WorldWideScience

Sample records for hollow fibre module

  1. Air gap membrane distillation. 2. Model validation and hollow fibre module performance analysis

    NARCIS (Netherlands)

    Guijt, C.M.; Meindersma, G.W.; Reith, T.; de Haan, A.B.

    2005-01-01

    In this paper the experimental results of counter current flow air gap membrane distillation experiments are presented and compared with predictive model calculations. Measurements were carried out with a cylindrical test module containing a single hollow fibre membrane in the centre and a

  2. Spectral broadening of 25 fs laser pulses via self-phase modulation in a neon filled hollow core fibre

    Energy Technology Data Exchange (ETDEWEB)

    Weichert, Stefan

    2017-05-15

    The goal of this work was the realisation of a setup for spectral broadening and subsequent compression of 25 fs laser pulses provided by a commercial Ti:Sapphire based CPA laser system by means of the hollow core fibre chirped mirror compressor technique. For the spectral broadening a vessel containing the hollow waveguide filled with a noble gas serving as the nonlinear medium was set up and an alignment procedure was developed. Neon was chosen as the nonlinear medium for the self-phase modulation of the pulses. With this setup spectral broadening, sufficient for supporting sub 5 fs pulses, was observed. The spectra at different input energies and neon gas pressures were measured and the stability of these and their respective Fourier transform-limited pulses determined in order to find an operating point. For the compression of the self-phase modulated pulses a chirped mirror compressor was designed and set up, but not tested yet. The layout of a single-shot intensity autocorrelator capable of estimating the pulse duration of sub 10 fs pulses was given.

  3. Non-resonant wavelength modulation saturation spectroscopy in acetylene-filled hollow-core photonic bandgap fibres applied to modulation-free laser diode stabilisation.

    Science.gov (United States)

    Pineda-Vadillo, Pablo; Lynch, Michael; Charlton, Christy; Donegan, John F; Weldon, Vincent

    2009-12-07

    In this paper the application of Wavelength Modulation (WM) techniques to non-resonant saturation spectroscopy in acetylene-filled Hollow-Core Photonic Bandgap Fibres (HC-PBFs) and modulation-free Laser Diode (LD) frequency stabilisation is investigated. In the first part WM techniques are applied to non-resonant pump-probe saturation of acetylene overtone rotational transitions in a HC-PBF. A high-power DFB chip-on-carrier mounted LD is used in conjunction with a tuneable External Cavity Laser (ECL) and the main saturation parameters are characterized. In the second part a novel feedback system to stabilize the DFB emission wavelength based on the WM saturation results is implemented. Modulation-free locking of the DFB laser frequency to the narrow linewidth saturation feature is achieved for both constant and variable LD temperatures.

  4. Microporous hollow fibre membrane modules as gas-liquid contactors. Part 1. Physical mass transfer processes : A specific application

    NARCIS (Netherlands)

    Kreulen, H.; Versteeg, G.F.; Swaaij, W.P.M. van

    1993-01-01

    Gas-liquid mass transfer has been studied in a membrane module with non-wetted microporous fibres in the laminar flow regime. This new type of gas/liquid contactor can be operated stabily over a large range of gas and liquid flows because gas and liquid phase do not influence each other directly.

  5. Hollow fibre supported liquid membrane extraction of ...

    African Journals Online (AJOL)

    A simple sample pre-treatment method utilizing hollow fibre supported liquid membrane (HFSLM) was carried out on pharmaceuticals samples comprising of cough syrups (CS1 and CS2) and an anti-inflammatory product (AI). The active ingredients targeted in the extraction process were diphenylhydramine (DPH), ...

  6. Wet spinning of asymmetric hollow fibre membranes for gas separation

    NARCIS (Netherlands)

    van 't Hof, Jacob Adriaan

    1988-01-01

    This thesis describes the spinning and characterizatin of hollow fibre membranes for gas separation. The type of fibres studied here are made by a wet spinning process. A homogeneous solution is prepared, consisting of a polymer in a suitable organic solvent, and extruded as a hollow fibre. Both the

  7. UV-enhanced sacrificial layer stabilised graphene oxide hollow fibre membranes for nanofiltration

    OpenAIRE

    J. Y. Chong; Aba, N. F. D.; Wang, B.; Mattevi, C.; K. Li

    2015-01-01

    Graphene oxide (GO) membranes have demonstrated great potential in gas separation and liquid filtration. For upscale applications, GO membranes in a hollow fibre geometry are of particular interest due to the high-efficiency and easy-assembly features at module level. However, GO membranes were found unstable in dry state on ceramic hollow fibre substrates, mainly due to the drying-related shrinkage, which has limited the applications and post-treatments of GO membranes. We demonstrate here t...

  8. High strength and low weight hollow carbon fibres

    Science.gov (United States)

    Köhler, T.; Brüll, R.; Pursche, F.; Langgartner, J.; Seide, G.; Gries, T.

    2017-10-01

    Carbon fibres have strengths of 2.5 to 5 GPa in the fibre direction and an elastic modulus of 200 to 500 GPa. Carbon fibres have equal mechanical properties as steel but 20% of the weight. But the material is more expensive than steel. Therefore, they are only used in industry sectors where the benefits legitimate the high costs. The use of hollow rather than solid fibres allows an even lower weight of the components. At the same time, similar mechanical properties are achieved by the circular cross section. Carbon fibres are obtained from polyacrylonitrile fibers (PAN). These can be produced as hollow fibres. As a first step stabilization and carbonization of hollow PAN precursors is investigated to produce hollow carbon fibres.

  9. A microring multimode laser using hollow polymer optical fibre

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 75; Issue 5. A microring ... Keywords. Dye-doped optical fibre; fibre laser; microcavity; whispering gallery mode. ... Cylindrical microcavities with diameters 155, 340 and 615 m were fabricated from a dye-doped hollow polymer optical fibre preform. An average mode ...

  10. Safety of carbon fibre reinforced plastic hollow sections in ...

    African Journals Online (AJOL)

    The use of steel hollow sections as compression members in structures has been a common practice. This study highlights the safety of using Carbon Fibre Reinforced Plastic (CFRP) hollow sections as compression structural members. The primary compression members in structures are columns and this study uses Finite ...

  11. Facile synthesis of ZnO hollow fibres

    Indian Academy of Sciences (India)

    WINTEC

    Abstract. In this paper, cotton fibres were used as bio-template to successfully synthesize new ceramic mate- rials, ZnO hollow fibres and in an effort to explore the synthesis condition, and simplify the synthesis procedure. In this synthesis, a direct thermal decomposition of zinc acetate dihydrate coated on the surface of ...

  12. UV-Enhanced Sacrificial Layer Stabilised Graphene Oxide Hollow Fibre Membranes for Nanofiltration

    Science.gov (United States)

    Chong, J. Y.; Aba, N. F. D.; Wang, B.; Mattevi, C.; Li, K.

    2015-11-01

    Graphene oxide (GO) membranes have demonstrated great potential in gas separation and liquid filtration. For upscale applications, GO membranes in a hollow fibre geometry are of particular interest due to the high-efficiency and easy-assembly features at module level. However, GO membranes were found unstable in dry state on ceramic hollow fibre substrates, mainly due to the drying-related shrinkage, which has limited the applications and post-treatments of GO membranes. We demonstrate here that GO hollow fibre membranes can be stabilised by using a porous poly(methyl methacrylate) (PMMA) sacrificial layer, which creates a space between the hollow fibre substrate and the GO membrane thus allowing stress-free shrinkage. Defect-free GO hollow fibre membrane was successfully determined and the membrane was stable in a long term (1200 hours) gas-tight stability test. Post-treatment of the GO membranes with UV light was also successfully accomplished in air, which induced the creation of controlled microstructural defects in the membrane and increased the roughness factor of the membrane surface. The permeability of the UV-treated GO membranes was greatly enhanced from 0.07 to 2.8 L m-2 h-1 bar-1 for water, and 0.14 to 7.5 L m-2 h-1 bar-1 for acetone, with an unchanged low molecular weight cut off (~250 Da).

  13. Dual hollow-core anti-resonant fibres

    Science.gov (United States)

    Wheeler, N. V.; Bradley, T. D.; Hayes, J. R.; Jasion, G. T.; Chen, Y.; Sandoghchi, S. R.; Horak, P.; Poletti, F.; Petrovich, M. N.; Richardson, D. J.

    2016-04-01

    While hollow core-photonic crystal fibres are now a well-established fibre technology, the majority of work on these speciality fibres has been on designs with a single core for optical guidance. In this paper we present the first dual hollow-core anti-resonant fibres (DHC-ARFs). The fibres have high structural uniformity and low loss (minimum loss of 0.5 dB/m in the low loss guidance window) and demonstrate regimes of both inter-core coupling and zero coupling, dependent on the wavelength of operation, input polarisation, core separation and bend radius. In a DHC-ARF with a core separation of 4.3 μm, we find that with an optimised input polarisation up to 65% of the light guided in the launch core can be coupled into the second core, opening up applications in power delivery, gas sensing and quantum optics.

  14. Towards implementation of hollow core fibres for surgical applications

    Science.gov (United States)

    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.

  15. Hollow-core photonic-crystal fibres for laser dentistry

    Energy Technology Data Exchange (ETDEWEB)

    Konorov, Stanislav O [Physics Department, International Laser Center, M V Lomonosov Moscow State University, Vorob' evy gory, 119899 Moscow (Russian Federation); Mitrokhin, Vladimir P [Physics Department, International Laser Center, M V Lomonosov Moscow State University, Vorob' evy gory, 119899 Moscow (Russian Federation); Fedotov, Andrei B [Physics Department, International Laser Center, M V Lomonosov Moscow State University, Vorob' evy gory, 119899 Moscow (Russian Federation); Sidorov-Biryukov, Dmitrii A [Physics Department, International Laser Center, M V Lomonosov Moscow State University, Vorob' evy gory, 119899 Moscow (Russian Federation); Beloglazov, Valentin I [Technology and Equipment for Glass Structures Institute, pr. Stroitelei 1, 410044 Saratov (Russian Federation); Skibina, Nina B [Technology and Equipment for Glass Structures Institute, pr. Stroitelei 1, 410044 Saratov (Russian Federation); Wintner, Ernst [Institut fuer Photonik, Technische Universitaet Wien, Gusshausstrasse 27/387, 1040 Wien (Austria); Scalora, Michael [Weapons Sciences Directorate, US Army Aviation and Missile Command Huntsville, AL 35898-5000 (United States); Zheltikov, Aleksei M [Physics Department, International Laser Center, M V Lomonosov Moscow State University, Vorob' evy gory, 119899 Moscow (Russian Federation)

    2004-04-07

    Hollow-core photonic-crystal fibres (PCFs) for the delivery of high-fluence laser radiation capable of ablating tooth enamel are developed. Sequences of picosecond pulses of 1.06 {mu}m Nd:YAG-laser radiation with a total energy of about 2 mJ are transmitted through a hollow-core photonic-crystal fibre with a core diameter of approximately 14 {mu}m and are focused on a tooth surface in vitro to ablate dental tissue. The hollow-core PCF is shown to support the single-fundamental-mode regime for 1.06 {mu}m laser radiation, serving as a spatial filter and allowing the laser beam quality to be substantially improved. The same fibre is used to transmit emission from plasmas produced by laser pulses on the tooth surface in the backward direction for detection and optical diagnostics.

  16. Low cost membrane contactors based on hollow fibres

    Science.gov (United States)

    Dohnal, Mirko; Vesely, Tomas; Raudensky, Miroslav

    2012-04-01

    Membrane contactors are used to solve different chemical engineering tasks (e.g. water saturation with gases). Such elements are traditionally used for bubble less oxidation of blood. However, their industrial applications are rather limited by their high investment costs. This is probably the main reason why membrane contactors are not used so widely, e.g. classical absorbers, etc. If potted bundles of hollow fibres are available, then it is a relatively simple task to design an ad hoc membrane contactor. However, it must be emphasised that to achieve the highest mass transfer efficiency requires a rather time-consuming tuning of each ad hoc designed contactor. To check the differences by water evaporation were aligned two modes, the water inside the hollow fibre membrane and fan air outside, next with the water outsides and flowing pressure air inside the membrane.

  17. Low cost membrane contactors based on hollow fibres

    Directory of Open Access Journals (Sweden)

    Raudensky Miroslav

    2012-04-01

    Full Text Available Membrane contactors are used to solve different chemical engineering tasks (e.g. water saturation with gases. Such elements are traditionally used for bubble less oxidation of blood. However, their industrial applications are rather limited by their high investment costs. This is probably the main reason why membrane contactors are not used so widely, e.g. classical absorbers, etc. If potted bundles of hollow fibres are available, then it is a relatively simple task to design an ad hoc membrane contactor. However, it must be emphasised that to achieve the highest mass transfer efficiency requires a rather time-consuming tuning of each ad hoc designed contactor. To check the differences by water evaporation were aligned two modes, the water inside the hollow fibre membrane and fan air outside, next with the water outsides and flowing pressure air inside the membrane.

  18. Mathematical modelling of dextran filtration through hollow fibre membranes

    DEFF Research Database (Denmark)

    Vinther, Frank; Pinelo, Manuel; Brøns, Morten

    2014-01-01

    In this paper we present a mathematical model of an ultrafiltration process. The results of the model are produced using standard numerical techniques with Comsol Multiphysics. The model describes the fluid flow and separation in hollow fibre membranes. The flow of solute and solvent within...... either increase or decrease as a function of pressure. The influence of a concentration dependent viscosity is to increase the concentration on the membrane surface. This leads to a decrease in both the observed and the intrinsic rejection, when compared to a constant viscosity. For small values...

  19. Metal-assisted coupling to hollow-core photonic crystal fibres

    DEFF Research Database (Denmark)

    Sørensen, Thorkild; Hansen, Theis Peter; Bjarklev, Anders Overgaard

    2005-01-01

    Selective coupling to the fundamental mode of short hollow-core photonic bandgap fibres without exciting cladding modes is improved by gold-coated fibre end facets. Cladding modes are suppressed by 20–30 dB for single-and multimode fibre launch, respectively, while in-band power loss is 3–8 dB....

  20. Supported graphene oxide hollow fibre membrane for oily wastewater treatment

    Science.gov (United States)

    Othman, Nur Hidayati; Alias, Nur Hashimah; Shahruddin, Munawar Zaman; Hussein, Siti Nurliyana Che Mohamed; Dollah, Aqilah

    2017-12-01

    Oil and gas industry deals with a large amount of undesirable discharges of liquid, solid, and gaseous wastes and the amounts can considerably change during the production phases. Oilfield wastewater or produced water is known to constitute various organic and inorganic components. Discharging the produced water can pollute surface and underground water and therefore the necessity to treat this oily wastewater is an inevitable challenge. The current technologies for the treatment of this metastable oil-in-water are not really effective and very pricey. As a result, there is a great interest from many parties around the world in finding cost-effective technologies. In recent years, membrane processes have been utilized for oily wastewater treatment. In these work, a graphene oxide membrane supported on a highly porous Al2O3 hollow fibre was prepared using vacuum assisted technique and its performance in treating oily wastewater was investigated. Graphene oxide (GO) was prepared using a modified Hummer's method and further characterized using XRD, FTIR, TGA and SEM. The results showed that the GO was successfully synthesized. The GO membrane was deposited on alumina hollow fibre substrates. The membrane performance was then investigated using dead-end filtration setup with synthetic oily wastewater as a feed. The effects of operating times on rejection rate and permeate flux were investigated. The experimental results showed that the oil rejections were over 90%. It was concluded that the supported GO membrane developed in this study may be considered feasible in treating oily wastewater. Detail study on the effects of transmembrane pressure, oil concentration, pH and fouling should be carried out in the future

  1. Multimode laser emission from dye-doped hollow polymer optical fibre

    Indian Academy of Sciences (India)

    2014-02-09

    Feb 9, 2014 ... Home; Journals; Pramana – Journal of Physics; Volume 82; Issue 2. Multimode laser emission from dye-doped hollow polymer optical fibre ... Well-resolved multimode laser emission was observed for the first time from a freestanding microring cavity based on Rhodamine B dye-doped hollow polymer ...

  2. Analysis of hollow fibre membrane systems for multicomponent gas separation

    KAUST Repository

    Khalilpour, Rajab

    2013-02-01

    This paper analysed the performance of a membrane system over key design/operation parameters. A computation methodology is developed to solve the model of hollow fibre membrane systems for multicomponent gas feeds. The model represented by a nonlinear differential algebraic equation system is solved via a combination of backward differentiation and Gauss-Seidel methods. Natural gas sweetening problem is investigated as a case study. Model parametric analyses of variables, namely feed gas quality, pressure, area, selectivity and permeance, resulted in better understanding of operating and design optima. Particularly, high selectivities and/or permeabilities are shown not to be necessary targets for optimal operation. Rather, a medium selectivity (<60 in the given example) combined with medium permeance (∼300-500×10-10mol/sm2Pa in the given case study) is more advantageous. This model-based membrane systems engineering approach is proposed for the synthesis of efficient and cost-effective multi-stage membrane networks. © 2012 The Institution of Chemical Engineers.

  3. Lamb-Dicke spectroscopy of atoms in a hollow-core photonic crystal fibre

    Science.gov (United States)

    Okaba, Shoichi; Takano, Tetsushi; Benabid, Fetah; Bradley, Tom; Vincetti, Luca; Maizelis, Zakhar; Yampol'skii, Valery; Nori, Franco; Katori, Hidetoshi

    2014-01-01

    Unlike photons, which are conveniently handled by mirrors and optical fibres without loss of coherence, atoms lose their coherence via atom–atom and atom–wall interactions. This decoherence of atoms deteriorates the performance of atomic clocks and magnetometers, and also hinders their miniaturization. Here we report a novel platform for precision spectroscopy. Ultracold strontium atoms inside a kagome-lattice hollow-core photonic crystal fibre are transversely confined by an optical lattice to prevent atoms from interacting with the fibre wall. By confining at most one atom in each lattice site, to avoid atom–atom interactions and Doppler effect, a 7.8-kHz-wide spectrum is observed for the 1S0−3P1(m=0) transition. Atoms singly trapped in a magic lattice in hollow-core photonic crystal fibres improve the optical depth while preserving atomic coherence time. PMID:24934478

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

    Science.gov (United States)

    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.

  5. Potential glucose monitoring of blood plasma using hollow core photonic crystal fibre

    Science.gov (United States)

    Horan, L. E.; Khara, G.; Rutowska, M.; Ellis, A. D.; Garcia Gunning, F. C.

    2011-05-01

    The ratio (ζ) of surface tension to viscosity of liquids can be determined using hollow core photonic crystal fibres (HCPCF), and we show here techniques to determine ζ of glucose levels within fluids, of nano-litre quantities. We demonstrate an optically integrated micro-capillary viscometer, to determine the concentrations of nano-litre solutions based on properties of their flow within HC-PCF. The filling of the fibres with liquids within a given range of refractive index will induce a shift in the photonic band gap of the fibre, allowing guidance of light at wavelengths that were originally outside the bandgap of the HC-PCF.

  6. Sub-critical long-term operation of industrial scale hollow-fibre membranes in a submerged anaerobic MBR (HF-SAnMBR) system

    OpenAIRE

    Robles Martínez, Ángel; Ruano García, María Victoria; Ribes Bertomeu, José; Ferrer, J.

    2012-01-01

    The aim of this study was to evaluate the long-term performance of hollow-fibre (HF) membranes used to treat urban wastewater in a submerged anaerobic MBR when operating sub-critically. To this end, a demonstration plant with two industrial scale HF ultrafiltration membrane modules was operated under different conditions. The main factor affecting membrane performance was the concentration of mixed liquor total solids (MLTS). The reversible fouling rate remained low even when MLTS levels (abo...

  7. Mode multiplexing at 2×20Gbps over 19-cell hollow-core photonic band gap fibre

    DEFF Research Database (Denmark)

    Carpenter, Joel; Xu, Jing; Peucheret, Christophe

    2012-01-01

    This paper demonstrates the first mode-multiplexed system over 19-cell hollow-core photonic band gap fibre, at 2×20Gbps using the LP0,1 and LP2,1-like modes.......This paper demonstrates the first mode-multiplexed system over 19-cell hollow-core photonic band gap fibre, at 2×20Gbps using the LP0,1 and LP2,1-like modes....

  8. 4.4-μm Raman laser based on hollow-core silica fibre

    Science.gov (United States)

    Gladyshev, A. V.; Kosolapov, A. F.; Khudyakov, M. M.; Yatsenko, Yu. P.; Kolyadin, A. N.; Krylov, A. A.; Pryamikov, A. D.; Biriukov, A. S.; Likhachev, M. E.; Bufetov, I. A.; Dianov, E. M.

    2017-06-01

    A Raman laser with a wavelength exceeding 4 μm is designed for the first time. Using a revolver silica fibre with a hollow core filled with molecular hydrogen (1H2) as an active medium, we have obtained SRS lasing at a wavelength of 4.4 μm under pumping by a pulsed erbium fibre laser (λ = 1.56 μm, τ = 2 ns). The SRS conversion quantum efficiency reaches 15 %, and the maximum output peak power at a wavelength of 4.4 μm is 0.6 kW.

  9. Mathematical modelling of cell layer growth in a hollow fibre bioreactor.

    Science.gov (United States)

    Chapman, Lloyd A C; Whiteley, Jonathan P; Byrne, Helen M; Waters, Sarah L; Shipley, Rebecca J

    2017-04-07

    Generating autologous tissue grafts of a clinically useful volume requires efficient and controlled expansion of cell populations harvested from patients. Hollow fibre bioreactors show promise as cell expansion devices, owing to their potential for scale-up. However, further research is required to establish how to specify appropriate hollow fibre bioreactor operating conditions for expanding different cell types. In this study we develop a simple model for the growth of a cell layer seeded on the outer surface of a single fibre in a perfused hollow fibre bioreactor. Nutrient-rich culture medium is pumped through the fibre lumen and leaves the bioreactor via the lumen outlet or passes through the porous fibre walls and cell layer, and out via ports on the outer wall of the extra-capillary space. Stokes and Darcy equations for fluid flow in the fibre lumen, fibre wall, cell layer and extra-capillary space are coupled to reaction-advection-diffusion equations for oxygen and lactate transport through the bioreactor, and to a simple growth law for the evolution of the free boundary of the cell layer. Cells at the free boundary are assumed to proliferate at a rate that increases with the local oxygen concentration, and to die and detach from the layer if the local fluid shear stress or lactate concentration exceed critical thresholds. We use the model to predict operating conditions that maximise the cell layer growth for different cell types. In particular, we predict the optimal flow rate of culture medium into the fibre lumen and fluid pressure imposed at the lumen outlet for cell types with different oxygen demands and fluid shear stress tolerances, and compare the growth of the cell layer when the exit ports on the outside of the bioreactor are open with that when they are closed. Model simulations reveal that increasing the inlet flow rate and outlet fluid pressure increases oxygen delivery to the cell layer and, therefore, the growth rate of cells that are

  10. Gamma irradiation of minimal latency Hollow-Core Photonic Bandgap Fibres

    CERN Document Server

    Olanterae, L; Richardson, D J; Vasey, F; Wooler, J P; Petrovich, M N; Wheeler, N V; Poletti, F; Troska, J

    2013-01-01

    Hollow-Core Photonic-Bandgap Fibres (HC-PBGFs) offer several distinct advantages over conventional fibres, such as low latency and radiation hardness; properties that make HC-PBGFs interesting for the high energy physics community. This contribution presents the results from a gamma irradiation test carried out using a new type of HC-PBGF that combines sufficiently low attenuation over distances that are compatible with high energy physics applications together with a transmission bandwidth that covers the 1550 nm region. The radiation induced attenuation of the HC-PBGF was two orders of magnitude lower than that of a conventional fibre during a 67.5 h exposure to gamma-rays, resulting in a radiation-induced attenuation of only 2.1 dB/km at an accumulated dose of 940 kGy.

  11. Tube-side mass transfer for hollow fibre membrane contactors operated in the low Graetz range.

    Science.gov (United States)

    Wang, C Y; Mercer, E; Kamranvand, F; Williams, L; Kolios, A; Parker, A; Tyrrel, S; Cartmell, E; McAdam, E J

    2017-02-01

    Transformation of the tube-side mass transfer coefficient derived in hollow fibre membrane contactors (HFMC) of different characteristic length scales (equivalent diameter and fibre length) has been studied when operated in the low Graetz range (Gzmass transfer is generally described by the Graetz problem (Sh=3.67) which assumes that the concentration profile comprises a constant shape over the fibre radius. In this study, it is experimentally evidenced that this assumption over predicts mass transfer within the low Graetz range. Furthermore, within the low Gz range (below 2), a proportional relationship between the experimentally determined mass transfer coefficient (Kov ) and the Graetz number has been identified. For Gz numbers below 2, the experimental Sh number approached unity, which suggests that mass transfer is strongly dependent upon diffusion. However, within this diffusion controlled region of mass transfer, tube-side fluid velocity remained important. For Gz numbers above 2, Sh could be satisfactorily described by extension to the Lévêque solution, which can be ascribed to the constrained growth of the concentration boundary layer adjacent to the fibre wall. Importantly this study demonstrates that whilst mass transfer in the low Graetz range does not explicitly conform to either the Graetz problem or classical Lévêque solution, it is possible to transform the experimentally derived overall mass transfer coefficient (Kov ) between characteristic length scales (dh and L). T h is was corroborated by comparison of the empirical relationship determined in this study (Sh=0.36Gz) with previously published studies operated in the low Gz range. This analysis provides important insight for process design when slow tube-side flows, or low Schmidt numbers (coincident with gases) constrain operation of hollow fibre membrane contactors to the low Gz range.

  12. Pulsed photothermal interferometry for high sensitivity gas detection with hollow-core photonic bandgap fibre

    Science.gov (United States)

    Lin, Yuechuan; Jin, Wei; Yang, Fan; Ho, Hoi Lut

    2017-04-01

    Pulsed photothermal interferometry (PTI) gas sensor with hollow-core photonic bandgap fibre (HC-PBF) is demonstrated with a Sagnac interferometer-based phase detection system. Under the condition of constant peak pump power, the optimal pulse duration is found to be > 1:2 μs for detecting low-concentration of trace gases in nitrogen, limited by thermal conduction of gases within the hollow-core. Preliminary experiments with a 0.62-mlong HC-PBF gas cell, low peak power ( 20:2mW) and a boxcar averager with 10k average times demonstrated a detection limit of 3:3 p:p:m acetylene. Detection limit down to ppb or lower is expected with high peak power pump pulses.

  13. Reclamation of the wastewater from an industrial park using hollow-fibre and spiral-wound membranes: 50 m3 d(-1) pilot testing and cost evaluation.

    Science.gov (United States)

    Chu, C P; Jiaoa, S R; Hung, J M; Lu, C J; Chung, Y J

    2009-08-01

    The feasibility of reclaiming effluent from industrial park wastewater treatment plants through a membrane process was evaluated in three phases. In phase 1 we selected nine wastewater treatment plants (WWTPs), each with a design capacity exceeding 10,000 m3 d(-1), and analyzed the corresponding effluent composition. 'Potential recycling percentage', R, ranged from 50% to 80% for the industrial park WWTPs, indicating a high feasibility for the reuse of effluent. In phase 2, a 50 m3 d(-1) pilot plant was installed in one of the selected WWTPs and underwent testing for one year. The quality of the reclaimed water was suitable for general-purpose industrial use. In the two ultrafiltration (UF) modules tested, the hydrophilic polyethersulfone hollow-fibre module was more tolerant to variable properties, and had higher recycling percentages than those of backwashable hydrophobic polyvinylidene difluoride spiral-wound module. Using the spiral-wound UF module helped reduce the cost for producing 1 m3 of reclaimed water (US$0.80) compared with a hollow-fibre module (US$0.88). In phase 3, we evaluated the negative effects of refluxing the reverse osmosis retentate, containing high total dissolved solids and non-biodegradable organics, with the biological treatment unit of the upstream WWTP. Biological compactibility tests showed that the refluxed retentate ratio should be reduced to maintain the conductivity of mixed liquor in the aeration tank at less than 110% of the original value.

  14. Optimizing Hollow Fibre Nanofiltration for Organic Matter Rich Lake Water

    Directory of Open Access Journals (Sweden)

    Alexander Keucken

    2016-09-01

    Full Text Available Over the years, various technologies have been utilized for Natural Organic Matter (NOM removal with varying degrees of success. Conventional treatment methods comprising of coagulation, flocculation, sedimentation, or filtration are widely used to remove NOM. An alternative to these conventional methods is to use spiral wound membranes. These membranes tend to remove too much hardness whilst being ineffective in disinfection. They also have a low tolerance to chlorine and thus, have limited chemical cleaning options. In this study, we investigated how an alternative and new innovative filtration concept, based on capillary NF membranes from modified polyethersulfone (PES, may be used to treat soft but humus-rich surface waters. Comprehensive performance tests, with a fully automated membrane pilot equipped with a full-scale sized test module (40 m2 membrane surface, were conducted at WTP Görvälnverket, which is operated by the water utility Norrvatten, providing drinking water from Mälaren (SUVA = 2.7–3.3, TOC = 7.0–10.0 mg·L−1 for about 500,000 people in the northern part of the Swedish capital of Stockholm. The removal of both UV and DOC was modeled using a solution diffusion approach. The optimized parameters allow deducing optimal operation conditions with respect to energy, water consumption, and permeate water quality. Optimal cross flow velocity was determined to be 0.75 m·s−1 at 80% recovery and a flux of 12–18 L·m−2·h−1. Under these conditions, 80% of the UV, 75% of the Humic Substances (MW = 600 and 70% of TOC were removed (from 8 to below 2 mg·L−1. A higher cross flow velocity led to marginal improvement (+2% while both higher and lower membrane fluxes degraded permeate water quality. Apparent optimized diffusion coefficients for UV and TOC were around 1.2–2.4 × 10−10·m2·s−1 and were similar to values found in the literature. Due to their higher diffusion coefficients and higher permeability

  15. Three-dimensional porous hollow fibre copper electrodes for efficient and high-rate electrochemical carbon dioxide reduction

    NARCIS (Netherlands)

    Kas, Recep; Hummadi, Khalid Khazzal; Kortlever, Ruud; de Wit, Patrick; Milbrat, Alexander; Luiten-Olieman, Maria W.J.; Benes, Nieck Edwin; Koper, Marc T.M.; Mul, Guido

    2016-01-01

    Aqueous-phase electrochemical reduction of carbon dioxide requires an active, earth-abundant electrocatalyst, as well as highly efficient mass transport. Here we report the design of a porous hollow fibre copper electrode with a compact three-dimensional geometry, which provides a large area,

  16. LHCb Scintillating Fibre Tracker Engineering Design Review Report: Fibres, Mats and Modules

    CERN Document Server

    Joram, Christian; Leverington, Blake Dean; Kirn, Thomas; Bachmann, Sebastian; Ekelhof, Robert Jan; Müller, Janine

    2015-01-01

    During the Long Shutdown 2 of the LHC, the LHCb collaboration will replace the current Outer and Inner Tracker by a single tracking detector, based on 2.42m long scintillating fibres with a diameter of 250 $\\mu$m, readout by silicon photo-multipliers (SiPM). The fibers are arranged in mats of 6 fibre-layers with a width of 130.65 mm. Eight fibre mats will form a module and are sandwiched between honeycomb and carbon fibre composite panels to provide stability and support over the module length of 4.85m. At either end of the module are the interfaces to the SiPMs and the front-end electronics. The active detection area of the Scintillating Fiber Tracker (SciFi) of 360m$^2$ will comprise 144 single modules arranged in 12 detection planes. This document summarizes the engineering design of the fibre mats and of the modules including the interfaces to the SiPMs and the mounting to the detector frames. Mechanical and detector properties of several prototype modules are discussed. The production procedure of the fi...

  17. Flexural stiffness of the composite steel and fibre-reinforced concrete circular hollow section column

    Science.gov (United States)

    Tretyakov, A.; Tkalenko, I.; Wald, F.; Novak, J.; Stefan, R.; Kohoutková, A.

    2017-09-01

    The recent development in technology of production and transportation of steel fibre-reinforced concrete enables its utilization in composite steel-concrete structures. This work is a part of a project which focuses on development of mechanical behaviour of circular hollow section (CHS) composite steel and fibre-concrete (SFRC) columns at elevate temperature. Research includes two levels of accuracy/complexity, allowing simplified or advanced approach for design that follows upcoming changes in European standard for composite member design in fire EN1994-1-2 [1]. One part is dedicated to determination and description of flexural stiffness of the SFRC CHS columns. To determinate flexural stiffness were prepared series of pure bending tests at elevated and ambient temperature. Presented paper focuses on the results of the tests and determination of flexural stiffness at ambient temperature. Obtained outputs were compared to data of existing studies about concrete-filled tube members with plain concrete and values analytically calculated according to the existing European standard EN1994-1-1 [2].

  18. Optimising cell aggregate expansion in a perfused hollow fibre bioreactor via mathematical modelling.

    Directory of Open Access Journals (Sweden)

    Lloyd A C Chapman

    Full Text Available The need for efficient and controlled expansion of cell populations is paramount in tissue engineering. Hollow fibre bioreactors (HFBs have the potential to meet this need, but only with improved understanding of how operating conditions and cell seeding strategy affect cell proliferation in the bioreactor. This study is designed to assess the effects of two key operating parameters (the flow rate of culture medium into the fibre lumen and the fluid pressure imposed at the lumen outlet, together with the cell seeding distribution, on cell population growth in a single-fibre HFB. This is achieved using mathematical modelling and numerical methods to simulate the growth of cell aggregates along the outer surface of the fibre in response to the local oxygen concentration and fluid shear stress. The oxygen delivery to the cell aggregates and the fluid shear stress increase as the flow rate and pressure imposed at the lumen outlet are increased. Although the increased oxygen delivery promotes growth, the higher fluid shear stress can lead to cell death. For a given cell type and initial aggregate distribution, the operating parameters that give the most rapid overall growth can be identified from simulations. For example, when aggregates of rat cardiomyocytes that can tolerate shear stresses of up to 0:05 Pa are evenly distributed along the fibre, the inlet flow rate and outlet pressure that maximise the overall growth rate are predicted to be in the ranges 2.75 x 10(-5 m(2 s(-1 to 3 x 10(-5 m(2 s(-1 (equivalent to 2.07 ml min(-1 to 2.26 ml min(-1 and 1.077 x 10(5 Pa to 1.083 x 10(5 Pa (or 15.6 psi to 15.7 psi respectively. The combined effects of the seeding distribution and flow on the growth are also investigated and the optimal conditions for growth found to depend on the shear tolerance and oxygen demands of the cells.

  19. Optimising cell aggregate expansion in a perfused hollow fibre bioreactor via mathematical modelling.

    KAUST Repository

    Chapman, Lloyd A C

    2014-08-26

    The need for efficient and controlled expansion of cell populations is paramount in tissue engineering. Hollow fibre bioreactors (HFBs) have the potential to meet this need, but only with improved understanding of how operating conditions and cell seeding strategy affect cell proliferation in the bioreactor. This study is designed to assess the effects of two key operating parameters (the flow rate of culture medium into the fibre lumen and the fluid pressure imposed at the lumen outlet), together with the cell seeding distribution, on cell population growth in a single-fibre HFB. This is achieved using mathematical modelling and numerical methods to simulate the growth of cell aggregates along the outer surface of the fibre in response to the local oxygen concentration and fluid shear stress. The oxygen delivery to the cell aggregates and the fluid shear stress increase as the flow rate and pressure imposed at the lumen outlet are increased. Although the increased oxygen delivery promotes growth, the higher fluid shear stress can lead to cell death. For a given cell type and initial aggregate distribution, the operating parameters that give the most rapid overall growth can be identified from simulations. For example, when aggregates of rat cardiomyocytes that can tolerate shear stresses of up to 0:05 Pa are evenly distributed along the fibre, the inlet flow rate and outlet pressure that maximise the overall growth rate are predicted to be in the ranges 2.75 x 10(-5) m(2) s(-1) to 3 x 10(-5) m(2) s(-1) (equivalent to 2.07 ml min(-1) to 2.26 ml min(-1)) and 1.077 x 10(5) Pa to 1.083 x 10(5) Pa (or 15.6 psi to 15.7 psi) respectively. The combined effects of the seeding distribution and flow on the growth are also investigated and the optimal conditions for growth found to depend on the shear tolerance and oxygen demands of the cells.

  20. Laser breakdown with millijoule trains of picosecond pulses transmitted through a hollow-core photonic-crystal fibre

    CERN Document Server

    Konorov, S O; Kolevatova, O A; Beloglasov, V I; Skibina, N B; Shcherbakov, A V; Wintner, E; Zheltikov, A M

    2003-01-01

    Sequences of picosecond pulses with a total energy in the pulse train of about 1 mJ are transmitted through a hollow-core photonic-crystal fibre with a core diameter of approximately 14 mu m. The fluence of laser radiation coupled into the core of the fibre under these conditions exceeds the breakdown threshold of fused silica by nearly an order of magnitude. The laser beam coming out of the fibre is then focused to produce a breakdown on a solid surface. Parameters of laser radiation were chosen in such a way as to avoid effects related to the excitation of higher order waveguide modes and ionization of the gas filling the fibre in order to provide the possibility to focus the output beam into a spot with a minimum diameter, thus ensuring the maximum spatial resolution and the maximum power density in the focal spot.

  1. Hollow-Fibre-Supported Dispersive Liquid-Liquid Microextraction for Determination of Atrazine and Triclosan in Aqueous Samples

    OpenAIRE

    Letseka, Thabiso; George, Mosotho J.

    2017-01-01

    We report the application of the dispersive liquid-liquid microextraction coupled to hollow-fibre membrane-assisted liquid-phase microextraction and its application for extraction of atrazine and triclosan. Under optimum conditions, namely, 25 μL of a 1 : 4 chlorobenzene : ethyl acetate mixture dispersed in 1 mL of aqueous sample, 10% (m/v) NaCl, a magnetic stirrer speed at 600 rpm, and 10 minutes' extraction time with toluene-filled fibre as the acceptor phase, the method demonstrates suffic...

  2. Polyethersulfone-based ultrafiltration hollow fibre membrane for drinking water treatment systems

    Science.gov (United States)

    Chew, Chun Ming; Ng, K. M. David; Ooi, H. H. Richard

    2017-12-01

    Conventional media/sand filtration has been the mainstream water treatment process for most municipal water treatment plants in Malaysia. Filtrate qualities of conventional media/sand filtration are very much dependent on the coagulation-flocculation process prior to filtration and might be as high as 5 NTU. However, the demands for better quality of drinking water through public piped-water supply systems are growing. Polymeric ultrafiltration (UF) hollow fibre membrane made from modified polyethersulfone (PES) material is highly hydrophilic with high tensile strength and produces excellent quality filtrate of below 0.3 NTU in turbidity. This advanced membrane filtration material is also chemical resistance which allows a typical lifespan of 5 years. Comparisons between the conventional media/sand filtration and PES-based UF systems are carried out in this paper. UF has been considered as the emerging technology in municipal drinking water treatment plants due to its consistency in producing high quality filtrates even without the coagulation-flocculation process. The decreasing cost of PES-based membrane due to mass production and competitive pricing by manufacturers has made the UF technology affordable for industrial-scale water treatment plants.

  3. Oblique crushing performances of hybrid woven Kenaf fibre reinforced aluminium hollow cylinder

    Directory of Open Access Journals (Sweden)

    Ismail Al Emran

    2017-01-01

    Full Text Available This paper presents crushing performances of hybrid woven kenaf fibre reinforced aluminium tubes under axial and oblique compression. According to open literature, lack number of works conducted to study the crushing responses when kenaf fibre in the form of woven is used to reinforce aluminium tubes. There are important parameters are used such as fibre orientations and oblique compression angles. Kenaf fibre in the form of woven is firstly wetted with polyester resin before it is wrapped around the tubes. After composite hardened, the hybrid tubes are quasi-statically compressed and force-displacement curves are recorded. Energy absorption performances are then determined and discussed in term of different fibre orientations and oblique angles. It is found that [±30°] fibre orientations capable to produce higher force-displacement responses and hybrid tubes are produced lower force ratio indicating the role of natural fibre in increasing the capability of energy absorptions.

  4. Upgrading coagulation with hollow-fibre nanofiltration for improved organic matter removal during surface water treatment.

    Science.gov (United States)

    Köhler, Stephan J; Lavonen, Elin; Keucken, Alexander; Schmitt-Kopplin, Philippe; Spanjer, Tom; Persson, Kenneth

    2016-02-01

    Rising organic matter concentrations in surface waters in many Nordic countries require current drinking water treatment processes to be adapted. Accordingly, the use of a novel nanofiltration (NF) membrane was studied during a nine month period in pilot scale at a large drinking water treatment plant in Stockholm, Sweden. A chemically resistant hollow-fibre NF membrane was fed with full scale process water from a rapid sand filter after aluminum sulfate coagulation. The combined coagulation and NF process removed more than 90% of the incoming lake water dissolved organic carbon (DOC) (8.7 mg C L(-1)), and 96% of the absorbance at 254 nm (A254) (0.28 cm(-1) incoming absorbance). Including granulated active carbon GAC) filter, the complete pilot plant treatment process we observed decreases in DOC concentration (8.7-0.5 mg C L(-1)), SUVA (3.1-1.7 mg(-1) L m(-1)), and the average nominal molecular mass (670-440 Da). Meanwhile, water hardness was practically unaffected (treatment was somewhat less selective but still preferentially targeted humic-like FDOM (83 ± 1%) to a larger extent than protein-like material (66 ± 3%). The high selectivity of organic matter during coagulation compared to NF separation was confirmed from analyses with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS), and liquid chromatography with organic carbon detection (LC-OCD), as coagulation exclusively targeted oxidized organic matter components while NF removed both chemically reduced and oxidized components. DOC removal and change in DOC character in the GAC filters showed marked differences with slower saturation and more pronounced shifts in DOC character using NF as pre-treatment. Fluorescence derived parameters showed a similar decrease over time of GAC performance for the first 150 days but also indicated ongoing change of DOM character in the post NF GAC filtrate over time even after LC-OCD indicated steady state with respect to outgoing carbon

  5. Hollow fibre membrane contactor as a gas-liquid model contactor

    NARCIS (Netherlands)

    Dindore, V.Y.; Brilman, Derk Willem Frederik; Versteeg, Geert

    2005-01-01

    Microporous hollow fiber gas–liquid membrane contactors have a fixed and well-defined gas–liquid interfacial area. The liquid flow through the hollow fiber is laminar, thus the liquid side hydrodynamics are well known. This allows the accurate calculation of the fiber side physical mass transfer

  6. Programmable logic controller optical fibre sensor interface module

    Science.gov (United States)

    Allwood, Gary; Wild, Graham; Hinckley, Steven

    2011-12-01

    Most automated industrial processes use Distributed Control Systems (DCSs) or Programmable Logic Controllers (PLCs) for automated control. PLCs tend to be more common as they have much of the functionality of DCSs, although they are generally cheaper to install and maintain. PLCs in conjunction with a human machine interface form the basis of Supervisory Control And Data Acquisition (SCADA) systems, combined with communication infrastructure and Remote Terminal Units (RTUs). RTU's basically convert different sensor measurands in to digital data that is sent back to the PLC or supervisory system. Optical fibre sensors are becoming more common in industrial processes because of their many advantageous properties. Being small, lightweight, highly sensitive, and immune to electromagnetic interference, means they are an ideal solution for a variety of diverse sensing applications. Here, we have developed a PLC Optical Fibre Sensor Interface Module (OFSIM), in which an optical fibre is connected directly to the OFSIM located next to the PLC. The embedded fibre Bragg grating sensors, are highly sensitive and can detect a number of different measurands such as temperature, pressure and strain without the need for a power supply.

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

    Science.gov (United States)

    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.

  8. Multiphase modelling of the influence of fluid flow and chemical concentration on tissue growth in a hollow fibre membrane bioreactor.

    Science.gov (United States)

    Pearson, Natalie C; Shipley, Rebecca J; Waters, Sarah L; Oliver, James M

    2014-12-01

    A 2D model is developed for fluid flow, mass transport and cell distribution in a hollow fibre membrane bioreactor. The geometry of the modelling region is simplified by excluding the exit ports at either end and focusing on the upper half of the central section of the bioreactor. Cells are seeded on a porous scaffold throughout the extracapillary space (ECS), and fluid pumped through the bioreactor via the lumen inlet and/or exit ports. In the fibre lumen and porous fibre wall, flow is described using Stokes and Darcy governing equations, respectively, while in the ECS porous mixture theory is used to model the cells, culture medium and scaffold. Reaction-advection-diffusion equations govern the concentration of a solute of interest in each region. The governing equations are reduced by exploiting the small aspect ratio of the bioreactor. This yields a coupled system for the cell volume fraction, solute concentration and ECS water pressure which is solved numerically for a variety of experimentally relevant case studies. The model is used to identify different regimes of cell behaviour, and results indicate how the flow rate can be controlled experimentally to generate a uniform cell distribution under regimes relevant to nutrient- and/or chemotactic-driven behaviours. © The Authors 2013. Published by Oxford University Press on behalf of the Institute of Mathematics and its Applications. All rights reserved.

  9. Multimode laser emission from dye-doped hollow polymer optical fibre

    Indian Academy of Sciences (India)

    2014-02-09

    Feb 9, 2014 ... tion of Rh B-doped methyl methacrylate (MMA). Hole in the preform can be achieved by placing a teflon rod on the centre of the glass tube during the polymerization. Final fibre structure with required diameter was obtained by heat drawing process. The diam- eter of the final fibre structure can be controlled ...

  10. Effect of internal pressure and gas/liquid interface area on the CO mass transfer coefficient using hollow fibre membranes as a high mass transfer gas diffusing system for microbial syngas fermentation.

    Science.gov (United States)

    Yasin, Muhammad; Park, Shinyoung; Jeong, Yeseul; Lee, Eun Yeol; Lee, Jinwon; Chang, In Seop

    2014-10-01

    This study proposed a submerged hollow fibre membrane bioreactor (HFMBR) system capable of achieving high carbon monoxide (CO) mass transfer for applications in microbial synthesis gas conversion systems. Hydrophobic polyvinylidene fluoride (PVDF) membrane fibres were used to fabricate a membrane module, which was used for pressurising CO in water phase. Pressure through the hollow fibre lumen (P) and membrane surface area per unit working volume of the liquid (A(S)/V(L)) were used as controllable parameters to determine gas-liquid volumetric mass transfer coefficient (k(L)a) values. We found a k(L)a of 135.72 h(-1) when P was 93.76 kPa and AS/VL was fixed at 27.5m(-1). A higher k(L)a of 155.16 h(-1) was achieved by increasing AS/VL to 62.5m(-1) at a lower P of 37.23 kPa. Practicality of HFMBR to support microbial growth and organic product formation was assessed by CO/CO2 fermentation using Eubacterium limosum KIST612. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. CO2 absorption at elevated pressures using a hollow fibre membrane contactor

    NARCIS (Netherlands)

    Dindore, V.Y.; Brilman, Derk Willem Frederik; Feron, P.H.M.; Versteeg, Geert

    2004-01-01

    Recently, hollow fiber membrane gas–liquid contactor-based processes have gained an increasing attention. Compared to conventional processes, these processes have numerous advantages. The membrane contactors provide a very high interfacial area per unit volume, independent regulation of gas and

  12. Hollow-Fibre-Supported Dispersive Liquid-Liquid Microextraction for Determination of Atrazine and Triclosan in Aqueous Samples

    Directory of Open Access Journals (Sweden)

    Thabiso Letseka

    2017-01-01

    Full Text Available We report the application of the dispersive liquid-liquid microextraction coupled to hollow-fibre membrane-assisted liquid-phase microextraction and its application for extraction of atrazine and triclosan. Under optimum conditions, namely, 25 μL of a 1 : 4 chlorobenzene : ethyl acetate mixture dispersed in 1 mL of aqueous sample, 10% (m/v NaCl, a magnetic stirrer speed at 600 rpm, and 10 minutes’ extraction time with toluene-filled fibre as the acceptor phase, the method demonstrates sufficient figures of merit. These include linearity (R2 ≥ 0.9975, intravial precision (%RSD ≤ 7.6, enrichment factors (127 and 142, limits of detection (0.0081 and 0.0169 µg/mL, and recovery from river water and sewerage (96–101%. The relatively high detection limits are attributed to the flame ionization detector which is less preferred than a mass spectrometer in trace analyses. This is the first report of a homogenous mixture of the dispersed organic solvent in aqueous solutions and its employment in extraction of organic compounds from aqueous solutions. It therefore adds yet another candidate in the pool of miniaturised solvent microextraction techniques.

  13. Economic comparison of transverse and longitudinal flow hollow fiber membrane modules for reverse osmosis and ultrafiltration

    NARCIS (Netherlands)

    Futselaar, H.; Zoontjes, R.J.C.; Reith, T.; Racz, I.G.

    1993-01-01

    The presently used hollow fiber membrane modules consist of a bundle of fibers in a cylindrical polymer or metal shell parallel to the shell axis. The feed solution flows either through the lumen or at the outside parallel to the fibers. This paper compares the performance of these modules with a

  14. Light and gas confinement in hollow-core photonic crystal fibre based photonic microcells

    DEFF Research Database (Denmark)

    Benabid, F.; Roberts, John; Couny, F.

    2009-01-01

    optical waveguide guidance. For the second type of fibre, which can guide over a broad wavelength range, we examine the nature of the inhibited coupling. We describe a technique for the fabrication of photonic microcells that can accommodate vacuum pressures, and we finish by showing the latest results...

  15. Air gap membrane distillation. 1. Modelling and mass transport properties for hollow fibre membranes

    NARCIS (Netherlands)

    Guijt, C.M.; Meindersma, G.W.; Reith, T.; de Haan, A.B.

    2005-01-01

    A predictive model for air gap membrane distillation in a counter current flow configuration using fibre membranes is presented. The water vapour transport across the membrane is described by the dusty-gas model that uses constant membrane mass transport parameters to describe simultaneous Knudsen

  16. Liquid-phase membrane extraction of targeted pesticides from manufacturing wastewaters in a hollow fibre contactor with feed-stream recycle.

    Science.gov (United States)

    Đorđević, Jelena; Vladisavljević, Goran T; Trtić-Petrović, Tatjana

    2017-01-01

    A two-phase membrane extraction in a hollow fibre contactor with feed-stream recycle was applied to remove selected pesticides (tebufenozide, linuron, imidacloprid, acetamiprid and dimethoate) from their mixed aqueous solutions. The contactor consisted of 50 polypropylene hollow fibres impregnated with 5% tri-n-octylphosphine oxide in di-n-hexyl ether. For low-polar pesticides with log P ≥ 2 (tebufenozide and linuron), the maximum removal efficiency increased linearly from 85% to 96% with increasing the feed flow rate. The maximum removal efficiencies of more polar pesticides were significantly higher under feed recirculation (86%) than in a continuous single-pass operation (30%). It was found from the Wilson's plot that the mass transfer resistance of the liquid membrane can be neglected for low-polar pesticides. The pesticide removals from commercial formulations were similar to those from pure pesticide solutions, indicating that built-in adjuvants did not affect the extraction process.

  17. Rapid analysis of phthalates in beverage and alcoholic samples by multi-walled carbon nanotubes/silica reinforced hollow fibre-solid phase microextraction.

