive in vivo imaging as well as other applications of multimode waveguides including on-chip integration of optical micro-manipulation and numerous other biophotonics techniques.

  14. Luminescent Properties of Cerium Doped Potassium Iodide Single Crystals in Response to γ-irradiation.

    PubMed

    Bangaru, S; Saradha, K; Muralidharan, G

    2015-05-01

    Potassium iodide doped with cerium ions were prepared by Bridgemann Stockbarger technique and investigated by optical absorption, Photoluminescence(PL), Thermoluminescence(TL), Photostimulated Luminescence(PSL) and TL emission. The optical absorption measurement indicates that F and V centers are formed in the crystals during the γ-ray irradiation process. Optical absorption and Photoluminescence studies confirm the presence of cerium ions in the trivalent state. Spectral distribution under the Thermoluminescence Emission(TLE) and Optically Stimulated Luminescence(OSL) support the idea that the defect annihilation process to be due to thermal release of F-electron in KI:Ce(3+) crystals. Both Ce(3+) and Ce(2+) emissions were observed in the Thermoluminescence emission of the crystals. Thermoluminescence(TL) has been identified to be due to thermal release of electron produced during colouration process. PMID:25744528

  15. Gold-supported cerium-doped NiOx catalysts for water oxidation

    NASA Astrophysics Data System (ADS)

    Ng, Jia Wei Desmond; García-Melchor, Max; Bajdich, Michal; Chakthranont, Pongkarn; Kirk, Charlotte; Vojvodic, Aleksandra; Jaramillo, Thomas F.

    2016-05-01

    The development of high-performance catalysts for the oxygen-evolution reaction (OER) is paramount for cost-effective conversion of renewable electricity to fuels and chemicals. Here we report the significant enhancement of the OER activity of electrodeposited NiOx films resulting from the combined effects of using cerium as a dopant and gold as a metal support. This NiCeOx–Au catalyst delivers high OER activity in alkaline media, and is among the most active OER electrocatalysts yet reported. On the basis of experimental observations and theoretical modelling, we ascribe the activity to a combination of electronic, geometric and support effects, where highly active under-coordinated sites at the oxide support interface are modified by the local chemical binding environment and by doping the host Ni oxide with Ce. The NiCeOx–Au catalyst is further demonstrated in a device context by pairing it with a nickel–molybdenum hydrogen evolution catalyst in a water electrolyser, which delivers 50 mA consistently at 1.5 V over 24 h of continuous operation.

  16. Synthesis, electrical and dielectric characterization of cerium doped nano copper ferrites

    SciTech Connect

    Malana, Muhammad Aslam Qureshi, Raheela Beenish; Ashiq, Muhammad Naeem; Zafar, Zafar Iqbal

    2013-11-15

    Graphical abstract: Lattice constant (a) and activation energy (Ea) as a function of Ce (cerium) content. - Highlights: • The simple and economic method has been adopted for the synthesis of nanoferrites. • The electrical resistivity increases with cerium concentration. • DC electrical resistivity of these materials favours their use in microwave devices. • Dielectric measurements show semiconductor nature of the synthesized ferrites. - Abstract: The nanosized CuFe{sub 2−x}Ce{sub x}O{sub 4} (x = 0.0, 0.2, 0.4, 0.6, 0.8) ferrites doped with cerium are synthesized by chemical co-precipitation method. The synthesized materials are characterized by XRD, FTIR, TGA and SEM. XRD analysis of cerium substituted copper ferrites confirms the cubic spinel structure. The average crystallite size calculated by using Scherrer's formula ranges from 37 to 53 nm. The values of cell constant and cell volume vary with the dopant concentration. These variations can be explained in terms of their ionic radii. The DC electrical resistivity, measured by two point probe method, increases with increase in dopant concentration while it decreases with rise in temperature exhibiting semiconductor behaviour. Energy of activation of these ferrites is calculated by using Arrhenius type resistivity plots. Dielectric measurements of the synthesized compounds show exponential decrease in dielectric constant and dielectric loss factor with increase in frequency. This indicates the normal dielectric behaviour of ferrites.

  17. Novel cerium doped glass-reinforced hydroxyapatite with antibacterial and osteoconductive properties for bone tissue regeneration.

    PubMed

    Morais, D S; Fernandes, S; Gomes, P S; Fernandes, M H; Sampaio, P; Ferraz, M P; Santos, J D; Lopes, M A; Sooraj Hussain, N

    2015-09-01

    The aim of this work was to develop a bioactive bone substitute with an effective antibacterial ability based on a cerium (Ce) doped glass-reinforced hydroxyapatite (GR-HA) composite. Developed composites were physicochemically characterized, using x-ray diffraction (XRD) analysis, SEM, energy dispersive x-ray spectroscopy (EDS), and flexural bending strength (FBS) tests. X-ray photoelectron spectroscopy (XPS) analysis was performed to analyze the oxidation state of Ce in the prepared doped glass. The antimicrobial activity of the composites was evaluated against Staphylococcus aureus, Staphylococcus epidermidis and Pseudomonas aeruginosa; whether the cytocompatibility profile was assayed with human osteoblastic-like cells (Mg-63 cell line). The results revealed that the Ce inclusion in the GR-HA matrix induced the antimicrobial ability of the composite. In addition, Ce-doped materials reported an adequate biological behavior following seeding of osteoblastic populations, by inducing cell adhesion and proliferation. Developed materials were also found to enhance the expression of osteoblastic-related genes. Overall, the developed GR-HA_Ce composite is a prospective candidate to be used within the clinical scenario with a successful performance due to the effective antibacterial properties and capability of enhancing the osteoblastic cell response. PMID:26391473

  18. Cerium doped red mud catalytic ozonation for bezafibrate degradation in wastewater: Efficiency, intermediates, and toxicity.

    PubMed

    Xu, Bingbing; Qi, Fei; Sun, Dezhi; Chen, Zhonglin; Robert, Didier

    2016-03-01

    In this study, the performance of bezafibrate (BZF) degradation and detoxification in the aqueous phase using cerium-modified red mud (RM) catalysts prepared using different cerium sources and synthesis methods were evaluated. Experimental results showed that the surface cerium modification was responsible for the development of the catalytic activity of RM and this was influenced by the cerium source and the synthesis method. Catalyst prepared from cerium (IV) by precipitation was found to show the best catalytic activity in BZF degradation and detoxification. Reactive oxygen species including peroxides, hydroxyl radicals, and super oxide ions were identified in all reactions and we proposed the corresponding catalytic reaction mechanism for each catalyst that prepared from different cerium source and method. This was supported by the intermediates profiles that were generated upon BZF degradation. The surface and the structural properties of cerium-modified RM were characterized in detail by several analytical methods. Two interesting findings were made: (1) the surface texture (specific surface area and mesoporous volume) influenced the catalytic reaction pathway; and (2) Ce(III) species and oxygen vacancies were generated on the surface of the catalyst after cerium modification. This plays an important role in the development of the catalytic activity. PMID:26706928

  19. Radiation damage studies of cerium-doped radiation-resistant lead glass detectors

    NASA Astrophysics Data System (ADS)

    Adams, M. R.; Engelmann, R.; Grannis, P. D.; Horstkotte, J.; Godfrey, L.; Linn, S. L.; Marx, M. D.; Timms, J.; Tuts, P. M.; Willins, J.; Ahrens, L.; Aronson, S.; Levy, P. W.; Yamin, P.; Franzini, P.; Youssef, S.; Cutts, D.; Callas, J.

    1985-08-01

    Optical absorption measurements have been made on unirradiated and irradiated samples of cerium oxide doped lead silicate particle detector glasses. The addition of CeO 2 introduces one prominent and one weak absorption band near the ultraviolet transmission limit. However the CeO 2 greatly reduces the rate of formation of the radiation induced absorption. Detector size blocks of lead glass with 0.0, 0.25, and 1.2 weight percent CeO 2 were used to determine the energy resolution for 5 GeV electrons. The resolution deteriorates from 12 to 33% as the CeO 2 changes from 0.0 to 1.2%. At these CeO 2 levels, calculations indicate the yield of doped glass becomes superior to that of undoped glass for doses greater than 500 rad.

  20. Grain Growth Behavior, Tensile Impact Ductility, and Weldability of Cerium-Doped Iridium Alloys

    SciTech Connect

    McKamey, C.G.

    2002-05-28

    An iridium alloy doped with small amounts of cerium and thorium is being developed as a potential replacement for the iridium-based DOP-26 alloy (doped with thorium only) that is currently used by the National Aeronautics and Space Administration (NASA) for cladding and post-impact containment of the radioactive fuel in radioisotope thermoelectric generator (RTG) heat sources which provide electric power for interplanetary spacecraft. This report summarizes results of studies conducted to date under the Iridium Alloy Characterization and Development subtask of the Radioisotope Power System Materials Production and Technology Program to characterize the properties of the iridium-based alloy (designated as DOP-40) containing both cerium and thorium. Included within this report are data on grain growth of sheet material in vacuum and low-pressure oxygen environments, grain growth in vacuum of the clad vent set cup material, weldability, and the effect of grain size and test temperature on tensile properties. Where applicable, data for the DOP-26 alloy are included for comparison. Both grain size and grain-boundary cohesion affect the ductility of iridium alloys. In this study it was found that cerium and thorium, when added together, refine grain size more effectively than when thorium is added by itself (especially at high temperatures). In addition, the effect of cerium additions on grain-boundary cohesion is similar to that of thorium. Mechanical testing at both low ({approx} 10{sup -3}s{sup -1}) and high ({approx} 10{sup -3}s{sup -1}) strain rates showed that the Ce/Th-doped alloys have tensile ductilities that are as good or better than the DOP-26 alloy. The general conclusion from these studies is that cerium can be used to replace some of the radioactive thorium currently used in DOP-26 while maintaining or improving its metallurgical properties. The current DOP-26 alloy meets all requirements for cladding the radioactive fuel in the RTG heat source, but the new DOP-40 alloy could serve as a back-up alloy to be used if the costs of refining, handling, and transporting DOP-26 become prohibitively high.

  1. Evaluating displacement damage in cerium-doped yttrium borate using photoluminescence lifetime

    NASA Astrophysics Data System (ADS)

    Gollub, S. L.; Mitchell, C. A.; Rogers, B. R.; Walker, D. G.

    2015-07-01

    The photoluminescence lifetime and spectrum of YBO3:Ce3+ are observed before and after proton bombardment. The optical properties change under irradiation, and thus the material can record information about the radiation exposure. As the fluence of 1 MeV protons increases beyond 1014proton/cm2, the lifetime of YBO3:Ce3+ decreases nearly exponentially. Furthermore, by changing the concentration of cerium, the sensitivity of the material to the radiation induced defects is controllable such that lower-doped YBO3:Ce3+ is more sensitive to damage.

  2. Structural and optical studies of cerium doped lead tungstate nano phosphor

    NASA Astrophysics Data System (ADS)

    Tawde, Dharmendra V.

    The rapidly expanding oil sands of western Canada, the third largest reserves in the world, are creating serious challenges, such as ecological harm, labour shortages, and extensive natural gas consumption. This thesis develops three practical real options models to evaluate the feasibility of oil sands projects and to estimate the optimal rate of oil sands expansion, while accounting for the stated concerns. (Abstract shortened by UMI.).

  3. Measurement of dispersion in optical fibres with a microstructure cladding

    SciTech Connect

    Levchenko, A E; Kurkov, Andrei S; Semenov, S L

    2005-09-30

    Based on the interferometric technique, a setup is built for measuring the spectral dependence of chromatic dispersion in fibres with a microstructure cladding. The setup provides measurements in a broad spectral range from 670 to 1550 nm taking birefringence in the fibre into account. The results of measurements of dispersion in a standard fibre with this setup and a commercial device are in good agreement. (optical fibres)

  4. Presynaptic Calcium Signalling in Cerebellar Mossy Fibres

    PubMed Central

    Thomsen, Louiza B.; Jörntell, Henrik; Midtgaard, Jens

    2009-01-01

    Whole-cell recordings were obtained from mossy fibre terminals in adult turtles in order to characterize the basic membrane properties. Calcium imaging of presynaptic calcium signals was carried out in order to analyse calcium dynamics and presynaptic GABA B inhibition. A tetrodotoxin (TTX)-sensitive fast Na+ spike faithfully followed repetitive depolarizing pulses with little change in spike duration or amplitude, while a strong outward rectification dominated responses to long-lasting depolarizations. High-threshold calcium spikes were uncovered following addition of potassium channel blockers. Calcium imaging using Calcium-Green dextran revealed a stimulus-evoked all-or-none TTX-sensitive calcium signal in simple and complex rosettes. All compartments of a complex rosette were activated during electrical activation of the mossy fibre, while individual simple and complex rosettes along an axon appeared to be isolated from one another in terms of calcium signalling. CGP55845 application showed that GABA B receptors mediated presynaptic inhibition of the calcium signal over the entire firing frequency range of mossy fibres. A paired-pulse depression of the calcium signal lasting more than 1 s affected burst firing in mossy fibres; this paired-pulse depression was reduced by GABA B antagonists. While our results indicated that a presynaptic rosette electrophysiologically functioned as a unit, topical GABA application showed that calcium signals in the branches of complex rosettes could be modulated locally, suggesting that cerebellar glomeruli may be dynamically sub-compartmentalized due to ongoing inhibition mediated by Golgi cells. This could provide a fine-grained control of mossy fibre-granule cell information transfer and synaptic plasticity within a mossy fibre rosette. PMID:20162034

  5. Trace elements in hazardous mineral fibres.

    PubMed

    Bloise, Andrea; Barca, Donatella; Gualtieri, Alessandro Francesco; Pollastri, Simone; Belluso, Elena

    2016-09-01

    Both occupational and environmental exposure to asbestos-mineral fibres can be associated with lung diseases. The pathogenic effects are related to the dimension, biopersistence and chemical composition of the fibres. In addition to the major mineral elements, mineral fibres contain trace elements and their content may play a role in fibre toxicity. To shed light on the role of trace elements in asbestos carcinogenesis, knowledge on their concentration in asbestos-mineral fibres is mandatory. It is possible that trace elements play a synergetic factor in the pathogenesis of diseases caused by the inhalation of mineral fibres. In this paper, the concentration levels of trace elements from three chrysotile samples, four amphibole asbestos samples (UICC amosite, UICC anthophyllite, UICC crocidolite and tremolite) and fibrous erionite from Jersey, Nevada (USA) were determined using inductively coupled plasma mass spectrometry (ICP-MS). For all samples, the following trace elements were measured: Li, Be, Sc, V, Cr, Mn, Co, Ni, Cu, Zn, As, Rb, Sr, Y, Sb, Cs, Ba, La, Pb, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Th, U. Their distribution in the various mineral species is thoroughly discussed. The obtained results indicate that the amount of trace metals such as Mn, Cr, Co, Ni, Cu and Zn is higher in anthophyllite and chrysotile samples, whereas the amount of rare earth elements (REE) is higher in erionite and tremolite samples. The results of this work can be useful to the pathologists and biochemists who use asbestos minerals and fibrous erionite in-vitro studies as positive cyto- and geno-toxic standard references. PMID:27289526

  6. OPTICAL FIBRES AND FIBREOPTIC SENSORS: Fibreoptic distributed temperature sensor with spectral filtration by directional fibre couplers

    NASA Astrophysics Data System (ADS)

    Kuznetsov, A. G.; Babin, Sergei A.; Shelemba, Ivan S.

    2009-11-01

    We demonstrate a Raman-based all-fibre temperature sensor utilising a pulsed erbium fibre laser. The sensor is made of a standard single-mode telecom fibre, SMF-28, and includes a number of directional couplers as band-pass filters. The temperature profile along a 7-km fibreoptic line is measured with an accuracy of 2oC and a spatial resolution of 10 m. In data processing, we take into account the difference in attenuation between the spectral components of the backscatter signal.

  7. ZBLAN, Silica Fiber Comparison

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This graph depicts the increased signal quality possible with optical fibers made from ZBLAN, a family of heavy-metal fluoride glasses (fluorine combined zirconium, barium, lanthanum, aluminum, and sodium) as compared to silica fibers. NASA is conducting research on pulling ZBLAN fibers in the low-g environment of space to prevent crystallization that limits ZBLAN's usefulness in optical fiber-based communications. In the graph, a line closer to the black theoretical maximum line is better. Photo credit: NASA/Marshall Space Flight Center

  8. Fibre optic distributed differential displacement sensor

    NASA Astrophysics Data System (ADS)

    Wylie, Michael T. V.; Brown, Anthony W.; Colpitts, Bruce G.

    2011-05-01

    A Fibre Optic Distributed Differential Displacement Sensor is modelled and experimentally verified to determine shape. Created using a steel tape, 9/125 μm single mode fibre, and adhesive, the FODDDS can be used to determine shape or displacement of any object to which it is bonded. A circular shape is examined, and a radius of curvature comparison yields an error of 2%. The sensitivity of the FODDDS, for the substrate thickness used in this experiment, is shown to be 1.27 mm between adjacent data points, which corresponds to a radius of curvature of 103 m.

  9. Health benefits of cereal fibre: a review of clinical trials

    PubMed Central

    Smith, Caren E.; Tucker, Katherine L.

    2011-01-01

    Cereal fibre and whole-grain intakes have been consistently associated in the epidemiological literature with reduced mortality and risk of chronic disease including obesity, CVD and type 2 diabetes. The present review focuses on intervention trials with three primary aims: (1) understanding the mechanisms through which fibre consumption improves health (for example, examination of intermediate endpoints reflecting improved lipid, glucose and energy metabolism); (2) close evaluation of qualitative factors which modify fibre’s effectiveness including physiochemical properties (for example, solubility, fermentability and viscosity), fibre extract molecular weight, fibre particle size and botanical structure of the fibre source grain; and (3) identification of areas in which additional research is needed. The first two aims typify the goals of nutrition research, in that improved understanding of the specific factors which determine fibre’s health benefits has critical implications for dietary recommendations as well as improving understanding of physiological mechanisms. The third aim acknowledges the substantial gap between recommended and actual fibre intakes in many developed countries including the USA and the UK. In recognition of this deficit in total fibre intake, food manufacturing processes increasingly utilise fibre extracts and concentrates as food additives. However, whether fibre extracts provide similar health benefits to the fibre supplied in the constituents of whole grain is largely unexplored. The relative benefits of fibre extracts compared with whole-grain fibre sources therefore represent a critical area in which additional research is needed. PMID:21320383

  10. Silica Fillers for elastomer Reinforement

    SciTech Connect

    Kohls, D.J.; Schaefer, D.W.

    2012-09-10

    This article summarizes recent work on the structure of precipitated silica used in the reinforcement of elastomers. Silica has a unique morphology, consisting of multiple structural levels that can be controlled through processing. The ability to control and characterize the multiple structures of precipitated silica is an example of morphological engineering for reinforcement applications. In this summary of some recent research efforts using precipitated silica, small-angle scattering techniques are described and their usefulness for determining the morphology of silica in terms of primary particles, aggregates, and agglomerates are discussed. The structure of several different precipitated silica powders is shown as well as the mechanical properties of elastomers reinforced with these silica particles. The study of the mechanical properties of filled elastomer systems is a challenging and exciting topic for both fundamental science and industrial application. It is known that the addition of hard particulates to a soft elastomer matrix results in properties that do not follow a straightforward rule of mixtures. Research efforts in this area have shown that the properties of filled elastomers are influenced by the nature of both the filler and the matrix, as well as the interactions between them. Several articles have reviewed the influence of fillers like silica and carbon black on the reinforcement of elastomers. In general, the structure-property relationships developed for filled elastomers have evolved into the following major areas: Filler structure, hydrodynamic reinforcement, and interactions between fillers and elastomers.

  11. Silica Fillers for elastomer Reinforement

    SciTech Connect

    Kohls, D.J.; Schaefer, D.W.

    2009-08-26

    This article summarizes recent work on the structure of precipitated silica used in the reinforcement of elastomers. Silica has a unique morphology, consisting of multiple structural levels that can be controlled through processing. The ability to control and characterize the multiple structures of precipitated silica is an example of morphological engineering for reinforcement applications. In this summary of some recent research efforts using precipitated silica, small-angle scattering techniques are described and their usefulness for determining the morphology of silica in terms of primary particles, aggregates, and agglomerates are discussed. The structure of several different precipitated silica powders is shown as well as the mechanical properties of elastomers reinforced with these silica particles. The study of the mechanical properties of filled elastomer systems is a challenging and exciting topic for both fundamental science and industrial application. It is known that the addition of hard particulates to a soft elastomer matrix results in properties that do not follow a straightforward rule of mixtures. Research efforts in this area have shown that the properties of filled elastomers are influenced by the nature of both the filler and the matrix, as well as the interactions between them. Several articles have reviewed the influence of fillers like silica and carbon black on the reinforcement of elastomers. In general, the structure-property relationships developed for filled elastomers have evolved into the following major areas: Filler structure, hydrodynamic reinforcement, and interactions between fillers and elastomers.

  12. Wood Fibre Reinforced Polypropylene Composites: Effect of Fibre Geometry and Coupling Agent on Physico-Mechanical Properties

    NASA Astrophysics Data System (ADS)

    Bledzki, Andrzej K.; Faruk, Omar

    2003-11-01

    Wood fibre reinforced polypropylene composites at fibre content 50% by weight have been prepared and different types of wood fibres (hard wood fibre, soft wood fibre, long wood fibre and wood chips) were treated with coupling agent (MAH-PP) to increase the interfacial adhesion with the matrix to improve the dispersion of the particles and to decrease the water sorption properties of the final composite. The present study investigated the tensile, flexural, charpy impact and impact properties of wood fibre reinforced polypropylene composites as a function of coupling agent and fibre length and structure. From the results it is observed that wood chips-PP composites showed better tensile and flexural properties comparative with the other wood fibre-PP composites with the addition of 5%MAH-PP, which is around 65% and 50% for tensile strength and flexural strength respectively. Hard wood fibre-PP composites showed better impact characteristic values comparative to other wood fibre-PP composites with the addition of 5%MAH-PP and damping index decreased about to 60%. Charpy impact strength also increased up to 60% with the addition of 5%MAH-PP for long wood fibre-PP composites. Water absorption and scanning electron microscopy of the composites are also investigated.

  13. Silaffins in Silica Biomineralization and Biomimetic Silica Precipitation

    PubMed Central

    Lechner, Carolin C.; Becker, Christian F. W.

    2015-01-01

    Biomineralization processes leading to complex solid structures of inorganic material in biological systems are constantly gaining attention in biotechnology and biomedical research. An outstanding example for biomineral morphogenesis is the formation of highly elaborate, nano-patterned silica shells by diatoms. Among the organic macromolecules that have been closely linked to the tightly controlled precipitation of silica in diatoms, silaffins play an extraordinary role. These peptides typically occur as complex posttranslationally modified variants and are directly involved in the silica deposition process in diatoms. However, even in vitro silaffin-based peptides alone, with and without posttranslational modifications, can efficiently mediate biomimetic silica precipitation leading to silica material with different properties as well as with encapsulated cargo molecules of a large size range. In this review, the biomineralization process of silica in diatoms is summarized with a specific focus on silaffins and their in vitro silica precipitation properties. Applications in the area of bio- and nanotechnology as well as in diagnostics and therapy are discussed. PMID:26295401

  14. Silaffins in Silica Biomineralization and Biomimetic Silica Precipitation.

    PubMed

    Lechner, Carolin C; Becker, Christian F W

    2015-08-01

    Biomineralization processes leading to complex solid structures of inorganic material in biological systems are constantly gaining attention in biotechnology and biomedical research. An outstanding example for biomineral morphogenesis is the formation of highly elaborate, nano-patterned silica shells by diatoms. Among the organic macromolecules that have been closely linked to the tightly controlled precipitation of silica in diatoms, silaffins play an extraordinary role. These peptides typically occur as complex posttranslationally modified variants and are directly involved in the silica deposition process in diatoms. However, even in vitro silaffin-based peptides alone, with and without posttranslational modifications, can efficiently mediate biomimetic silica precipitation leading to silica material with different properties as well as with encapsulated cargo molecules of a large size range. In this review, the biomineralization process of silica in diatoms is summarized with a specific focus on silaffins and their in vitro silica precipitation properties. Applications in the area of bio- and nanotechnology as well as in diagnostics and therapy are discussed. PMID:26295401

  15. Comparative study of WLS fibres for the ATLAS Tile Calorimeter

    NASA Astrophysics Data System (ADS)

    Gomes, A.; David, M.; Henriques, A.; Maio, A.

    1998-02-01

    The Wave Length Shifting (WLS) fibres are one of the most important components of the ATLAS barrel hadronic tile calorimeter (Tilecal). The fibres collect the hght produced in the injection molded scintillating tiles and transport it to the photomultipliers. Parameters like attenuation length and light yield are important, as well as flexibility and radiation hardness. Comparative results of WLS fibres produced by Bicron, Kuraray and Pol.Hi.Tech are presented. The performance of the fibres BCF91A from Bicron and S048 from Pol.Hi.Tech was significatively improved, but the most performant are still the double clad Y11 fibres from Kuraray.

  16. Comparative study of WLS fibres for the ATLAS tile calorimeter

    NASA Astrophysics Data System (ADS)

    Gomes, A.; David, M.; Henriques, A.; Maio, A.

    1997-02-01

    The Wave Length Shifting (WLS) fibres are one of the most important components of the ATLAS barrel hadronic tile calorimeter (Tilecal). The fibres collect the light produced in the injection molded scintillating tiles and transport it to the photomultipliers. Parameters like attenuation length and light yield are important, as well as flexibility and radiation hardness. Comparative results of WLS fibres produced by Bicron, Kuraray and Pol.Hi.Tech are presented. The performance of the fibres BCF91A from Bicron and S048 from Pol.Hi.Tech was significatively improved, but the most performant are still the double clad Y11 fibres from Kuraray.

  17. The structure of boron in boron fibres

    NASA Technical Reports Server (NTRS)

    Bhardwaj, J.; Krawitz, A. D.

    1983-01-01

    The structure of noncrystalline, chemically vapour-deposited boron fibres was investigated by computer modelling the experimentally obtained X-ray diffraction patterns. The diffraction patterns from the models were computed using the Debye scattering equation. The modelling was done utilizing the minimum nearest-neighbour distance, the density of the model, and the broadening and relative intensity of the various peaks as boundary conditions. The results suggest that the fibres consist of a continuous network of randomly oriented regions of local atomic order, about 2 nm in diameter, containing boron atoms arranged in icosahedra. Approximately half of these regions have a tetragonal structure and the remaining half a distorted rhombohedral structure. The model also indicates the presence of many partial icosahedra and loose atoms not associated with any icosahedra. The partial icosahedra and loose atoms indicated in the present model are in agreement with the relaxing sub-units which have been suggested to explain the anelastic behavior of fibre boron and the loosely bound boron atoms which have been postulated to explain the strengthening mechanism in boron fibres during thermal treatment.

  18. Two-frequency fibre Raman laser

    SciTech Connect

    Paramonov, Vladimir M; Kurkov, Andrei S; Medvedkov, O I; Grukh, Dmitrii A; Dianov, Evgenii M

    2004-03-31

    A new scheme of a fibre Raman laser emitting at two wavelengths is proposed. The scheme uses a one-stage Raman converter with the output Bragg grating with the reflectivity above 99%. Lasing at two wavelengths is achieved due to the overlap of the output emission spectrum with the reflection spectrum of the output Bragg grating. (lasers)

  19. Radiation curing of carbon fibre composites

    NASA Astrophysics Data System (ADS)

    Spadaro, G.; Alessi, S.; Dispenza, C.; Sabatino, M. A.; Pitarresi, G.; Tumino, D.; Przbytniak, G.

    2014-01-01

    Epoxy/carbon fibre reinforced composites were produced by means of e-beam irradiation through a pulsed 10 MeV electron beam accelerator. The matrix consisted of a difunctional epoxy monomer (DGEBA) and an initiator of cationic polymerisation, while the reinforcement was a unidirectional high modulus carbon fibre fabric. Dynamic mechanical thermal analysis was carried out in order to determine the cross-linking degree. The analysis pointed out a nonuniformity in the cross-linking degree of the e-beam cured panels, with the formation of clusters at low Tg (glass transition temperature) and clusters at high Tg. An out-of-mould post irradiation thermal treatment on e-beam cured samples provides a higher uniformity in the network although some slight degradation effects. Mode I delamination fracture toughness and Interlaminar Shear Strength (ISS) were also investigated by means of Double Cantilever Beam (DCB) and Short Beam Shear tests, respectively. Results from this mechanical characterisation allowed to correlate fracture toughness of the bulk matrix resin, cross-linking density and fibre/matrix interaction to the delamination fracture behaviour of the fibre reinforced material.

  20. Fibre optic grating sensors for biofuels

    NASA Astrophysics Data System (ADS)

    Muller, M.; Fabris, J. L.; Kalinowski, H. J.

    2010-09-01

    Biofuels will have more intense impact on the energetic grid of the planet, because known fossil fuels reserves are being exhausted. The biofuel production relies on the transformation process of some organic material in the desired hydrocarbon product. Because of the natural characteristics of the related processes, fibre optic sensors appear to be adequate candidates to be used.

  1. WEAVE MOS fibre bundle test plan

    NASA Astrophysics Data System (ADS)

    Sayède, Frédéric; Guinouard, Isabelle; Fasola, Gilles; Lhome, Emilie; Amans, Jean-Philippe; Bonifacio, Piercarlo; Abrams, Don Carlos; Middleton, Kevin; Dalton, Gavin; Aguerri, J. Alfonso L.; Trager, Scott C.; Loeb, Avi

    2014-07-01

    WEAVE is the next-generation wide-field optical spectroscopy facility for the William Herschel Telescope (WHT) in La Palma, Canary Islands, Spain. WEAVE mainly aims at spectroscopic follow-up of ground-based (e.g. LOFAR) and space-based (GAIA) surveys. The facility consists of a new 2-degree field-of-view prime focus corrector with a 1000- multiplex fibre positioner, a small number of individually deployable integral field units, and a large single integral field unit. The IFUs (Integral Field Units) and the MOS fibres can be used to feed a dual-beam spectrograph that will provide full coverage of the majority of the visible spectrum in a single exposure at a spectral resolution of ~5000 or modest wavelength coverage in both arms at a resolution ~20000. The instrument is expected to be on-sky by 2017 to provide spectroscopic sampling of the fainter end of the Gaia astrometric catalogue, chemical labeling of stars to V~17, and dedicated follow up of substantial numbers of sources from the medium deep LOFAR surveys. After a brief description of the MOS fibre bundle, we described the proposed test plan and the test bench of the 2x1000 WEAVE MOS fibres. The test bench allows us to evaluate the Focal Ratio Degradation and the throughput of the fibers fitted with their buttons and slitlets.

  2. Characterisation of graphene fibres and graphene coated fibres using capacitively coupled contactless conductivity detector.