    Science.gov (United States)

    Li, Jia; Su, Qiong; Li, Ke-Yao; Sun, Chu-Feng; Zhang, Wen-Bo

    2013-12-15

    A novel procedure based on multi-walled carbon nanotubes (MWCNTs)/silica reinforced hollow fibre solid-phase microextraction combined with gas chromatography-mass spectrometry has been developed to analyse trace phthalate acid esters in beverage and alcoholic samples. Because of their excellent adsorption capability towards hydrophobic compounds, functionalized MWCNTs, acting as solid-phase sorbent, were co-deposited with silica particles in the pores of polypropylene hollow fibre through a layer-by-layer self-assembly technique. The parameters influencing the extraction efficiency, such as pH values and ionic strength of sample solution, extraction time, temperature and desorption solvent were optimised. Recoveries for phthalates at spiking levels in different matrices were satisfactory (between 68% and 115%). Moreover, the results were further confirmed by comparing them with those obtained using a solvent extraction method according to the national standard of China. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. Surface modification of poly(vinylidene fluoride) hollow fibre membranes for biogas purification in a gas–liquid membrane contactor system

    Science.gov (United States)

    Huang, Chuan; Li, Jiaxiang; Shen, Yadong; Wang, Liao

    2017-01-01

    The wetting of hollow fibre membranes decreases the performance of the liquid–gas membrane contactor for CO2 capture in biogas upgrading. To solve this problem, in this work, a poly(vinylidene fluoride) (PVDF) hollow fibre membrane for a liquid–gas membrane contactor was coated with a superhydrophobic layer composed of a combination of hydrophobic SiO2 nanoparticles and polydimethylsiloxane (PDMS) by the method of spray deposition. A rough layer of SiO2 deposited on the PVDF membrane resulted in an enhanced surface hydrophobicity. The surface structure of the pristine PVDF significantly affected the homogeneity of the generated SiO2 layer. A uniform surface coating on the PVDF upper layer resulted from the presence of micrometre and nanometre-sized roughness on the surface of the PVDF membrane, which was achieved with a SiO2 concentration of 4.44 mg ml−1 (0.2 g/45 ml) in the coating solution. As a result, the water contact angle of the modified surface was recorded as 155 ± 3°, which is higher than that of the pristine surface. The high contact angle is advantageous for reducing the wetting of the membrane. Additional mass transfer resistance was introduced by the superhydrophobic layer. In addition, continuous CO2 absorption tests were carried out in original and modified PVDF hollow fibre membrane contactors, using monoethanolamine (MEA) solution as the absorbent. A long-term stability test revealed that the modified PVDF hollow fibre membrane contactor was able to outperform the original membrane contactor and demonstrated outstanding long-term stability, suggesting that spray deposition is a promising approach to obtain superhydrophobic PVDF membranes for liquid–gas membrane absorption. PMID:29291117

  19. Surface modification of poly(vinylidene fluoride) hollow fibre membranes for biogas purification in a gas-liquid membrane contactor system.

    Science.gov (United States)

    Jin, Pengrui; Huang, Chuan; Li, Jiaxiang; Shen, Yadong; Wang, Liao

    2017-11-01

    The wetting of hollow fibre membranes decreases the performance of the liquid-gas membrane contactor for CO 2 capture in biogas upgrading. To solve this problem, in this work, a poly(vinylidene fluoride) (PVDF) hollow fibre membrane for a liquid-gas membrane contactor was coated with a superhydrophobic layer composed of a combination of hydrophobic SiO 2 nanoparticles and polydimethylsiloxane (PDMS) by the method of spray deposition. A rough layer of SiO 2 deposited on the PVDF membrane resulted in an enhanced surface hydrophobicity. The surface structure of the pristine PVDF significantly affected the homogeneity of the generated SiO 2 layer. A uniform surface coating on the PVDF upper layer resulted from the presence of micrometre and nanometre-sized roughness on the surface of the PVDF membrane, which was achieved with a SiO 2 concentration of 4.44 mg ml -1 (0.2 g/45 ml) in the coating solution. As a result, the water contact angle of the modified surface was recorded as 155 ± 3°, which is higher than that of the pristine surface. The high contact angle is advantageous for reducing the wetting of the membrane. Additional mass transfer resistance was introduced by the superhydrophobic layer. In addition, continuous CO 2 absorption tests were carried out in original and modified PVDF hollow fibre membrane contactors, using monoethanolamine (MEA) solution as the absorbent. A long-term stability test revealed that the modified PVDF hollow fibre membrane contactor was able to outperform the original membrane contactor and demonstrated outstanding long-term stability, suggesting that spray deposition is a promising approach to obtain superhydrophobic PVDF membranes for liquid-gas membrane absorption.

  20. Xanthan GumRecovery from Palm Oil-Based Fermentation Broth by Hollow Fibre Microfiltration (MF) Membrane with ProcessOptimisation Using Taguchi Method

    OpenAIRE

    Sufian Soaib, M.; M. Sabet; Krishnan, J.; VPS Veluri, M.

    2013-01-01

    First stage Xanthan recovery (cell and oil separation) from palm oil-based fermentation broth was carried out by hollow fibre microfiltration (MF) using Taguchi method as design of experiment (DOE) to study the effect of four main parameters on Xanthan recovery; transmembrane pressure (TMP), crossflow velocity (CFV), ionic strength (IS) and temperature (T). From S/N ratio larger-the-better analysis, optimum conditions for Xanthan recovery were at level 2 of TMP, IS and T respectively and leve...

  1. Digital coherent receiver for subcarrier multiplexed phase modulated radio-over-fibre signals

    DEFF Research Database (Denmark)

    Zibar, Darko; Larsen, Knud J.; Tafur Monroy, Idelfonso

    2009-01-01

    Digital coherent detection of multi-channel subcarrier multiplexed optically phase-modulated radio-over-fibre signals is experimentally demonstrated. Successful detection after transmission over a 40 km long fibre link of four or five 25 Mbaud BPSK/QPSK subcarrier channels in 5 GHz bandwidth...... is demonstrated using offline digital signal processing....

  2. Large-scale progenitor cell expansion for multiple donors in a monitored hollow fibre bioreactor.

    Science.gov (United States)

    Lambrechts, Toon; Papantoniou, Ioannis; Rice, Brent; Schrooten, Jan; Luyten, Frank P; Aerts, Jean-Marie

    2016-09-01

    With the increasing scale in stem cell production, a robust and controlled cell expansion process becomes essential for the clinical application of cell-based therapies. The objective of this work was the assessment of a hollow fiber bioreactor (Quantum Cell Expansion System from Terumo BCT) as a cell production unit for the clinical-scale production of human periosteum derived stem cells (hPDCs). We aimed to demonstrate comparability of bioreactor production to standard culture flask production based on a product characterization in line with the International Society of Cell Therapy in vitro benchmarks and supplemented with a compelling quantitative in vivo bone-forming potency assay. Multiple process read-outs were implemented to track process performance and deal with donor-to-donor-related variation in nutrient needs and harvest timing. The data show that the hollow fiber bioreactor is capable of robustly expanding autologous hPDCs on a clinical scale (yield between 316 million and 444 million cells starting from 20 million after ± 8 days of culture) while maintaining their in vitro quality attributes compared with the standard flask-based culture. The in vivo bone-forming assay on average resulted in 10.3 ± 3.7% and 11.0 ± 3.8% newly formed bone for the bioreactor and standard culture flask respectively. The analysis showed that the Quantum system provides a reproducible cell expansion process in terms of yields and culture conditions for multiple donors. Copyright © 2016 International Society for Cellular Therapy. Published by Elsevier Inc. All rights reserved.

  3. Monitoring of N-methyl carbamate pesticide residues in water using hollow fibre supported liquid membrane and solid phase extraction

    Science.gov (United States)

    Msagati, Titus A. M.; Mamba, Bhekie B.

    The aim of this work was to develop a method for the determination of N-methyl carbamates in water involving hollow fibre supported liquid membrane (HFSLM) and solid phase extraction (SPE) as sample preparation methods. Four N-methyl carbamate pesticides, aldicarb, carbaryl, carbofuran and methiocarb sulfoxide, were simultaneously extracted and analysed by a liquid chromatograph with a diode array detector (LC-UV/DAD) and a liquid chromatograph coupled to a ion trap quadrupole mass spectrometer (LC-ESI-MS). The high performance liquid chromatography (HPLC) separation of carabamate extracts was performed on a C18 column with water-acetonitrile as the mobile phase. The mass spectrometry analyses were carried out in the positive mode, operating under both the selected ion monitoring (SIM) and full scan modes. The solid phase recoveries of the extracts ranged between 8% and 98%, with aldicarb having the highest recoveries, followed by carbaryl, carbofuran and methiocarb had the lowest recovery. The HFSLM recovery ranged between 8% and 58% and the order of recovery was similar to the SPE trend. Factors controlling the efficiency of the HFSLM extraction such as sample pH, stripping phase pH, enrichment time, stirring speed as well as organic solvent used for entrapment of analytes, were optimised to achieve the highest enrichment factors.

  4. Feasibility study of Zeeman modulation spectrometry with a hollow capillary fiber based gas cell.

    Science.gov (United States)

    Hangauer, Andreas; Chen, Jia; Strzoda, Rainer; Amann, Markus-Christian

    2012-04-01

    For paramagnetic gases (e.g., O2, NO, NO2, OH) Zeeman modulation spectrometry is a method for spectrometric gas sensing with extraordinary selectivity. In this Letter it is combined with a hollow capillary based gas cell, where the gas is filled in long light-guiding capillary that is placed inside a toroidal coil. Over conventional Zeeman spectrometry this has the advantage of lower power consumption at long optical path length, since several loops of the hollow capillary fiber can be placed in the coil. Compared to wavelength modulation spectrometry the advantage is insensitivity to interference by multimode propagation in the fiber and absorption by other nonparamagnetic gases, which should enhance both sensor stability and sensitivity. Experimental and theoretical results are presented, showing the feasibility of the approach.

  5. Numerical Study on Flow Characteristics of Hollow Fiber Membrane Module for Water Recovery Cooling Tower

    Energy Technology Data Exchange (ETDEWEB)

    Park, Chang Cheol; Shin, Weon Gyu [Chungnam Nat’l Univ., Daejeon (Korea, Republic of); Park, Hyun Seol; Lee, Hyung Keun [Korea Institute of Energy Research, Daejeon (Korea, Republic of)

    2017-08-15

    The purpose of this study is to analyze the flow characteristics when a staggered hollow fiber membrane module is modeled as a porous medium. The pressure-velocity equation was used for modeling the porous medium, using pressure drop data. In terms of flow characteristics, we compared the case of the 'porous medium' when the membrane module was modeled as a porous medium with the case of the 'membrane module' when considering the original shape of the membrane module. The difference in pressure drop between the 'porous medium' and 'membrane module' was less than 0.6%. However, the maximum flow velocity and mean turbulent kinetic energy of the 'porous medium' were 2.5 and 95 times larger than those of the 'membrane module,' respectively. Our results indicate that modeling the hollow fiber module as a porous medium is useful for predicting pressure drop, but not sufficient for predicting the maximum flow velocity and mean turbulent kinetic energy.

  6. Thermally moderated hollow fiber sorbent modules in rapidly cycled pressure swing adsorption mode for hydrogen purification

    KAUST Repository

    Lively, Ryan P.

    2012-10-01

    We describe thermally moderated multi-layered pseudo-monolithic hollow fiber sorbents entities, which can be packed into compact modules to provide small-footprint, efficient H2 purification/CO2 removal systems for use in on-site steam methane reformer product gas separations. Dual-layer hollow fibers are created via dry-jet, wet-quench spinning with an inner "active" core of cellulose acetate (porous binder) and zeolite NaY (69 wt% zeolite NaY) and an external sheath layer of pure cellulose acetate. The co-spun sheath layer reduces the surface porosity of the fiber and was used as a smooth coating surface for a poly(vinyl-alcohol) post-treatment, which reduced the gas permeance through the fiber sorbent by at least 7 orders of magnitude, essentially creating an impermeable sheath layer. The interstitial volume between the individual fibers was filled with a thermally-moderating paraffin wax. CO2 breakthrough experiments on the hollow fiber sorbent modules with and without paraffin wax revealed that the "passively" cooled paraffin wax module had 12.5% longer breakthrough times than the "non-isothermal" module. The latent heat of fusion/melting of the wax offsets the released latent heat of sorption/desorption of the zeolites. One-hundred rapidly cycled pressure swing adsorption cycles were performed on the "passively" cooled hollow fiber sorbents using 25 vol% CO2/75 vol% He (H2 surrogate) at 60 °C and 113 psia, resulting in a product purity of 99.2% and a product recovery of 88.1% thus achieving process conditions and product quality comparable to conventional pellet processes. Isothermal and non-isothermal dynamic modeling of the hollow fiber sorbent module and a traditional packed bed using gPROMS® indicated that the fiber sorbents have sharper fronts (232% sharper) and longer adsorbate breakthrough times (66% longer), further confirming the applicability of the new fiber sorbent approach for H2 purification. © 2012, Hydrogen Energy Publications, LLC

  7. Design and fabrication of inner-selective thin-film composite (TFC) hollow fiber modules for pressure retarded osmosis (PRO)

    KAUST Repository

    Wan, Chun Feng

    2016-08-03

    Pressure retarded osmosis (PRO) is a promising technology to harvest the renewable osmotic energy from salinity gradients. There are great progresses in the fabrication of PRO membranes in the last decade. Thin-film composite (TFC) hollow fibers have been widely studied and demonstrated superior performance. However, the lack of effective TFC hollow fiber modules hinders the commercialization of the PRO technology. Knowledge and experiences to fabricate TFC hollow fiber modules remain limited in the open literature. In this study, we aim to reveal the engineering and science on how to fabricate TFC hollow fiber modules including the formation of inner-selective polyamide layers and the repair of leakages. TFC-PES hollow fiber modules with 30% and 50% packing densities have been successfully fabricated, showing peak power densities of 20.0 W/m2 and 19.4 W/m2, respectively, at 20 bar using 1 M NaCl solution and DI water as feeds. The modules may be damaged during handling and high pressure testing. The repaired modules have a power density of 18.2 W/m2, 91% of the power densities of the undamaged ones. This study would make up the gap between TFC membrane fabrication and TFC membrane module fabrication in the membrane industry. © 2016 Elsevier B.V.

  8. Bench scale model studies on sanitary landfill leachate treatment with M. oleifera seed extract and hollow fibre micro-filtration membrane

    Directory of Open Access Journals (Sweden)

    S. A. Muyibi

    2002-10-01

    Full Text Available A laboratory-based study using a Bench Scale model of four unit operations made up of coagulation (using Moringa oleifera seed extract as a coagulant, flocculation, sedimentation and micro-filtration, have been adopted to treat the leachate from Air Hitman Sanitary Landfill at Puchong in Malaysia. M. oleifera dosages of 150 and 175 mg/L had achieved 43.8% Cadmium removal, 21.2% Total Chromium removal, 66.8% Lead removal and 16% Iron removal. It also removed 55.4% of Total Suspended Solids, 10% of Total Dissolved Solids and 24.2% of Volatile Suspended Solids. Micro-filtration hollow fibre membrane decreased the turbidity, total suspended solids, total dissolved solids, volatile suspended solids, and organic matter in the leachate by 98.3%, 96.7%, 20.8%, 36.6% and 21.9% respectively. Overall heavy metals removal after micro-filtration using hollow fibre membrane was 94% for Cadmium, 29.8% for Total Chromium, 73.2% for Lead, and 18.3% for Iron. The results have shown that M. oleifera is a promising natural polymer for removing heavy metals from leachates and may be used as a pre-treatment to eliminate a portion of the toxic heavy metals, which limits the activity of micro organisms in the leachates.

  9. Precision 3-D microscopy with intensity modulated fibre optic scanners

    Science.gov (United States)

    Olmos, P.

    2016-01-01

    Optical 3-D imagers constitute a family of precision and useful instruments, easily available on the market in a wide variety of configurations and performances. However, besides their cost they usually provide an image of the object (i.e. a more or less faithful representation of the reality) instead of a truly object's reconstruction. Depending on the detailed working principles of the equipment, this reconstruction may become a challenging task. Here a very simple yet reliable device is described; it is able to form images of opaque objects by illuminating them with an optical fibre and collecting the reflected light with another fibre. Its 3-D capability comes from the spatial filtering imposed by the fibres together with their movement (scanning) along the three directions: transversal (surface) and vertical. This unsophisticated approach allows one to model accurately the entire optical process and to perform the desired reconstruction, finding that information about the surface which is of interest: its profile and its reflectance, ultimately related to the type of material.

  10. A simulation model for transient response of a gas separation module using a hollow fiber membrane

    Energy Technology Data Exchange (ETDEWEB)

    Sugiyama, Takahiko, E-mail: t-sugiyama@nucl.nagoya-u.ac.jp [Nagoya University, Fro-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Miyahara, Naoya [Nagoya University, Fro-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Tanaka, Masahiro [National Institute for Fusion Science, Oroshi-cho 322-6, Toki 509-5292 (Japan); Munakata, Kenzo [Akita University, Tegata Gakuen-cho 1-1, Akita-shi, Akita 010-8502 (Japan); Yamamoto, Ichiro [Nagoya University, Fro-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

    2011-10-15

    A simulation model has been developed for transient response of a gas separation module using a hollow fiber membrane for the removal of tritium from the atmosphere of the confinement space. The mass transfer process such as sorption and desorption of gases at the surface of the dense layer and the porous support layer, diffusive transfer in the both layers are treated in the model. Sorption isotherm, mass transfer rate and permeance are estimated through step-wise transient response experiments. The present model represents well not only separation factors and recovery ratio at the steady state but also responses to the multi-step wise change in the sweep gas rate.

  11. Elimination de l'auto-modulation de phase dans un amplificateur optique à fibre

    OpenAIRE

    Audo, Frederic; Boscolo, Sonia; Fatome, Julien; Kibler, Bertrand; Finot, Christophe

    2017-01-01

    Nous proposons et démontrons expérimentalement une nouvelle technique simple et efficace pour combattre l’auto-modulation de phase qui dégrade les performances des amplificateurs à fibre. En appliquant une modulation de phase temporelle sinusoïdale, nous éliminons ainsi quasi-totalement l’élargissement spectral causé par l’effet Kerr.

  12. Can the gastrointestinal microbiota be modulated by dietary fibre to treat obesity?

    Science.gov (United States)

    Davis, H C

    2017-10-16

    Recent research suggests that the human gastrointestinal microbiota is greatly involved in yielding, storing and expending energy from the diet; therefore, it may be a further factor in linking diet to obesity. The gut microbial composition is affected by diet throughout the human lifespan, and is highly dynamic and efficient in response to dietary alterations in particular to dietary fibre intake. Short-chained fatty acids (SCFA) are the bi-product of fibre fermentation and have both obesogenic and anti-obesogenic properties. The production of specific forms of SCFAs depends on the microbes available in the gut and the type of fibre ingested. The gut microbiome associated with healthy lean individuals has a higher microbial biodiversity and a greater Bacteroidete to Firmicute ratio compared to the obese individuals associated with microbiome. These gut microbial associations are similar to those seen in individuals with high and low dietary fibre intakes, respectively. Metabolites generated by Bacteroidetes and Firmicutes include the three main SCFA related to obesity, namely butyrate, acetate and propionate. However, neither Bacteroidetes nor Firmicutes is purely causative or purely preventative of obesity. More research is crucial in linking the various types of fibre with particular SCFA production and the microbiome it promotes before suggesting that dietary fibre modulation of the gut microbiome can treat obesity. However, the long-term dietary trend plays the principal role in assembling the diversity and abundance of gut microbes; thus, a sustained diet high in fibre may help prevent obesity by promoting a microbiome associated with a lean phenotype.

  13. Dietary fibres modulate the composition and activity of butyrate-producing bacteria in the large intestine of suckling piglets

    NARCIS (Netherlands)

    Mu, Chunlong; Zhang, Lingli; He, Xiangyu; Smidt, Hauke; Zhu, Weiyun

    2017-01-01

    Dietary fibres have been shown to affect early-life microbiota colonization in the large intestine of suckling piglets, however, much less is known as to whether they also modulate the composition and activity of butyrate-producing bacteria. Here, we investigated the effect of dietary fibres on the

  14. Suppression of Brillouin scattering in fibre-optical parametric amplifier by applying temperature control and phase modulation

    DEFF Research Database (Denmark)

    Lorenzen, Michael Rodas; Noordegraaf, Danny; Nielsen, Carsten Vandel

    2009-01-01

    An increased gain in a fibre-optical parametric amplifier through suppression of stimulated Brillouin scattering is demonstrated by applying a temperature distribution along the fibre for a fixed phase modulation of the pump. The temperature distribution slightly impacts the gain spectrum....

  15. In-line formation of chemically cross-linked P84® co-polyimide hollow fibre membranes for H2/CO2 separation

    KAUST Repository

    Choi, Seung Hak

    2010-12-13

    In this study, chemically cross-linked asymmetric P84® co-polyimide hollow fibre membranes with enhanced separation performance were fabricated, using a dry-wet spinning process with an innovative in-line cross-linking step. The chemical modification was conducted by controlled immersion of the coagulated fibre in an aqueous 1,5-diamino-2-methylpentane (DAMP) cross-linker solution before the take-up. The effect of the cross-linker concentration on the thermal, mechanical, chemical and gas transport properties of the membranes was investigated. FT-IR/ATR analysis was used to identify the chemical changes in the polymer, while DSC analysis confirmed the changes in the Tg and the specific heat of the polymer upon cross-linking. Chemical cross-linking with a 10 wt.% aqueous DAMP solution strongly enhanced the H2/CO2 ideal selectivity from 5.3 to 16.1, while the H2 permeance of the membranes decreased from 7.06 × 10−3 to 1.01 × 10−3 m3(STP) m−2 h−1 bar−1 for a feed pressure of 1 bar at 25 °C. The increase of selectivity with decreasing permeance is somewhat higher than the slope in the Robeson upper bound, evidencing the positive effect of the cross-linking on the separation performance of the fibres. Simultaneously, the cross-linking leads to improved mechanical resistance of the membranes, which could be further enhanced by an additional thermal treatment. The produced membranes are therefore more suitable for use under harsh conditions and have a better overall performance than the uncross-linked ones.

  16. Predicting optimal back-shock times in ultrafiltration hollow fiber modules II: Effect of inlet flow and concentration dependent viscosity

    DEFF Research Database (Denmark)

    Vinther, Frank; Pinelo, Manuel; Brøns, Morten

    2015-01-01

    This paper concerns mathematical modeling and computational fluid dynamics of back-shocking during hollow fibre ultrafiltration of dextran T500. In this paper we present a mathematical model based on first Principles, i.e., solving the Navier-Stokes equation along with the continuity equation...... fibre membranes, J. Membr. Sci. 470 (2014) 275-293 [33]).Furthermore, the simulations have been performed with two different inlet velocities, i.e., crossflow velocities and are clone with and without a concentration dependent viscosity. This enables us, for the first time, to investigate the effect...... in this paper.Furthermore, it is found that the optimal back-shock time increases when the viscosity is allowed to depend on the concentration It is found that this can be explained by a decrease in the velocity tangential to the membrane due to the increase in viscosity where the concentration is high...

  17. Polarization-multiplexed and phase-stepped fibre optic shearography using laser wavelength modulation

    Science.gov (United States)

    Groves, Roger M.; James, Stephen W.; Tatam, Ralph P.

    2000-09-01

    A shearography system that measures the deformation gradient using two orthogonal shear directions and performs phase stepping, using no moving mechanical components and a single CCD camera, is described. The light exiting from a highly linearly birefringent optical fibre is switched between two orthogonal linearly polarized states by tuning the optical wavelength of a laser diode via injection current modulation. A polarization sensitive Michelson interferometer is used to shear the image in orthogonal directions for p- and s-polarized light. The change in the optical wavelength is also used to provide a phase step in the pathlength imbalanced interferometer. In this way wavelength modulation of a laser diode source is used to accomplish simultaneously polarization multiplexing and phase stepping in the shearing interferometer. By carefully matching the optical wavelength shift, the optical fibre length and the pathlength imbalance in the interferometer, the π/2 polarization shift can be matched to the required phase step.

  18. Digital coherent receiver employing photonic downconversion for phase modulated radio-over-fibre links

    OpenAIRE

    Zibar, Darko; Caballero Jambrina, Antonio; Guerrero Gonzalez, Neil; Schaeffer, Christian; Tafur Monroy, Idelfonso

    2009-01-01

    A digital coherent receiver employing photonic downconversion is presented and experimentally demonstrated for phase-modulated radio-over-fibre optical links. The receiver is capable of operating at frequencies exceeding the bandwidth of electrical analog-to-digital converter by using photonic downconversion to translate the high-frequency input RF signal to the operating frequency range of the analog-to-digital converter. First, using linear digital demodulation scheme we measure SFDR of the...

  19. Towards a reduced chemistry module of a He-Ar-Cu hollow cathode discharge

    Science.gov (United States)

    Mihailova, D.; van Dijk, J.; Grozeva, M.; Degrez, G.; van der Mullen, J. J. A. M.

    2011-05-01

    This study is aimed at finding a reduced chemistry module for a hollow cathode discharge (HCD) excited in a He-Ar-Cu mixture. This enables us to construct lean and reliable models that can be used as a part of the design tool of HCDs. To this end estimative calculations and numerical simulations are performed under optimal conditions for lasing. An analysis of the species behaviour and reactions is made and as a result the model is simplified by means of reducing the number of species and reactions. The consequences of these reductions are justified by comparing the results of the simplified models with those of a more complete one. This study delivers a model that is chemically lean and thus, much less time consuming. It can be used in optimization studies to find the optimum in the plasma control parameter set of HCDs. The technique developed in this study for HCDs can be applied to glow discharges in general.

  20. Towards a reduced chemistry module of a He-Ar-Cu hollow cathode discharge

    Energy Technology Data Exchange (ETDEWEB)

    Mihailova, D; Van Dijk, J; Van der Mullen, J J A M [Department of Applied Physics, Eindhoven University of Technology, PO Box 513, 5600 MB, Eindhoven (Netherlands); Grozeva, M [Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee, 1784 Bulgaria (Bulgaria); Degrez, G, E-mail: diana@epgmod.phys.tue.nl [Service de Mecanique des Fluides, Universite Libre de Bruxelles, 50 avenue F.D. Roosevelt, 1050 Bruxelles (Belgium)

    2011-05-18

    This study is aimed at finding a reduced chemistry module for a hollow cathode discharge (HCD) excited in a He-Ar-Cu mixture. This enables us to construct lean and reliable models that can be used as a part of the design tool of HCDs. To this end estimative calculations and numerical simulations are performed under optimal conditions for lasing. An analysis of the species behaviour and reactions is made and as a result the model is simplified by means of reducing the number of species and reactions. The consequences of these reductions are justified by comparing the results of the simplified models with those of a more complete one. This study delivers a model that is chemically lean and thus, much less time consuming. It can be used in optimization studies to find the optimum in the plasma control parameter set of HCDs. The technique developed in this study for HCDs can be applied to glow discharges in general.

  1. Development and characterization of microfiltration hollow-fiber modules for sterilization of fermentation media

    Directory of Open Access Journals (Sweden)

    Faria L.F.F.

    2002-01-01

    Full Text Available Sterilization of fermentation medium involving heat may result in undesirable chemical reactions that alter nutrient concentration and yield products, which interfere in the fermentation performance. Sterilization of heat-sensitive compounds usually involves separate sterilizations of carbon source and nutrient solution. Membrane separation processes are an alternative to thermal processes, as they have many advantages such as the possibility of continuous and modular operation and the use of moderate temperatures. In this context, the objective of this work was the preparation of hollow-fiber membranes and the design of modules suitable for continuous sterilization of fermentation medium. The membrane with the best performance had a maximum pore diameter of 0.2 mu m and a permeability of 42.9 L/m².bar.h for a glucose/peptone/yeast extract medium. A module with 0.26 m² of permeation area was built with these membranes. This module was able to provide a permeate flow rate of 2.2 L/h using a pressure difference of 0.2 bar. The collected permeate was completely sterile, thus confirming the efficiency of this process.

  2. Predicting optimal back-shock times in ultrafiltration hollow fibre modules through path-lines

    DEFF Research Database (Denmark)

    Vinther, Frank; Pinelo, Manuel; Brøns, Morten

    2014-01-01

    as compared to the steady-state solution. Furthermore, the effect of changing different parameters such as inlet velocity, forward and backwards pressure on the back-shock time, the increase in volumetric flux and observed rejection, is presented. Moreover, two analytical estimates for the optimal back......-shock time derived from calculating the path-lines during a back-shock cycle are presented. Both of these expressions are in good agreement with the results obtained from the mathematical model and data collected from the literature. Based on this, a simple expression for an optimal back-shock time...

  3. High-speed ADC and DAC modules with fibre optic interconnections for telecom satellites

    Science.gov (United States)

    Heikkinen, Veli; Juntunen, Eveliina; Karppinen, Mikko; Kautio, Kari; Ollila, Jyrki; Sitomaniemi, Aila; Tanskanen, Antti; Casey, Rory; Scott, Shane; Gachon, Hélène; Sotom, Michel; Venet, Norbert; Toivonen, Jaakko; Tuominen, Taisto; Karafolas, Nikos

    2017-11-01

    The flexibility required for future telecom payloads calls for the introduction of more and more digital processing capabilities. Aggregate data throughputs of several Tbps will have to be handled onboard, thus creating the need for effective, ADCDSP and DACDSP highspeed links. ADC and DAC modules with optical interconnections is an attractive option as it can solve easily the transmission and routing of the expected huge amount of data. This technique will enable to increase the bandwidth and/or the number of beams/channels to be treated, or to support advanced digital processing architectures including beam forming. We realised electrooptic ADC and DAC modules containing an 8 bit, 2 GSa/s A/D converter and a 12 bit, 2 GSa/s D/A converter. The 4channel parallel fibre optic link employs 850nm VCSELs and GaAs PIN photodiodes coupled to 50/125μm fibre ribbon cable. ADCDSP and DSPDAC links both have an aggregate data rate of 25 Gbps. The paper presents the current status of this development.

  4. Digital coherent receiver employing photonic downconversion for phase modulated radio-over-fibre links

    DEFF Research Database (Denmark)

    Zibar, Darko; Caballero Jambrina, Antonio; Guerrero Gonzalez, Neil

    2009-01-01

    A digital coherent receiver employing photonic downconversion is presented and experimentally demonstrated for phase-modulated radio-over-fibre optical links. The receiver is capable of operating at frequencies exceeding the bandwidth of electrical analog-to-digital converter by using photonic...... downconversion to translate the high-frequency input RF signal to the operating frequency range of the analog-to-digital converter. First, using linear digital demodulation scheme we measure SFDR of the link at microwave frequency of 5 GHz. Thereafter, successful signal demodulation of 50 Mbit/s binary phase...... shift keying (BPSK) modulated data signal at 5 GHz RF carrier frequency is experimentally demonstrated by using an analog-to-digital converter with only 1 GHz bandwidth. We successfully demonstrate signal demodulation, using the proposed digital coherent receiver with photonic downconversion, after 40...

  5. Osmotic Power Generation by Inner Selective Hollow Fiber Membranes: An investigation of thermodynamics, mass transfer, and module scale modelling

    KAUST Repository

    Xiong, Jun Ying

    2016-12-29

    A comprehensive analysis of fluid motion, mass transport, thermodynamics and power generation during pressure retarded osmotic (PRO) processes was conducted. This work aims to (1) elucidate the fundamental relationship among various membrane properties and operation parameters and (2) analyse their individual and combined impacts on PRO module performance. A state-of-the-art inner-selective thin-film composite (TFC) hollow fiber membrane was employed in the modelling. The analyses of mass transfer and Gibbs free energy of mixing indicate that the asymmetric nature of hollow fibers results in more significant external concentration polarization (ECP) in the lumen side of the inner-selective hollow fiber membranes. In addition, a trade-off relationship exists between the power density (PD) and the specific energy (SE). The PD vs. SE trade-off upper bound may provide a useful guidance whether the flowrates of the feed and draw solutions should be further optimized in order to (1) minimize the boundary thickness and (2) maximize the osmotic power generation. Two new terms, mass transfer efficiency and power harvesting efficiency for osmotic power generation, have been proposed. This work may provide useful insights to design and operate PRO modules with enhanced performance so that the PRO process becomes more promising in real applications in the near future.

  6. Cotton (Gossypium hirsutum) 14-3-3 proteins participate in regulation of fibre initiation and elongation by modulating brassinosteroid signalling.

    Science.gov (United States)

    Zhou, Ying; Zhang, Ze-Ting; Li, Mo; Wei, Xin-Zheng; Li, Xiao-Jie; Li, Bing-Ying; Li, Xue-Bao

    2015-02-01

    Cotton (Gossypium hirsutum) fibre is an important natural raw material for textile industry in the world. Understanding the molecular mechanism of fibre development is important for the development of future cotton varieties with superior fibre quality. In this study, overexpression of Gh14-3-3L in cotton promoted fibre elongation, leading to an increase in mature fibre length. In contrast, suppression of expression of Gh14-3-3L, Gh14-3-3e and Gh14-3-3h in cotton slowed down fibre initiation and elongation. As a result, the mature fibres of the Gh14-3-3 RNAi transgenic plants were significantly shorter than those of wild type. This 'short fibre' phenotype of the 14-3-3 RNAi cotton could be partially rescued by application of 2,4-epibrassinolide (BL). Expression levels of the BR-related and fibre-related genes were altered in the Gh14-3-3 transgenic fibres. Furthermore, we identified Gh14-3-3 interacting proteins (including GhBZR1) in cotton. Site mutation assay revealed that Ser163 in GhBZR1 and Lys51/56/53 in Gh14-3-3L/e/h were required for Gh14-3-3-GhBZR1 interaction. Nuclear localization of GhBZR1 protein was induced by BR, and phosphorylation of GhBZR1 by GhBIN2 kinase was helpful for its binding to Gh14-3-3 proteins. Additionally, 14-3-3-regulated GhBZR1 protein may directly bind to GhXTH1 and GhEXP promoters to regulate gene expression for responding rapid fibre elongation. These results suggested that Gh14-3-3 proteins may be involved in regulating fibre initiation and elongation through their interacting with GhBZR1 to modulate BR signalling. Thus, our study provides the candidate intrinsic genes for improving fibre yield and quality by genetic manipulation. © 2014 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.

  7. Suppression of phase-induced intensity noise in fibre optic delay line signal processors using an optical phase modulation technique.

    Science.gov (United States)

    Chan, Erwin H W

    2010-10-11

    A technique that can suppress the dominant phase-induced intensity noise in fibre optic delay line signal processors is presented. It is based on phase modulation of the optical carrier to distribute the phase noise at the information band into a high frequency band which can be filtered out. This technique is suitable for suppressing the phase noise in various delay line structures and for integrating in the conventional fibre optic links. It can also suppress the coherent interference effect at the same time. A model for predicting the amount of phase noise reduction in various delay line structures using the optical phase modulation technique is presented for the first time and is experimentally verified. Experimental results demonstrate the technique can achieve a large phase noise reduction in various fibre optic delay line signal processors.

  8. Synthetic xylan-binding modules for mapping of pulp fibres and wood sections

    Directory of Open Access Journals (Sweden)

    Daniel Geoffrey

    2007-10-01

    Full Text Available Abstract Background The complex carbohydrate composition of natural and refined plant material is not known in detail but a matter that is of both basic and applied importance. Qualitative assessment of complex samples like plant and wood tissues requires the availability of a range of specific probes. Monoclonal antibodies and naturally existing carbohydrate binding modules (CBMs have been used in the past to assess the presence of certain carbohydrates in plant tissues. However, the number of natural CBMs is limited and development of carbohydrate-specific antibodies is not always straightforward. We envisage the use of sets of very similar proteins specific for defined targets, like those developed by molecular evolution of a single CBM scaffold, as a suitable strategy to assess carbohydrate composition. An advantage of using synthetic CBMs lies in the possibility to study fine details of carbohydrate composition within non-uniform substrates like plant cell walls as made possible through minor differences in CBM specificity of the variety of binders that can be developed by genetic engineering. Results A panel of synthetic xylan-binding CBMs, previously selected from a molecular library based on the scaffold of CBM4-2 from xylanase Xyn10A of Rhodothermus marinus, was used in this study. The wild type CBM4-2 and evolved modules both showed binding to wood sections. However, differences were observed in the staining patterns suggesting that these modules have different xylan-binding properties. Also the staining stability varied between the CBMs, the most stable staining being obtained with one (X-2 of the synthetic modules. Treatment of wood materials resulted in altered signal intensities, thereby also demonstrating the potential application of engineered CBMs as analytical tools for quality assessment of diverse plant material processes. Conclusion In this study we have demonstrated the usefulness of synthetic xylan-binding modules as

  9. Emerging Optical Fibre Technologies with Potential Defence Applications

    Science.gov (United States)

    Loh, Wei H.; Hewak, Dan; Petrovich, Marco N.; Hayes, John R.; Stewart, Will; Clarkson, Andy

    2012-09-01

    Recent years have seen the development of a range of promising optical fibre technologies emerge, enabled by advances in materials and fabrication techniques. We describe 3 emerging areas in optical fibre developments: nanomechanical optical fibres, microstructured hollow core silica fibres for high peak optical power and/or extended infrared transmission, and chalcogenide glasses and fibres for mid-IR applications.

  10. Studies for the LHCb SciFi tracker. Development of modules from scintillating fibres and tests of their radiation hardness

    Energy Technology Data Exchange (ETDEWEB)

    Ekelhof, Robert Jan

    2016-05-18

    The LHCb detector will see a major upgrade in the LHC long shutdown 2, which is planned for 2019/20. Among others, the tracking stations, currently realised as silicon strip and drift tube detectors, will be replaced by the Scintillating Fibre (SciFi) Tracker. The SciFi Tracker is based on scintillating fibres with a diameter of 250 μm, read out by multichannel silicon photomultipliers. The two major challenges related to the fibres are the radiation damage of the light guidance and the production of precise multi-layer fibre mats. This thesis presents radiation hardness studies performed with protons at the tandem accelerator at Forschungszentrum Garching and in situ in the LHCb cavern. The obtained results are combined with additional data of the LHCb SciFi group and two different wavelength dependent models of the radiation induced attenuation are determined. These are used to simulate the relative light yield, for both models it drops to 83% on average at the end of the nominal lifetime of the SciFi Tracker. A machine and techniques to produce multi-layer fibre mats were developed and optimised. Procedures for the production and alignment are described. These are implemented in the serial production of the SciFi modules which will start in the second quarter 2016.

  11. Fiber Attachment Module Experiment (FAME): Using a Multiplexed Miniature Hollow Fiber Membrane Bioreactor Solution for Rapid Process Testing

    Science.gov (United States)

    Lunn, Griffin; Wheeler, Raymond; Hummerick, Mary; Birmele, Michele; Richards, Jeffrey; Coutts, Janelle; Koss, Lawrence; Spencer, Lashelle.; Johnsey, Marissa; Ellis, Ronald

    Bioreactor research, even today, is mostly limited to continuous stirred-tank reactors (CSTRs). These are not an option for microgravity applications due to the lack of a gravity gradient to drive aeration as described by the Archimedes principle. This has led to testing of Hollow Fiber Membrane Bioreactors (HFMBs) for microgravity applications, including possible use for wastewater treatment systems for the International Space Station (ISS). Bioreactors and filtration systems for treating wastewater could avoid the need for harsh pretreatment chemicals and improve overall water recovery. However, the construction of these reactors is difficult and commercial off-the-shelf (COTS) versions do not exist in small sizes. We have used 1-L modular HFMBs in the past, but the need to perform rapid testing has led us to consider even smaller systems. To address this, we designed and built 125-mL, rectangular reactors, which we have called the Fiber Attachment Module Experiment (FAME) system. A polycarbonate rack of four square modules was developed with each module containing removable hollow fibers. Each FAME reactor is self-contained and can be easily plumbed with peristaltic and syringe pumps for continuous recycling of fluids and feeding, as well as fitted with sensors for monitoring pH, dissolved oxygen, and gas measurements similar to their larger counterparts. The first application tested in the FAME racks allowed analysis of over a dozen fiber surface treatments and three inoculation sources to achieve rapid reactor startup and biofilm attachment (based on carbon oxidation and nitrification of wastewater). With these miniature FAME reactors, data for this multi-factorial test were collected in duplicate over a six-month period; this greatly compressed time period required for gathering data needed to study and improve bioreactor performance.

  12. Fibre illumination system

    DEFF Research Database (Denmark)

    2012-01-01

    Source: EP2426402A The invention relates to a fibre illumination module and system for the collection and delivery of daylight for illumination purposes. The fibre illumination module comprises a plurality of collector elements, each collector element comprising an input fibre having a first end......-directional arrangement. The fibre illumination system comprises a fibre illumination module of the above-mentioned type. By the invention, daylight may be exploited for the illumination of remote interior spaces of buildings in order to save energy, and improve the well-being of users in both housing and working...

  13. Pulsed ytterbium-doped fibre laser with a combined modulator based on single-wall carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Khudyakov, D V; Borodkin, A A; Vartapetov, S K [Physics Instrumentation Center, A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, Troitsk, Moscow Region (Russian Federation); Lobach, A S [Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region (Russian Federation)

    2015-09-30

    This paper describes an all-normal-dispersion pulsed ytterbium-doped fibre ring laser mode-locked by a nonlinear combined modulator based on single-wall carbon nanotubes. We have demonstrated 1.7-ps pulse generation at 1.04 μm with a repetition rate of 35.6 MHz. At the laser output, the pulses were compressed to 180 fs. We have examined an intracavity nonlinear modulator which utilises nonlinear polarisation ellipse rotation in conjunction with a saturable absorber in the form of a polymer-matrix composite film containing single-wall carbon nanotubes. (lasers)

  14. Assessment of specific migration to aqueous simulants of a new active food packaging containing essential oils by means of an automatic multiple dynamic hollow fibre liquid phase microextraction system.

    Science.gov (United States)

    Salafranca, Jesús; Pezo, Davinson; Nerín, Cristina

    2009-05-01

    The determination of specific migration in the three aqueous food simulants (water, 3% acetic acid and 10% ethanol) from experimental active packaging polypropylene-based films containing natural essential oils as active agents has been carried out for the first time by a two-phase hollow fibre liquid phase microextraction (HFLPME). Due to the high number of variables involved, an experimental design has been applied. High throughput, with six samples running simultaneously in a highly automated system working in dynamic extraction mode, has been achieved. The main analytical characteristics are detection limits as low as 0.01 microg kg(-1), linearity higher than 0.99 for almost 5 magnitude orders, average precision below 16% as RSD and concentration factors ranging from 4 to 189. Migration of 43 compounds including terpenes, alkanes, plastic additives and degradation compounds is reported. According to the results obtained and European legislation, the packaging prototypes tested could be safely marketed.

  15. Experimental 2.5 Gbit/s QPSK WDM coherent phase modulated radio-over-fibre link with digital demodulation by a K-means algorithm

    DEFF Research Database (Denmark)

    Guerrero Gonzalez, Neil; Caballero Jambrina, Antonio; Amaya Fernández, Ferney Orlando

    2009-01-01

    Highest reported bit rate of 2.5 Gbit/s for optically phase modulated radio-over-fibre link employing coherent detection is demonstrated. Demodulation of 3·2.5 Gbit/s QPSK modulated WDM channels, is achieved after 79km of transmission through deployed fiber.......Highest reported bit rate of 2.5 Gbit/s for optically phase modulated radio-over-fibre link employing coherent detection is demonstrated. Demodulation of 3·2.5 Gbit/s QPSK modulated WDM channels, is achieved after 79km of transmission through deployed fiber....

  16. FOST 2 Upgrade with Hollow-Fiber CTA FO Module and Generation of Osmotic Agent for Microorganism Growth Studies

    Science.gov (United States)

    Parodi, Jurek; Mangado, Jaione Romero; Stefanson, Ofir; Flynn, Michael; Shaw, Hali; Beeler, David

    2016-01-01

    FOST 2 is an integrated membrane system that incorporates a forward osmosis subsystem and a reverse osmosis subsystem working in series. It has been designed as a post treatment system to process the effluent from the Membrane Aerated Biological Reactor developed at NASA Johnson Space Center and Texas Tech University. Its function is to remove dissolved solids residual such as ammonia and suspended solids, as well as to provide a physical barrier to microbial and viral contamination. A tubular CTA membrane module from HTI and a flat-sheet lipid-base membrane module from Porifera were integrated and tested on FOST 2 in the past, using both a bioreactor's effluent and greywater as the feed solution. This paper documents the performance of FOST 2 after its upgrade with a hollow-fiber CTA membrane module from Toyobo, treating real black-water to generate the osmotic agent solution necessary to conduct growth studies of genetically engineered microorganism for the Synthetic Biological Membrane project.

  17. Microstructured Optical Fibres

    DEFF Research Database (Denmark)

    1999-01-01

    complete PBGs, which reflects light incident from air or vacuum. Such structures may be used as cladding structures in optical fibres, where light is confined and thereby guided in a hollow core region. In addition, the present invention relates to designs for ultra low-loss PBG waveguiding structures...

  18. Design and verification of a novel hollow vibrating module for laser machining.

    Science.gov (United States)

    Wang, Zhaozhao; Jang, Seungbong; Kim, EunHee; Jeon, Yongho; Lee, Soo-Hun; Lee, Moon G

    2015-04-01

    If a vibration module is added on laser machining system, the quality of surface finish and aspect ratio on metals can be significantly enhanced. In this study, a single mobility model of vibrating laser along the path of laser beam was put forward. In order to realize the desired unidirectional motion, a resonance type vibration module with optical lens was designed and manufactured. This cylindrical module was composed of curved-beam flexure elements. The cylindrical coordinate system was established to describe the relationship of a curved-beam flexure element's motion and deformation. In addition, the stiffness matrix of the curved-beam element was obtained. Finite element method and dynamical modeling were provided to analyze the resonance frequency and the displacement of the motion. The feasibility of the design was demonstrated with the help of experiments on frequency response. Experimental results show good agreement with theoretical analysis and simulation predictions.

  19. Microglia-derived purines modulate mossy fibre synaptic transmission and plasticity through P2X4 and A1 receptors.

    Science.gov (United States)

    George, Jimmy; Cunha, Rodrigo A; Mulle, Christophe; Amédée, Thierry

    2016-05-01

    Recent data have provided evidence that microglia, the brain-resident macrophage-like cells, modulate neuronal activity in both physiological and pathophysiological conditions, and microglia are therefore now recognized as synaptic partners. Among different neuromodulators, purines, which are produced and released by microglia, have emerged as promising candidates to mediate interactions between microglia and synapses. The cellular effects of purines are mediated through a large family of receptors for adenosine and for ATP (P2 receptors). These receptors are present at brain synapses, but it is unknown whether they can respond to microglia-derived purines to modulate synaptic transmission and plasticity. Here, we used a simple model of adding immune-challenged microglia to mouse hippocampal slices to investigate their impact on synaptic transmission and plasticity at hippocampal mossy fibre (MF) synapses onto CA3 pyramidal neurons. MF-CA3 synapses show prominent forms of presynaptic plasticity that are involved in the encoding and retrieval of memory. We demonstrate that microglia-derived ATP differentially modulates synaptic transmission and short-term plasticity at MF-CA3 synapses by acting, respectively, on presynaptic P2X4 receptors and on adenosine A1 receptors after conversion of extracellular ATP to adenosine. We also report that P2X4 receptors are densely located in the mossy fibre tract in the dentate gyrus-CA3 circuitry. In conclusion, this study reveals an interplay between microglia-derived purines and MF-CA3 synapses, and highlights microglia as potent modulators of presynaptic plasticity. © 2016 The Authors. European Journal of Neuroscience published by Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  20. Multimaterial piezoelectric fibres

    Science.gov (United States)

    Egusa, S.; Wang, Z.; Chocat, N.; Ruff, Z. M.; Stolyarov, A. M.; Shemuly, D.; Sorin, F.; Rakich, P. T.; Joannopoulos, J. D.; Fink, Y.

    2010-08-01

    Fibre materials span a broad range of applications ranging from simple textile yarns to complex modern fibre-optic communication systems. Throughout their history, a key premise has remained essentially unchanged: fibres are static devices, incapable of controllably changing their properties over a wide range of frequencies. A number of approaches to realizing time-dependent variations in fibres have emerged, including refractive index modulation, nonlinear optical mechanisms in silica glass fibres and electroactively modulated polymer fibres. These approaches have been limited primarily because of the inert nature of traditional glassy fibre materials. Here we report the composition of a phase internal to a composite fibre structure that is simultaneously crystalline and non-centrosymmetric. A ferroelectric polymer layer of 30μm thickness is spatially confined and electrically contacted by internal viscous electrodes and encapsulated in an insulating polymer cladding hundreds of micrometres in diameter. The structure is thermally drawn in its entirety from a macroscopic preform, yielding tens of metres of piezoelectric fibre. The fibres show a piezoelectric response and acoustic transduction from kilohertz to megahertz frequencies. A single-fibre electrically driven device containing a high-quality-factor Fabry-Perot optical resonator and a piezoelectric transducer is fabricated and measured.

  1. Fibre illumination system

    DEFF Research Database (Denmark)

    2012-01-01

    -directional arrangement. The fibre illumination system comprises a fibre illumination module of the above-mentioned type. By the invention, daylight may be exploited for the illumination of remote interior spaces of buildings in order to save energy, and improve the well-being of users in both housing and working...

  2. Digital coherent receiver for phase modulated radio-over-fibre optical links

    DEFF Research Database (Denmark)

    Zibar, Darko; Yu, Xianbin; Peucheret, Christophe

    2009-01-01

    A novel digital signal processing-based coherent receiver for phase-modulated radio-over-fiber (RoF) optical links is presented and demonstrated experimentally. Error-free demodulation of 50-Mbaud binary phase-shift keying (BPSK) and quadrature phase-shift keying data signal modulated on a 5-GHz...... radio-frequency (RF) carrier is experimentally demonstrated using the proposed digital coherent receiver. Additionally, a wavelength-division-multiplexing (WDM) phase-modulated RoF optical link is experimentally demonstrated. A 3 x50 Mb/s WDM transmission of a BPSK modulated 5-GHz RF carrier is achieved...

  3. Gas-liquid mass transfer in a cross-flow hollow fiber module : Analytical model and experimental validation

    NARCIS (Netherlands)

    Dindore, V. Y.; Versteeg, G. F.

    2005-01-01

    The cross-flow operation of hollow fiber membrane contactors offers many advantages and is preferred over the parallel-flow contactors for gas-liquid mass transfer operations. However, the analysis of such a cross-flow membrane gas-liquid contactor is complicated due to the change in concentrations

  4. Hollow Core?

    Science.gov (United States)

    Qiao, G. J.; Liu, J. F.; Wang, Yang; Wu, X. J.; Han, J. L.

    We carried out the Gaussian fitting to the profile of PSR B1237+25 and found that six components rather than five are necessary to make a good fit. In the central part, we found that the core emission is not filled pencil beam but is a small hollow cone. This implies that the impact angle could be $\\beta<0.5^\\circ$. The ``hollow core'' is in agreement with Inverse Compton Scattering model of radio pulsars.

  5. Automated segmentation of wood fibres in micro-CT images of paper.

    Science.gov (United States)

    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. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

  6. Extraction of lotus fibres from lotus stems under microwave irradiation.

    Science.gov (United States)

    Cheng, Cheng; Guo, Ronghui; Lan, Jianwu; Jiang, Shouxiang

    2017-09-01

    An efficient technology for preparing lotus fibres under microwave irradiation was developed. The lotus fibres were characterized by scanning electron microscopy, Fourier transform infrared spectrometry, X-ray diffraction and thermogravimetry. Lotus fibres prepared are a kind of hollow fibres which are composed of a superfine fibre and an external shell. The effect of the treatment time with hydrogen peroxide under microwave irradiation on components, whiteness, moisture regain, removal rate of impurities, fineness, tensile strength and breaking elongation of lotus fibres was investigated. The results show that the cellulose content in lotus fibres increases with increase in treatment time. Whiteness and moisture regain of lotus fibres increase with increase in treatment time with hydrogen peroxide. The removal rate of impurities and the fineness of lotus fibres are improved after they are treated with hydrogen peroxide. Microwave irradiation is supposed to be an efficient method for producing lotus fibres.

  7. hollow fibre supported liquid membrane extraction of ...

    African Journals Online (AJOL)

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    Belkhouche, N-E.; Didi, M.A.; Romero, R.; Jönsson, J.Å.; Villemin, D. J. Membr. Sci. 2006, 284, 398. 36. Yang, Y.; Miller, D.J.; Hawthorne, S.B. J. Chem. Eng. Data 1997, 42, 908. 37. Zhang, W.; Huang; X.; Li, Y.; Qu, Y.; Gao, P. Appl. Microbiol. Biotech. 2006, 70, 315. 38. Jönsson, J.Å.; Mathiasson, L. LC-GC Europe 2003, 16, ...

  8. PERFORMANCE OF THIN FILM PV MINI-MODULES IN A SUPERSTRATE CONFIGURATION (CdTe) ON GLASS WITH NOVEL FIBRE LASER PROCESSING

    OpenAIRE

    BARDIZZA GIORGIO; BOSIO Alessio; SOZZI Michele; MUELLEJANS Harald; DUNLOP Ewan

    2013-01-01

    A new pulsed laser technique based on Photonic Crystal Fibres (PCF) has been developed and tested within the European funded Alpine project for the improvement, in terms of precision and speed, of the existing scribing technology in PV modules through the usage of high quality beam fiber lasers. In this work we report about the first evaluation of the quality of the scribing process performed by innovative PCF lasers according to the particular patterning steps (P1, P2 and P3) which are ap...

  9. Studies for the LHCb SciFi Tracker - Development of Modules from Scintillating Fibres and Tests of their Radiation Hardness

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00341158

    The LHCb detector will see a major upgrade in the LHC long shutdown 2, which is planned for 2019/20. Among others, the tracking stations, currently realised as silicon strip and drift tube detectors, will be replaced by the Scintillating Fibre (SciFi) Tracker. The SciFi Tracker is based on scintillating fibres with a diameter of $\\text 250 \\mu m$, read out by multichannel silicon photomultipliers. The two major challenges related to the fibres are the radiation damage of the light guidance and the production of precise multi-layer fibre mats. This thesis presents radiation hardness studies performed with protons at the tandem accelerator at Forschungszentrum Garching and in situ in the LHCb cavern. The obtained results are combined with additional data of the LHCb SciFi group and two different wavelength dependent models of the radiation induced attenuation are determined. These are used to simulate the relative light yield, for both models it drops to $83 \\%$ on average at the end of the nominal lifetime of ...

  10. Caffeine Modulates Vesicle Release and Recovery at Cerebellar Parallel Fibre Terminals, Independently of Calcium and Cyclic AMP Signalling.

    Science.gov (United States)

    Dobson, Katharine L; Jackson, Claire; Balakrishnan, Saju; Bellamy, Tomas C

    2015-01-01

    Cerebellar parallel fibres release glutamate at both the synaptic active zone and at extrasynaptic sites-a process known as ectopic release. These sites exhibit different short-term and long-term plasticity, the basis of which is incompletely understood but depends on the efficiency of vesicle release and recycling. To investigate whether release of calcium from internal stores contributes to these differences in plasticity, we tested the effects of the ryanodine receptor agonist caffeine on both synaptic and ectopic transmission. Whole cell patch clamp recordings from Purkinje neurons and Bergmann glia were carried out in transverse cerebellar slices from juvenile (P16-20) Wistar rats. Caffeine caused complex changes in transmission at both synaptic and ectopic sites. The amplitude of postsynaptic currents in Purkinje neurons and extrasynaptic currents in Bergmann glia were increased 2-fold and 4-fold respectively, but paired pulse ratio was substantially reduced, reversing the short-term facilitation observed under control conditions. Caffeine treatment also caused synaptic sites to depress during 1 Hz stimulation, consistent with inhibition of the usual mechanisms for replenishing vesicles at the active zone. Unexpectedly, pharmacological intervention at known targets for caffeine--intracellular calcium release, and cAMP signalling--had no impact on these effects. We conclude that caffeine increases release probability and inhibits vesicle recovery at parallel fibre synapses, independently of known pharmacological targets. This complex effect would lead to potentiation of transmission at fibres firing at low frequencies, but depression of transmission at high frequency connections.

  11. Optical fibres

    CERN Multimedia

    1992-01-01

    These optical fibres are used to detect particles passing through in bunches. Made from scintillating material, the fibres glow when a high energy particle passes through them. These detectors are known as spaghetti detectors and are used to measure the energy of particles.

  12. The Electrospun Ceramic Hollow Nanofibers

    Directory of Open Access Journals (Sweden)

    Shahin Homaeigohar

    2017-11-01

    Full Text Available Hollow nanofibers are largely gaining interest from the scientific community for diverse applications in the fields of sensing, energy, health, and environment. The main reasons are: their extensive surface area that increases the possibilities of engineering, their larger accessible active area, their porosity, and their sensitivity. In particular, semiconductor ceramic hollow nanofibers show greater space charge modulation depth, higher electronic transport properties, and shorter ion or electron diffusion length (e.g., for an enhanced charging–discharging rate. In this review, we discuss and introduce the latest developments of ceramic hollow nanofiber materials in terms of synthesis approaches. Particularly, electrospinning derivatives will be highlighted. The electrospun ceramic hollow nanofibers will be reviewed with respect to their most widely studied components, i.e., metal oxides. These nanostructures have been mainly suggested for energy and environmental remediation. Despite the various advantages of such one dimensional (1D nanostructures, their fabrication strategies need to be improved to increase their practical use. The domain of nanofabrication is still advancing, and its predictable shortcomings and bottlenecks must be identified and addressed. Inconsistency of the hollow nanostructure with regard to their composition and dimensions could be one of such challenges. Moreover, their poor scalability hinders their wide applicability for commercialization and industrial use.

  13. Hollow MEMS

    DEFF Research Database (Denmark)

    Larsen, Peter Emil

    a hollow MEMS sensor has been designed, fabricated and tested. Combined density, viscosity, buoyant mass spectrometry and IR absorption spectroscopy are possible on liquid samples and micron sized suspended particles (e.g. single cells). Measurements are based on changes in the resonant behavior...... of these sensors. Optimization of the microfabrication process has led to a process yield of almost 100% .This is achieved despite the fact, that the process still offers a high degree of flexibility. By simple modifications the Sensor shape can be optimized for different size ranges and sensitivities...... technologies and pre-concentration approaches. A thorough theoretical analysis of the expected sensor responsivity and sensitivity is performed. Predictions made are confirmed by finite element simulations. Using these tools the sensor geometry is optimized for ideal performance in both mass density and IR...

  14. Caffeine Modulates Vesicle Release and Recovery at Cerebellar Parallel Fibre Terminals, Independently of Calcium and Cyclic AMP Signalling

    Science.gov (United States)

    Dobson, Katharine L.; Jackson, Claire; Balakrishnan, Saju; Bellamy, Tomas C.

    2015-01-01

    Background Cerebellar parallel fibres release glutamate at both the synaptic active zone and at extrasynaptic sites—a process known as ectopic release. These sites exhibit different short-term and long-term plasticity, the basis of which is incompletely understood but depends on the efficiency of vesicle release and recycling. To investigate whether release of calcium from internal stores contributes to these differences in plasticity, we tested the effects of the ryanodine receptor agonist caffeine on both synaptic and ectopic transmission. Methods Whole cell patch clamp recordings from Purkinje neurons and Bergmann glia were carried out in transverse cerebellar slices from juvenile (P16-20) Wistar rats. Key Results Caffeine caused complex changes in transmission at both synaptic and ectopic sites. The amplitude of postsynaptic currents in Purkinje neurons and extrasynaptic currents in Bergmann glia were increased 2-fold and 4-fold respectively, but paired pulse ratio was substantially reduced, reversing the short-term facilitation observed under control conditions. Caffeine treatment also caused synaptic sites to depress during 1 Hz stimulation, consistent with inhibition of the usual mechanisms for replenishing vesicles at the active zone. Unexpectedly, pharmacological intervention at known targets for caffeine—intracellular calcium release, and cAMP signalling—had no impact on these effects. Conclusions We conclude that caffeine increases release probability and inhibits vesicle recovery at parallel fibre synapses, independently of known pharmacological targets. This complex effect would lead to potentiation of transmission at fibres firing at low frequencies, but depression of transmission at high frequency connections. PMID:25933382

  15. Caffeine Modulates Vesicle Release and Recovery at Cerebellar Parallel Fibre Terminals, Independently of Calcium and Cyclic AMP Signalling.

    Directory of Open Access Journals (Sweden)

    Katharine L Dobson

    Full Text Available Cerebellar parallel fibres release glutamate at both the synaptic active zone and at extrasynaptic sites-a process known as ectopic release. These sites exhibit different short-term and long-term plasticity, the basis of which is incompletely understood but depends on the efficiency of vesicle release and recycling. To investigate whether release of calcium from internal stores contributes to these differences in plasticity, we tested the effects of the ryanodine receptor agonist caffeine on both synaptic and ectopic transmission.Whole cell patch clamp recordings from Purkinje neurons and Bergmann glia were carried out in transverse cerebellar slices from juvenile (P16-20 Wistar rats.Caffeine caused complex changes in transmission at both synaptic and ectopic sites. The amplitude of postsynaptic currents in Purkinje neurons and extrasynaptic currents in Bergmann glia were increased 2-fold and 4-fold respectively, but paired pulse ratio was substantially reduced, reversing the short-term facilitation observed under control conditions. Caffeine treatment also caused synaptic sites to depress during 1 Hz stimulation, consistent with inhibition of the usual mechanisms for replenishing vesicles at the active zone. Unexpectedly, pharmacological intervention at known targets for caffeine--intracellular calcium release, and cAMP signalling--had no impact on these effects.We conclude that caffeine increases release probability and inhibits vesicle recovery at parallel fibre synapses, independently of known pharmacological targets. This complex effect would lead to potentiation of transmission at fibres firing at low frequencies, but depression of transmission at high frequency connections.

  16. Modulation of the faecal microbiome of healthy adult dogs by inclusion of potato fibre in the diet.

    Science.gov (United States)

    Panasevich, Matthew R; Kerr, Katherine R; Dilger, Ryan N; Fahey, George C; Guérin-Deremaux, Laetitia; Lynch, Gary L; Wils, Daniel; Suchodolski, Jan S; Steer, Jörg M; Dowd, Scot E; Swanson, Kelly S

    2015-01-14

    Inclusion of fermentable fibres in the diet can have an impact on the hindgut microbiome and provide numerous health benefits to the host. Potato fibre (PF), a co-product of potato starch isolation, has a favourable chemical composition of pectins, resistant and digestible starch, cellulose, and hemicelluloses. The objective of the present study was to evaluate the effect of increasing dietary PF concentrations on the faecal microbiome of healthy adult dogs. Fresh faecal samples were collected from ten female dogs with hound bloodlines (6·13 (SEM 0·17) years; 22·0 (SEM 2·1) kg) fed five test diets containing graded concentrations of PF (0, 1·5, 3, 4·5 or 6% as-fed; Roquette Frères) in a replicated 5 × 5 Latin square design. Extraction of DNA was followed by amplification of the V4-V6 variable region of the 16S rRNA gene using barcoded primers. Sequences were classified into taxonomic levels using Basic Local Alignment Search Tool (BLASTn) against a curated GreenGenes database. Inclusion of PF increased (P< 0·05) the faecal proportions of Firmicutes, while those of Fusobacteria decreased (P< 0·05). Similar shifts were observed at the genus level and were confirmed by quantitative PCR (qPCR) analysis. With increasing concentrations of PF, faecal proportions of Faecalibacterium increased (P< 0·05). Post hoc Pearson's correlation analysis showed positive (P< 0·05) correlations with Bifidobacterium spp. and butyrate production and Lactobacillus spp. concentrations. Overall, increases in the proportion of Faecalibacterium (not Lactobacillus/Bifidobacterium, as confirmed by qPCR analysis) and faecal SCFA concentrations with increasing dietary PF concentrations suggest that PF is a possible prebiotic fibre.

  17. Non-Linear Fibres for Widely Tunable Femtosecond Fibre Lasers

    DEFF Research Database (Denmark)

    Pedersen, Martin Erland Vestergaard

    This Ph.D. thesis investigates how intramodal and intermodal nonlinear processes in few-moded fibres can be used to generate light sources at wavelengths outside the spectral gain-bands of rare-earth-doped opticalfibres. The design of two specialty few-moded fibres for use in a widely tunable...... femtosecond fibre laser is presented. The two fibres are used to facilitate the shifting of a soliton in a cascade configuration from the ytterbium gain-band and to a wavelength of 1280 nm. The temporal pulse duration is on a femtosecond scale with a pulse energy of 5 nJ. The experimentally observed soliton......, as opposed to the commonly used version, is able to reproduce the intermodal four-wave mixing experiment. The relation between the intramodal self-phase modulation and the intramodal Raman effect is determined from experimental measurements on a number of step-index fibres. The Raman fraction is found...

  18. Fibre typing of intrafusal fibres

    Science.gov (United States)

    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

  19. Switching a Nanocluster Core from Hollow to Non-hollow

    KAUST Repository

    Bootharaju, Megalamane Siddaramappa

    2016-03-24

    Modulating the structure-property relationship in atomically precise nanoclusters (NCs) is vital for developing novel NC materials and advancing their applications. While promising biphasic ligand-exchange (LE) strategies have been developed primarily to attain novel NCs, understanding the mechanistic aspects involved in tuning the core and the ligand-shell of NCs in such biphasic processes is challenging. Here, we design a single phase LE process that enabled us to elucidate the mechanism of how a hollow NC (e.g., [Ag44(SR)30]4-, -SR: thiolate) converts into a non-hollow NC (e.g., [Ag25(SR)18]-), and vice versa. Our study reveals that the complete LE of the hollow [Ag44(SPhF)30]4- NCs (–SPhF: 4-fluorobenzenethiolate) with incoming 2,4-dimethylbenzenethiol (HSPhMe2) induced distortions in the Ag44 structure forming the non-hollow [Ag25(SPhMe2)18]- by a disproportionation mechanism. While the reverse reaction of [Ag25(SPhMe2)18]- with HSPhF prompted an unusual dimerization of Ag25, followed by a rearrangement step that reproduces the original [Ag44(SPhF)30]4-. Remarkably, both the forward and the backward reactions proceed through similar size intermediates that seem to be governed by the boundary conditions set by the thermodynamic and electronic stability of the hollow and non-hollow metal cores. Furthermore, the resizing of NCs highlights the surprisingly long-range effect of the ligands which are felt by atoms far deep in the metal core, thus opening a new path for controlling the structural evolution of nanoparticles.

  20. Fibre optic gyroscope with single-mode fibre and loop-back phase shift compensation

    Science.gov (United States)

    Skalský, Michal; Havránek, Zdeněk.; Fialka, Jiří

    2017-12-01

    An all-fibre optical sensor of an angular velocity (fibre-optic gyroscope) based on the Sagnac interferometer and using a loop-back phase shift compensation is presented. The sensing loop consists of 760 metres of an ordinary single-mode fibre, which makes this setup cost-effective. To ensure principles of beams reciprocity, randomly induced changes of polarization in the fibre are reduced by using an unpolarized light. This is achieved by a fibre Lyot depolarizer and a super fluorescent fibre source consisting of an erbium-doped fibre pumped by a laser diode. Unlike common approaches to the unpolarized fibre-optic gyroscope with a single-mode fibre, whose output is naturally nonlinear, we use a loop-back compensation of a rotation-induced phase shift to achieve a linear response. In most cases, this technique requires fast electro-optical modulator, which is compatible only with an expensive polarization-maintaining fibre. We use a novel loop-back modulation scheme utilizing only harmonic signals and thus compatible with a piezoelectric fibre stretcher, which can be used with any kind of optical fibre. As result of the closed-loop operation, the range of the gyroscope's linearity is greatly increased and a sensitivity to source power changes is suppressed. We describe the gyroscope setup with proposed modulation method and provide a comparison to the common open-loop setup.

  1. Dietary Fibre

    NARCIS (Netherlands)

    Kamp, van der J.W.; Asp, N.G.; Miller Jones, J.; Schaafsma, G.

    2004-01-01

    In this book invited expert scientists of leading research groups all over the world will address the following issues: Definitions, health claims and new challenges, Analytical tools, technological aspects and applications, Health Benefits of dietary fibre, including both authoritative generic

  2. Cocoa and cocoa fibre differentially modulate IgA and IgM production at mucosal sites.

    Science.gov (United States)

    Massot-Cladera, Malen; Franch, Àngels; Pérez-Cano, Francisco J; Castell, Margarida

    2016-05-01

    Previous studies have shown that a 10 % cocoa (C10) diet, containing polyphenols and fibre among others, modifies intestinal and systemic Ig production. The present study aimed at evaluating the impact of C10 on IgA and IgM production in the intestinal and extra-intestinal mucosal compartments, establishing the involvement of cocoa fibre (CF) in such effects. Mechanisms by which C10 intake may affect IgA synthesis in the salivary glands were also studied. To this effect, rats were fed either a standard diet, a diet containing C10, CF or inulin. Intestinal (the gut wash (GW), Peyer's patches (PP) and mesenteric lymph nodes (MLN)) and extra-intestinal (salivary glands) mucosal tissues and blood samples were collected for IgA and IgM quantification. The gene expressions of IgA production- and homing-related molecules were studied in the salivary glands. The C10 diet decreased intestinal IgA and IgM production. Although the CF diet decreased the GW IgA concentration, it increased PP, MLN and serum IgA concentrations. Both the C10 and the CF diets produced a down-regulatory effect on IgA secretion in the extra-intestinal tissues. The C10 diet interacted with the mechanisms involved in IgA synthesis, whereas the CF showed particular effects on the homing and transcytosis of IgA across the salivary glands. Overall, CF was able to up-regulate IgA production in the intestinal-inductor compartments, whereas it down-regulated its production at the mucosal-effector ones. Further studies must be directed to ascertain the mechanisms involved in the effect of particular cocoa components on gut-associated lymphoid tissue.

  3. Experiments on fibre orientation in UHPC

    Science.gov (United States)

    Vítek, Jan L.; Čítek, David; Coufal, Robert

    2017-09-01

    Distribution and orientation of fibres in fibre reinforced composites are essential for the structural performance of elements and structures. The paper deals with experimental research where this phenomenon was investigated. During construction of the first large footbridge, many experiments were made, which should guarantee the quality of the UHPC segments. Later the problem was investigated more in detail, when a technology of hollow core slabs was developed. Three basic experiments were carried out where the direction of pouring of concrete and the structural response were compared. Standard beams which were cast in horizontal and vertical positions, small beams were cut from the hollow core slab in different directions and finally thin slabs were cast in horizontal and vertical directions and their load carrying capacity was tested. Reduction of flexural strength in different directions may vary significantly.

  4. Design of fibre reinforced PV concepts for building integrated applications

    NARCIS (Netherlands)

    Reinders, Angelina H.M.E.; de Wit, H.; de Boer, Andries; Ossenbrink Sinke, W.; Helm, P.

    2009-01-01

    Fibre reinforced polymers present an interesting encapsulation medium for PV-modules. Glass fibres can provide increased strength and stiffness to thin polymer layers overcoming the brittleness and limited deformability of glass-panes. Glass fibre reinforced polymers allows for transparency over a

  5. Method of optical coherence tomography with parallel depth-resolved signal reception and fibre-optic phase modulators

    Energy Technology Data Exchange (ETDEWEB)

    Morozov, A N; Turchin, I V [Institute of Applied Physics, Russian Academy of Sciences, Nizhnii Novgorod (Russian Federation)

    2013-12-31

    The method of optical coherence tomography with the scheme of parallel reception of the interference signal (P-OCT) is developed on the basis of spatial paralleling of the reference wave by means of a phase diffraction grating producing the appropriate time delay in the Mach–Zehnder interferometer. The absence of mechanical variation of the optical path difference in the interferometer essentially reduces the time required for 2D imaging of the object internal structure, as compared to the classical OCT that uses the time-domain method of the image construction, the sensitivity and the dynamic range being comparable in both approaches. For the resulting field of the interfering object and reference waves an analytical expression is derived that allows the calculation of the autocorrelation function in the plane of photodetectors. For the first time a method of linear phase modulation by 2π is proposed for P-OCT systems, which allows the use of compact high-frequency (a few hundred kHz) piezoelectric cell-based modulators. For the demonstration of the P-OCT method an experimental setup was created, using which the images of the inner structure of biological objects at the depth up to 1 mm with the axial spatial resolution of 12 μm were obtained. (optical coherence tomography)

  6. Electrospun manganese-cobalt oxide hollow nanofibres synthesized via combustion reactions and their lithium storage performance

    Science.gov (United States)

    Hwang, Soo Min; Kim, So Yeun; Kim, Jae-Geun; Kim, Ki Jae; Lee, Jong-Won; Park, Min-Sik; Kim, Young-Jun; Shahabuddin, Mohammed; Yamauchi, Yusuke; Kim, Jung Ho

    2015-04-01

    Mesoporous hollow fibres of MnCo2O4 and CoMn2O4 were synthesized by electrospinning and highly exothermic oxygen-mediated combustion reactions during calcination, in which the heating rate affected the final fibre morphology (e.g., single- or double-shell). The anodes consisting of hollow fibres showed excellent electrochemical properties for lithium-ion batteries.Mesoporous hollow fibres of MnCo2O4 and CoMn2O4 were synthesized by electrospinning and highly exothermic oxygen-mediated combustion reactions during calcination, in which the heating rate affected the final fibre morphology (e.g., single- or double-shell). The anodes consisting of hollow fibres showed excellent electrochemical properties for lithium-ion batteries. Electronic supplementary information (ESI) available: Experimental section; additional thermal analyses; XRD patterns; SEM and TEM results; N2 adsorption isotherms; differential capacity plots of galvanostatic voltage profiles and coulombic efficiency during cycling. See DOI: 10.1039/c5nr01145k

  7. Hollow Prosthetic Eyes.

    Science.gov (United States)

    Worrell, Emma

    A new technique to produce hollow prostheses is presented. A small case series of patients utilized standard methods to fabricate hollow ocular prostheses where rehabilitation had proved difficult. This article describes the fabrication and results of hollow ocular prostheses. Each hollow eye was significantly reduced in weight, one-third lighter than the original weight, with the exact size, shape, and volume of the existing solid prosthesis. This simple design significantly reduced the weight of these eyes and revolutionized these patients' rehabilitation. Previously the solid prostheses overburdened the lower eyelids, causing discomfort, irritation, discharge, and reddening, whereas the new lightweight prostheses are unobtrusive, comfortable, and good aesthetically.

  8. Photonic Crystal Fibres for Dispersion and Sensor Applications

    DEFF Research Database (Denmark)

    Sørensen, Thorkild

    2005-01-01

    of the involved nonlinear processes. A hollow-core photonic crystal fibre (HC-PCF) is used as a sensor for gas. It is filled with two gasses, 12C2H2 acetylene, and H13CN hydrogen cyanide, and the transmission spectra are subject for a discussion. A model for infusion speed of fluids to a capillary presented...

  9. [Hollow foot in adults].

    Science.gov (United States)

    Braun, S

    1997-01-01

    Contrary to the general impression, the hollow foot is much more common than the flat foot. We distinguish three categories of hollow foot: varus hollow (clinical form I), valgus hollow (clinical form II), and pseudo-hollow (clinical form III). These three clinical forms have a common deviation dynamics, the consequence of shortening of the sural-Achilles-calcaneoplantar system. Metatarsalgia often precedes deformation of the front of the foot. Talalgia is linked to excess traction or to a conflict between the heel and the back of the shoe. Common therapy consists of plantar orthoses, eventually toe orthoses and orthopedic shoes. When surgery is used in the adult, it is generally not to correct excess cavus but to correct problems of the front of the foot such as hallux valgus, involvement of the second metatarsal bone (??), or toenails.

  10. Fibre Optic Communication Key Devices

    CERN Document Server

    Grote, Norbert

    2012-01-01

    The book gives an in-depth description of the key devices of current and next generation fibre optic communication networks. In particular, the book covers devices such as semiconductor lasers, optical amplifiers, modulators, wavelength filters, and detectors but the relevant properties of optical fibres as well. The presentations include the physical principles underlying the various devices, the technologies used for the realization of the different devices, typical performance characteristics and limitations, and development trends towards more advanced components are also illustrated. Thus the scope of the book spans relevant principles, state-of-the-art implementations, the status of current research and expected future components.

  11. 3D-printed PMMA Preform for Hollow-core POF Drawing

    DEFF Research Database (Denmark)

    Zubel, M. G.; Fasano, Andrea; Woyessa, Getinet

    2016-01-01

    In this paper we report the first, to our knowledge, 3D-printed hollow-core poly(methyl methacrylate) (PMMA) preform for polymer optical fibre drawing. It was printed of commercial PMMA by means of fused deposition modelling technique. The preform was drawn to cane, proving good enough quality...... of drawing process and the PMMA molecular weight to be appropriate for drawing. This ascertains that the manufacturing process provides preforms suitable for hollow-core fibre drawing. The paper focuses on maximisation of transparency of PMMA 3D printouts by optimising printing process parameters: nozzle...

  12. Special fibres and components

    DEFF Research Database (Denmark)

    Bunge, C.-A.; Woyessa, Getinet; Bremer, K.

    2017-01-01

    In this chapter we present more specific fibre types for particular applications. Starting with the multi-core fibre, which can be used as a substitution for ordinary SI-POF transmission fibres, but with better bending losses, over the ever increasing range of micro-structured POF for diverse...... sensing applications to fibres for illumination purposes or tubular fibres for the detection of sparks in electrical cables. Finally, a review on gratings in optical fibres and POFs in particular concludes the chapter. The different grating types, manufacturing methods and applications will be presented.​...

  13. Hollow-Core Fiber Lamp

    Science.gov (United States)

    Yi, Lin (Inventor); Tjoelker, Robert L. (Inventor); Burt, Eric A. (Inventor); Huang, Shouhua (Inventor)

    2016-01-01

    Hollow-core capillary discharge lamps on the millimeter or sub-millimeter scale are provided. The hollow-core capillary discharge lamps achieve an increased light intensity ratio between 194 millimeters (useful) and 254 millimeters (useless) light than conventional lamps. The capillary discharge lamps may include a cone to increase light output. Hollow-core photonic crystal fiber (HCPCF) may also be used.

  14. Fun with Optical Fibres

    Science.gov (United States)

    Alti, Kamlesh

    2017-01-01

    Optical fibres play a very crucial role in today's technologies. Academic courses in optical fibres start at the undergraduate level. Nevertheless, student's curiosity towards optical fibres starts from the school level. In this paper, some fun experiments have been designed for both school and college students, which have some concrete…

  15. How do Colluvial Hollows Fill?

    Science.gov (United States)

    Hales, T. C.; Parker, R.; Mudd, S. M.; Grieve, S. W. D.

    2016-12-01

    In humid, soil-mantled mountains shallow landslides commonly initiate in colluvial hollows, areas where convergent topography can lead to high pore pressures during storms. Immediately post-landslide initiation, a thin veneer of colluvial material accumulates by small-scale slumping from landslide headscarps. Thereafter colluvium accumulates in hollows primarily through creep-dominated processes like tree throw and animal burrowing, recording the hillslope sediment flux since the last landslide event. We measured the post-landslide hillslope sediment flux in 30 colluvial hollows in the southern Appalachians using radiocarbon measurements collected from soil pits excavated at the centre of steep, landslide-prone hollows. We collected material from the soil-saprolite/bedrock boundary at each location for radiocarbon dating and dated different chemical fractions of the soil (humic acid, humin, charcoal) in an attempt to bracket the "true" age of the soil. We calculated infilling rates of each hollow by measuring soil depths in cross-hollow transects and dividing this by the age of the hollow. The interquartile range of hollow basal ages is 2278-8184 cal. yrs B.P., demonstrating the long return period of landslides in most colluvial hollows. Hillslope erosion rates calculated assuming a linear diffusion transport law show that the transport coefficient (diffusivity) of the hollows varied by 4 orders of magnitude 10-5 to 10-1 m2 yr-1, despite the hollows being formed in regionally consistent geology and vegetation. Uncertainty in the dating and hollow geometry measurements can, at most, account for an order of magnitude of that variability. Our results show that hollows have a phase of rapid infilling that slows through time, consistent with previous observations. Despite this, the oldest hollows show several orders of magnitude variation in the transport coefficient, suggesting local, hollow scale variations in process significantly affect hillslope erosion rates.

  16. safety of carbon fibre reinforced plastic hollow sections in compression

    African Journals Online (AJOL)

    ADMINUSER

    2014-01-06

    Jan 6, 2014 ... researchers did a lot of work and study during the past few decades to investigate the durability of this ... performance of cross sections of columns subjected to combined shear and flexure stresses was ... models have been developed to describe the bond behaviour [11-14]. Other researches, primarily in ...

  17. High performance yttrium-doped BSCF hollow fibre membranes

    DEFF Research Database (Denmark)

    Haworth, P.; Smart, S.; Glasscock, Julie

    2012-01-01

    the oxygen flux significantly, from 4.9 to 7.0mlcm−2min−1 at 900°C for the BSCF and the BSCFY membranes, respectively. Permeation was particularly enhanced at lower temperatures, between 66% and 92% over the range 650–800°C. The lattice expansion determined from high temperature X-ray diffraction......-splitting was more pronounced for BSCFY, suggesting that the kinetics of the hexagonal phase formation may be faster for the yttrium-doped perovskite. The lattice volume of BSCFY expanded more than BSCF when exposed to nitrogen at 900°C, confirming a higher release of oxygen and enhanced oxygen non-stoichiometry....

  18. A microring multimode laser using hollow polymer optical fibre

    Indian Academy of Sciences (India)

    sealed and then it was filled with a mixture of monomer (MMA), 0.4 wt% of the polymerization initiator (benzoyl peroxide (BPO)), rhodamine B (10−4 m/l) and. 0.1 wt% of the chain transfer agent (n-butyl mercaptan). The polymerization was carried out at 80◦C for 48 h. The preform tube thus obtained was placed in an oven at ...

  19. Microstructured polymer optical fibres

    CERN Document Server

    Large, Maryanne; Barton, Geoff; van Eijkelenborg, Martijn A

    2008-01-01

    Microstructured Polymer Optical Fibres describes the optical properties of microstructured fibres, how they are made and modelled, and outlines some potential applications. These applications include areas where polymer fibres are already used, such as high-data rate transmission for Fibre-to-the Home or within cars, as well as completely new areas such as the photonic bandgap transmission of ""difficult"" wavelengths. Emphasising a conceptual understanding of the underlying physics, Microstructured Polymer Optical Fibres is clearly written, and includes numerous illustrations. It provides an

  20. Single-mode fibre coupler as refractometer sensor

    Indian Academy of Sciences (India)

    medium. Variation of refractive index as small as 0.001 RIU can be measured with our proposed sensor. Keywords. Fibre-optic sensor; intensity modulation; ... mode field distribution of the point source from the output port of a single-mode fibre .... Refractive index of propylene glycol can be varied by adding pure water.

  1. REVIEW ARTICLE Blue extension of optical fibre supercontinuum generation

    Science.gov (United States)

    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.

  2. Photonic Crystal Fibres

    DEFF Research Database (Denmark)

    Bjarklev, Anders Overgaard; Broeng, Jes; Sanchez Bjarklev, Araceli

    Photonic crystal fibres represent one of the most active research areas today in the field of optics. The diversity of applications that may be addressed by these fibres and their fundamental appeal, by opening up the possibility of guiding light in a radically new way compared to conventional...... optical fibres, have spun an interest from almost all areas of optics and photonics. The aim of this book is to provide an understanding of the different types of photonic crystal fibres and to outline some of the many new and exciting applications that these fibres offer. The book is intended for both...... bandgap structures and thoughts of inspiration from microstructures in nature, as well as classification of the various photonic crystal fibres, theoretical tools for analysing the fibres and methods of their production. Finally, the book points toward some of the many future applications, where photonic...

  3. Photonic Crystal Fibres

    DEFF Research Database (Denmark)

    Bjarklev, Anders Overgaard; Broeng, Jes; Sanchez Bjarklev, Araceli

    bandgap structures and thoughts of inspiration from microstructures in nature, as well as classification of the various photonic crystal fibres, theoretical tools for analysing the fibres and methods of their production. Finally, the book points toward some of the many future applications, where photonic......Photonic crystal fibres represent one of the most active research areas today in the field of optics. The diversity of applications that may be addressed by these fibres and their fundamental appeal, by opening up the possibility of guiding light in a radically new way compared to conventional...... optical fibres, have spun an interest from almost all areas of optics and photonics. The aim of this book is to provide an understanding of the different types of photonic crystal fibres and to outline some of the many new and exciting applications that these fibres offer. The book is intended for both...

  4. Fibre optic communication key devices

    CERN Document Server

    Grote, Norbert

    2017-01-01

    The book gives an in-depth description of key devices of current and next generation fibre optic communication networks. Devices treated include semiconductor lasers, optical amplifiers, modulators, wavelength filters and other passives, detectors, all-optical switches, but relevant properties of optical fibres and network aspects are included as well. The presentations include the physical principles underlying the various devices, technologies used for their realization, typical performance characteristics and limitations, but development trends towards more advanced components are also illustrated. This new edition of a successful book was expanded and updated extensively. The new edition covers among others lasers for optical communication, optical switches, hybrid integration, monolithic integration and silicon photonics. The main focus is on Indium phosphide-based structures but silicon photonics is included as well. The book covers relevant principles, state-of-the-art implementations, status of curren...

  5. Sweep gas membrane distillation in a membrane contactor with metallic hollow fibers

    NARCIS (Netherlands)

    Shukla, Sushumna; Benes, Nieck Edwin; Vankelecom, I.F.J.; Mericq, J.P.; Belleville, M.P.; Hengl, N.; Sanchez Marcano, Jose

    2015-01-01

    This work revolves around the use of porous metal hollow fibers in membrane distillation. Various stages are covered, starting from membrane synthesis up to the testing of a pilot scale membrane module. Mechanically stable metal hollow fibers have been synthesized by phase inversion of a stainless

  6. Experimental demonstration of a digital maximum likelihood based feedforward carrier recovery scheme for phase-modulated radio-over-fibre links

    DEFF Research Database (Denmark)

    Guerrero Gonzalez, Neil; Zibar, Darko; Yu, Xianbin

    2008-01-01

    Maximum likelihood based feedforward RF carrier synchronization scheme is proposed for a coherently detected phase-modulated radio-over-fiber link. Error-free demodulation of 100 Mbit/s QPSK modulated signal is experimentally demonstrated after 25 km of fiber transmission.......Maximum likelihood based feedforward RF carrier synchronization scheme is proposed for a coherently detected phase-modulated radio-over-fiber link. Error-free demodulation of 100 Mbit/s QPSK modulated signal is experimentally demonstrated after 25 km of fiber transmission....

  7. Hollow Microporous Organic Capsules

    Science.gov (United States)

    Li, Buyi; Yang, Xinjia; Xia, Lingling; Majeed, Muhammad Irfan; Tan, Bien

    2013-01-01

    Fabrication of hollow microporous organic capsules (HMOCs) could be very useful because of their hollow and porous morphology, which combines the advantages of both microporous organic polymers and non-porous nanocapsules. They can be used as storage materials or reaction chambers while supplying the necessary path for the design of controlled uptake/release systems. Herein, the synthesis of HMOCs with high surface area through facile emulsion polymerization and hypercrosslinking reactions, is described. Due to their tailored porous structure, these capsules possessed high drug loading efficiency, zero-order drug release kinetics and are also demonstrated to be used as nanoscale reactors for the prepareation of nanoparticles (NPs) without any external stabilizer. Moreover, owing to their intrinsic biocompatibility and fluorescence, these capsules exhibit promising prospect for biomedical applications. PMID:23820511

  8. Hollow bunches production

    CERN Document Server

    Hancock, S

    2017-01-01

    Hollow bunches address the issue of high-brightnessbeams suffering from transverse emittance growth in a strongspace charge regime. During the Proton Synchrotron (PS)injection plateau, the negative space charge tune shift canpush the beam onto theQy=6integer resonance. Modify-ing the longitudinal bunch profile in order to reduce the peakline charge density alleviates the detrimental impact of spacecharge. To this end we first produce longitudinally hollowphase space distributions in the PS Booster by exciting aparametric resonance with the phase loop feedback system.These inherently flat bunches are then transferred to the PS,where the beam becomes less prone to the emittance growthcaused by the integer resonance.During the late 2016 machine development sessions inthe PS Booster we profited from solved issues from 2015and managed to reliably extract hollow bunches of1.3eVsmatched longitudinal area. Furthermore, first results to cre-ate hollow bunches with larger longitudinal emittances to-wards the LHC Inject...

  9. Fibre-optic nonlinear optical microscopy and endoscopy.

    Science.gov (United States)

    Fu, L; Gu, M

    2007-06-01

    Nonlinear optical microscopy has been an indispensable laboratory tool of high-resolution imaging in thick tissue and live animals. Rapid developments of fibre-optic components in terms of growing functionality and decreasing size provide enormous opportunities for innovations in nonlinear optical microscopy. Fibre-based nonlinear optical endoscopy is the sole instrumentation to permit the cellular imaging within hollow tissue tracts or solid organs that are inaccessible to a conventional optical microscope. This article reviews the current development of fibre-optic nonlinear optical microscopy and endoscopy, which includes crucial technologies for miniaturized nonlinear optical microscopy and their embodiments of endoscopic systems. A particular attention is given to several classes of photonic crystal fibres that have been applied to nonlinear optical microscopy due to their unique properties for ultrashort pulse delivery and signal collection. Furthermore, fibre-optic nonlinear optical imaging systems can be classified into portable microscopes suitable for imaging behaving animals, rigid endoscopes that allow for deep tissue imaging with minimally invasive manners, and flexible endoscopes enabling imaging of internal organs. Fibre-optic nonlinear optical endoscopy is coming of age and a paradigm shift leading to optical microscope tools for early cancer detection and minimally invasive surgery.

  10. Scintillating fibre (SciFi) tracker

    CERN Multimedia

    Caraban Gonzalez, Noemi

    2017-01-01

    128 modules – containing 11 000 km of scintillating fibres – will make up the new SciFi tracker, which will replace the outer and inner trackers of the LHCb detector as part of the experiment’s major upgrade during Long Shutdown 2 (LS2)

  11. Measuring method for optical fibre sensors

    NARCIS (Netherlands)

    Lammerink, Theodorus S.J.; Fluitman, J.H.J.

    1984-01-01

    A new measuring method for the signal amplitude in intensity modulating fibre optic sensors is described. A reference signal is generated in the time domain. The method is insensitive for the sensitivity fluctuations of the light transmitter and the light receiver. The method is experimentally

  12. Towards high-capacity fibre-optic communications at the speed of light in vacuum

    Science.gov (United States)

    Poletti, F.; Wheeler, N. V.; Petrovich, M. N.; Baddela, N.; Numkam Fokoua, E.; Hayes, J. R.; Gray, D. R.; Li, Z.; Slavík, R.; Richardson, D. J.

    2013-04-01

    Wide-bandwidth signal transmission with low latency is emerging as a key requirement in a number of applications, including the development of future exaflop-scale supercomputers, financial algorithmic trading and cloud computing. Optical fibres provide unsurpassed transmission bandwidth, but light propagates 31% slower in a silica glass fibre than in vacuum, thus compromising latency. Air guidance in hollow-core fibres can reduce fibre latency very significantly. However, state-of-the-art technology cannot achieve the combined values of loss, bandwidth and mode-coupling characteristics required for high-capacity data transmission. Here, we report a fundamentally improved hollow-core photonic-bandgap fibre that provides a record combination of low loss (3.5 dB km-1) and wide bandwidth (160 nm), and use it to transmit 37 × 40 Gbit s-1 channels at a 1.54 µs km-1 faster speed than in a conventional fibre. This represents the first experimental demonstration of fibre-based wavelength division multiplexed data transmission at close to (99.7%) the speed of light in vacuum.

  13. Ion Implantation In Optical Fibres

    Science.gov (United States)

    McStay, Daniel

    1989-10-01

    Some initial results on the implantation of single- and multi-mode optical fibres are described. Fibres are wound onto a bobin system for insertion into the implantation chamber. Long and short lengths of fibres as well as discrete elements along a fibre have been implanted. Refractive index changes of 5 x 10-3 have been produced in the fibres, leading to new guiding properties. A large dose dependent fluorescence and attenuation increase is also produced in the fibre.

  14. Supercontinuum generation in photonic crystal fibres

    DEFF Research Database (Denmark)

    Frosz, Michael Henoch

    2007-01-01

    characterization, spectroscopy, optical communications, and optical coherence tomography (OCT). This thesis presents a study of SCG in photonic crystal fibre (PCF) using numerical modelling. The nonlinear physical mechanisms relevant for the thesis are reviewed. It is investigated how the SC spectrum can be shaped...... by self-phase modulation in the first millimetres of the fibre, followed by soliton red-shift. The soliton red-shift is limited by the higher ZDW and the generation of dispersive waves. The first observation of an apparent bright-bright soliton pair across the ZDW is also reported. For picosecond pumping...

  15. fibres via electrospinning

    Indian Academy of Sciences (India)

    The Fourier transform infrared spectroscopy (FTIR) indicated that the structure of NaPSS did not change after electrospinning. Keywords. NaPSS; ultrafine fibre; electrospinning; SEM; FTIR. 1. Introduction ... pore size (Park et al 2004). Many polymers have been spun into fibres by electrospinning (Kim et al 2005; Zhou et al.

  16. The reinforcement and healing of asphalt mastic mixtures by rejuvenator encapsulation in alginate compartmented fibres

    Science.gov (United States)

    Tabaković, A.; Post, W.; Cantero, D.; Copuroglu, O.; Garcia, S. J.; Schlangen, E.

    2016-08-01

    This paper explores the potential use of compartmented alginate fibres as a new method of incorporating rejuvenators into asphalt pavement mixtures. The compartmented fibres are employed to locally distribute the rejuvenator and to overcome the problems associated with spherical capsules and hollow fibres. The work presents proof of concept of the encapsulation process which involved embedding the fibres into the asphalt mastic mixture and the survival rate of fibres in the asphalt mixture. To prove the effectiveness of the alginate as a rejuvenator encapsulating material and to demonstrate its ability survive asphalt production process, the fibres containing the rejuvenator were prepared and subjected to thermogravimetric analysis and uniaxial tensile test. The test results demonstrated that fibres have suitable thermal and mechanical strength to survive the asphalt mixing and compaction process. The CT scan of an asphalt mortar mix containing fibres demonstrated that fibres are present in the mix in their full length, undamaged, providing confirmation that the fibres survived the asphalt production process. In order to investigate the fibres physiological properties and ability to release the rejuvenator into cracks in the asphalt mastic, the environmental scanning electron microscope and optical microscope analysis were employed. To prove its success as an asphalt healing system, compartmented alginate fibres containing rejuvenator were embedded in asphalt mastic mix. The three point bend tests were performed on the asphalt mastic test samples and the degree to which the samples began to self-heal in response was measured and quantified. The research findings indicate that alginate fibres present a promising new approach for the development of self-healing asphalt pavement systems.

  17. Birefringent hollow core fibers

    DEFF Research Database (Denmark)

    Roberts, John

    2007-01-01

    Hollow core photonic crystal fiber (HC-PCF), fabricated according to a nominally non-birefringent design, shows a degree of un-controlled birefringence or polarization mode dispersion far in excess of conventional non polarization maintaining fibers. This can degrade the output pulse in many...... and an increased overlap between the polarization modes at the glass interfaces. The interplay between these effects leads to a wavelength for optimum polarization maintenance, lambda(PM), which is detuned from the wavelength of highest birefringence. By a suitable fiber design involving antiresonance of the core...

  18. Osmotic distillation and quality evaluation of sucrose, apple and orange juices in hollow fiber membrane contactor

    Directory of Open Access Journals (Sweden)

    Rehman Waheed Ur

    2017-01-01

    Full Text Available Sucrose solution, apple and orange juices were concentrated through osmotic distillation (OD process using a mini-module Liqui-CelTM hollow fibre membrane contactor. Mass transport characteristics of water molecules from feed to stripping solution were studied. Process parameters such as feed temperature, feed flow rate and concentration of stripping solution (CaCl2 were varied. Sucrose solution was concentrated from 135 to 510 g TSS kg-1 in 340 min using feed-in- -lumen flow configuration at a start-up water flux of 0.250 L m-2 h-1 and a temperature of 30°C. Similarly, it was concentrated up to 510 g TSS kg-1 in 200 min using feed-in-shell flow configuration at a start-up water flux of 0.505 L m-2 hr1 and a temperature of 30°C. In a total recycle time of 340 min, clarified apple and orange juices were concentrated up to 500 g TSS kg-1 using feed-in-lumen flow configuration at a start-up water flux of 0.204 and 0.294 L m-2 hr1, respectively. It was found that quality parameters of fruit juices were well improved after the osmotic distillation process. The process therefore has good potential for application in the fruit processing industry for concentration of fruit juices.

  19. Photonic Crystal Fibres

    DEFF Research Database (Denmark)

    Bjarklev, Anders Overgaard; Broeng, Jes; Sanchez Bjarklev, Araceli

    Photonic crystal fibres represent one of the most active research areas today in the field of optics. The diversity of applications that may be addressed by these fibres and their fundamental appeal, by opening up the possibility of guiding light in a radically new way compared to conventional...... optical fibres, have spun an interest from almost all areas of optics and photonics. The aim of this book is to provide an understanding of the different types of photonic crystal fibres and to outline some of the many new and exciting applications that these fibres offer. The book is intended for both...... readers with a general interest in photonic crystals, as well as for scientists who are entering the field and desire a broad overview as well as a solid starting point for further specialized stuides. Teh book, therefore, covers bothe general aspects such as the link from classical optics to photonic...

  20. On defining dietary fibre.

    Science.gov (United States)

    DeVries, Jonathan W

    2003-02-01

    Establishing a definition for dietary fibre has historically been a balance between nutrition knowledge and analytical method capabilities. While the most widely accepted physiologically-based definitions have generally been accurate in defining the dietary fibre in foods, scientists and regulators have tended, in practice, to rely on analytical procedures as the definitional basis in fact. As a result, incongruities between theory and practice have resulted in confusion regarding the components that make up dietary fibre. In November 1998 the president of the American Association of Cereal Chemists (AACC) appointed an expert scientific review committee and charged it with the task of reviewing and, if necessary, updating the definition of dietary fibre. The committee was further charged with assessing the state of analytical methodology and making recommendations relevant to the updated definition. After due deliberation, an updated definition of dietary fibre was delivered to the AACC Board of Directors for consideration and adoption (Anon, 2000; Jones 2000b). The updated definition includes the same food components as the historical working definition used for approximately 30 years (a very important point, considering that the majority of the research of the past 30 years delineating the positive health effects of dietary fibre is based on that working definition). However, the updated definition more clearly delineates the make-up of dietary fibre and its physiological functionality. As a result, relatively few changes will be necessary in analytical methodology. Current methodologies, in particular AACC-approved method of analysis 32-05 (Grami, 2000), Association of Official Analytical Chemists' official method of analysis 985.29 (Horwitz, 2000a) or AACC 32-07 (Grami, 2000) Association of Official Analytical Chemists 991.43 (Horwitz, 2000a) will continue to be sufficient and used for most foods. A small number of additional methods will be necessary to

  1. Dietary fibre analysis.

    Science.gov (United States)

    McCleary, Barry V

    2003-02-01

    The 'gold standard' method for the measurement of total dietary fibre is that of the Association of Official Analytical Chemists (2000; method 985.29). This procedure has been modified to allow measurement of soluble and insoluble dietary fibre, and buffers employed have been improved. However, the recognition of the fact that non-digestible oligosaccharides and resistant starch also behave physiologically as dietary fibre has necessitated a re-examination of the definition of dietary fibre, and in turn, a re-evaluation of the dietary fibre methods of the Association of Official Analytical Chemists. With this realisation, the American Association of Cereal Chemists appointed a scientific review committee and charged it with the task of reviewing and, if necessary, updating the definition of dietary fibre. It organised various workshops and accepted comments from interested parties worldwide through an interactive website. More recently, the (US) Food and Nutrition Board of the Institute of Health, National Academy of Sciences, under the oversight of the Standing Committee on the Scientific Evaluation of Dietary Reference Intakes, assembled a panel to develop a proposed definition(s) of dietary fibre. Various elements of these definitions were in agreement, but not all. What was clear from both reviews is that there is an immediate need to re-evaluate the methods that are used for dietary fibre measurement and to make appropriate changes where required, and to find new methods to fill gaps. In this presentation, the 'state of the art' in measurement of total dietary fibre and dietary fibre components will be described and discussed, together with suggestions for future research.

  2. Comportement à la corrosion galvanique de matériaux composites à matrice d'alliage d'aluminium renforcée par des fibres de carbone haut-module

    OpenAIRE

    Payan, Sandrine

    2001-01-01

    The service behaviour analysis of aluminium matrix composite material reinforced with carbon fibre involves evaluating the corrosion evaluation in a saline environment. The galvanic coupling between the carbon fibres and the aluminium alloy matrix plays a main part in the degradation of these composite materials. A local analysis by an in-situ experimental approach and a semi-analytical modelling are proposed to study the corrosion initiation and propagation at the fibre/matrix interfaces. Th...

  3. Active combustion flow modulation valve

    Science.gov (United States)

    Hensel, John Peter; Black, Nathaniel; Thorton, Jimmy Dean; Vipperman, Jeffrey Stuart; Lambeth, David N; Clark, William W

    2013-09-24

    A flow modulation valve has a slidably translating hollow armature with at least one energizable coil wound around and fixably attached to the hollow armature. The energizable coil or coils are influenced by at least one permanent magnet surrounding the hollow armature and supported by an outer casing. Lorentz forces on the energizable coils which are translated to the hollow armature, increase or decrease the flow area to provide flow throttling action. The extent of hollow armature translation depends on the value of current supplied and the direction of translation depends on the direction of current flow. The compact nature of the flow modulation valve combined with the high forces afforded by the actuator design provide a flow modulation valve which is highly responsive to high-rate input control signals.

  4. Optical fibre microwire sensors

    OpenAIRE

    Brambilla, G.; Belal, Mohammad; Jung, Y.; Song, Z.; Xu, F.; Newson, T.P.; Richardson, D.J.

    2011-01-01

    This paper reviews sensing applications of optical fibre microwires and nanowires. In addition to the usual benefits of sensors based on optical fibres, these sensors are extremely compact and have fast response speeds. In this review sensors will be grouped in three categories according to their morphology: linear sensors, resonant sensors and tip sensors. While linear and resonant sensors mainly exploit the fraction of power propagating outside the microwire physical boundary, tip sensors t...

  5. Fibre Concrete 2017

    Science.gov (United States)

    2017-09-01

    9th international conference on fibre reinforced concretes (FRC), textile reinforced concretes (TRC) and ultra-high performance concretes (UHPC) Preface The Fibre Concrete Conference series is held biennially to provide a platform to share knowledge on fibre reinforced concretes, textile concretes and ultra-high performance concretes regarding material properties and behaviour, technology procedures, topics of long-term behaviour, creep, durability; sustainable aspects of concrete including utilisation of waste materials in concrete production and recycling of concrete. The tradition of Fibre Concrete Conferences started in eighties of the last century. Nowadays the conference is organized by the Department of Concrete and Masonry Structures of the Czech Technical University in Prague, Faculty of Civil Engineering. The 9th International Conference Fibre Concrete 2017 had 109 participants from 27 countries all over the world. 55 papers were presented including keynote lectures of Professor Bažant, Professor Bartoš and Dr. Broukalová. The conference program covered wide range of topics from scientific research to practical applications. The presented contributions related to performance and behaviour of cement based composites, their long-term behaviour and durability, sustainable aspects, advanced analyses of structures from these composites and successful applications. This conference was organized also to honour Professor Zděnek P. Bažant on the occasion of his jubilee and to appreciate his merits and discoveries in the field of fibre reinforced composites, structural mechanics and engineering.