    PubMed

    Cabot, Joan M; Duffy, Emer; Currivan, Sinéad; Ruland, Andres; Jalili, Rouhollah; Mozer, Attila J; Innis, Peter C; Wallace, Gordon G; Breadmore, Michael; Paull, Brett

    2016-04-25

    The use of capacitively coupled contactless conductivity detection (C(4)D) for the characterisation of thin conductive graphene fibres, graphene composite fibres, and graphene coated fibrous materials is demonstrated for the first time. Within a few seconds, the non-destructive C(4)D detector provides a profile of the longetudinal physical homogeneity of the fibre, as well as extra information regarding fibre mophology and composition. In addition to the theoretical considerations related to the factors affect the output signal, this work evaluates the properties of graphene fibres using scanning C(4)D following the manufacturing process of wet-spinning. Furthermore, conductive graphene-coated fibrous materials and the effectiveness of the coating and reduction procedures applied could be investigated. Apart from the application of C(4)D in the monitoring of such processes, the feasibility of this small, highly sensitive and rapidly-responsive detector to monitor strain and elasticity responses of conductive and elastomeric composite fibres for applications in motion sensing, biomedical monitoring, and stretchable electronics was also demonstrated. PMID:26911662

  3. Myofibrillar ATPase activity in skinned human skeletal muscle fibres: fibre type and temperature dependence.

    PubMed Central

    Stienen, G J; Kiers, J L; Bottinelli, R; Reggiani, C

    1996-01-01

    1. Myofibrillar ATP consumption and isometric tension (P0) were determined in chemically skinned skeletal muscle fibres from human rectus abdominis and vastus lateralis muscle. Fibres were classified in four groups (I, IIA, IIB, IIA/B or mixed) based on myosin heavy chain composition. 2. ATP consumption (+/- S.E.M.) at 20 degrees C varied from 0.41 +/- 0.06 mmol l-1 s-1 in type IIB fibres (n = 5) to 0.10 +/- 0.01 mmol l-1 s-1 in type I fibres (n = 13). 3. The ratio between ATPase activity and P0 (tension cost) differed significantly between fast type II and slow type I fibres. At 12 degrees C tension cost was lower than the values found previously in corresponding fibre types in the rat. 4. The relative increase in ATPase activity for a 10 degrees C temperature change (Q10), determined in the range from 12 to 30 degrees C, was temperature independent and amounted to 2.60 +/- 0.06. The increase in P0 with temperature was smaller and declined when the temperature increased. 5. From these measurements, estimates were obtained for the maximum rate of isometric ATP consumption and force development at muscle temperature in vivo (35 degrees C). Images Figure 1 PMID:8782097

  4. Optical properties of in-vitro biomineralised silica.

    PubMed

    Polini, Alessandro; Pagliara, Stefano; Camposeo, Andrea; Cingolani, Roberto; Wang, Xiaohong; Schröder, Heinz C; Müller, Werner E G; Pisignano, Dario

    2012-01-01

    Silicon is the second most common element on the Earth's crust and its oxide (SiO(2)) the most abundant mineral. Silica and silicates are widely used in medicine and industry as well as in micro- and nano-optics and electronics. However, the fabrication of glass fibres and components requires high temperature and non-physiological conditions, in contrast to biosilica structures in animals and plants. Here, we show for the first time the use of recombinant silicatein-α, the most abundant subunit of sponge proteins catalyzing biosilicification reactions, to direct the formation of optical waveguides in-vitro through soft microlithography. The artificial biosilica fibres mimic the natural sponge spicules, exhibiting refractive index values suitable for confinement of light within waveguides, with optical losses in the range of 5-10 cm(-1), suitable for application in lab-on-chips systems. This method extends biosilicification to the controlled fabrication of optical components by physiological processing conditions, hardly addressed by conventional technologies. PMID:22934130

  5. Optical properties of in-vitro biomineralised silica

    NASA Astrophysics Data System (ADS)

    Polini, Alessandro; Pagliara, Stefano; Camposeo, Andrea; Cingolani, Roberto; Wang, Xiaohong; Schröder, Heinz C.; Müller, Werner E. G.; Pisignano, Dario

    2012-08-01

    Silicon is the second most common element on the Earth's crust and its oxide (SiO2) the most abundant mineral. Silica and silicates are widely used in medicine and industry as well as in micro- and nano-optics and electronics. However, the fabrication of glass fibres and components requires high temperature and non-physiological conditions, in contrast to biosilica structures in animals and plants. Here, we show for the first time the use of recombinant silicatein-α, the most abundant subunit of sponge proteins catalyzing biosilicification reactions, to direct the formation of optical waveguides in-vitro through soft microlithography. The artificial biosilica fibres mimic the natural sponge spicules, exhibiting refractive index values suitable for confinement of light within waveguides, with optical losses in the range of 5-10 cm-1, suitable for application in lab-on-chips systems. This method extends biosilicification to the controlled fabrication of optical components by physiological processing conditions, hardly addressed by conventional technologies.

  6. Optical properties of in-vitro biomineralised silica

    PubMed Central

    Polini, Alessandro; Pagliara, Stefano; Camposeo, Andrea; Cingolani, Roberto; Wang, Xiaohong; Schröder, Heinz C.; Müller, Werner E. G.; Pisignano, Dario

    2012-01-01

    Silicon is the second most common element on the Earth's crust and its oxide (SiO2) the most abundant mineral. Silica and silicates are widely used in medicine and industry as well as in micro- and nano-optics and electronics. However, the fabrication of glass fibres and components requires high temperature and non-physiological conditions, in contrast to biosilica structures in animals and plants. Here, we show for the first time the use of recombinant silicatein-α, the most abundant subunit of sponge proteins catalyzing biosilicification reactions, to direct the formation of optical waveguides in-vitro through soft microlithography. The artificial biosilica fibres mimic the natural sponge spicules, exhibiting refractive index values suitable for confinement of light within waveguides, with optical losses in the range of 5–10 cm−1, suitable for application in lab-on-chips systems. This method extends biosilicification to the controlled fabrication of optical components by physiological processing conditions, hardly addressed by conventional technologies. PMID:22934130

  7. Surface Treated Natural Fibres as Filler in Biocomposites

    NASA Astrophysics Data System (ADS)

    Schwarzova, I.; Stevulova, N.; Singovszka, E.; Terpakova, E.

    2015-11-01

    Biocomposites based on natural fibres as organic filler have been studied for several years because traditional building materials such as concrete are increasingly being replaced by advanced composite materials. Natural fibres are a potential replacement of glass fibres in composite materials. Inherent advantages such as low density, biodegradability and comparable specific mechanical properties make natural fibres an attractive option. However, limitations such as poor thermal stability, moisture absorption and poor compatibility with matrix are challenges that need to be resolved. The primary objective of this research was to study the effect of surface treatment on properties of hemp hurds like a natural lignocellulosic material and composites made thereof. Industrial hemp fibre is the one of the most suitable fibres for use in composite materials because of its good specific properties, as well as it being biologically degradable and CO2 neutral. Improving interfacial bonding between fibres and matrix is an important factor in using hemp fibres as reinforcement in composites. In order to improve interfacial bonding, modifications can be made to the hemp fibres to remove non- cellulosic compounds, separate hemp fibres from their bundles, and modify the fibre surface. This paper contains the comparison of FTIR spectra caused by combination of physical and chemical treatment of hemp material with unmodified sample. Modification of hemp hurds was carried out by NaOH solution and by ultrasonic treatment (deionized water and NaOH solution were used as the cleaning mediums).

  8. Longitudinal fibre splitting in muscular dystrophy: a serial cinematographic study

    PubMed Central

    Isaacs, Edward R.; Bradley, Walter G.; Henderson, Gerald

    1973-01-01

    A technique of block surface-staining and serial cinematography was modified to review serial sections of normal and dystrophic muscle from the Bar Harbor 129 Re strain of mice as a preliminary study of fibre splitting in dystrophic muscle. Using this technique, muscle fibres were reconstructed for up to 1·5 mm of their length without difficulty. Split fibres were identified only when the actual separation of fibres was observed. Splitting was seen to be a significant cause of the variations in fibre diameter and was at times responsible for the formation of groups of small atrophic fibres which resembled those seen in denervation atrophy. Complex multiple splitting and recombination of daughter and parent fibres was also observed and reconstructed to scale. These results may have considerable significance for the interpretation of physiological data on both human and murine dystrophic muscle. Images PMID:4753877

  9. Optical fibre-based detection of DNA hybridization.

    PubMed

    Hine, Anna V; Chen, Xianfeng; Hughes, Marcus D; Zhou, Kaiming; Davies, Edward; Sugden, Kate; Bennion, Ian; Zhang, Lin

    2009-04-01

    A dual-peak LPFG (long-period fibre grating), inscribed in an optical fibre, has been employed to sense DNA hybridization in real time, over a 1 h period. One strand of the DNA was immobilized on the fibre, while the other was free in solution. After hybridization, the fibre was stripped and repeated detection of hybridization was achieved, so demonstrating reusability of the device. Neither strand of DNA was fluorescently or otherwise labelled. The present paper will provide an overview of our early-stage experimental data and methodology, examine the potential of fibre gratings for use as biosensors to monitor both nucleic acid and other biomolecular interactions and then give a summary of the theory and fabrication of fibre gratings from a biological standpoint. Finally, the potential of improving signal strength and possible future directions of fibre grating biosensors will be addressed. PMID:19290879

  10. Scanning electron microscopy of Purkinje fibres of the pig heart.

    PubMed

    Bytzer, P

    1979-01-01

    Scanning electron microscopy (SEM) of Purkinje fibres (P-fibres) from the septal walls and the septomarginal trabecula was performed on deparaffinized sections, the identification in SEM made possible by comparative light microscopy. The myofibrils in P-fibres from the septal walls were arranged in a cart-wheel fashion, whereas P-fibres from the septomarginal trabecula showed a nearly parallel alignment of the contractile material. Z-line ridges resembling the T-tubules of the myocardial fibres were observed in both kinds of P-fibres. The myofibrillar arrangements are discussed in relation to the expected mechanical stress put upon P-fibres in the 2 locations during systolic-diastolic activity. An adaptive function of the contractile material to the mechanical stress is suggested and the possible need of a T-tubular system is discussed. PMID:507370

  11. Hierarchically arranged helical fibre actuators driven by solvents and vapours

    NASA Astrophysics Data System (ADS)

    Chen, Peining; Xu, Yifan; He, Sisi; Sun, Xuemei; Pan, Shaowu; Deng, Jue; Chen, Daoyong; Peng, Huisheng

    2015-12-01

    Mechanical responsiveness in many plants is produced by helical organizations of cellulose microfibrils. However, simple mimicry of these naturally occurring helical structures does not produce artificial materials with the desired tunable actuations. Here, we show that actuating fibres that respond to solvent and vapour stimuli can be created through the hierarchical and helical assembly of aligned carbon nanotubes. Primary fibres consisting of helical assemblies of multiwalled carbon nanotubes are twisted together to form the helical actuating fibres. The nanoscale gaps between the nanotubes and micrometre-scale gaps among the primary fibres contribute to the rapid response and large actuation stroke of the actuating fibres. The compact coils allow the actuating fibre to rotate reversibly. We show that these fibres, which are lightweight, flexible and strong, are suitable for a variety of applications such as energy-harvesting generators, deformable sensing springs and smart textiles.

  12. Analysis on fibre orientation of thermal bonded nonwoven

    NASA Astrophysics Data System (ADS)

    Musa, Atiyyah; Gong, Rong Hugh; Nasir, Eryna; Baharudin, Aznin; Tulos, Najua

    2016-02-01

    The aim of this research is to produce some three-dimensional (3D) nonwoven fabrics with variation in weight and type of fibre and then analyse their fibre orientation distribution by fast Fourier Transform (FFT) method. Three different fibres were used: polyester, polypropylene and blended polyester and polypropylene. Fabric weight varied from 20 to 180 g/m2. The processes of web formation and consolidation were based on the principle of air-laid and hot through-air thermal bonding technique. The result of the fibre orientation showed a random distribution of the fibres for all the samples. It indicated that there was no relationship between the variables and fibre orientation distribution. The position of 3D web whether from the top or side part did not show any variation and thus they did not have the influence towards the fibre orientation.

  13. Histochemical type I fibres in the soleus of the rat.

    PubMed

    Dekleva, A; Sirca, A

    1978-12-01

    Based on oxidative enzyme activity levels, fibres exhibiting moderate and high levels may be identified in the soleus of the rat. Fibres showing moderate activity are classified as Type I fibres, while those showing high activity may belong to Type I or Type II. According to the level of ATPase activity in fixed sections, we can distinguish three types of fibres in the soleus of the rat (IA, IB and II) and, by application of acid pre-incubation, also sub-classes of Type II (IIA and IIC). Type IB fibres possess high oxidative and glycolytic enzyme activities, moderate ATPase activity after fixation, and behave in the same way as Type I fibres after alkaline and acid pre-incubation. For the histochemical classificationof fibre types, we should consider not only reactions to ATPase, and after acid pre-incubation, but also reactions to the enzymes of oxidative and glycolytic metabolism. PMID:154494

  14. Histochemical type I fibres in the soleus of the rat.

    PubMed Central

    Dekleva, A; Sirca, A

    1978-01-01

    Based on oxidative enzyme activity levels, fibres exhibiting moderate and high levels may be identified in the soleus of the rat. Fibres showing moderate activity are classified as Type I fibres, while those showing high activity may belong to Type I or Type II. According to the level of ATPase activity in fixed sections, we can distinguish three types of fibres in the soleus of the rat (IA, IB and II) and, by application of acid pre-incubation, also sub-classes of Type II (IIA and IIC). Type IB fibres possess high oxidative and glycolytic enzyme activities, moderate ATPase activity after fixation, and behave in the same way as Type I fibres after alkaline and acid pre-incubation. For the histochemical classificationof fibre types, we should consider not only reactions to ATPase, and after acid pre-incubation, but also reactions to the enzymes of oxidative and glycolytic metabolism. Images Fig. 1 Fig. 2 PMID:154494

  15. Hierarchically arranged helical fibre actuators driven by solvents and vapours.

    PubMed

    Chen, Peining; Xu, Yifan; He, Sisi; Sun, Xuemei; Pan, Shaowu; Deng, Jue; Chen, Daoyong; Peng, Huisheng

    2015-12-01

    Mechanical responsiveness in many plants is produced by helical organizations of cellulose microfibrils. However, simple mimicry of these naturally occurring helical structures does not produce artificial materials with the desired tunable actuations. Here, we show that actuating fibres that respond to solvent and vapour stimuli can be created through the hierarchical and helical assembly of aligned carbon nanotubes. Primary fibres consisting of helical assemblies of multiwalled carbon nanotubes are twisted together to form the helical actuating fibres. The nanoscale gaps between the nanotubes and micrometre-scale gaps among the primary fibres contribute to the rapid response and large actuation stroke of the actuating fibres. The compact coils allow the actuating fibre to rotate reversibly. We show that these fibres, which are lightweight, flexible and strong, are suitable for a variety of applications such as energy-harvesting generators, deformable sensing springs and smart textiles. PMID:26367106

  16. Generation of 25-ns pulses with a peak power of over 10 kW from a gain-switched, 2-mm Tm-doped fibre laser and amplifier system

    SciTech Connect

    Swiderski, J; Michalska, M; Pichola, W; Mamajek, M

    2014-04-28

    We report on an all-fibre, gain-switched, Tm{sup 3+}-doped silica fibre laser and amplifier system generating a train of pulses at a wavelength of 1994.4 nm. When operating at a pulse repetition frequency f=''100'' kHz, it delivered the maximum average power as high as 9.03 W with a slope efficiency of 36.4%. At f = 26 kHz, stable 25-ns pulses with an energy of 0.28 mJ corresponding to a peak power of 10.5 kW were obtained. The performance of the laser system is described. (lasers)

  17. Silica research in Glasgow

    NASA Astrophysics Data System (ADS)

    Barr, B. W.; Cagnoli, G.; Casey, M. M.; Clubley, D.; Crooks, D. R. M.; Danzmann, K.; Elliffe, E. J.; Goßler, S.; Grant, A.; Grote, H.; Heptonstall, A.; Hough, J.; Jennrich, O.; Lück, H.; McIntosh, S. A.; Newton, G. P.; Palmer, D. A.; Plissi, M. V.; Robertson, D. I.; Robertson, N. A.; Rowan, S.; Skeldon, K. D.; Sneddon, P.; Strain, K. A.; Torrie, C. I.; Ward, H.; Willems, P. A.; Willke, B.; Winkler, W.

    2002-04-01

    The Glasgow group is involved in the construction of the GEO600 interferometer as well as in R&D activity on technology for advanced gravitational wave detectors. GEO600 will be the first GW detector using quasi-monolithic silica suspensions in order to decrease thermal noise significantly with respect to steel wire suspensions. The results concerning GEO600 suspension mounting and performance will be shown in the first section. Section 2 is devoted to the present results from the direct measurement of thermal noise in mirrors mounted in the 10 m interferometer in Glasgow which has a sensitivity limit of 4 × 10-19 m Hz-1/2 above 1 kHz. Section 3 presents results on the measurements of coating losses. R&D activity has been carried out to understand better how thermal noise in the suspensions affects the detector sensitivity, and in section 4 a discussion on the non-linear thermoelastic effect is presented.

  18. Development of a novel cellulose/duck feather composite fibre regenerated in ionic liquid.

    PubMed

    De Silva, Rasike; Wang, Xungai; Byrne, Nolene

    2016-11-20

    By blending cellulose and duck feather in the common solvent 1-allyl-3-methylimidazoloium chloride, a regenerated composite fibre has been developed with improved fibres over regenerated cellulose fibres (RCF). The mechanical properties of composite fibre was shown to be better than RCF with a 63.7% improvement in tensile strain. Here, we thoroughly characterise the composite fibre and show that the composite fibre has many advantages over RCFs both from a spinning perspective and as a regenerated fibre. PMID:27561478

  19. Muscle fibre types in the suprahyoid muscles of the rat

    PubMed Central

    COBOS, A. R.; SEGADE, L. A. G.; FUENTES, I.

    2001-01-01

    Five muscle fibre types (I, IIc, IIa, IIx and IIb) were found in the suprahyoid muscles (mylohyoid, geniohyoid, and the anterior and posterior bellies of the digastric) of the rat using immuno and enzyme histochemical techniques. More than 90% of fibres in the muscles examined were fast contracting fibres (types IIa, IIx and IIb). The geniohyoid and the anterior belly of the digastric had the greatest number of IIb fibres, whilst the mylohyoid was almost exclusively formed by aerobic fibres. The posterior belly of the digastric contained a greater percentage of aerobic fibres (83.4%) than the anterior belly (67.8%). With the exception of the geniohyoid, the percentage of type I and IIc fibres, which have slow myosin heavy chain (MHCβ), was relatively high and greater than has been previously reported in the jaw-closing muscles of the rat, such as the superficial masseter. The geniohyoid and mylohyoid exhibited a mosaic fibre type distribution, without any apparent regionalisation, although in the later MHCβ-containing fibres (types I and IIc) were primarily located in the rostral 2/3 region. In contrast, the anterior and posterior bellies of the digastric revealed a clear regionalisation. In the anterior belly of the digastric 2 regions were observed: both a central region, which was almost exclusively formed by aerobic fibres and where all of the type I and IIc fibres were located, and a peripheral region, where type IIb fibres predominated. The posterior belly of the digastric showed a deep aerobic region which was greater in size and where type I and IIc fibres were confined, and a superficial region, where primarily type IIx and IIb fibres were observed. PMID:11322721

  20. 21 CFR 584.700 - Hydrophobic silicas.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Hydrophobic silicas. 584.700 Section 584.700 Food... DRINKING WATER OF ANIMALS Listing of Specific Substances Affirmed as GRAS § 584.700 Hydrophobic silicas. (a) Product. Amorphous fumed hydrophobic silica or precipitated hydrophobic silica (CAS Reg. No....

  1. 21 CFR 584.700 - Hydrophobic silicas.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Hydrophobic silicas. 584.700 Section 584.700 Food... DRINKING WATER OF ANIMALS Listing of Specific Substances Affirmed as GRAS § 584.700 Hydrophobic silicas. (a) Product. Amorphous fumed hydrophobic silica or precipitated hydrophobic silica (CAS Reg. No....

  2. 21 CFR 584.700 - Hydrophobic silicas.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Hydrophobic silicas. 584.700 Section 584.700 Food... DRINKING WATER OF ANIMALS Listing of Specific Substances Affirmed as GRAS § 584.700 Hydrophobic silicas. (a) Product. Amorphous fumed hydrophobic silica or precipitated hydrophobic silica (CAS Reg. No....

  3. 21 CFR 584.700 - Hydrophobic silicas.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Hydrophobic silicas. 584.700 Section 584.700 Food... DRINKING WATER OF ANIMALS Listing of Specific Substances Affirmed as GRAS § 584.700 Hydrophobic silicas. (a) Product. Amorphous fumed hydrophobic silica or precipitated hydrophobic silica (CAS Reg. No....

  4. 21 CFR 582.1711 - Silica aerogel.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Silica aerogel. 582.1711 Section 582.1711 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS....1711 Silica aerogel. (a) Product. Silica aerogel as a finely powdered microcellular silica foam...

  5. 21 CFR 182.1711 - Silica aerogel.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Silica aerogel. 182.1711 Section 182.1711 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN....1711 Silica aerogel. (a) Product. Silica aerogel as a finely powdered microcellular silica foam...

  6. Silica/Polymer and Silica/Polymer/Fiber Composite Aerogels

    NASA Technical Reports Server (NTRS)

    Ou, Danny; Stepanian, Christopher J.; Hu, Xiangjun

    2010-01-01

    Aerogels that consist, variously, of neat silica/polymer alloys and silica/polymer alloy matrices reinforced with fibers have been developed as materials for flexible thermal-insulation blankets. In comparison with prior aerogel blankets, these aerogel blankets are more durable and less dusty. These blankets are also better able to resist and recover from compression . an important advantage in that maintenance of thickness is essential to maintenance of high thermal-insulation performance. These blankets are especially suitable as core materials for vacuum- insulated panels and vacuum-insulated boxes of advanced, nearly seamless design. (Inasmuch as heat leakage at seams is much greater than heat leakage elsewhere through such structures, advanced designs for high insulation performance should provide for minimization of the sizes and numbers of seams.) A silica/polymer aerogel of the present type could be characterized, somewhat more precisely, as consisting of multiply bonded, linear polymer reinforcements within a silica aerogel matrix. Thus far, several different polymethacrylates (PMAs) have been incorporated into aerogel networks to increase resistance to crushing and to improve other mechanical properties while minimally affecting thermal conductivity and density. The polymethacrylate phases are strongly linked into the silica aerogel networks in these materials. Unlike in other organic/inorganic blended aerogels, the inorganic and organic phases are chemically bonded to each other, by both covalent and hydrogen bonds. In the process for making a silica/polymer alloy aerogel, the covalent bonds are introduced by prepolymerization of the methacrylate monomer with trimethoxysilylpropylmethacrylate, which serves as a phase cross-linker in that it contains both organic and inorganic monomer functional groups and hence acts as a connector between the organic and inorganic phases. Hydrogen bonds are formed between the silanol groups of the inorganic phase and the

  7. Acoustical model of a Shoddy fibre absorber

    NASA Astrophysics Data System (ADS)

    Manning, John Peter

    Shoddy fibres or "Shoddies" are a mixture of post-consumer and post-industrial fibres diverted from textile waste streams and recycled into their raw fibre form. They have found widespread use as a raw material for manufacturing sound absorbers that include, but are not limited to: automotive, architectural and home appliance applications. The purpose of this project is to develop a simple acoustic model to describe the acoustic behaviour of sound absorbers composed primarily of Shoddy fibres. The model requires knowledge of the material's bulk density only. To date, these materials have not been the focus of much published research and acoustical designers must rely on models that were developed for other materials or are overly complex. For modelling purposes, an equivalent fluid approach is chosen to balance complexity and accuracy. In deriving the proposed model, several popular equivalent fluid models are selected and the required input parameters for each model identified. The models are: the model of Delaney and Bazley, two models by Miki, the model of Johnson in conjunction with the model of Champoux and Allard and the model of Johnson in conjunction with the model of Lafarge. Characterization testing is carried out on sets of Shoddy absorbers produced using three different manufacturing methods. The measured properties are open porosity, tortuosity, airflow resistivity, the viscous and thermal characteristic lengths and the static thermal permeability. Empirical relationships between model parameters and bulk density are then derived and used to populate the selected models. This yields several 'simplified' models with bulk density as the only parameter. The most accurate model is then selected by comparing each model's prediction to the results of normal incidence sound absorption tests. The model of Johnson-Lafarge populated with the empirical relations is the most accurate model over the range of frequencies considered (approx. 300 Hz - 4000 Hz

  8. Skin penetration of silica microparticles.

    PubMed

    Boonen, J; Baert, B; Lambert, J; De Spiegeleer, B

    2011-06-01

    Knowledge about skin penetration of nano- and microparticles is essential for the development of particle-core drug delivery systems and toxicology. A large number of studies have been devoted to metallic particle penetration. However, little work has been published about the importance of chemical material properties of the particles and the skin penetration effect of the applied formulation. Here, we investigated the penetration of 3 microm silica particles in water and in a 65% ethanolic plant extract on ex vivo human skin using scanning electron microscopy. Contrary to most other microsphere skin studies, we observed for the first time that 3 microm silica particles can penetrate the living epidermis. Moreover, when formulated in the ethanolic medium, particles even reach the dermis. The deviating chemical properties of silica compared to previously investigated microparticles (titanium dioxide, zinc oxide) and confounding effect of the formulation in which the silica microparticles are presented, is thus demonstrated. PMID:21699089

  9. Strength and toughness of structural fibres for composite material reinforcement.

    PubMed

    Herráez, M; Fernández, A; Lopes, C S; González, C

    2016-07-13

    The characterization of the strength and fracture toughness of three common structural fibres, E-glass, AS4 carbon and Kevlar KM2, is presented in this work. The notched specimens were prepared by means of selective carving of individual fibres by means of the focused ion beam. A straight-fronted edge notch was introduced in a plane perpendicular to the fibre axis, with the relative notch depth being a0/D≈0.1 and the notch radius at the tip approximately 50 nm. The selection of the appropriate beam current during milling operations was performed to avoid to as much as possible any microstructural changes owing to ion impingement. Both notched and un-notched fibres were submitted to uniaxial tensile tests up to failure. The strength of the un-notched fibres was characterized in terms of the Weibull statistics, whereas the residual strength of the notched fibres was used to determine their apparent toughness. To this end, the stress intensity factor of a fronted edge crack was computed by means of the finite-element method for different crack lengths. The experimental results agreed with those reported in the literature for polyacrylonitrile-based carbon fibres obtained by using similar techniques. After mechanical testing, the fracture surface of the fibres was analysed to ascertain the failure mechanisms. It was found that AS4 carbon and E-glass fibres presented the lower toughness with fracture surfaces perpendicular to the fibre axis, emanating from the notch tip. The fractured region of Kevlar KM2 fibres extended along the fibre and showed large permanent deformation, which explains their higher degree of toughness when compared with carbon and glass fibres. This article is part of the themed issue 'Multiscale modelling of the structural integrity of composite materials'. PMID:27242306

  10. Fibre laser component technology for 2-micron laser systems

    NASA Astrophysics Data System (ADS)

    Stevens, G.; Robertson, A.

    2014-05-01

    We report on recent developments in fibre laser component technology for use in 2-micron laser systems. A range of `building block' components has been built to allow novel fibre laser architectures that exploit the advantages of fibre lasers based on Thulium and Holmium active fibres. Fibre lasers operating around 2-microns are becoming widely used in an increasing number of applications, which is driving the need for components that can operate reliably at high powers and also integrate easily with other components. To that end, we have designed and built a range of fused fibre, acousto-optic and magneto-optic devices that can be readily integrated into a range of novel fibre laser systems. Research has been carried out into improving fused fibre technology for components operating at 2um wavelengths. Side-coupled feed through combiners have been developed with signal losses as low as 0.02dB and kilowatt level end-coupled pump couplers. Alongside this a range of taps, splitters and WDMs have been developed which allows for the implementation of a variety of laser architectures. Optical isolators based on new Faraday materials have been developed, providing over 30dB isolation, low insertion loss and 30W power handling in a fibre-in, fibre-out version. New cell designs and materials for Acousto-Optic devices have been researched leading to the development of fibre-coupled Acousto-Optic Modulators (AOM) and allows for the realisation of all fibre Thulium and Holmium Q-switched and pulsed fibre lasers. Novel Acousto-Optic Tunable Filters (AOTF) designs have been realised to produce narrow resolution AOTFs and zero-shift AOTFs.

  11. Polymerizing the fibre between bacteria and host cells: the biogenesis of functional amyloid fibres

    PubMed Central

    Epstein, Elisabeth Ashman; Chapman, Matthew R.

    2009-01-01

    Summary Amyloid fibres are proteinaceous aggregates associated with several human diseases, including Alzheimer’s, Huntington’s and Creutzfeldt Jakob’s. Disease-associated amyloid formation is the result of proteins that misfold and aggregate into β sheet-rich fibre polymers. Cellular toxicity is readily associated with amyloidogenesis, although the molecular mechanism of toxicity remains unknown. Recently, a new class of ‘functional’ amyloid fibres was discovered that demonstrates that amyloids can be utilized as a productive part of cellular biology. These functional amyloids will provide unique insights into how amyloid formation can be controlled and made less cytotoxic. Bacteria produce some of the best-characterized functional amyloids, including a surface amyloid fibre called curli. Assembled by enteric bacteria, curli fibres mediate attachment to surfaces and host tissues. Some bacterial amyloids, like harpins and microcinE492, have exploited amyloid toxicity in a directed and functional manner. Here, we review and discuss the functional amyloids assembled by bacteria. Special emphasis will be paid to the biology of functional amyloid synthesis and the connections between bacterial physiology and pathology. PMID:18373633

  12. A viscoelastic-viscoplastic model for short-fibre reinforced polymers with complex fibre orientations

    NASA Astrophysics Data System (ADS)

    Nciri, M.; Notta-Cuvier, D.; Lauro, F.; Chaari, F.; Zouari, B.; Maalej, Y.

    2015-09-01

    This paper presents an innovative approach for the modelling of viscous behaviour of short-fibre reinforced composites (SFRC) with complex distributions of fibre orientations and for a wide range of strain rates. As an alternative to more complex homogenisation methods, the model is based on an additive decomposition of the state potential for the computation of composite's macroscopic behaviour. Thus, the composite material is seen as the assembly of a matrix medium and several linear elastic fibre media. The division of short fibres into several families means that complex distributions of orientation or random orientation can be easily modelled. The matrix behaviour is strain-rate sensitive, i.e. viscoelastic and/or viscoplastic. Viscoelastic constitutive laws are based on a generalised linear Maxwell model and the modelling of the viscoplasticity is based on an overstress approach. The model is tested for the case of a polypropylene reinforced with short-glass fibres with distributed orientations and subjected to uniaxial tensile tests, in different loading directions and under different strain rates. Results demonstrate the efficiency of the model over a wide range of strain rates.

  13. Self-Q-switched ytterbium-doped fibre laser with intracavity spectral conversion

    SciTech Connect

    Grukh, Dmitrii A; Levchenko, A E; Kurkov, Andrei S; Paramonov, Vladimir M

    2005-05-31

    A pulsed fibre laser is fabricated which is based on an active fibre with a multielement cladding and an additional single-mode fibre providing nonlinear feedback. The peak output power of the laser is {approx}1 kW for 20-ns pulses. The emission spectra of the laser with additional fibres having different nonlinear and dispersion properties are investigated. (fibre lasers)

  14. Fibre Optic Sensors for Selected Wastewater Characteristics

    PubMed Central

    Chong, Su Sin; Abdul Aziz, A. R.; Harun, Sulaiman W.

    2013-01-01

    Demand for online and real-time measurements techniques to meet environmental regulation and treatment compliance are increasing. However the conventional techniques, which involve scheduled sampling and chemical analysis can be expensive and time consuming. Therefore cheaper and faster alternatives to monitor wastewater characteristics are required as alternatives to conventional methods. This paper reviews existing conventional techniques and optical and fibre optic sensors to determine selected wastewater characteristics which are colour, Chemical Oxygen Demand (COD) and Biological Oxygen Demand (BOD). The review confirms that with appropriate configuration, calibration and fibre features the parameters can be determined with accuracy comparable to conventional method. With more research in this area, the potential for using FOS for online and real-time measurement of more wastewater parameters for various types of industrial effluent are promising. PMID:23881131

  15. Multiphoton absorption in amyloid protein fibres

    NASA Astrophysics Data System (ADS)

    Hanczyc, Piotr; Samoc, Marek; Norden, Bengt

    2013-12-01

    Fibrillization of peptides leads to the formation of amyloid fibres, which, when in large aggregates, are responsible for diseases such as Alzheimer's and Parkinson's. Here, we show that amyloids have strong nonlinear optical absorption, which is not present in native non-fibrillized protein. Z-scan and pump-probe experiments indicate that insulin and lysozyme β-amyloids, as well as α-synuclein fibres, exhibit either two-photon, three-photon or higher multiphoton absorption processes, depending on the wavelength of light. We propose that the enhanced multiphoton absorption is due to a cooperative mechanism involving through-space dipolar coupling between excited states of aromatic amino acids densely packed in the fibrous structures. This finding will provide the opportunity to develop nonlinear optical techniques to detect and study amyloid structures and also suggests that new protein-based materials with sizable multiphoton absorption could be designed for specific applications in nanotechnology, photonics and optoelectronics.