  6. Nonlinear resonance phenomena of a doped fibre laser under cavity ...

    Indian Academy of Sciences (India)

    Under suitable time-sustained perturba- tions, such as periodic parameter modulation, injection of external light and feed- back, these lasers can exhibit salient ... of chaos and synchronization of coupled chaotic lasers (for communication with a chaotic carrier). In recent years, fibre lasers pumped by periodically modulated ...

  7. Detritiation of water using microporous hollow-fiber membranes

    Energy Technology Data Exchange (ETDEWEB)

    Kelso, R.C. [Nevada Division of Environmental Protection, Carson City, NV (United States); Ahmed, T.; Middlebrooks, E.J. [Univ. of Nevada, Reno, NV (United States)

    1997-03-01

    A novel concept of tritium (HTO) removal with microporous hollow fiber membranes was evaluated in this study. Small-scale laboratory modules were constructed and tested to determine the mass transfer characteristics of the hollow fibers under varying system parameters. Tritiated water is pumped through the fiber lumen and air, saturated with water vapor, is pumped over the exterior of the fibers in a countercurrent mode. The high HTO concentration gradient encourages the HTO to diffuse across the porous membrane wall, and to transfer directly into the saturated air stream. A dimensionless mathematical correlation that predicts the tritium transfer coefficient across the membranes is presented for parallel flow modules. The measured overall mass transfer coefficients in the membrane module are two to three orders of magnitude greater than those of conventional bubble stripping. In additions, factors that influence the mass transfer performance of the membrane modules in practical applications are evaluated. The results indicate that very low concentrations of HTO can be separated from water using microporous hollow fiber membranes. 33 refs., 8 figs., 3 tabs.

  8. Hollow fiber adsorbents for CO2 capture: Kinetic sorption performance

    KAUST Repository

    Lively, Ryan P.

    2011-07-01

    We describe a CO 2 capture platform based on hollow polymeric fibers with sorbent particles embedded in the porous fiber wall for post-combustion CO 2 capture. These fibers are intended for use in a rapid temperature swing adsorption (RTSA) process. The RTSA system utilizes the hollow fiber morphology by flowing cooling water on the bore-side of the fibers during sorption to prevent temperature rise associated with the sorption enthalpy. Steam or hot water is flowed through the bores during desorption to desorb CO 2 rapidly. To minimize material transfer between the bore and the fiber wall, a dense Neoprene ® lumen layer is cast on the bore-side of the fiber wall. In this paper, the key sorption step and associated kinetic resistances for the uncooled fibers are examined and evaluated for this portion of the RTSA process. Chopped fibers in a packed bed, as well as fibers assembled into a parallel flow module, have been tested in a simulated flue gas stream. Kinetic limitations in the hollow fiber modules are largely overcome by increasing the superficial gas velocity and the fiber packing in the module-indicating that film diffusion is the controlling mass transfer limitation in the fiber system. The un-cooled fiber modules lose apparent capacity as superficial velocities are increased, likely indicating non-isothermal operation, whereas the actively-cooled fibers in the packed bed maintain apparent capacity at all flowrates studied. © 2011 Elsevier B.V.

  9. Modelling of photonic crystal fibres

    DEFF Research Database (Denmark)

    Knudsen, Erik

    2003-01-01

    In the presenta ph.d. work a theoretical study of aspects of modelling photonic crystal fibres was carried out. Photonic crystal fibres form a class of optical waveguides where guidance is no longer provided by a difference in refractive index between core and cladding. Instead, guidance...... is provided by an arrangement of air-holes running along the length of the fibre. Depending on the geometry of the fibre, the guiding mechanism may be either arising from the formation of a photonic bandgap in the cladding structure (photonic bandgap fibre), or by an effect resembling total internal...... reflection, which may described by an effective refractive index which is lower in the cladding than in the core (index guiding fibre). By solving Maxwell's equations, under the conditions defined by the geometry of the fibre structure, we may predict the properties of the fibre. In all but rare cases...

  10. Multibeam Fibre Laser Cutting

    DEFF Research Database (Denmark)

    Olsen, Flemming Ove

    The appearance of the high power high brilliance fibre laser has opened for new possibilities in laser materials processing. In laser cutting this laser has demonstrated high cutting performance compared to the dominating cutting laser, the CO2-laser. However, quality problems in fibre......-laser cutting have until now limited its application in metal cutting. In this paper the first results of proof-of-principle studies applying a new approach (patent pending) for laser cutting with high brightness short wavelength lasers will be presented. In the approach, multi beam patterns are applied...... to control the melt flow out of the cut kerf resulting in improved cut quality in metal cutting. The beam patterns in this study are created by splitting up beams from 2 single mode fibre lasers and combining these beams into a pattern in the cut kerf. The results are obtained with a total of 550 W of single...

  11. Beam steering by liquid crystal elastomer fibres.

    Science.gov (United States)

    Nocentini, S; Martella, D; Wiersma, D S; Parmeggiani, C

    2017-11-22

    The problem of utilizing a laser beam as an information vehicle and dividing it into different channels is an open problem in the telecommunication field. The switching of a signal into different ports has been demonstrated, to date, by employing complex devices and mechanisms such as the electro optic effect, microelectromechanical system (MEMS) mirrors, or liquid crystal-based spatial light modulators (SLMs). We present here a simple device, namely a mirror held by a liquid crystal elastomer (LCE) fibre, as an optically and remotely driven beam steerer. In fact, a considered signal (laser beam) can be addressed in every in-plane direction by controlling the fibre and mirror rotation, i.e., the deflected probe beam angle. Such movement is possible due to the preparation of LCE fibres able to rotate and contract under a selective light stimulus. By adjusting the irradiation stimulus power, elastic fibres are able to rotate with a specific angle, performing more than one complete revolution around their axis. The described movement is perfectly reversible as soon as the stimulus is removed.

  12. Single-mode optical fibres

    CERN Document Server

    Cancellieri, G

    1991-01-01

    This book describes signal propagation in single-mode optical fibres for telecommunication applications. Such description is based on the analysis of field propagation, considering waveguide properties and also some of the particular characteristics of the material fibre. The book covers such recent advances as, coherent transmissions; optical amplification; MIR fibres; polarization maintaining; polarization diversity and photon counting.

  13. The influence of electrospun fibre size on Schwann cell behaviour and axonal outgrowth

    Energy Technology Data Exchange (ETDEWEB)

    Gnavi, S., E-mail: sara.gnavi@unito.it [Department of Clinical and Biological Sciences, University of Torino, Orbassano 10043 (Italy); Neuroscience Institute of the Cavalieri-Ottolenghi Foundation, University of Torino, Orbassano 10043 (Italy); Fornasari, B.E., E-mail: benedettaelena.fornasari@unito.it [Department of Clinical and Biological Sciences, University of Torino, Orbassano 10043 (Italy); Neuroscience Institute of the Cavalieri-Ottolenghi Foundation, University of Torino, Orbassano 10043 (Italy); Tonda-Turo, C., E-mail: chiara.tondaturo@polito.it [Politecnico di Torino, Department of Mechanical and Aerospace Engineering, Politecnico of Torino, Torino 10100 (Italy); Ciardelli, G., E-mail: gianluca.ciardelli@polito.it [Politecnico di Torino, Department of Mechanical and Aerospace Engineering, Politecnico of Torino, Torino 10100 (Italy); CNR-IPCF UOS, Pisa 56124 (Italy); Zanetti, M., E-mail: marco.zanetti@unito.it [Nanostructured Interfaces and Surfaces, Department of Chemistry, University of Torino, Torino 10100 (Italy); Geuna, S., E-mail: stefano.geuna@unito.it [Department of Clinical and Biological Sciences, University of Torino, Orbassano 10043 (Italy); Neuroscience Institute of the Cavalieri-Ottolenghi Foundation, University of Torino, Orbassano 10043 (Italy); Perroteau, I., E-mail: isabelle.perroteau@unito.it [Department of Clinical and Biological Sciences, University of Torino, Orbassano 10043 (Italy)

    2015-03-01

    Fibrous substrates functioning as temporary extracellular matrices can be prepared easily by electrospinning, yielding fibrous matrices suitable as internal fillers for nerve guidance channels. In this study, gelatin micro- or nano-fibres were prepared by electrospinning by tuning the gelatin concentration and solution flow rate. The effect of gelatin fibre diameter on cell adhesion and proliferation was tested in vitro using explant cultures of Schwann cells (SC) and dorsal root ganglia (DRG). Cell adhesion was assessed by quantifying the cell spreading area, actin cytoskeleton organization and focal adhesion complex formation. Nano-fibres promoted cell spreading and actin cytoskeleton organization, increasing cellular adhesion and the proliferation rate. However, both migration rate and motility, quantified by transwell and time lapse assays respectively, were greater in cells cultured on micro-fibres. Finally, there was more DRG axon outgrowth on micro-fibres. These data suggest that the topography of electrospun gelatin fibres can be adjusted to modulate SC and axon organization and that both nano- and micro-fibres are promising fillers for the design of devices for peripheral nerve repair. - Highlights: • Electrospinning used to produce gelatin nano- and micro-fibre matrices. • Nano-fibre matrices promote Schwann cell organization and increase proliferation rate. • Micro-fibre matrices promote Schwann cell migration. • Micro-fibre matrices promote axonal outgrowth.

  14. Hollow waveguide for urology treatment

    Science.gov (United States)

    Jelínková, H.; Němec, M.; Koranda, P.; Pokorný, J.; Kőhler, O.; Drlík, P.; Miyagi, M.; Iwai, K.; Matsuura, Y.

    2010-02-01

    The aim of our work was the application of the special sealed hollow waveguide system for the urology treatment - In our experimental study we have compared the effects of Ho:YAG (wavelength 2100 nm) and Er:YAG (wavelength 2940 nm) laser radiation both on human urinary stones (or compressed plaster samples which serve as a model) fragmentation and soft ureter tissue incision in vitro. Cyclic Olefin Polymer - coated silver (COP/Ag) hollow glass waveguides with inner and outer diameters 700 and 850 μm, respectively, were used for the experiment. To prevent any liquid to diminish and stop the transmission, the waveguide termination was utilized.

  15. Quartz antenna with hollow conductor

    Science.gov (United States)

    Leung, Ka-Ngo; Benabou, Elie

    2002-01-01

    A radio frequency (RF) antenna for plasma ion sources is formed of a hollow metal conductor tube disposed within a glass tube. The hollow metal tubular conductor has an internal flow channel so that there will be no coolant leakage if the outer glass tube of the antenna breaks. A portion of the RF antenna is formed into a coil; the antenna is used for inductively coupling RF power to a plasma in an ion source chamber. The antenna is made by first inserting the metal tube inside the glass tube, and then forming the glass/metal composite tube into the desired coil shape.

  16. sisal fibre- epoxy compos

    African Journals Online (AJOL)

    eobe

    2015-10-04

    Oct 4, 2015 ... composition of kaolin is presented in Table 1. The use of epoxy resin in composite studies is quite extensive [31-33]. Epoxies find application in metal coatings, electronic and electrical components, high- tension electrical insulators, fibre-reinforced plastic/composite materials and structured adhesives. [33].

  17. Glass Fibre Reinforced Polymers

    NARCIS (Netherlands)

    Nikolaou, N.; Karagianni, L.; Sarakiniatti, M.V.

    2014-01-01

    This "designers' manual" is made during the TIDO-course AR0533 Innovation & Sustainability. Fibre reinforced polymers (FRPs) have been used in many applications over the years, from new construction to retrofitting. They are lightweight, no-corrosive, exhibit high specific strength and specific

  18. D fibre antenna for microcellular communications

    CERN Document Server

    Bhatti, A A

    2003-01-01

    Over the years, optical fibre sensors have been developed for many application areas. With the recent growth of microcellular communication systems this area has great economic potential. Therefore with this in mind one promising application for a new optical fibre sensor system is in the detection of Radio Frequency/Electric Fields (RF/EF). By constructing such a sensor from totally dielectric materials, it could be used as an antenna for receiving radio frequency transmissions without distorting or disturbing the field lines since there are no metallic components to reflect or transmit radio frequency energy. One of the key issues in the realisation of Radio-over-Fibre (RoF) architecture is the development of an effective means of generating and transmitting the radio subcarrier. The simplest method for the optical generation of radio signals, for transmission through an optical network is to directly modulate the light source with the received RF signal. Direct modulation of the laser can lead to a number ...

  19. Fabrication and characterization of functionally graded poly(vinylidine fluoride)-silver nanocomposite hollow fibers for sustainable water recovery

    KAUST Repository

    Francis, Lijo

    2014-12-01

    Poly(vinylidine fluoride) (PVDF) asymmetric hydrophobic hollow fibers were fabricated successfully using dryjet wet spinning. Hydrophobic silver nanoparticles were synthesized and impregnated into the PVDF polymer matrix and functionally graded PVDF-silver nanocomposite hollow fibers are fabricated and tested in the direct contact membrane distillation (DCMD) process. The as-synthesized silver nanoparticles were characterized for Transmission Electron Microscopy (TEM), particle size distribution (PSD) and Ultra Violet (UV) visible spectroscopy. Both the PVDF and PVDF-silver nanocomposite asymmetric hollow fibers were characterized for their morphology, water contact angle and mechanical strength. Addition of hydrophobic silver nanoparticles was found to enhance the hydrophobicity and ~ 2.5 fold increase the mechanical strength of the hollow fibers. A water vapor flux of 31.9kg m-2 h-1 was observed at a feed inlet temperature of 80 °C and at a permeate temperature of 20 °C in the case of hollow fiber membrane modules fabricated using PVDF hollow fibers; the water vapor flux was found to be increased by about 8% and to reach 34.6kg m-2 h-1 for the hollow fiber membrane modules fabricated from the PVDF-silver nanocomposite hollow fibers at the same operating conditions with 99.99% salt rejection.

  20. Hollow Force, Hollow Metaphor: Assessing The Current Defense Drawdown

    Science.gov (United States)

    2016-04-04

    of a period of war and the threats diminish and everyone starts cutting the hell out of the defense budget….we are not going to hollow out the force...and tactical unit performance at the National Training Center. Henderson concluded that structural barriers and adopted practices in the new All

  1. Immunomodulatory effects of mineral fibres in occupationally exposed workers.

    Science.gov (United States)

    Tulinska, Jana; Jahnova, Eva; Dusinska, Maria; Kuricova, Miroslava; Liskova, Aurelia; Ilavska, Silvia; Horvathova, Mira; Wsolova, Ladislava; Kyrtopoulos, Soterios A; Collins, Andrew; Harrington, Vikki; Fuortes, Laurence

    2004-09-03

    In the context of a large-scale molecular epidemiology study, the possible immunomodulatory effects of mineral fibres, in workers occupationally exposed to asbestos, rockwool and glass fibres, were examined. In each plant, 61, 98 and 80 exposed workers and 21, 43 or 36 control clerical subjects, respectively, were recruited. In the case of the asbestos-exposed subjects, an additional town-control group of 49 people was included. Evidence of pulmonary fibrosis was found in 42% of the asbestos-exposed workers, while evidence of pleural fibrosis was found in 24%. The asbestos-exposed cohort had significantly decreased forced vital capacity of lungs as well as forced expiratory volume per first second. Our findings indicate that exposure to all three types of fibres examined modulates to different degrees the immune response. Suppression of T-cell immunity and to a lesser extent, B-cell immunity was found in the case of workers from a former asbestos cement plant, while stimulation of T-cell response was observed in rockwool workers, and stimulation of T- and B-cell response was seen in glass fibre workers. Depression of the percentage of lymphocyte subpopulation of CD 16+56 (natural killer cells) in peripheral blood was found in glass fibre workers. Statistical analysis showed increased levels of proinflammatory cytokines (IL-6 asbestos; IL-8 all three fibres), expression of adhesion molecule L-selectin on granulocytes and monocytes (asbestos), levels of soluble adhesion molecules (SAMs) in sera (ICAM-1 all three fibres; E-selectin glass fibres), increased levels of immunoglobulin E (asbestos and rockwool) and elevated expression of activation markers on eosinophils (CD66b asbestos, glass fibres; CD69 asbestos). Significant correlations were observed between lymphocyte proliferation and markers of DNA damage and repair. Increased levels of proinflammatory cytokines, SAMs, immunoglobulin E and elevated expression of activation markers on eosinophils was found in people

  2. Effect of triggering angles on the crushing mechanisms of hybrid woven kenaf/aluminum hollow cylinders

    Science.gov (United States)

    Ismail, Al Emran; Mat Noor, Fazimah; Mohamad, Zaleha; Amran Madlan, Mohd; Zulafif Rahim, M.; Rasidi Ibrahim, M.; Ahmad, Sufizar; Nasrull Abdol Rahman, Mohd; Salleh, Salihatun Md; Sadikin, Azmahani; Mahzan, Shahruddin; Nor, Nik Hisyamudin Muhd

    2017-10-01

    This paper presents the effect of triggering angles constructed on the top of hybrid woven kenaf/aluminium hollow cylinders on the energy absorption performances. The crushing performances of aluminium tubes can be found widely in open literature. However, lack number of work on the hybridizing the aluminium tubes with woven kenaf fibre is found. Woven kenaf mats are produced and bathed with polymeric resin before they are wrapped around the aluminium tubes twice. Different fibre orientations, ±θ° are used where θ = 0, 15, 30 and 45. Once the hybrid composite hardened, one of their end are chamfered using different angles of 0°, 30°, 45° and 60°. The tubes are quasi-statically compressed in order to obtain their force-displacement responses and crashworthiness parameters are extracted and discussed with the relation of fibre orientations and chamfering angles. It is found that the chamfering angles are only affected the force-displacement curves during the first stage of elastic deformation whereas there is no obvious effect in the second stage. However, varying the fibre orientations are slightly increased the force-displacement curves especially when the fibre is orientated with 30°. Based on the fracture mechanism observations, most of composite experienced large fragmentation indicating that the composites absorbed the crushing energy ineffectively.

  3. Nitric oxide synthase in human skeletal muscles related to defined fibre types.

    Science.gov (United States)

    Punkt, Karla; Fritzsche, Matthias; Stockmar, Christoph; Hepp, Pierre; Josten, Christoph; Wellner, Maren; Schering, Stefan; Buchwalow, Igor B

    2006-05-01

    Skeletal muscle functions regulated by NO are now firmly established. However, the knowledge about the NO synthase (NOS) expression related to a defined fibre type in human skeletal muscles necessitates further clarification. To address this issue, we examined localization of NOS isoforms I, II and III, in human skeletal muscles employing immunocytochemical labeling with tyramide signal amplification complemented with enzyme histochemistry and Western blotting. The NOS immunoreactivity was related to fibre types of different classification systems: physiological classification into slow and fast, ATPase classification into I, IIA, IIAX, IIX, and physiological-metabolic classification into slow-oxidative (SO), fast-oxidative glycolytic (FOG) and fast-glycolytic (FG). We found a correlation of NOS I-III immunoreactivity to metabolic defined fibre types with strong expression in FOG fibres. This implies that NO as modulator of muscle function is involved in oxidative metabolism in connection with fast force development, which only occurs in FOG fibres. The NOS expression showed no correlation to ATPase fibre subtypes due to the metabolic heterogeneity of ATPase fibre types. Healthy and affected vastus medialis muscles after anterior cruciate ligament rupture revealed similar NOS expression level as shown by Western blotting with, however, different expression patterns related to the fibre types in affected muscles. This suggests an altered modulation of force development in the fibres of diseased muscles.

  4. Optical Fibre Bundle

    CERN Multimedia

    These are sample fibre optic cables which are used for networking. Optical fibers are widely used in fiber-optic communications, where they permit transmission over longer distances and at higher bandwidths (data rates) than wire cables. Fibers are used instead of metal wires because signals travel along them with less loss and are also immune to electromagnetic interference. This is useful for somewhere like CERN where magnets with their highly powerful magnetic fields could pose a problem.

  5. Characterization of Sisal Fibre Reinforced Concrete | Elinwa ...

    African Journals Online (AJOL)

    Experimental characterization of sisal fibre reinforced concrete showed that incorporating fibre into the concrete mixture is beneficial. Optimum performance for a matrix having sisal fibre as reinforcement is at 3% fibre volume fraction (Vff), with 70mm fibre length (Lf) and at a water-cement ratio of 0.6. There is a load increase ...

  6. Compressive Failure Behaviour of Novel Aramid Fibres

    NARCIS (Netherlands)

    Knijnenberg, A.

    2009-01-01

    Since the development of the first truly synthetic fibres in the late nineteenth century, scientific efforts have lead to large variety of fibres ranging from fibres for textile applications to high performance fibres used as engineering materials. Examples of high performance fibres that are often

  7. Analysis of glass fibre sizing

    DEFF Research Database (Denmark)

    Petersen, Helga Nørgaard; Kusano, Yukihiro; Brøndsted, Povl

    2014-01-01

    Glass fibre reinforced polymer composites are widely used for industrial and engineering applications which include construction, aerospace, automotive and wind energy industry. During the manufacturing glass fibres, they are surface-treated with an aqueous solution. This process and the treated...... surfaces are called sizing. The sizing influences the properties of the interface between fibres and a matrix, and subsequently affects mechanical properties of composites. In this work the sizing of commercially available glass fibres was analysed so as to study the composition and chemical structures....... Soxhlet extraction was used to extract components of the sizing from the glass fibres. The glass fibres, their extracts and coated glass plates were analysed by Thermo-Gravimetric Analysis combined with a mass spectrometer (TGA-MS), and Attenuated Total Reflectance Fourier Transform Infrared (ATR...

  8. An optical fibre interferometric refractometer

    OpenAIRE

    Suhadolnik, Alojz

    2015-01-01

    A new type of optical fibre interferometric refractometer has been made. A double interferometer consists of an optical fibre Mach-Zehnder interferometerand a Michelson interferometer. The first one measures the optical path length difference of the moving sample, while the second one measures the liquid sample displacement in air. A fringe count technique was used on both interferometers in order to obtain the refractive indices of different liquids. The described optical fibre interferometr...

  9. Exhibition: Fibre optics, the future is at hand

    CERN Multimedia

    Anaïs Schaeffer

    2012-01-01

    Until 20 June, the Pont de la Machine in Geneva will host an exhibition on fibre optics, sponsored by SIG. CERN, a major user of this technology, was invited to take part with a presentation of some of its scintillating fibre detectors.   The CERN module, designed for the SIG's fibre optics exhibition. Visitors can discover a cosmic ray detector (on the right) and its oscilloscope (on the left), as well as one of the ALFA detector modules (at the back). The Services industriels genevois (SIG), who are in the process of deploying an optical fibre network in Geneva, have decided to showcase this technology with an exhibition entitled “Fibre optique – Le futur à portée de main.” The exhibition, which will be open to the public from 26 April to 20 June, is being held at the Espace ExpoSIG, at the Pont de la Machine in the centre of Geneva. “CERN’s Physics Department was approached by SIG at the start of this year to ...

  10. Fabrication of Metallic Hollow Nanoparticles

    Science.gov (United States)

    Kim, Jae-Woo (Inventor); Choi, Sr., Sang H. (Inventor); Lillehei, Peter T. (Inventor); Chu, Sang-Hyon (Inventor); Park, Yeonjoon (Inventor); King, Glen C. (Inventor); Elliott, James R. (Inventor)

    2016-01-01

    Metal and semiconductor nanoshells, particularly transition metal nanoshells, are fabricated using dendrimer molecules. Metallic colloids, metallic ions or semiconductors are attached to amine groups on the dendrimer surface in stabilized solution for the surface seeding method and the surface seedless method, respectively. Subsequently, the process is repeated with additional metallic ions or semiconductor, a stabilizer, and NaBH.sub.4 to increase the wall thickness of the metallic or semiconductor lining on the dendrimer surface. Metallic or semiconductor ions are automatically reduced on the metallic or semiconductor nanoparticles causing the formation of hollow metallic or semiconductor nanoparticles. The void size of the formed hollow nanoparticles depends on the dendrimer generation. The thickness of the metallic or semiconductor thin film around the dendrimer depends on the repetition times and the size of initial metallic or semiconductor seeds.

  11. Space Charge Mitigation With Longitudinally Hollow Bunches

    CERN Multimedia

    Oeftiger, Adrian; Rumolo, Giovanni

    2016-01-01

    Hollow longitudinal phase space distributions have a flat profile and hence reduce the impact of transverse space charge. Dipolar parametric excitation with the phase loop feedback systems provides such hollow distributions under reproducible conditions. We present a procedure to create hollow bunches during the acceleration ramp of CERN’s PS Booster machine with minimal changes to the operational cycle. The improvements during the injection plateau of the downstream Proton Synchrotron are assessed in comparison to standard parabolic bunches.

  12. Space charge mitigation with longitudinally hollow bunches

    CERN Document Server

    AUTHOR|(CDS)2088716; Hancock, Steven; Rumolo, Giovanni; CERN. Geneva. ATS Department

    2016-01-01

    Suitably, hollow longitudinal phase space distributions have a flat profile and hence reduce the impact of transverse space charge. Dipolar parametric excitation with the phase loop feedback systems provides such hollow distributions under reproducible conditions. We present a procedure to create hollow bunches during the acceleration ramp of CERN’s PS Booster machine with minimal changes to the operational cycle. The improvements during the injection plateau of the downstream Proton Synchrotron are assessed in comparison to standard parabolic bunches.

  13. Method to fabricate hollow microneedle arrays

    Energy Technology Data Exchange (ETDEWEB)

    Kravitz, Stanley H. (Placitas, NM); Ingersoll, David (Albuquerque, NM); Schmidt, Carrie (Los Lunas, NM); Flemming, Jeb (Albuquerque, NM)

    2006-11-07

    An inexpensive and rapid method for fabricating arrays of hollow microneedles uses a photoetchable glass. Furthermore, the glass hollow microneedle array can be used to form a negative mold for replicating microneedles in biocompatible polymers or metals. These microneedle arrays can be used to extract fluids from plants or animals. Glucose transport through these hollow microneedles arrays has been found to be orders of magnitude more rapid than natural diffusion.

  14. Properties of hemp fibre polymer composites - An optimisation of fibre properties using novel defibration methods and fibre characterisation

    DEFF Research Database (Denmark)

    Thygesen, Anders

    2006-01-01

    Characterization of hemp fibres was carried out with fibres obtained with low handling damage and defibration damage to get an indication of how strong cellulose based fibres that can be produced from hemp. Comparison was made with hemp yarn producedunder traditional conditions where damage...... obtained by steam explosion of hemp fibres prior defibrated with pectin degrading enzymes. The S2 layer in the fibre wall of the hemp fibres consisted of1-4 cellulose rich and lignin poor concentric layers constructed of ca. 100 nm thick lamellae. The microfibril angle showed values in the range 0......-10° for the main part of the S2-layer and 70-90° for the S1-layer. The microfibrils that are mainly parallelwith the fibre axis explain the high fibre stiffness, which in defibrated hemp fibres reached 94 GPa. The defibrated hemp fibres had higher fibre stiffness (88-94 GPa) than hemp yarn (60 GPa), which...

  15. Design of DFB fibre lasers

    DEFF Research Database (Denmark)

    Lauridsen, Vibeke Claudia; Povlsen, Jørn Hedegaard; Varming, Poul

    1998-01-01

    A numerical model for erbium distributed feedback (DFB) fibre lasers is presented. The model is used to optimise the location of a discrete phase-shift to obtain maximum output power. For DFB fibre lasers of up to 10cm in length it is shown that the influence of Kerr nonlinearity with respect...

  16. Flow diagnostics using fibre optics

    Indian Academy of Sciences (India)

    the results of experiments of aerodynamic load measurements at hypersonic speeds. (Mach 8·35 and 7·0) and studies carried out recently in a water tunnel over a lifting hypersonic vehicle with a 2-component fibre-optic strain-gauge balance. Keywords. Fibre optics; flow diagnostics; hypersonic speeds. 1. Introduction.

  17. [Autonomic angiotensinergic fibres in the human heart with an efferent sympathetic cophenotype].

    Science.gov (United States)

    Bohlender, J; Nussberger, J; Tevaearai, H; Imboden, H

    2015-06-01

    The autonomic innervation of the heart consists of sympathetic and parasympathetic nerve fibres, and fibres of the intrinsic ganglionated plexus with noradrenaline and acytylcholine as principal neurotransmitters. The fibres co-release neuropeptides to modulate intracardiac neurotransmission by specific presynaptic and postsynaptic receptors. The coexpression of angiotensin II in sympathetic fibres of the human heart and its role are not known so far. Autopsy specimens of human hearts were studied (n=3; ventricles). Using immunocytological methods, cryostat sections were stained by a murine monoclonal antibody (4B3) directed against angiotensin II and co-stained by polyclonal antibodies against tyrosine hydroxylase, a catecholaminergic marker. Visualisation of the antibodies was by confocal light microscopy or laser scanning microscopy. Angiotensin II-positive autonomic fibres with and without a catecholaminergic cophenotype (hydroxylase-positive) were found in all parts of the human ventricles. In the epicardium, the fibres were grouped in larger bundles of up to 100 and more fibres. They followed the preformed anatomic septa and epicardial vessels towards the myocardium and endocardium where the bundles dissolved and the individual fibres spread between myocytes and within the endocardium. Generally, angiotensinergic fibres showed no synaptic enlargements or only a few if they were also catecholaminergic. The exclusively catechalominergic fibres were characterised by multiple beaded synapses. The autonomic innervation of the human heart contains angiotensinergic fibres with a sympathetic efferent phenotype and exclusively angiotensinergic fibers representing probably afferents. Angiotensinergic neurotransmission may modulate intracardiac sympathetic and parasympathetic activity and thereby influence cardiac and circulatory function. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  18. The effect of dietary fibre on reducing the glycaemic index of bread.

    Science.gov (United States)

    Scazzina, Francesca; Siebenhandl-Ehn, Susanne; Pellegrini, Nicoletta

    2013-04-14

    As bread is the most relevant source of available carbohydrates in the diet and as lowering dietary glycaemic index (GI) is considered favourable to health, many studies have been carried out in order to decrease the GI of bread. The most relevant strategy that has been applied so far is the addition of fibre-rich flours or pure dietary fibre. However, the effectiveness of dietary fibre in bread in reducing the GI is controversial. The purpose of the present review was to discuss critically the effects obtained by adding different kinds of fibre to bread in order to modulate its glycaemic response. The studies were selected because they analysed in vivo whether or not dietary fibre, naturally present or added during bread making, could improve the glucose response. The reviewed literature suggests that the presence of intact structures not accessible to human amylases, as well as a reduced pH that may delay gastric emptying or create a barrier to starch digestion, seems to be more effective than dietary fibre per se in improving glucose metabolism, irrespective of the type of cereal. Moreover, the incorporation of technologically extracted cereal fibre fractions, the addition of fractions from legumes or of specifically developed viscous or non-viscous fibres also constitute effective strategies. However, when fibres or wholemeal is included in bread making to affect the glycaemic response, the manufacturing protocol needs to reconsider several technological parameters in order to obtain high-quality and consumer-acceptable breads.

  19. Reticulation des fibres lignocellulosiques

    Science.gov (United States)

    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.

  20. Hollow fiber dead-end ultrafiltration: Axial transport variations during humic acid filtration

    NARCIS (Netherlands)

    van de Ven, W.J.C.; van 't Sant, K.; Punt, Ineke G.M.; Zwijnenburg, A.; Kemperman, Antonius J.B.; van der Meer, Walterus Gijsbertus Joseph; Wessling, Matthias

    2008-01-01

    This paper describes the dead-end ultrafiltration of humic substances with hollow fiber modules. We show that the resistance of a fouling layer decreases with increasing flux. The lower resistance of the fouling layer is caused by a loss in retention of the membrane for humic acid at these higher

  1. NATURAL FIBRE COMPOSITES: A REVIEW ON FLAX FIBRES

    Directory of Open Access Journals (Sweden)

    YUKSELOGLU S.Muge

    2017-05-01

    Full Text Available In the composite industry, generally glass and carbon fibres are most widely used materials because of their high strength to weight ratio. On the other hand, in recent years, the use of natural fibres as reinforcement in composites have shown some esteem due to their properties such as light weight, low cost, recyclability, biodegradability and an increasing requirement for developing sustainable materials. Some of these natural fibres, such as jute, flax is cost-effective and can be much more in demand due to their specific mechanical properties comparable to the glass fibres. This study focuses on natural fibre composites (NFCs in which polymeric resins are used as matrix materials. NFCs materials have at least one primary component originated from a biological source. Here, fundamentals of NFC materials are presented according to the reinforcement preforms, matrix resins, which are thermosets or thermoplastics, composite manufacturing techniques and characterization. Since NFCs based on renewable resources can provide feasible low-cost structural components and eco-friendly alternatives to conventional structural materials for many applications such as equipment housings, roofing and in large diameter piping. This review is especially carried out in more detail on the flax fibres which are the recently emerged offers for automotive industry. Additionally, fibre/matrix interfaces of these studies are reported.

  2. Hollow system with fin. Transient Green function method combination for two hollow cylinders

    Directory of Open Access Journals (Sweden)

    Buikis Andris

    2017-01-01

    Full Text Available In this paper we develop mathematical model for three dimensional heat equation for the system with hollow wall and fin and construct its analytical solution for two hollow cylindrical sample. The method of solution is based on Green function method for one hollow cylinder. On the conjugation conditions between both hollow cylinders we construct solution for system wall with fin. As result we come to integral equation on the surface between both hollow cylinders. Solution is obtained in the form of second kind Fredholm integral equation. The generalizing of Green function method allows us to use Green function method for regular non-canonical domains.

  3. Hollow nanocrystals and method of making

    Science.gov (United States)

    Alivisatos, A Paul [Oakland, CA; Yin, Yadong [Moreno Valley, CA; Erdonmez, Can Kerem [Berkeley, CA

    2011-07-05

    Described herein are hollow nanocrystals having various shapes that can be produced by a simple chemical process. The hollow nanocrystals described herein may have a shell as thin as 0.5 nm and outside diameters that can be controlled by the process of making.

  4. Helically twisted photonic crystal fibres

    Science.gov (United States)

    Russell, P. St. J.; Beravat, R.; Wong, G. K. L.

    2017-02-01

    Recent theoretical and experimental work on helically twisted photonic crystal fibres (PCFs) is reviewed. Helical Bloch theory is introduced, including a new formalism based on the tight-binding approximation. It is used to explore and explain a variety of unusual effects that appear in a range of different twisted PCFs, including fibres with a single core and fibres with N cores arranged in a ring around the fibre axis. We discuss a new kind of birefringence that causes the propagation constants of left- and right-spinning optical vortices to be non-degenerate for the same order of orbital angular momentum (OAM). Topological effects, arising from the twisted periodic `space', cause light to spiral around the fibre axis, with fascinating consequences, including the appearance of dips in the transmission spectrum and low loss guidance in coreless PCF. Discussing twisted fibres with a single off-axis core, we report that optical activity in a PCF is opposite in sign to that seen in a step-index fibre. Fabrication techniques are briefly described and emerging applications reviewed. The analytical results of helical Bloch theory are verified by an extensive series of `numerical experiments' based on finite-element solutions of Maxwell's equations in a helicoidal frame. This article is part of the themed issue 'Optical orbital angular momentum'.

  5. Helically twisted photonic crystal fibres.

    Science.gov (United States)

    Russell, P St J; Beravat, R; Wong, G K L

    2017-02-28

    Recent theoretical and experimental work on helically twisted photonic crystal fibres (PCFs) is reviewed. Helical Bloch theory is introduced, including a new formalism based on the tight-binding approximation. It is used to explore and explain a variety of unusual effects that appear in a range of different twisted PCFs, including fibres with a single core and fibres with N cores arranged in a ring around the fibre axis. We discuss a new kind of birefringence that causes the propagation constants of left- and right-spinning optical vortices to be non-degenerate for the same order of orbital angular momentum (OAM). Topological effects, arising from the twisted periodic 'space', cause light to spiral around the fibre axis, with fascinating consequences, including the appearance of dips in the transmission spectrum and low loss guidance in coreless PCF. Discussing twisted fibres with a single off-axis core, we report that optical activity in a PCF is opposite in sign to that seen in a step-index fibre. Fabrication techniques are briefly described and emerging applications reviewed. The analytical results of helical Bloch theory are verified by an extensive series of 'numerical experiments' based on finite-element solutions of Maxwell's equations in a helicoidal frame.This article is part of the themed issue 'Optical orbital angular momentum'. © 2017 The Authors.

  6. Dispersion properties of photonic crystal fibres

    DEFF Research Database (Denmark)

    Bjarklev, Anders Overgaard; Broeng, Jes; Dridi, Kim

    1998-01-01

    Approximate dispersion and bending properties of all-silica two-dimensional photonic crystal fibres are characterised by the combination of an effective-index model and classical analysis tools for optical fibres. We believe for the first time to have predicted the dispersion properties of photonic...... crystal fibres. The results strongly indicate that these fibres have potential applications as dispersion managing components...

  7. Optical fibre sensing during critical care

    Science.gov (United States)

    Hernandez, F. U.; Wang, T.; Korposh, S.; Correia, R.; Hayes-Gill, B. R.; Hromadka, J.; Mohd Hazlan, N. N.; Norris, A.; Evans, D.; Lee, S.-W.; Morgan, S. P.

    2017-04-01

    Optical fibre sensing is a platform technology for applications in biomedical and environmental monitoring. Fibre Bragg Gratings can be used to monitor parameters such as pressure and temperature. Alternatively, coating the fibres with functional layers, either at the tip of the fibre, on a U-shaped fibre, or a long period grating enables sensing of analytes in liquids and gases. This paper describes the application of optical fibre sensing techniques during mechanical ventilation via an endotracheal tube in critical care. Functional coatings on the fibres are used to monitor humidity of inspired air and can be used to monitor other analytes.

  8. Optical fibre gas detections systems

    Science.gov (United States)

    Culshaw, Brian

    2016-05-01

    This tutorial review covers the principles of and prospects for fibre optic sensor technology in gas detection. Many of the potential benefits common to fibre sensor technology also apply in the context of gas sensing - notably long distance - many km - access to multiple remote measurement points; invariably intrinsic safety; access to numerous important gas species and often uniquely high levels of selectivity and/or sensitivity. Furthermore, the range of fibre sensor network architectures - single point, multiple point and distributed - enable unprecedented flexibility in system implementation. Additionally, competitive technologies and regulatory issues contribute to final application potential.

  9. Aligned flax fibre/polylactate composites

    DEFF Research Database (Denmark)

    Madsen, Bo; Lilholt, Hans; Thygesen, Anders

    2008-01-01

    The potential of biocomposites in engineering applications is demonstrated by using aligned flax fibre/polylactate composites as a materials model system. The failure stress of flax fibres is measured by tensile testing of single fibres and fibre bundles. For both fibre configurations, it is found...... that failure stress is decreased by increasing the tested fibre volume. Based on two types of flax fibre preforms: carded sliver and unidirectional non-crimp fabric, aligned flax fibre/polylactate composites were fabricated with variable fibre content. The volumetric composition and tensile properties...... of the composite were measured. For composites with a fibre content of 37 % by volume, stiffness is about 20 GPa and failure stress is about 180 MPa. The tensile properties of the composites are analysed with a modified rule of mixtures model, which includes the effect of porosity. The experimental results...

  10. Ultrafast Mid-IR Nonlinear Optics in Gas-filled Hollow-core Photonic Crystal Fibers

    DEFF Research Database (Denmark)

    Habib, Selim

    action of self-focusing self-phase modulation (SPM) and anomalous GVD allows strong soliton self-compression down to sub-single cycle duration inside HC-AR fiber. The peak intensity at the maximum temporal compression can reach over 1014 W/cm2 which is sufficient to ionize the gas and form a plasma. We......Invention of hollow-core fiber has been proven an ideal medium to study light-gas interaction. Tight confinement of light inside hollowcore fiber allows unremitting and tailored interaction between light and gas over long distances. In this work, we used a special kind of hollowcore fiber − hollow...

  11. An optical fibre interferometric refractometer

    Science.gov (United States)

    Suhadolnik, A.

    2007-05-01

    A new type of optical fibre interferometric refractometer has been made. A double interferometer consists of an optical fibre Mach-Zehnder interferometer and a Michelson interferometer. The first one measures the optical path length difference of the moving sample, while the second one measures the liquid sample displacement in air. A fringe count technique was used on both interferometers in order to obtain the refractive indices of different liquids. The described optical fibre interferometric refractometer was tested by measuring the refractive indices of different liquids, and the achieved results were compared to the results found in the literature. In addition, the refractive index of different concentrations of NaCl in water was measured and compared with the calculated calibration curve. The advantage of the proposed refractometer is high accuracy measurements including the simple construction of the optical fibre Mach-Zehnder interferometer and the commercially available Michelson interferometer.

  12. Modeling of photonic Crystal Fibres

    DEFF Research Database (Denmark)

    Bjarklev, Anders Overgaard; Broeng, Jes; Barkou, Stig Eigil

    1999-01-01

    Diferent theoretical models for analysis of photonic crystal fibres are reviewed and compaired. The methods span from simple scalar approaches to full-vectorial models using different mode-field decompositions. The specific advantages of the methods are evaluated.......Diferent theoretical models for analysis of photonic crystal fibres are reviewed and compaired. The methods span from simple scalar approaches to full-vectorial models using different mode-field decompositions. The specific advantages of the methods are evaluated....

  13. Current status of natural fibres

    CSIR Research Space (South Africa)

    Anandjiwala, RD

    2006-12-01

    Full Text Available for both existing and new high- value added markets in textiles, such as composites, paper/pulp, and industrial/nutritional oils [1-3]. The possibilities of using all the components of the fibre crop provide wide ranging opportunities both, in up... [35]. Nonwoven Beyond apparel markets there are opportunities in nonwoven materials and technical textiles. With the increasing awareness in environmental conservation, the use of natural fibres in disposable nonwovens is increasing...

  14. Dynamics and instabilities in long SRS fibre lasers with linear and ring cavities

    Science.gov (United States)

    Mel’nikov, L. A.; Mazhirina, Yu. A.

    2017-12-01

    We report results of numerical simulation of the nonlinear dynamics of SRS fibre lasers with linear and ring cavity configurations and of the specific features of manifestation of instabilities of steady-state lasing in fibres with length-periodic modulation of dispersion. The simulation is performed within the approach based on solving transport equations. The dynamics of the SRS laser with linear configuration is found to depend strongly on the coupling of counterpropagating waves at the fibre end faces and radically changes in the presence of reflections at the left or right end faces under asymmetric pumping. The existence of signal beatings in the absence of nonreciprocity (rotation) of the cavity and the presence of coupling between counterpropagating waves is demonstrated for the ring laser. A specific feature of instabilities of the propagation regime of a constant-intensity signal in a fibre with a group-velocity dispersion periodically modulated over length is their occurrence at an arbitrary dispersion sign.

  15. Hollow Micro-/Nanostructures: Synthesis and Applications

    KAUST Repository

    Lou, Xiong Wen (David)

    2008-11-03

    Hollow micro-nanostructures are of great interest in many current and emerging areas of technology. Perhaps the best-known example of the former is the use of fly-ash hollow particles generated from coal power plants as partial replacement for Portland cement, to produce concrete with enhanced strength and durability. This review is devoted to the progress made in the last decade in synthesis and applications of hollow micro-nanostructures. We present a comprehensive overview of synthetic strategies for hollow structures. These strategies are broadly categorized into four themes, which include well-established approaches, such as conventional hard-templating and soft-templating methods, as well as newly emerging methods based on sacrificial templating and template-free synthesis. Success in each has inspired multiple variations that continue to drive the rapid evolution of the field. The Review therefore focuses on the fundamentals of each process, pointing out advantages and disadvantages where appropriate. Strategies for generating more complex hollow structures, such as rattle-type and nonspherical hollow structures, are also discussed. Applications of hollow structures in lithium batteries, catalysis and sensing, and biomedical applications are reviewed. © 2008 WILEY-VCH Verlag GmbH & Co. KGaA,.

  16. Preparation and evaluation of glyceryl monooleate-coated hollow-bioadhesive microspheres for gastroretentive drug delivery.

    Science.gov (United States)

    Liu, Yuanfen; Zhang, Jianjun; Gao, Yuan; Zhu, Jiabi

    2011-07-15

    The purpose of this study was to produce hollow and bioadhesive microspheres to lengthen drug retention time in the stomach. In these microspheres, ethylcellulose was used as the matrix, Eudragit EPO was employed to modulate the release rate, and glyceryl monooleate (GMO) was the bioadhesive polymer in situ. The morphological characteristics of the microspheres were defined using scanning electron microscopy. The in vitro release test showed that the release rate of drug from the microspheres was pH-dependent, and was not influenced by the GMO coating film. The prepared microspheres demonstrated strong mucoadhesive properties with good buoyancy both in vitro and in vivo. Pharmacokinetic analysis indicated that the elimination half-life time of the hollow-bioadhesive microspheres was prolonged, and that the elimination rate was decreased. In conclusion, the hollow-bioadhesive synergic drug delivery system may be advantageous in the treatment of stomach diseases. Copyright © 2011 Elsevier B.V. All rights reserved.

  17. Hollow Waveguide Gas Sensor for Mid-Infrared Trace Gas Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Kim, S; Young, C; Chan, J; Carter, C; Mizaikoff, B

    2007-07-12

    A hollow waveguide mid-infrared gas sensor operating from 1000 cm{sup -1} to 4000 cm{sup -1} has been developed, optimized, and its performance characterized by combining a FT-IR spectrometer with Ag/Ag-halide hollow core optical fibers. The hollow core waveguide simultaneously serves as a light guide and miniature gas cell. CH{sub 4} was used as test analyte during exponential dilution experiments for accurate determination of the achievable limit of detection (LOD). It is shown that the optimized integration of an optical gas sensor module with FT-IR spectroscopy provides trace sensitivity at the few hundreds of parts-per-billion concentration range (ppb, v/v) for CH{sub 4}.

  18. Connectorization of fibre Bragg grating sensors recorded in microstructured polymer optical fibre

    DEFF Research Database (Denmark)

    Abang, A.; Saez-Rodriguez, D.; Nielsen, Kristian

    2013-01-01

    We describe te production and characterization of FC/PC connectorised fibre Bragg grating sensors in polymer fibre. Sensors were recorded in few-moded and single mode microstructured fibre composed of poly (methyl methacrylate).......We describe te production and characterization of FC/PC connectorised fibre Bragg grating sensors in polymer fibre. Sensors were recorded in few-moded and single mode microstructured fibre composed of poly (methyl methacrylate)....

  19. The Chemical Composition of Grape Fibre

    Directory of Open Access Journals (Sweden)

    Jolana Karovičová

    2015-05-01

    Full Text Available Dietary fibres from cereals are much more used than dietary fibres from fruits; however, dietary fibres from fruits have better quality. In recent years, for economic and environmental reasons, there has been a growing pressure to recover and exploit food wastes. Grape fibre is used to fortify baked goods, because the fibre can lower blood sugar, cut cholesterol and may even prevent colon cancer. Grape pomace is a functional ingredient in bakery goods to increase total phenolic content and dietary fibre in nourishment. The aim of this study was to determine the chemical composition of commercial fibres, obtained from different Grape sources concerning their chemical properties such as moisture, ash, fat, protein, total dietary fibre. The chemical composition of Grape fibre is known to vary depending on the Grape cultivar, growth climates, and processing conditions. The obliged characteristics of the fibre product are: total dietary fibre content above 50%, moisture lower than 9%, low content of lipids, a low energy value and neutral flavour and taste. Grape pomace represents a rich source of various high-value products such as ethanol, tartrates and malates, citric acid, Grape seed oil, hydrocolloids and dietary fibre. Used commercial Grape fibres have as a main characteristic, the high content of total dietary fibre. Amount of total dietary fibre depends on the variety of Grapes. Total dietary fibre content (TDF in our samples of Grape fibre varied from 56.8% to 83.6%. There were also determined low contents of moisture (below 9%. In the samples of Grape fibre were determined higher amount of protein (8.6 - 10.8%, mineral (1.3 - 3.8% and fat (2.8 - 8.6%. This fact opens the possibility of using both initial by-products as ingredients in the food industry, due to the effects associated with the high total dietary fibre content.

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

    Science.gov (United States)

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

    2016-02-22

    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

    Science.gov (United States)

    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.

  2. Ultra-High Speed Switching Functionalities using none-linear fibres

    DEFF Research Database (Denmark)

    Galili, Michael

    2007-01-01

    This thesis deals with optical signal processing of high-speed optical data signals at 160-640 Gbit/s. By exploiting non-linear effects in optical fibres several signal processing functionalities are implemented. This includes wavelength conversion of intensity modulated and phase modulated data...

  3. Hollow Core, Whispering Gallery Resonator Sensors

    CERN Document Server

    Ward, Jonathan M; Chormaic, Síle Nic

    2014-01-01

    A review of hollow core whispering gallery resonators (WGRs)is given. After a short introduction to the topic of whispering gallery resonators we provide a description of whispering gallery modes in hollow or liquid core WGRs. Next, whispering gallery mode (WGM) sensing mechanisms are outlined and some fabrication methods for microbubbles, microcapillaries and other tubular WGM devices are discussed. We then focus on the most common applications of hollow core WGRs, namely refractive index and temperature sensing, gas sensing, force sensing, biosensing, and lasing. The review highlights some of the key papers in this field and gives the reader a general overview of the current state-of-the-art.

  4. Characteristics of SBS dynamics in single-mode optical fibres

    Energy Technology Data Exchange (ETDEWEB)

    Gordeev, A A; Efimkov, V F; Zubarev, I G; Mikhailov, S I; Sobolev, V B [P N Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

    2016-03-31

    The characteristics of the gain of Stokes pulses in single-mode optical fibres by stimulated Brillouin scattering (SBS) of monochromatic and nonmonochromatic pump signals have been investigated by numerical simulation using a spectral approach. Conditions under which 'slow light' (caused by a group delay) can be implemented are found (it is reasonable to apply this term to a process in which a pulse is delayed with conservation of its shape). The plane-wave interaction model is shown to describe adequately the dynamics of this process in single-mode fibres. A number of gain modes are investigated for Stokes pulses with different time structures upon monochromatic and nonmonochromatic excitation. A new data transfer technique is proposed, which is based on the conversion of stepwise phase modulation of the input Stokes signal into amplitude modulation of the output signal. (nonlinear optical phenomena)

  5. [Comparative study on four membrane modules in membrane filtration process of Huanglian Jiedu decoction].

    Science.gov (United States)

    Liu, Hong-Bo; Li, Bo; Guo, Li-Wei; Xiao, Wei

    2013-02-01

    To compare the membrane filtration process of four membrane modules namely, FMX rotating disk flat membrane module, hollow fiber membrane module, tubular membrane module and filter cup membrane module, with traditional Chinese medicine compound Huanglian Jiedu decoction as the experimental subject. Under the same experimental operating conditions, the four membrane modules in membrane filtration process of Huanglian Jiedu decoction were compared in terms flux, resistance distribution, transmittance of index components and membrane fouling. Three membrane modules in the dynamic filtration form--FMX rotating disk flat membrane module, hollow fiber membrane module and tubular membrane module had more advantages than filter cup membrane module in the static dead-end filtration form in terms of permeate flux, transmittance of index components and membrane fouling. However, FMX membrane module that made the fluid in a strong vortex status had better performance than hollow fiber membrane and tubular membrane module in permeate flux and membrane fouling.

  6. Interference Cancellation for Hollow-Core Fiber Reference Cells

    DEFF Research Database (Denmark)

    Seppä, Jeremias; Merimaa, Mikko; Merimaa, Mikko

    2015-01-01

    Doppler-free saturated absorption spectroscopy of gases in hollow-core fiber (HCF)-based cells can be used for realizing new compact, robust, and portable frequency standards. In this paper, methods for cancelling interferences resulting from the optical connections between standard fiber and HCF...... and other factors such as varying coupling to HCF modes are investigated. Laser power modulation with simultaneous detection of ac and dc signal is used to separate saturated absorption from interferences. In addition, a technique of two piezoelectric stack actuators stretching the fiber at different...... locations is described. The presented experimental results demonstrate that 99% interference attenuation is readily attainable with the techniques. Frequency comb-referenced measurement of saturated acetylene absorption features near 1.54 μm, with fiber length and power modulation, is presented...

  7. Practical Hydrogen Loading of Air Silica Fibres

    DEFF Research Database (Denmark)

    Sørensen, Henrik Rokkjær; Jensen, Jesper Bevensee; Jensen, Jesper Bo Damm

    2005-01-01

    A method for hydrogen-loading air-silica optical fibres has been developed allowing out-diffusion times comparable to standard step-index fibres. Examples of the first grating written in Ge-doped air-silica fibres using a 266nm UV-laser are shown.......A method for hydrogen-loading air-silica optical fibres has been developed allowing out-diffusion times comparable to standard step-index fibres. Examples of the first grating written in Ge-doped air-silica fibres using a 266nm UV-laser are shown....

  8. Carbon nanotubes for ultrafast fibre lasers

    Directory of Open Access Journals (Sweden)

    Chernysheva Maria

    2016-06-01

    Full Text Available Carbon nanotubes (CNTs possess both remarkable optical properties and high potential for integration in various photonic devices. We overview, here, recent progress in CNT applications in fibre optics putting particular emphasis on fibre lasers. We discuss fabrication and characterisation of different CNTs, development of CNT-based saturable absorbers (CNT-SA, their integration and operation in fibre laser cavities putting emphasis on state-of-the-art fibre lasers, mode locked using CNT-SA. We discuss new design concepts of high-performance ultrafast operation fibre lasers covering ytterbium (Yb, bismuth (Bi, erbium (Er, thulium (Tm and holmium (Ho-doped fibre lasers.

  9. Retrofitting of bridge hollow piers with CFRP

    OpenAIRE

    Pedro Delgado; Patrício Rocha; João Pedrosa; António Arêde; Nelson Vila Pouca; Miguel Santos; Aníbal Costa; Raimundo Delgado

    2007-01-01

    Hollow bridge piers generally have large section dimensions, with reinforcement barsspread along both wall faces. Unlike common solid section columns, quite often the shear effect hasgreat importance on the pier behavior. Therefore, it is of particular relevance that special attention isgiven to this issue when the assessment and retrofit of RC hollow section piers is envisaged. Representativeof typical bridge construction, RC piers were tested at LESE ¿ the Laboratory of Earthquakeand Struct...

  10. The Influence of Fibre Content on the Performance of Steel Fibre ...

    African Journals Online (AJOL)

    Steel fibres are commonly used in the refractory industry to reinforce high temperature concretes. Little information is available on the effect of fibre content on refractory performance and in particular resistance to thermal shock. This study has examined the influence of fibre content of stainless steel melt extract fibres on the ...

  11. Fibre reinforced concrete in flexure and single fibre pull-out test: a correlation

    Science.gov (United States)

    Manca, M.; Ciancio, D.; Dight, P.

    2017-09-01

    The aim of the present work is to assess whether a single fibre pull-out test can be related to the behaviour of multiple fibres in fibre reinforced concrete under bending condition. A simple model based on the stress block theory is described and compared with experimental results on three point bending tests with aligned fibres.

  12. Production and cross-sectional characterization of aligned co-electrospun hollow microfibrous bulk assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Feng-Lei [Centre for Imaging Sciences, The University of Manchester, Manchester M13 9PT (United Kingdom); The School of Materials, The University of Manchester, Manchester M13 9PL (United Kingdom); CRUK-EPSRC Cancer Imaging Centre in Cambridge and Manchester (United Kingdom); Parker, Geoff J.M., E-mail: geoff.parker@manchester.ac.uk [Centre for Imaging Sciences, The University of Manchester, Manchester M13 9PT (United Kingdom); CRUK-EPSRC Cancer Imaging Centre in Cambridge and Manchester (United Kingdom); Eichhorn, Stephen J. [College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter EX4 4QF (United Kingdom); Hubbard Cristinacce, Penny L. [Centre for Imaging Sciences, The University of Manchester, Manchester M13 9PT (United Kingdom); School of Psychological Sciences, University of Manchester, Manchester M13 9PT (United Kingdom)

    2015-11-15

    The development of co-electrospun (co-ES) hollow microfibrous assemblies of an appreciable thickness is critical for many practical applications, including filtration membranes and tissue-mimicking scaffolds. In this study, thick uniaxially aligned hollow microfibrous assemblies forming fiber bundles and strips were prepared by co-ES of polycaprolactone (PCL) and polyethylene oxide (PEO) as shell and core materials, respectively. Hollow microfiber bundles were deposited on a fixed rotating disc, which resulted in non-controllable cross-sectional shapes on a macroscopic scale. In comparison, fiber strips were produced with tuneable thickness and width by additionally employing an x–y translation stage in co-ES. Scanning electron microscopy (SEM) images of cross-sections of fiber assemblies were analyzed to investigate the effects of production time (from 0.5 h to 12 h), core flow rate (from 0.8 mL/h to 2.0 mL/h) and/or translation speed (from 0.2 mm/s to 5 mm/s) on the pores and porosity. We observed significant changes in pore size and shape with core flow rate but the influence of production time varied; five strips produced under the same conditions had reasonably good size and porosity reproducibility; pore sizes didn't vary significantly from strip bottom to surface, although the porosity gradually decreased and then returned to the initial level. - Highlights: • Hollow microfibrous assemblies based on co-electrospinning are demonstrated. • The thickness and width of co-electrospun strips were controllable. • Cross-sections of fibres had non-normally distributed pore sizes and shapes. • Cross-sections were significantly influenced by production time and flow rate. • Co-electrospun strips had reasonably good reproducible cross-sections.

  13. Supercontinuum generation in photonic crystal fibres with core filled with toluene

    Science.gov (United States)

    Van, Lanh Chu; Anuszkiewicz, Alicja; Ramaniuk, Aliaksandr; Kasztelanic, Rafal; Dinh Xuan, Khoa; Cao Long, Van; Trippenbach, Marek; Buczyński, Ryszard

    2017-12-01

    A photonic crystal fibre with hollow core filled with toluene is considered as a new system for coherent supercontinuum generation. The dispersion characteristics are studied for various geometrical parameters of photonic crystal fibres. Two structures with lattice constant 2 μm, filling factors d/Λ 0.3 and 0.35 and toluene core of diameters of 3.34 and 3.23 μm have flat dispersion in the near infrared range. The structure with d/Λ = 0.3 has all-normal dispersion characteristics in whole near-infrared wavelength range, while the second structure (d/Λ = 0.35) has anomalous dispersion for wavelengths longer than 1.5 μm. Although confinement losses in the considered structures are as high as 0.4 dB cm‑1, we show that the generation of coherent supercontinuum in the range 1.0–1.7 μm with the pulse energy conversion of 16% is feasible in 4 cm long fibre samples with standard fibre femtosecond lasers.

  14. Etude D'une liaison Radio sur fibre

    OpenAIRE

    Hamedi, Yasmine-Djazia

    2014-01-01

    Notre mémoire est divisé en trois chapitres. Dans le premier chapitre, nous allons décrire différents composants qui entrent dans le cadre de la réalisation des liaisons de transmission par fibre optique et un rappel sur les différents types de sources optiques, le principe de quelques formats de modulation ainsi que les principaux éléments constituants le module de réception, l’origine des principales dégradations subies par le signal au cours de sa transmission. Le second chapitre, nous ...

  15. Fresnel-Reflection-Free Self-Aligning Nanospike Interface between a Step-Index Fiber and a Hollow-Core Photonic-Crystal-Fiber Gas Cell

    Science.gov (United States)

    Pennetta, Riccardo; Xie, Shangran; Lenahan, Frances; Mridha, Manoj; Novoa, David; Russell, Philip St. J.

    2017-07-01

    We report a fully integrated interface delivering efficient, reflection-free, single-mode, and self-aligned coupling between a step-index fiber and a gas-filled hollow-core photonic crystal fiber. The device offers a universal solution for interfacing solid and hollow cores and can be sealed to allow operation either evacuated or at high pressure. Stimulated Raman scattering and molecular modulation of light are demonstrated in a H2 -filled hollow-core photonic crystal fiber using the device.

  16. Durability of cracked fibre reinforced concrete structures

    DEFF Research Database (Denmark)

    Hansen, Ernst Jan De Place; Nielsen, Laila

    1997-01-01

    (capillary water uptake) is used, involving an in-situ method and a laboratory method. Three different concrete qualities as well as steel fibres (ZP) and polypropylene fibres (PP) are used. Results of the durability tests on cracked FRC-beams are compared to results for uncracked FRC-beams and beams without...... fibres and the influence of fibres and cracks on the water uptake is discussed....

  17. Photonic crystal fibres and effective index approaches

    DEFF Research Database (Denmark)

    Riishede, Jesper; Libori, Stig E. Barkou; Bjarklev, Anders Overgaard

    2001-01-01

    Photonic crystal fibres are investigated with an effective index approach. The effective index of both core and cladding is found to be wavelength dependent. Accurate modelling must respect the rich topology of these fibres.......Photonic crystal fibres are investigated with an effective index approach. The effective index of both core and cladding is found to be wavelength dependent. Accurate modelling must respect the rich topology of these fibres....

  18. Wavelength Conversion by using Multiple Fibres

    DEFF Research Database (Denmark)

    Fenger, Christian; Iversen, Villy Bæk

    2002-01-01

    We explain how wavelength conversion can be achieved by using multiple fibres, and show that multiple fibres reduce blocking probability in dynamic all-optical networks, whereby the need for conversion in all-optical networks will be limited......We explain how wavelength conversion can be achieved by using multiple fibres, and show that multiple fibres reduce blocking probability in dynamic all-optical networks, whereby the need for conversion in all-optical networks will be limited...

  19. Local fibred right adjoints are polynomial

    DEFF Research Database (Denmark)

    Kock, Anders; Kock, Joachim

    2013-01-01

    For any locally cartesian closed category E, we prove that a local fibred right adjoint between slices of E is given by a polynomial. The slices in question are taken in a well known fibred sense......For any locally cartesian closed category E, we prove that a local fibred right adjoint between slices of E is given by a polynomial. The slices in question are taken in a well known fibred sense...

  20. Super-tough carbon-nanotube fibres

    Science.gov (United States)

    Dalton, Alan B.; Collins, Steve; Muñoz, Edgar; Razal, Joselito M.; Ebron, Von Howard; Ferraris, John P.; Coleman, Jonathan N.; Kim, Bog G.; Baughman, Ray H.

    2003-06-01

    The energy needed to rupture a fibre (its toughness) is five times higher for spider silk than for the same mass of steel wire, which has inspired efforts to produce spider silk commercially. Here we spin 100-metre-long carbon-nanotube composite fibres that are tougher than any natural or synthetic organic fibre described so far, and use these to make fibre supercapacitors that are suitable for weaving into textiles.

  1. Perturbed solitons in birefringent fibres

    CERN Document Server

    Horikis, T P

    2003-01-01

    A perturbation theory based on inverse scattering theory is developed for the coupled nonlinear Schroedinger equations. The theory finds useful application to the study of pulse propagation down a birefringent optical fibre and is used to examine features of the radiation field shed by a soliton pulse propagating down the fibre. The radiation field is linked to the scattering data through a transform pair which in the linear limit reduces to the forward and inverse Fourier transform pair. A complementary approach, which is in total agreement to these results, is also discussed.

  2. Human Dietary Fibre: A Review,

    Science.gov (United States)

    1979-05-01

    167. Emivironmuental factors and cancer of the co loui and breast . Bastw(iod, \\l . .-\\ . and 1). Hanuiltomi (1968). Biochemii. Biop hvs. Acta 152...Disease 9 Dietary Fibre aiicl Colonic Cancer 10 Fibre and Appendicitis II 1 i1)re and Dental Caries 11 References 1)istr ibution List __________ Access...iti i lxl rtamit effects of fil ) re on solute and bacterial act iv i ty , ~v liich influeiice tile fate (if bacterialmet abo l i t e s of so lt ites

  3. Mohair, cashmere and other animal hair fibres

    CSIR Research Space (South Africa)

    Hunter, L

    2012-11-01

    Full Text Available animal hair fibres L Hunter, CSIR and Nelson Mandela Metropolitan University (NMMU), South Africa Although luxury animal fibres, excluding silk, represent far less than 0.1% of global fibre production, they play a very significant role in the luxury...

  4. Ultrafast Nonlinear Fibre Optics and Supercontinuum Generation

    Science.gov (United States)

    Dudley, John M.; Cherif, Rim; Coen, Stephane; Genty, Goery

    This chapter presents a concise overview of nonlinear fibre optics, focusing particularly on the physics of supercontinuum generation in optical fibre for different regimes of pulse duration and for propagation in dispersion varying fibre. Soliton dynamics and their influence are emphasized, and basic numerical code is provided allowing higher-order soliton effects to be studied within a nonlinear Schrodinger equation model.

  5. Mechanical processing of bast fibres: The occurrence of damage and its effect on fibre structure

    DEFF Research Database (Denmark)

    Hänninen, Tuomas; Thygesen, Anders; Mehmood, Shahid

    2012-01-01

    Currently, separation processes used for natural fibres for composite reinforcing textiles cause a significant amount of damage to the fibres. Microscopic analysis showed that industrially processed flax (Linum usitassimium L.) fibres contained significantly more defects than green or retted ones...... to heterogeneous reactivity. Analogous findings were observed in hemp (Cannabis sativa L.) fibre damaged in the laboratory under controlled conditions, emphasising the need to develop extraction and separation processes that minimise mechanical damage to the fibres....

  6. Multilayer Graphene for Waveguide Terahertz Modulator

    DEFF Research Database (Denmark)

    Khromova, I.; Andryieuski, Andrei; Lavrinenko, Andrei

    2014-01-01

    We study terahertz to infrared electromagnetic properties of multilayer graphene/dielectric artificial medium and present a novel concept of terahertz modulation at midinfrared wavelengths. This approach allows the realization of high-speed electrically controllable terahertz modulators based...... on hollow waveguide sections filled with multilayer graphene....

  7. Thermal wave interferometry of gas-liquid using optical fibre thermal wave resonator cavity technique

    Energy Technology Data Exchange (ETDEWEB)

    Azmi, B Z; Noroozi, M; Sulaiman, Z A; Wahab, Z A; Moksin, M M, E-mail: azmizak@gmail.co [Physics Department, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia)

    2010-03-01

    The optical fibre thermal wave resonator cavity (OF-TWRC) technique was used to measure thermal diffusivity of a two-layer sample; air-liquid. The thermal waves were generated by transmitting the modulated laser beam through one end of optical fibre and illuminating the other fibre end surface that metalised with silver paint. The cavity length scan was done by moving the fibre end surface towards the pyroelectric detector continuously through air and then into the liquid. A good linear relationship of pyroelectric amplitude with respect to cavity length was obtained in thermally thick region in both media; air and liquid. The thermal diffusivity of air, glycerol and water obtained were closed to the literature values.

  8. Nonlinear microstructured polymer optical fibres

    DEFF Research Database (Denmark)

    Frosz, Michael Henoch

    is potentially the case for microstructured polymer optical fibres (mPOFs). Another advantage is that polymer materials have a higher biocompatibility than silica, meaning that it is easier to bond certain types of biosensor materials to a polymer surface than to silica. As with silica PCFs, it is difficult...

  9. Cool application for Optical Fibres

    CERN Multimedia

    2001-01-01

    In a new first for CERN, optical fibres have been put on test to measure very low temperatures. If these tests prove successful, this new technology could lead to important cost-saving changes in the way the temperatures of superconducting magnets are measured. There was excitement in the air last March when the team led by Walter Scandale and Luc Thévenaz tested very low temperature measurement using optical fibres. This spring in CERN's Cryogenics lab an idea was put to the test as a new kind of low-temperature thermometry using optical fibres was tested down to 2 Kelvin (around 300 degrees below room temperature), and the first results are looking good. Optical fibres are well known for their ability to carry large amounts of data around the world, but it is less well known that they can be used for measuring temperatures. The intuition that they might be able to measure very low temperatures - such as those of the LHC magnets - came to the attention of CERN's Walter Scandale at the Optical Fi...

  10. Moisture sorption in naturally coloured cotton fibres

    Science.gov (United States)

    Ceylan, Ö.; De Clerck, K.

    2017-10-01

    Increasing environmental concerns have stimulated an interest in naturally coloured cottons. As many commercial and technical performance aspects of cotton fibres are influenced by their response towards atmospheric humidity, an in-depth research on moisture sorption behaviour of these fibres using dynamic vapour sorption is carried out. Significant differences were observed in sorption capacity and hysteresis behaviour of brown and green cotton fibres. These differences are mainly attributed to the variations in maturity and crystallinity index of the fibres. This study provides valuable insights into the moisture sorption behaviour of naturally coloured cotton fibres.

  11. Method for the production of fabricated hollow microspheroids

    Energy Technology Data Exchange (ETDEWEB)

    Wickramanayake, Shan; Luebke, David R.

    2015-06-09

    The method relates to the fabrication of a polymer microspheres comprised of an asymmetric layer surrounding a hollow interior. The fabricated hollow microsphere is generated from a nascent hollow microsphere comprised of an inner core of core fluid surrounded by a dope layer of polymer dope, where the thickness of the dope layer is at least 10% and less than 50% of the diameter of the inner core. The nascent hollow microsphere is exposed to a gaseous environment, generating a vitrified hollow microsphere, which is subsequently immersed in a coagulation bath. Solvent exchange produces a fabricated hollow microsphere comprised of a densified outer skin surrounding a macroporous inner layer, which surrounds a hollow interior. In an embodiment, the polymer is a polyimide or a polyamide-imide, and the non-solvent in the core fluid and the coagulation bath is water. The fabricated hollow microspheres are particularly suited as solvent supports for gas separation processes.

  12. EDITORIAL: The 20th International Conference on Optical Fibre Sensors, OFS-20 The 20th International Conference on Optical Fibre Sensors, OFS-20

    Science.gov (United States)

    Culshaw, Brian; Ecke, Wolfgang; Jones, Julian; Tatam, Ralph; Willsch, Reinhardt

    2010-09-01

    Welcome to our special issue on fibre optic sensors. Fibre optic sensors were first suggested in the patent literature in the mid 1960s as an innovative means for making measurements. This proposed a surface finish measurement tool with high precision and resulted in an instrument that remains available today. Much has happened since, with significant innovation in the techniques through which light propagating whilst guided in a fibre can be unambiguously, repeatedly and predictably modulated in response to an external phenomenon. The technique offers not only the precision mentioned earlier but also inherent electromagnetic immunity, the capability to sense at long distances, light weight, small size and a multiplicity of network architectures, all of which can be interrogated from a single point. Even so, fibre sensors is a niche technology, attractive only when its very special features offer substantial user benefit. There are, however, many such niches exemplified in the electrical power supply industry, in gyroscopes for navigational instruments, in hydrophones and geophones. Then there are the distributed sensing architectures that enable useful measurements of pressure, strain and temperature fields affecting the optical properties of the fibre itself to map these parameter fields as a function of position along lengths of fibre to many tens of kilometres. The fibre sensing concept spawned its own research community, and the international conference on Optical Fibre Sensors first appeared in 1983 in London then emerged into a series travelling from Europe to the Americas and into the Asia-Pacific region. The 20th in the series took place in Edinburgh at the end of 2009 and this special issue of Measurement Science and Technology presents extended versions of some of the papers that first appeared at the conference. The science and technology of fibre sensing have evolved significantly over the history of the conference, drawing on developments in optical

  13. Retained laser fibre: insights and management.

    Science.gov (United States)

    Lekich, C; Hannah, P

    2014-06-01

    To describe a case of retained endovenous laser fibre. To review the literature and Food and Drug Administration device failure reports. To suggest protocols for avoiding this complication and a method of removal. A case of retained fibre removal is described. Fibre removal techniques in vivo and ex vivo in a bovine model on the laboratory bench are presented. Successful in vivo and ex vivo fibre removal was performed using duplex ultrasound scan guided phlebectomy techniques. Unexplained measured fibre-length discrepancies due to misleading manufacturer's packaging was discovered. Simple ultrasound-guided micro-phlebectomy techniques can be used to remove retained laser fibres in the office environment. Laser fibre length measurements before and after treatment are recommended. Some preventive guidelines are described to avoid, or at least diagnose immediately, this complication, such as the 'Laser Eclipse Sign'. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  14. Characterisation of Natural Fibre Reinforcements and Composites

    Directory of Open Access Journals (Sweden)

    Richard K. Cullen

    2013-01-01

    Full Text Available Recent EU directives (e.g., ELV and WEEE have caused some rethinking of the life cycle implications of fibre reinforced polymer matrix composites. Man-made reinforcement fibres have significant ecological implications. One alternative is the use of natural fibres as reinforcements. The principal candidates are bast (plant stem fibres with flax, hemp, and jute as the current front runners. The work presented here will consider the characterisation of jute fibres and their composites. A novel technique is proposed for the measurement of fibre density. The new rule of mixtures, extended for noncircular cross-section natural fibres, is shown to provide a sensible estimate for the experimentally measured elastic modulus of the composite.

  15. Laser frequency standards based on gas-filled hollow-core fibres

    DEFF Research Database (Denmark)

    Triches, Marco

    technology, which has been widely investigated in the past decades, using many different molecular and atomic transitions as optical reference. One of the recommended references in the telecommunication region of the light spectrum is given by a specific absorption line in 13C2H2 acetylene. However, many...... into the HC fiber technology is represented by high-energy pulse delivery systems. The low non-linearity of the in-air guidance mechanism offers a unique tool to propagate unperturbed pulses far from the laser source. A tight vacuum sealed encapsulation can avoid the remaining non-linearity generated by in...

  16. Fouling autopsy of hollow-fibre MF membranes in wastewater reclamation

    OpenAIRE

    Nghiem, D. L.; Schaefer, Andrea

    2006-01-01

    Fouling in membrane filtration processes is problematic but inevitable as it occurs with the retention of contaminants that accumulate on the membrane surface. The causes of fouling are often specific, depending upon feed water constituents, the membrane, and the operation regime. Therefore, it is desirable that a thorough investigation is performed on fouled membrane elements of the affected plant. This technique is known as “membrane autopsy”, which identifies the cause of poor membrane per...

  17. Design and characterisation of SRS filtering optical fibre for pulsed fibre laser beam delivery

    Science.gov (United States)

    Vukovic, Natasha; Chan, Jaclyn S.; Gorman, Philip M.; Petrovich, Marco N.; Hayes, John R.; Malinowski, Andy; Codemard, Christophe A.; Zervas, Michalis N.

    2017-02-01

    The high performance of fibre lasers is largely due to the outstanding characteristics of fibres as an active medium. However, there is a need to overcome some limits at high optical powers which are imposed by the fibre design. We report on a design and fabrication of a stimulated Raman scattering (SRS) filtering fibre for high average or high peak optical power delivery applications. The fibre geometry is based on the series of circularly arranged high index rod resonators embedded in the silica cladding. The operation principle relies on the resonant coupling of the core and resonators modes. The fabricated fibre demonstrated wide transmission window and filtering of SRS from the output spectra (with the extinction which exceeds 20dB at the Raman Stokes wavelength), robustness for bending and high output beam quality. The fibre has been tested as a beam delivery fibre of a commercial pulsed fibre laser system in order to identify filtering performance and its limitations.

  18. Transmission properties of hollow-core photonic bandgap fibers

    DEFF Research Database (Denmark)

    Falk, Charlotte Ijeoma; Hald, Jan; Petersen, Jan C.

    2010-01-01

    Variations in optical transmission of four types of hollow-core photonic bandgap fibers are measured as a function of laser frequency. These variations influence the potential accuracy of gas sensors based on molecular spectroscopy in hollow-core fibers.......Variations in optical transmission of four types of hollow-core photonic bandgap fibers are measured as a function of laser frequency. These variations influence the potential accuracy of gas sensors based on molecular spectroscopy in hollow-core fibers....

  19. Self-organized instability in graded-index multimode fibre

    CERN Document Server

    Wright, Logan G; Nolan, Daniel A; Li, Ming-Jun; Christodoulides, Demetrios N; Wise, Frank W

    2016-01-01

    Multimode fibres (MMFs) are attracting interest for complex spatiotemporal dynamics, and for ultrafast fibre sources, imaging and telecommunications. This new interest is based on three key properties: their high spatiotemporal complexity (information capacity), the important role of disorder, and complex intermodal interactions. To date, phenomena in MMFs have been studied only in limiting cases where one or more of these properties can be neglected. Here we study MMFs in a regime in which all these elements are integral. We observe a spatial beam-cleaning process preceding spatiotemporal modulation instability. We show that the origin of these processes is a universal unstable attractor in graded-index MMFs. Both the self-organization of the attractor, as well as its instability, are caused by intermodal interactions characterized by cooperating disorder, nonlinearity and dissipation. The demonstration of a disorder-enhanced nonlinear process in MMF has important implications for telecommunications, and the...

  20. Mode Division Multiplexing Exploring Hollow-Core Photonic Bandgap Fibers

    DEFF Research Database (Denmark)

    Xu, Jing; Lyngso, Jens Kristian; Leick, Lasse

    2013-01-01

    We review our recent exploratory investigations on mode division multiplexing using hollow-core photonic bandgap fibers (HC-PBGFs). Compared with traditional multimode fibers, HC-PBGFs have several attractive features such as ultra-low nonlinearities, low-loss transmission window around 2 µm etc....... After having discussed the potential and challenges of using HC-PBGFs as transmission fibers for mode multiplexing applications, we will report a number of recent proof-of-concept results obtained in our group using direct detection receivers. The first one is the transmission of two 10.7 Gbit/s non......-return to zero (NRZ) data signals over a 30 m 7-cell HC-PBGF using the offset mode launching method. In another experiment, a short piece of 19-cell HC-PBGF was used to transmit two 20 Gbit/s NRZ channels using a spatial light modulator for precise mode excitation. Bit-error-ratio (BER) performances below...

  1. Adiabatic Rearrangement of Hollow PV Towers

    Directory of Open Access Journals (Sweden)

    Eric A Hendricks

    2010-10-01

    Full Text Available Diabatic heating from deep moist convection in the hurricane eyewall produces a towering annular structure of elevated potential vorticity (PV. This structure has been referred to as a hollow PV tower. The sign reversal of the radial gradient of PV satisfies the Charney-Stern necessary condition for combined barotropic-baroclinic instability. For thin enough annular structures, small perturbations grow exponentially, extract energy from the mean flow, and lead to hollow tower breakdown, with significant vortex structural and intensity change. The three-dimensional adiabatic rearrangements of two prototypical hurricane-like hollow PV towers (one thick and one thin are examined in an idealized framework. For both hollow towers, dynamic instability causes air parcels with high PV to be mixed into the eye preferentially at lower levels, where unstable PV wave growth rates are the largest. Little or no mixing is found to occur at upper levels. The mixing at lower and middle levels is most rapid for the breakdown of the thin hollow tower, consistent with previous barotropic results. For both hollow towers, this advective rearrangement of PV affects the tropical cyclone structure and intensity in a number of ways. First, the minimum central pressure and maximum azimuthal mean velocity simultaneously decrease, consistent with previous barotropic results. Secondly, isosurfaces of absolute angular momentum preferentially shift inward at low levels, implying an adiabatic mechanism by which hurricane eyewall tilt can form. Thirdly, a PV bridge, similar to that previously found in full-physics hurricane simulations, develops as a result of mixing at the isentropic levels where unstable PV waves grow most rapidly. Finally, the balanced mass field resulting from the PV rearrangement is warmer in the eye between 900 and 700 hPa. The location of this warming is consistent with observed warm anomalies in the eye, indicating that in certain instances the hurricane

  2. Computational predictions of zinc oxide hollow structures

    Science.gov (United States)

    Tuoc, Vu Ngoc; Huan, Tran Doan; Thao, Nguyen Thi

    2018-03-01

    Nanoporous materials are emerging as potential candidates for a wide range of technological applications in environment, electronic, and optoelectronics, to name just a few. Within this active research area, experimental works are predominant while theoretical/computational prediction and study of these materials face some intrinsic challenges, one of them is how to predict porous structures. We propose a computationally and technically feasible approach for predicting zinc oxide structures with hollows at the nano scale. The designed zinc oxide hollow structures are studied with computations using the density functional tight binding and conventional density functional theory methods, revealing a variety of promising mechanical and electronic properties, which can potentially find future realistic applications.

  3. Microfabricated hollow microneedle array using ICP etcher

    Energy Technology Data Exchange (ETDEWEB)

    Ji Jing [Mechanical Engineering National University of Singapore, 119260, Singapore (Singapore); Tay, Francis E H [Mechanical Engineering National University of Singapore, 119260, Singapore (Singapore); Miao Jianmin [MicroMachines Center, School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 (Singapore)

    2006-04-01

    This paper presents a developed process for fabrication of hollow silicon microneedle arrays. The inner hollow hole and the fluidic reservoir are fabricated in deep reactive ion etching. The profile of outside needles is achieved by the developed fabrication process, which combined isotropic etching and anisotropic etching with inductively coupled plasma (ICP) etcher. Using the combination of SF{sub 6}/O{sub 2} isotropic etching chemistry and Bosch process, the high aspect ratio 3D and high density microneedle arrays are fabricated. The generated needle external geometry can be controlled by etching variables in the isotropic and anisotropic cases.

  4. Microfabricated hollow microneedle array using ICP etcher

    Science.gov (United States)

    Ji, Jing; Tay, Francis E. H.; Miao, Jianmin

    2006-04-01

    This paper presents a developed process for fabrication of hollow silicon microneedle arrays. The inner hollow hole and the fluidic reservoir are fabricated in deep reactive ion etching. The profile of outside needles is achieved by the developed fabrication process, which combined isotropic etching and anisotropic etching with inductively coupled plasma (ICP) etcher. Using the combination of SF6/O2 isotropic etching chemistry and Bosch process, the high aspect ratio 3D and high density microneedle arrays are fabricated. The generated needle external geometry can be controlled by etching variables in the isotropic and anisotropic cases.

  5. Bioreactor design considerations for hollow organs.

    Science.gov (United States)

    Fish, Jeff; Halberstadt, Craig; McCoy, Darell W; Robbins, Neil

    2013-01-01

    There are many important considerations in the design, construction, and use of a bioreactor for growing hollow organs such as vessels, gastrointestinal tissue, esophagus, and others. The growth of new organs requires a specialized container that provides sterility and an environment conducive to cell-seeding and attachment onto a three-dimensional bioabsorbable porous scaffold, incubation, maturation, and shipping for implantation. The materials' selection, dimensions, manufacturing, testing, and use of the bioreactor are all factors that should be considered in designing a bioreactor for the development of hollow organs.

  6. Scaffold Characteristics for Functional Hollow Organ Regeneration

    Directory of Open Access Journals (Sweden)

    Daniel Eberli

    2010-01-01

    Full Text Available Many medical conditions require surgical reconstruction of hollow organs. Tissue engineering of organs and tissues is a promising new technique without harvest site morbidity. An ideal biomaterial should be biocompatible, support tissue formation and provide adequate structural support. It should degrade gradually and provide an environment allowing for cell-cell interaction, adhesion, proliferation, migration, and differentiation. Although tissue formation is feasible, functionality has never been demonstrated. Mainly the lack of proper innervation and vascularisation are hindering contractility and normal function. In this chapter we critically review the current state of engineering hollow organs with a special focus on innervation and vascularisation.

  7. Study on surface adhesion of Plasma modified Polytetrafluoroethylene hollow fiber membrane

    Science.gov (United States)

    Chen, Jiangrong; Zhang, Huifeng; Liu, Guochang; Guo, Chungang; Lv, Jinglie; Zhangb, Yushan

    2018-01-01

    Polytetrafluoroethylene (PTFE) is popular membrane material because of its excellent thermal stability, chemical stability and mechanical stability. However, the low surface energy and non-sticky property of PTFE present challenges for modification. In the present study, plasma treatment was performed to improve the surface adhesion of PTFE hollow fiber membrane. The effect of discharge voltage, treatment time on the adhesion of PTFE hollow fiber membrane was symmetrically evaluated. Results showed that the plasma treatment method contributed to improve the surface activity and roughness of PTFE hollow fiber membrane, and the adhesion strength depend significantly on discharge voltage, which was beneficial to seepage pressure of PTFE hollow fiber membrane module. The adhesion strength of PTFE membrane by plasma treated at 220V for 3min reached as high as 86.2 N, far surpassing the adhesion strength 12.7 N of pristine membrane. Furthermore, improvement of content of free radical and composition analysis changes of the plasma modified PTFE membrane were investigated. The seepage pressure of PTFE membrane by plasma treated at 220V for 3min was 0.375 MPa, which means that the plasma treatment is an effective technique to improve the adhesion strength of membrane.

  8. Conceptual design of hollow electron lenses for beam halo control in the Large Hadron Collider

    Energy Technology Data Exchange (ETDEWEB)

    Stancari, Giulio [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Previtali, Valentina [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Valishev, Alexander [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Bruce, Roderik [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Redaelli, Stefano [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Rossi, Adriana [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Salvachua Ferrando, Belen [European Organization for Nuclear Research (CERN), Geneva (Switzerland)

    2014-06-26

    Collimation with hollow electron beams is a technique for halo control in high-power hadron beams. It is based on an electron beam (possibly pulsed or modulated in intensity) guided by strong axial magnetic fields which overlaps with the circulating beam in a short section of the ring. The concept was tested experimentally at the Fermilab Tevatron collider using a hollow electron gun installed in one of the Tevatron electron lenses. We are proposing a conceptual design for applying this technique to the Large Hadron Collider at CERN. A prototype hollow electron gun for the LHC was built and tested. The expected performance of the hollow electron beam collimator was based on Tevatron experiments and on numerical tracking simulations. Halo removal rates and enhancements of halo diffusivity were estimated as a function of beam and lattice parameters. Proton beam core lifetimes and emittance growth rates were checked to ensure that undesired effects were suppressed. Hardware specifications were based on the Tevatron devices and on preliminary engineering integration studies in the LHC machine. Required resources and a possible timeline were also outlined, together with a brief discussion of alternative halo-removal schemes and of other possible uses of electron lenses to improve the performance of the LHC.

  9. Conceptual design of hollow electron lenses for beam halo control in the Large Hadron Collider

    CERN Document Server

    Stancari, Giulio; Valishev, Alexander; Bruce, Roderik; Redaelli, Stefano; Rossi, Adriana; Salvachua Ferrando, Belen

    2014-01-01

    Collimation with hollow electron beams is a technique for halo control in high-power hadron beams. It is based on an electron beam (possibly pulsed or modulated in intensity) guided by strong axial magnetic fields which overlaps with the circulating beam in a short section of the ring. The concept was tested experimentally at the Fermilab Tevatron collider using a hollow electron gun installed in one of the Tevatron electron lenses. Within the US LHC Accelerator Research Program (LARP) and the European FP7 HiLumi LHC Design Study, we are proposing a conceptual design for applying this technique to the Large Hadron Collider at CERN. A prototype hollow electron gun for the LHC was built and tested. The expected performance of the hollow electron beam collimator was based on Tevatron experiments and on numerical tracking simulations. Halo removal rates and enhancements of halo diffusivity were estimated as a function of beam and lattice parameters. Proton beam core lifetimes and emittance growth rates were check...

  10. The Hollow-Face Illusion in Infancy: Do Infants See a Screen Based Rotating Hollow Mask as Hollow?

    Directory of Open Access Journals (Sweden)

    Aki Tsuruhara

    2011-06-01

    Full Text Available We investigated whether infants experience the hollow-face illusion using a screen-based presentation of a rotating hollow mask. In experiment 1 we examined preferential looking between rotating convex and concave faces. Adults looked more at the concave—illusory convex—face which appears to counter rotate. Infants of 7- to 8-month-old infants preferred the convex face, and 5- to 6-month-olds showed no preference. While older infants discriminate, their preference differed from that of adults possibly because they don't experience the illusion or counter rotation. In experiment 2 we tested preference in 7- to 8-month-olds for angled convex and concave static faces both before and after habituation to the stimuli shown in experiment 1. The infants showed a novelty preference for the static shape opposite to the habituation stimulus, together with a general preference for the static convex face. This shows that they discriminate between convex and concave faces and that habituation to either transfers across a change in view. Seven- to eight-month-olds have been shown to discriminate direction of rigid rotation on the basis of perspective changes. Our results suggest that this, perhaps together with a weaker bias to perceive faces as convex, allows these infants to see the screen-based hollow face as hollow even though adults perceive it as convex.

  11. Fibre reinforced concrete exposed to elevated temperature

    Science.gov (United States)

    Novák, J.; Kohoutková, A.

    2017-09-01

    Although concrete when subject to fire performs very well, its behaviour and properties change dramatically under high temperature due to damaged microstructure and mesostructure. As fibre reinforced concrete (FRC) represents a complex material composed of various components with different response to high temperature, to determine its behaviour and mechanical properties in fire is a demanding task. The presented paper provides a summary of findings on the fire response of fibre FRC. Namely, the information on steel fibre reinforced concrete (SFRC), synthetic fibre reinforced concrete and hybrid (steel + synthetic) fibre reinforced concrete have been gathered from various contributions published up to date. The mechanical properties including the melting point and ignition point of fibres affect significantly the properties of concrete composites with addition of fibres. The combination of steel and synthetic fibres represents a promising alternative how to ensure good toughness of a concrete composite before heating and improve its residual mechanical behaviour and spalling resistance as well as the ductility after heating. While synthetic fibres increase concrete spalling resistance, steel fibres in a concrete mix leads to an improvement in both mechanical properties and resistance to heating effects.

  12. Fundamentals of fibre-reinforced soil engineering

    CERN Document Server

    Shukla, Sanjay Kumar

    2017-01-01

    This book is intended to serve as a one-stop reference on fibre-reinforced soils. Over the past 30-35 years, the engineering behaviour of randomly distributed/oriented fibre-reinforced soil, also called simply fibre-reinforced soil, has been investigated in detail by researchers and engineers worldwide. Waste fibres (plastic waste fibres, old tyre fibres, etc.) create disposal and environmental problems. Utilization of such fibres in construction can help resolve these concerns. Research studies and some field applications have shown that the fibres can be utilized in large quantities in geotechnical and civil engineering applications in a cost-effective and environmentally friendly manner. This book covers a complete description of fibres, their effects when included within a soil or other similar materials such as the fly ash, and their field applications. It gives a detailed view of fibre-reinforced soil engineering. The book will be useful to students, professional, and researchers alike, and can also ser...

  13. Slow-light enhanced absorption in a hollow-core fiber.

    Science.gov (United States)

    Grgić, Jure; Xiao, Sanshui; Mørk, Jesper; Jauho, Antti-Pekka; Mortensen, N Asger

    2010-06-21

    Light traversing a hollow-core photonic band-gap fiber may experience multiple reflections and thereby a slow-down and enhanced optical path length. This offers a technologically interesting way of increasing the optical absorption of an otherwise weakly absorbing material which can infiltrate the fibre. However, in contrast to structures with a refractive index that varies along the propagation direction, like Bragg stacks, the translationally invariant structures studied here feature an intrinsic trade-off between light slow-down and filling fraction that limits the net absorption enhancement. We quantify the degree of absorption enhancement that can be achieved and its dependence on key material parameters. By treating the absorption and index on equal footing, we demonstrate the existence of an absorption-induced saturation of the group index that itself limits the maximum absorption enhancement that can be achieved.

  14. Hollow circular-truncated cone resonator and its hollow variable biconical laser beam

    Science.gov (United States)

    Liu, Jinglun; Chen, Mei; Wang, Qionghua; Sun, Nianchun

    2014-05-01

    To obtain a hollow variable biconical laser beam (HVBLB), a CO2 laser having a hollow circular-truncated cone resonator (HCTCR) is presented. This HCTCR comprises a rotationally symmetric total-reflecting concave mirror at the bottom, a rotationally symmetric part-reflecting convex mirror at the top, and a hollow circular-truncated cone discharge tube at the middle. The cross section of this generated biconical laser beam changes from annulus to circular to annulus and the size of this cross section from big to small to large as the propagation distance increases. So, a kind of laser beam with variable center intensity from zero to peak value to zero is obtained and is known as HVBLB. Due to the inclusion of part of the hollow laser beam (HLB) and solid laser beam, this HVBLB requires no additional beam-shaping element and has broad applications such as optical trapping and commercial manufacturing.

  15. A discrete fibre dispersion method for excluding fibres under compression in the modelling of fibrous tissues.

    Science.gov (United States)

    Li, Kewei; Ogden, Ray W; Holzapfel, Gerhard A

    2018-01-01

    Recently, micro-sphere-based methods derived from the angular integration approach have been used for excluding fibres under compression in the modelling of soft biological tissues. However, recent studies have revealed that many of the widely used numerical integration schemes over the unit sphere are inaccurate for large deformation problems even without excluding fibres under compression. Thus, in this study, we propose a discrete fibre dispersion model based on a systematic method for discretizing a unit hemisphere into a finite number of elementary areas, such as spherical triangles. Over each elementary area, we define a representative fibre direction and a discrete fibre density. Then, the strain energy of all the fibres distributed over each elementary area is approximated based on the deformation of the representative fibre direction weighted by the corresponding discrete fibre density. A summation of fibre contributions over all elementary areas then yields the resultant fibre strain energy. This treatment allows us to exclude fibres under compression in a discrete manner by evaluating the tension-compression status of the representative fibre directions only. We have implemented this model in a finite-element programme and illustrate it with three representative examples, including simple tension and simple shear of a unit cube, and non-homogeneous uniaxial extension of a rectangular strip. The results of all three examples are consistent and accurate compared with the previously developed continuous fibre dispersion model, and that is achieved with a substantial reduction of computational cost. © 2018 The Author(s).

  16. Rare-Earth Doped Photonic Crystal Fibre Lasers and Amplifiers

    DEFF Research Database (Denmark)

    Hougaard, Kristian G.

    2005-01-01

    In this thesis, a theoretical and numerical study of the use of rare-earthdoped photonic crystal fibres as optical amplifiers and lasers, has been performed. Photonic crystal fibres or microstructured optical fibres is a new kind of optical fibre in which the cladding region typically consist....... Their novel properties allow for design of optical fibre amplifiers and fibre lasers with superior performance, compared to solutions based on conventional fibres. The primary applications considered are high efficiency fibre amplifiers based on index guiding photonic crystal fibres, and cladding pumped...

  17. Linewidth tolerance of digital coherent receiver using Viterbi & Viterbi RF carrier recovery for radio-over-fibre links

    DEFF Research Database (Denmark)

    Guerrero Gonzalez, Neil; Zibar, Darko; Larsen, Knud J.

    2009-01-01

    for phase-modulated RoF optical links (2). The RF signal processing in (2) is performed using maximum likelihood RF carrier phase estimation (2). In this paper, we investigate the performance of the proposed digital coherent receiver in (2) using feedforward Viterbi & Viterbi RF carrier recovery algorithm......Transport and distribution of wireless signals over fibre, so called Radio-over-Fibre (RoF), is an important technology in order to realize converged fibre-optic and wireless networks (1). Recently, we have proposed and experimentally demonstrated a novel DSP based digital coherent receiver...

  18. Process for the production of elementary vegetable bast fibres

    NARCIS (Netherlands)

    Zhang, Y.; Jong, de E.

    1999-01-01

    A process for the production of elementary vegetable bast fibres is provided, which process comprises the steps of a) cutting raw vegetable bast fibres to a fibre length of 8 to 400 mm, b) chemically treating the cut fibres to remove lignin and pectin compounds, c) drying the fibres obtained in step

  19. Study on durability of natural fibre concrete composites using ...

    Indian Academy of Sciences (India)

    Investigations to overcome the brittle response and limiting post-yield energy absorption of concrete led to the development of fibre reinforced concrete using discrete fibres within the concrete mass. Out of the commonly used fibres, easily available low cost natural fibres are renewable source materials. Though these fibres ...

  20. Optical fibre probes in the measurement of scattered light ...

    Indian Academy of Sciences (India)

    2014-01-08

    Jan 8, 2014 ... Optical fibre probes or optrodes often form the heart of multimode fibre-based measurements and sensors. An optrode usually comprises a bundle of multimode fibres, out of which one or more fibres are used for irradiating the sample, and the remaining fibres are used to collect the light ...

  1. factors that improve the impact responses of ukam plant fibre ...

    African Journals Online (AJOL)

    Abstract. Natural fibres around us have mechanical properties capable of making them com- pete effectively with synthetic fibres in the development of fibre reinforced com- posites. Synthetic fibres (such as glass fibres) and resins (such as polyester resin) have long been used in the development of structural components ...

  2. Factors That Improve the Impact Responses of Ukam Plant Fibre ...

    African Journals Online (AJOL)

    Natural fibres around us have mechanical properties capable of making them compete effectively with synthetic fibres in the development of fibre reinforced composites. Synthetic fibres (such as glass fibres) and resins (such as polyester resin) have long been used in the development of structural components for car bodies, ...

  3. Electromagnetic and microwave absorbing properties of hollow ...

    Indian Academy of Sciences (India)

    A mass of hollow carbon nanospheres (HCNSs) was fabricated by chemical vapour deposition of methane over Ni/Al2O3 catalyst at 600 °C. The products were ... Airworthiness Certification Technology Research and Management Centre, Civil Aviation University of China, Tianjin 300 300, China; School of Materials Science ...

  4. Comparison of Flexural Performance of Lightweight Fibre-reinforced Concrete and Normalweight Fibre-reinforced Concrete

    National Research Council Canada - National Science Library

    Ahsan Ali; Shahid Iqbal; Klaus Holschemacher; Thomas A Bier

    2017-01-01

    ...) and Lightweight Fibre-reinforced Concrete (LWFC) beam specimens. Fibres are known for their positive effect on crack control, better post-cracking behaviour under flexure and for enhancing toughness...

  5. Characterisation of Flax Fibres and Flax Fibre Composites. Being cellulose based sources of materials

    DEFF Research Database (Denmark)

    Aslan, Mustafa

    a growing interest among composite manufacturers for such low-cost and low-weight cellulosic fibre composites. In addition, wood and plant fibre based composites with thermoplastic polymeric matrices are recyclable, and they are cost attractive alternatives to oil based fibre reinforced polymer composites...... is on the relationship between the complex microstructure and the tensile properties of flax fibres and their composites, based on textile flax yarn and a thermoplastic polymeric matrix. Single flax fibres were isolated from flax fibre bundles which have been processed in two differentnsteps of natural treatments...... of composites, the effect of consolidation pressure on the tensile properties of flax fibre composites was investigated. A porosity corrected rule of mixtures model, and a volumetric composition model for composites were used to model the experimental data. Flax fibre yarns and thermoplastic low...

  6. Evidence of fire resistance of hollow-core slabs

    DEFF Research Database (Denmark)

    Hertz, Kristian Dahl; Sørensen, Lars Schiøtt; Giuliani, Luisa

    Hollow-core slabs have during the past 50 years comprised a variety of different structures with different cross-sections and reinforcement. At present the extruded hollow-core slabs without cross-reinforcement in the bottom flange and usually round or oval longitudinal channels (holes...... is therefore going on in the Netherlands about the fire resistance of hollow-core slabs. In 2014 the producers of hollow-core slabs have published a report of a project called Holcofire containing a collection of 162 fire tests on hollow-core slabs giving for the first time an overview of the fire tests made....... The present paper analyses the evidence now available for assessment of the fire resistance of extruded hollow-core slabs. The 162 fire tests from the Holcofire report are compared against the requirements for testing from the product standard for hollow-core slabs EN1168 and knowledge about the possible...

  7. Modulating effects in human diets of dietary fibre and beef, and of time and dose on the reactive microcapsule trapping of benzo[a]pyrene metabolites in the rat gastrointestinal tract.

    Science.gov (United States)

    O'Neill, I K; Bingham, S; Povey, A C; Brouet, I; Bereziat, J C

    1990-04-01

    Trapping by magnetic polyethyleneimine (PEI) microcapsules was utilized to investigate the influence in male rats of dose, human dietary composition and time-dependence on reactive metabolites of benzo[a]pyrene (B[a]P) in the gastrointestinal (GI) tract; also, PEI microcapsules modified with copper phthalocyanine tetrasulphonic acid (CPTS) were tested in vivo for trapping of endogenous mutagens having planar molecular structure. In a preliminary experiment the PEI microcapsules were administered by gavage at 0, 24 and 48 h, with [14C]B[a]P at 2 h to chow-fed BDVI rats; microcapsules were recovered from faeces collected at 24, 48 and 72 h, and then subjected to an extraction sequence showing that the trapped B[a]P metabolites were inconsistent with B[a]P diol epoxide trapping (as previously found) and unaltered by elapsed time or 5-fold dose alteration of B[a]P. Then five groups of F344 rats were fed isocalorically either one of four low-fat human diets or rat chow; in order to investigate influences of diet both on B[a]P and endogenous mutagens, half of each group was tested at 2 weeks with this PEI microcapsule/[14C]B[a]P protocol and then at 3 weeks, PEI-CPTS microcapsules (two gavages). So as to provide a cross-over comparison, the other half of each group was first tested with PEI-CPTS microcapsules followed by PEI microcapsules/[14C]B[a]P 1 week later. The human diets were prepared from cooked British foods so as to simulate the adequate intake of all nutrients required by humans; but with 3-fold differences in intake levels of beef and dietary fibre non-starch polysaccharide (NSP), while ensuring the same intake of available energy, protein, fat and calcium. They gave very similar body-weight gains in the four groups but greatly reduced faecal weight, protein and total faecal enzyme activity compared with chow; the extraction pattern of microcapsule-trapped B[a]P metabolite radioactivity was not significantly altered. However, human diet consumption caused a

  8. Durability of cracked fibre reinforced concrete structures

    DEFF Research Database (Denmark)

    Hansen, Ernst Jan De Place

    1998-01-01

    Durability studies are carried out at BKM as part of the research project "Design Methods for Fibre Reinforced Concrete" (FRC) involving BKM, The Concrete Research Center at DTI, Building Technology at Aalborg University, Rambøll, 4K-Beton and Rasmussen & Schiøtz. Concrete beams with or without...... fibre reinforcement are exposed to a combination of mechanical and environmental load to indicate whether fibre reinforcement will improve the durability of cracked concrete structures. Secondly, it is the aim to identify important mechanisms for the effect of the fibre reinforcement on the durability......) and polypropylene fibres (PP) are used in the concrete beams as well as main reinforcement. Results of the durability tests on cracked FRC-beams are compared with results for uncracked FRC-beams and beams without fibres....

  9. Frost resistance of fibre reinforced concrete structures

    DEFF Research Database (Denmark)

    Hansen, Ernst Jan De Place

    1999-01-01

    of 0.4-1% by volume of fibres cannot replace air entrainment in order to secure a frost resistant concrete; the minimum amount of air needed to make the concrete frost resistant is not changed when adding fibres· the amount of air entrainment must be increased when fibres are added to establish......Frost resistance of fibre reinforced concrete with 2.5-4.2% air and 6-9% air (% by volume in fresh concrete) casted in the laboratory and in-situ is compared. Steel fibres with hooked ends (ZP, length 30 mm) and polypropylene fibres (PP, CS, length 12 mm) are applied. It is shown that· addition...