  16. Extreme electronic bandgap modification in laser-crystallized silicon optical fibres.

    PubMed

    Healy, Noel; Mailis, Sakellaris; Bulgakova, Nadezhda M; Sazio, Pier J A; Day, Todd D; Sparks, Justin R; Cheng, Hiu Y; Badding, John V; Peacock, Anna C

    2014-12-01

    For decades now, silicon has been the workhorse of the microelectronics revolution and a key enabler of the information age. Owing to its excellent optical properties in the near- and mid-infrared, silicon is now promising to have a similar impact on photonics. The ability to incorporate both optical and electronic functionality in a single material offers the tantalizing prospect of amplifying, modulating and detecting light within a monolithic platform. However, a direct consequence of silicon's transparency is that it cannot be used to detect light at telecommunications wavelengths. Here, we report on a laser processing technique developed for our silicon fibre technology through which we can modify the electronic band structure of the semiconductor material as it is crystallized. The unique fibre geometry in which the silicon core is confined within a silica cladding allows large anisotropic stresses to be set into the crystalline material so that the size of the bandgap can be engineered. We demonstrate extreme bandgap reductions from 1.11 eV down to 0.59 eV, enabling optical detection out to 2,100 nm. PMID:25262096

  17. Physico-chemical properties of organically modified silicates' sol-gel layers for optical fibre sensors

    NASA Astrophysics Data System (ADS)

    Chodkowska, Eliza; Rayss, Jan

    2006-10-01

    The paper concerns the investigation of modified silica gel materials applied in optical fibre sensors. These materials are products of a sol-gel process in which three kinds of alkoxysilanes undergo hydrolysis and condensation and may play a role of the matrices containing transducer's molecules in the active layer of the sensor. In the experiment presented below three different compositions comprising tetraethoxysilane (TEOS), methyltriethoxysilane (MTES) and phenyltriethoxysilane (PhTES) were used. The alkoxysilanes underwent hydrolysis and condensation and the obtained gels were investigated in order to determine their texture, strucuture, composition and chemical properties as far as the dependence of those characteristics on the hydrolysis time and the molar ratio of the ingredients in the initial sols. The methods employed in the experiment were: Atomic Force Microscopy (AFM) which delivered vital information about the gels' textures, contact angles' and surface charge's measurements serving to estimate chemical properties of the gels' surfaces, Nuclear Magnetic Resonance (NMR) which helped to evaluate the hydrolysis' rate and porosimetric measurements enabling a determination of BET surface area and average diametres of the pores. The results may occur important for improving the construction of optical fibre sensors in which organically modified silicates (ORMOSILs)-TEOS layes are used.

  18. Use of nanoclay to improve the fire performance of glass fibre composites

    NASA Astrophysics Data System (ADS)

    Nguyen, Q.; Ngo, T.; Moinuddin, K.; Mendis, P.

    2013-08-01

    There is an urgent need to improve the fire performance of fibre composites so that they can be used in infrastructure applications. Nanoparticles from clay has been well known as a potential precursor of nanocomposites because of the significant improvement in mechanical properties and their availability. Nanoclay contains very thin layers of silicates, in which the octahedral sheet of alumina is sandwiched between two tetrahedral sheets of silica. Montmorillonite (MMT) nanoclay, the most widely used type, is often treated with cation-organic surfactants to render it organophilic. The addition of 3-5% organophilic clay into polymeric matrix can enhance the mechanical and thermal performance of the nanocomposite. Most research projects on clay nanocomposites were carried out with more focus on their improvement of mechanical properties. However, the effect of nanoclay on the fire performance of hybrid composites has not been covered comprehensively. In this study, the effect of organoclay on the fire performance of the hybrid nanocomposite was investigated. Epoxy and glass fibre reinforcement were chosen as they have been proven to be more suitable and feasible for civil infrastructure applications. The fire characteristics of the hybrid nanocomposite were evaluated using cone calorimeter tests conducted according to ISO 5660-1.

  19. Fibre tip pH sensor for tumor detection during surgery

    NASA Astrophysics Data System (ADS)

    Henderson, Matthew R.; Schartner, Erik P.; Callen, David F.; Gill, P. Grantley; Monro, Tanya M.

    2015-05-01

    Surgery on tumours commonly involves a lumpectomy method, where a section of tissue containing the tumour is removed, to improve cosmetic outcomes and quality of life. Following surgery, the margins of the removed section are checked by pathology tests to ensure that the entire tumour has been removed. Unfortunately, approximately 15-20% of margins show incomplete removal and require a subsequent operation to remove the remaining tumour. Tumour detection during surgery could allow the removed section to be enlarged appropriately, reducing the likelihood of requiring subsequent surgery. A change in the extracellular pH in the vicinity of a tumour, when compared to normal tissue, has been shown previously in literature. We have fabricated an optical fibre tip pH sensor by embedding a fluorophore within a photopolymerised acrylamide polymer on the tip of a 200 micron diameter silica fibre. Preliminary measurements of human melanoma samples have shown a significant difference in the measured pH values between tumour and normal tissue. This demonstration paves to way to highly accurate margin detection during surgery.

  20. Extreme electronic bandgap modification in laser-crystallized silicon optical fibres

    NASA Astrophysics Data System (ADS)

    Healy, Noel; Mailis, Sakellaris; Bulgakova, Nadezhda M.; Sazio, Pier J. A.; Day, Todd D.; Sparks, Justin R.; Cheng, Hiu Y.; Badding, John V.; Peacock, Anna C.

    2014-12-01

    For decades now, silicon has been the workhorse of the microelectronics revolution and a key enabler of the information age. Owing to its excellent optical properties in the near- and mid-infrared, silicon is now promising to have a similar impact on photonics. The ability to incorporate both optical and electronic functionality in a single material offers the tantalizing prospect of amplifying, modulating and detecting light within a monolithic platform. However, a direct consequence of silicon’s transparency is that it cannot be used to detect light at telecommunications wavelengths. Here, we report on a laser processing technique developed for our silicon fibre technology through which we can modify the electronic band structure of the semiconductor material as it is crystallized. The unique fibre geometry in which the silicon core is confined within a silica cladding allows large anisotropic stresses to be set into the crystalline material so that the size of the bandgap can be engineered. We demonstrate extreme bandgap reductions from 1.11 eV down to 0.59 eV, enabling optical detection out to 2,100 nm.

  1. Scalable synthesis of hierarchically structured carbon nanotube-graphene fibres for capacitive energy storage

    NASA Astrophysics Data System (ADS)

    Yu, Dingshan; Goh, Kunli; Wang, Hong; Wei, Li; Jiang, Wenchao; Zhang, Qiang; Dai, Liming; Chen, Yuan

    2014-07-01

    Micro-supercapacitors are promising energy storage devices that can complement or even replace batteries in miniaturized portable electronics and microelectromechanical systems. Their main limitation, however, is the low volumetric energy density when compared with batteries. Here, we describe a hierarchically structured carbon microfibre made of an interconnected network of aligned single-walled carbon nanotubes with interposed nitrogen-doped reduced graphene oxide sheets. The nanomaterials form mesoporous structures of large specific surface area (396 m2 g-1) and high electrical conductivity (102 S cm-1). We develop a scalable method to continuously produce the fibres using a silica capillary column functioning as a hydrothermal microreactor. The resultant fibres show a specific volumetric capacity as high as 305 F cm-3 in sulphuric acid (measured at 73.5 mA cm-3 in a three-electrode cell) or 300 F cm-3 in polyvinyl alcohol (PVA)/H3PO4 electrolyte (measured at 26.7 mA cm-3 in a two-electrode cell). A full micro-supercapacitor with PVA/H3PO4 gel electrolyte, free from binder, current collector and separator, has a volumetric energy density of ~6.3 mWh cm-3 (a value comparable to that of 4 V-500 µAh thin-film lithium batteries) while maintaining a power density more than two orders of magnitude higher than that of batteries, as well as a long cycle life. To demonstrate that our fibre-based, all-solid-state micro-supercapacitors can be easily integrated into miniaturized flexible devices, we use them to power an ultraviolet photodetector and a light-emitting diode.

  2. Fibre tracking: probabilistic approach and preliminary results

    NASA Astrophysics Data System (ADS)

    Torresin, A.; Moscato, A.; Minella, M.; Cardinale, F.; Minati, L.; Aquino, D.

    2009-01-01

    The aim of this work is to have a preliminary experience with probabilistic tractography. We performed fibres reconstruction for three tracts of interest with data obtained from two MR imaging units equipped with different gradients system. An acquisition protocol optimization has been necessary in order to obtain a good trade-off between image quality and data collection time. Possible solutions to acquisition and processing problems are discussed. Future developments and possible applications in neurosurgery are also suggested.

  3. Fibre optic sensors for mine hazard detection

    NASA Astrophysics Data System (ADS)

    Liu, T.; Wang, C.; Wei, Y.; Zhao, Y.; Huo, D.; Shang, Y.; Wang, Z.; Ning, Y.

    2009-07-01

    We report the development of a comprehensive safety monitoring solution for coal mines. A number of fibre optic sensors have been developed and deployed for safety monitoring of mine roof integrity and hazardous gases. The FOS-based mine hazard detection system offers unique advantages of intrinsic safety, multi-location and multi-parameter monitoring. They can be potentially used to build expert systems for mine hazard early detection and prevention.

  4. Spider's web inspires fibres for industry

    NASA Astrophysics Data System (ADS)

    Dacey, James

    2010-03-01

    Spiders may not be everybody's idea of natural beauty, but nobody can deny the artistry in the webs that they spin, especially when decorated with water baubles in the morning dew. Inspired by this spectacle, a group of researchers in China has mimicked the structural properties of the spider's web to create a fibre for industry that can manipulate water with the same skill and efficiency, writes James Dacey.

  5. Electrophoretic analysis of proteins from single bovine muscle fibres.

    PubMed Central

    Young, O A; Davey, C L

    1981-01-01

    A number of single fibres were isolated by dissection of four bovine masseter (ma) muscles, three rectus abdominis (ra) muscles and eight sternomandibularis (sm) muscles. By histochemical criteria these muscles contain respectively, solely slow fibres (often called type I), predominantly fast fibres (type II), and a mixture of fast and slow. The fibres were analysed by conventional sodium dodecyl sulphate/polyacrylamide-gel electrophoresis and the gels stained with Coomassie Blue. Irrespective of the muscle, every fibre could be classed into one of two broad groups based on the mobility of proteins in the range 135000-170000 daltons. When zones containing myosin heavy chain were cut from the single-fibre gel tracks and 'mapped' [Cleveland, Fischer, Kirschner & Laemmli (1977) J. Biol. Chem. 252, 1102-1106] with Staphylococcus proteinase, it was found that one group always contained fast myosin heavy chain, whereas the second group always contained the slow form. Moreover, a relatively fast-migrating alpha-tropomyosin was associated with the fast myosin group and a slow-migrating form with the slow myosin group. All fibres also contained beta-tropomyosin; the coexistence of alpha- and beta-tropomyosin is at variance with evidence that alpha-tropomyosin is restricted to fast fibres [Dhoot & Perry (1979) Nature (London) 278, 714-718]. Fast fibres containing the expected fast light chains and troponins I and C fast were identified in the three ra muscles, but in only four sm muscles. In three other sm muscles, all the fast fibres contained two troponins I and an additional myosin light chain that was more typical of myosin light chain 1 slow. The remaining sm muscle contained a fast fibre type that was similar to the first type, except that its myosin light chain 1 was more typical of the slow polymorph. Troponin T was bimorphic in all fast fibres from a ra muscles and in at least some fast fibres from one sm muscle. Peptide 'mapping' revealed two forms of fast myosin

  6. Skinned fibres produce the same power and force as intact fibre bundles from muscle of wild rabbits.

    PubMed

    Curtin, Nancy A; Diack, Rebecca A; West, Timothy G; Wilson, Alan M; Woledge, Roger C

    2015-09-01

    Skinned fibres have advantages for comparing the muscle properties of different animal species because they can be prepared from a needle biopsy taken under field conditions. However, it is not clear how well the contractile properties of skinned fibres reflect the properties of the muscle fibres in vivo. Here, we compare the mechanical performance of intact fibre bundles and skinned fibres from muscle of the same animals. This is the first such direct comparison. Maximum power and isometric force were measured at 25 °C using peroneus longus (PL) and extensor digiti-V (ED-V) muscles from wild rabbits (Oryctolagus cuniculus). More than 90% of the fibres in these muscles are fast-twitch, type 2 fibres. Maximum power was measured in force-clamp experiments. We show that maximum power per volume was the same in intact (121.3 ± 16.1 W l(-1), mean ± s.e.m.; N=16) and skinned (122.6 ± 4.6 W l(-1); N=141) fibres. Maximum relative power (power/F(IM) Lo, where F(IM) is maximum isometric force and Lo is standard fibre length) was also similar in intact (0.645 ± 0.037; N=16) and skinned (0.589 ± 0.019; N=141) fibres. Relative power is independent of volume and thus not subject to errors in measurement of volume. Finally, maximum isometric force per cross-sectional area was also found to be the same for intact and skinned fibres (181.9 kPa ± 19.1; N=16; 207.8 kPa ± 4.8; N=141, respectively). These results contrast with previous measurements of performance at lower temperatures where skinned fibres produce much less power than intact fibres from both mammals and non-mammalian species. PMID:26206354

  7. Intrusive growth of primary and secondary phloem fibres in hemp stem determines fibre-bundle formation and structure.

    PubMed

    Snegireva, Anastasia; Chernova, Tatyana; Ageeva, Marina; Lev-Yadun, Simcha; Gorshkova, Tatyana

    2015-01-01

    Plant fibres-cells with important mechanical functions and a widely used raw material-are usually identified in microscopic sections only after reaching a significant length or after developing a thickened cell wall. We characterized the early developmental stages of hemp (Cannabis sativa) stem phloem fibres, both primary (originating from the procambium) and secondary (originating in the cambium), when they still had only a primary cell wall. We gave a major emphasis to the role of intrusive elongation, the specific type of plant cell growth by which fibres commonly attain large cell length. We could identify primary phloem fibres at a distance of only 1.2-1.5 mm from the shoot apical meristem when they grew symplastically with the surrounding tissues. Half a millimeter further downwards along the stem, fibres began their intrusive elongation, which led to a sharp increase in fibre numbers visible within the stem cross-sections. The intrusive elongation of primary phloem fibres was completed within the several distal centimetres of the growing stem, before the onset of their secondary cell wall formation. The formation of secondary phloem fibres started long after the beginning of secondary xylem formation. Our data indicate that only a small portion of the fusiform cambial initials (<10 %) give rise directly or via their derivatives to secondary phloem fibres. The key determinant of final bundle structure, both for primary and secondary phloem fibres, is intrusive growth. Through bi-directional elongation, fibres join other fibres initiated individually in other stem levels, thus forming the bundles. Our results provide the specific developmental basis for further biochemical and molecular-genetic studies of phloem fibre development in hemp, but may be applied to many other species. PMID:26019229

  8. Chronological ageing of human hair keratin fibres.

    PubMed

    Thibaut, S; de Becker, E; Bernard, B A; Huart, M; Fiat, F; Baghdadli, N; Luengo, G S; Leroy, F; Angevin, P; Kermoal, A M; Muller, S; Peron, M; Provot, G; Kravtchenko, S; Saint-Léger, D; Desbois, G; Gauchet, L; Nowbuth, K; Galliano, A; Kempf, J Y; Silberzan, I

    2010-12-01

    Examination of very long hair (length > 2.4 m) using a large range of evaluation methods including physical, chemical, biochemical and microscopic techniques has enabled to attain a detailed understanding of natural ageing of human hair keratin fibres. Scrutinizing hair that has undergone little or no oxidative aggression--because of the absence of action of chemical agents such as bleaching or dyeing--from the root to the tip shows the deterioration process, which gradually takes place from the outside to the inside of the hair shaft: first, a progressive abrasion of the cuticle, whilst the cortex structure remains unaltered, is evidenced along a length of roughly 1 m onwards together with constant shine, hydrophobicity and friction characteristics. Further along the fibre, a significant damage to cuticle scales occurs, which correlates well with ceramides and 18-Methyl Eicosanoic Acid (18-MEA) decline, and progressive decrease in keratin-associated protein content. Most physical descriptors of mechanical and optical properties decay significantly. This detailed description of natural ageing of human hair fibres by a fine analysis of hair components and physical parameters in relationship with cosmetic characteristics provides a time-dependent 'damage scale' of human hair, which may help in designing new targeted hair care formulations. PMID:20384898

  9. Towards woven logic from organic electronic fibres

    NASA Astrophysics Data System (ADS)

    Hamedi, Mahiar; Forchheimer, Robert; Inganäs, Olle

    2007-05-01

    The use of organic polymers for electronic functions is mainly motivated by the low-end applications, where low cost rather than advanced performance is a driving force. Materials and processing methods must allow for cheap production. Printing of electronics using inkjets or classical printing methods has considerable potential to deliver this. Another technology that has been around for millennia is weaving using fibres. Integration of electronic functions within fabrics, with production methods fully compatible with textiles, is therefore of current interest, to enhance performance and extend functions of textiles. Standard polymer field-effect transistors require well defined insulator thickness and high voltage, so they have limited suitability for electronic textiles. Here we report a novel approach through the construction of wire electrochemical transistor (WECT) devices, and show that textile monofilaments with 10-100μm diameters can be coated with continuous thin films of the conducting polythiophene poly(3,4-ethylenedioxythiophene), and used to create micro-scale WECTs on single fibres. We also demonstrate inverters and multiplexers for digital logic. This opens an avenue for three-dimensional polymer micro-electronics, where large-scale circuits can be designed and integrated directly into the three-dimensional structure of woven fibres.

  10. A Fibre Optic Sensor Of Physiological Parameters

    NASA Astrophysics Data System (ADS)

    Legendre, J. P.; Forester, G. V.

    1986-11-01

    This paper presents an ultraminiature fibre optic probe capable of physiological monitoring in situ. The system has been described previously where a fibre optic reflectometer was configured as a temperature sensor and as a refractometer. For the present experiments a bare fibre tip was used as sensing element. We show that we have been able to monitor cyclic physiological parameters such as heart and respiratory rates in various animal preparations. The probe has been used to obtain signals from the oesophagus, the lower gastro-intestinal tract, the abdominal cavity and from blood vessels (arteries and veins). The probe has also measured phasic activity coincident with mechanical activity of isolated heart muscle. The small physical size of the sensor (125 µm diameter), its flexibility and the fact that it is biologically inert are all very important characteristics for medical and biological considerations. Most recently, the probe has been used to monitor cardiac and respiratory rates while obtaining NMR spectra assessing metabolic activity. This was possible only because the probe is magnetically transparent.

  11. Novel ultrahigh resolution optical fibre temperature sensor

    NASA Astrophysics Data System (ADS)

    Poeggel, Sven; Duraibabu, Dineshbabu; Dooly, Gerard; Lewis, Elfed; Leen, Gabriel

    2016-05-01

    In this paper a novel patent pending high resolution optical fibre temperature sensor, based on an optical fibre pressure and temperature sensor (OFTPS), which is surrounded by an oil filled chamber, is presented. The OFPTS is based on a Fabry Perot interferometer (FPI) which has an embedded fibre Bragg grating (FBG). The high ratio between the volume of the oil filled outer cavity and the FPIs air filled cavity, results in a highly sensitive temperature sensor. The FBG element of the device can be used for wide range temperature measurements, and combining this capability with the high resolution capability of the FPI/oil cavity results in a wide range and high resolution temperature sensing device. The outer diameter of the sensor is less than 1mm in diameter and can be designed to be even smaller. The sensors temperature response was measured in a range of ΔT = 7K and resulted in a shift in the optical spectrum of ΔλF = 61.42nm. Therefore the Q-point of the reflected optical FPI spectrum is shifting with a sensitivity of sot = 8.77 nm/K . The sensitivity can easily be further increased by changing the oil/air volumetric ratio and therefore adapt the sensor to a wide variety of applications.

  12. Effects of chemical treatments on hemp fibre structure

    NASA Astrophysics Data System (ADS)

    Kabir, M. M.; Wang, H.; Lau, K. T.; Cardona, F.

    2013-07-01

    In this study, hemp fibres were treated with alkali, acetyl and silane chemicals. Fibre constituents such as cellulose, hemicellulose and lignin constituents were separated from treated fibres. The chemical and thermal influences of these constituents on the treated fibres were examined by using scanning electron microscope (SEM), fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Experimental results revealed that, hemicellulose was degraded faster than that of cellulose and lignin. Cellulose exhibited better thermal stability and lignin was degraded in a wide range of temperatures. The hydrophilic nature of the fibres was predominantly caused by the presence of hemicellulose and then lignin constituents. Hemicellulose and lignin were mostly removed by the alkalisation with higher concentrations of NaOH, followed by acetylation. Silane treatment could not remove the hemicellulose and lignin, rather this treatment facilitated coupling with the fibre constituents.

  13. Flat Ge-doped optical fibres for food irradiation dosimetry

    SciTech Connect

    Noor, N. Mohd; Jusoh, M. A.; Razis, A. F. Abdull; Alawiah, A.; Bradley, D. A.

    2015-04-24

    Exposing food to radiation can improve hygiene quality, germination control, retard sprouting, and enhance physical attributes of the food product. To provide for food safety, radiation dosimetry in irradiated food is required. Herein, fabricated germanium doped (Ge-doped) optical fibres have been used. The fibres have been irradiated using a gamma source irradiator, doses in the range 1 kGy to 10 kGy being delivered. Using Ge-doped optical fibres of variable size, type and dopant concentration, study has been made of linearity, reproducibility, and fading. The thermoluminescence (TL) yield of the fibres were obtained and compared. The fibres exhibit a linear dose response over the investigated range of doses, with mean reproducibility to within 2.69 % to 8.77 %, exceeding the dose range of all commercial dosimeters used in evaluating high doses for the food irradiation industry. TL fading of the Ge-doped flat fibres has been found to be < 13%.

  14. Flat Ge-doped optical fibres for food irradiation dosimetry

    NASA Astrophysics Data System (ADS)

    Noor, N. Mohd; Jusoh, M. A.; Razis, A. F. Abdull; Alawiah, A.; Bradley, D. A.

    2015-04-01

    Exposing food to radiation can improve hygiene quality, germination control, retard sprouting, and enhance physical attributes of the food product. To provide for food safety, radiation dosimetry in irradiated food is required. Herein, fabricated germanium doped (Ge-doped) optical fibres have been used. The fibres have been irradiated using a gamma source irradiator, doses in the range 1 kGy to 10 kGy being delivered. Using Ge-doped optical fibres of variable size, type and dopant concentration, study has been made of linearity, reproducibility, and fading. The thermoluminescence (TL) yield of the fibres were obtained and compared. The fibres exhibit a linear dose response over the investigated range of doses, with mean reproducibility to within 2.69 % to 8.77 %, exceeding the dose range of all commercial dosimeters used in evaluating high doses for the food irradiation industry. TL fading of the Ge-doped flat fibres has been found to be < 13%.

  15. Modelling the extrusion of preforms for microstructured optical fibres

    NASA Astrophysics Data System (ADS)

    Tronnolone, Hayden; Stokes, Yvonne; Crowdy, Darren

    2013-11-01

    Owing to a novel design, microstructured optical fibres (MOFs) promise the realisation of fibres with effectively any desired optical properties. MOFs are typically constructed from glass and employ a series of air channels aligned along the fibre axis to form a waveguide. The construction of MOFs by first extruding a preform and then drawing this into the final fibre has the potential to produce fibres on an industrial scale; however, this is hindered by a limited understanding of the fluid flow that arises during this process. We focus on the extrusion stage of fabrication and discuss a model of the fibre evolution based upon complex-variable techniques. The relative influence of the various physical processes involved is discussed, along with limitations of the model.

  16. Bismuth-doped Mg - Al silicate glasses and fibres

    SciTech Connect

    Bufetov, Igor' A; Vel'miskin, V V; Galagan, B I; Denker, B I; Sverchkov, S E; Semjonov, S L; Firstov, Sergei V; Shulman, I L; Dianov, Evgenii M

    2012-09-30

    This paper compares the optical properties of bulk bismuth-doped Mg - Al silicate glasses prepared in an iridium crucible to those of optical fibres prepared by the powder-in-tube method and having a core identical in composition to the glasses. The bulk glasses and fibres are shown to be similar in luminescence properties. The optical loss in the fibres in their IR luminescence band is about one order of magnitude lower than that in the crucible-melted glasses. The level of losses in the fibres and their luminescence properties suggest that such fibres can be made to lase near 1.15 {mu}m. (optical fibres, lasers and amplifiers. properties and applications)

  17. Guidance in Kagome-like photonic crystal fibres II: perturbation theory for a realistic fibre structure.

    PubMed

    Chen, Lei; Bird, David M

    2011-03-28

    A perturbation theory is developed that treats a localised mode embedded within a continuum of states. The method is applied to a model rectangular hollow-core photonic crystal fibre structure, where the basic modes are derived from an ideal, scalar model and the perturbation terms include vector effects and structural difference between the ideal and realistic structures. An expression for the attenuation of the fundamental mode due to interactions with cladding modes is derived, and results are presented for a rectangular photonic crystal fibre structure. Attenuations calculated in this way are in good agreement with numerical simulations. The origin of the guidance in our model structure is explained through this quantitative analysis. Further perspectives are obtained through investigating the influence of fibre parameters on the attenuation. PMID:21451721

  18. Effect of Steel Fibres Distribution on Impact Resistance Performance of Steel Fibre Reinforced Concrete (SFRC)

    NASA Astrophysics Data System (ADS)

    Che Muda, Zakaria; Liyana Mohd Kamal, Nur; Syamsir, Agusril; Shao Yang, Chen; Beddu, Salmia; Nasharuddin Mustapha, Kamal; Thiruchelvam, Sivadass; Usman, Fathoni; Itam, Zarina; Ashraful Alam, Md; Birima, Ahmed H.; Zaroog, O. S.

    2016-03-01

    This paper investigate the effect of the mesh distribution on the impact performance of steel fibre reinforced concrete (SFRC) for the concrete slab of 300mm × 300mm size reinforced with varied thickness and fraction volume subjected to low impact projectile test. A self-fabricated drop-weight impact test rig with a steel ball weight of 1.236 kg drop at 0.57 m height has been used in this research work. The objective of this research is to study the effect of the mesh distribution on the impact resistance SFRC for various slab thickness and fraction volume. Random fibre distribution is the more effective than the top and bottom fibre distribution in terms of absorption of impact energy, crack resistance, the ability to control crack formation and propagation against impact energy.

  19. Low frequency noise distributed-feedback ytterbium fibre laser

    SciTech Connect

    Nikulin, M A; Babin, S A; Kablukov, S I; Dmitriev, Aleksandr K; Dychkov, Aleksandr S; Lugovoy, Aleksei A; Pecherskii, Yu Ya

    2009-10-31

    We report a single-frequency 1-W fibre laser source emitting at 1093 nm, composed of a distributed-feedback ytterbium fibre laser and fibre-optic amplifier. The laser frequency was stabilised by side-locking to a transmission peak of a Fabry - Perot interferometer, and the residual frequency noise spectrum of the laser was measured. Our results indicate that the laser linewidth can be narrowed down below 1 kHz. (lasers)

  20. Rheology of Carbon Fibre Reinforced Cement-Based Mortar

    SciTech Connect

    Banfill, Phillip F. G.; Starrs, Gerry; McCarter, W. John

    2008-07-07

    Carbon fibre reinforced cement based materials (CFRCs) offer the possibility of fabricating 'smart' electrically conductive materials. Rheology of the fresh mix is crucial to satisfactory moulding and fresh CFRC conforms to the Bingham model with slight structural breakdown. Both yield stress and plastic viscosity increase with increasing fibre length and volume concentration. Using a modified Viskomat NT, the concentration dependence of CFRC rheology up to 1.5% fibre volume is reported.

  1. Rheology of Carbon Fibre Reinforced Cement-Based Mortar

    NASA Astrophysics Data System (ADS)

    Banfill, Phillip F. G.; Starrs, Gerry; McCarter, W. John

    2008-07-01

    Carbon fibre reinforced cement based materials (CFRCs) offer the possibility of fabricating "smart" electrically conductive materials. Rheology of the fresh mix is crucial to satisfactory moulding and fresh CFRC conforms to the Bingham model with slight structural breakdown. Both yield stress and plastic viscosity increase with increasing fibre length and volume concentration. Using a modified Viskomat NT, the concentration dependence of CFRC rheology up to 1.5% fibre volume is reported.

  2. The hygroscopic behavior of plant fibres: a review

    NASA Astrophysics Data System (ADS)

    Célino, Amandine; Freour, Sylvain; Jacquemin, Frederic; Casari, Pascal

    2013-12-01

    Environmental concern has resulted in a renewed interest in bio-based materials. Among them, plant fibres are perceived as an environmentally friendly substitute to glass fibres for the reinforcement of composites, particularly in automotive engineering. Due to their wide availability, low cost, low density, high-specific mechanical properties and eco-friendly image, they are increasingly being employed as reinforcements in polymer matrix composites. Indeed, their complex microstructure as a composite material makes plant fibre a really interesting and challenging subject to study. Research subjects about such fibres are abundant because there are always some issues to prevent their use at large scale (poor adhesion, variability, low thermal resistance, hydrophilic behavior). The choice of natural fibres rather than glass fibres as filler yields a change of the final properties of the composite. One of the most relevant differences between the two kinds of fibre is their response to humidity. Actually, glass fibres are considered as hydrophobic whereas plant fibres have a pronounced hydrophilic behavior. Composite materials are often submitted to variable climatic conditions during their lifetime, including unsteady hygroscopic conditions. However, in humid conditions, strong hydrophilic behaviour of such reinforcing fibres leads to high level of moisture absorption in wet environments. This results in the structural modification of the fibres and an evolution of their mechanical properties together with the composites in which they are fitted in. Thereby, the understanding of these moisture absorption mechanisms as well as the influence of water on the final properties of these fibres and their composites is of great interest to get a better control of such new biomaterials. This is the topic of this review paper.

  3. Lead silicate microstructured optical fibres for electro-optical applications.

    PubMed

    Zhang, Wen Qi; Manning, Sean; Ebendorff-Heidepriem, Heike; Monro, Tanya M

    2013-12-16

    We report progress towards the realization of optical modulators based on electro-optic effects in soft glass fibres. A hybrid fabrication procedure was developed for producing microstructured lead silicate glass fibres with internal electrodes. Electro-optical characterization confirms experimentally that the enhanced nonlinear properties and superior isolation between the optical field and the electrodes make these fibres an ideal candidate platform for efficient electro-optical devices. PMID:24514705

  4. Fibre Optic Temperature Sensors Using Fluorescent Phenomena.

    NASA Astrophysics Data System (ADS)

    Selli, Raman Kumar

    Available from UMI in association with The British Library. A number of fibre optic sensors based on fluorescent phenomena using low cost electronic and optical filtering techniques, for temperature sensing applications are described and discussed. The initial device developed uses the absorption edge change of an optical glass to monitor changes in temperature with a second wavelength reference channel being generated from a fluorescent material, neodymium doped in glass. This device demonstrates the working of the self-referencing principle in a practical device tested over the temperature range of -60^circ C to 200^circC. This initial device was improved by incorporating a microprocessor and by modifying the processing electronic circuitry. An alternative probe was constructed which used a second fibre placed along-side the addressing fibre in contrast to the original device where the fibre is placed at the opposite end of the addressing fibre. A device based on the same principle but with different absorption glasses and a different fluorescent medium, crystalline ruby, was also examined. This device operated at a lower wavelength region compared to the infra -red working region of the first device. This work illustrated the need to make an appropriate choice of sensor absorption glass so that the cheaper indicator type LEDs, which operated at lower wavelengths, may be used. Ruby is a fluorescent material which is characterized by each emission wavelength having its own temperature characteristics. The integrated energy output over the complete emission spectrum is independent of temperature. This provided a means of generating a reference from the complete spectrum while a small frequency band gave a temperature dependent output. This characteristic of ruby was used to develop a temperature measuring device. A final system which utilises the temperature dependent decay-time emission properties of crystalline ruby was developed. In this case the ruby was

  5. Guidance in Kagome-like photonic crystal fibres I: analysis of an ideal fibre structure.

    PubMed

    Chen, Lei; Pearce, Greg J; Birks, Timothy A; Bird, David M

    2011-03-28

    Propagation of light in a square-lattice hollow-core photonic crystal fibre is analysed as a model of guidance in a class of photonic crystal fibres that exhibit broad-band guidance without photonic bandgaps. A scalar governing equation is used and analytic solutions based on transfer matrices are developed for the full set of modes. It is found that an exponentially localised fundamental mode exists for a wide range of frequencies. These analytic solutions of an idealised structure will form the basis for analysis of guidance in a realistic structure in a following paper. PMID:21451720

  6. REVIEW ARTICLE: Modulational instability in a fibre and a fibre Bragg grating

    NASA Astrophysics Data System (ADS)

    Ganapathy, R.; Senthilnathan, K.; Porsezian, K.

    2004-05-01

    In this review article, we study the influence of cross-phase modulation, higher order nonlinear effects such as self-steepening, self-induced Raman scattering and higher order dispersion effects such as third and fourth order dispersion on cross-phase modulational instability for a highly elliptical birefringent optical fibre, and obtain the conditions for the occurrence of cross-phase modulational instability in the normal dispersion regime. In addition, we also consider the pulse propagation through a fibre Bragg grating structure where we investigate the occurrence of modulational instability at the two edges of the photonic bandgap as well as on the upper and lower branches of the dispersion curves.

  7. Photon irradiation response of photonic crystal fibres and flat fibres at radiation therapy doses.

    PubMed

    Hashim, S; Ibrahim, S A; Che Omar, S S; Alajerami, Y S M; Saripan, M I; Noor, N M; Ung, N M; Mahdiraji, G A; Bradley, D A; Alzimami, K

    2014-08-01

    Radiation effects of photon irradiation in pure Photonic Crystal Fibres (PCF) and Flat fibres (FF) are still much less investigated in thermoluminescense dosimetry (TLD). We have reported the TL response of PCF and FF subjected to 6 MV photon irradiation. The proposed dosimeter shows good linearity at doses ranging from 1 to 4 Gy. The small size of these detectors points to its use as a dosimeter at megavoltage energies, where better tissue-equivalence and the Bragg-Gray cavity theory prevails. PMID:24858954

  8. Electrostatic assembly and growth of gold nanoparticles in cellulosic fibres.

    PubMed

    Pinto, Ricardo J B; Marques, Paula A A P; Martins, Manuel A; Neto, Carlos Pascoal; Trindade, Tito

    2007-08-15

    Synthetic studies of nanocomposites containing gold nanoparticles attached onto wood or bacterial cellulosic fibres have been performed in situ in the presence of the fibres or by polyelectrolyte-assisted deposition. The optical properties of the final nanocomposites could be tailored not only by the starting Au nanoparticles characteristics but also by the preparative method associated to the type of cellulosic fibres used as the substrate. Thus, gold nanoparticles assembled or generated in situ within cellulosic fibres, are excellent components for long term optical and chemically stable nanocomposites, which appear particularly interesting for security paper applications. PMID:17459404

  9. Microstructured fibres: a positive impact on defence technology?

    NASA Astrophysics Data System (ADS)

    O'Driscoll, E. J.; Watson, M. A.; Delmonte, T.; Petrovich, M. N.; Feng, X.; Flanagan, J. C.; Hayes, J. R.; Richardson, D. J.

    2006-09-01

    In this paper we seek to assess the potential impact of microstructured fibres for security and defence applications. Recent literature has presented results on using microstructured fibre for delivery of high power, high quality radiation and also on the use of microstructured fibre for broadband source generation. Whilst these two applications may appear contradictory to one another the inherent design flexibility of microstructured fibres allows fibres to be fabricated for the specific application requirements, either minimising (for delivery) or maximising (for broadband source generation) the nonlinear effects. In platform based laser applications such as infrared counter measures, remote sensing and laser directed-energy weapons, a suitable delivery fibre providing high power, high quality light delivery would allow a laser to be sited remotely from the sensor/device head. This opens up the possibility of several sensor/device types sharing the same multi-functional laser, thus reducing the complexity and hence the cost of such systems. For applications requiring broadband source characteristics, microstructured fibres can also offer advantages over conventional sources. By exploiting the nonlinear effects it is possible to realise a multifunctional source for applications such as active hyperspectral imaging, countermeasures, and biochemical sensing. These recent results suggest enormous potential for these novel fibre types to influence the next generation of photonic systems for security and defence applications. However, it is important to establish where the fibres can offer the greatest advantages and what research still needs to be done to drive the technology towards real platform solutions.

  10. Ultrafast fibre laser sources: Examples of recent developments

    NASA Astrophysics Data System (ADS)

    Zhang, M.; Kelleher, E. J. R.; Popov, S. V.; Taylor, J. R.

    2014-12-01

    We summarise a number of recent experimental developments in the field of ultrafast compact all-fibre lasers, including: ionically-doped coloured glass saturable absorbers; Tm:fibre lasers utilising graphene around 2 μ m; alternative layered materials including MoS2; passively synchronised, coupled-cavity ultrafast dual-wavelength fibre lasers; and schemes for the generation of high repetition rate femtosecond pulses based on phase modulation, and spectral masking of CW radiation. The breadth of light sources covered in this review highlights the diversity of approaches in ongoing research in the field of ultrafast fibre optics.

  11. Multiwalled carbon nanotube reinforced biomimetic bundled gel fibres.

    PubMed

    Kim, Young-Jin; Yamamoto, Seiichiro; Takahashi, Haruko; Sasaki, Naruo; Matsunaga, Yukiko T

    2016-08-19

    This work describes the fabrication and characterization of hydroxypropyl cellulose (HPC)-based biomimetic bundled gel fibres. The bundled gel fibres were reinforced with multiwalled carbon nanotubes (MWCNTs). A phase-separated aqueous solution with MWCNT and HPC was transformed into a bundled fibrous structure after being injected into a co-flow microfluidic device and applying the sheath flow. The resulting MWCNT-bundled gel fibres consist of multiple parallel microfibres. The mechanical and electrical properties of MWCNT-bundled gel fibres were improved and their potential for tissue engineering applications as a cell scaffold was demonstrated. PMID:27200527

  12. The Applications Of Fibre Optics In Gas Turbine Engine Instrumentation

    NASA Astrophysics Data System (ADS)

    Davinson, Ian

    1984-08-01

    Instrumentation in Gas Turbines must operate in extremely harsh environments. Electro-optical methods are being increasingly used to measure such variables as displacement, temperature and gas flow and fibre optics are often required to enable sensitive electronic components to be placed remote from the hostile region. This paper reviews applications of fibre optics in Rolls-Royce up to the present. In addition the case for using fibre optic sensors for the measurement of other parameters in future will be presented, along with a discussion of the prospects for fibre optic data transmission on the next generation of digitally controlled engines.

  13. Dynamic behaviour of HPFRCC: The influence of fibres dispersion

    NASA Astrophysics Data System (ADS)

    Caverzan, Alessio; di Prisco, Marco; Cadoni, Ezio

    2015-09-01

    The promise of fibre-reinforced cementitious composites for dynamic loading application stems from their observed good response under static loading mainly due to fibre contribution. An experimental research aimed at contributing to the understanding of the behaviour of advanced fibre-reinforced cementitious composites subjected to low and high strain rates was carried out underlining the influence of fibres. The material behaviour was investigated at three strain rates (0.1, 1, and 150 s-1) and the tests results were compared with their static behaviour. Tests at intermediate strain rates (0.1-1 s-1) were carried out by means of a hydro-pneumatic machine (HPM), while high strain rates (150 s-1) were investigated by exploiting a modified Hopkinson bar (MHB). Particular attention has been placed on the influence of fibre and fibre dispersion on the dynamic behaviour of the materials: matrix, HPFRCC with random fibre distribution and aligned fibres were compared. The comparison between static and dynamic tests highlighted several relevant aspects regarding the influence of fibres on the peak strength and post-peak behaviour at high strain rates.

  14. Spider silk: a novel optical fibre for biochemical sensing

    NASA Astrophysics Data System (ADS)

    Hey Tow, Kenny; Chow, Desmond M.; Vollrath, Fritz; Dicaire, Isabelle; Gheysens, Tom; Thévenaz, Luc

    2015-09-01

    Whilst being thoroughly used in the textile industry and biomedical sector, silk has not yet been exploited for fibre optics-based sensing although silk fibres directly obtained from spiders can guide light and have shown early promises to being sensitive to some solvents. In this communication, a pioneering optical fibre sensor based on spider silk is reported, demonstrating for the first time the use of spider silk as an optical fibre sensor to detect polar solvents such as water, ammonia and acetic acid.

  15. New optical fibres for high-capacity optical communications

    PubMed Central

    Richardson, D. J.

    2016-01-01

    Researchers are within a factor of 2 or so from realizing the maximum practical transmission capacity of conventional single-mode fibre transmission technology. It is therefore timely to consider new technological approaches offering the potential for more cost-effective scaling of network capacity than simply installing more and more conventional single-mode systems in parallel. In this paper, I review physical layer options that can be considered to address this requirement including the potential for reduction in both fibre loss and nonlinearity for single-mode fibres, the development of ultra-broadband fibre amplifiers and finally the use of space division multiplexing. PMID:26809569

  16. The projections of chemically identified nerve fibres in canine ileum.

    PubMed

    Daniel, E E; Furness, J B; Costa, M; Belbeck, L

    1987-02-01

    The projections of nerve fibres with immunoreactivity for the peptides enkephalin (ENK), gastrin-releasing peptide (GRP), neuropeptide Y (NPY), somatostatin (SOM), substance P (SP) and vasoactive intestinal peptide (VIP) were studied in canine small intestine by analysing the consequences of lesions of intrinsic and extrinsic nerves. Of peptides present in fibres supplying myenteric ganglia, GRP, SOM and VIP were in anally directed nerve pathways, whereas ENK and NPY were in orally directed pathways. Pathways ran for up to about 30 mm. SP fibres ran for short distances in both directions in the myenteric plexus. The circular muscle was supplied with ENK, NPY, SP and VIP fibres arising from the myenteric ganglia, whereas most mucosal SP and VIP fibres were deduced to arise from submucous ganglia. There were projections of fibres reactive for ENK, GRP, SOM, SP and VIP from myenteric ganglia to submucous ganglia. Antibodies to tyrosine hydroxylase were used to locate noradrenaline nerve fibres supplying the intestine; these fibres all disappeared when extrinsic nerves running through the mesentery to the small intestine were cut. It is deduced that there is an ordered pattern of projections of peptide-containing fibres in the canine intestine. PMID:2434235

  17. Nonlinear Optics and Solitons in Photonic Crystal Fibres

    NASA Astrophysics Data System (ADS)

    Skryabin, Dmitry V.; Wadsworth, William J.

    The fibre optics revolution in communication technologies followed the 1950's demonstration of the glass fibres with dielectric cladding [1]. Transmission applications of fibre optics have become a dominant modern day technology not least because nonlinearities present in - or introduced into - glass and enhanced by the tight focusing of the fibre modes allow for numerous light processing techniques, such as amplification, frequency conversion, pulse shaping, and many others. For these reasons, and because of the rich fundamental physics behind it, nonlinear fibre optics has become a blossoming discipline in its own right [1]. The 1990's witnessed another important development in fibre optics. Once again it came from a new approach to the fibre cladding, comprising a periodic pattern of air holes separated by glass membranes forming a photonic crystal structure [2, 3]. This prompted the name Photonic Crystal Fibres (PCFs). The fascinating story behind the invention of PCF and research into various fibre designs can be found, e.g., in [4]. Our aim here is to review the role played by PCFs in nonlinear and quantum optics, which is becoming the mainstream of the PCF related research and applications. Our focus will be on the areas where PCFs have brought to life effects and applications which were previously difficult, impossible to observe or simply not thought about.

  18. New optical fibres for high-capacity optical communications.

    PubMed

    Richardson, D J

    2016-03-01

    Researchers are within a factor of 2 or so from realizing the maximum practical transmission capacity of conventional single-mode fibre transmission technology. It is therefore timely to consider new technological approaches offering the potential for more cost-effective scaling of network capacity than simply installing more and more conventional single-mode systems in parallel. In this paper, I review physical layer options that can be considered to address this requirement including the potential for reduction in both fibre loss and nonlinearity for single-mode fibres, the development of ultra-broadband fibre amplifiers and finally the use of space division multiplexing. PMID:26809569

  19. Synthesis and densification of lutetium pyrosilicate from lutetia and silica

    SciTech Connect

    Tripathi, Himansu S.; Sarin, Vinod K. . E-mail: sarin@bu.edu

    2007-02-15

    Cerium-doped lutetium pyrosilicate (Lu{sub 2}Si{sub 2}O{sub 7}:Ce) powder was synthesized by solid state reaction of Lu{sub 2}O{sub 3} and SiO{sub 2}. Stoichiometric mixtures of the starting materials were heat treated at various different temperatures and their phase contents were measured by XRD technique. It was found that the first step in the formation of Lu{sub 2}Si{sub 2}O{sub 7} (LPS) is the appearance of Lu{sub 2}SiO{sub 5} (LSO). This takes place at 1100 deg. C, fully 300 deg. C below the first appearance of LPS. Between 1400 and 1500 deg. C both LSO and LPS coexist in the calcined batch, but by 1550 deg. C all LSO is completely converted to LPS. LPS formation temperature does not have appreciable effect on the density of the hot pressed samples. Hot pressed samples obtained from powder synthesized at 1650 deg. C are nearly transparent, although the particle size of the starting powder is higher than that of the powder formed at lower temperatures.

  20. Simulation of Peptide Binding to Silica and Silica Mineralization

    NASA Astrophysics Data System (ADS)

    Emami, F. S.; Heinz, H.; Berry, R. J.; Varshney, V.; Farmer, B. L.; Naik, R. R.; Patwardhan, S. V.; Perry, C. C.

    2009-03-01

    The purpose of this study is to identify the nature of the interaction of peptides with silica surfaces and their effect on mineralization. Classical force fields (CVFF, PCFF) have been extended for silica aiming at the computation of surface properties in quantitative agreement with experiment, taking explicitly into account water molecules, pH, and surface coverage with peptides. We focus on the interaction of five short peptides (pep1, pep4, 82-4, H4, R5) identified by biopanning with regular and amorphous silica surfaces (Q3 and Q2) to understand the relation between peptide sequence and affinity to the surface. Results of the atomistic molecular dynamics simulation indicate adsorption energies, binding constants and conformational changes upon adsorption. The comparison of NMR chemical shifts in solution and on the surface in computation and experiment further aids in understanding the mechanism of binding.

  1. Specimen specific parameter identification of ovine lumbar intervertebral discs: On the influence of fibre-matrix and fibre-fibre shear interactions.

    PubMed

    Reutlinger, Christoph; Bürki, Alexander; Brandejsky, Vaclav; Ebert, Lars; Büchler, Philippe

    2014-02-01

    Numerical models of the intervertebral disc, which address mechanical questions commonly make use of the difference in water content between annulus and nucleus, and thus fluid and solid parts are separated. Despite this simplification, models remain complex due to the anisotropy and nonlinearity of the annulus and regional variations of the collagen fibre density. Additionally, it has been shown that cross-links make a large contribution to the stiffness of the annulus. Because of this complex composite structure, it is difficult to reproduce several sets of experimental data with one single set of material parameters. This study addresses the question to which extent the ultrastructure of the intervertebral disc should be modelled so that its moment-angle behaviour can be adequately described. Therefore, a hyperelastic constitutive law, based on continuum mechanical principles was derived, which does not only consider the anisotropy from the collagen fibres, but also interactions among the fibres and between the fibres and the ground substance. Eight ovine lumbar intervertebral discs were tested on a custom made spinal loading simulator in flexion/extension, lateral bending and axial rotation. Specimen-specific geometrical models were generated using CT images and T2 maps to distinguish between annulus fibrosus and nucleus pulposus. For the identification of the material parameters the annulus fibrosus was described with two scenarios: with and without fibre-matrix and fibre-fibre interactions. Both scenarios showed a similar behaviour on a load displacement level. Comparing model predictions to the experimental data, the mean RMS of all specimens and all load cases was 0.54±0.15° without the interaction and 0.54±0.19° when the fibre-matrix and fibre-fibre interactions were included. However, due to the increased stiffness when cross-links effects were included, this scenario showed more physiological stress-strain relations in uniaxial and biaxial stress

  2. Surface modification of silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Ranjan, Rajesh

    Surface modification of nanosized silica particles by polymer grafting is gaining attention. This can be attributed to the fact that it provides a unique opportunity to engineer the interfacial properties of these modified particles; at the same time the mechanical and thermal properties of the polymers can be improved. Controlled free radical polymerization is a versatile technique which affords control over molecular weight, molecular weight distribution, architecture and functionalities of the resulting polymer. Three commonly used controlled free radical polymerizations include nitroxide-mediated polymerization (NMP), atom transfer radical polymerization (ATRP) and reversible addition fragmentation transfer (RAFT) polymerization. ATRP and RAFT polymerization were explored in order to modify the silica surface with well-defined polymer brushes. A novel click-functionalized RAFT chain transfer agent (RAFT CTA) was synthesized which opened up the possibility of using RAFT polymerization and click chemistry together in surface modification. Using this RAFT CTA, the surface of silica nanoparticles was modified with polystyrene and polyacrylamide brushes via the "grafting to" approach. Both tethered polystyrene and polyacrylamide chains were found in the brush regime. The combination of ATRP and click chemistry was also explored for surface modification. A combination of RAFT polymerization and click chemistry was also studied to modify the surface via the "grafting from" approach. Our strategy included the (1) "grafting from" approach for brush formation (2) facile click reaction to immobilize the RAFT agent (3) synthesis of R-supported chain transfer agent and (4) use of the more active trithiocarbonate RAFT agent. Grafting density obtained by this method was significantly higher than reported values in the literature. Polystyrene (PS) grafted silica nanoparticles were also prepared by a tandem process that simultaneously employs reversible addition fragmentation

  3. Intrusive growth of primary and secondary phloem fibres in hemp stem determines fibre-bundle formation and structure

    PubMed Central

    Snegireva, Anastasia; Chernova, Tatyana; Ageeva, Marina; Lev-Yadun, Simcha; Gorshkova, Tatyana

    2015-01-01

    Plant fibres—cells with important mechanical functions and a widely used raw material—are usually identified in microscopic sections only after reaching a significant length or after developing a thickened cell wall. We characterized the early developmental stages of hemp (Cannabis sativa) stem phloem fibres, both primary (originating from the procambium) and secondary (originating in the cambium), when they still had only a primary cell wall. We gave a major emphasis to the role of intrusive elongation, the specific type of plant cell growth by which fibres commonly attain large cell length. We could identify primary phloem fibres at a distance of only 1.2–1.5 mm from the shoot apical meristem when they grew symplastically with the surrounding tissues. Half a millimeter further downwards along the stem, fibres began their intrusive elongation, which led to a sharp increase in fibre numbers visible within the stem cross-sections. The intrusive elongation of primary phloem fibres was completed within the several distal centimetres of the growing stem, before the onset of their secondary cell wall formation. The formation of secondary phloem fibres started long after the beginning of secondary xylem formation. Our data indicate that only a small portion of the fusiform cambial initials (<10 %) give rise directly or via their derivatives to secondary phloem fibres. The key determinant of final bundle structure, both for primary and secondary phloem fibres, is intrusive growth. Through bi-directional elongation, fibres join other fibres initiated individually in other stem levels, thus forming the bundles. Our results provide the specific developmental basis for further biochemical and molecular-genetic studies of phloem fibre development in hemp, but may be applied to many other species. PMID:26019229

  4. Precipitated silica as flow regulator.

    PubMed

    Müller, Anne-Kathrin; Ruppel, Joanna; Drexel, Claus-Peter; Zimmermann, Ingfried

    2008-08-01

    Flow regulators are added to solid pharmaceutical formulations to improve the flow properties of the powder mixtures. The primary particles of the flow regulators exist in the form of huge agglomerates which are broken down into smaller aggregates during the blending process. These smaller aggregates adsorb at the surface of the solid's grains and thus diminish attractive Van-der-Waals-forces by increasing the roughness of the host's surface. In most cases amorphous silica is used as flow additive but material properties like particle size or bond strength influence the desagglomeration tendency of the agglomerates and thus the flow regulating potency of each silica. For some silica types we will show that the differences in their flow regulating potency are due to the rate and extent by which they are able to cover the surface of the host particles. Binary powder mixtures consisting of a pharmaceutical excipient and an added flow regulator were blended in a Turbula mixer for a defined period of time. As pharmaceutical excipient corn starch was used. The flow regulators were represented by a selection of amorphous silicon dioxide types like a commercial fumed silica and various types of SIPERNAT precipitated silica provided by Evonik-Degussa GmbH, Hanau, Germany. Flowability parameters of the mixtures were characterized by means of a tensile strength tester. The reduction of tensile strength with the blending time can be correlated with an increase in fragmentation of the flow regulator. PMID:18595668

  5. Exposure to crystalline silica in abrasive blasting operations where silica and non-silica abrasives are used.

    PubMed

    Radnoff, Diane L; Kutz, Michelle K

    2014-01-01

    Exposure to respirable crystalline silica is a hazard common to many industries in Alberta but particularly so in abrasive blasting. Alberta occupational health and safety legislation requires the consideration of silica substitutes when conducting abrasive blasting, where reasonably practicable. In this study, exposure to crystalline silica during abrasive blasting was evaluated when both silica and non-silica products were used. The crystalline silica content of non-silica abrasives was also measured. The facilities evaluated were preparing metal products for the application of coatings, so the substrate should not have had a significant contribution to worker exposure to crystalline silica. The occupational sampling results indicate that two-thirds of the workers assessed were potentially over-exposed to respirable crystalline silica. About one-third of the measurements over the exposure limit were at the work sites using silica substitutes at the time of the assessment. The use of the silica substitute, by itself, did not appear to have a large effect on the mean airborne exposure levels. There are a number of factors that may contribute to over-exposures, including the isolation of the blasting area, housekeeping, and inappropriate use of respiratory protective equipment. However, the non-silica abrasives themselves also contain silica. Bulk analysis results for non-silica abrasives commercially available in Alberta indicate that many contain crystalline silica above the legislated disclosure limit of 0.1% weight of silica per weight of product (w/w) and this information may not be accurately disclosed on the material safety data sheet for the product. The employer may still have to evaluate the potential for exposure to crystalline silica at their work site, even when silica substitutes are used. Limited tests on recycled non-silica abrasive indicated that the silica content had increased. Further study is required to evaluate the impact of product recycling

  6. Variability of muscle fibre composition and fibre size in the horse gluteus medius: an enzyme-histochemical and morphometric study.

    PubMed Central

    López-Rivero, J L; Serrano, A L; Diz, A M; Galisteo, A M

    1992-01-01

    To determine the variability in fibre types and fibre sizes in the equine gluteus medius muscle, biopsy specimens were removed from 5 sites, at 4 different depths, within the right and left muscles of 3 Andalusian stallions. The percentage, lesser fibre diameter and cross-sectional area of the various fibre types were measured systematically in myosin ATPase and NADH-tetrazolium reductase-stained, serial cryostat sections of these multiple samples. Significant differences in muscle fibre type composition were recorded, with a lower percentage of type I fibres (high myosin ATPase activity at pH 4.5) being observed towards superficial regions of the muscle and a greater percentage towards the deep areas. Type II B fibres (moderate myosin ATPase activity at pH 4.5), including both II B nonoxidative (low NADH-TR activity) and II B oxidative (moderate NADH-TR activity), displayed the opposite tendency, and the percentage of type II A fibres (low myosin ATPase activity at pH 4.5) did not change with depth. Types I and II A fibres in the deep regions were larger than superficially, whereas the II B fibres in the deep regions were smaller than in the superficial parts of the muscle. The results also imply that type I fibres tend to be larger than type II fibres in the deep regions. The size of type I fibres is more homogeneous in the deep parts than in the superficial regions of the muscle, while II B fibres vary more in size in the peripheral portions than in deep regions. A single biopsy taken from the gluteus medius muscle of the horse is therefore a poor representative of the whole muscle and care should be exercised in sampling and interpreting data obtained from limited biopsy of this muscle. The pattern of variation in fibre types and fibre sizes between the different depths of the muscle probably reflect different functional demands on the gluteus medius muscle. Images Fig. 1 PMID:1284127

  7. Admicellar polymerization of precipated silica

    SciTech Connect

    Reynolds, J.L.; Grady, B.P.; Harwell, J.H.

    1996-10-01

    The tendency of a surfactant molecule to adsorb at a solid-liquid interface is the basis for an in situ surface modification process, termed admicellar polymerization. The four-step admicellar polymerization process includes: (1) adsorption of surfactant at the solid-liquid interface, (2) adsolubilization of monomer into the surfactant bilayer, (3) polymerization using free-radical initiators and heat, (4) removal of excess surfactant to expose the polymer modified surface. The process is used to apply polymer to precipitated silica to enhance the compatibility of the silica when added to filled rubber. The adsorption isotherms were first determined for particular surfactant/silica combinations to find the surfactant concentration that would sufficiently adsolubilize the monomer, while remaining below the critical micelle concentration. A series of experiments were then devised for the polymerization reactions in which the surfactant and monomer amounts were varied over three levels to establish the optimal combination.

  8. Torsional moment to failure for carbon fibre polysulphone expandable rivets as compared with stainless steel screws for carbon fibre-reinforced epoxy fracture plate fixation.

    PubMed

    Sell, P J; Prakash, R; Hastings, G W

    1989-04-01

    A method of securing carbon fibre-reinforced epoxy bone plates with carbon fibre polysulphone expanding rivets was investigated. Six carbon fibre-reinforced epoxy bone plates were secured to rods with carbon fibre polysulphone rivets and six were secured with standard cortical stainless steel screws. These constructions were then subjected to pure torsional load to failure. The carbon fibre expandable rivets failed at a greater torsional moment. PMID:2720038

  9. Beads, beaded-fibres and fibres: Tailoring the morphology of poly(caprolactone) using pressurised gyration.

    PubMed

    Hong, Xianze; Edirisinghe, Mohan; Mahalingam, Suntharavathanan

    2016-12-01

    This work focuses on forming bead on string poly(caprolactone) (PCL) by using gyration under pressure. The fibre morphology of bead on string is an interesting feature that falls between bead-free fibres and droplets, and it could be effectively controlled by the rheological properties of spinning dopes and the major processing parameters of the pressurised gyration system which are working pressure and rotating speed. Bead products were not always spherical in shape and tended to be more elliptical, therefore both their width and length were measured. The average bead width and length produced spanned a range 145-660μm and 140-1060μm, respectively. The average distance between two adjacent beads (i.e. inter-bead distance) and the bead size (width and length) are shown to be a function of processing parameters and polymer concentration. An interesting morphology i.e. beads with short fibre was observed when using a high polymer concentration. Bead on string structure agglomeration was promoted by a low polymer concentration. Formation of droplets or agglomerated bead on string is promoted below 5wt% polymer concentration, and beads with short fibre were present in the microstructure beyond a polymer concentration of 20wt%. PMID:27612839

  10. 21 CFR 584.700 - Hydrophobic silicas.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...: (i) Amorphous fumed hydrophobic silica: Not less than 99.0 percent silicon dioxide after ignition... dichlorodimethylsilane. (ii) Precipated hydrophobic silica: Not less than 94.0 percent silicon dioxide after...

  11. Physisorbed Water on Silica at Mars Temperatures

    NASA Technical Reports Server (NTRS)

    Sutter, B.; Sriwatanapongse, W.; Quinn, R.; Klug, C.; Zent, A.

    2002-01-01

    The usefulness of nuclear magnetic resonance spectroscopy in probing water interactions on silica at Mars temperatures is discussed. Results indicate that two types of water occur with silica at Mars temperatures. Additional information is contained in the original extended abstract.

  12. Optothermal nonlinearity of silica aerogel

    NASA Astrophysics Data System (ADS)

    Braidotti, Maria Chiara; Gentilini, Silvia; Fleming, Adam; Samuels, Michiel C.; Di Falco, Andrea; Conti, Claudio

    2016-07-01

    We report on the characterization of silica aerogel thermal optical nonlinearity, obtained by z-scan technique. The results show that typical silica aerogels have nonlinear optical coefficient similar to that of glass (≃10-12 m2/W), with negligible optical nonlinear absorption. The nonlinear coefficient can be increased to values in the range of 10-10 m2/W by embedding an absorbing dye in the aerogel. This value is one order of magnitude higher than that observed in the pure dye and in typical highly nonlinear materials like liquid crystals.

  13. Silica Precursors Derived From TEOS

    NASA Technical Reports Server (NTRS)

    Philipp, Warren H.

    1993-01-01

    Two high-char-yield polysiloxane polymers developed. Designated as TEOS-A and TEOS-B with silica char yields of 55% and 22%, respectively. These free-flowing polymers are Newtonium liquids instead of thick gels. Easily synthesized by controlled hydrolysis of inexpensive tetraethoxysilane (TEOS). Adhesive properties of TEOS-A suggest its use as binder for fabrication of ceramic articles from oxide powders. Less-viscous and more-fluid lower-molecular-weight TEOS-B used to infiltrate already-formed porous ceramic compacts to increase densities without effecting shrinkage. Also used as paint to coat substrate with silica, and to make highly pure silicate powders.

  14. Removal of dissolved and colloidal silica

    DOEpatents

    Midkiff, William S.

    2002-01-01

    Small amorphous silica particles are used to provide a relatively large surface area upon which silica will preferentially adsorb, thereby preventing or substantially reducing scaling caused by deposition of silica on evaporative cooling tower components, especially heat exchange surfaces. The silica spheres are contacted by the cooling tower water in a sidestream reactor, then separated using gravity separation, microfiltration, vacuum filtration, or other suitable separation technology. Cooling tower modifications for implementing the invention process have been designed.

  15. The properties of silica-gelatin composites

    NASA Astrophysics Data System (ADS)

    Stavinskaya, O. N.; Laguta, I. V.

    2010-06-01

    Silica-gelatin composites with various silica-to-gelatin ratios were obtained. The influence of high-dispersity silica on the swelling of composites in water and desorption of pyridoxine and thiamine vitamins incorporated into the material was studied. The addition of silica to gelatin was shown to increase the time of the dissolution of the materials in aqueous medium and decelerate the desorption of vitamins.

  16. Tunable fibre-coupled multiphoton microscopy with a negative curvature fibre.

    PubMed

    Sherlock, Ben; Yu, Fei; Stone, Jim; Warren, Sean; Paterson, Carl; Neil, Mark A A; French, Paul M W; Knight, Jonathan; Dunsby, Chris

    2016-07-01

    Negative curvature fibre (NCF) guides light in its core by inhibiting the coupling of core and cladding modes. In this work, an NCF was designed and fabricated to transmit ultrashort optical pulses for multiphoton microscopy with low group velocity dispersion (GVD) at 800 nm. Its attenuation was measured to be <0.3 dB m(-1) over the range 600-850 nm and the GVD was -180 ± 70 fs(2)  m(-1) at 800 nm. Using an average fibre output power of ∼20 mW and pulse repetition rate of 80 MHz, the NCF enabled pulses with a duration of <200 fs to be transmitted through a length of 1.5 m of fibre over a tuning range of 180 nm without the need for dispersion compensation. In a 4 m fibre, temporal and spectral pulse widths were maintained to within 10% of low power values up to the maximum fibre output power achievable with the laser system used of 278 mW at 700 nm, 808 mW at 800 nm and 420 mW at 860 nm. When coupled to a multiphoton microscope, it enabled imaging of ex vivo tissue using excitation wavelengths from 740 nm to 860 nm without any need for adjustments to the set-up. PMID:26989868

  17. REVIEW ARTICLE Blue extension of optical fibre supercontinuum generation

    NASA Astrophysics Data System (ADS)

    Travers, J. C.

    2010-11-01

    Supercontinuum generation in optical fibres pumped with high power pulse sources in the modulation instability regime is reviewed. The physical mechanisms and supercontinuum dynamics are described in detail. Routes to optimized output in terms of spectral flatness and particularly blue and ultraviolet spectral extent are presented, including the use of cascaded and tapered photonic crystal fibres.