  10. Interfaces between a fibre and its matrix

    DEFF Research Database (Denmark)

    Lilholt, Hans; Sørensen, Bent F.

    2017-01-01

    The interface between a fibre and its matrix represents an important element in the characterization and exploitation of composite materials. Both theoretical models and analyses of experimental data have been presented in the literature since modern composite were developed and many experiments......, the interfacial energy [J/m2], the interfacial frictional shear stress [MPa] and the mismatch strain [-] between fibre and matrix. The model has been used for the different modes of fibre pull-out and fibre fragmentation. In this paper it is demonstrated that the governing equations for the experimental...... parameters (applied load, debond length and relative fibre/matrix displacement) are rather similar for these test modes. A simplified analysis allows the direct determination of the three interface parameters from two plots for the experimental data. The complete analysis is demonstrated for steel fibres...

  11. Fibre architecture and song activation rates of syringeal muscles are not lateralized in the European starling.

    Science.gov (United States)

    Uchida, A M; Meyers, R A; Cooper, B G; Goller, F

    2010-04-01

    The songbird vocal organ, the syrinx, is composed of two sound generators, which are independently controlled by sets of two extrinsic and four intrinsic muscles. These muscles rank among the fastest vertebrate muscles, but the molecular and morphological foundations of this rapid physiological performance are unknown. Here we show that the four intrinsic muscles in the syrinx of male European starlings (Sturnus vulgaris) are composed of fast oxidative and superfast fibres. Dorsal and ventral tracheobronchialis muscles contain slightly more superfast fibres relative to the number of fast oxidative fibres than dorsal and ventral syringealis muscles. This morphological difference is not reflected in the highest, burst-like activation rate of the two muscle groups during song as assessed with electromyographic recordings. No difference in fibre type ratio was found between the corresponding muscles of the left and right sound generators. Airflow and electromyographic measurements during song indicate that maximal activation rate and speed of airflow regulation do not differ between the two sound sources. Whereas the potential for high-speed muscular control exists on both sides, the two sound generators are used differentially for modulation of acoustic parameters. These results show that large numbers of superfast fibre types are present in intrinsic syringeal muscles of a songbird, providing further confirmation of rapid contraction kinetics. However, syringeal muscles are composed of two fibre types which raises questions about the neuromuscular control of this heterogeneous muscle architecture.

  12. Multi-Functional Fibre-Optic Microwave Links

    DEFF Research Database (Denmark)

    Gliese, Ulrik Bo

    1998-01-01

    GHz RF carrier. The frequency converting link demonstrates up-conversion of a 100 Mbit/s PSK signal from a 2 GHz carrier to a 9 GHz carrier with penalty-free transmission over 25 km of optical fibre. Finally, the transparent signal recovering link transmits a standard FM video 7.6 GHz radio......-optic microwave links. The resulting links are inherently transparent and mainly used for signal transmission. As opposed to direct detection links, remote heterodyne detection links can directly perform functionalities such as modulation, frequency conversion, and transparent signal recovery in addition...... to signal transmission. All three functionalities are presented and experimentally demonstrated with a remote heterodyne detection link based on a dual-frequency laser transmitter with two offset phase locked semiconductor lasers. In the modulating link a 1 Gbit/s baseband signal is QPSK modulated onto a 9...

  13. Non-Invasive Study of Nerve Fibres using Laser Interference Microscopy

    DEFF Research Database (Denmark)

    Brazhe, A. R.; Brazhe, N. A.; Rodionova, N. N.

    2008-01-01

    This paper presents the results of a laser interference microscopy study of the morphology and dynamical properties of myelinated nerve fibres. We describe the principles of operation of the phase-modulated laser interference microscope and show how this novel technique allows us to obtain...

  14. Linear and nonlinear resonance features of an erbium-doped fibre ...

    Indian Academy of Sciences (India)

    The continuous-wave output of a single-mode erbium-doped fibre ring laser when subjected to cavity-loss modulation is found to exhibit linear as well as nonlinear resonances. At sufficiently low driving amplitude, the system resembles a linear damped oscillator. At higher amplitudes, the dynamical study of these ...

  15. Towards the Knittability of Graphene Oxide Fibres.

    Science.gov (United States)

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

    2015-10-13

    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.

  16. A novel photonic crystal fibre switch

    DEFF Research Database (Denmark)

    Alkeskjold, Thomas Tanggaard; Hermann, D.S.; Broeng, Jes

    2003-01-01

    A new thermo-optic fibre switch is demonstrated, which utilizes the phase transitions of a thermochromic liquid crystal inside a photonic crystal fibre. We report an extinction ratio of 60 dB and an insertion loss of 1 dB.......A new thermo-optic fibre switch is demonstrated, which utilizes the phase transitions of a thermochromic liquid crystal inside a photonic crystal fibre. We report an extinction ratio of 60 dB and an insertion loss of 1 dB....

  17. Structural and functional assessment of skin nerve fibres in small-fibre pathology.

    Science.gov (United States)

    Karlsson, P; Nyengaard, J R; Polydefkis, M; Jensen, T S

    2015-09-01

    Damage to nociceptor nerve fibres may give rise to peripheral neuropathies, some of which are pain free and some are painful. A hallmark of many peripheral neuropathies is the loss of small nerve fibres in the epidermis, a condition called small-fibre neuropathy (SFN) when it is predominantly the small nerve fibres that are damaged. Historically, SFN has been very difficult to diagnose as clinical examination and nerve conduction studies mainly detect large nerve fibres, and quantitative sensory testing is not sensitive enough to detect small changes in small nerve fibres. However, taking a 3-mm punch skin biopsy from the distal leg and quantification of the nerve fibre density has proven to be a useful method to diagnose SFN. However, the correlation between the nerve fibre loss and other test results varies greatly. Recent studies have shown that it is possible not only to extract information about the nerve fibre density from the biopsies but also to get an estimation of the nerve fibre length density using stereology, quantify sweat gland innervation and detect morphological changes such as axonal swelling, all of which may be additional parameters indicating diseased small fibres relating to symptoms reported by the patients. In this review, we focus on available tests to assess structure and function of the small nerve fibres, and summarize recent advances that have provided new possibilities to more specifically relate structural findings with symptoms and function in patients with SFN. © 2014 European Pain Federation - EFIC®

  18. Abaca fibre reinforced PP composites and comparison with jute and flax fibre PP composites

    Directory of Open Access Journals (Sweden)

    2007-11-01

    Full Text Available Abaca fibre reinforced PP composites were fabricated with different fibre loadings (20, 30, 40, 50wt% and in some cases 35 and 45 wt%. Flax and jute fibre reinforced PP composites were also fabricated with 30 wt% fibre loading. The mechanical properties, odour emission and structure properties were investigated for those composites. Tensile, flexural and Charpy impact strengths were found to increase for fibre loadings up to 40 wt% and then decreased. Falling weight impact tests were also carried out and the same tendency was observed. Owing to the addition of coupling agent (maleated polypropylene -MAH-PP, the tensile, flexural and falling weight impact properties were found to increase in between 30 to 80% for different fibre loadings. When comparing jute and flax fibre composites with abaca fibre composites, jute fibre composites provided best tensile properties but abaca fibre polypropylene composites were shown to provide best notch Charpy and falling weight impact properties. Odours released by flax fibre composites were smaller than jute and abaca fibre composites.

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

    Science.gov (United States)

    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.

  20. Self-organized instability in graded-index multimode fibres

    Science.gov (United States)

    Wright, Logan G.; Liu, Zhanwei; Nolan, Daniel A.; Li, Ming-Jun; Christodoulides, Demetrios N.; Wise, Frank W.

    2016-12-01

    Multimode fibres (MMFs) are attracting interest in the study of spatiotemporal dynamics as well as in the context of ultrafast fibre sources, imaging and telecommunications. This interest stems from three differences compared with single-mode fibre structures: their spatiotemporal complexity (information capacity), the role of disorder, and their complex intermodal interactions. To date, MMFs have been studied in limiting cases in which one or more of these properties can be neglected. Here, we study a regime in which all these elements are integral. We observe a spatial beam-cleaning phenomenon that precedes spatiotemporal modulation instability. We provide evidence that the origin of these processes is a universal unstable attractor in graded-index MMFs. The self-organization and instability of the attractor are both caused by intermodal interactions characterized by cooperating disorder, nonlinearity and dissipation. Disorder-enhanced nonlinear processes in MMFs have important implications for future telecommunications, and the multifaceted nature of the considered dynamics showcases MMFs as potential laboratories for a variety of topics in complexity science.

  1. Osmosensation in TRPV2 dominant negative expressing skeletal muscle fibres

    Science.gov (United States)

    Zanou, Nadège; Mondin, Ludivine; Fuster, Clarisse; Seghers, François; Dufour, Inès; de Clippele, Marie; Schakman, Olivier; Tajeddine, Nicolas; Iwata, Yuko; Wakabayashi, Shigeo; Voets, Thomas; Allard, Bruno; Gailly, Philippe

    2015-01-01

    Abstract Increased plasma osmolarity induces intracellular water depletion and cell shrinkage followed by activation of a regulatory volume increase (RVI). In skeletal muscle, this is accompanied by transverse tubule (TT) dilatation and by a membrane depolarization responsible for a release of Ca2+ from intracellular pools. We observed that both hyperosmotic shock-induced Ca2+ transients and RVI were inhibited by Gd3+, ruthenium red and GsMTx4 toxin, three inhibitors of mechanosensitive ion channels. The response was also completely absent in muscle fibres overexpressing a non-permeant, dominant negative (DN) mutant of the transient receptor potential, V2 isoform (TRPV2) ion channel, suggesting the involvement of TRPV2 or of a TRP isoform susceptible to heterotetramerization with TRPV2. The release of Ca2+ induced by hyperosmotic shock was increased by cannabidiol, an activator of TRPV2, and decreased by tranilast, an inhibitor of TRPV2, suggesting a role for the TRPV2 channel itself. Hyperosmotic shock-induced membrane depolarization was impaired in TRPV2-DN fibres, suggesting that TRPV2 activation triggers the release of Ca2+ from the sarcoplasmic reticulum by depolarizing TTs. RVI requires the sequential activation of STE20/SPS1-related proline/alanine-rich kinase (SPAK) and NKCC1, a Na+–K+–Cl− cotransporter, allowing ion entry and driving osmotic water flow. In fibres overexpressing TRPV2-DN as well as in fibres in which Ca2+ transients were abolished by the Ca2+ chelator BAPTA, the level of P-SPAKSer373 in response to hyperosmotic shock was reduced, suggesting a modulation of SPAK phosphorylation by intracellular Ca2+. We conclude that TRPV2 is involved in osmosensation in skeletal muscle fibres, acting in concert with P-SPAK-activated NKCC1. Key points Increased plasma osmolarity induces intracellular water depletion and cell shrinkage (CS) followed by activation of a regulatory volume increase (RVI). In skeletal muscle, the hyperosmotic shock

  2. Blast Resistance of Slurry Infiltrated Fibre Concrete with Waste Steel Fibres from Tires

    Directory of Open Access Journals (Sweden)

    Drdlová Martina

    2018-01-01

    Full Text Available The utilization of waste steel fibres (coming from the recycling process of the old tires in production of blast resistant cement based panels was assessed. Waste fibres were incorporated in slurry infiltrated fibre concrete (SIFCON, which is a special type of ultra-highperformance fibre reinforced concrete with high fibre content. The technological feasibility (i.e. suitability of the waste fibres for SIFCON technology was assessed using homogeneity test. Test specimens were prepared with three volume fractions (5; 7.5 and 10 % by vol. of waste unclassified fibres. SIFCON with industrial steel fibres (10% by vol. and ultra-highperformance fibre concrete with industrial fibres were also cast and tested for comparison purposes. Quasi-static mechanical properties were determined. Real blast tests were performed on the slab specimens (500x500x40 mm according to the modified methodology M-T0-VTU0 10/09. Damage of the slab, the change of the ultrasound wave velocity propagation in the slab specimen before and after the blast load in certain measurement points, the weight of fragments and their damage potential were evaluated and compared. Realized tests confirmed the possibility of using the waste fibres for SIFCON technology. The obtained results indicate, that the usage of waste fibres does not significantly reduce the values of SIFCON flexural and compressive strength at quasi-static load - the values were comparable to the specimens with industrially produced fibres. With increasing fibre content, the mechanical parameters are increasing as well. Using of the waste fibres reduces fragmentation of SIFCON at blast load due to the fibre size parameters. Using of low diameter fibres means more fibres in the matrix and thus better homogeneity of the whole composite with less unreinforced areas. Regarding the blast tests, the specimen with waste steel fibres showed the best resistance and outperformed also the specimen with commercial fibres. Using of

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

    Energy Technology Data Exchange (ETDEWEB)

    López-Buendía, Angel M., E-mail: buendia@uv.es [AIDICO Technological Institute of Construction, Benjamin Franklin 17, 46380 Paterna, Valencia (Spain); Romero-Sánchez, María Dolores [AIDICO Technological Institute of Construction, Marble Technical Unit, Camí de Castella 4, 03660 Novelda. Alicante (Spain); Climent, Verónica [Lafarge Cementos, Polígono Sepes, Isaac Newton s/n, 46500 Sagunto, Valencia (Spain); Guillem, Celia [AIDICO Technological Institute of Construction, Marble Technical Unit, Camí de Castella 4, 03660 Novelda. Alicante (Spain)

    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.

  4. Optical fibre probes in the measurement of scattered light ...

    Indian Academy of Sciences (India)

    2014-01-08

    based mea- surements and sensors. An optrode usually comprises a bundle of multimode fibres, out of which one or more fibres are used for irradiating the sample, and the remaining fibres are used to collect the.

  5. High-speed signal processing using highly nonlinear optical fibres

    DEFF Research Database (Denmark)

    Peucheret, Christophe; Oxenløwe, Leif Katsuo; Mulvad, Hans Christian Hansen

    2009-01-01

    We review recent progress in all-optical signal processing techniques making use of conventional silica-based highly nonlinear fibres. In particular, we focus on recent demonstrations of ultra-fast processing at 640 Gbit/s and above, as well as on signal processing of novel modulation formats...... relying on the phase of the optical field. Topics covered include all-optical switching of 640 Gbit/s and 1.28 Tbit/s serial data, wavelength conversion at 640 Gbit/s, optical amplitude regeneration of differential phase shift keying (DPSK) signals, as well as midspan spectral inversion for differential 8......-state phase shift keying (D8PSK) signals....

  6. LHCb Scintillating Fibre Tracker: Test Beam Report 2015

    CERN Document Server

    Rodrigues Cavalcante, Ana Barbara; Gavardi, Laura; Girard, Olivier Goran; Greim, Roman; Haefeli, Guido; Han, Xiaoxue; Joram, Christian; Kecke, Matthieu; Kuonen, Axel Kevin; Leverington, Blake Dean; Mitzel, Dominik Stefan; Muller, Janine; Neuner, Max; Nieswand, Simon; Tekampe, Tobias

    2015-01-01

    This document summarizes the testbeam results of scintillating fibre mats tested at the SPS at CERN in May and November of 2015. Fibre mats consisting of 5, 6, and 8 layers (with a wider pitch) were tested for their light yield, attenuation length, single hit efficiency, and position resolution. In November 2016, one 6-layer module was additionally irradiated to the LHCb-Upgrade dose profile for fibre mats next to the beam pipe. The loss in signal was measured near the mirror.

  7. Wet spinning PAN-fibres from aqueous solutions of ZnCl2 and NaSCN

    Science.gov (United States)

    Köhler, T.; Peterek, S.; Gries, T.

    2017-10-01

    In 2007 a chemical regulation order was adopted in Europe and China, to protect the environment and human beings from hazardous substances in consumer goods and their working environment. It is a topic of interest for the rest of the world, as well. Some substances are banned by law from industrial application. The organic solvents Dimethylformamide (DMF) and Dimethylacetamide (DMAc) are candidates for prohibition. To be prepared, the producers of carbon fibres, hollow fibres and wet spun textile products are looking for alternative solvents for their production processes and try to gain according process Know- How. Aqueous solutions of inorganic salts are the most promising alternative. Within this work, the the major differences between the organic and inorganic solvents are shown and the effects on the production costs are shown. This should show the chances which are linked with the use of the alternative solvents.

  8. Demonstration of a positron beam-driven hollow channel plasma wakefield accelerator.

    Science.gov (United States)

    Gessner, Spencer; Adli, Erik; Allen, James M; An, Weiming; Clarke, Christine I; Clayton, Chris E; Corde, Sebastien; Delahaye, J P; Frederico, Joel; Green, Selina Z; Hast, Carsten; Hogan, Mark J; Joshi, Chan; Lindstrøm, Carl A; Lipkowitz, Nate; Litos, Michael; Lu, Wei; Marsh, Kenneth A; Mori, Warren B; O'Shea, Brendan; Vafaei-Najafabadi, Navid; Walz, Dieter; Yakimenko, Vitaly; Yocky, Gerald

    2016-06-02

    Plasma wakefield accelerators have been used to accelerate electron and positron particle beams with gradients that are orders of magnitude larger than those achieved in conventional accelerators. In addition to being accelerated by the plasma wakefield, the beam particles also experience strong transverse forces that may disrupt the beam quality. Hollow plasma channels have been proposed as a technique for generating accelerating fields without transverse forces. Here we demonstrate a method for creating an extended hollow plasma channel and measure the wakefields created by an ultrarelativistic positron beam as it propagates through the channel. The plasma channel is created by directing a high-intensity laser pulse with a spatially modulated profile into lithium vapour, which results in an annular region of ionization. A peak decelerating field of 230 MeV m(-1) is inferred from changes in the beam energy spectrum, in good agreement with theory and particle-in-cell simulations.

  9. PVDF hollow fiber and nanofiber membranes for fresh water reclamation using membrane distillation

    KAUST Repository

    Francis, Lijo

    2013-11-26

    Polyvinylidene fluoride hollow fiber and nanofibrous membranes are engineered and successfully fabricated using dry-jet wet spinning and electrospinning techniques, respectively. Fabricated membranes are characterized for their morphology, average pore size, pore size distribution, nanofiber diameter distribution, thickness, and water contact angle. Direct contact membrane distillation (DCMD) performances of the fabricated membranes have been investigated using a locally designed and fabricated, fully automated MD bench scale unit and DCMD module. Electrospun nanofibrous membranes showed a water flux as high as 36 L m-2 h-1 whereas hollow fiber membranes showed a water flux of 31.6 L m-2 h-1, at a feed inlet temperature of 80 °C and at a permeate inlet temperature of 20 °C.

  10. Properties of self-compacting fibre reinforced concrete

    OpenAIRE

    Vandewalle, Lucie; Heirman, Gert

    2009-01-01

    The postcracking behaviour of fibre reinforced concrete is particularly influenced by the fibre distribution and the fibre orientation. One could suppose that in self-compacting fibre reinforced concrete (SCFRC) fibres orient along the flow due to the wall-effect, the flow direction and the velocity profile in the concrete. To investigate the fresh and hardened characteristics (mechanical properties, orientation and distribution of the fibres) of SCFRC and to relate them to those of tradition...

  11. Inhibition of starch absorption by dietary fibre. A comparative study of wheat bran, sugar-beet fibre, and pea fibre

    DEFF Research Database (Denmark)

    Hamberg, O; Rumessen, J J; Gudmand-Høyer, E

    1989-01-01

    in H2 excretion occurred in all subjects; the calculated fractions of unabsorbed starch ranged from 4% to 17% (median, 8%). Concurrent ingestion of this bread with either wheat bran, sugar-beet fibre, or pea fibre increased the fraction of unabsorbed starch to 12.5% (5-22%) (p less than 0.05), 12.5% (5...

  12. Human hepatocyte functions in a crossed hollow fiber membrane bioreactor.

    Science.gov (United States)

    De Bartolo, Loredana; Salerno, Simona; Curcio, Efrem; Piscioneri, Antonella; Rende, Maria; Morelli, Sabrina; Tasselli, Franco; Bader, Augustinus; Drioli, Enrico

    2009-05-01

    An important challenge in liver tissue engineering is the development of bioartificial systems that are able to favour the liver reconstruction and to modulate liver cell behaviour. A crossed hollow fiber membrane bioreactor was developed to support the long-term maintenance and differentiation of human hepatocytes. The bioreactor consists of two types of hollow fiber (HF) membranes with different molecular weight cut-off (MWCO) and physico-chemical properties cross-assembled in alternating manner: modified polyetheretherketone (PEEK-WC) and polyethersulfone (PES), used for the medium inflow and outflow, respectively. The combination of these two fiber set produces an extracapillary network for the adhesion of cells and a high mass exchange through the cross-flow of culture medium. The transport of liver specific products such as albumin and urea together with the transport of drug such as diazepam was modelled and compared with the experimental metabolic data. The theoretical metabolite concentration differed 7.5% for albumin and 5% for urea with respect to experimental data. The optimised perfusion conditions of the bioreactor allowed the maintenance of liver functions in terms of urea synthesis, albumin secretion and diazepam biotransformation up to 18 days of culture. In particular the good performance of the bioreactor was confirmed by the high rate of urea synthesis (28.7 microg/h 10(6) cells) and diazepam biotransformation. In the bioreactor human hepatocytes expressed at high levels the individual cytochrome P450 isoenzymes involved in the diazepam metabolism. The results demonstrated that crossed HF membrane bioreactor is able to support the maintenance of primary human hepatocytes preserving their liver specific functions for all investigated period. This device may be a potential tool in the liver tissue engineering for drug metabolism/toxicity testing and study of disease pathogenesis alternatively to animal experimentation.

  13. Influence of surface remodelling using burs on the macro and micro surface morphology of anatomically formed fibre posts.

    Science.gov (United States)

    Plotino, G; Grande, N M; Pameijer, C H; Somma, F

    2008-04-01

    To evaluate the effect of modifying preformed fibre-reinforced composite (FRC) endodontic posts on their surface morphology and to determine how this procedure affects the integrity of the posts. Surfaces of 10 preformed glass-fibre posts (group 1) and carbon-fibre posts (group 2) were compared with those of individually formed glass-fibre posts (group 3). Ten FRC posts were modelled in order to give them a shape as close as possible to the anatomy of oval root canals. Starting from a preformed cylindrical fibre post 2.5 mm in diameter, it was modelled in such a way as to passively occupy the entire post-space length, using a cast previously created as a guide. Microscopic analyses (optical stereomicroscope and scanning electron microscope) of the post surfaces revealed similar features in all three groups. All posts had regular surfaces after cutting with a diamond bur. Smear layer mainly attributable to the cutting procedures covered the cut surface of some specimens. In conclusion, modulation of a fibre post using a diamond-coated bur did not show a loss of integrity of the post. *Because of the importance of micromechanical retention, the surface integrity of fibre posts may be important for adhesion between post and composite resin. *Modification of a fibre post using a diamond-coated bur did not damage the surface integrity of the posts. *Fibre posts can be ground to a different shape without losing their surface integrity, resulting in posts with a surface that is not visibly different from unmodified commercially available fibre posts.

  14. A PHOTONIC BAND GAP FIBRE

    DEFF Research Database (Denmark)

    1999-01-01

    An optical fibre having a periodicidal cladding structure provididing a photonic band gap structure with superior qualities. The periodical structure being one wherein high index areas are defined and wherein these are separated using a number of methods. One such method is the introduction...... of additional low index elements, another method is providing elongated elements deformed in relation to a circular cross section. Also described is a cladding structure comprising elongated elements of a material having an index of refraction higher than that of the material adjacent thereto. Using...

  15. Hollow Fiber Membrane Dehumidification Device for Air Conditioning System

    Directory of Open Access Journals (Sweden)

    Baiwang Zhao

    2015-11-01

    Full Text Available In order to provide a comfortable living and working environment indoors in tropical countries, the outdoor air often needs to be cooled and dehumidified before it enters the rooms. Membrane separation is an emerging technology for air dehumidification and it is based on the solution diffusion mechanism. Water molecules are preferentially permeating through the membranes due to its smaller kinetic diameter and higher condensability than the other gases. Compared to other dehumidification technologies such as direct cooling or desiccation, there is no phase transition involved in membrane dehumidification, neither the contact between the fresh air stream and the desiccants. Hence, membrane dehumidification would not only require less energy consumption but also avoid cross-contamination problems. A pilot scale air dehumidification system is built in this study which comprises nine pieces of one-inch PAN/PDMS hollow fiber membrane modules. A 150 h long-term test shows that the membrane modules has good water vapor transport properties by using a low vacuum force of only 0.78 bar absolute pressure at the lumen side. The water vapor concentration of the feed humid air decreases dramatically from a range of 18–22 g/m3 to a range of 13.5–18.3 g/m3. Most importantly, the total energy saving is up to 26.2% compared with the conventional air conditioning process.

  16. Hollow Fiber Membrane Dehumidification Device for Air Conditioning System.

    Science.gov (United States)

    Zhao, Baiwang; Peng, Na; Liang, Canzeng; Yong, Wai Fen; Chung, Tai-Shung

    2015-11-16

    In order to provide a comfortable living and working environment indoors in tropical countries, the outdoor air often needs to be cooled and dehumidified before it enters the rooms. Membrane separation is an emerging technology for air dehumidification and it is based on the solution diffusion mechanism. Water molecules are preferentially permeating through the membranes due to its smaller kinetic diameter and higher condensability than the other gases. Compared to other dehumidification technologies such as direct cooling or desiccation, there is no phase transition involved in membrane dehumidification, neither the contact between the fresh air stream and the desiccants. Hence, membrane dehumidification would not only require less energy consumption but also avoid cross-contamination problems. A pilot scale air dehumidification system is built in this study which comprises nine pieces of one-inch PAN/PDMS hollow fiber membrane modules. A 150 h long-term test shows that the membrane modules has good water vapor transport properties by using a low vacuum force of only 0.78 bar absolute pressure at the lumen side. The water vapor concentration of the feed humid air decreases dramatically from a range of 18-22 g/m³ to a range of 13.5-18.3 g/m³. Most importantly, the total energy saving is up to 26.2% compared with the conventional air conditioning process.

  17. Surface functionalized hollow silica particles and composites

    KAUST Repository

    Rodionov, Valentin

    2017-05-26

    Composition comprising hollow spherical silica particles having outside particle walls and inside particle walls, wherein the particles have an average particle size of about 10 nm to about 500 nm and an average wall thickness of about 10 nm to about 50 nm; and wherein the particles are functionalized with at least one organic functional group on the outside particle wall, on the inside particle wall, or on both the outside and inside particle walls, wherein the organic functional group is in a reacted or unreacted form. The organic functional group can be epoxy. The particles can be mixed with polymer precursor or a polymer material such as epoxy to form a prepreg or a nanocomposite. Lightweight but strong materials can be formed. Low loadings of hollow particles can be used.

  18. Mesoporous hollow spheres from soap bubbling.

    Science.gov (United States)

    Yu, Xianglin; Liang, Fuxin; Liu, Jiguang; Lu, Yunfeng; Yang, Zhenzhong

    2012-02-01

    The smaller and more stable bubbles can be generated from the large parent bubbles by rupture. In the presence of a bubble blowing agent, hollow spheres can be prepared by bubbling a silica sol. Herein, the trapped gas inside the bubble acts as a template. When the porogen, i.e., other surfactant, is introduced, a mesostructured shell forms by the co-assembly with the silica sol during sol-gel process. Morphological evolution emphasizes the prerequisite of an intermediate interior gas flow rate and high exterior gas flow rate for hollow spheres. The method is valid for many compositions from inorganic, polymer to their composites. Copyright © 2011 Elsevier Inc. All rights reserved.

  19. Space Charge Mitigation by Hollow Bunches

    CERN Multimedia

    Oeftiger, AO

    2014-01-01

    To satisfy the requirements of the HL-LHC (High Luminosity Large Hadron Collider), the LHC injector chain will need to supply a higher brightness, i.e. deliver the same transverse beam emittances \\epsilon_{x,y} while providing a higher intensity N. However, a larger number of particles per bunch enhances space charge effects. One approach to mitigate the impact of space charge is to change the longitudinal phase space distribution: hollow bunches feature a depleted bunch centre and a densely populated periphery. Thus, the spatial line density maximum is depressed which ultimately decreases the tune spread imposed by space charge. Therefore, a higher intensity can be accepted while keeping the same overall space charge tune shift. 3 different methods to create hollow bunches in the PSBooster are simulated.

  20. Corchorus Corchorus triden L.) PLANT FIBRE

    African Journals Online (AJOL)

    eobe

    Keywords: Bumper, Plant Fibre, Composite, Epoxy, Impact Test, Drop Weight Test. 1. INTRODUCTION. INTRODUCTION ... absorber made of different materials and configurations [20, 21]. The function of a bumper is to absorb ..... Yang Le, “Life cycle assessment of nanocellulose- reinforced advanced fibre composites”, ...

  1. Durability of fibre reinforced concrete structures

    DEFF Research Database (Denmark)

    Hansen, Ernst Jan De Place; Hansen, Kurt Kielsgaard

    1996-01-01

    The planned research will indicate, whether fibre reinforced concrete has better or worse durability than normal concrete. Durability specimens will be measured on cracked as well as uncracked specimens. Also the pore structure in the concrete will be characterized.Keywords: Fibre reinforced...... concrete, durability, pore structure, mechanical load...

  2. Fibre positioning algorithms for the WEAVE spectrograph

    NARCIS (Netherlands)

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

    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

  3. Insertion of optic fibre for CMS

    CERN Multimedia

    Maximilien Brice

    2003-01-01

    The MicroJET system uses high pressure to carefully put the optical fibres into their protective tubes. These fibres are vital for rapid data transfer, but are also very delicate and, if damanged, may not work at the required efficiency. Similiar methods are used to install cables for the telecommunications industry.

  4. Recent advances in poled optical fibres

    DEFF Research Database (Denmark)

    Pruneri, V.; Margulis, W.; Myrén, N.

    2005-01-01

    A second-order nonlinearity can be induced in optical fibres through poling. We describe accomplishments of the EU project GLAMOROUS in making low-cost high performance electrooptic and nonlinear optical fibre- and waveguide-based components. In particular a comparison with more traditional...

  5. Microstructural characterization of stone wool fibre network

    DEFF Research Database (Denmark)

    Chapelle, Lucie; Brøndsted, Povl; Kusano, Yukihiro

    2014-01-01

    Understanding the mechanical properties of fibrous network as complex as stone wool materials requires a relevant description of their microstructure and architecture. In this study, different methods have been proposed to characterize the fibre orientation, diameter and length of fibres as well ...

  6. Mohair, cashmere and other animal hair fibres

    CSIR Research Space (South Africa)

    Hunter, L

    2012-11-01

    Full Text Available Although luxury animal fibres, excluding silk, represent far less than 0.1% of global fibre production, they play a very significant role in the luxury, high value-added end of the market, notably the apparel market, being renowned for their special...

  7. Selective filling of Photonic Crystal Fibres

    DEFF Research Database (Denmark)

    Nielsen, Kristian; Noordegraaf, Danny; Sørensen, Thorkild

    2005-01-01

    A model for calculating the time necessary for filling one or more specific holes in a photonic crystal fibre is made. This model is verified for water, and its enabling potential is illustrated by a polymer application. Selective filling of the core in an air-guide photonic crystal fibre is demo...

  8. Multifunctional Carbon Fibre Tapes for Automotive Composites

    Science.gov (United States)

    Koncherry, V.; Potluri, P.; Fernando, A.

    2017-04-01

    Cabon fibre composites are used where mechanical performance such as strength, stiffness and impact properties at low density is a critical parameter for engineering applications. Carbon fibre flat tape is one material which is traditionally used to manufacture three-dimensional composites in this area. Modifying the carbon fibre tape to incorporate other functions such as stealth, electromagnetic interference, shielding, de-icing, self-repair, energy storage, allows us to create multi-functional carbon fibre tape. Researchers have been developing such material and the technology for their manufacture in order to produce multifunctional carbon fibre based components more economically and efficiently. This paper presents the manufacturing process of a metallised carbon fibre material for a chopped fibre preforming process that uses electromagnets for preforming instead of traditional suction airflow fibre deposition. In addition, the paper further presents mechanical and magneto-static modelling that is carried out to investigate the bending properties of the material produced and its suitability for creating 3D preforms.

  9. Cotton fibre cross-section properties

    Science.gov (United States)

    From a structural perspective the cotton fibre is a singularly discrete, elongated plant cell with no junctions or inter-cellular boundaries. Its form in nature is essentially unadulterated from the field to the spinning mill where its cross-section properties, as for any textile fibre, are central ...

  10. Strength variability of single flax fibres

    DEFF Research Database (Denmark)

    Aslan, Mustafa; Chinga-Carrasco, G.; Sørensen, Bent F.

    2011-01-01

    (linear and nonlinear) of the fibres are found to be correlated with the amount of defects. The linear stress–strain curves tend to show a higher tensile strength, a higher Young’s modulus, and a lower strain to failure than the nonlinear curves. Finally, the fibres are found to fracture by a complex...

  11. The glass story: fibre optic cable

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    2000-12-01

    Fibre optic cable has become the glamour pinup among cables as a result of its ability to carry billions of digital bits of information per second. Fibre optic cables consist of hair-thin fibres of high purity silica glass; enclosed in its protective shield and glass cladding, the cable is immune to electromagnetic interference and carries out its task without the need for boosting. It is the perfect answer to the ever-increasing need for speed and capacity of today's high-speed computers. This paper describes the nature of fibre optics, the two major optical fibre categories of multi-mode and single-mode, and the various possible applications for each type. Although the optical performance of fibres is relatively standardized regardless of the manufacturer, physical characteristics do vary across the industry. Fibre type and fibre parameters are usually defined by the transmission system application, whereas the cable design is usually determined by the physical environment of the particular installation. 1 tab., 5 figs.

  12. low pump power photonic crystal fibre amplifiers

    DEFF Research Database (Denmark)

    Hougaard, Kristian G.; Broeng, Jes; Bjarklev, Anders Overgaard

    2003-01-01

    Designs of low pump power optical amplifiers, based on photonic crystal fibres are presented. The potential of these fibre amplifiers is investigated, and it is demonstrated that such amplifiers may deliver gains of more than 15 dB at 1550 nm with less than 1 mW of optical pump power....

  13. Fibre optic cables for the ALICE experiment

    CERN Multimedia

    Maximilien Brice

    2003-01-01

    These thin fibres will transmit the signal received in detectors at the ALICE experiment when it starts up with the LHC in 2008. The analogue signals produced in the detectors are first converted into digital pulse, which are transported in light down such fibres. Computers then read this digital signal to produce the final set of data.

  14. GLUT4 expression at the plasma membrane is related to fibre volume in human skeletal muscle fibres

    DEFF Research Database (Denmark)

    Gaster, M; Vach, W; Beck-Nielsen, H

    2002-01-01

    In this study we examined the relationship between GLUT4 expression at the plasma membrane and muscle fibre size in fibre-typed human muscle fibres by immunocytochemistry and morphometry in order to gain further insight into the regulation of GLUT4 expression. At the site of the plasma membrane......, GLUT4 was more abundantly expressed in slow as compared to fast fibres at the same fibre diameter (p GLUT4 expression increased with increasing fibre radius independently of fibre type (p GLUT4 density at the surface of slow fibres of both diabetic and obese was reduced...... compared to control subjects at the same diameter (p GLUT4 expression (p

  15. Correlation of Utrophin Levels with the Dystrophin Protein Complex and Muscle Fibre Regeneration in Duchenne and Becker Muscular Dystrophy Muscle Biopsies.

    Science.gov (United States)

    Janghra, Narinder; Morgan, Jennifer E; Sewry, Caroline A; Wilson, Francis X; Davies, Kay E; Muntoni, Francesco; Tinsley, Jonathon

    2016-01-01

    Duchenne muscular dystrophy is a severe and currently incurable progressive neuromuscular condition, caused by mutations in the DMD gene that result in the inability to produce dystrophin. Lack of dystrophin leads to loss of muscle fibres and a reduction in muscle mass and function. There is evidence from dystrophin-deficient mouse models that increasing levels of utrophin at the muscle fibre sarcolemma by genetic or pharmacological means significantly reduces the muscular dystrophy pathology. In order to determine the efficacy of utrophin modulators in clinical trials, it is necessary to accurately measure utrophin levels and other biomarkers on a fibre by fibre basis within a biopsy section. Our aim was to develop robust and reproducible staining and imaging protocols to quantify sarcolemmal utrophin levels, sarcolemmal dystrophin complex members and numbers of regenerating fibres within a biopsy section. We quantified sarcolemmal utrophin in mature and regenerating fibres and the percentage of regenerating muscle fibres, in muscle biopsies from Duchenne, the milder Becker muscular dystrophy and controls. Fluorescent immunostaining followed by image analysis was performed to quantify utrophin intensity and β-dystrogylcan and ɣ -sarcoglycan intensity at the sarcolemma. Antibodies to fetal and developmental myosins were used to identify regenerating muscle fibres allowing the accurate calculation of percentage regeneration fibres in the biopsy. Our results indicate that muscle biopsies from Becker muscular dystrophy patients have fewer numbers of regenerating fibres and reduced utrophin intensity compared to muscle biopsies from Duchenne muscular dystrophy patients. Of particular interest, we show for the first time that the percentage of regenerating muscle fibres within the muscle biopsy correlate with the clinical severity of Becker and Duchenne muscular dystrophy patients from whom the biopsy was taken. The ongoing development of these tools to quantify

  16. Analysing the nanoporous structure of aramid fibres

    DEFF Research Database (Denmark)

    Pauw, Brian Richard; Vigild, Martin Etchells; Mortensen, Kell

    2010-01-01

    After consideration of the applicability of classical methods, a novel analysis method for the characterization of fibre void structures is presented, capable of fitting the entire anisotropic two-dimensional scattering pattern to a model of perfectly aligned, polydisperse ellipsoids. It is tested...... for validity against the computed scattering pattern for a simulated nanostructure, after which it is used to fit the scattering from the void structure of commercially available heat-treated poly(p-phenylene terephtalamide) fibre and its as-spun precursor fibre. The application shows a reasonable fit...... scattering on the scattering pattern. The fit to the scattering pattern of as-spun aramid fibre is improved by the introduction of the large scatterers, while the fit to the scattering pattern obtained from the heat-treated fibre improves when an orientation distribution is taken into account...

  17. Mode conversion in magneto photonic crystal fibre

    Science.gov (United States)

    otmani, Hamza; Bouchemat, Mohamed; Hocini, Abdesselam; Boumaza, Touraya; benmerkhi, ahlem

    2017-01-01

    The first concept of an integrated isolator was based on nonreciprocal TE-TM mode conversion, the nonreciprocal coupling between these modes is caused by the Faraday rotation if the magnetization is aligned along the z-axis, parallel to mode propagation. We propose to study this magneto-optical phenomenon, by the simulation of magneto photonic crystal fibre (MPCF), it consists of a periodic triangular lattice of air-holes filled with magnetic fluid which consists of magnetic nanoparticles into a BIG (Bismuth Iron Garnet) fibre. We simulated the influence of gyrotropy and the wavelength, and calculated Faraday rotation and modal birefringence. In this fibre the light is guided by internal total reflection, like classical fibres. However it was shown that they could function on a mode conversion much stronger than conventional fibres.

  18. Microstructure and Mechanical Properties of Aligned Natural Fibre Composites

    DEFF Research Database (Denmark)

    Rask, Morten

    Recently, there has been a great interest in developing and maturing natural fibre composites for structural applications. Natural fibres derived from plants such as flax and hemp have the potential to compete with traditional glass fibres as reinforcements in polymer matrices, due to good specific...... properties (stiffness-to-density ratio). The perspective of using natural fibres is to have a sustainable, biodegradable, CO2-neutral alternative to glass fibres. However, so far, it has not been possible to take full advantage of the natural fibre properties when using them for composite applications...... expected based on tests of single fibres. 3) Compared to continuous glass fibres, natural fibres are relatively short, which makes it difficult to achieve an optimized fibre architecture. 4) Natural fibres are hydrophilic, meaning that they do not bond well with standard polymer matrix systems, most...

  19. Silica hollow spheres with nano-macroholes like diatomaceous earth.

    Science.gov (United States)

    Fujiwara, Masahiro; Shiokawa, Kumi; Sakakura, Ikuko; Nakahara, Yoshiko

    2006-12-01

    Artificial synthesis of hollow cell walls of diatoms is an ultimate target of nanomaterial science. The addition of some water-soluble polymers such as sodium polymethacrylate to a solution of water/oil/water emulsion system, which is an essential step of the simple synthetic procedure of silica hollow spheres (microcapsules), led to the formation of silica hollow spheres with nano-macroholes (>100 nm) in their shell walls, the morphologies of which are analogous to those of diatom earth.

  20. Review of Synthetic Methods to Form Hollow Polymer Nanocapsules

    Energy Technology Data Exchange (ETDEWEB)

    Barker, Madeline T. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-03-13

    Syntactic foams have grown in interest due to the widened range of applications because of their mechanical strength and high damage tolerance. In the past, hollow glass or ceramic particles were used to create the pores. This paper reviews literature focused on the controlled synthesis of hollow polymer spheres with diameters ranging from 100 –200 nm. By using hollow polymer spheres, syntactic foams could reach ultra-low densities.

  1. Pinhole Viewing Strengthens the Hollow-Face Illusion

    OpenAIRE

    Koessler, Trent; Hill, Harold

    2015-01-01

    A hollow (concave) mask appears convex when viewed from beyond a certain distance even when viewed stereoscopically—this is the hollow-face illusion. At close viewing distances, the same mask is seen as hollow even when disparity information is eliminated by monocular viewing. A potential source of nonpictorial, monocular information that favors a veridical percept at close distances is accommodation in conjunction with focus blur. In this article, we used pinhole viewing to minimize this pot...

  2. Array of planar membrane modules for producing hydrogen

    Science.gov (United States)

    Vencill, Thomas R [Albuquerque, NM; Chellappa, Anand S [Albuquerque, NM; Rathod, Shailendra B [Hillsboro, OR

    2012-05-08

    A shared or common environment membrane reactor containing a plurality of planar membrane modules with top and bottom thin foil membranes supported by both an intermediary porous support plate and a central base which has both solid extended members and hollow regions or a hollow region whereby the two sides of the base are in fluid communication. The membrane reactor operates at elevate temperatures for generating hydrogen from hydrogen rich feed fuels.

  3. Computational predictions of the tensile properties of electrospun fibre meshes: effect of fibre diameter and fibre orientation.

    Science.gov (United States)

    Stylianopoulos, Triantafyllos; Bashur, Chris A; Goldstein, Aaron S; Guelcher, Scott A; Barocas, Victor H

    2008-10-01

    The mechanical properties of biomaterial scaffolds are crucial for their efficacy in tissue engineering and regenerative medicine. At the microscopic scale, the scaffold must be sufficiently rigid to support cell adhesion, spreading, and normal extracellular matrix deposition. Concurrently, at the macroscopic scale the scaffold must have mechanical properties that closely match those of the target tissue. The achievement of both goals may be possible by careful control of the scaffold architecture. Recently, electrospinning has emerged as an attractive means to form fused fibre scaffolds for tissue engineering. The diameter and relative orientation of fibres affect cell behaviour, but their impact on the tensile properties of the scaffolds has not been rigorously characterized. To examine the structure-property relationship, electrospun meshes were made from a polyurethane elastomer with different fibre diameters and orientations and mechanically tested to determine the dependence of the elastic modulus on the mesh architecture. Concurrently, a multiscale modelling strategy developed for type I collagen networks was employed to predict the mechanical behaviour of the polyurethane meshes. Experimentally, the measured elastic modulus of the meshes varied from 0.56 to 3.0 MPa depending on fibre diameter and the degree of fibre alignment. Model predictions for tensile loading parallel to fibre orientation agreed well with experimental measurements for a wide range of conditions when a fitted fibre modulus of 18 MPa was used. Although the model predictions were less accurate in transverse loading of anisotropic samples, these results indicate that computational modelling can assist in design of electrospun artificial tissue scaffolds.

  4. Magnetic and Optical Properties of Submicron-Size Hollow Spheres

    Directory of Open Access Journals (Sweden)

    Hirofumi Yoshikawa

    2010-02-01

    Full Text Available Magnetic hollow spheres with a controlled diameter and shell thickness have emerged as an important class of magnetic nanomaterials. The confined hollow geometry and pronouncedly curved surfaces induce unique physical properties different from those of flat thin films and solid counterparts. In this paper, we focus on recent progress on submicron-size spherical hollow magnets (e.g., cobalt- and iron-based materials, and discuss the effects of the hollow shape and the submicron size on magnetic and optical properties.

  5. Demonstration of Raman-based, dispersion-managed VCSEL technology for fibre-to-the-hut application

    Science.gov (United States)

    Rotich Kipnoo, E. K.; Kiboi Boiyo, D.; Isoe, G. M.; Chabata, T. V.; Gamatham, R. R. G.; Leitch, A. W. R.; Gibbon, T. B.

    2017-03-01

    For the first time, we experimentally investigate the use of vertical cavity surface emitting lasers (VCSELs) in the fibre-to-the-home (FTTH) flavour for Africa, known as fibre-to-the-hut. Fibre-to-the-hut is a VCSEL based passive optical network technology designed and optimized for African continent. VCSELs have attracted attention in optical communication due to its vast advantages; low power consumption, relatively cheap costs among others. A 4.25 Gb/s uncooled VCSEL is used in a dispersion managed, Raman assisted network achieving beyond 100 km of error free transmission suited for FTTHut scenario. Energy-efficient high performance VCSEL is modulated using a 27-1 PRBS pattern and the signal transmitted on a G.655 fibre utilizing the minimum attenuation window.

  6. Influence of Cellulosic Fibres on the Physical Properties of Fibre Cement Composites

    Science.gov (United States)

    Hospodarova, V.; Stevulova, N.; Vaclavik, V.; Dvorsky, T.

    2017-10-01

    Nowadays, there are new approaches directing to processing of non-conventional fibre-cement composites for application in the housing construction. Vegetable cellulosic fibres coming from natural resources used as reinforcement in cost-effective and environmental friendly building products are in the spotlight. The applying of natural fibres in cement based composites is narrowly linked to the ecological building sector, where a choice of materials is based on components including recyclable, renewable raw materials and low-resource manufacture techniques. In this paper, two types of cellulosic fibres coming from wood pulp and recycled waste paper with 0.2%; 0.3% and 0.5% of fibre addition into cement mixtures were used. Differences in the physical characteristics (flowability, density, coefficient of thermal conductivity and water absorbability) of 28 days hardened fibre-cement composites are investigated. Addition of cellulosic fibres to cement mixture caused worsening the workability of fresh mixture as well as absorbability of hardened composites due to hydrophilic nature of biomaterial, whereas density and thermal conductivity of manufactured cement based fibre plaster are enhanced. The physical properties of cement plasters based on cellulosic fibres depend on structural, physical characteristics of cellulosic fibres, their nature and processing.

  7. Inhibition of starch absorption by dietary fibre. A comparative study of wheat bran, sugar-beet fibre, and pea fibre

    DEFF Research Database (Denmark)

    Hamberg, O; Rumessen, J J; Gudmand-Høyer, E

    1989-01-01

    The effect of dietary fibre on starch absorption was investigated in 8 healthy subjects. Amounts of starch escaping small-bowel absorption was assessed by comparison of breath H2 excretion after test meals and after lactulose (10g). After ingestion of bread made from 100g of wheat flour increases...... in H2 excretion occurred in all subjects; the calculated fractions of unabsorbed starch ranged from 4% to 17% (median, 8%). Concurrent ingestion of this bread with either wheat bran, sugar-beet fibre, or pea fibre increased the fraction of unabsorbed starch to 12.5% (5-22%) (p less than 0.05), 12.5% (5...

  8. Simultaneous transfer of optical frequency and time over 306 km long-haul optical fibre link

    Science.gov (United States)

    Hucl, Vaclav; Cizek, Martin; Pravdova, Lenka; Rerucha, Simon; Hrabina, Jan; Mikel, Bretislav; Smotlacha, Vladimir; Vojtech, Josef; Lazar, Josef; Cip, Ondrej

    2016-12-01

    Optical fibre links for distributing optical frequencies and time stamps were researched and experimentally tested in the past fifteen years. They have been used mainly for stability comparison of experimental optical clocks. But recent development puts demands on a technology transfer from laboratory experiments to the real industry. The remote calibration of interrogators of Fibre Bragg Grating strain sensory networks is one of important examples. The first step of the adoption the time and frequency broadcasting should be the drop-out free long-term operation of this technology between research laboratories connected via long-haul fibre links. We present a 306 km long-haul optical fibre link between the cities of Prague and Brno in the Czech Republic where a coherent transfer of stable optical frequency and a stable time signal has been firstly demonstrated. The link between ISI CAS Brno and CESNET Prague uses an internet communication fibre where a window of 1540-1546 nm is dedicated for the coherent transfer and 1PPS signal. The link is equipped with 6 bidirectional EDFA amplifiers. The optical frequency standard based on the highly-coherent laser Koheras Adjustik working at 1540.5 nm and stabilized with a saturation absorption spectroscopy technique was used for the coherent wave transfer. The suppression of the Doppler shift induced by the optical fibre was based on an accoustooptical modulator with a servo-loop including a fast PID controller processing the beat-note frequency given by mixing of the Adjustik laser (Brno) and the reflected frequency of this laser from the far end of 306 km long-haul fibre link (Prague). We verified the Doppler shift suppression for the coherent wave with a measuring method analysing the transport delay of the 1PPS signal.

  9. Optical fibre instrumentation for environmental monitoring applications

    Science.gov (United States)

    Whitenett, Gillian; Stewart, George; Atherton, Kathryn; Culshaw, Brian; Johnstone, Walter

    2003-09-01

    We report our research on the development of optical fibre trace gas sensors for environmental applications. We describe the operation of a 64-point fibre-optic methane sensor, which has been installed on a landfill site in Glasgow, UK, where methane is used for power generation as part of the current trend for renewable energy programmes. Although the environmental conditions are harsh, the sensor has performed satisfactorily, detecting methane in the range of ~50 ppm to 100% methane. Another area of our current research is the application of erbium-doped fibre lasers and amplifiers in gas spectroscopy. One system under investigation consists of an all-fibre cavity ring-down loop employing a fibre amplifier for the compensation of loop loss. We have been able to obtain ring-down times as long as 0.2 ms, corresponding to ~1100 pulses in the loop, producing an effective increase in a gas cell length from 5 cm to 55 m. The mode-locked operation of fibre lasers is also under investigation and, using dispersion effects, we demonstrate fine tuning of the wavelength which is important for absorption line scanning, with a typical tuning rate of ~0.014 nm kHz-1 at the third harmonic, closely matching the theoretical predictions. Techniques for extending fibre laser systems to form multi-point, multi-species gas sensors are explored.

  10. Fibre intake and laryngeal cancer risk.

    Science.gov (United States)

    Pelucchi, C; Talamini, R; Levi, F; Bosetti, C; La Vecchia, C; Negri, E; Parpinel, M; Franceschi, S

    2003-01-01

    Consumption of vegetables, fruit and whole grain cereals has been inversely related to laryngeal cancer risk. Among the potential protective agents found in these foods, information on dietary fibres and laryngeal cancer risk are scanty. A multi-centric, hospital-based case-control study was conducted on 527 patients with squamous-cell carcinoma of the larynx and 1,297 non-neoplastic controls. Cases and controls, frequency matched by age, sex and study centre, were interviewed using a validated food frequency questionnaire. Compared with the lowest quintile of fibre intake, the odds ratios (ORs) for the highest quintile were 0.3 [95% confidence interval (CI) 0.2-0.4] for total fibre, 0.3 (95% CI 0.2-0.5) for soluble non-cellulose polysaccharides (NCP) and for total insoluble fibre, including cellulose (OR = 0.3, 95% CI 0.2-0.4) and insoluble NCP (OR = 0.4, 95% CI 0.3-0.7). The ORs were 0.2 (95% CI 0.1-0.4) for fibre from vegetables, 0.5 (95% CI 0.3-0.7) from fruit and 1.1 (95% CI 0.6-1.9) from grains. The inverse association observed was similar among different subsites of laryngeal cancer, and consistent across strata of various covariates. This study found a strong inverse association between fibre intake and laryngeal cancer risk, which points to fibre as one of the beneficial components of vegetables and fruit.