  18. Semiconductor disk laser-pumped subpicosecond holmium fibre laser

    SciTech Connect

    Chamorovskiy, A Yu; Marakulin, A V; Leinonen, T; Kurkov, Andrei S; Okhotnikov, Oleg G

    2012-01-31

    The first passively mode-locked holmium fibre laser has been demonstrated, with a semiconductor saturable absorber mirror (SESAM) as a mode locker. Semiconductor disk lasers have been used for the first time to pump holmium fibre lasers. We obtained 830-fs pulses at a repetition rate of 34 MHz with an average output power of 6.6 mW.

  19. Different types of extrafusal muscle fibres in snake costocutaneous muscles

    PubMed Central

    Ridge, R. M. A. P.

    1971-01-01

    1. Tonic and twitch muscle fibres were identified physiologically in m. costocutanei superiores and inferiores of garter snakes and grass snakes. 2. Tonic fibres were multiterminally innervated and showed s.j.p.s in response to nerve stimulation. They did not show propagated A.P.s. They were innervated by motor axons with lower conduction velocities than those to twitch fibres, and often gave a contraction and developed tension in response to a single shock to the nerve. Intracellular square pulse analysis showed that Cm = 1 μF/cm2 and Rm = 40,000 Ω cm2. 3. Twitch fibres showed a conducted action potential in response to nerve stimulation, and focal, as opposed to diffuse, innervation. They showed a variety of isometric twitch contraction times (times-to-peak of about 30-65 msec). Groups of similar motor units contained fibres of approximately similar contraction times. Slow twitch (and tonic) fibres often appeared silvery under dark field illumination, while faster twitch fibres appeared clear. No difference in Cm, Rm or λ was found between faster and slow twitch fibres. Values were approximately 3-4 μF/cm2, 3000-4000 Ω cm2 and 2 mm respectively. ImagesFig. 6 PMID:5097606

  20. Filter media properties of mineral fibres produced by plasma spray.

    PubMed

    Prasauskas, Tadas; Matulevicius, Jonas; Kliucininkas, Linas; Krugly, Edvinas; Valincius, Vitas; Martuzevicius, Dainius

    2016-06-01

    The purpose of this study was to determine the properties of fibrous gas filtration media produced from mineral zeolite. Fibres were generated by direct current plasma spray. The paper characterizes morphology, chemical composition, geometrical structure of elementary fibres, and thermal resistance, as well as the filtration properties of fibre media. The diameter of the produced elementary fibres ranged from 0.17 to 0.90 μm and the length ranged from 0.025 to 5.1 mm. The release of fibres from the media in the air stream was noticed, but it was minimized by hot-pressing the formed fibre mats. The fibres kept their properties up to the temperature of 956°C, while further increase in temperature resulted in the filter media becoming shrunk and brittle. The filtration efficiency of the prepared filter mats ranged from 95.34% to 99.99% for aerosol particles ranging in a size between 0.03 and 10.0 μm. Unprocessed fibre media showed the highest filtration efficiency when filtering aerosol particles smaller than 0.1 µm. Hot-pressed filters were characterized by the highest quality factor values, ranging from 0.021 to 0.064 Pa(-1) (average value 0.034 Pa(-1)). PMID:26583905

  1. Ultrastructural observation of single-crystal apatite fibres.

    PubMed

    Aizawa, Mamoru; Porter, Alexandra E; Best, Serena M; Bonfield, William

    2005-06-01

    Hydroxyapatite (HAp) has been widely used as a biomaterial for substituting human hard tissues such as bone. By altering the morphology of HAp crystals, novel properties may be produced by controlling the orientation of the crystal planes. Apatite fibres were successfully synthesized by precipitation from aqueous solutions containing Ca(NO(3))(2), (NH(4))(2)HPO(4), urea and HNO(3). The products were composed of carbonate-containing apatite fibres with preferred orientation along the {h00} planes. Examination of individual fibres using transmission electron microscopy showed that the as-synthesized apatite fibres were highly strained single crystals with the c-axis orientation parallel to the long axis of the fibre. The crushed fibres consisted of domains that were preferentially oriented with the c-axis parallel to the long axis of the fibres. When the apatite fibres were heated to 800, 1000 and 1200 degrees C for 1h, the domains were removed and grain boundaries, dislocations and voids were formed. PMID:15621231

  2. Comparison of silica-core optical fibers

    NASA Astrophysics Data System (ADS)

    McCann, Brian P.

    1991-07-01

    Silica-core optical fibers have become a standard vehicle to remotely deliver high-power laser energy from surgical lasers operating between 200 and 2400 nm. The three primary types of silica-core fibers: plastic-clad; hard-clad; and silica-clad; are discussed. The performance advantages of each are addressed and actual general-surgery medical applications are provided.

  3. Automated segmentation of wood fibres in micro-CT images of paper.

    PubMed

    Sharma, Y; Phillion, A B; Martinez, D M

    2015-12-01

    A novel algorithm has been developed and validated to isolate individual papermaking fibres in micro-computed tomographic images of paper handsheets as a first step to characterize the structure of the paper. The three-step fibre segmentation algorithm segments the papermaking fibres by (i) tracking the hollow inside the fibres via a modified connected component methodology, (ii) extracting the fibre walls using a distance transform and (iii) labelling the fibres through collapsed sections by a final refinement step. Furthermore, postprocessing algorithms have been developed to calculate the length and coarseness of the segmented fibres. The fibre segmentation algorithm is the first ever reported method for the automated segmentation of the tortuous three-dimensional morphology of papermaking fibres within microstructural images of paper handsheets. The method is not limited to papermaking fibres, but can be applied to any material consisting of tortuous and hollow fibres. PMID:26301453

  4. Use of Spun optical fibres in current sensors

    SciTech Connect

    Gubin, Vladimir P; Isaev, Victor A; Morshnev, Sergey K; Sazonov, Aleksandr I; Starostin, Nikolay I; Chamorovsky, Yury K; Oussov, Aleksey I

    2006-03-31

    The polarisation properties of a Spun optical fibre are studied in connection with their applications in fibreoptic current sensors based on the Faraday effect. A model of this fibre is proposed which represents it as an anisotropic medium with the spiral structure of the fast and slow birefringence axes. A sensor is developed based on an all-fibre low-coherence linear interferometer with a threshold sensitivity of 70 mA Hz{sup -1/2}, a maximum measured current of 3000 A, and a scale-factor reproducibility of {+-}0.6%. It is found that for a given diameter of the fibre contour, the normalised sensitivity is independent of the fibre length. The experimental results confirm the theory. (laser applications and other topics in quantum electronics)

  5. Design and construction of the fibre system for FMOS

    NASA Astrophysics Data System (ADS)

    Murray, Graham J.; Dodsworth, George N.; Content, Robert; Tamura, Naoyuki

    2008-07-01

    A consortium of Japanese, Australian and UK groups has developed a fibre-fed near IR (J & H band) multi-object spectrographic facility (FMOS) for the Subaru telescope. In this second-generation instrument, a novel prime focus 400-fibre multi-object positioning system, ECHIDNA, is optically linked via twin cables to dual IR spectrographs. The spectrographs are located some distance away, on a dedicated platform two levels above Nasmyth. The Centre for Advanced Instrumentation at Durham University oversaw the design and construction of the optical fibre system linking ECHIDNA to the spectrographs. A modularised connector within the cable scheme and an integral back illumination unit additionally featured as part of the Durham work-package. At the time of writing (mid 2008) FMOS, including the fibre system, is installed and functional on-telescope, with commissioning currently underway. This paper provides an overview of the design and construction of the optical fibre system.

  6. Advanced materials and techniques for fibre-optic sensing

    NASA Astrophysics Data System (ADS)

    Henderson, Philip J.

    2014-06-01

    Fibre-optic monitoring systems came of age in about 1999 upon the emergence of the world's first significant commercialising company - a spin-out from the UK's collaborative MAST project. By using embedded fibre-optic technology, the MAST project successfully measured transient strain within high-performance composite yacht masts. Since then, applications have extended from smart composites into civil engineering, energy, military, aerospace, medicine and other sectors. Fibre-optic sensors come in various forms, and may be subject to embedment, retrofitting, and remote interrogation. The unique challenges presented by each implementation require careful scrutiny before widespread adoption can take place. Accordingly, various aspects of design and reliability are discussed spanning a range of representative technologies that include resonant microsilicon structures, MEMS, Bragg gratings, advanced forms of spectroscopy, and modern trends in nanotechnology. Keywords: Fibre-optic sensors, fibre Bragg gratings, MEMS, MOEMS, nanotechnology, plasmon.

  7. Physicochemical characterization of oil palm mesocarp fibre treated with glycerol

    NASA Astrophysics Data System (ADS)

    Nor Hamizah M., A.; Roila, A.; Rahimi M., Y.

    2015-09-01

    Lignocellulose has been identified as another source for conversion into value added products. In the present work, physicochemical features from the oil palm mesocarp fibre treated by using pure glycerol with 2% (w/w) NaOH catalyst and crude glycerol have been studied. Treatment was conducted at temperatures 150 °C for 60 min. Fibre treated by crude glycerol resulted in high percentages of holocellulose and lower content of insoluble lignin. These results suggest that crude glycerol can be used as an alternative solvent for pretreatment process. The characterization treated fibre by means of FTIR and TGA has shown significant differences compared to untreated fibre. It was revealed that treated fibre successful eliminated hemicellulose and reduce of lignin content.

  8. Multifunctional, supramolecular, continuous artificial nacre fibres

    PubMed Central

    Hu, Xiaozhen; Xu, Zhen; Gao, Chao

    2012-01-01

    Nature has created amazing materials during the process of evolution, inspiring scientists to studiously mimic them. Nacre is of particular interest, and it has been studied for more than half-century for its strong, stiff, and tough attributes resulting from the recognized “brick-and-mortar” (B&M) layered structure comprised of inorganic aragonite platelets and biomacromolecules. The past two decades have witnessed great advances in nacre-mimetic composites, but they are solely limited in films with finite size (centimetre-scale). To realize the adream target of continuous nacre-mimics with perfect structures is still a great challenge unresolved. Here, we present a simple and scalable strategy to produce bio-mimic continuous fibres with B&M structures of alternating graphene sheets and hyperbranched polyglycerol (HPG) binders via wet-spinning assembly technology. The resulting macroscopic supramolecular fibres exhibit excellent mechanical properties comparable or even superior to nacre and bone, and possess fine electrical conductivity and outstanding corrosion-resistance. PMID:23097689

  9. Spiders spinning electrically charged nano-fibres

    PubMed Central

    Kronenberger, Katrin; Vollrath, Fritz

    2015-01-01

    Most spider threads are on the micrometre and sub-micrometre scale. Yet, there are some spiders that spin true nano-scale fibres such as the cribellate orb spider, Uloborus plumipes. Here, we analyse the highly specialized capture silk-spinning system of this spider and compare it with the silk extrusion systems of the more standard spider dragline threads. The cribellar silk extrusion system consists of tiny, morphologically basic glands each terminating through exceptionally long and narrow ducts in uniquely shaped silk outlets. Depending on spider size, hundreds to thousands of these outlet spigots cover the cribellum, a phylogenetically ancient spinning plate. We present details on the unique functional design of the cribellate gland–duct–spigot system and discuss design requirements for its specialist fibrils. The spinning of fibres on the nano-scale seems to have been facilitated by the evolution of a highly specialist way of direct spinning, which differs from the aqua-melt silk extrusion set-up more typical for other spiders. PMID:25631231

  10. Hydrodynamics of diatom chains and semiflexible fibres.

    PubMed

    Nguyen, Hoa; Fauci, Lisa

    2014-07-01

    Diatoms are non-motile, unicellular phytoplankton that have the ability to form colonies in the form of chains. Depending upon the species of diatoms and the linking structures that hold the cells together, these chains can be quite stiff or very flexible. Recently, the bending rigidities of some species of diatom chains have been quantified. In an effort to understand the role of flexibility in nutrient uptake and aggregate formation, we begin by developing a three-dimensional model of the coupled elastic-hydrodynamic system of a diatom chain moving in an incompressible fluid. We find that simple beam theory does a good job of describing diatom chain deformation in a parabolic flow when its ends are tethered, but does not tell the whole story of chain deformations when they are subjected to compressive stresses in shear. While motivated by the fluid dynamics of diatom chains, our computational model of semiflexible fibres illustrates features that apply widely to other systems. The use of an adaptive immersed boundary framework allows us to capture complicated buckling and recovery dynamics of long, semiflexible fibres in shear. PMID:24789565

  11. Multifunctional, supramolecular, continuous artificial nacre fibres

    NASA Astrophysics Data System (ADS)

    Hu, Xiaozhen; Xu, Zhen; Gao, Chao

    2012-10-01

    Nature has created amazing materials during the process of evolution, inspiring scientists to studiously mimic them. Nacre is of particular interest, and it has been studied for more than half-century for its strong, stiff, and tough attributes resulting from the recognized ``brick-and-mortar'' (B&M) layered structure comprised of inorganic aragonite platelets and biomacromolecules. The past two decades have witnessed great advances in nacre-mimetic composites, but they are solely limited in films with finite size (centimetre-scale). To realize the adream target of continuous nacre-mimics with perfect structures is still a great challenge unresolved. Here, we present a simple and scalable strategy to produce bio-mimic continuous fibres with B&M structures of alternating graphene sheets and hyperbranched polyglycerol (HPG) binders via wet-spinning assembly technology. The resulting macroscopic supramolecular fibres exhibit excellent mechanical properties comparable or even superior to nacre and bone, and possess fine electrical conductivity and outstanding corrosion-resistance.

  12. Alignement automatise de fibres optiques amorces monomodes

    NASA Astrophysics Data System (ADS)

    St-Amant, Yves

    Cette these jette les bases necessaires au developpement d'algorithmes a base de modele pour l'automatisation de l'alignement de fibres amorces monomodes. A partir de la methode de l'integrale de recouvrement et de deux solutions approximatives existantes, un modele analytique d'efficacite de couplage optique permettant d'estimer la puissance transmise entre un composant et une fibre amorce monomode est d'abord formule. Avec celui-ci, sept proprietes pouvant etre utiles au developpement d'algorithmes a base de modele sont ensuite identifiees et validees. Enfin, a l'aide de ces proprietes, une strategie d'alignement a base de modele est developpee et validee experimentalement. Les resultats obtenus demontrent clairement la repetitivite, la robustesse, la precision et la rapidite de la strategie proposee. Ils demontrent aussi qu'il est possible de realiser un alignement complet sans l'utilisation de systemes auxiliaires tels des systemes de vision, des cameras infrarouges, des capteurs de contact ou des systemes de fixation hautement precis.

  13. Fibre reinforced composites in aircraft construction

    NASA Astrophysics Data System (ADS)

    Soutis, C.

    2005-02-01

    Fibrous composites have found applications in aircraft from the first flight of the Wright Brothers’ Flyer 1, in North Carolina on December 17, 1903, to the plethora of uses now enjoyed by them on both military and civil aircrafts, in addition to more exotic applications on unmanned aerial vehicles (UAVs), space launchers and satellites. Their growing use has risen from their high specific strength and stiffness, when compared to the more conventional materials, and the ability to shape and tailor their structure to produce more aerodynamically efficient structural configurations. In this paper, a review of recent advances using composites in modern aircraft construction is presented and it is argued that fibre reinforced polymers, especially carbon fibre reinforced plastics (CFRP) can and will in the future contribute more than 50% of the structural mass of an aircraft. However, affordability is the key to survival in aerospace manufacturing, whether civil or military, and therefore effort should be devoted to analysis and computational simulation of the manufacturing and assembly process as well as the simulation of the performance of the structure, since they are intimately connected.

  14. Quantum cryptography on multiuser optical fibre networks

    NASA Astrophysics Data System (ADS)

    Townsend, Paul D.

    1997-01-01

    To establish a secure communication channel, it is necessary to distribute between two users a key which allows safe encryption and decryption of messages. But because decryption is a simple task for any key holder, it is crucial that the key remains secret during distribution. Secrecy cannot be guaranteed if distribution occurs on the basis of classical physical mechanisms, as it is impossible to know whether the key has been intercepted during transmission. Quantum cryptography1-3 provides a fundamental solution to this problem. When quantum-mechanical processes are used to establish the key, any eavesdropping during transmission leads to an unavoidable and detectable disturbance in the received key information. Quantum cryptography has been demonstrated using standard telecommunication fibres linking single pairs of users4-8, but practical implementations will require communication networks with many users9. Here I introduce a practical scheme for multi-user quantum cryptography, and demonstrate its operation on an optical fibre network. The scheme enables a single controller on the network to establish, and regularly update, a distinct secret key with each network user. These keys can then be used to securely encrypt conventional data transmissions that are broadcast on the network.

  15. Hydrodynamics of diatom chains and semiflexible fibres

    PubMed Central

    Nguyen, Hoa; Fauci, Lisa

    2014-01-01

    Diatoms are non-motile, unicellular phytoplankton that have the ability to form colonies in the form of chains. Depending upon the species of diatoms and the linking structures that hold the cells together, these chains can be quite stiff or very flexible. Recently, the bending rigidities of some species of diatom chains have been quantified. In an effort to understand the role of flexibility in nutrient uptake and aggregate formation, we begin by developing a three-dimensional model of the coupled elastic–hydrodynamic system of a diatom chain moving in an incompressible fluid. We find that simple beam theory does a good job of describing diatom chain deformation in a parabolic flow when its ends are tethered, but does not tell the whole story of chain deformations when they are subjected to compressive stresses in shear. While motivated by the fluid dynamics of diatom chains, our computational model of semiflexible fibres illustrates features that apply widely to other systems. The use of an adaptive immersed boundary framework allows us to capture complicated buckling and recovery dynamics of long, semiflexible fibres in shear. PMID:24789565

  16. Silica optical fibers: technology update

    NASA Astrophysics Data System (ADS)

    Krohn, David A.; McCann, Brian P.

    1995-05-01

    Silica-core optical fibers have long been the standard delivery medium for medical laser delivery systems. Their high strength, excellent flexibility, and low cost continue to make them the fiber of choice for systems operating from 300 to 2200 nm. An overview of the current fiber constructions available to the industry is reviewed. Silicone-clad fibers, hard- fluoropolymer clad fibers and silica-clad fibers are briefly compared in terms of mechanical and optical properties. The variety of fiber coatings available is also discussed. A significant product development of silica fiber delivery systems has been in side-firing laser delivery systems for Urology. These devices utilize silica-core fibers to project the laser energy at a substantial lateral angle to the conventional delivery system, typically 40 to 100 degrees off axis. Many unique distal tips have been designed to meet the needs of this potentially enormous application. There are three primary technologies employed in side-firing laser delivery systems: reflection off of an attached medium; reflection within an angle-polished fiber through total internal reflection; and reflection from both an angle-polished fiber and an outside medium. Each technology is presented and compared on the basis of operation modality, transmission efficiency, and power-handling performance.

  17. The Phagocytosis and Toxicity of Amorphous Silica

    PubMed Central

    Costantini, Lindsey M.; Gilberti, Renée M.; Knecht, David A.

    2011-01-01

    Background Inhalation of crystalline silica is known to cause an inflammatory reaction and chronic exposure leads to lung fibrosis and can progress into the disease, silicosis. Cultured macrophages bind crystalline silica particles, phagocytose them, and rapidly undergo apoptotic and necrotic death. The mechanism by which particles are bound and internalized and the reason particles are toxic is unclear. Amorphous silica has been considered to be a less toxic form, but this view is controversial. We compared the uptake and toxicity of amorphous silica to crystalline silica. Methodology/Principal Findings Amorphous silica particles are phagocytosed by macrophage cells and a single internalized particle is capable of killing a cell. Fluorescent dextran is released from endo-lysosomes within two hours after silica treatment and Caspase-3 activation occurs within 4 hours. Interestingly, toxicity is specific to macrophage cell lines. Other cell types are resistant to silica particle toxicity even though they internalize the particles. The large and uniform size of the spherical, amorphous silica particles allowed us to monitor them during the uptake process. In mCherry-actin transfected macrophages, actin rings began to form 1-3 minutes after silica binding and the actin coat disassembled rapidly following particle internalization. Pre-loading cells with fluorescent dextran allowed us to visualize the fusion of phagosomes with endosomes during internalization. These markers provided two new ways to visualize and quantify particle internalization. At 37°C the rate of amorphous silica internalization was very rapid regardless of particle coating. However, at room temperature, opsonized silica is internalized much faster than non-opsonized silica. Conclusions/Significance Our results indicate that amorphous and crystalline silica are both phagocytosed and both toxic to mouse alveolar macrophage (MH-S) cells. The pathway leading to apoptosis appears to be similar in both

  18. Modified sensing element of a fibre-optic current sensor based on a low-eigenellipticity spun fibre

    SciTech Connect

    Przhiyalkovsky, Ya V; Morshnev, S K; Starostin, N I; Gubin, V P

    2014-10-31

    We have proposed and investigated a modified sensing element of a spun fibre current sensor for the case when the beat length of the built-in linear birefringence of the fibre is equal to or less than the spin pitch of its helical structure. The proposed configuration makes it possible to restore the interferometer contrast reduced because of the decrease in the ellipticity of the wavelength-averaged polarisation state of radiation propagating in such spun fibre. The modified sensing element contains two polarisation state converters: one, located at the spun fibre input, produces polarisation with ellipticity equal to the eigenellipticity of the fibre, and the other ensures conversion of the elliptical polarisation to an orthogonal one through mirror reflection at the fibre output. We have also demonstrated that the magneto-optical sensitivity decreases slightly for the analysed spectrum-averaged parameters of the polarisation state of radiation in the spun fibre. Experimental data lend support to the theoretical predictions. (fibre-optic sensors)

  19. FRD in optical fibres at low temperatures: investigations for Gemini's Wide-field Fibre Multi-Object Spectrograph

    NASA Astrophysics Data System (ADS)

    de Oliveira, A. C.; de Oliveira, L. S.; Dos Santos, J. B.; Arruda, M. V.; Dos Santos, L. G. C.; Rodrigues, F.; de Castro, F. L. F.

    2011-06-01

    While there is no direct evidence for the deterioration in Focal Ratio Degradation (FRD) of optical fibres in severe temperature gradients, the fibre ends inserted into metallic containment devices such as steel ferrules can be a source of stress, and hence increased FRD at low temperatures. In such conditions, instruments using optical fibres may suffer some increase in FRD and consequent loss of system throughput when they are working in environments with significant thermal gradients, a common characteristic of ground-based observatories. In this paper we present results of experiments with optical fibres inserted in different materials as a part of our prototyping study for Gemini's Wide-field Multi-Object Spectrograph (WFMOS) project. Thermal effects and the use of new holding techniques will be discussed in the context of Integral Field Units and multi-fibres systems. In this work, we have used careful methodologies that give absolute measurements of FRD to quantify the advantages of using epoxy-based composites rather than metals as support structures for the fibre ends. This is shown to be especially important in minimizing thermally induced stresses in the fibre terminations. Not only is this important for optimizing fibre spectrograph performance but the benefits of using such materials are demonstrated in the minimization of positional variations and the avoidance of metal-to-glass delamination. Furthermore, by impregnating the composites with small zirconium oxide particles the composite materials supply their own fine polishing grit which aids significantly to the optical quality of the finished product.

  20. Detection of the volatile organic compounds emitted from paints using optical fibre long period grating modified with the mesoporous nano-scale coating

    NASA Astrophysics Data System (ADS)

    Hromadka, Jiri; James, Stephen; Davis, Frank; Tatam, Ralph P.; Crump, Derrick; Korposh, Sergiy

    2015-09-01

    An optical fibre long period grating (LPG) modified with a mesoporous film infused with a calixarene as a functional compound was employed for the detection of a mixture of volatile organic compounds (VOCs). The sensing mechanism is based on the transduction of the refractive index change induced by the complexion of the VOCs with calixarene into a change in the form of the transmission spectrum of the LPG. An LPG, modified with a calixarene-infused coating comprising 5 cycles of silica nanoparticles/poly(allylamine hydrochloride) polycation (SiO2/PAH), was exposed to mixture of VOCs emitted from paint at conditions simulating ISO standards test (16000-10).

  1. Uranium incorporation into amorphous silica.

    PubMed

    Massey, Michael S; Lezama-Pacheco, Juan S; Nelson, Joey M; Fendorf, Scott; Maher, Kate

    2014-01-01

    High concentrations of uranium are commonly observed in naturally occurring amorphous silica (including opal) deposits, suggesting that incorporation of U into amorphous silica may represent a natural attenuation mechanism and promising strategy for U remediation. However, the stability of uranium in opaline silicates, determined in part by the binding mechanism for U, is an important factor in its long-term fate. U may bind directly to the opaline silicate matrix, or to materials such as iron (hydr)oxides that are subsequently occluded within the opal. Here, we examine the coordination environment of U within opaline silica to elucidate incorporation mechanisms. Precipitates (with and without ferrihydrite inclusions) were synthesized from U-bearing sodium metasilicate solutions, buffered at pH ∼ 5.6. Natural and synthetic solids were analyzed with X-ray absorption spectroscopy and a suite of other techniques. In synthetic amorphous silica, U was coordinated by silicate in a double corner-sharing coordination geometry (Si at ∼ 3.8-3.9 Å) and a small amount of uranyl and silicate in a bidentate, mononuclear (edge-sharing) coordination (Si at ∼ 3.1-3.2 Å, U at ∼ 3.8-3.9 Å). In iron-bearing synthetic solids, U was adsorbed to iron (hydr)oxide, but the coordination environment also contained silicate in both edge-sharing and corner-sharing coordination. Uranium local coordination in synthetic solids is similar to that of natural U-bearing opals that retain U for millions of years. The stability and extent of U incorporation into opaline and amorphous silica represents a long-term repository for U that may provide an alternative strategy for remediation of U contamination. PMID:24984107

  2. Simulation of inertial fibre orientation in turbulent flow

    NASA Astrophysics Data System (ADS)

    Njobuenwu, Derrick O.; Fairweather, Michael

    2016-06-01

    The spatial and orientational behaviour of fibres within a suspension influences the rheological and mechanical properties of that suspension. An Eulerian-Lagrangian framework to simulate the behaviour of fibres in turbulent flows is presented. The framework is intended for use in simulations of non-spherical particles with high Reynolds numbers, beyond the Stokesian regime, and is a computationally efficient alternative to existing Stokesian models for fibre suspensions in turbulent flow. It is based on modifying available empirical drag correlations for the translation of non-spherical particles to be orientation dependent, accounting for the departure in shape from a sphere. The orientational dynamics of a particle is based on the framework of quaternions, while its rotational dynamics is obtained from the solution of the Euler equation of rotation subject to external torques on the particle. The fluid velocity and turbulence quantities are obtained using a very high-resolution large eddy simulation with dynamic calibration of the sub-grid scale energy containing fluid motions. The simulation matrix consists of four different fibre Stokes numbers (St = 1, 5, 25, and 125) and five different fibre aspect ratios (λ = 1.001, 3, 10, 30, and 50), with results considered at four distances from a channel wall (in the viscous sub-layer, buffer, and fully turbulent regions), which are taken as a measure of the flow velocity gradient, all at a constant fibre to fluid density ratio (ρp/ρ = 760) and shear Reynolds number Reτ = 150. The simulated fibre orientation, concentration, and streakiness confirm previous experimentally observed characteristics of fibre behaviour in turbulence, and that of direct numerical simulations of fibres in Stokesian, or creeping flow, regimes. The fibres exhibit translational motion similar to spheres, where they tend to accumulate in the near-wall (viscous sub-layer and buffer) region and preferentially concentrate in regions of low

  3. Fibre intake and incident colorectal cancer depending on fibre source, sex, tumour location and Tumour, Node, Metastasis stage.

    PubMed

    Vulcan, Alexandra; Brändstedt, Jenny; Manjer, Jonas; Jirström, Karin; Ohlsson, Bodil; Ericson, Ulrika

    2015-09-28

    Studies on fibre intake and incident colorectal cancer (CRC) indicate inverse associations. Differences by tumour stage have not been examined. We examined associations between fibre intake and its sources, and incidental CRC. Separate analyses were carried out on the basis of sex, tumour location and the Tumour, Node, Metastasis (TNM) classification. The Malmö Diet and Cancer Study is a population-based cohort study, including individuals aged 45-74 years. Dietary data were collected through a modified diet history method. The TNM classification was obtained from pathology/clinical records and re-evaluated. Among 27 931 individuals (60% women), we found 728 incident CRC cases during 428 924 person-years of follow-up. Fibre intake was inversely associated with CRC risk (P(trend) = 0.026). Concerning colon cancer, we observed borderline interaction between fibre intake and sex (P = 0.052) and significant protective association restricted to women (P(trend) = 0.013). Intake of fruits and berries was inversely associated with colon cancer in women (P(trend) = 0.022). We also observed significant interactions between intakes of fibre (P = 0.048) and vegetables (P = 0.039) and sex on rectal cancer, but no significant associations were seen between intake of fibre, or its sources, in either of the sexes. Except for inverse associations between intake of fibre-rich cereal products and N0- and M0-tumours, we did not observe significant associations with different TNM stages. Our findings suggest different associations between fibre intake and CRC depending on sex, tumour site and fibre source. High fibre intake, especially from fruits and berries, may, above all, prevent tumour development in the colon in women. No clear differences by TNM classification were detected. PMID:26281852

  4. Adsorption of organic molecules on silica surface.

    PubMed

    Parida, Sudam K; Dash, Sukalyan; Patel, Sabita; Mishra, B K

    2006-09-13

    The adsorption behaviour of various organic adsorbates on silica surface is reviewed. Most of the structural information on silica is obtained from IR spectral data and from the characteristics of water present at the silica surface. Silica surface is generally embedded with hydroxy groups and ethereal linkages, and hence considered to have a negative charged surface prone to adsorption of electron deficient species. Adsorption isotherms of the adsorbates delineate the nature of binding of the adsorbate with silica. Aromatic compounds are found to involve the pi-cloud in hydrogen bonding with silanol OH group during adsorption. Cationic and nonionic surfactants adsorb on silica surface involving hydrogen bonding. Sometimes, a polar part of the surfactants also contributes to the adsorption process. Styryl pyridinium dyes are found to anchor on silica surface in flat-on position. On modification of the silica by treating with alkali, the adsorption behaviour of cationic surfactant or polyethylene glycol changes due to change in the characteristics of silica or modified silica surface. In case of PEG-modified silica, adsolubilization of the adsorbate is observed. By using a modified adsorption equation, hemimicellization is proposed for these dyes. Adsorptions of some natural macromolecules like proteins and nucleic acids are investigated to study the hydrophobic and hydrophilic binding sites of silica. Artificial macromolecules like synthetic polymers are found to be adsorbed on silica surface due to the interaction of the multifunctional groups of the polymers with silanols. Preferential adsorption of polar adsorbates is observed in case of adsorbate mixtures. When surfactant mixtures are considered to study competitive adsorption on silica surface, critical micelle concentration of individual surfactant also contributes to the adsorption isotherm. The structural study of adsorbed surface and the thermodynamics of adsorption are given some importance in this review

  5. Interrogation of fibre Bragg gratings through a fibre optic rotary joint on a geotechnical centrifuge

    NASA Astrophysics Data System (ADS)

    Correia, Ricardo; James, Stephen W.; Marshall, Alec; Heron, Charles; Korposh, Sergiy

    2016-05-01

    The monitoring of an array of fibre Bragg gratings (FBGs) strain sensors was performed through a single channel, single mode fibre optic rotary joint (FORJ) mounted on a geotechnical centrifuge. The array of three FBGs was attached to an aluminum plate that was anchored at the ends and placed on the model platform of the centrifuge. Acceleration forces of up to 50g were applied and the reflection signal of the monitored FBGs recorded dynamically using a 2.5kHz FBG interrogator placed outside the centrifuge. The use of a FORJ allowed the monitoring of the FBGs without submitting the FBG interrogator to the high g-forces experienced in the centrifuge.