  11. Comparison of two novel approaches to model fibre reinforced concrete

    NARCIS (Netherlands)

    Radtke, F.K.F.; Simone, A.; Sluys, L.J.

    2009-01-01

    We present two approaches to model fibre reinforced concrete. In both approaches, discrete fibre distributions and the behaviour of the fibre-matrix interface are explicitly considered. One approach employs the reaction forces from fibre to matrix while the other is based on the partition of unity

  12. Bragg gratings in index-guiding photonic crystal fibres

    DEFF Research Database (Denmark)

    Riishede, Jesper; Hougaard, Kristian G.; Libori, S.E. Barkou

    2002-01-01

    A numerical investigation of coupling coefficients of Bragg-gratings in index-guiding photonic crystal fibres is presented. It is shown that index-guiding photonic crystal fibres have larger coupling coefficients for fibres with small core areas than step-index fibres....

  13. Effect of Moisture on Natural Fibre Reinforced Plastics.

    African Journals Online (AJOL)

    2016-12-01

    Dec 1, 2016 ... which include bagasse, cereal straw, corn stalk, cotton stalk, banana fibres, rice husk / rice straw [4]. The renewed interest resulted in new ways of natural fibre modifications and use and brought them to be superior to synthetic fibres. Composites (reinforced with natural fibres) – the wonder material, with ...

  14. Effects of fibre content on mechanical properties and fracture ...

    Indian Academy of Sciences (India)

    Administrator

    Institute for Advanced Ceramics, Harbin Institute of Technology, Harbin 150001, People's Republic of China. MS received 2 ... short carbon fibres have a great strengthening and toughening effect at low volume percentages of fibres (3⋅5 and 4⋅5 vol. .... to fibre breakage or damage, which has a negative effect on short fibre ...

  15. Investigation on effect of fibre hybridization and orientation on ...

    Indian Academy of Sciences (India)

    ... and neem fibres withinclined orientation (45 ∘ ) have better mechanical properties when compared with other types of composites. In addition, morphological analysis is carried out using scanning electron microscope to know the fibre distribution, fibre pull out, fibre breakage and crack propagation on tested composites.

  16. Influence of fibre-surface treatment on structural, thermal and ...

    Indian Academy of Sciences (India)

    Administrator

    were prepared with treated and untreated jute fibre (15 wt%) reinforced unsaturated polyester (UPE). .... fibres whereas W2 was the weight of dry fibres after being .... 2.5e Thermal analysis of fibre: DSC measurements were performed using a (TA Instrument, USA, Model No. Q10) thermal analyser. A heating rate of 10 o.

  17. Dietary fibre: new frontiers for food and health

    National Research Council Canada - National Science Library

    Kamp, J. W. van der

    2010-01-01

    ... papers of the Dietary fibre analysis workshop and the HEALTHGRAIN Symposium Cereal grain fibre and health , both held in conjunction with DF09. This book is titled Dietary fibre- new frontiers for food and health . With the adoption - after decades of debate - of almost identical definitions of dietary fibre by Codex Alimentarius and the European Un...

  18. Assessment of Fibre Characteristics and Suitability of Maize Husk ...

    African Journals Online (AJOL)

    Maize husk and stalk were assessed for their fibre characteristics and suitability for pulp and paper production. Fifteen (15) fibres were randomly selected and measured from each representative sample. It was observed that fibre length of maize husk was 1.37mm and that of maize stalk was 1.52mm. The fibre diameter (D) ...

  19. Patients with multiple sclerosis demonstrate reduced subbasal corneal nerve fibre density.

    Science.gov (United States)

    Mikolajczak, Janine; Zimmermann, Hanna; Kheirkhah, Ahmad; Kadas, Ella Maria; Oberwahrenbrock, Timm; Muller, Rodrigo; Ren, Aiai; Kuchling, Joseph; Dietze, Holger; Prüss, Harald; Paul, Friedemann; Hamrah, Pedram; Brandt, Alexander U

    2017-12-01

    Many studies in multiple sclerosis (MS) have investigated the retina. Little, however, is known about the effect of MS on the cornea, which is innervated by the trigeminal nerve. It is the site of neural-immune interaction with local dendritic cells reacting in response to environmental stimuli. This study aims to investigate the effect of MS on corneal nerve fibres and dendritic cells in the subbasal nerve plexus using in vivo confocal microscopy (IVCM). We measured the corneal nerve fibre and dendritic cell density in 26 MS patients and matched healthy controls using a Heidelberg Retina Tomograph with cornea module. Disease severity was assessed with the Multiple Sclerosis Functional Composite, Expanded Disability Status Scale, visual acuity and retinal optical coherence tomography. We observed significant reduction in total corneal nerve fibre density in MS patients compared to controls. Dendritic cell density was similar in both groups. Reduced total nerve fibre density was associated with worse clinical severity but not with previous clinical trigeminal symptoms, retinal neuro-axonal damage, visual acuity or disease duration. Corneal nerve fibre density is a promising new imaging marker for the assessment of disease severity in MS and should be investigated further.

  20. Electrochemical engineering of hollow nanoarchitectures: pulse/step anodization (Si, Al, Ti) and their applications.

    Science.gov (United States)

    Wang, Kaiying; Liu, Guohua; Hoivik, Nils; Johannessen, Erik; Jakobsen, Henrik

    2014-03-07

    Hollow nanoarchitectured materials with straight channels play a crucial role in the fields of renewable energy, environment and biotechnology due to their one-dimensional morphology and extraordinary properties. The current challenge is the difficulty on tailoring hollow nanoarchitectures with well-controlled morphology at a relatively low cost. As a conventional technique, electrochemistry exhibits its unique advantage on machining nanostructures. In this review, we present the progress of electrochemistry as a valuable tool in construction of novel hollow nanoarchitectures through pulse/step anodization, such as surface pre-texturing, modulated, branched and multilayered pore architectures, and free-standing membranes. Basic principles for electrochemical engineering of mono- or multi-ordered nanostructures as well as free-standing membranes are extracted from specific examples (i.e. porous silicon, aluminum and titanium oxide). The potential of such nanoarchitectures are further demonstrated for the applications of photovoltaics, water splitting, organic degradation, nanostructure templates, biosensors and drug release. The electrochemical techniques provide a powerful approach to produce nanostructures with morphological complexity, which could have far-reaching implications in the design of future nanoscale systems.

  1. Minimally invasive insulin delivery in subjects with type 1 diabetes using hollow microneedles.

    Science.gov (United States)

    Gupta, Jyoti; Felner, Eric I; Prausnitz, Mark R

    2009-06-01

    Microneedles have previously been used to deliver insulin to animal models, but not in human subjects. This study tested the hypothesis that hollow microneedles can deliver insulin to modulate blood glucose levels in subjects with type 1 diabetes in a minimally invasive manner. This study was carried out in two adults with type 1 diabetes and evaluated bolus delivery of lispro insulin using a hollow microneedle compared to a catheter infusion set (9 mm). The study first determined the minimum insulin delivery depth by administering insulin from microneedles inserted 1, 3.5, and 5 mm into the skin of fasting subjects and then assessed the efficacy of insulin delivery from microneedles inserted 1 mm into the skin to reduce postprandial glucose levels. Blood samples were periodically assayed for plasma free insulin and plasma glucose levels for up to 3.5 h. The first phase of the study indicated that microneedles inserted at the shallowest depth of 1 mm within the skin led to rapid insulin absorption and reduction in glucose levels. Bolus insulin delivery followed by consumption of a standardized meal in the second phase revealed that microneedles were effective in reducing postprandial glucose levels. Subjects reported no pain from microneedle treatments, and there were no adverse events. This study provides the first proof of concept that hollow microneedles can effectively deliver bolus insulin to type 1 diabetes subjects in a minimally invasive manner.

  2. Improved performance of gravity-driven membrane filtration for seawater pretreatment: Implications of membrane module configuration.

    Science.gov (United States)

    Wu, Bing; Christen, Tino; Tan, Hwee Sin; Hochstrasser, Florian; Suwarno, Stanislaus Raditya; Liu, Xin; Chong, Tzyy Haur; Burkhardt, Michael; Pronk, Wouter; Fane, Anthony G

    2017-05-01

    As a low energy and chemical free process, gravity-driven membrane (GDM) filtration has shown a potential for seawater pretreatment in our previous studies. In this study, a pilot submerged GDM reactor (effective volume of 720 L) was operated over 250 days and the permeate flux stabilized at 18.6 ± 1.4 L/m2h at a hydrostatic pressure of 40 mbar. This flux was higher than those in the lab-scale GDM reactor (16.3 ± 0.2 L/m2h; effective volume of 8.4 L) and in the filtration cell system (2.7 ± 0.6 L/m2h; feed side volume of 0.0046 L) when the same flat sheet membrane was used. Interestingly, when the filtration cell was submerged into the GDM reactor, the flux (17.2 L/m2h) was comparable to the submerged membrane module. Analysis of cake layer morphology and foulant properties indicated that a thicker but more porous cake layer with less accumulation of organic substances (biopolymers and humics) contributed to the improved permeate flux. This phenomenon was possibly associated with longer residence time of organic substances and sufficient space for the growth, predation, and movement of the eukaryotes in the GDM reactor. In addition, the permeate flux of the submerged hollow fibre membrane increased with decreasing packing density. It is thought that the movement of large-sized eukaryotes could be limited when the space between hollow fibres was reduced. In terms of pretreatment, the GDM systems effectively removed turbidity, viable cells, and transparent exopolymer particles from the feed seawater. Importantly, extending the reactor operation time produced a permeate with less assimilable organic carbon and biopolymers. Thus, the superior quality of the GDM permeate has the potential to alleviate subsequent reverse osmosis membrane fouling for seawater treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Hollow fiber membrane contactors for CO2 capture: modeling and up-scaling to CO2 capture for an 800 MWe coal power station

    NARCIS (Netherlands)

    Kimball, E.; Al-Azki, A.; Gomez, A.; Goetheer, E.L.V.; Booth, N.; Adams, D.; Ferre, D.

    2014-01-01

    A techno-economic analysis was completed to compare the use of Hollow Fiber Membrane Modules (HFMM) with the more conventional structured packing columns as the absorber in amine-based CO2capture systems for power plants. In order to simulate the operation of industrial scale HFMMsystems, a

  4. Fibre mapping--a case study.

    Science.gov (United States)

    Coyle, T; Larkin, A; Smith, K; Mayo, S; Chan, A; Hunt, N

    2004-01-01

    Fibre mapping, more commonly known as one-to-one taping, was developed in Germany approximately twenty years ago. The technique facilitates the distribution of fibres on a surface to be recorded. The impact of this technique on the investigation of serious crime has been reported in the European Fibre Group on several occasions. This paper represents a case study of the application of the technique. It is believed to be the first time that this technique has been successfully applied in the United Kingdom.

  5. Dopant diffusion during optical fibre drawing.

    Science.gov (United States)

    Lyytikainen, K; Huntington, S; Carter, A; McNamara, P; Fleming, S; Abramczyk, J; Kaplin, I; Schötz, G

    2004-03-22

    Diffusion of Ge and F was studied during drawing of silica optical fibres. Preforms were drawn using various draw conditions and fibres analysed using the etching and Atomic Force Microscope (AFM) technique. The results were confirmed by comparison with fibre Refractive Index Profiles (RIP). Both Ge and F were found to diffuse at high temperature, 2100 degrees C, and low draw speed, 10m/min. Diffusion simulations showed that most diffusion occurred in the neck-down region. The draw temperature and preform feed rate had a comparable effect on diffusion, whereas preform diameter did not significantly affect the diffusion.

  6. A device to characterize optical fibres

    CERN Document Server

    Bosi, F; Cavasinni, V; Costanzo, D; Del Prete, T; Flaminio, Vincenzo; Mazzoni, E; Roda, C; Usai, G L; Vasilev, A V

    2002-01-01

    ATLAS is a general purpose experiment approved for the LHC collider at CERN. An important component of the detector is the central hadronic calorimeter; for its construction more than 600,000 Wave Length Shifting (WLS) fibres (corresponding to a total length of 1,120 Km) have been used. We have built and put into operation a dedicated instrument for the measurement of light yield and attenuation length over groups of 20 fibres at a time. The overall accuracy achieved in the measurement of light yield (attenuation length) is 1.5% (3%). We also report the results obtained using this method in the quality control of a large sample of fibres.

  7. Linear and Non-linear Analysis of Fibre Reinforced Plastic Bridge Deck due to Vehicle Loads

    Science.gov (United States)

    Ray, Chaitali; Mandal, Bibekananda

    2015-06-01

    The present work deals with linear and nonlinear static analysis of fibre reinforced plastics composite bridge deck structures using the finite element method. The nonlinear static analysis has been carried out considering geometric nonlinearity. The analysis of bridge deck has been carried out under vehicle load as specified by IRC Class B wheel load classification. The formulation has been carried out using the finite element software package ANSYS 14.0 and the SHELL281 element is used to model the bridge deck. The bridge deck has also been modeled as a plate stiffened with closely spaced hollow box sections and a computer code is developed based on this formulation. The results obtained from the present formulation are compared with those available in the published literature. A parametric study on the stiffened bridge deck has also been carried out with varying dimensions of the stiffeners under vehicle loads.

  8. Methodology for characterisation of glass fibre composite architecture

    DEFF Research Database (Denmark)

    Hansen, Jens Zangenberg; Larsen, J.B.; Østergaard, R.C.

    2012-01-01

    The present study outlines a methodology for microstructural characterisation of fibre reinforced composites containing circular fibres. Digital micrographs of polished cross-sections are used as input to a numerical image processing tool that determines spatial mapping and radii detection...... of the fibres. The information is used for different analyses to investigate and characterise the fibre architecture. As an example, the methodology is applied to glass fibre reinforced composites with varying fibre contents. The different fibre volume fractions (FVFs) affect the number of contact points per...... fibre, the communal fibre distance and the local FVF. The fibre diameter distribution and packing pattern remain somewhat similar for the considered materials. The methodology is a step towards a better understanding of the composite microstructure and can be used to evaluate the interconnection between...

  9. Spectral Clustering of Hermean craters hollows

    Science.gov (United States)

    Lucchetti, Alice; Pajola, Maurizio; Cremonese, Gabriele; Carli, Cristian; Marzo, Giuseppe; Roush, Ted

    2017-04-01

    The Mercury Dual Imaging System (MDIS, Hawkins et al., 2007) onboard NASA MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) spacecraft, provided high-resolution images of "hollows", i.e. shallow, irregular, rimless, flat-floored depressions with bright interiors and halos, often found on crater walls, rims, floors and central peaks (Blewett et al., 2011, 2013). The formation mechanism of these features was suggested to be related to the depletion of subsurface volatiles (Blewett et al., 2011, Vaughan et al., 2012). To understand the hollows' mineralogical composition, which can provide new insights on Mercury's surface characterization, we applied a spectral clustering method to different craters where hollows are present. We chose, as first test case, the 20 km wide Dominici crater due to previous multiple spectral detection (Vilas et al., 2016). We used the MDIS WAC dataset covering Dominici crater with a scale of 935 m/pixel through eight filters, ranging from 0.433 to 0.996 μm. First, the images have been photometrically corrected using the Hapke parameters (Hapke et al., 2002) derived in Domingue et al. (2015). We then applied a statistical clustering over the entire dataset based on a K-means partitioning algorithm (Marzo et al., 2006). This approach was developed and evaluated by Marzo et al. (2006, 2008, 2009) and makes use of the Calinski and Harabasz criterion (Calinski, T., Harabasz, J., 1974) to identify the intrinsically natural number of clusters, making the process unsupervised. The natural number of ten clusters was identified and spectrally separates the Dominici surrounding terrains from its interior, as well as the two hollows from their edges. The units located on the brightest part of the south wall/rim of Dominici crater clearly present a wide absorption band between 0.558 and 0.828 μm. Hollows surrounding terrains typically present a red slope in the VNIR with a possible weak absorption band centered at 0.748

  10. Polyoxadiazole hollow fibers for produced water treatment by direct contact membrane distillation

    KAUST Repository

    Xu, Jingli

    2018-01-08

    Treatment of produced water in the petroleum industry has been a challenge worldwide. In this study, we evaluated the use of direct contact membrane distillation (DCMD) for this purpose, removing oil and dissolved elements and supplying clean water from waste. We synthesized fluorinated polyoxadiazole, a highly hydrophobic polymer, to fabricate hollow fiber membranes, which were optimized and tested for simulated produced water and real produced water treatment. The process performance was investigated under different operating parameters, such as feed temperature, feed flow velocity and length of the membrane module for 4 days. The results indicate that by increasing feed temperature and feed flow rate the vapor flux increases. The flux decreased with increasing the length of the module due to the decrease of the driving force along the module. The fouling behavior, which corresponds to flux decline and cleaning efficiency of the membrane, was studied. The performance of the fabricated hollow fiber membranes was demonstrated for the treatment of produced water, complying with the industrial reuse and discharge limits.

  11. Hollow-Fiber Spacesuit Water Membrane Evaporator

    Science.gov (United States)

    Bue, Grant; Trevino, Luis; Tsioulos, Gus; Mitchell, Keith; Settles, Joseph

    2013-01-01

    The hollow-fiber spacesuit water membrane evaporator (HoFi SWME) is being developed to perform the thermal control function for advanced spacesuits and spacecraft to take advantage of recent advances in micropore membrane technology in providing a robust, heat-rejection device that is less sensitive to contamination than is the sublimator. After recent contamination tests, a commercial-off-the-shelf (COTS) micro porous hollow-fiber membrane was selected for prototype development as the most suitable candidate among commercial hollow-fiber evaporator alternatives. An innovative design that grouped the fiber layers into stacks, which were separated by small spaces and packaged into a cylindrical shape, was developed into a full-scale prototype for the spacesuit application. Vacuum chamber testing has been performed to characterize heat rejection as a function of inlet water temperature and water vapor back-pressure, and to show contamination resistance to the constituents expected to be found in potable water produced by the wastewater reclamation distillation processes. Other tests showed tolerance to freezing and suitability to reject heat in a Mars pressure environment. In summary, HoFi SWME is a lightweight, compact evaporator for heat rejection in the spacesuit that is robust, contamination- insensitive, freeze-tolerant, and able to reject the required heat of spacewalks in microgravity, lunar, and Martian environments. The HoFi is packaged to reject 810 W of heat through 800 hours of use in a vacuum environment, and 370 W in a Mars environment. The device also eliminates free gas and dissolved gas from the coolant loop.

  12. Co-Flow Hollow Cathode Technology

    Science.gov (United States)

    Hofer, Richard R.; Goebel, Dan M.

    2011-01-01

    Hall thrusters utilize identical hollow cathode technology as ion thrusters, yet must operate at much higher mass flow rates in order to efficiently couple to the bulk plasma discharge. Higher flow rates are necessary in order to provide enough neutral collisions to transport electrons across magnetic fields so that they can reach the discharge. This higher flow rate, however, has potential life-limiting implications for the operation of the cathode. A solution to the problem involves splitting the mass flow into the hollow cathode into two streams, the internal and external flows. The internal flow is fixed and set such that the neutral pressure in the cathode allows for a high utilization of the emitter surface area. The external flow is variable depending on the flow rate through the anode of the Hall thruster, but also has a minimum in order to suppress high-energy ion generation. In the co-flow hollow cathode, the cathode assembly is mounted on thruster centerline, inside the inner magnetic core of the thruster. An annular gas plenum is placed at the base of the cathode and propellant is fed throughout to produce an azimuthally symmetric flow of gas that evenly expands around the cathode keeper. This configuration maximizes propellant utilization and is not subject to erosion processes. External gas feeds have been considered in the past for ion thruster applications, but usually in the context of eliminating high energy ion production. This approach is adapted specifically for the Hall thruster and exploits the geometry of a Hall thruster to feed and focus the external flow without introducing significant new complexity to the thruster design.

  13. DESIGN OF COMPOSITION OF CONCRETE USING POLYPROPYLENE FIBRE REINFORCEMENT

    OpenAIRE

    Dang Van Thanh1,*, Vu Hoang Hiep2, Nguyen Van Bac1, Hoang Gia Duong1

    2016-01-01

    Fibre-reinforced concrete is an emerging trend that delivers new materials with high quality for construction. Polyporpylene fibre, an organic textile, has high potential to be used for reinforcing concrete, but there has been little research conducted into using this fibre for concrete reinforcement worldwide and no research work on this fibre reinforced concrete has been published in Vietnam. Thereofore, researchinginto Polyporylene fibre reinforced concrete to establish fundamental underst...

  14. All-fibre devices for modern telecommunication systems

    OpenAIRE

    Petropoulos, P.

    2004-01-01

    Optical fibre technology enables the implementation of several key operations that increase the functionality of the optical layer in modern communication networks. Thus, optical fibres are used not only for transferring data signals from one point to the next, but also to implement sophisticated devices such as filters, amplifiers, or even ultrafast all-optical switches. This talk will review some of the most enabling fibre-based devices, such as the erbium-doped fibre amplifier and the fibr...

  15. Individual fibre segmentation from 3D X-ray computed tomography for characterising the fibre orientation in unidirectional composite materials

    DEFF Research Database (Denmark)

    Emerson, Monica Jane; Jespersen, Kristine Munk; Dahl, Anders Bjorholm

    2017-01-01

    The aim of this paper is to characterise the fibre orientation in unidirectional fibre reinforced polymers, namely glass and carbon fibre composites. The compression strength of the composite is related to the orientation of the fibres. Thus the orientation is essential when designing materials...... of composites with high fibre volume fraction. From the individual fibre orientations, it is possible to obtain results which are independent of the scanning quality. The compression strength for both composites is estimated from the average fibre orientations and is found to be of the same order of magnitude...

  16. Hollow Electron Lens Simulation for the SPS

    CERN Document Server

    Previtali, V; Stancari, G; Valishev, A

    2013-01-01

    The hardware of the Tevatron hollow electron lens, which has been used in the past for collimation purposes, is presently available. Possible applications of similar devices in the LHC are under evaluation, but a realistic date for installation of electron lenses in the LHC would be not earlier than the machine shutdown scheduled for 2018. We investigated the possibility of beam tests with the available hardware in the meantime in the SPS. This article aims to answer this question by presenting the results of dedicated numerical simulations

  17. Casting of particle-based hollow shapes

    Science.gov (United States)

    Menchhofer, Paul

    1995-01-01

    A method for the production of hollow articles made of a particle-based material; e.g., ceramics and sintered metals. In accordance with one aspect of the invention, a thermally settable slurry containing a relatively high concentration of the particles is coated onto a prewarmed continuous surface in a relatively thin layer so that the slurry is substantially uniformly coated on the surface. The heat of the prewarmed surface conducts to the slurry to initiate a reaction which causes the slurry to set or harden in a shape conforming to the surface. The hardened configurations may then be sintered to consolidate the particles and provide a high density product.

  18. Shrinkage Behaviour of Fibre Reinforced Concrete with Recycled Tyre Polymer Fibres

    Directory of Open Access Journals (Sweden)

    Marijana Serdar

    2015-01-01

    Full Text Available Different types of fibres are often used in concrete to prevent microcracking due to shrinkage, and polypropylene fibres are among the most often used ones. If not prevented, microcracks can lead to the development of larger cracks as drying shrinkage occurs, enabling penetration of aggressive substances from the environment and reducing durability of concrete structures. The hypothesis of the present research is that polypropylene fibres, used in concrete for controlling formation of microcracks due to shrinkage, can be replaced with recycled polymer fibres obtained from end-of-life tyres. To test the hypothesis, concrete mixtures containing polypropylene fibres and recycled tyre polymer fibres were prepared and tested. Experimental programme focused on autogenous, free, and restrained shrinkage. It was shown that PP fibres can be substituted with higher amount of recycled tyre polymer fibres obtaining concrete with similar shrinkage behaviour. The results indicate promising possibilities of using recycled tyre polymer fibres in concrete products. At the same time, such applications would contribute to solving the problem of waste tyre disposal.

  19. ELASTICITY of SHORT FIBRE REINFORCED POLYAMIDE: MORPHOLOGICAL AND NUMERICAl ANALYSIS OF FIBRE ORIENTATION EFFECTS

    Directory of Open Access Journals (Sweden)

    Francesca Cosmi

    2010-10-01

    Full Text Available The fatigue behaviour of injection moulded short fibre reinforced polymers depends upon fibre orientation, as shown in experiments conducted with notched specimens injected through different injection gates. The different fatigue behaviour is mainly related to the different local elastic properties, as determined by the different fibre orientation patterns, resulting into different strain distributions. In order to quantify the relationship between fibre orientation and elastic constants, the Cell Method was applied to volumes extracted from the specimens, reconstructed by micro-tomography.

  20. Porous-wall hollow glass microspheres as carriers for biomolecules

    Science.gov (United States)

    Li, Shuyi; Dynan, William S; Wicks, George; Serkiz, Steven

    2013-09-17

    The present invention includes compositions of porous-wall hollow glass microspheres and one or more biomolecules, wherein the one or more biomolecules are positioned within a void location within the hollow glass microsphere, and the use of such compositions for the diagnostic and/or therapeutic delivery of biomolecules.

  1. Fabrication of Closed Hollow Bulb Obturator Using Thermoplastic Resin Material

    Directory of Open Access Journals (Sweden)

    Bidhan Shrestha

    2015-01-01

    Full Text Available Purpose. Closed hollow bulb obturators are used for the rehabilitation of postmaxillectomy patients. However, the time consuming process, complexity of fabrication, water leakage, and discoloration are notable disadvantages of this technique. This paper describes a clinical report of fabricating closed hollow bulb obturator using a single flask and one time processing method for an acquired maxillary defect. Hard thermoplastic resin sheet has been used for the fabrication of hollow bulb part of the obturator. Method. After fabrication of master cast conventionally, bulb and lid part of the defect were formed separately and joined by autopolymerizing acrylic resin to form one sized smaller hollow body. During packing procedure, the defect area was loaded with heat polymerizing acrylic resin and then previously fabricated smaller hollow body was adapted over it. The whole area was then loaded with heat cure acrylic. Further processes were carried out conventionally. Conclusion. This technique uses single flask which reduces laboratory time and makes the procedure simple. The thickness of hollow bulb can be controlled and light weight closed hollow bulb prosthesis can be fabricated. It also minimizes the disadvantages of closed hollow bulb obturator such as water leakage, bacterial infection, and discoloration.

  2. optimizing compression zone of flanged hollow cored concrete ...

    African Journals Online (AJOL)

    eobe

    effective flange width and the hollow core position in the compression zone of a plain concrete beam with a point loaded at .... OPTIMIZING COMPRESSION ZONE OF FLANGED HOLLOW CORED CONCRETE BEAMS USING MOMENT OF INERTIA THEORY, ... chi-square test, a correction factor was obtained using.

  3. Outer-selective pressure-retarded osmosis hollow fiber membranes from vacuum-assisted interfacial polymerization for osmotic power generation

    KAUST Repository

    Sun, Shipeng

    2013-11-19

    In this paper, we report the technical breakthroughs to synthesize outer-selective thin-film composite (TFC) hollow fiber membranes, which is in an urgent need for osmotic power generation with the pressure-retarded osmosis (PRO) process. In the first step, a defect-free thin-film composite membrane module is achieved by vacuum-assisted interfacial polymerization. The PRO performance is further enhanced by optimizing the support in terms of pore size and mechanical strength and the TFC layer with polydopamine coating and molecular engineering of the interfacial polymerization solution. The newly developed membranes can stand over 20 bar with a peak power density of 7.63 W/m2, which is equivalent to 13.72 W/m2 of its inner-selective hollow fiber counterpart with the same module size, packing density, and fiber dimensions. The study may provide insightful guidelines for optimizing the interfacial polymerization procedures and scaling up of the outer-selective TFC hollow fiber membrane modules for PRO power generation. © 2013 American Chemical Society.

  4. Outer-selective pressure-retarded osmosis hollow fiber membranes from vacuum-assisted interfacial polymerization for osmotic power generation.

    Science.gov (United States)

    Sun, Shi-Peng; Chung, Tai-Shung

    2013-11-19

    In this paper, we report the technical breakthroughs to synthesize outer-selective thin-film composite (TFC) hollow fiber membranes, which is in an urgent need for osmotic power generation with the pressure-retarded osmosis (PRO) process. In the first step, a defect-free thin-film composite membrane module is achieved by vacuum-assisted interfacial polymerization. The PRO performance is further enhanced by optimizing the support in terms of pore size and mechanical strength and the TFC layer with polydopamine coating and molecular engineering of the interfacial polymerization solution. The newly developed membranes can stand over 20 bar with a peak power density of 7.63 W/m(2), which is equivalent to 13.72 W/m(2) of its inner-selective hollow fiber counterpart with the same module size, packing density, and fiber dimensions. The study may provide insightful guidelines for optimizing the interfacial polymerization procedures and scaling up of the outer-selective TFC hollow fiber membrane modules for PRO power generation.

  5. Thermally induced structural changes in Nomex fibres

    Indian Academy of Sciences (India)

    ray crystallinity, weight loss and deterioration in tensile characteristics. Surface damages in the form of longitudinal openings, holes, material deposits etc have also been observed. Based on the data from thermally exposed fibres, the time ...

  6. Radiation-resistant fibre for particle accelerator

    CERN Multimedia

    2007-01-01

    "Radiation-resistant optical fibre is being used by CERN, the European Laboratory for Particle Physics, in the world's largest particle accelerator, the Large Hadron Collider (LHC) near Geneva." (1 page)

  7. Optical fibres bringing the LHC into focus

    CERN Multimedia

    2003-01-01

    New components are being added to CERN's optical fibre network, which will transport the torrents of data produced by the LHC. 1500 kilometres of cables will be installed in the tunnels and at ground level.

  8. Central Tracking Detector Based on Scintillating Fibres

    CERN Multimedia

    2002-01-01

    Scintillating fibres form a reasonable compromise for central tracking detectors in terms of price, resolution, response time, occupancy and heat production. \\\\ \\\\ New fluorescents with large Stokes shifts have been produced, capable of working without wavelength shifters. Coherent multibundles have been developed to achieve high packing fractions. Small segments of tracker shell have been assembled and beam tests have confirmed expectations on spatial resolution. An opto-electronic delay line has been designed to delay the track patterns and enable coincidences with a first level trigger. Replacement of the conventional phosphor screen anode with a Si pixel chip is achieved. This tube is called ISPA-tube and has already been operated in beam tests with a scintillating fibres tracker. \\\\ \\\\ The aim of the proposal is to improve hit densities for small diameter fibres by increasing the fraction of trapped light, by reducing absorption and reflection losses, by reflecting light at the free fibre end, and by inc...

  9. Creep Strength of Discontinuous Fibre Composites

    DEFF Research Database (Denmark)

    Pedersen, Ole Bøcker

    1974-01-01

    A unidirectional, discontinuous fibre composite is considered under conditions of steady state creep in the direction of reinforcement. The composite consists of noncreeping, discontinuous, perfectly aligned, uniformly distributed fibres which are perfectly bonded to a matrix obeying a power...... relation between stress and strain rate. Expressions for the interface stress, the creep velocity profile adjacent to the fibres and the creep strength of the composite are derived. Previous results for the creep strength, sc = aVfs0 ( \\frac[( Î )\\dot] [( Î )\\dot] 0 )1/nr1 + 1/n c=Vf001n1+1n in which[( Î...... )\\dot] is the composite creep rate,V f is the fibre volume fraction,sgr 0,epsi 0 andn are the constants in the matrix creep law. The creep strength coefficient agr is found to be very weakly dependent onV f and practically independent ofn whenn is greater than about 6....

  10. Plant fibre composites - porosity and stiffness

    DEFF Research Database (Denmark)

    Madsen, Bo; Thygesen, Anders; Lilholt, Hans

    2009-01-01

    Plant fibre composites contain typically a relatively large amount of porosity which influences their performance. A model, based on a modified rule of mixtures, is presented to include the influence of porosity on the composite stiffness. The model integrates the volumetric composition...... of the composites with their mechanical properties. The fibre weight fraction is used as an independent parameter to calculate the complete volumetric composition. A maximum obtainable stiffness of the composites is calculated at a certain transition fibre weight fraction, which is characterised by a best possible...... combination of high fibre volume fraction and low porosity. The model is validated with experimental data from the literature on several types of composites. A stiffness diagram is presented to demonstrate that the calculations can be used for tailoring and design of composites with a given profile...

  11. Growth of hollow cell spheroids in microbead templated chambers.

    Science.gov (United States)

    Wang, Eddie; Wang, Dong; Geng, Andrew; Seo, Richard; Gong, Xiaohua

    2017-10-01

    Cells form hollow, spheroidal structures during the development of many tissues, including the ocular lens, inner ear, and many glands. Therefore, techniques for in vitro formation of hollow spheroids are valued for studying developmental and disease processes. Current in vitro methods require cells to self-organize into hollow morphologies; we explored an alternative strategy based on cell growth in predefined, spherical scaffolds. Our method uses sacrificial, gelatin microbeads to simultaneously template spherical chambers within a hydrogel and deliver cells into the chambers. We use mouse lens epithelial cells to demonstrate that cells can populate the internal surfaces of the chambers within a week to create numerous hollow spheroids. The platform supports manipulation of matrix mechanics, curvature, and biochemical composition to mimic in vivo microenvironments. It also provides a starting point for engineering organoids of tissues that develop from hollow spheroids. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. A 200 W Hall thruster with hollow indented anode

    Science.gov (United States)

    Ding, Yongjie; Sun, Hezhi; Wei, Liqiu; Li, Peng; Su, Hongbo; Peng, Wuji; Yu, Daren

    2017-10-01

    A hollow indented anode is proposed for increasing the neutral gas density in a discharge channel, in order to improve the performance of the thruster. The experimental results show that a hollow indented anode structure can effectively improve the performance, compared to a hollow straight anode under similar operating conditions, in terms of thrust, propellant utilization, ionization rate, and anode efficiency. Furthermore, simulations show that the indented anode can effectively increase the neutral gas density in a discharge channel and on the centerline of the channel, compared to a hollow straight anode. In addition, it can increase the ionization rate in the channel and the pre-ionization in the anode. Therefore, the hollow indented anode could be considered as an important design idea for improving thruster performance.

  13. Hollow fiber bioreactor technology for tissue engineering applications.

    Science.gov (United States)

    Eghbali, Hadis; Nava, Michele M; Mohebbi-Kalhori, Davod; Raimondi, Manuela T

    2016-01-01

    Hollow fiber bioreactors are the focus of scientific research aiming to mimic physiological vascular networks and engineer organs and tissues in vitro. The reason for this lies in the interesting features of this bioreactor type, including excellent mass transport properties. Indeed, hollow fiber bioreactors allow limitations to be overcome in nutrient transport by diffusion, which is often an obstacle to engineer sizable constructs in vitro. This work reviews the existing literature relevant to hollow fiber bioreactors in organ and tissue engineering applications. To this purpose, we first classify the hollow fiber bioreactors into 2 categories: cylindrical and rectangular. For each category, we summarize their main applications both at the tissue and at the organ level, focusing on experimental models and computational studies as predictive tools for designing innovative, dynamic culture systems. Finally, we discuss future perspectives on hollow fiber bioreactors as in vitro models for tissue and organ engineering applications.

  14. Self-templated chemically stable hollow spherical covalent organic framework

    Science.gov (United States)

    Kandambeth, Sharath; Venkatesh, V.; Shinde, Digambar B.; Kumari, Sushma; Halder, Arjun; Verma, Sandeep; Banerjee, Rahul

    2015-04-01

    Covalent organic frameworks are a family of crystalline porous materials with promising applications. Although active research on the design and synthesis of covalent organic frameworks has been ongoing for almost a decade, the mechanisms of formation of covalent organic frameworks crystallites remain poorly understood. Here we report the synthesis of a hollow spherical covalent organic framework with mesoporous walls in a single-step template-free method. A detailed time-dependent study of hollow sphere formation reveals that an inside-out Ostwald ripening process is responsible for the hollow sphere formation. The synthesized covalent organic framework hollow spheres are highly porous (surface area ~1,500 m2 g-1), crystalline and chemically stable, due to the presence of strong intramolecular hydrogen bonding. These mesoporous hollow sphere covalent organic frameworks are used for a trypsin immobilization study, which shows an uptake of 15.5 μmol g-1 of trypsin.

  15. Instrumented module of the ATLAS tile calorimeter

    CERN Multimedia

    Laurent Guiraud

    1998-01-01

    The ATLAS tile calorimeter consists of steel absorber plates interspersed with plastic scintillator tiles. Interactions of high-energy hadrons in the plates transform the incident energy into a 'hadronic shower'. When shower particles traverse the scintillating tiles, the latter emit an amount of light proportional to the incident energy. This light is transmitted along readout fibres to a photomultiplier, where a detectable electrical signal is produced. These pictures show one of 64 modules or 'wedges' of the barrel part of the tile calorimeter, which are arranged to form a cylinder around the beam axis. The wedge has been instrumented with scintillators and readout fibres. Photos 03, 06: Checking the routing of the readout fibres into the girder that houses the photomultipliers. Photo 04: A view of the fibre bundles inside the girder.

  16. Design Methods for Fibre Reinforced Concrete

    DEFF Research Database (Denmark)

    Stang, Henrik

    1996-01-01

    The present paper describes the outline of a research project on Fibre Reinforced Concrete (FRC) currently being carried out in Denmark under the supervision of Danish Council of Technology, Danish Technical Research Council and Danish Natural Science Research Counsil.......The present paper describes the outline of a research project on Fibre Reinforced Concrete (FRC) currently being carried out in Denmark under the supervision of Danish Council of Technology, Danish Technical Research Council and Danish Natural Science Research Counsil....

  17. Optical fibre Fizeau-based OCT

    OpenAIRE

    Casaubieilh, P.; Ford, Helen D.; Ralph P. Tatam

    2004-01-01

    An optical fibre, Fizeau configuration Optical Coherence Tomography (OCT) system is presented in this paper. The interferometer is formed between the distal end of the sample-arm fibre and the sample itself. This ensures 'downlead insensitivity' ; polarisation variation is not a problem, as it is in the standard Michelson configuration. Path-length matching is performed by a secondary, bulk-optic scanning Mach-Zehnder interferometer. In this paper, we demonstrate the use of an opt...

  18. Polarisation control of DFB fibre lasers

    DEFF Research Database (Denmark)

    Varming, Poul; Philipsen, Jacob Lundgreen; Berendt, Martin Ole

    1998-01-01

    The polarisation properties of a distributed feedback (DFB) fibre laser are investigated. It is shown experimentally that the birefringence of the UV induced phase-shift is the dominating effect controlling the polarisation properties of the laser......The polarisation properties of a distributed feedback (DFB) fibre laser are investigated. It is shown experimentally that the birefringence of the UV induced phase-shift is the dominating effect controlling the polarisation properties of the laser...

  19. Design of distributed feedback fibre lasers

    DEFF Research Database (Denmark)

    Lauridsen, Vibeke Claudia; Søndergaard, Thomas; Varming, Poul

    1997-01-01

    A numerical model for erbium fibre lasers with Bragg gratings is presented. The model is used to optimize the location of a discrete phase-shift and the phase-shift magnitude for a distributed phase-shift.......A numerical model for erbium fibre lasers with Bragg gratings is presented. The model is used to optimize the location of a discrete phase-shift and the phase-shift magnitude for a distributed phase-shift....

  20. SILK FIBRE DEGRADATION AND ANALYSIS BY PROTEOMICS

    OpenAIRE

    YUKSELOGLU S.Muge; CANOGLU Suat

    2016-01-01

    Silk is one of the promising natural fibres and has a long established history in textile production throughout the centuries. Silk is produced by cultured silk worms, spiders, scorpions, mites and flies. It is extracellular proteinaceous fibres which consist of highly crystalline and insoluble proteins, the fibroins glued with sericin and an amourphous protein. On the other hand, understanding and controlling the degradation of protein materials are important for determining quality and the...

  1. Energy transfer during the hydroentanglement of fibres

    CSIR Research Space (South Africa)

    Moyo, D

    2012-10-01

    Full Text Available , and the resultant degree of fibre entanglement, determines the tensile strength of the nonwoven fabric as a consequence of the inter-fibre friction. Here, the relationship between hydroentangling energy from the waterjets and the changes it brings about... in the nonwoven fabric strength were studied. In the study, the energies of the waterjets transferred to every fabric sample as a function of the waterjet pressure, machine speed, machine efficiency and the web area weight were quantified, and the resultant...

  2. Fibred knots and twisted Alexander invariants

    OpenAIRE

    Cha, Jae Choon

    2001-01-01

    We introduce a new algebraic topological technique to detect non-fibred knots in the three sphere using the twisted Alexander invariants. As an application, we show that for any Seifert matrix of a knot with a nontrivial Alexander polynomial, there exist infinitely many non-fibered knots with the given Seifert matrix. We illustrate examples of knots that have trivial Alexander polynomials but do not have twisted Alexander invariants of fibred knots.

  3. Dietary fibre metabolism and colon function

    OpenAIRE

    Tadesse, Kebede

    1980-01-01

    Dietary fibre is a complex material made up of plant cell polymers which are not digested by gastrointestinal enzymes of man but partially fermented by the commensal bacteria in the colon. Since in man most of the colon is not readily accessible, indirect methods must be sought to study dietary fibre metabolism and its effects on colon function. In this project gas chromatographic measurements of two of the end products of fermentation, H2 and CH^, which are expired in the b...

  4. Photonic crystal fibres in the market

    DEFF Research Database (Denmark)

    Broeng, Jes; Laurila, Marko; Noordegraaf, Danny

    2011-01-01

    Photonic crystal fibres (PCFs) emerged as a research topic in the mid 1990'ies [1]. Today, 15 years later, these fibres are increasing deployed in various commercial markets. Here, we will address three of these markets; medical imaging, materials processing and sensors. We will describe how...... the PCFs provide radical improvements and illustrate the strong diversity in the evolution of PCFs to serve these different markets....

  5. Dynamic response analysis of DFB fibre lasers

    DEFF Research Database (Denmark)

    Yujun, Qian; Varming, Poul; Povlsen, Jørn Hedegaard

    1998-01-01

    We present a model for relative intensity noise (RIN) in DFB fibre lasers which predicts measured characteristics accurately. Calculation results implies that the RIN decreases rapidly with stronger Bragg grating and higher pump power. We propose here a simplified model based on three spatially...... independent rate equations to describe the dynamic response of erbium doped DFB fibre lasers on pump power fluctuations, using coupled-mode theory to calculate the steady-state hole-burning of the erbium ion inversion...

  6. Fibre positioning algorithms for the WEAVE spectrograph

    Science.gov (United States)

    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.

  7. Dietary fibre in infancy and childhood.

    Science.gov (United States)

    Edwards, C A; Parrett, A M

    2003-02-01

    There is very little evidence for the effects of dietary fibre in young children and current dietary guidelines are based on assumptions and data extrapolated from studies in adults. The first years of life may be critical for the establishment of a healthy colonic microflora, as well as good eating habits. The lack of clear and well-founded guidelines for the intake of dietary fibre in childhood may hinder both factors. The fears that a high-fibre diet in children definition of dietary fibre include oligosaccharides, which may act as prebiotics. There are potential health benefits of including oligosaccharides in the diets of infants and children, but more research is needed to consider the long-term effects. The immature intestine of the infant may also result in a greater amount of starch entering the colon during weaning, and this starch would now be considered dietary fibre under the new definitions. Much new research is needed to allow adequate recommendations for the intake of dietary fibre in childhood based on data collected in appropriate age-groups.

  8. Mode conversion in magneto photonic crystal fibre

    Energy Technology Data Exchange (ETDEWEB)

    Otmani, Hamza, E-mail: otmanih@yahoo.fr [Laboratoire Micro-systèmes et Instrumentation (LMI), Université de Constantine 1, Constantine (Algeria); Bouchemat, Mohamed [Laboratoire Micro-systèmes et Instrumentation (LMI), Université de Constantine 1, Constantine (Algeria); Hocini, Abdesselam [Laboratoire Micro-systèmes et Instrumentation (LMI), Université de Constantine 1, Constantine (Algeria); Département d' Electronique, Faculté de Technologie, Université de M’sila, BP 166, Route Ichebilia, M’sila 28000 (Algeria); Boumaza, Touraya; Benmerkhi, Ahlem [Laboratoire Micro-systèmes et Instrumentation (LMI), Université de Constantine 1, Constantine (Algeria)

    2017-01-01

    The first concept of an integrated isolator was based on nonreciprocal TE–TM mode conversion, the nonreciprocal coupling between these modes is caused by the Faraday rotation if the magnetization is aligned along the z–axis, parallel to mode propagation. We propose to study this magneto-optical phenomenon, by the simulation of magneto photonic crystal fibre (MPCF), it consists of a periodic triangular lattice of air-holes filled with magnetic fluid which consists of magnetic nanoparticles into a BIG (Bismuth Iron Garnet) fibre. We simulated the influence of gyrotropy and the wavelength, and calculated Faraday rotation and modal birefringence. In this fibre the light is guided by internal total reflection, like classical fibres. However it was shown that they could function on a mode conversion much stronger than conventional fibres. - Highlights: • We propose to study mode conversion TE–TM, by the simulation of magneto photonic crystal fibre (MPCF). • We simulated the influence of gyrotropy. • We simulated the wavelength. • We calculated Faraday rotation. • We calculated modal birefringence.

  9. Long-term evaluation of hollow screw and hollow cylinder dental implants : Clinical and radiographic results after 10 years

    NARCIS (Netherlands)

    Telleman, Gerdien; Meijer, Henny J. A.; Raghoebar, Gerry M.

    Background: In 1988, an implant manufacturer offered a new dental implant system, with a wide choice of hollow cylinder (HC) and hollow screw (HS) implants. The purpose of this retrospective study of HS and HC implants was to evaluate clinical and radiographic parameters of peri-implant tissue and

  10. Metal-Matrix/Hollow-Ceramic-Sphere Composites

    Science.gov (United States)

    Baker, Dean M.

    2011-01-01

    A family of metal/ceramic composite materials has been developed that are relatively inexpensive, lightweight alternatives to structural materials that are typified by beryllium, aluminum, and graphite/epoxy composites. These metal/ceramic composites were originally intended to replace beryllium (which is toxic and expensive) as a structural material for lightweight mirrors for aerospace applications. These materials also have potential utility in automotive and many other terrestrial applications in which there are requirements for lightweight materials that have high strengths and other tailorable properties as described below. The ceramic component of a material in this family consists of hollow ceramic spheres that have been formulated to be lightweight (0.5 g/cm3) and have high crush strength [40.80 ksi (.276.552 MPa)]. The hollow spheres are coated with a metal to enhance a specific performance . such as shielding against radiation (cosmic rays or x rays) or against electromagnetic interference at radio and lower frequencies, or a material to reduce the coefficient of thermal expansion (CTE) of the final composite material, and/or materials to mitigate any mismatch between the spheres and the matrix metal. Because of the high crush strength of the spheres, the initial composite workpiece can be forged or extruded into a high-strength part. The total time taken in processing from the raw ingredients to a finished part is typically 10 to 14 days depending on machining required.

  11. Hollow Pollen Shells to Enhance Drug Delivery

    Science.gov (United States)

    Diego-Taboada, Alberto; Beckett, Stephen T.; Atkin, Stephen L.; Mackenzie, Grahame

    2014-01-01

    Pollen grain and spore shells are natural microcapsules designed to protect the genetic material of the plant from external damage. The shell is made up of two layers, the inner layer (intine), made largely of cellulose, and the outer layer (exine), composed mainly of sporopollenin. The relative proportion of each varies according to the plant species. The structure of sporopollenin has not been fully characterised but different studies suggest the presence of conjugated phenols, which provide antioxidant properties to the microcapsule and UV (ultraviolet) protection to the material inside it. These microcapsule shells have many advantageous properties, such as homogeneity in size, resilience to both alkalis and acids, and the ability to withstand temperatures up to 250 °C. These hollow microcapsules have the ability to encapsulate and release actives in a controlled manner. Their mucoadhesion to intestinal tissues may contribute to the extended contact of the sporopollenin with the intestinal mucosa leading to an increased efficiency of delivery of nutraceuticals and drugs. The hollow microcapsules can be filled with a solution of the active or active in a liquid form by simply mixing both together, and in some cases operating a vacuum. The active payload can be released in the human body depending on pressure on the microcapsule, solubility and/or pH factors. Active release can be controlled by adding a coating on the shell, or co-encapsulation with the active inside the shell. PMID:24638098

  12. High power laser source for atom cooling based on reliable telecoms technology with all fibre frequency stabilisation

    Science.gov (United States)

    Legg, Thomas; Farries, Mark

    2017-02-01

    Cold atom interferometers are emerging as important tools for metrology. Designed into gravimeters they can measure extremely small changes in the local gravitational field strength and be used for underground surveying to detect buried utilities, mineshafts and sinkholes prior to civil works. To create a cold atom interferometer narrow linewidth, frequency stabilised lasers are required to cool the atoms and to setup and measure the atom interferometer. These lasers are commonly either GaAs diodes, Ti Sapphire lasers or frequency doubled InGaAsP diodes and fibre lasers. The InGaAsP DFB lasers are attractive because they are very reliable, mass-produced, frequency controlled by injection current and simply amplified to high powers with fibre amplifiers. In this paper a laser system suitable for Rb atom cooling, based on a 1560nm DFB laser and erbium doped fibre amplifier, is described. The laser output is frequency doubled with fibre coupled periodically poled LiNbO3 to a wavelength of 780nm. The output power exceeds 1 W at 780nm. The laser is stabilised at 1560nm against a fibre Bragg resonator that is passively temperature compensated. Frequency tuning over a range of 1 GHz is achieved by locking the laser to sidebands of the resonator that are generated by a phase modulator. This laser design is attractive for field deployable rugged systems because it uses all fibre coupled components with long term proven reliability.

  13. Immunomodulatory effect of fibres, probiotics and synbiotics in different life-stages Efecto inmunomodulador de la fibra, probióticos y simbióticos en las diferentes etapas de la vida

    OpenAIRE

    J. Romeo; E. De Nova; J. Wärnberg; S. Gómez-Martínez; L. E. Díaz Ligia; Marcos, A.

    2010-01-01

    Chronic diseases associated to modern lifestyle habits are usually related to immune system malfunction. In this context, since diet is very well-known to modulate host resistance to infectious and inflammatory processes, the consumption of fibre and probiotics seems to be a promising nutritional tool for immune system modulation in different populations. Health effects of dietary fibres and probiotics have been extensively documented in numerous epidemiological and intervention studies, espe...

  14. Fibre-matrix interface properties in a wood fibre reinforced cement matrix

    NARCIS (Netherlands)

    Sierra Beltran, M.G.; Schlangen, H.E.J.G.

    2010-01-01

    Wood fibres can be a low cost reinforcement for cementitious materials for structural applications. In order to design a ductile cementitious material reinforced with softwood fibres the fibrematrix interface properties are studied. Pullout tests have been carried out to determine the bond strength

  15. Vibrated and self-compacting fibre reinforced concrete: experimental investigation on the fibre orientation

    Science.gov (United States)

    Conforti, A.; Plizzari, G. A.; Zerbino, R.