  6. Effect of Thickness and Fibre Volume Fraction on Impact Resistance of Steel Fibre Reinforced Concrete (SFRC)

    NASA Astrophysics Data System (ADS)

    Che Muda, Zakaria; Usman, Fathoni; Syamsir, Agusril; Shao Yang, Chen; Nasharuddin Mustapha, Kamal; Beddu, Salmia; Thiruchelvam, Sivadass; Liyana Mohd Kamal, Nur; Ashraful Alam, Md; Birima, Ahmed H.; Itam, Zarina; Zaroog, O. S.

    2016-03-01

    This paper investigate the effect of the thickness and fibre volume fraction (VF) on the impact performance of steel fibre reinforced concrete (SFRC) for the concrete slab of 300mm × 300mm size reinforced subjected to low impact projectile test. A self-fabricated drop-weight impact test rig with a steel ball weight of 1.236 kg drop at 0.57 m height has been used in this research work. The objective of this research is to study the relationship of impact resistance SFRC against slab thickness and volume fraction. There is a good linear correlation between impact resistances of SFRC against slab thickness. However the impact resistance of SFRC against percentage of volume fraction exhibit a non-linear relationship.

  7. Bismuth-doped telecommunication fibres for lasers and amplifiers in the 1400-1500-nm region

    SciTech Connect

    Dvoirin, V V; Mashinskii, V M; Medvedkov, O I; Dianov, Evgenii M; Umnikov, A A; Gur'yanov, Aleksei N

    2009-06-30

    Bismuth-doped optical fibres fully compatible with standard telecommunication fibres are developed. Lasers based on such fibres emitting in the spectral range 1430-1500 nm with an efficiency of up to 7.6% at room temperature and up to 10.5% at a temperature of -65{sup 0}C are fabricated. (waveguides. optical fibres)

  8. Potential Benefits of Dietary Fibre Intervention in Inflammatory Bowel Disease

    PubMed Central

    Wong, Celestine; Harris, Philip J.; Ferguson, Lynnette R.

    2016-01-01

    Intestinal dysbiosis is thought to be an important cause of disease progression and the gastrointestinal symptoms experienced in patients with inflammatory bowel disease (IBD). Inflammation appears to be a major contributor in perpetuating a dysregulated gut microbiota. Although current drug therapies can significantly induce and maintain disease remission, there is no cure for these diseases. Nevertheless, ongoing human studies investigating dietary fibre interventions may potentially prove to exert beneficial outcomes for IBD. Postulated mechanisms include direct interactions with the gut mucosa through immunomodulation, or indirectly through the microbiome. Component species of the microbiome may degrade dietary-fibre polysaccharides and ferment the products to form short-chain fatty acids such as butyrate. Prebiotic dietary fibres may also act more directly by altering the composition of the microbiome. Longer term benefits in reducing the risk of more aggressive disease or colorectal cancer may require other dietary fibre sources such as wheat bran or psyllium. By critically examining clinical trials that have used dietary fibre supplements or dietary patterns containing specific types or amounts of dietary fibres, it may be possible to assess whether varying the intake of specific dietary fibres may offer an efficient treatment for IBD patients. PMID:27314323

  9. Can supplementary dietary fibre suppress breast cancer growth?

    PubMed Central

    Stoll, B. A.

    1996-01-01

    Case-control studies in diverse populations around the world have reported a lower risk of breast cancer in association with higher intake of dietary fibre and complex carbohydrates. Although this has not been confirmed in prospective studies in the USA, the observations have prompted the hypothesis that prolonged use of dietary fibre supplements might reduce breast cancer risk in high-incidence populations. Several possible mechanisms of action have been suggested, all involving a reduction of bioactive oestrogen levels in the blood. The various mechanisms are not necessarily mutually exclusive. First, a high-fibre diet might reduce circulating oestrogen levels by reducing the enterohepatic recirculation of oestrogen. Second, many plants and vegetables contain isoflavones and lignans capable of conversion in the bowel into weak oestrogens that may compete with oestradiol for target binding-sites. Third, a high-fibre diet is less often associated with obesity, which tends to increase availability of the biologically active 16-alpha metabolites of oestrone. Fourth, a high-fibre diet usually has a lower content of fat and a higher content of antioxidant vitamins, which may protect against breast cancer risk. Finally, diets rich in fibre and complex carbohydrates have been shown to improve insulin sensitivity, with an associated reduction in circulating oestrogen levels. Synergism between these effects offers a possible mechanism by which a high fibre intake might suppress breast cancer growth in women. PMID:8605086

  10. REVIEW ARTICLE Fibre optic devices produced by arc discharges

    NASA Astrophysics Data System (ADS)

    Rego, G.

    2010-11-01

    We present an overview of the applications of the electric arc technique related to optical fibre technology. The use of arc discharges ranges from the well-known fibre splicing, going through the fabrication of basic devices such as fibre tapers and microspheres, to tailoring the spectra of UV-induced gratings such as in the apodization of fibre Bragg gratings and also in the fabrication of phase-shifted and sampled fibre Bragg gratings. However, in the past decade a topic more intensively investigated was probably long-period fibre gratings. Therefore, some devices based on arc-induced gratings, namely, phase-shifted and step-changed gratings and bandpass filters are discussed. We also present an electrically insulated thermocouple assembled in situ using arc discharges. This sensor is very useful in the determination of the temperature attained by the fibre during an arc discharge, this property being fundamental for the discussion of the mechanisms of formation and for the understanding of the thermal properties of arc-induced devices.

  11. Histochemical and functional fibre typing of the rabbit masseter muscle.

    PubMed Central

    Bredman, J J; Weijs, W A; Moorman, A F; Brugman, P

    1990-01-01

    The fibre-type distribution of the masseter muscle of the rabbit was studied by means of the myosin-ATPase and succinate dehydrogenase reactions. Six different fibre types were found and these were unequally distributed between and within the anatomical compartments of the muscle. Most of the masseter consists of slow- and fast-twitch oxidative fibres. The slow fibres increase in numbers in the deeper and more anterior regions of the muscle. Fast-twitch glycolytic fibres were almost exclusively found in the most posterior portions of the superficial and deep masseter. The fibre composition within the sagittally orientated anatomical compartments was found to be correlated with maximal contraction speeds during natural mastication as estimated from a mechanical model. However, the differences in fibre composition between the anatomical compartments (and hence between superficial and deep layers) appeared not to be correlated with contraction speed. The regional and compartmental specialisation within the masseter permits the muscle to perform many different functional roles in the generation and control of the jaw movements, jaw position and bite forces. Images Fig. 2 Fig. 4 Fig. 6 PMID:2139021

  12. Reinforcement of porous alginate scaffolds by incorporating electrospun fibres.

    PubMed

    Sakai, Shinji; Takagi, Yousuke; Yamada, Yusuke; Yamaguchi, Tetsu; Kawakami, Koei

    2008-09-01

    The mechanical properties of scaffolds play a vital role in transmitting input mechanical signals to the cells within them. We aimed to modify mechanical properties of porous scaffolds by incorporating electrospun fibres into their frameworks. Porous constructs containing electrospun silicate fibres were prepared from Na-alginate aqueous solutions suspending the silicate fibres with (ASF) or without amino groups (NASF) via an all-aqueous method based on a freeze-drying technique. The repulsion forces of constructs containing ASF towards compression increased as the fibre content increased. In contrast, constructs containing NASF showed no such increases in repulsion forces. Cells seeded onto constructs containing ASF exhibited suppressed growth, similar to cells seeded onto alginate scaffolds without fibres. In contrast, cells seeded onto scaffolds containing NASF showed about two-fold faster growth than cells seeded onto scaffolds containing ASF. The differences in the mechanical properties and cell growth profiles between the scaffolds containing ASF and NASF can be explained by the formation and non-formation of electrostatic bonds between the fibres and alginate, respectively. The results obtained in the present study demonstrate the feasibility of incorporating electrospun fibres for reinforcement of alginate scaffolds and enhancement of cell growth. PMID:18689918

  13. Fibre optic systems for gas detection principals, progress and prospects

    NASA Astrophysics Data System (ADS)

    Culshaw, Brian

    2010-11-01

    Gas sensing is evolving into an important application contributing particularly to environmental and safety monitoring. Fibre optic sensing will have an important role to play as the need for gas measurements increase. This paper seeks to overview of the optical techniques which are compatible with fibre optic technology and present a limited snapshot of the applications. Fibre optic techniques offer intrinsic safety, reliability and very long interrogation distances over the fibre link together with prospects for highly multiplexed and distributed systems. There are two basic approaches for fibre sensing targeted at gas measurements. The first involves some intermediate compound in contact with the end of the fibre (or deposited along the fibre) whose optical properties change with the presence of the gas of interest, usually measured spectroscopically. The second involves direct absorption spectroscopy typically in the near infrared. Former techniques are invariably responsive to a number of gas species and are usually difficult to calibrate accurately. The latter techniques are highly gas specific and can be accurately calibrated. However both approaches have their application sectors depending upon particular measurement requirements. The paper presents a brief overview of the principles of both these techniques and analyses some of their applications.

  14. Electron beam irradiation in natural fibres reinforced polymers (NFRP)

    NASA Astrophysics Data System (ADS)

    Kechaou, B.; Salvia, M.; Fakhfakh, Z.; Juvé, D.; Boufi, S.; Kallel, A.; Tréheux, D.

    2008-11-01

    This study focuses on the electric charge motion in unsatured polyester and epoxy composites reinforced by natural fibres of Alfa type, treated by different coupling agents. The electric charging phenomenon is studied by scanning electron microscopy mirror effect (SEMME) coupled with the induced current method (ICM). Previously, using the same approach, glass fibre reinforced epoxy (GFRE) was studied to correlate mechanical [B. Kchaou, C. Turki, M. Salvia, Z. Fakhfakh, D. Tréheux, Composites Science and Technology 64 (2004) 1467], or tribological [B. Kchaou, C. Turki, M. Salvia, Z. Fakhfakh, D. Tréheux, Dielectric and friction behaviour of unidirectionalglass fibre reinforced epoxy (GFRE), Wear, 265 (2008) 763.] properties and dielectric properties. It was shown that the dielectric properties of the fibre-matrix interfaces play a significant role in the optimization of the composite. This result seems to be the same for natural fibre composites: the fibre-matrix interfaces allow a diffusion of the electric charges which can delocalize the polarization energy and consequently delay the damage of the composite. However, a non-suited sizing can lead to a new trapping of electric charges along these same interfaces with, as a consequence, a localization of the polarisation energy. The optimum composite is obtained for one sizing which helps, at the same time, to have a strong fibre-matrix adhesion and an easy flow of the electric charges along the interface.

  15. Potential Benefits of Dietary Fibre Intervention in Inflammatory Bowel Disease.

    PubMed

    Wong, Celestine; Harris, Philip J; Ferguson, Lynnette R

    2016-01-01

    Intestinal dysbiosis is thought to be an important cause of disease progression and the gastrointestinal symptoms experienced in patients with inflammatory bowel disease (IBD). Inflammation appears to be a major contributor in perpetuating a dysregulated gut microbiota. Although current drug therapies can significantly induce and maintain disease remission, there is no cure for these diseases. Nevertheless, ongoing human studies investigating dietary fibre interventions may potentially prove to exert beneficial outcomes for IBD. Postulated mechanisms include direct interactions with the gut mucosa through immunomodulation, or indirectly through the microbiome. Component species of the microbiome may degrade dietary-fibre polysaccharides and ferment the products to form short-chain fatty acids such as butyrate. Prebiotic dietary fibres may also act more directly by altering the composition of the microbiome. Longer term benefits in reducing the risk of more aggressive disease or colorectal cancer may require other dietary fibre sources such as wheat bran or psyllium. By critically examining clinical trials that have used dietary fibre supplements or dietary patterns containing specific types or amounts of dietary fibres, it may be possible to assess whether varying the intake of specific dietary fibres may offer an efficient treatment for IBD patients. PMID:27314323

  16. Review on hygroscopic aging of cellulose fibres and their biocomposites.

    PubMed

    Mokhothu, Thabang H; John, Maya Jacob

    2015-10-20

    This review presents critical literature on effects of humidity and temperature on the properties of natural fibres and its composites. The drawback of moisture absorption on the mechanical properties of natural fibre and its composites is evaluated. Numerous researchers have been working to address the moisture absorption issue, with specific attention paid to the surface treatment of fibres and refining the fibre-matrix interface. Because of the natural fibre's positive commercial and environmental outcomes, as well as their desirable properties such as high specific strength, natural fibre reinforced composites are displaying a good potential to be used in various applications such as automotive, aerospace and packaging. This review addresses a comprehensive survey on hygroscopic factors (long term environmental aging) affecting natural fibres and their performance as reinforcement in polymer composites. The effects of cellulose surface chemistry and topography on hydrophobicity are addressed. Furthermore, the review also addresses the progress in the development of superhydrophobic materials based on cellulose material for better moisture resistance. In addition, recent investigations dealing with bio-based coatings prepared from renewable resources are also discussed. PMID:26256193

  17. [Pleural lymphatics and pleural diseases related to fibres].

    PubMed

    Fleury Feith, J; Jaurand, M-C

    2013-12-01

    It is now well established that some pleural diseases, pleural plaques and malignant mesothelioma are related to asbestos fibre exposure although the mechanism of action of asbestos fibres is not fully understood. The development of artificial mineral fibres and carbon nanotubes, which share some morphological characteristics similar to asbestos fibres, is a present concern in the context of pleural diseases. Pleural plaques develop only in the parietal pleura, and in the 1990s, clinical observations have shown that the early development of mesothelioma also occurred on the parietal pleura. The peculiarity of the parietal pleura in contrast to the visceral pleura is the presence of "stomas" which are communication holes between the pleural cavity and the parietal pleura lymphatics. Morphological observations by thoracoscopy and experimental studies have shown that inhaled fibres translocate to the pleural space and, in human, are present in the parietal pleura at specific anthracotic areas (blackspots). Fibres accumulate on the stomas, up to block and locally induce an inflammatory reaction with cytokines release, that can be the bed of mesothelioma. However, despite the experimental data and observations in human pathology, the mechanisms of fibre translocation into the pleura is not yet clearly established. PMID:24210155

  18. Extracellular potentials of myelinated and demyelinated human motor nerve fibres.

    PubMed

    Stephanova, D I; Daskalova, M

    2003-12-01

    The extracellular potentials of myelinated and demyelinated human motor nerve fibres in an unbounded volume conductor are studied. Using our previous double-cable models of normal and demyelinated human fibres, the spatial and temporal intracellular potentials are calculated in the cases of point polarization and adaptation of the fibres. The intracellular potentials are then used as input to a line source model that allows to calculate the corresponding spatial and temporal extracellular potentials at various radial distances in the surrounding volume conductor. Four fibre demyelinations (termed as internodal focal\\systematic and paranodal focal\\systematic demyelinations, respectively) are studied. In all investigated cases, the radial decline of the peak-to-peak amplitude of the extracellular potential depends on the radial distance of the field point and increases with the increase of the distance. The results are consistent with the interpretation that the considerably different spatial and temporal distributions of the extracellular potentials depend not only on the cable properties of the fibres, but on the methods of fibre stimulation. In the case of fibre adaptation, the temporal extracellular potentials in the normal and demyelinated cases correspond well with electromyograms (EMGs) from healthy subjects and patients with demyelinated disorders as reported in the literature. Simulation results indicate that the models used are rather promising tools in studying the main properties of compound action potentials in patients with demyelinated disorders which up till now have not been sufficiently well understood. PMID:14717030

  19. A novel wireless mobile platform integrated with optical fibre sensors

    NASA Astrophysics Data System (ADS)

    Zhou, Bochao; Yang, Shuo; Sun, Tong; Grattan, Kenneth T. V.

    2014-05-01

    This paper presents a novel design of wireless mobile platform which enables effective integration of a number of optical fibre sensors with an advanced mobile wireless sensor network (WSN) and allows for potential applications such as monitoring in remote and harsh environments and tracking, exploiting fully the advantages offered both by mobile WSN and by advanced optical fibre sensing technologies. The platform which was designed and implemented consists of an optical fibre sensor module and a smart mobile WSN module, which shows important advantages for mobile sensing and tracking and mesh networking. In this study, a fibre Bragg grating (FBG)-based temperature sensor was specially designed and integrated successfully into the optical fibre sensor module as an exemplar to investigate the performance of the integrated system based on the mobile WSN platform. The positive experimental results obtained have confirmed the functionality of the platform designed and demonstrated its capacity for real-time optical fibre sensor data monitoring, processing and wireless transmission. The successful creation of this type of wireless mobile platform with optical fibre sensors would be expected to make an important impact on many sectors, where either conventional optical sensor designs or WSNs alone cannot meet the systems requirements.

  20. Global chromatin fibre compaction in response to DNA damage

    SciTech Connect

    Hamilton, Charlotte; Hayward, Richard L.; Gilbert, Nick

    2011-11-04

    Highlights: Black-Right-Pointing-Pointer Robust KAP1 phosphorylation in response to DNA damage in HCT116 cells. Black-Right-Pointing-Pointer DNA repair foci are found in soluble chromatin. Black-Right-Pointing-Pointer Biophysical analysis reveals global chromatin fibre compaction after DNA damage. Black-Right-Pointing-Pointer DNA damage is accompanied by rapid linker histone dephosphorylation. -- Abstract: DNA is protected by packaging it into higher order chromatin fibres, but this can impede nuclear processes like DNA repair. Despite considerable research into the factors required for signalling and repairing DNA damage, it is unclear if there are concomitant changes in global chromatin fibre structure. In human cells DNA double strand break (DSB) formation triggers a signalling cascade resulting in H2AX phosphorylation ({gamma}H2AX), the rapid recruitment of chromatin associated proteins and the subsequent repair of damaged sites. KAP1 is a transcriptional corepressor and in HCT116 cells we found that after DSB formation by chemicals or ionising radiation there was a wave of, predominantly ATM dependent, KAP1 phosphorylation. Both KAP1 and phosphorylated KAP1 were readily extracted from cells indicating they do not have a structural role and {gamma}H2AX was extracted in soluble chromatin indicating that sites of damage are not attached to an underlying structural matrix. After DSB formation we did not find a concomitant change in the sensitivity of chromatin fibres to micrococcal nuclease digestion. Therefore to directly investigate higher order chromatin fibre structures we used a biophysical sedimentation technique based on sucrose gradient centrifugation to compare the conformation of chromatin fibres isolated from cells before and after DNA DSB formation. After damage we found global chromatin fibre compaction, accompanied by rapid linker histone dephosphorylation, consistent with fibres being more regularly folded or fibre deformation being stabilized by

  1. Fermentation of dietary fibre components in the rat intestinal tract.

    PubMed

    Nyman, M; Asp, N G

    1982-05-01

    1. The fermentative breakdown of dietary fibre from various sources in the intestinal tract was studied using rat balance experiments and gas-liquid chromatograhic analysis of dietary fibre monomers in feed and faces. 2. On a basal diet with 690 g maize starch/kg but no added fibre, small but detectable amounts of polymeric glucose, rhamnose, arabinose, xylose, galactose, mannose and uronic acids, i.e. sugars occurring in dietary fibre, were excreted in faeces. 3. Dietary fibre in wheat bran was rather resistant to fermentation; 63% was recovered in the faeces. Guar gum, on the other hand, was almost completely fermented, whereas 19 and 25% of the uronic acids in low and high methoxylated pectin respectively, were excreted in faeces. The various constituents of sugar-beet dietary fibre (approximately equal amounts of arabinose-based hemicellulose, pectin and non-starch glucan (cellulose)) showed quite variable availability for micro-organisms in that 6-12% of the arabinose, 17-25% of the uronic acids, and 52-58% of the cellulose were recovered in the faeces. 4. Faecal nitrogen excretion increased on addition of any one of the dietary fibre preparations studied, resulting in decreased true and apparent protein digestibility values. 5. The faecal dry weight increment was most pronounced when feeding bran and could then almost be accounted for by the remaining fibre and by protein. The less-prominent bulking effect of guar gum and pectins, that were much more extensively fermented, could be only partly explained by dietary fibre and protein. PMID:6282300

  2. Mortality experience of glass fibre workers.

    PubMed Central

    Shannon, H S; Hayes, M; Julian, J A; Muir, D C

    1984-01-01

    A historical prospective mortality study was conducted at an insulating wool plant in Ontario, Canada, on 2576 men who had worked for at least 90 days and were employed between 1955 and 1977. Eighty eight deaths were found in the 97.2% of men traced. Mortality was compared by the person-years method with that of the Ontario population. Measurements taken since 1977 show very low fibre concentrations. The overall standardised mortality ratio (SMR) was 78%, significantly below 100. Among plant only employees, seven deaths were attributed to lung cancer compared with 4.22 expected, a non-significant excess (SMR = 166; 95% confidence limits 67 to 342). No confirmed cases of mesothelioma were observed and no other disease was significantly increased in plant workers. PMID:6691934

  3. Multimode supercontinuum generation in chalcogenide glass fibres.

    PubMed

    Kubat, Irnis; Bang, Ole

    2016-02-01

    Mid-infrared supercontinuum generation is considered in chalcogenide fibres when taking into account both polarisations and the necessary higher order modes. In particular we focus on high pulse energy supercontinuum generation with long pump pulses. The modeling indicates that when only a single polarisation in the fundamental mode is considered the obtainable supercontinuum bandwidth is substantially exaggerated compared to when both polarisations are taken into account. Our modeling shows that if the pump pulse is short enough (≤ 10 ps) then higher order modes are not important because of temporal walk-off. In contrast long pump pulses (≥ 40 ps) will efficiently excite higher order modes through Raman scattering, which will deplete the fundamental mode of energy and limit the possibility of obtaining a broadband supercontinuum. PMID:26906826

  4. Electrostriction mechanism of Bragg grating formation in germanosilicate fibres

    SciTech Connect

    Neustruev, V B

    2001-11-30

    An electrostriction model is proposed for the photorefractive effect observed during the writing of Bragg gratings in germanosilicate fibres. Electrostriction is caused by a spatial charge grating formed upon the exposure to UV radiation. According to our estimate, the contribution of electrostriction to the photorefractive effect under real writing conditions is comparable with the contribution from colour centres and exceeds the contribution from the electrooptical effect by more than an order of magnitude. The electrostriction model explains the production of the IIA type Bragg grating in fibres with a high content of germanium in the core, as well as a number of effects that could not be explained earlier. (optical fibres)

  5. Novel shape memory alloy optical fibre connection method

    NASA Astrophysics Data System (ADS)

    Trouillard, G.; Zivojinovic, P.; Cerutti, R.; Godmaire, X. Pruneau; Weynant, E.

    2010-02-01

    In this paper, the capacity and quality of a shape memory alloy device is demonstrated for installation and connection of 125-μm to 1000-μm optical fibres. The new mechanical splice has the particularity of using a very simple tool for aligning and holding the cladding of fibres itself without the need of glue. Optimend main characteristics are its small dimensions (few millimetres), reusability, glueless, ruggedness, low temperature variation, heat dissipation and ease of use. These properties are very suitable for many optical fibre applications where both quick and reliable connections are desirable.

  6. All-fibre ytterbium laser tunable within 45 nm

    SciTech Connect

    Abdullina, S R; Babin, S A; Vlasov, A A; Kablukov, S I; Shelemba, I S; Kurkov, A S

    2007-12-31

    A tunable ytterbium-doped fibre laser is fabricated. The laser is tuned by using a tunable fibre Bragg grating (FBG) as a selecting intracavity element. The laser is tunable within 45 nm (from 1063 to 1108 nm) and emits {approx}6 W in the line of width {approx}0.15 nm, the output power and linewidth being virtually invariable within the tuning range. The method is proposed for synchronous tuning the highly reflecting and output FBGs, and a tunable ytterbium all-fibre laser is built. (lasers)

  7. Carbon fibre-reinforced silicon nitride composites by slurry infiltration

    SciTech Connect

    Grenet, C.; Plunkett, L.; Veyret, J.B.; Bullock, E.

    1995-12-01

    The present paper reports on the fabrication of long-carbon fibre reinforced silicon nitride matrix composites by liquid infiltration of an aqueous Si{sub 3}N{sub 4} slurry followed by hot-pressing. A methodology for the maximum volume and uniform infiltration of preforms has been developed by optimising slurry rheology and fibre wetting conditions. Fully infiltrated green forms of 55% theoretical density are achieved with some 40% volume fraction of fibres. The quality of the composites has been assessed by microstructural analysis and mechanical characterization.

  8. Respiratory monitoring using fibre long period grating sensors

    NASA Astrophysics Data System (ADS)

    Allsop, T.; Reeves, R.; Webb, D. J.; Bennion, I.; Earthrowl, T.; Jones, B.; Miller, M.

    2005-08-01

    We demonstrate the use of a series of in-line fibre long period grating curvature sensors on a garment, used to monitor the thoracic and abdominal volumetric tidal movements of a human subject. These results are used to obtain volumetric tidal changes of the human torso showing reasonable agreement with a spirometer used simultaneously to record the volume at the mouth during breathing. The curvature sensors are based upon long period gratings written in a progressive three layered fibre that are insensitive to refractive index changes. The sensor platform consists of the long period grating laid upon a carbon fibre ribbon, which is encapsulated in a low temperature curing silicone rubber.

  9. Organically Modified Silicas on Metal Nanowires

    PubMed Central

    2010-01-01

    Organically modified silica coatings were prepared on metal nanowires using a variety of silicon alkoxides with different functional groups (i.e., carboxyl groups, polyethylene oxide, cyano, dihydroimidazole, and hexyl linkers). Organically modified silicas were deposited onto the surface of 6-μm-long, ∼300-nm-wide, cylindrical metal nanowires in suspension by the hydrolysis and polycondensation of silicon alkoxides. Syntheses were performed at several ratios of tetraethoxysilane to an organically modified silicon alkoxide to incorporate desired functional groups into thin organosilica shells on the nanowires. These coatings were characterized using transmission electron microscopy, X-ray photoelectron spectroscopy, and infrared spectroscopy. All of the organically modified silicas prepared here were sufficiently porous to allow the removal of the metal nanowire cores by acid etching to form organically modified silica nanotubes. Additional functionality provided to the modified silicas as compared to unmodified silica prepared using only tetraethoxysilane precursors was demonstrated by chromate adsorption on imidazole-containing silicas and resistance to protein adsorption on polyethyleneoxide-containing silicas. Organically modified silica coatings on nanowires and other nano- and microparticles have potential application in fields such as biosensing or nanoscale therapeutics due to the enhanced properties of the silica coatings, for example, the prevention of biofouling. PMID:20715881

  10. Synthesis of mesoporous silica nanoparticles.

    PubMed

    Wu, Si-Han; Mou, Chung-Yuan; Lin, Hong-Ping

    2013-05-01

    Good control of the morphology, particle size, uniformity and dispersity of mesoporous silica nanoparticles (MSNs) is of increasing importance to their use in catalyst, adsorption, polymer filler, optical devices, bio-imaging, drug delivery, and biomedical applications. This review discusses different synthesis methodologies to prepare well-dispersed MSNs and hollow silica nanoparticles (HSNs) with tunable dimensions ranging from a few to hundreds of nanometers of different mesostructures. The methods include fast self-assembly, soft and hard templating, a modified Stöber method, dissolving-reconstruction and modified aerogel approaches. In practical applications, the MSNs prepared by these methods demonstrate good potential for use in high-performance catalysis, antireflection coating, transparent polymer-MSNs nanocomposites, drug-release and theranostic systems. PMID:23403864

  11. Gain functionalization of silica microresonators.

    PubMed

    Yang, Lan; Vahala, K J

    2003-04-15

    Erbium-doped solgel films are applied to the surface of silica microspheres to create low-threshold microactivity lasers. This gain functionalization can be applied by use of a number of different dopants, thereby extending the wavelength range of this class of device. Also, by varying the doping concentration and thickness of the applied solgel layer, one can vary the laser dynamics so that both continuous-wave and pulsating modes of operation are possible. PMID:12703910

  12. Preparation & characterization of SiO{sub 2} interface layer by dip coating technique on carbon fibre for C{sub f}/SiC composites

    SciTech Connect

    Kumar, Kundan; Jariwala, C. Pillai, R.; Chauhan, N.; Raole, P. M.

    2015-08-28

    Carbon fibres (C{sub f}) are one of the most important reinforced materials for ceramic matrix composites such as C{sub f} - SiC composites and they are generally sought for high temperature applications in as space application, nuclear reactor and automobile industries. But the major problem arise when C{sub f} reinforced composites exposed to high temperature in an oxidizing environment, C{sub f} react with oxygen and burnt away. In present work, we have studied the effect of silica (SiO{sub 2}) coating as a protective coating on C{sub f} for the C{sub f} / SiC composites. The silica solution prepared by the sol-gel process and coating on C{sub f} is done by dip coating technique with varying the withdrawing speed i.e. 2, 5, 8 mm/s with fixed dipping cycle (3 Nos.). The uniform silica coating on the C{sub f} is shown by the Scanning Electron Microscope (SEM) analysis. The tensile test shows the increase in tensile strength with respect to increase in withdrawing speed. The isothermal oxidation analysis confirmed enhancement of oxidation resistance of silica coated C{sub f} as compared tothe uncoated C{sub f}.

  13. Preparation & characterization of SiO2 interface layer by dip coating technique on carbon fibre for Cf/SiC composites

    NASA Astrophysics Data System (ADS)

    Kumar, Kundan; Jariwala, C.; Pillai, R.; Chauhan, N.; Raole, P. M.

    2015-08-01

    Carbon fibres (Cf) are one of the most important reinforced materials for ceramic matrix composites such as Cf - SiC composites and they are generally sought for high temperature applications in as space application, nuclear reactor and automobile industries. But the major problem arise when Cf reinforced composites exposed to high temperature in an oxidizing environment, Cf react with oxygen and burnt away. In present work, we have studied the effect of silica (SiO2) coating as a protective coating on Cf for the Cf / SiC composites. The silica solution prepared by the sol-gel process and coating on Cf is done by dip coating technique with varying the withdrawing speed i.e. 2, 5, 8 mm/s with fixed dipping cycle (3 Nos.). The uniform silica coating on the Cf is shown by the Scanning Electron Microscope (SEM) analysis. The tensile test shows the increase in tensile strength with respect to increase in withdrawing speed. The isothermal oxidation analysis confirmed enhancement of oxidation resistance of silica coated Cf as compared tothe uncoated Cf.

  14. Silica exposure and systemic vasculitis.

    PubMed Central

    Mulloy, Karen B

    2003-01-01

    Work in Department of Energy (DOE) facilities has exposed workers to multiple toxic agents leading to acute and chronic diseases. Many exposures were common to numerous work sites. Exposure to crystalline silica was primarily restricted to a few facilities. I present the case of a 63-year-old male who worked in DOE facilities for 30 years as a weapons testing technician. In addition to silica, other workplace exposures included beryllium, various solvents and heavy metals, depleted uranium, and ionizing radiation. In 1989 a painful macular skin lesion was biopsied and diagnosed as leukocytoclastic vasculitis. By 1992 he developed gross hematuria and dyspnea. Blood laboratory results revealed a serum creatinine concentration of 2.1 mg/dL, ethrythrocyte sedimentation rate of 61 mm/hr, negative cANCA (antineutrophil cytoplasmic antibody cytoplasmic pattern), positive pANCA (ANCA perinuclear pattern), and antiglomerular basement membrane negative. Renal biopsy showed proliferative (crescentric) and necrotizing glomerulonephritis. The patient's diagnoses included microscopic polyangiitis, systemic necrotizing vasculitis, leukocytoclastic vasculitis, and glomerulonephritis. Environmental triggers are thought to play a role in the development of an idiopathic expression of systemic autoimmune disease. Crystalline silica exposure has been linked to rheumatoid arthritis, scleroderma, systemic lupus erythematosus, rapidly progressive glomerulonephritis and some of the small vessel vasculitides. DOE workers are currently able to apply for compensation under the federal Energy Employees Occupational Illness Compensation Program (EEOICP). However, the only diseases covered by EEOICP are cancers related to radiation exposure, chronic beryllium disease, and chronic silicosis. PMID:14644669

  15. Effects of high intensity canoeing training on fibre area and fibre type in the latissimus dorsi muscle.

    PubMed Central

    Baker, S J; Hardy, L

    1989-01-01

    A high intensity short duration exercise training programme was undertaken by nine subjects on three occasions each week for nine weeks. Muscle samples from the latissimus dorsi were taken by needle biopsy, at rest, before and after training. The results revealed that there was no change in either Type I or Type II muscle fibre distribution following training. Type I fibre area did not alter significantly as a result of the training stress. Mean cross-sectional area of Type II fibres was 82 per cent greater post-training than pre-training. Images Figure 1 Figure 2 PMID:2730995

  16. Adaptive dynamic FBG interrogation utilising erbium-doped fibre

    NASA Astrophysics Data System (ADS)

    John, R. N.; Read, I.; MacPherson, W. N.

    2013-04-01

    A dynamic fibre Bragg grating interrogation scheme is investigated using two-wave mixing in erbium-doped fibre, capable of adapting to quasistatic strain and temperature drifts. An interference pattern set up in the erbium-doped fibre creates, due to the photorefractive effect, a dynamic grating capable of wavelength demodulating the FBG signal. The presence of a dynamic grating was verified and then dynamic strain signals from a fibre stretcher were measured. The adaptive nature of the technique was successfully demonstrated by heating the FBG while it underwent dynamic straining leading to detection unlike an alternative arrayed waveguide grating system which simultaneously failed detection. Two gratings were then wavelength division multiplexed with the signal grating receiving approximately 30dB greater signal showing that there was little cross talk in the system.

  17. Dynamic fracture behaviour in fibre-reinforced cementitious composites

    NASA Astrophysics Data System (ADS)

    Yu, Rena C.; Cifuentes, Héctor; Rivero, Ignacio; Ruiz, Gonzalo; Zhang, Xiaoxin

    2016-08-01

    The object of this work is to simulate the dynamic fracture propagation in fibre-reinforced cementitious composites, in particular, in steel fibre reinforced concrete (SFRC). Beams loaded in a three-point bend configuration through a drop-weight impact device are considered. A single cohesive crack is assumed to propagate at the middle section; the opening of this crack is governed by a rate-dependent cohesive law; the fibres around the fracture plane are explicitly represented through truss elements. The fibre pull-out behaviour is depicted by an equivalent constitutive law, which is obtained from an analytical load-slip curve. The obtained load-displacement curves and crack propagation velocities are compared with their experimental counterparts. The good agreement with experimental data testifies to the feasibility of the proposed methodology and paves the way to its application in a multi-scale framework.

  18. Phase delay of polarisation modes in elastically twisted spun fibres

    SciTech Connect

    Morshnev, Sergey K; Chamorovsky, Yury K; Vorob'ev, Igor' L

    2011-05-31

    The evolution of the phase delay between linearly polarised orthogonal modes in a spun fibre elastically twisted around its axis has been studied experimentally and theoretically using a model for a helical structure of the built-in linear birefringence axes. The phase delay is a sinusoidal function of elastic twist angle, with an amplitude and period dependent on fibre parameters: spin pitch and built-in linear birefringence beat length. It is shown that, at a known spin pitch, phase delay versus elastic twist angle data can be used to determine the beat length of built-in linear birefringence in the range 0.01 to 100 mm. The theoretical analysis results are supported by experimental data for conventional and microstructured spun fibres. (fibre optics)

  19. The Formation and Binding of Gold Nanoparticles onto Wool Fibres

    SciTech Connect

    Johnston, James H.; Burridge, Kerstin A.; Kelly, Fern M.

    2009-07-23

    This paper presents the novel use of nanosize gold with different plasmon resonance colours, as stable colourfast colourants on wool fibres for use in high quality fabrics and textiles. The gold nanoparticles are synthesised by the controlled reduction of Au{sup 3+} in the AuCl{sub 4}{sup -} complex to Au{sup 0} onto the surface of the wool where they attach to the S in the cystine amino acids in wool keratin proteins. Scanning electronmicroscopy shows the nanoparticles are present on the cuticles of the fibre surface and are concentrated at the edges of these cuticles. EDS analysis shows a strong correlation of Au with S and X-ray photoelectron spectroscopy suggests Au-S bond formation. Hence the nanogold colourants are chemically bound to the wool fibre surface and do not fade as traditional organic dyes do. A range of coloured fibres have been produced.

  20. Studies of avalanche photodiodes for scintillating fibre tracking readout

    SciTech Connect

    Fenker, H; Thomas, J

    1993-01-01

    Avalanche Photodiodes (APDs) operating in ``Geiger Mode`` have been studied in a fibre tracking readout environment. A fast recharge circuit has been developed for high rate data taking, and results obtained from a model fibre tracker in the test beam at Brookhaven National Laboratory are presented. A high rate calibrated light source has been developed using a commercially available laser diode and has been used to measure the efficiency of the devices. The transmission of the light from a 1mm fibre onto a 0.5mm diameter APD surface has been identified as the main problem in the use of these particular devices for scintillating fibre tracking in the Superconducting Supercollider environment. Solutions to this problem are proposed.

  1. Applications of optical fibres at Lublin University of Technology

    NASA Astrophysics Data System (ADS)

    Kacejko, Piotr; Wójcik, Waldemar

    2015-12-01

    The article contains a brief history and present days of research and education in application of optical fibres at Lublin University of Technology. It also presents the potential of research groups working at the University.

  2. Meniscus on a shaped fibre: singularities and hodograph formulation

    PubMed Central

    Alimov, Mars M.; Kornev, Konstantin G.

    2014-01-01

    Using the method of matched asymptotic expansions, the problem of the capillary rise of a meniscus on the complex-shaped fibres was reduced to a nonlinear problem of determination of a minimal surface. This surface has to satisfy a special boundary condition at infinity. The proposed formulation allows one to interpret the meniscus problem as a problem of flow of a fictitious non-Newtonian fluid through a porous medium. As an example, the shape of a meniscus on a fibre of an oval cross section was analysed employing Chaplygin's hodograph transformation. It was discovered that the contact line may form singularities even if the fibre has a smooth profile: this statement was illustrated with an oval fibre profile having infinite curvature at two endpoints. PMID:25104910

  3. Exploiting multimode waveguides for pure fibre-based imaging

    PubMed Central

    Čižmár, Tomáš; Dholakia, Kishan

    2012-01-01

    There has been an immense drive in modern microscopy towards miniaturization and fibre-based technology. This has been necessitated by the need to access hostile or difficult environments in situ and in vivo. Strategies to date have included the use of specialist fibres and miniaturized scanning systems accompanied by ingenious microfabricated lenses. Here we present a novel approach for this field by utilizing disordered light within a standard multimode optical fibre for lensless microscopy and optical mode conversion. We demonstrate the modalities of bright- and dark-field imaging and scanning fluorescence microscopy at acquisition rates that allow observation of dynamic processes such as Brownian motion of mesoscopic particles. Furthermore, we show how such control can realize a new form of mode converter and generate various types of advanced light fields such as propagation-invariant beams and optical vortices. These may be useful for future fibre-based implementations of super-resolution or light-sheet microscopy. PMID:22929784

  4. The role of dietary fibre in inflammatory bowel disease

    PubMed Central

    Banaszkiewicz, Aleksandra; Albrecht, Piotr

    2015-01-01

    The aetiology of inflammatory bowel diseases (IBD), which are primarily Crohn's disease and ulcerative colitis, still remains unclear, while the incidence of IBD is constantly increasing, especially in the industrialised countries. Among genetic, environmental, and immunological factors, changes in the composition of the intestinal microflora and diet are indicated as very important in initiating and sustaining inflammation in patients with IBD. Above all nutrients dietary fibre is an especially important component of diet in the context of IBD. A potentially protective effect of high-fibre diet on intestinal disorders was described as early as in 1973. Several trials performed in animal models of IBD and human studies have reported that supplementation of some types of dietary fibre can prolong remission and reduce lesions of the intestinal mucosa during the course of the disease. This paper presents the current state of knowledge on the effects of dietary fibre in IBD. PMID:26516378

  5. Graphene chiral liquid crystals and macroscopic assembled fibres

    PubMed Central

    Xu, Zhen; Gao, Chao

    2011-01-01

    Chirality and liquid crystals are both widely expressed in nature and biology. Helical assembly of mesophasic molecules and colloids may produce intriguing chiral liquid crystals. To date, chiral liquid crystals of 2D colloids have not been explored. As a typical 2D colloid, graphene is now receiving unprecedented attention. However, making macroscopic graphene fibres is hindered by the poor dispersibility of graphene and by the lack of an assembly method. Here we report that soluble, chemically oxidized graphene or graphene oxide sheets can form chiral liquid crystals in a twist-grain-boundary phase-like model with simultaneous lamellar ordering and long-range helical frustrations. Aqueous graphene oxide liquid crystals were continuously spun into metres of macroscopic graphene oxide fibres; subsequent chemical reduction gave the first macroscopic neat graphene fibres with high conductivity and good mechanical performance. The flexible, strong graphene fibres were knitted into designed patterns and into directionally conductive textiles. PMID:22146390

  6. Performance of Straight Steel Fibres Reinforced Alkali Activated Concrete

    NASA Astrophysics Data System (ADS)

    Faris, Meor Ahmad; Bakri Abdullah, Mohd Mustafa Al; Nizar Ismail, Khairul; Muniandy, Ratnasamy; Putra Jaya, Ramadhansyah

    2016-06-01

    This paper focus on the performance of alkali activated concrete produced by using fly ash activated by sodium silicate and sodium hydroxide solutions. These alkali activated concrete were reinforced with straight steel fibres with different weight percentage starting from 0 % up to 5 %. Chemical composition of raw material in the production alkali activated concrete which is fly ash was first identified by using X-ray fluorescence. Results reveal there have an effect of straight steel fibres inclusion to the alkali activated concrete. Highest compressive strength of alkali activated concrete which is 67.72 MPa was obtained when 3 % of straight fibres were added. As well as flexural strength, highest flexural strength which is 6.78 MPa was obtained at 3 % of straight steel fibres inclusions.

  7. Nondestructive identification of engineering properties of metal fibre composites

    NASA Astrophysics Data System (ADS)

    Vala, J.; Horák, M.

    2012-09-01

    Macroscopic homogeneity of metal fibre composites, namely those used for building structures, characterized by constant volume fraction of randomly oriented fibre particles, as well as their isotropy, or, alternatively, prescribed orientation of fibres, determines their mechanical, thermal, etc. properties, consequently their long-time behaviour, reliability and range of user applications. Destructive tests are available under laboratory conditions, but frequently impossible in situ, thus the development of reliable nondestructive approaches is required. This paper presents the physical and mathematical background of two classes of such tests, based i) on the planar radiographic images, analyzed with help of the fast Fourier transform, ii) on the magnetic properties of materials, using the Hall effect and properties of solutions of the Laplace equation. Practical results with fibre concrete samples from Brno University of Technology demonstrate the advantages and drawbacks of both approaches and sketch the possibilities of their future generalization.

  8. Hierarchical scaling law for the strength of composite fibre bundles

    NASA Astrophysics Data System (ADS)

    Pimenta, Soraia; Pinho, Silvestre T.

    2013-06-01

    This paper presents an analytical model for size effects on the longitudinal tensile strength of composite fibre bundles. The strength of individual fibres is modelled by a Weibull distribution, while the matrix (or fibre-matrix interface) is represented through a perfectly plastic shear-lag model. A probabilistic analysis of the failure process in hierarchical bundles (bundles of bundles) is performed, so that a scaling law relating the strength distributions and characteristic lengths of consecutive bundle levels is derived. An efficient numerical scheme (based on asymptotic limits) is proposed, hence coupon-sized bundle strength distributions are obtained almost instantaneously. Parametric studies show that both fibre and matrix properties are critical for bundle strength; model predictions at different scales are validated against experimental results available in the literature.

  9. Dietary fibre and colon cancer: epidemiologic and experimental evidence.

    PubMed Central

    Reddy, B S

    1980-01-01

    Epidemiologic studies have identified two dietary factors, a relatively high intake of fat and a relatively low intake of fibre, that are associated with colon cancer in humans. However, a recent study has shown a low risk of large bowel cancer in a rural Finnish population with a high dietary intake of fat, but also a high intake of fibre. Observations in humans and studies in animals have indicated that dietary fibre may protect against colon carcinogenesis by binding bile acids in the intestinal tract, by a direct effect on the colonic mucosa and by an indirect effect on the metabolism of carcinogens. The strength of protection varies with the type of fibre. PMID:6254626

  10. Non-occupational exposure to silica dust

    PubMed Central

    Bhagia, L. J.

    2012-01-01

    Occupational exposure to silica occurs at workplaces in factories like quartz crushing facilities (silica flour milling), agate, ceramic, slate pencil, glass, stone quarries and mines, etc., Non-occupational exposure to silica dust can be from industrial sources in the vicinity of the industry as well as non-industrial sources. Recently, public concern regarding non-occupational or ambient exposure to crystalline silica has emerged making it important to gather information available on non-occupational exposures to silica dust and non-occupational silicosis. This paper reviews various non-occupational exposures reported in literature including some studies by the author. Methodology used in assessment of non-occupational exposures, standards for non-occupational exposures to silica dust and indirect estimation of cumulative risk % are also discussed. PMID:23776316

  11. Silica Extraction at Mammoth Lakes, California

    SciTech Connect

    Bourcier, W; Ralph, W; Johnson, M; Bruton, C; Gutierrez, P

    2006-06-07

    The purpose of this project is to develop a cost-effective method to extract marketable silica (SiO{sub 2}) from fluids at the Mammoth Lakes, California geothermal power plant. Silica provides an additional revenue source for the geothermal power industry and therefore lowers the costs of geothermal power production. The use of this type of ''solution mining'' to extract resources eliminates the need for acquiring these resources through energy intensive and environmentally damaging mining technologies. We have demonstrated that both precipitated and colloidal silica can be produced from the geothermal fluids at Mammoth Lakes by first concentrating the silica to over 600 ppm using reverse osmosis (RO). The RO permeate can be used in evaporative cooling at the plant; the RO concentrate is used for silica and potentially other resource extraction (Li, Cs, Rb). Preliminary results suggest that silica recovery at Mammoth Lakes could reduce the cost of geothermal electricity production by 1.0 cents/kWh.

  12. Characterization of diatomaceous silica by Raman spectroscopy.

    PubMed

    Yuan, P; He, H P; Wu, D Q; Wang, D Q; Chen, L J

    2004-10-01

    The network characteristic of a selection of diatomaceous silica derived from China has been investigated using Raman spectroscopy. Before any thermal treatment of the sample, two prominent bands of 607 and circa 493 cm(-1) are resolved in the Raman spectra of diatomaceous silica, corresponding to the (SiO)3-ring breathing mode of D2-line and the O3SiOH tetrahedral vibration mode of D1-line, respectively. This is more similar to the pyrogenic silica rather than the silica gel. For the latter, to obtain a (SiO)3-ring, the sample must be heated between 250 and 450 degrees C. Significant difference is also found between the diatomaceous silica and other natural silicas, e.g. in the Raman spectra of sedimentary and volcanic opals, neither D1 nor D2 band is detected in previous reports. PMID:15350933

  13. Characterization of diatomaceous silica by Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Yuan, P.; He, H. P.; Wu, D. Q.; Wang, D. Q.; Chen, L. J.

    2004-10-01

    The network characteristic of a selection of diatomaceous silica derived from China has been investigated using Raman spectroscopy. Before any thermal treatment of the sample, two prominent bands of 607 and circa 493 cm -1 are resolved in the Raman spectra of diatomaceous silica, corresponding to the (SiO) 3-ring breathing mode of D 2-line and the O 3SiOH tetrahedral vibration mode of D 1-line, respectively. This is more similar to the pyrogenic silica rather than the silica gel. For the latter, to obtain a (SiO) 3-ring, the sample must be heated between 250 and 450 °C. Significant difference is also found between the diatomaceous silica and other natural silicas, e.g. in the Raman spectra of sedimentary and volcanic opals, neither D 1 nor D 2 band is detected in previous reports.

  14. Highly birefringent low-mode-asymmetry microstructured optical fibres

    SciTech Connect

    Denisov, A N; Levchenko, A E; Semenov, S L; Dianov, Evgenii M

    2011-03-31

    A novel birefringent microstructured fibre (BMF) design is proposed, and its birefringence and dispersion characteristics are analysed using the finite element method. The results indicate that the proposed BMF design ensures high birefringence ({approx}5x10{sup -3}) at a low mode asymmetry. At a certain core ellipticity, the BMF configurations considered may have equal mode field sizes along two orthogonal axes. (fibre optics)

  15. Measurement of magnetic field using Rayleigh backscattering in optical fibres

    SciTech Connect

    Wuilpart, M.; Caucheteur, C.; Goussarov, A.; Aerssens, M.; Massaut, V.; Megret, P.

    2011-07-01

    In this paper, we investigate the use of optical reflectometry in optical fibres for the measurement of magnetic field. The dedicated application concerns the measurement of plasma current in the fusion reactor. The measurement is based on the rotation of the polarization state of the Rayleigh backscattered signal when an optical pulse is launched in the fibre. Particular care has been undertaken to evaluate the impact of linear birefringence on the measurement performance. (authors)

  16. IR luminescence in bismuth-doped germanate glasses and fibres

    SciTech Connect

    Pynenkov, A A; Firstov, Sergei V; Panov, A A; Firstova, E G; Nishchev, K N; Bufetov, Igor' A; Dianov, Evgenii M

    2013-02-28

    We have studied the optical properties of lightly bismuth doped ({<=}0.002 mol %) germanate glasses prepared in an alumina crucible. The glasses are shown to contain bismuth-related active centres that have been identified previously only in bismuth-doped fibres produced by MCVD. With increasing bismuth concentration in the glasses, their luminescence spectra change markedly, which is attributable to interaction between individual bismuth centres. (optical fibres)

  17. SOLITONS: Nonreciprocal dynamics of pulses in a nonlinear inhomogeneous fibre

    NASA Astrophysics Data System (ADS)

    Adamova, M. S.; Zolotovskii, Igor'O.; Sementsov, Dmitrii I.

    2007-08-01

    The conditions, under which the nonreciprocity of the frequency modulation rate and pulse duration as well as the spectral nonreciprocity in fibres with different types of inhomogeneity of nonlinearity and group-velocity dispersion appear, are studied for the Gaussian and hyperbolic secant frequency-modulated pulses. Strong compression nonreciprocity is found in fibres with an alternating group-velocity dispersion periodically changing over its length.

  18. Sealed silica pressure ampoules for crystal growth

    NASA Technical Reports Server (NTRS)

    Holland, L. R.

    1984-01-01

    The properties of vitreous silica and the mechanics of thick walled pressure vessels are reviewed with regard to the construction of sealed silica crucibles such as are used in the growth of mercury-cadmium telluride crystals. Data from destructive rupture tests are reported, failure modes discussed, and recommendations for design given. Ordinary commercial clear vitreous silica from flame fused quartz can withstand a surface stress of 20 MPa or more in this application.

  19. Process for preparing polymer reinforced silica aerogels

    NASA Technical Reports Server (NTRS)

    Meador, Mary Ann B. (Inventor); Capadona, Lynn A. (Inventor)

    2011-01-01

    Process for preparing polymer-reinforced silica aerogels which comprises a one-pot reaction of at least one alkoxy silane in the presence of effective amounts of a polymer precursor to obtain a silica reaction product, the reaction product is gelled and subsequently subjected to conditions that promotes polymerization of the precursor and then supercritically dried to obtain the polymer-reinforced monolithic silica aerogels.

  20. Mesoporous Silica: A Suitable Adsorbent for Amines

    PubMed Central

    2009-01-01

    Mesoporous silica with KIT-6 structure was investigated as a preconcentrating material in chromatographic systems for ammonia and trimethylamine. Its adsorption capacity was compared to that of existing commercial materials, showing its increased adsorption power. In addition, KIT-6 mesoporous silica efficiently adsorbs both gases, while none of the employed commercial adsorbents did. This means that KIT-6 Mesoporous silica may be a good choice for integrated chromatography/gas sensing micro-devices. PMID:20628459

  1. A Pd/silica composite with highly uniform Pd nanoparticles on silica lamella via layered silicate

    NASA Astrophysics Data System (ADS)

    Hao, Jing; Cui, Zhi-Min; Cao, Chang-Yan; Song, Weiguo

    2016-08-01

    Pd nanoparticles was loaded on silica lamella via layered silicate through a simple ion-exchange and in situ reduction method. The obtained Pd/silica composite has Pd nanoparticles with highly uniform size dispersed well on the silica lamella. The Pd/silica composite is active and recoverable catalyst for the hydrogenation reaction and the reaction can be completed in a short time of 2 h at room temperature and 1 atm H2 pressure.

  2. Dietary fibre as an important constituent of the diet.

    PubMed

    Maćkowiak, Kalina; Torlińska-Walkowiak, Natalia; Torlińska, Barbara

    2016-01-01

    The intake of fibre in the diet of a child or an adult, through various foods (such as wholegrain foods, nuts, fruits and vegetables), plays an important role in reducing the risk and lowering the incidence of numerous diseases. The interest of researchers and consumers in the role of diet in the prevention or treatment of many illnesses, and maintaining the general and oral health, has been growing lately. The aim of our study was to underline the role of dietary fibre through its effects on many aspects of the human body and metabolism. Evidence has been found that dietary fibre from whole foods or supplements may reduce the risk of cardiovascular disease by improving serum lipids and reducing serum total and low-density lipoprotein (LDL) cholesterol concentrations in adults and children. Increased fibre content decreases the glycaemic index of foods, which leads to a significant improvement in glycaemic response. High fibre intake is associated with reduced risk of colorectal and breast cancer. In contemporary children, the reluctance to chew raw, hard plant foods may result in a risk of malocclusion and a lack of tooth wear, which cause the need for orthodontic intervention. Fibre consumption is associated with high nutritional value and antioxidant status of the diet, enhancing the effects on human health. PMID:26943307

  3. Dual morphology (fibres and particles) cellulosic filler for WPC materials

    NASA Astrophysics Data System (ADS)

    Valente, Marco; Tirillò, Jacopo; Quitadamo, Alessia; Santulli, Carlo

    2016-05-01

    Wood-plastic composites (WPC) were fabricated by using a polyethylene (PE) matrix and filling it with wood flour in the amount of 30 wt.%, and compared with the same composites with further amount of 10 wt.% of cellulosic recycled fibres added. The materials were produced by turbomixing and subsequent moulding under pressure. Mechanical properties of both WPC and WPC with cellulosic recycled fibres were evaluated through mechanical and physical-chemical tests. Tensile tests clarified that a moderate reduction is strength is observed with the bare introduction of wood flour with respect to the neat PE matrix, whilst some recovery is offered by the addition of recycled cellulose fibres. Even more promisingly, the elastic modulus of PE matrix is substantially improved by the addition of wood flour (around 8% on average) and much more so with the further addition of recycled cellulose (around 20% on average). The fracture surfaces from the tensile test were analysed by scanning electron microscope (SEM) indicating a reduction in microporosity as an effect of added cellulose. The water absorption test and the hardness measure (Shore D) were also performed. SEM analysis underlined the weak interface between both wood particle and cellulosic recycled fibres and matrix. The water absorption test showed a higher mass variation for pure WPC than WPC with cellulosic recycled fibres. The hardness measurement showed that the presence of cellulosic recycled fibres improves both superficial hardness of the composite and temperature resistance.

  4. Seven-core active fibre for application in telecommunication satellites

    NASA Astrophysics Data System (ADS)

    Filipowicz, Marta; Napierała, Marek; Murawski, Michał; Ostrowski, Łukasz; Szostkiewicz, Łukasz; Szymański, Michał; Tenderenda, Tadeusz; Anders, Krzysztof; Piramidowicz, Ryszard; Wójcik, Grzegorz; Makara, Mariusz; Poturaj, Krzysztof; Mergo, Paweł; Nasiłowski, Tomasz

    2015-12-01

    The use of optical elements and other photonic components makes it possible to overcome telecommunication satellite's bottleneck problems such as size and weight reduction. Despite the unquestionable potential of such elements, nowadays they are not widely used in systems operating in space. This is due to many factors, including the fact that space radiation has disruptive influence on optical fibre. Namely it introduces additional radiation induced attenuation (RIA) that significantly lowers efficiency of optical fibre based systems. However, there is a possibility to produce radiation-hardened (rad-hard) components. One of them is seven core erbium-doped active fibre (MC-EDF) for fibre amplifiers in satellites that we have been developing. In this paper we present a detailed description of seven core structure design as well as experimental results. We report that average gain of 20 dB in C-band with noise figure of 5.8 dB was obtained. We also confirmed that low crosstalk value for a multicore fibre amplifier based on our fibre can be achieved.

  5. Nonlinear fibre-optic devices pumped by semiconductor disk lasers

    SciTech Connect

    Chamorovskiy, A Yu; Okhotnikov, Oleg G

    2012-11-30

    Semiconductor disk lasers offer a unique combination of characteristics that are particularly attractive for pumping Raman lasers and amplifiers. The advantages of disk lasers include a low relative noise intensity (-150 dB Hz{sup -1}), scalable (on the order of several watts) output power, and nearly diffraction-limited beam quality resulting in a high ({approx}70 % - 90 %) coupling efficiency into a single-mode fibre. Using this technology, low-noise fibre Raman amplifiers operating at 1.3 {mu}m in co-propagation configuration are developed. A hybrid Raman-bismuth doped fibre amplifier is proposed to further increase the pump conversion efficiency. The possibility of fabricating mode-locked picosecond fibre lasers operating under both normal and anomalous dispersion is shown experimentally. We demonstrate the operation of 1.38-{mu}m and 1.6-{mu}m passively mode-locked Raman fibre lasers pumped by 1.29-{mu}m and 1.48-{mu}m semiconductor disk lasers and producing 1.97- and 2.7-ps pulses, respectively. Using a picosecond semiconductor disk laser amplified with an ytterbium-erbium fibre amplifier, the supercontinuum generation spanning from 1.35 {mu}m to 2 {mu}m is achieved with an average power of 3.5 W. (invited paper)

  6. Novel technique for solar power illumination using plastic optical fibres

    NASA Astrophysics Data System (ADS)

    Munisami, J.; Kalymnios, D.

    2008-09-01

    Plastic Optical Fibres (POF) were developed almost 3 decades ago. They are mainly used for short haul data communications (up to 1 km with data rates up to 1 Gbps). Over the years, POF has found applications in many other areas including solar energy transport for illumination. In such an application, light is collected from the sun and is directed into a space which needs to be illuminated. The use of fibres and more specifically POF, in daylighting systems, started only a few years ago. Several approaches have been investigated and we have seen the development of a few commercial products. The market however, has not really taken off for these technologies simply because of their enormous price tags. It is important to note that the use of POF in these designs has been limited to the function of POF as the transmission medium only. We propose a novel solar illumination technique using POF as both the light collecting/concentrating mechanism and the transmission medium. By modifying the structure of the fibre, solar light can be directed into the fibre by using an analogous process to fibre side emission but, in the reverse. We shall report on the solar light capturing efficiency of POF as modified by several types of external imperfections introduced onto the fibre. One major advantage of our proposed approach lies in the fact that we aim to eliminate at least one of the two axes of sun tracking that is currently used in existing solar illumination systems.

  7. Plantain fibre bundles isolated from Colombian agro-industrial residues.

    PubMed

    Gañán, Piedad; Zuluaga, Robin; Restrepo, Adriana; Labidi, Jalel; Mondragon, Iñaki

    2008-02-01

    Comestible fruit production from Musaceas plants is an important economical activity in developing countries like Colombia. However, it generates a large amount of agro-industrial residues. Some of them are a potential resource of natural fibres, which can be used as reinforcement for composite materials. In this work, a series of commercial plantain (Musa AAB, cv "Dominico Harton") fibre bundles extracted from pseudostem, leaf sheath and rachis agricultural wastes were analyzed. Mechanical decortication and biological retting processes were used during fiber extraction. No significant differences in composition of vascular bundles were observed for both extraction processes. Gross morphological characteristics and mechanical behavior have been evaluated. Conducting tissues with spiral-like arrangement are observed attached to fibre bundles. This fact suggests a big amount of these tissues in commercial plantain plants. Both used extraction methods are not enough to remove them. Pseudostem fibre bundles have higher specific strength and modulus and lower strain at break than leaf sheath and rachis fibre bundles, having values comparable to other lignocellulosic fibres bundles. PMID:17350832

  8. Endogenously triggered electrospun fibres for tailored and controlled antibiotic release.

    PubMed

    Dave, Rachna; Jayaraj, Prithi; Ajikumar, Puthuparampil K; Joshi, Hiren; Mathews, Tom; Venugopalan, Vayalam P

    2013-01-01

    The study was aimed at assessing the potential of enzyme-embedded antibiotic-releasing polycaprolactone (PCL)-based electrospun fibres for tunable drug delivery. This was attempted by incorporation of gentamicin sulphate (GS) in the biocompatible polymer (PCL) matrix, with the degradation of the matrix being ensured by co-impregnating a polymer-degrading enzyme (lipase). Single phase solutions were obtained by hydrophobic ion pairing of GS and surfactant coating of lipase with an anionic surfactant, docusate sodium salt Aerosol OT (AOT). By electrospinning the solution, we could produce PCL fibres containing 11% (w/w) GS-AOT and 28 U (w/w) lipase-AOT. However, sustained release of GS was not obtained. FESEM analysis showed that the fibres did not undergo the expected degradation. Subsequent experiments with unmodified lipase gave satisfactory results; the polymer underwent degradation displaying characteristic perforations in the fibres, suggestive of 'endo-attack'. By modulating the concentrations of lipase (1 to 28 U, w/w), we could obtain GS release rates that varied from 0.53 to 32 mg/ml/d. Accordingly, the lifetime of the fibres could be tuned (10 h to 25 days). The fibres showed excellent antibacterial activity against Staphylococcus aureus throughout their lifetime. PMID:23796032

  9. Preparation of reactive fibre interfaces using multifunctional cellulose derivatives.

    PubMed

    Vega, Beatriz; Wondraczek, Holger; Bretschneider, Leonore; Näreoja, Tuomas; Fardim, Pedro; Heinze, Thomas

    2015-11-01

    Cellulose fibres have poor reactivity and limited potential for surface engineering with advanced chemical functionalization in water. In this work, cellulose fibres were decorated with azide functions by charge-directed self-assembly of a novel water-soluble multifunctional cellulose derivative yielding reactive fibres. Propargylamine and 1-ethynylpyrene were utilized as a proof of concept that alkyne molecules may react with the azide functions of the reactive fibres via copper(I)-catalyzed azide-alkyne Huisgen cycloaddition (CuAAc) reaction in mild conditions. Chemical characterization of the fibres was carried out using classical techniques such as Raman-, fluorescence-, and UV-vis spectroscopy. Among other techniques, time-of-flight secondary ion mass spectrometry (ToF-SIMS), X-ray spectroscopy (XPS), two-photon microscopy (TPM), and inductively coupled plasma mass spectrometry (ICP-MS) were useful tools for additional characterization of the fibres decorated with amino- or photoactive groups. The information gathered in this work might contribute to the basis for the preparation of reactive cellulose-based interfaces with potential application in CuAAc reactions. PMID:26256349

  10. Fire Retardancy of Natural Fibre Reinforced Sheet Moulding Compound

    NASA Astrophysics Data System (ADS)

    Hapuarachchi, T. D.; Ren, G.; Fan, M.; Hogg, P. J.; Peijs, T.

    2007-07-01

    Due to environmental awareness and economical considerations, natural fibre reinforced polymer composites seem to present a viable alternative to synthetic fibre reinforced polymer composites such as glass fibres. This is a feasibility study to asses the potential application of natural fibre reinforced sheet moulding compound materials (NF-SMC) for the use in building applications, with particular emphases to their reaction to fire. The reinforcing fibres in this study were industrial hemp fibres. The cone calorimeter which asses the fire hazard of materials by Heat Release Rate (HRR) was used, radiant heat fluxes of 25 and 50 kW/m2 were utilised to simulate an ignition source and fully developed room fire conditions respectively. The results acquired here demonstrate that the NF-SMC can compete with current building materials in terms of their fire behaviour. The peak heat release value for the fire retardant (FR) NF-SMC was 176 kW/m2 conversely for a non-FR NF-SMC was 361 kW/m2.

  11. Investigation of Mechanical Properties of Steel Fibre- Reinforced Concrete

    NASA Astrophysics Data System (ADS)

    Ryabchikov, A.; Tamme, V.; Laurson, M.

    2015-11-01

    Steel fibre-reinforced concrete (SFRC) is widely used in the structural elements of buildings: industrial floors, slabs, walls, foundation, etc. When a load is applied to a fibre- reinforced composite consisting of a low-modulus matrix reinforced with high-strength, high- modulus fibres, the plastic flow of the matrix under stress transfers the load to the fibre; this results in high-strength, high-modulus material which determines the stiffness and stress of the composite. In this study the equivalent flexural strength, equivalent flexural ratio Re,3 and the compressing strength of SFRC are investigated. Notched test specimens with five different dosages of steel fibres (20, 25, 30, 35, 40 kg/m3) were prepared using industrial concrete. Determination of flexural tension strength was carried out according to the EU norm EVS-EN 14651:2005+A1:2007. The equivalent flexural strength and subsequent equivalent flexural ratio Re,3 of SFRC with a dosage of 20, 25, 30, 35 kg/m3 similar to their average values and with a dosage of 40 kg/m3 were 31% higher than their average values. The compressive strength of the steel fibre-reinforced concrete was slightly higher compared to plain concrete, except specimens with the dosage of 40 kg/m3 where the increase was 30%.

  12. Nano zinc oxide-sodium alginate antibacterial cellulose fibres.

    PubMed

    Varaprasad, Kokkarachedu; Raghavendra, Gownolla Malegowd; Jayaramudu, Tippabattini; Seo, Jongchul

    2016-01-01

    In the present study, antibacterial cellulose fibres were successfully fabricated by a simple and cost-effective procedure by utilizing nano zinc oxide. The possible nano zinc oxide was successfully synthesized by precipitation technique and then impregnated effectively over cellulose fibres through sodium alginate matrix. XRD analysis revealed the 'rod-like' shape alignment of zinc oxide with an interplanar d-spacing of 0.246nm corresponding to the (101) planes of the hexagonal wurtzite structure. TEM analysis confirmed the nano dimension of the synthesized zinc oxide nanoparticles. The presence of nano zinc oxide over cellulose fibres was evident from the SEM-EDS experiments. FTIR and TGA studies exhibited their effective bonding interaction. The tensile stress-strain curves data indicated the feasibility of the fabricated fibres for longer duration utility without any significant damage or breakage. The antibacterial studies against Escherichia coli revealed the excellent bacterial devastation property. Further, it was observed that when all the parameters remained constant, the variation of sodium alginate concentration showed impact in devastating the E. coli. In overall, the fabricated nano zinc oxide-sodium alginate cellulose fibres can be effectively utilized as antibacterial fibres for biomedical applications. PMID:26453887

  13. Raman studies of gluten proteins aggregation induced by dietary fibres.

    PubMed

    Nawrocka, Agnieszka; Szymańska-Chargot, Monika; Miś, Antoni; Kowalski, Radosław; Gruszecki, Wiesław I

    2016-03-01

    Interactions between gluten proteins and dietary fibre preparations are crucial in the baking industry. The addition of dietary fibre to bread causes significant reduction in its quality which is influenced by changes in the structure of gluten proteins. Fourier transform Raman spectroscopy was applied to determine changes in the structure of gluten proteins modified by seven dietary fibres. The commercially available gluten proteins without starch were mixed with the fibres in three concentrations: 3%, 6% and 9%. The obtained results showed that all fibres, regardless of their origin, caused the same kind of changes i.e. decrease in the α-helix content with a simultaneous increase in the content of antiparallel-β-sheet. The results indicated that presence of cellulose was the probable cause of these changes, and lead to aggregation or abnormal folding of the gluten proteins. Other changes observed in the gluten structure concerning β-structures, conformation of disulphide bridges, and aromatic amino acid environment, depended on the fibres chemical composition. PMID:26471530

  14. Structural study on methacrylamide-grafted Tussah silk fibroin fibres.

    PubMed

    Pavoni, Eleonora; Tozzi, Silvia; Tsukada, Masuhiro; Taddei, Paola

    2016-07-01

    Tussah silk fibroin fibres were modified by grafting with methacrylamide (MAA), with weight gains ranging between 2.6% and 71.4%. Raman and IR spectroscopic analyses showed that upon grafting the fibres underwent slight conformational changes towards a more unordered state, due to the covalent and hydrogen bonds interactions occurring between the polymer (polyMAA) and the amorphous domains of silk fibres. To test the stability towards alkaline hydrolysis, the untreated and MAA-grafted silk fibres (weight gain of 71.4%) were immersed in NaOH 5% at 50°C for different times; the IR and Raman spectroscopic techniques were utilized to elucidate the degradation mechanism as well as the rearrangements of the fibres induced by the treatment. Upon hydrolysis, both the untreated and grafted fibres underwent an enrichment in β-sheet conformation, due to the preferential removal of the unordered domains. As a result of the covalent interactions with silk fibroin, the polymer increased its stability towards alkaline hydrolysis, since its complete solubilization was avoided and the transformation of its CONH2 groups into COO(-) and COOH was delayed. Vibrational spectroscopy proved to be a valid technique to investigate the mechanism and the effects of the hydrolytic attack, which are both fundamental to design new-generation silk-based materials. PMID:27032490

  15. Effects of denervation, immobilization and cachexia on fibre size in the anterior tibial muscle of the rat.

    PubMed

    Lindboe, C F; Presthus, J

    1985-01-01

    The effects of denervation, immobilization and cachexia on the size of the various histochemical fibre types were studied in the anterior tibial muscle of male Wistar rats aged 60-100 days. Denervation was induced by unilateral sectioning of the sciatic nerve, immobilization by a plaster cast on one hindlimb and cachexia by restriction of food intake. In the anterior tibial muscle of the normal rat, three fibre types can be identified by myofibrillar ATPase stain after alkaline preincubation. These fibres were called dark (D-fibres), intermediate (I-fibres) and light fibres (L-fibres), respectively. The I-fibres correspond to the fast-twitch type 2 fibres and the L-fibres to the slow-twitch type 1 fibres. The D-fibres have intermediate characteristics, but they probably belong to the type 2 group. The three fibre types reacted differently to denervation, immobilization and cachexia. Denervation caused progressive atrophy of the D- and I-fibres and almost no change of the L-fibres. Immobilization caused minor reduction in size of the D- and I-fibres during the first days and no change thereafter, whereas the L-fibres showed transitory hypertrophy. Cachexia, on the other hand, resulted in progressive atrophy of all three fibre types but a predominant affection of the D- and I-fibres. The different susceptibilities of the various fibre types suggest different mechanisms for atrophy of muscle in these three conditions. PMID:3158148

  16. Cellular membrane trafficking of mesoporous silica nanoparticles

    SciTech Connect

    Fang, I-Ju

    2012-01-01

    This dissertation mainly focuses on the investigation of the cellular membrane trafficking of mesoporous silica nanoparticles. We are interested in the study of endocytosis and exocytosis behaviors of mesoporous silica nanoparticles with desired surface functionality. The relationship between mesoporous silica nanoparticles and membrane trafficking of cells, either cancerous cells or normal cells was examined. Since mesoporous silica nanoparticles were applied in many drug delivery cases, the endocytotic efficiency of mesoporous silica nanoparticles needs to be investigated in more details in order to design the cellular drug delivery system in the controlled way. It is well known that cells can engulf some molecules outside of the cells through a receptor-ligand associated endocytosis. We are interested to determine if those biomolecules binding to cell surface receptors can be utilized on mesoporous silica nanoparticle materials to improve the uptake efficiency or govern the mechanism of endocytosis of mesoporous silica nanoparticles. Arginine-glycine-aspartate (RGD) is a small peptide recognized by cell integrin receptors and it was reported that avidin internalization was highly promoted by tumor lectin. Both RGD and avidin were linked to the surface of mesoporous silica nanoparticle materials to investigate the effect of receptor-associated biomolecule on cellular endocytosis efficiency. The effect of ligand types, ligand conformation and ligand density were discussed in Chapter 2 and 3. Furthermore, the exocytosis of mesoporous silica nanoparticles is very attractive for biological applications. The cellular protein sequestration study of mesoporous silica nanoparticles was examined for further information of the intracellular pathway of endocytosed mesoporous silica nanoparticle materials. The surface functionality of mesoporous silica nanoparticle materials demonstrated selectivity among the materials and cancer and normal cell lines. We aimed to determine

  17. Evaluating a novel application of optical fibre evanescent field absorbance: rapid measurement of red colour in winegrape homogenates

    NASA Astrophysics Data System (ADS)

    Lye, Peter G.; Bradbury, Ronald; Lamb, David W.

    Silica optical fibres were used to measure colour (mg anthocyanin/g fresh berry weight) in samples of red wine grape homogenates via optical Fibre Evanescent Field Absorbance (FEFA). Colour measurements from 126 samples of grape homogenate were compared against the standard industry spectrophotometric reference method that involves chemical extraction and subsequent optical absorption measurements of clarified samples at 520 nm. FEFA absorbance on homogenates at 520 nm (FEFA520h) was correlated with the industry reference method measurements of colour (R2 = 0.46, n = 126). Using a simple regression equation colour could be predicted with a standard error of cross-validation (SECV) of 0.21 mg/g, with a range of 0.6 to 2.2 mg anthocyanin/g and a standard deviation of 0.33 mg/g. With a Ratio of Performance Deviation (RPD) of 1.6, the technique when utilizing only a single detection wavelength, is not robust enough to apply in a diagnostic sense, however the results do demonstrate the potential of the FEFA method as a fast and low-cost assay of colour in homogenized samples.

  18. 29Si NMR investigation of ORMOSIL layers used as luminophores' sol-gel matrices in a UV optical fibre sensor

    NASA Astrophysics Data System (ADS)

    Chodkowska, Eliza M.; Rayss, Jan

    2007-07-01

    The paper concerns the results of ORMOSIL layer's applied in an optical fibre ultraviolet sensor Nuclear Magnetic Resonance investigation. The layer which substituted for optical fibre's cladding in device's sensing part acted as a matrix for a coumarin's derivative. The dye is able to convert ultraviolet into visible radiation which could be easily detected. Thanks to the fact that the refractive indices of ORMOSIL layers may be controlled and reach a value characteristic for the fused silica glass a satisfying sensitivity of the device can be achieved. However it may be expected that both the structure and the composition of ORMOSIL matrices could influence the organic dye's behaviour. The aim of the experiment presented in the paper was to prove a relation between the sol's condensation time and a composition of the obtained gel's structure. The obtained NMR spectra gave the evidence of non-condensed -Si-O-C IIH 5(H) moieties existence in the solid gels. Moreover, even a 42-days-long process does not lead to the total condensation of ethoxysilanes' molecules. It is probable that the remaining ethoxy or silanol groups interact with transducer's molecules as well as influence the refractive index of the gel layer.

  19. Thermoforming of Continuous Fibre Reinforced Thermoplastic Composites

    SciTech Connect

    McCool, Rauri; Murphy, Adrian; Wilson, Ryan; Jiang Zhenyu; Price, Mark

    2011-05-04

    The introduction of new materials, particularly for aerospace products, is not a simple, quick or cheap task. New materials require extensive and expensive qualification and must meet challenging strength, stiffness, durability, manufacturing, inspection and maintenance requirements. Growth in industry acceptance for fibre reinforced thermoplastic composite systems requires the determination of whole life attributes including both part processing and processed part performance data. For thermoplastic composite materials the interactions between the processing parameters, in-service structural performance and end of life recyclability are potentially interrelated. Given the large number and range of parameters and the complexity of the potential relationships, understanding for whole life design must be developed in a systematic building block approach. To assess and demonstrate such an approach this article documents initial coupon level thermoforming trials for a commercially available fibre reinforced thermoplastic laminate, identifying the key interactions between processing and whole life performance characteristics. To examine the role of the thermoforming process parameters on the whole life performance characteristics of the formed part requires a series of manufacturing trials combined with a series of characterisation tests on the manufacturing trial output. Using a full factorial test programme and considering all possible process parameters over a range of potential magnitudes would result in a very large number of manufacturing trials and accompanying characterisation tests. Such an approach would clearly be expensive and require significant time to complete, therefore failing to address the key requirement for a future design methodology capable of rapidly generating design knowledge for new materials and processes. In this work the role of mould tool temperature and blank forming temperature on the thermoforming of a commercially available

  20. Q-switching of a thulium-doped fibre laser using a holmium-doped fibre saturable absorber

    SciTech Connect

    Sadovnikova, Ya E; Kamynin, V A; Kurkov, A S; Medvedkov, O I; Marakulin, A V; Minashina, L A

    2014-01-31

    We have proposed and demonstrated a new passively Q-switched thulium-doped fibre laser configuration. A distinctive feature of this configuration is the use of a heavily holmium-doped fibre for Q-switching. Lasing was obtained at 1.96 μm, with a pulse energy of 3 μJ and pulse duration of 600 ns. The highest pulse repetition rate was 80 kHz. (control of laser radiation parameters)

  1. Ultralow thermal sensitivity of phase and propagation delay in hollow core optical fibres

    NASA Astrophysics Data System (ADS)

    Slavík, Radan; Marra, Giuseppe; Fokoua, Eric Numkam; Baddela, Naveen; Wheeler, Natalie V.; Petrovich, Marco; Poletti, Francesco; Richardson, David J.

    2015-10-01

    Propagation time through an optical fibre changes with the environment, e.g., a change in temperature alters the fibre length and its refractive index. These changes have negligible impact in many key fibre applications, e.g., telecommunications, however, they can be detrimental in many others. Examples are fibre-based interferometry (e.g., for precise measurement and sensing) and fibre-based transfer and distribution of accurate time and frequency. Here we show through two independent experiments that hollow-core photonic bandgap fibres have a significantly smaller sensitivity to temperature variations than traditional solid-core fibres. The 18 times improvement observed, over 3 times larger than previously reported, makes them the most environmentally insensitive fibre technology available and a promising candidate for many next-generation fibre systems applications that are sensitive to drifts in optical phase or absolute propagation delay.

  2. Ultralow thermal sensitivity of phase and propagation delay in hollow core optical fibres

    PubMed Central

    Slavík, Radan; Marra, Giuseppe; Fokoua, Eric Numkam; Baddela, Naveen; Wheeler, Natalie V.; Petrovich, Marco; Poletti, Francesco; Richardson, David J.

    2015-01-01

    Propagation time through an optical fibre changes with the environment, e.g., a change in temperature alters the fibre length and its refractive index. These changes have negligible impact in many key fibre applications, e.g., telecommunications, however, they can be detrimental in many others. Examples are fibre-based interferometry (e.g., for precise measurement and sensing) and fibre-based transfer and distribution of accurate time and frequency. Here we show through two independent experiments that hollow-core photonic bandgap fibres have a significantly smaller sensitivity to temperature variations than traditional solid-core fibres. The 18 times improvement observed, over 3 times larger than previously reported, makes them the most environmentally insensitive fibre technology available and a promising candidate for many next-generation fibre systems applications that are sensitive to drifts in optical phase or absolute propagation delay. PMID:26490424

  3. Moisture Transport in Silica Gel Particle Beds: I. Theoretical Study

    SciTech Connect

    Pesaran, A. A.; Mills, A. F.

    1986-08-01

    Diffusion mechanisms of moisture within silica gel particles are investigated. It is found that for microporous silica gel surface diffusion is the dominant mechanism of moisture transport, while for macroporous silica gel both Knudsen and surface diffusion are important.

  4. HEALTH EFFECTS OF INHALED CRYSTALLINE AND AMORPHOUS SILICA

    EPA Science Inventory

    Recently, public concern regarding nonoccupational or ambient silica exposure, mainly to crystalline silica, has emerged making it important to evaluate background and ambient concentrations. Ambient emissions of silica rarely are estimated or measured in air pollution studies of...

  5. Tensile properties of glass/natural jute fibre-reinforced polymer bars for concrete reinforcement

    NASA Astrophysics Data System (ADS)

    Han, J. W.; Lee, S. K.; Kim, K. W.; Park, C. G.

    2015-12-01

    The tensile performance of glass/natural jute fibre-reinforced polymer (FRP) bar, intended for concrete reinforcement was evaluated as a function of volume fraction of natural jute fibre. Natural jute fibre, mixed at a ratio of 7:3 with vinyl ester, was surface-treated with a silane coupling agent and used to replaced glass fibre in the composite in volume fractions of 0%, 30%, 50%, 70%, and 100%. The tensile load-displacement curve showed nearly linear elastic behaviour up to 50% natural jute fibre, but was partially nonlinear at a proportion of 70%. However, the glass/natural jute FRP bars prepared using 100% natural jute fibre showed linear elastic behaviour. Tensile strength decreased as the natural jute fibre volume fraction increased because the tensile strength of natural jute fibre is much lower than that of glass fibre (about 1:8.65). The degree of reduction was not proportional to the natural jute fibre volume fraction due to the low density of natural jute fibre (1/2 that of glass fibre). Thus, as the mix proportion of natural jute fibre increased, the amount (wt%) and number of fibres used also increased.

  6. Chirality measurements using optical fibre long period gratings fabricated in high birefringent fibre

    NASA Astrophysics Data System (ADS)

    Korposh, S.; Tatam, R. P.; James, S. W.; Lee, S.-W.

    2015-07-01

    A Long period grating (LPG) with a period of 111 μm was fabricated in the highly birefringent (Hi-Bi) optical fibre with the aim of developing a sensor for chirality measurements. The LPG sensor was exposed to different concentrations of glucose D(+) and fructose D(-) in water, which have similar structures but exhibit opposite optical rotations, i.e. chirality. The behaviour of the resonance bands of the submodes corresponding to the two orthogonal polarization states was different depending on the chirality of the compound, thus allowing discrimination between two compounds.

  7. High-energy pulsed fibre laser based on a two-fibre assembly

    SciTech Connect

    Kobtsev, Sergey M; Kukarin, S V; Fedotov, Yu S

    2009-05-31

    We demonstrate for the first time a relatively simple fibre laser system with a passively Q-switched master oscillator and a polarised output pulse energy of up to 110 {mu}J at 1080 nm. The system is pumped by a single 12-W multimode cw source at 980 nm. Depending on the pump power, the pulse duration varies from 280 ns to 1.8 {mu}s and the pulse repetition rate, from 45 to 140 kHz. The maximum average output power is 5 W. The system has been tested for its performance in metal and glass processing. (lasers and amplifiers)

  8. Wave kinetics of random fibre lasers

    PubMed Central

    Churkin, D V.; Kolokolov, I V.; Podivilov, E V.; Vatnik, I D.; Nikulin, M A.; Vergeles, S S.; Terekhov, I S.; Lebedev, V V.; Falkovich, G.; Babin, S A.; Turitsyn, S K.

    2015-01-01

    Traditional wave kinetics describes the slow evolution of systems with many degrees of freedom to equilibrium via numerous weak non-linear interactions and fails for very important class of dissipative (active) optical systems with cyclic gain and losses, such as lasers with non-linear intracavity dynamics. Here we introduce a conceptually new class of cyclic wave systems, characterized by non-uniform double-scale dynamics with strong periodic changes of the energy spectrum and slow evolution from cycle to cycle to a statistically steady state. Taking a practically important example—random fibre laser—we show that a model describing such a system is close to integrable non-linear Schrödinger equation and needs a new formalism of wave kinetics, developed here. We derive a non-linear kinetic theory of the laser spectrum, generalizing the seminal linear model of Schawlow and Townes. Experimental results agree with our theory. The work has implications for describing kinetics of cyclical systems beyond photonics. PMID:25645177

  9. Smart Structures with Fibre-Optic Technologies

    SciTech Connect

    Del Grosso, Andrea; Zangani, Donato; Messervey, Thomas

    2008-07-08

    A number of smart structures have been proposed, and some of them realized, to reduce the effect that seismic motions induce on the structure themselves. In particular, active and semi-active control devices have been studied for being applied to buildings and bridges in seismic prone regions. The heart of the application for these devices consists of a network of sensors and computational nodes that produces the input to the actuating mechanisms. Despite the initial enthusiasm for these developments, only a few practical applications involving active devices have been implemented to-date, the main reason residing in questions concerning the reliability of active systems over time. Nevertheless, the allocation of sensory systems and computational intelligence in structures subjected to earthquakes can provide very important information on the real structural behavior, provide self-diagnosis functions after events, and allow for reliability estimates of critical components. The paper reviews several recently developed sensory devices and diagnostic algorithms that may be applied to existing structures or embedded in new ones for the above purpose. Special emphasis will be given to fibre optic technology and its applications.

  10. Smart Structures with Fibre-Optic Technologies

    NASA Astrophysics Data System (ADS)

    Del Grosso, Andrea; Zangani, Donato; Messervey, Thomas

    2008-07-01

    A number of smart structures have been proposed, and some of them realized, to reduce the effect that seismic motions induce on the structure themselves. In particular, active and semi-active control devices have been studied for being applied to buildings and bridges in seismic prone regions. The heart of the application for these devices consists of a network of sensors and computational nodes that produces the input to the actuating mechanisms. Despite the initial enthusiasm for these developments, only a few practical applications involving active devices have been implemented to-date, the main reason residing in questions concerning the reliability of active systems over time. Nevertheless, the allocation of sensory systems and computational intelligence in structures subjected to earthquakes can provide very important information on the real structural behavior, provide self-diagnosis functions after events, and allow for reliability estimates of critical components. The paper reviews several recently developed sensory devices and diagnostic algorithms that may be applied to existing structures or embedded in new ones for the above purpose. Special emphasis will be given to fibre optic technology and its applications.

  11. High gain holmium-doped fibre amplifiers.

    PubMed

    Simakov, Nikita; Li, Zhihong; Jung, Yongmin; Daniel, Jae M O; Barua, Pranabesh; Shardlow, Peter C; Liang, Sijing; Sahu, Jayanta K; Hemming, Alexander; Clarkson, W Andrew; Alam, Shaif-Ul; Richardson, David J

    2016-06-27

    We investigate the operation of holmium-doped fibre amplifiers (HDFAs) in the 2.1 µm spectral region. For the first time we demonstrate a diode-pumped HDFA. This amplifier provides a peak gain of 25 dB at 2040 nm with a 15 dB gain window spanning the wavelength range 2030 - 2100 nm with an external noise figure (NF) of 4-6 dB. We also compare the operation of HDFAs when pumped at 1950 nm and 2008 nm. The 1950 nm pumped HDFA provides 41 dB peak gain at 2060 nm with 15 dB of gain spanning the wavelength range 2050 - 2120 nm and an external NF of 7-10 dB. By pumping at the longer wavelength of 2008 nm the gain bandwidth of the amplifier is shifted to longer wavelengths and using this architecture a HDFA was demonstrated with a peak gain of 39 dB at 2090 nm and 15 dB of gain spanning the wavelength range 2050 - 2150 nm. The external NF over this wavelength range was 8-14 dB. PMID:27410557

  12. Dynamic damage in carbon-fibre composites.

    PubMed

    Bourne, N K; Parry, S; Townsend, D; Withers, P J; Soutis, C; Frias, C

    2016-07-13

    The Taylor test is used to determine damage evolution in carbon-fibre composites across a range of strain rates. The hierarchy of damage across the scales is key in determining the suite of operating mechanisms and high-speed diagnostics are used to determine states during dynamic loading. Experiments record the test response as a function of the orientation of the cylinder cut from the engineered multi-ply composite with high-speed photography and post-mortem target examination. The ensuing damage occurs during the shock compression phase but three other tensile loading modes operate during the test and these are explored. Experiment has shown that ply orientations respond to two components of release; longitudinal and radial as well as the hoop stresses generated in inelastic flow at the impact surface. The test is a discriminant not only of damage thresholds but of local failure modes and their kinetics. This article is part of the themed issue 'Multiscale modelling of the structural integrity of composite materials'. PMID:27242311

  13. Fibre optics improving deepwater rov pipeline inspection

    SciTech Connect

    McGregor, D.

    1983-09-01

    Pipeline inspection is a complex test requiring a variety of sensors. The trend in recent times has been to fit, simultaneously, all of the above sensors to a vehicle in order to maximise data collection from the pipeline in a single pass. This data is then processed in real time as the ROV travels the pipeline. Thus, a chart representing all the available data can be made available shortly after completion of a dive. The current generation of ROVs uses umbilicals containing various combinations of power conductors, co-axia and twisted pairs to carry the sensor data. These umbilicals, however, have inherent disadvantages which become apparent as sensor data increase in quantity and complexity. This disadvantage is the incompatibility of required high quality-data being transmitted to the surface and the large amounts of electrical energy demanded by the vehicle. Another disadvantage is the incompatibility between sensor signals in terms of frequency and power. However, to eliminate these problems, and to provide for future developments in ROV technology, the new generation of ROVs utilise fibre-optic conductors, the advantages being that they are immune from electro-magnetic interference, they offer wider band-widths with lower power losses (typically 5 dB or less per km) than conventional copper conductors, and are easier to handle as umbilicals lengthen due to demand for vehicles to reach greater depths. Typically, these new umbilicals will be 1.5 km in length.

  14. PRAXIS: low thermal emission high efficiency OH suppressed fibre spectrograph

    NASA Astrophysics Data System (ADS)

    Content, Robert; Bland-Hawthorn, Joss; Ellis, Simon; Gers, Luke; Haynes, Roger; Horton, Anthony; Lawrence, Jon; Leon-Saval, Sergio; Lindley, Emma; Min, Seong-Sik; Shortridge, Keith; Staszak, Nick; Trinh, Christopher; Xavier, Pascal; Zhelem, Ross

    2014-07-01

    PRAXIS is a second generation instrument that follows on from GNOSIS, which was the first instrument using fibre Bragg gratings for OH suppression to be deployed on a telescope. The Bragg gratings reflect the NIR OH lines while being transparent to the light between the lines. This gives in principle a much higher signal-noise ratio at low resolution spectroscopy but also at higher resolutions by removing the scattered wings of the OH lines. The specifications call for high throughput and very low thermal and detector noise so that PRAXIS will remain sky noise limited even with the low sky background levels remaining after OH suppression. The optical and mechanical designs are presented. The optical train starts with fore-optics that image the telescope focal plane on an IFU which has 19 hexagonal microlenses each feeding a multi-mode fibre. Seven of these fibres are attached to a fibre Bragg grating OH suppression system while the others are reference/acquisition fibres. The light from each of the seven OH suppression fibres is then split by a photonic lantern into many single mode fibres where the Bragg gratings are imprinted. Another lantern recombines the light from the single mode fibres into a multi-mode fibre. A trade-off was made in the design of the IFU between field of view and transmission to maximize the signal-noise ratio for observations of faint, compact objects under typical seeing. GNOSIS used the pre-existing IRIS2 spectrograph while PRAXIS will use a new spectrograph specifically designed for the fibre Bragg grating OH suppression and optimised for 1.47 μm to 1.7 μm (it can also be used in the 1.09 μm to 1.26 μm band by changing the grating and refocussing). This results in a significantly higher transmission due to high efficiency coatings, a VPH grating at low incident angle and optimized for our small bandwidth, and low absorption glasses. The detector noise will also be lower thanks to the use of a current generation HAWAII-2RG detector

  15. Bismuth-doped optical fibres: A new breakthrough in near-IR lasing media

    SciTech Connect

    Dianov, Evgenii M

    2012-09-30

    Recent results demonstrate that bismuth-doped optical fibres have considerable potential as near-IR active lasing media. This paper examines bismuth-doped fibres intended for the fabrication of fibre lasers and optical amplifiers and reviews recent results on the luminescence properties of various types of bismuth-doped fibres and the performance of bismuth-doped fibre lasers and optical amplifiers for the spectral range 1150 - 1550 nm. Problems are discussed that have yet to be solved in order to improve the efficiency of the bismuth lasers and optical amplifiers. (optical fibres, lasers and amplifiers. properties and applications)

  16. The effect of aluminium on the post-anneal concentration of ion implanted bismuth in silica thin films

    NASA Astrophysics Data System (ADS)

    Southern-Holland, R.; Halsall, M. P.; Crowe, I. F.; Yang, P.; Gwilliam, R. M.

    2015-12-01

    We present a study of bismuth and aluminium co-implanted silica thin films and the effectiveness of post implantation annealing at activating Bismuth related photoluminescence. The only emission seen in photoluminescence from any of the samples was centred at 1160 nm and is of the kind generally reported as due to silicon dislocation loops. In particular, the layers did not exhibit the broad NIR emission in photoluminescence as reported by other authors in Bismuth doped silica fibres. In order to study the retention of the Bismuth in the layers after annealing Rutherford Backscattering measurements were conducted on the samples, these found that the concentration of bismuth in the samples was greatly reduced following the annealing process when compared to the concentration implanted and explains why we measured no emission from bismuth. The concentration of bismuth remaining in the sample post anneal depended on the initial implant doses of bismuth and aluminium. We propose that aluminium plays the role of increasing the solubility of bismuth in oxide but that this was not sufficient in our samples to observe the photoemission reported for fibre materials.

  17. Nanoscale control of silica particle formation via silk-silica fusion proteins for bone regeneration.

    PubMed

    Mieszawska, Aneta J; Nadkarni, Lauren D; Perry, Carole C; Kaplan, David L

    2010-10-26

    The biomimetic design of silk/silica fusion proteins was carried out, combining the self assembling domains of spider dragline silk (Nephila clavipes) and silaffin derived R5 peptide of Cylindrotheca fusiformis that is responsible for silica mineralization. Genetic engineering was used to generate the protein-based biomaterials incorporating the physical properties of both components. With genetic control over the nanodomain sizes and chemistry, as well as modification of synthetic conditions for silica formation, controlled mineralized silk films with different silica morphologies and distributions were successfully generated; generating 3D porous networks, clustered silica nanoparticles (SNPs), or single SNPs. Silk serves as the organic scaffolding to control the material stability and multiprocessing makes silk/silica biomaterials suitable for different tissue regenerative applications. The influence of these new silk-silica composite systems on osteogenesis was evaluated with human mesenchymal stem cells (hMSCs) subjected to osteogenic differentiation. hMSCs adhered, proliferated, and differentiated towards osteogenic lineages on the silk/silica films. The presence of the silica in the silk films influenced osteogenic gene expression, with the upregulation of alkaline phosphatase (ALP), bone sialoprotein (BSP), and collagen type 1 (Col 1) markers. Evidence for early bone formation as calcium deposits was observed on silk films with silica. These results indicate the potential utility of these new silk/silica systems towards bone regeneration. PMID:20976116

  18. DNA Binding to the Silica Surface.

    PubMed

    Shi, Bobo; Shin, Yun Kyung; Hassanali, Ali A; Singer, Sherwin J

    2015-08-27

    We investigate the DNA-silica binding mechanism using molecular dynamics simulations. This system is of technological importance, and also of interest to explore how negatively charged DNA can bind to a silica surface, which is also negatively charged at pH values above its isoelectric point near pH 3. We find that the two major binding mechanisms are attractive interactions between DNA phosphate and surface silanol groups and hydrophobic bonding between DNA base and silica hydrophobic region. Umbrella sampling and the weighted histogram analysis method (WHAM) are used to calculate the free energy surface for detachment of DNA from a binding configuration to a location far from the silica surface. Several factors explain why single-stranded DNA (ssDNA) has been observed to be more strongly attracted to silica than double-stranded (dsDNA): (1) ssDNA is more flexible and therefore able to maximize the number of binding interactions. (2) ssDNA has free unpaired bases to form hydrophobic attachment to silica while dsDNA has to break hydrogen bonds with base partners to get free bases. (3) The linear charge density of dsDNA is twice that of ssDNA. We devise a procedure to approximate the atomic forces between biomolecules and amorphous silica to enable large-scale biomolecule-silica simulations as reported here. PMID:25966319

  19. Biomimetic silica encapsultation of living cells

    NASA Astrophysics Data System (ADS)

    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.

  20. Reusable silica surface-insulation material

    NASA Technical Reports Server (NTRS)

    Goldstein, H. E.; Smith, M.; Leiser, D.

    1973-01-01

    Material was specifically developed for manufacture of insulating tiles, but it can be molded into other shapes as required. Basic raw materials are high-purity silica fiber, fumed-silica powder, and reagent-grade starch. Only purest materials are used, and care must be taken to avoid contamination during processing.