    2017-09-01

    In addition to the fibre type and content, the residual properties of fibre reinforced concrete are influenced by fibre orientation. Consequently, the performance fibre reinforced concrete can be affected by its fresh properties (workability, flowing capacity) and by casting and compaction processes adopted. This paper focuses on the study of the orientation of steel or macro-synthetic fibres in two materials characterized by very different fresh properties: vibrated and self-compacting concrete. Four rectangular slabs 1800 mm long, 925 mm wide and 100 mm high were produced changing concrete and fibre type. From each slab, eighteen small prisms (550 mm long) were firstly cut either orthogonal or parallel to casting direction and, secondly, notched and tested in bending according to EN 14651. Experimental results showed that the toughness properties of a thin slab significantly varies both in vibrated and self-compacting concrete, even if in case of self-compacting concrete this variation resulted higher. Steel fibres led to greater variability of results compared to polymer one, underlining a different fibre orientation. A discussion on the relative residual capacity measured on the prisms sawn from the slabs and the parameters obtained from standard specimens is performed.

  16. EVALUATION OF FIBRE LENGTH DISTRIBUTION IN A SHORT GLASS FIBRE REINFORCED PA-6

    Directory of Open Access Journals (Sweden)

    Camilla Ravalico

    2015-09-01

    Full Text Available The aim of this work is to evaluate the fibre length distribution in a polyamide reinforced by short glass fibre. The fibre length and the fibre orientation distributions strongly influence the mechanical properties of short fibre reinforced composites. The sample investigated is a 30GFPA6 (polyamide-6 reinforced by 30 % by weight glass fibre, extracted from an injection-moulded plate. The digital reconstruction of the three-dimensional structure of the sample was obtained by synchrotron radiation micro-computed tomography (micro-CT, a high spatial resolution non-destructive technique. One global and one local method have been tested for the automatic evaluation of the fibre length distribution in our sample. The global method is based on the mean fibre length distribution computed from the Star Length Distribution (SLD, a morphological parameter. The local method is based on a 3D skeletonize function. The results are discussed in the light of the experimental data available in literature.

  17. Hybrid RSOA and fibre raman amplified long reach feeder link for WiMAX-on-fibre

    DEFF Research Database (Denmark)

    Amaya Fernández, Ferney Orlando; Martinez, Javier; Yu, Xianbin

    2009-01-01

    A distributed fibre Raman amplified long reach optical access feeder link using a reflective semiconductor optical amplifier in the remote base station is experimentally demonstrated for supporting WiMAXover- fibre transmission. The measured values for the error vector magnitude for quadrature ph...

  18. Crack Growth Monitoring by Embedded Optical Fibre Bragg Grating Sensors: Fibre Reinforced Plastic Crack Growing Detection

    DEFF Research Database (Denmark)

    Pereira, Gilmar Ferreira; Mikkelsen, Lars Pilgaard; McGugan, Malcolm

    2015-01-01

    This article presents a novel method to asses a crack growing/damage event in fibre reinforced plastic, or adhesive using Fibre Bragg Grating (FBG) sensors embedded in a host material. Different features of the crack mechanism that induce a change in the FBG response were identified. Double...

  19. The coupling performance of photonic crystal fibres in fibre stellar interferometry

    DEFF Research Database (Denmark)

    Corbett, J.; Dabirian, A.; Butterley, T.

    2006-01-01

    the theoretical performance of coupling the telescope point spread function directly into LMA PCFs. We find that a single LMA fibre can replace as many as three step-index fibres for atmospheric seeing characterized by D-T/r(o) >= 2 with approximately the same coupling performance and a slower feed from...

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

    Directory of Open Access Journals (Sweden)

    Xiaoling Liu

    2013-01-01

    Full Text Available 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.

  1. Cognitive digital receiver for burst mode phase modulated radio over fiber links

    DEFF Research Database (Denmark)

    Guerrero Gonzalez, Neil; Zibar, Darko; Tafur Monroy, Idelfonso

    2010-01-01

    A novel cognitive receiver for modulation format recognition with reconfigurable carrier recovery scheme is proposed and experimentally demonstrated for phase modulated radio-over-fibre links. Demodulation of burst-mode mixed modulation formats (PSK and QAM) is demonstrated after 40km of transmis......A novel cognitive receiver for modulation format recognition with reconfigurable carrier recovery scheme is proposed and experimentally demonstrated for phase modulated radio-over-fibre links. Demodulation of burst-mode mixed modulation formats (PSK and QAM) is demonstrated after 40km...

  2. LHCb : A Scintillating Fibre Trackind Detector for the LHCb Upgrade

    CERN Multimedia

    Lindner, Rolf

    2014-01-01

    LHCb is preparing the upgrade which is scheduled to be installed in 2018/19. The Scintillating Fibre (SciFi) Tracker will be designed to replace the current tracking system downstream of the magnet, required to run at an increased luminosity of 1 - 2 10$^{33}$ cm$^{-2}$s$^{-1}$ and to collect a total of 50fb$^{-1}$ of data. The readout of the detector will be at 40MHz, applying a full software based trigger for every single bunch crossing. The SciFi Tracker consists of 12 planes covering a total surface of 350 m2. Modules are based on 2.5 m long multilayer ribbons made of 250 um diameter scintillating fibres as the active medium and signal transport. Silicon photomultiplier (SiPM) arrays with 128 channels at a width of 250 um are used for the readout. The signals from the SiPMS are digitized on an ASIC chip before reconstructing the track hit position within an FPGA on the front-end board. Several challenges facing this detector and the significant progress over the last year will be presented regarding the p...

  3. The selection of small forest hollows for pollen analysis in boreal and temperate forest regions

    DEFF Research Database (Denmark)

    Overballe-Petersen, Mette V; Bradshaw, Richard H.W.

    2011-01-01

    Small forest hollows represent a specialised site type for pollen analysis, since they mainly record the vegetation within an approximate radius of 20-100 m from the hollow. We discuss how to choose the most appropriate small forest hollow for pollen analysis. Hollow size, site topography, location...

  4. Hemp fibres: Enzymatic effect of microbial processing on fibre bundle structure

    DEFF Research Database (Denmark)

    Thygesen, Anders; Liu, Ming; Meyer, Anne S.

    2013-01-01

    The effects of microbial pretreatment on hemp fibres were evaluated after microbial retting using the white rot fungi Ceriporiopsis subvermispora and Phlebia radiata Cel 26 and water retting. Based on chemical composition, P. radiata Cel 26 showed the highest selectivity for pectin and lignin...... degradation and lowest cellulose loss (14%) resulting in the highest cellulose content (78.4%) for the treated hemp fibres. The pectin and lignin removal after treatment with P. radiata Cel 26 were of the order 82% and 50%, respectively. Aligned epoxy-matrix composites were made from hemp fibres defibrated...... hemp fibres were badly impregnated due to porosity caused by surface impurities such as epidermis and other pectin rich plant cells. The pectin and lignin mainly located in the outer part of the fibres were assumed to be extracted and degraded by pectinase and peroxidase enzymes produced by the fungi....

  5. Formation map of air-liquid hollow profile under microgravity

    Energy Technology Data Exchange (ETDEWEB)

    Ohira, Y.; Kuga, Y.; Ando, K. [Muroran Institute of Technology, Hokkaido (Japan). Dept. of Applied Chemistry; Idogawa, K.; Fukuda, T. [Hokkaido National Industrial Research Institute, Hokkaido (Japan)

    2000-04-01

    From the viewpoint of oxygen recovery and supply in a space station, the formation of an air-liquid hollow profile which has a suitable interface shape to cultivate microalgae under microgravity conditions is experimentally investigated. The air-liquid interface profiles in a rotating vessel were observed and recorded. The effects of the modified Weber number and modified Reynolds number on formation of the air-liquid hollow profile were experimentally investigated. We developed a basis for judging conditions forming the air-liquid hollow profile from the video images. When the volume ratio of the liquid/vessel is 0.60 and the modified Weber number is greater than 2.2, it is found that the air-liquid hollow profile forms and is independent of the modified Reynolds number. From the experimental results using liquids with different surface tension, the validity of using the modified Weber number is confirmed as a dimensionless number for judging the formation of the air-liquid hollow profile. It is experimentally found that the formation conditions for the air-liquid hollow profile under microgravity can be determined by the modified Weber number and the volume ratio of the liquid/vessel. In a map of the volume ratio of the liquid/vessel vs. the modified Weber number, the discrimination of the formation of the air-liquid hollow profile is performed by a line experimentally obtained in this study. (author)

  6. Experimental and numerical study on refractive index sensors based on fibre Bragg gratings inscribed in multimode fibre

    Science.gov (United States)

    Filipe Kuhne, Jean; Rocha, Ana Maria; de Oliveira, Valmir; José Kalinowski, Hypolito; Canute Kamikawachi, Ricardo

    2018-02-01

    In this work is reported the experimental and numerical results of the refractive index response of etched fibre Bragg gratings written in a graded index multimode fibre. The responses of the modes coupled by the grating inscribed in a multimode fibre are compared with the mode coupled by a grating inscribed in single mode fibre. The results of this study show that the refractive index sensitivity and the dynamical range of etched fibre Bragg gratings written in multimode fibres are higher than the ones verified in single-mode fibres. The determination of oil-biodiesel blend concentrations are also compared as an example of practical applications. It is shown that a greater core diameter of the multimode fibre enables the Bragg gratings to exhibit enhanced sensitivity without requiring further fibre diameter reduction.

  7. Latest developments in silica fibre luminescence dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, D. A.; Abdul S, S. F.; Jafari, S. M.; Alanazi, A. [University of Surrey, Department of Physics, GU2 7XH Guildford, Surrey (United Kingdom); Amouzad M, G. [University of Malaya, Faculty of Engineering, Department of Electrical Engineering, Integrated Lightwave Research Group, 50603 Kuala Lumpur (Malaysia); Addul R, H. A.; Mizanur R, A. K. M.; Zubair, H. T.; Begum, M.; Yusoff, Z.; Omar, N. Y. M. [Multimedia University, Faculty of Engineering, 2010 Cyberjaya, Selangor (Malaysia); Maah, M. J. [University of Malaya, Department of Chemistry, 50603 Kuala Lumpur (Malaysia); Collin, S. [National Physical Laboratory, Hampton Road, Teddington, TW11 OLW Middlesex (United Kingdom); Mat-Sharif, K. A.; Muhd-Yassin, S. Z.; Zulkifli, M. I., E-mail: d.a.bradley@surrey.ac.uk [Telekom Malaysia Research and Development Sdn Bhd., 63000 Cyberjaya, Selangor (Malaysia)

    2015-10-15

    Full text: Using tailor made sub-mm diameter doped-silica fibres, we are carrying out luminescence dosimetry studies for a range of situations, including thermoluminescence (Tl)investigations on a liquid alpha source formed of {sup 223}RaCl (the basis of the Bayer Health care product Xofigo), the Tl response to a 62 MeV proton source and Tl response to irradiation from an {sup 241}Am-Be neutron source. In regard to the former, in accord with the intrinsic high linear energy transfer (Let) and short path length (<100 um) of the α-particles in calcified tissue, the product is in part intended as a bone-seeking radionuclide for treatment of metastatic cancer, offering high specificity and efficacy. The Tl yield of Ge-doped SiO{sub 2} fibres has been investigated including for photonic crystal fibre un collapsed, flat fibres and single mode fibres, these systems offering many advantages over conventional passive dosimetry types. In particular, one can mention comparable and even superior sensitivity, an effective atomic number Z{sub eff} of the silica dosimetric material close to that of bone, and the glassy nature of the fibres offering the additional advantage of being able to place such dosimeters directly into liquid environments. Finally we review the use of our tailor made fibres for on-line radioluminescence measurements of radiotherapy beams. The outcome from these various lines of research is expected to inform development of doped fiber radiation dosimeters of versatile utility, ranging from clinical applications through to industrial studies and environmental evaluations. (Author)

  8. A prototype scintillating-fibre tracker for the cosmic-ray muon tomography of legacy nuclear waste containers

    Energy Technology Data Exchange (ETDEWEB)

    Al Jebali, Ramsey; Mahon, David; Clarkson, Anthony; Ireland, Dave G; Kaiser, Ralf [University of Glasgow, Kelvin Building, University Avenue, Glasgow, G12 8QQ, Scotland, (United Kingdom); Mountford, David; Ryan, Matt; Shearer, Craig; Yang, Guangliang [National Nuclear Laboratory, Central Laboratory, Sellafield, Seascale, Cumbria, CA20 1PG, England, (United Kingdom)

    2015-07-01

    A prototype scintillating-fibre detector system has been developed at the University of Glasgow in collaboration with the UK National Nuclear Laboratory (NNL) for the nondestructive assay of UK legacy nuclear waste containers. This system consists of two tracking modules above, and two below, the container under interrogation. Each module consists of two orthogonal planes of 2 mm-pitch fibres yielding one space point. Per plane, 128 fibres are read out by a single Hamamatsu H8500 64-channel MAPMT with two fibres multiplexed onto each pixel. A dedicated mapping scheme has been developed to avoid space point ambiguities and retain the high spatial resolution provided by the fibres. The configuration allows the reconstruction of the incoming and scattered muon trajectories, thus enabling the container content, with respect to atomic number Z, to be determined. Results are shown from experimental data collected for high-Z objects within an air matrix and, for the first time, within a shielded, concrete-filled container. These reconstructed images show clear discrimination between the low, medium and high-Z materials present, with dimensions and positions determined with sub-centimetre precision. (authors)

  9. Improved Rare-Earth Emitter Hollow Cathode

    Science.gov (United States)

    Goebel, Dan M.

    2011-01-01

    An improvement has been made to the design of the hollow cathode geometry that was created for the rare-earth electron emitter described in Compact Rare Earth Emitter Hollow Cathode (NPO-44923), NASA Tech Briefs, Vol. 34, No. 3 (March 2010), p. 52. The original interior assembly was made entirely of graphite in order to be compatible with the LaB6 material, which cannot be touched by metals during operation due to boron diffusion causing embrittlement issues in high-temperature refractory materials. Also, the graphite tube was difficult to machine and was subject to vibration-induced fracturing. This innovation replaces the graphite tube with one made out of refractory metal that is relatively easy to manufacture. The cathode support tube is made of molybdenum or molybdenum-rhenium. This material is easily gun-bored to near the tolerances required, and finish machined with steps at each end that capture the orifice plate and the mounting flange. This provides the manufacturability and robustness needed for flight applications, and eliminates the need for expensive e-beam welding used in prior cathodes. The LaB6 insert is protected from direct contact with the refractory metal tube by thin, graphite sleeves in a cup-arrangement around the ends of the insert. The sleeves, insert, and orifice plate are held in place by a ceramic spacer and tungsten spring inserted inside the tube. To heat the cathode, an insulating tube is slipped around the refractory metal hollow tube, which can be made of high-temperature materials like boron nitride or aluminum nitride. A screw-shaped slot, or series of slots, is machined in the outside of the ceramic tube to constrain a refractory metal wire wound inside the slot that is used as the heater. The screw slot can hold a single heater wire that is then connected to the front of the cathode tube by tack-welding to complete the electrical circuit, or it can be a double slot that takes a bifilar wound heater with both leads coming out

  10. Influence of the Testing Gage Length on the Strength, Young's Modulus and Weibull Modulus of Carbon Fibres and Glass Fibres

    Directory of Open Access Journals (Sweden)

    Luiz Claudio Pardini

    2002-10-01

    Full Text Available Carbon fibres and glass fibres are reinforcements for advanced composites and the fiber strength is the most influential factor on the strength of the composites. They are essentially brittle and fail with very little reduction in cross section. Composites made with these fibres are characterized by a high strength/density ratio and their properties are intrisically related to their microstructure, i.e., amount and orientation of the fibres, surface treatment, among other factors. Processing parameters have an important role in the fibre mechanical behaviour (strength and modulus. Cracks, voids and impurities in the case of glass fibres and fibrillar misalignments in the case of carbon fibres are created during processing. Such inhomogeneities give rise to an appreciable scatter in properties. The most used statistical tool that deals with this characteristic variability in properties is the Weibull distribution. The present work investigates the influence of the testing gage length on the strength, Young's modulus and Weibull modulus of carbon fibres and glass fibres. The Young's modulus is calculated by two methods: (i ASTM D 3379M, and (ii interaction between testing equipment/specimen The first method resulted in a Young modulus of 183 GPa for carbon fibre, and 76 GPa for glass fibre. The second method gave a Young modulus of 250 GPa for carbon fibre and 50 GPa for glass fibre. These differences revelead differences on how the interaction specimen/testing machine can interfere in the Young modulus calculations. Weibull modulus can be a tool to evaluate the fibre's homogeneity in terms of properties and it is a good quality control parameter during processing. In the range of specimen gage length tested the Weibull modulus for carbon fibre is ~ 3.30 and for glass fibres is ~ 5.65, which indicates that for the batch of fibres tested, the glass fibre is more uniform in properties.

  11. Bench Scale Thin Film Composite Hollow Fiber Membranes for Post-Combustion Carbon Dioxide Capture

    Energy Technology Data Exchange (ETDEWEB)

    Glaser, Paul [General Electric Global Research, Niskayuna, NY (United States); Bhandari, Dhaval [General Electric Global Research, Niskayuna, NY (United States); Narang, Kristi [General Electric Global Research, Niskayuna, NY (United States); McCloskey, Pat [General Electric Global Research, Niskayuna, NY (United States); Singh, Surinder [General Electric Global Research, Niskayuna, NY (United States); Ananthasayanam, Balajee [General Electric Global Research, Niskayuna, NY (United States); Howson, Paul [General Electric Global Research, Niskayuna, NY (United States); Lee, Julia [General Electric Global Research, Niskayuna, NY (United States); Wroczynski, Ron [General Electric Global Research, Niskayuna, NY (United States); Stewart, Frederick [Idaho National Lab. (INL), Idaho Falls, ID (United States); Orme, Christopher [Idaho National Lab. (INL), Idaho Falls, ID (United States); Klaehn, John [Idaho National Lab. (INL), Idaho Falls, ID (United States); McNally, Joshua [Idaho National Lab. (INL), Idaho Falls, ID (United States); Rownaghi, Ali [Georgia Inst. of Technology, Atlanta, GA (United States); Lu, Liu [Georgia Inst. of Technology, Atlanta, GA (United States); Koros, William [Georgia Inst. of Technology, Atlanta, GA (United States); Goizueta, Roberto [Georgia Inst. of Technology, Atlanta, GA (United States); Sethi, Vijay [Western Research Inst., Laramie, WY (United States)

    2015-04-01

    GE Global Research, Idaho National Laboratory (INL), Georgia Institute of Technology (Georgia Tech), and Western Research Institute (WRI) proposed to develop high performance thin film polymer composite hollow fiber membranes and advanced processes for economical post-combustion carbon dioxide (CO2) capture from pulverized coal flue gas at temperatures typical of existing flue gas cleanup processes. The project sought to develop and then optimize new gas separations membrane systems at the bench scale, including tuning the properties of a novel polyphosphazene polymer in a coating solution and fabricating highly engineered porous hollow fiber supports. The project also sought to define the processes needed to coat the fiber support to manufacture composite hollow fiber membranes with high performance, ultra-thin separation layers. Physical, chemical, and mechanical stability of the materials (individual and composite) towards coal flue gas components was considered via exposure and performance tests. Preliminary design, technoeconomic, and economic feasibility analyses were conducted to evaluate the overall performance and impact of the process on the cost of electricity (COE) for a coal-fired plant including capture technologies. At the onset of the project, Membranes based on coupling a novel selective material polyphosphazene with an engineered hollow fiber support was found to have the potential to capture greater than 90% of the CO2 in flue gas with less than 35% increase in COE, which would achieve the DOE-targeted performance criteria. While lab-scale results for the polyphosphazene materials were very promising, and the material was incorporated into hollow-fiber modules, difficulties were encountered relating to the performance of these membrane systems over time. Performance, as measured by both flux of and selectivity for CO2 over other flue gas constituents was found to deteriorate over time, suggesting a system that was

  12. EFFECTS OF PRESSURE AND TEMPERATURE ON ULTRAFILTRATION HOLLOW FIBER MEMBRANE IN MOBILE WATER TREATMENT SYSTEM

    Directory of Open Access Journals (Sweden)

    ROSDIANAH RAMLI

    2016-07-01

    Full Text Available In Sabah, Malaysia, there are still high probability of limited clean water access in rural area and disaster site. Few villages had been affected in Pitas due to improper road access, thus building a water treatment plant there might not be feasible. Recently, Kundasang area had been affected by earthquake that caused water disruption to its people due to the damage in the underground pipes and water tanks. It has been known that membrane technology brought ease in making mobile water treatment system that can be transported to rural or disaster area. In this study, hollow fiber membrane used in a mobile water treatment system due to compact and ease setup. Hollow fiber membrane was fabricated into small module at 15 and 30 fibers to suit the mobile water treatment system for potable water production of at least 80 L/day per operation. The effects of transmembrane pressure (TMP and feed water temperature were investigated. It was found that permeate flux increases by more than 96% for both 15 and 30 fiber bundles with increasing pressure in the range of 0.25 to 3.0 bar but dropped when the pressure reached maximum. Lower temperature of 17 to 18˚C increase the water viscosity by 15% from normal temperature of water at 24˚C, making the permeate flux decreases. The fabricated modules effectively removed 96% turbidity of the surface water sample tested.

  13. Axisymmetric Vibration of Piezo-Lemv Composite Hollow Multilayer Cylinder

    Directory of Open Access Journals (Sweden)

    E. S. Nehru

    2012-01-01

    Full Text Available Axisymmetric vibration of an infinite piezolaminated multilayer hollow cylinder made of piezoelectric layers of 6 mm class and an isotropic LEMV (Linear Elastic Materials with Voids layers is studied. The frequency equations are obtained for the traction free outer surface with continuity conditions at the interfaces. Numerical results are carried out for the inner, middle, and outer hollow piezoelectric layers bonded by LEMV (It is hypothetical material layers and the dispersion curves are compared with that of a similar 3-layer model and of 3 and 5 layer models with inner, middle, and outer hollow piezoelectric layers bonded by CFRP (Carbon fiber reinforced plastics.

  14. Hollow fiber membranes and methods for forming same

    Science.gov (United States)

    Bhandari, Dhaval Ajit; McCloskey, Patrick Joseph; Howson, Paul Edward; Narang, Kristi Jean; Koros, William

    2016-03-22

    The invention provides improved hollow fiber membranes having at least two layers, and methods for forming the same. The methods include co-extruding a first composition, a second composition, and a third composition to form a dual layer hollow fiber membrane. The first composition includes a glassy polymer; the second composition includes a polysiloxane; and the third composition includes a bore fluid. The dual layer hollow fiber membranes include a first layer and a second layer, the first layer being a porous layer which includes the glassy polymer of the first composition, and the second layer being a polysiloxane layer which includes the polysiloxane of the second composition.

  15. Development of hollow electron beams for proton and ion collimation

    CERN Document Server

    Stancari, G.; Kuznetsov, G.; Shiltsev, V.; Still, D.A.; Valishev, A.; Vorobiev, L.G.; Assmann, R.; Kabantsev, A.

    2010-01-01

    Magnetically confined hollow electron beams for controlled halo removal in high-energy colliders such as the Tevatron or the LHC may extend traditional collimation systems beyond the intensity limits imposed by tolerable material damage. They may also improve collimation performance by suppressing loss spikes due to beam jitter and by increasing capture efficiency. A hollow electron gun was designed and built. Its performance and stability were measured at the Fermilab test stand. The gun will be installed in one of the existing Tevatron electron lenses for preliminary tests of the hollow-beam collimator concept, addressing critical issues such as alignment and instabilities of the overlapping proton and electron beams

  16. Development of hollow electron beams for proton and ion collimation

    CERN Document Server

    Stancari, G; Kuznetsov, G; Shiltsev, V; Still, D A; Valishev, A; Vorobiev, L G; Assmann, R; Kabantsev, A

    2012-01-01

    Magnetically confined hollow electron beams for controlled halo removal in high-energy colliders such as the Tevatron or the LHC may extend traditional collimation systems beyond the intensity limits imposed by tolerable material damage. They may also improve collimation performance by suppressing loss spikes due to beam jitter and by increasing capture efficiency. A hollow electron gun was designed and built. Its performance and stability were measured at the Fermilab test stand. The gun will be installed in one of the existing Tevatron electron lenses for preliminary tests of the hollow-beam collimator concept, addressing critical issues such as alignment and instabilities of the overlapping proton and electron beams.

  17. Permeability of Hollow Microspherical Membranes to Helium

    Science.gov (United States)

    Zinoviev, V. N.; Kazanin, I. V.; Pak, A. Yu.; Vereshchagin, A. S.; Lebiga, V. A.; Fomin, V. M.

    2016-01-01

    This work is devoted to the study of the sorption characteristics of various hollow microspherical membranes to reveal particles most suitable for application in the membrane-sorption technologies of helium extraction from a natural gas. The permeability of the investigated sorbents to helium and their impermeability to air and methane are shown experimentally. The sorption-desorption dependences of the studied sorbents have been obtained, from which the parameters of their specific permeability to helium are calculated. It has been established that the physicochemical modification of the original particles exerts a great influence on the coefficient of the permeability of a sorbent to helium. Specially treated cenospheres have displayed high efficiency as membranes for selective extraction of helium.

  18. Hollow-tip scanning photoelectron microscopy

    Science.gov (United States)

    Cherkun, A. P.; Mironov, B. N.; Aseyev, S. A.; Chekalin, S. V.

    2014-07-01

    A new type of microscopy based on scanning in vacuum by a beam of charged particles transmitted through a hollow probe has been implemented. This approach provides controllable motion of spatially localized ion, electron, molecular (atomic), and soft X-ray beams and investigation of the surface in the shear force mode. In the photoelectron mode, in which electrons are transmitted through a 2-μm quartz capillary, a surface profile of gadolinium irradiated by 400-nm femtosecond laser pulses has been visualized with a subwave spatial resolution. The new method of microscopy opens an opportunity of investigations in the field of nanometer local photodesorption of molecular ions (one of the last ideas of V.S. Letokhov).

  19. Hollow micro string based calorimeter device

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention relates to a micron-scale calorimeter and a calorimetry method utilizing the micron-scale calorimeter. In accordance with the invention, there is provided a micron-scale calorimeter comprising a micro-channel string, being restrained at at least two longitudinally distanced...... positions so as to form a free released double clamped string in-between said two longitudinally distanced positions said micro-channel string comprising a microfluidic channel having a closed cross section and extending in the longitudinal direction of the hollow string, acoustical means adapted...... to oscillate the string at different frequencies by emitting sound waves towards the string, optical means adapted to detect oscillating frequencies of the string, and controlling means controlling the strength and frequency of the sound wave emitted by the acoustical means and receiving a signal from...

  20. Two-piece hollow bulb obturator

    Directory of Open Access Journals (Sweden)

    Subramaniam Elangovan

    2011-01-01

    Full Text Available There are various types of obturator fabrication achievable by prosthodontist. Maxillectomy, which is a term used by head and neck surgeons and prosthodontists to describe the partial or total removal of the maxilla in patients suffering from benign or malignant neoplasms is a defect for which to provide an effective obturator is a difficult task for the maxillofacial prosthodontist. Multidisciplinary treatment planning is essential to achieve adequate retention and function for the prosthesis. Speech is often unintelligible as a result of the marked defects in articulation and nasal resonance. This paper describes how to achieve the goal for esthetics and phonetics and also describes the fabrication of a hollow obturator by two piece method, which is simple and maybe used as definitive obturator for maximum comfort of the patient.

  1. Gene expression changes and early events in cotton fibre development.

    Science.gov (United States)

    Lee, Jinsuk J; Woodward, Andrew W; Chen, Z Jeffrey

    2007-12-01

    Cotton is the dominant source of natural textile fibre and a significant oil crop. Cotton fibres, produced by certain species in the genus Gossypium, are seed trichomes derived from individual cells of the epidermal layer of the seed coat. Cotton fibre development is delineated into four distinct and overlapping developmental stages: fibre initiation, elongation, secondary wall biosynthesis and maturation. Recent advances in gene expression studies are beginning to provide new insights into a better understanding of early events in cotton fibre development. Fibre cell development is a complex process involving many pathways, including various signal transduction and transcriptional regulation components. Several analyses using expressed sequence tags and microarray have identified transcripts that preferentially accumulate during fibre development. These studies, as well as complementation and overexpression experiments using cotton genes in arabidopsis and tobacco, indicate some similar molecular events between trichome development from the leaf epidermis and fibre development from the ovule epidermis. Specifically, MYB transcription factors regulate leaf trichome development in arabidopsis and may regulate seed trichome development in cotton. In addition, transcript profiling and ovule culture experiments both indicate that several phytohormones and other signalling pathways mediate cotton fibre development. Auxin and gibberellins promote early stages of fibre initiation; ethylene- and brassinosteroid-related genes are up-regulated during the fibre elongation phase; and genes associated with calmodulin and calmodulin-binding proteins are up-regulated in fibre initials. Additional genomic data, mutant and functional analyses, and genome mapping studies promise to reveal the critical factors mediating cotton fibre cell development.

  2. Femtosecond laser processing of optical fibres for novel sensor development

    Science.gov (United States)

    Kalli, Kyriacos; Theodosiou, Antreas; Ioannou, Andreas; Lacraz, Amedee

    2017-04-01

    We present results of recent research where we have utilized a femtosecond laser to micro-structure silica and polymer optical fibres in order to realize versatile optical components such as diffractive optical elements on the fibre end face, the inscription of integrated waveguide circuits in the fibre cladding and novel optical fibre sensors designs based on Bragg gratings in the core. A major hurdle in tailoring or modifying the properties of optical fibres is the development of an inscription method that can prove to be a flexible and reliable process that is generally applicable to all optical fibre types; this requires careful matching of the laser parameters and optics in order to examine the spatial limits of direct laser writing, whether the application is structuring at the surface of the optical fibre or inscription in the core and cladding of the fibre. We demonstrate a variety of optical components such as two-dimensional grating structures, Bessel, Airy and vortex beam generators; moreover, optical bridging waveguides inscribed in the cladding of single-mode fibre as a means to selectively couple light from single-core to multi-core optical fibres, and demonstrate a grating based sensor; finally, we have developed a novel femtosecond laser inscription method for the precise inscription of tailored Bragg grating sensors in silica and polymer optical fibres. We also show that this novel fibre Bragg grating inscription technique can be used to modify and add versatility to an existing, encapsulated optical fibre pressure sensor.

  3. Barium Depletion in Hollow Cathode Emitters

    Science.gov (United States)

    Polk, James E.; Capece, Angela M.; Mikellides, Ioannis G.; Katz, Ira

    2009-01-01

    The effect of tungsten erosion, transport and redeposition on the operation of dispenser hollow cathodes was investigated in detailed examinations of the discharge cathode inserts from an 8200 hour and a 30,352 hour ion engine wear test. Erosion and subsequent re-deposition of tungsten in the electron emission zone at the downstream end of the insert reduces the porosity of the tungsten matrix, preventing the ow of barium from the interior. This inhibits the interfacial reactions of the barium-calcium-aluminate impregnant with the tungsten in the pores. A numerical model of barium transport in the internal xenon discharge plasma shows that the barium required to reduce the work function in the emission zone can be supplied from upstream through the gas phase. Barium that flows out of the pores of the tungsten insert is rapidly ionized in the xenon discharge and pushed back to the emitter surface by the electric field and drag from the xenon ion flow. This barium ion flux is sufficient to maintain a barium surface coverage at the downstream end greater than 0.6, even if local barium production at that point is inhibited by tungsten deposits. The model also shows that the neutral barium pressure exceeds the equilibrium vapor pressure of the impregnant decomposition reaction over much of the insert length, so the reactions are suppressed. Only a small region upstream of the zone blocked by tungsten deposits is active and supplies the required barium. These results indicate that hollow cathode failure models based on barium depletion rates in vacuum dispenser cathodes are very conservative.

  4. Mechanical Property Analysis on Sandwich Structured Hybrid Composite Made from Natural Fibre, Glass Fibre and Ceramic Fibre Wool Reinforced with Epoxy Resin

    Science.gov (United States)

    Bharat, K. R.; Abhishek, S.; Palanikumar, K.

    2017-06-01

    Natural fibre composites find wide range of applications and usage in the automobile and manufacturing industries. They find lack in desired properties, which are required for present applications. In current scenario, many developments in composite materials involve the synthesis of Hybrid composite materials to overcome some of the lacking properties. In this present investigation, two sandwich structured hybrid composite materials have been made by reinforcing Aloe Vera-Ceramic Fibre Wool-Glass fibre with Epoxy resin matrix and Sisal fibre-Ceramic Fibre Wool-Glass fibre with Epoxy resin matrix and its mechanical properties such as Tensile, Flexural and Impact are tested and analyzed. The test results from the two samples are compared and the results show that sisal fibre reinforced hybrid composite has better mechanical properties than aloe vera reinforced hybrid composite.

  5. Fatigue processes in thermoplastic fibres; Les mecanismes de fatigue dans les fibres thermoplastiques

    Energy Technology Data Exchange (ETDEWEB)

    Herrera Ramirez, J.M.

    2004-09-15

    The present study examines and compares the behaviour of the two types of PA66 fibres and two types of PET fibres under fatigue loading up to failure, and the correlation between the fibres (nano)structures and their structural heterogeneities, with fatigue lifetimes. Several techniques have been used to analyze the materials, such as scanning electron microscopy (SEM), microanalysis (EDS), differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD) and micro-Raman spectroscopy. A meticulous analysis by scanning electron microscopy of the fracture morphology of fibres broken in tension and in fatigue, as well as a study of the fatigue life, were undertaken. The fatigue process occurs when the cyclic load amplitude is sufficiently large, however a condition for fatigue failure is that the minimum load each cycle must be lower than a threshold stress level. Failure under fatigue conditions leads to distinctive fracture morphologies which are very different from those seen after tensile or creep failure and this allows easy identification of the fatigue process. The fibres have been analyzed in the as received state and after fatigue failure in order to observe the microstructural changes resulting from the fatigue loading. The results will be compared with those obtained for fibres loaded under conditions where the fatigue process was hindered. The role of the microstructure of the fibres in determining fatigue will be discussed in this work and the possibility of improving their resistance to fatigue or eliminating the fatigue process will be discussed. (author)

  6. Single fibre strength of cellulosic fibre extracted from "Belatlan roots" plant

    Science.gov (United States)

    M. Hanis. A., H.; Majid, M. S. Abdul; Ridzuan, M. J. M.; Fahmi, I.

    2017-12-01

    The tensile strength of a fibre extracted from "Belatlan Root" plant was investigated as potential reinforcement material in polymeric composites. Following retting process, the fibres were manually extracted from "Belatlan" root's plant. The fibres were treated with 5 % 10 %, 15 %, and 20 % sodium hydroxide (NaOH) wt. % concentration for 24 h. The single fibre tests were then performed in accordance with ASTM D3822-07 standard. The surfaces of the fibres prior and after the treatment were observed with a metallurgical Microscope MT8100 and the physical properties were recorded. Physically, in the post treatment, the fibre showed a decrease in diameter with increase in NaOH concentration The results from the mechanical testing indicates that samples subjected to 5 % NaOH treatment yielded the highest tensile strength and elastic modulus at 89.05 MPa ± 2.75 and 3.81 GPa ± 0.09 respectively compared to untreated fibres. This represents an increase of almost 72 % in tensile strength and 42 % for elastic modulus. The findings support the preliminary information for incorporating the "Belatlan Root" as possible reinforcing materials in composite structures.

  7. Investigation of digital light processing using fibre-reinforced polymers

    DEFF Research Database (Denmark)

    Hofstätter, Thomas; Pedersen, David Bue; Nielsen, Jakob Skov

    2016-01-01

    Literature research shows multiple applications of fibre-reinforced polymers (FRP) respectively in fused deposition modelling and gypsum printing influencing the quality of the products in terms of stress and strain resistance as well as flexibility. So far, applications of fibre......-reinforced polymers in digital light processing (DLP) are limited. Fibre-reinforced polymer composites were manufactured into test objects using digital light processing. Short fibres were used in an unordered manner. An anisotropic property due to fibre orientation within the material was observed. The importance...... of fibre length and shape compared to layer thickness has been investigated including concepts to circumvent clustering of the fibres.This research contributes to the implementation of fibre-reinforced polymers in additive manufacturing technologies. Digital light processing allows generation...

  8. Fibre-Optic Strain Measurement For Structural Integrity Monitoring

    NARCIS (Netherlands)

    Bruinsma, A.J.A.; Zuylen, P. van; Lamberts, C.W.; Krijger, A.J.T. de

    1984-01-01

    A method is demonstrated for monitoring the structural integrity of large structures, using an optical fibre. The strain distribution along the structure is monitored by measuring the attentuation of light along the length of the fibre.

  9. Short-fibre reinforcement of calcium phosphate bone cement.

    Science.gov (United States)

    Buchanan, F; Gallagher, L; Jack, V; Dunne, N

    2007-02-01

    Calcium phosphate cement (CPC) sets to form hydroxyapatite, a major component of mineral bone, and is gaining increasing interest in bone repair applications. However, concerns regarding its brittleness and tendency to fragment have limited its widespread use. In the present study, short-fibre reinforcement of an apatitic calcium phosphate has been investigated to improve the fracture behaviour. The fibres used were polypropylene (PP) fibres, 50 microm in diameter and reduced in length by cryogenic grinding. The compressive strength and fracture behaviour were examined. Fibre addition of up to 10 wt % had a significant effect on composite properties, with the energy absorbed during failure being significantly increased, although this tended to be accompanied with a slight drop in compressive strength. The fibre reinforcement mechanisms appeared to be crack bridging and fibre pull-out. The setting time of the CPC with fibre reinforcement was also investigated and was found to increase with fibre volume fraction.

  10. Sugarcane fibre may prevents hairball formation in cats

    National Research Council Canada - National Science Library

    Loureiro, Bruna A; Sembenelli, Guilherme; Maria, Ana P J; Vasconcellos, Ricardo S; Sá, Fabiano C; Sakomura, Nilva K; Carciofi, Aulus C

    2014-01-01

    .... It is believed that dietary fibre might reduce formation of these trichobezoars (hairballs). The effects of two insoluble fibre sources added to kibble diets were evaluated with respect to trichobezoar faecal excretion...

  11. Fractographic observations of the microstructural characteristics of flax fibre composites

    DEFF Research Database (Denmark)

    Madsen, Bo; Asian, Mustafa; Lilholt, Hans

    2016-01-01

    failure followed by longitudinal splitting. For the thermoplastic matrix, concentric rings with different points of origin are observed in the matrix regions of the composite fracture surface. The concentric rings have a microporous structure consisting of nanoscale polymer fibrils. The concentring rings...... flax fibre/thermoplastic composites are presented. The findings are presented in relation to the three operational parts in composites: fibres, matrix and fibre/matrix interface. For the flax fibres, the striated structure on the fibre surface is shown to consist of cellulose macrofibrils oriented...... form mirror zones with no riverlines, followed by repeated mist and hackle zones with distinct radiating riverlines. For the flax fibre/thermoplastic matrix interface, microscale imprints of whole fibres, and nanoscale imprints of fibre surface structures are observed on the matrix surface...

  12. Ductile behavior of polyethylene fibre reinforced geopolymer composite

    Directory of Open Access Journals (Sweden)

    Ahmed Shaikh Faiz Uddin

    2017-01-01

    Full Text Available This paper presents the effects of various volume fractions of polyethylene (PE fibres of 0.5%, 1%, 1.5% and 2% on tensile, flexure and compressive behavior of PE fibres reinforced geopolymer composites (PE-FRGC. Results show that the 1% PE fibre by volume is the optimum fibre volume fraction for fly ash geopolymer composite, which exhibit superior strain and deflection hardening behavior in uni-axial tension and three-point bending, respectively. Results also show that the compressive strength of the composites decreases with increase in volume fractions of PE fibre. The fibre surface examination of PE fibre in the gopolymer matrix using scanning electron microscope (SEM and energy dispersive spectroscopy (EDS revealed no significant damage of PE fibre in the alkaline geopolymer matrix.

  13. Presynaptic calcium signalling in cerebellar mossy fibres

    DEFF Research Database (Denmark)

    Thomsen, Louiza Bohn; Jörntell, Henrik; Midtgaard, Jens

    2010-01-01

    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....... 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...

  14. Mechanical losses in thin fused silica fibres

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-03-07

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

  15. Turbulence hierarchy in a random fibre laser.

    Science.gov (United States)

    González, Iván R Roa; Lima, Bismarck C; Pincheira, Pablo I R; Brum, Arthur A; Macêdo, Antônio M S; Vasconcelos, Giovani L; de S Menezes, Leonardo; Raposo, Ernesto P; Gomes, Anderson S L; Kashyap, Raman

    2017-05-31

    Turbulence is a challenging feature common to a wide range of complex phenomena. Random fibre lasers are a special class of lasers in which the feedback arises from multiple scattering in a one-dimensional disordered cavity-less medium. Here we report on statistical signatures of turbulence in the distribution of intensity fluctuations in a continuous-wave-pumped erbium-based random fibre laser, with random Bragg grating scatterers. The distribution of intensity fluctuations in an extensive data set exhibits three qualitatively distinct behaviours: a Gaussian regime below threshold, a mixture of two distributions with exponentially decaying tails near the threshold and a mixture of distributions with stretched-exponential tails above threshold. All distributions are well described by a hierarchical stochastic model that incorporates Kolmogorov's theory of turbulence, which includes energy cascade and the intermittence phenomenon. Our findings have implications for explaining the remarkably challenging turbulent behaviour in photonics, using a random fibre laser as the experimental platform.

  16. Current Impact Of Fibre Optic Sensors

    Science.gov (United States)

    McGeehin, Peter

    1987-10-01

    Technical and commercial factors important in assessing the impact of fibre optic sensors are considered, and concluded to be of especial importance for the military/aerospace/defence applications areas, Significant growth potential is anticipated, but previous work has not acknowledged the highly fragmented nature of the applications sectors, which are described, The current market for fibre optic sensors is compared with the electro-optics industry in Japan, and applications of electro-optic instrumentation in manufacturing, The work of the UK Optical Sensors Collaborative Association is described as a realistic response for the process/industrial sectors, It is concluded that the technology of fibre optic sensors has not progressed beyond user evaluation of early products, and in spite of the fragmented nature of the industrial and medical areas, growth potential in selected niches shows potential, The technology is particularly strong in the aerospace/defence sector,

  17. Space Division Multiplexing in Optical Fibres

    CERN Document Server

    Richardson, D J; Nelson, L E

    2013-01-01

    Optical communications technology has made enormous and steady progress for several decades, providing the key resource in our increasingly information-driven society and economy. Much of this progress has been in finding innovative ways to increase the data carrying capacity of a single optical fibre. In this search, researchers have explored (and close to maximally exploited) every available degree of freedom, and even commercial systems now utilize multiplexing in time, wavelength, polarization, and phase to speed more information through the fibre infrastructure. Conspicuously, one potentially enormous source of improvement has however been left untapped in these systems: fibres can easily support hundreds of spatial modes, but today's commercial systems (single-mode or multi-mode) make no attempt to use these as parallel channels for independent signals.

  18. Development of SERS active fibre sensors

    CERN Document Server

    Polwart, E

    2002-01-01

    Surface-enhanced Raman scattering (SERS) is sensitive and selective and when coupled with fibre-optics could potentially produce an effective chemical sensing system. This thesis concerns the development of a single-fibre-based sensor, with an integral SERS-active substrate. A number of different methods for the manufacture of SERS-active surfaces on glass substrates were investigated and compared. The immobilisation of metal nanoparticles on glass functionalised with (3-aminopropyl)trimethoxysilane emerged as a suitable approach for the production of sensors. Substrates prepared by this approach were characterised using UV-visible spectroscopy, electron microscopy and Raman mapping. It was found that exposure of substrates to laser radiation led to a decrease in the signal recorded from adsorbed analytes. This speed of the decrease was shown to depend on the analyte, and the exciting wavelength and power. SERS-active fibre sensors were produced by immobilisation of silver nanoparticles at the distal end of a...

  19. Nonlinear optics of fibre event horizons.

    Science.gov (United States)

    Webb, Karen E; Erkintalo, Miro; Xu, Yiqing; Broderick, Neil G R; Dudley, John M; Genty, Goëry; Murdoch, Stuart G

    2014-09-17

    The nonlinear interaction of light in an optical fibre can mimic the physics at an event horizon. This analogue arises when a weak probe wave is unable to pass through an intense soliton, despite propagating at a different velocity. To date, these dynamics have been described in the time domain in terms of a soliton-induced refractive index barrier that modifies the velocity of the probe. Here we complete the physical description of fibre-optic event horizons by presenting a full frequency-domain description in terms of cascaded four-wave mixing between discrete single-frequency fields, and experimentally demonstrate signature frequency shifts using continuous wave lasers. Our description is confirmed by the remarkable agreement with experiments performed in the continuum limit, reached using ultrafast lasers. We anticipate that clarifying the description of fibre event horizons will significantly impact on the description of horizon dynamics and soliton interactions in photonics and other systems.

  20. Laser acceleration... now with added fibre

    CERN Multimedia

    Katarina Anthony

    2012-01-01

    Laser acceleration technology is plagued by two main issues: efficiency and repetition rates. In other words, lasers consume too much power and cannot sustain accelerating particles long enough to produce collisions. ICAN, a new EU-funded project, is examining how fibre lasers may help physicists tackle these issues.   A diode-pumped fibre laser. (Image courtesy of Laser Zentrum Hannover.) The International Coherent Amplification Network (ICAN) is studying the potential of lasers for collision physics. CERN is a beneficiary of the project and will collaborate with 15 other institutes from around the world, including KEK in Japan, Fermilab in the USA, and DESY in Germany. “The network is looking into existing fibre laser technology, which we believe has fantastic potential for accelerators,” says Gerard Mourou, ICAN co-ordinator at the École Polytechnique in France. “The hope is to make laser acceleration competitive with traditional radio-fre...

  1. Enhancement of Spartium junceum L. fibres properties

    Science.gov (United States)

    Kovačević, Z.; Bischof, S.; Antonović, A.

    2017-10-01

    Properties of lignocellulosic Spartium junceum L. (SJL) fibres were investigated in order to use them as reinforcement in composite material production. The fibres were obtained by microwave maceration process and additionally modified with NaOH, nanoclay and citric acid with the aim to improve their mechanical, thermal and other physical-chemical properties. Tensile and thermal properties of these natural fibres were enhanced by the different modification treatment which is investigated by the Vibrodyn/Vibroskop method and thermogravimetric analysis (TGA), whilst determination of chemical composition and fibre’s surface properties were explored using scanning electron microscope (SEM), electron dispersive spectroscopy (EDS) and elektrokinetic analyser. All the results show great improvement of nanoclay/citric acid modified SJL properties.

  2. Broad-band robustly single-mode hollow-core PCF by resonant filtering of higher order modes

    CERN Document Server

    Günendi, Mehmet C; Frosz, Michael H; Russell, Philip St J

    2015-01-01

    We propose and theoretically analyse a novel hollow-core photonic crystal fibre (PCF) that is engineered so as to strongly suppress higher order modes, i.e., to provide robust LP$_{01}$ single-mode guidance in all the wavelength ranges where the fibre guides with low loss. Encircling the core is a single ring of non-touching glass elements whose modes are tailored to ensure resonant phase-matched coupling to higher-order core modes, causing them to leak at a very high rate into the supporting solid glass sheath. Using a model based on coupled capillary waveguides, as well as full vectorial finite element modelling, we show that this modal filtering effect depends on only one dimensionless geometrical parameter, akin to the well-known $d/{\\Lambda}$ parameter for endlessly single-mode solid-core PCF. The design is scalable up to large core sizes and is predicted to deliver LP$_{01}$ mode losses of some $10$s of dB/km in multiple transmission windows, the broadest of which spans more than an octave. At the same ...

  3. Optical fibre dosemeter systems for clinical applications based on radioluminescence and optically stimulated luminescence from Al2O3:C

    DEFF Research Database (Denmark)

    Marckmann, C.J.; Andersen, C.E.; Aznar, M.C.

    2006-01-01

    Optical fibre dosemeter systems based on radioluminescence and optically stimulated luminescence (OSL) from carbon-doped aluminium oxide (Al2O3:C) crystals were developed for in vivo real-time dose rate and absorbed dose measurements in radiotherapy and mammography. A technique was also developed...... for making ultra-small dosemeter probes that can easily be placed inside patients in radiation treatment. These probes have shown excellent properties in both head and neck intensity-modulated radiation therapy treatment and in mammography. The dose-response of the OSL signal for the new optical fibre...

  4. Synthesis, characterization and properties of hollow nickel phosphide nanospheres

    Energy Technology Data Exchange (ETDEWEB)

    Ni Yonghong; Tao Ali; Hu Guangzhi; Cao Xiaofeng; Wei Xianwen; Yang Zhousheng [College of Chemistry and Materials Science, Anhui Key Laboratory of Functional Molecular Solids, Anhui Normal University, Wuhu 241000 (China)

    2006-10-14

    Nickel phosphide (Ni{sub 12}P{sub 5}) hollow nanospheres with a mean diameter of 100 nm and a shell thickness of 15-20 nm have been successfully prepared by a hydrothermal-microemulsion route, using NaH{sub 2}PO{sub 2} as a phosphorus source. XRD, EDS (HR)TEM, SEM and the SAED pattern were used to characterize the final product. Experiments showed that the as-prepared nickel phosphide hollow nanospheres could selectively catalytically degrade some organic dyes such as methyl red and Safranine T under 254 nm UV light irradiation. At the same time, the nickel phosphide hollow nanospheres showed a stronger ability to promote electron transfer between the glass-carbon electrode and adrenalin than nickel phosphide honeycomb-like particles prepared by a simple hydrothermal route. A possible formation process for nickel phosphide hollow nanospheres was suggested based on the experimental results.

  5. Hollow Au–Ag Alloy Nanorices and Their Optical Properties

    Directory of Open Access Journals (Sweden)

    Keke Yu

    2017-09-01

    Full Text Available Hollow noble metal nanoparticles have excellent performance not only in surface catalysis but also in optics. In this work, the hollow Au–Ag alloy nanorices are fabricated by the galvanic replacement reaction. The dark-field spectrum points out that there is a big difference in the optical properties between the pure Ag nanorices and the hollow alloy nanorices that exhibit highly tunable localized surface plasmon resonances (LSPR and that possess larger radiative damping, which is also indicated by the finite element method. Furthermore, the surface enhanced Raman scattering (SERS and oxidation test indicate that hollow Au–Ag alloy nanorices show good anti-oxidation and have broad application prospects in surface-plasmon-related fields.

  6. Polyazole hollow fiber membranes for direct contact membrane distillation

    KAUST Repository

    Maab, Husnul

    2013-08-07

    Porous hollow fiber membranes were fabricated from fluorinated polyoxadiazole and polytriazole by a dry-wet spinning method for application in desalination of Red Sea water by direct contact membrane distillation (DCMD). The data were compared with commercially available hollow fiber MD membranes prepared from poly(vinylidene fluoride). The membranes were characterized by electron microscopy, liquid entry pressure (LEP), and pore diameter measurements. Finally, the hollow fiber membranes were tested for DCMD. Salt selectivity as high as 99.95% and water fluxes as high as 35 and 41 L m -2 h-1 were demonstrated, respectively, for polyoxadiazole and polytriazole hollow fiber membranes, operating at 80 C feed temperature and 20 C permeate. © 2013 American Chemical Society.

  7. Spatial light modulation for mode conditioning

    DEFF Research Database (Denmark)

    Glückstad, Jesper; Palima, Darwin

    We demonstrate patented techniques for generating tuneable complex field distributions for controllable coupling to high-order guided modes of micro-structured fibres. The optical Fourier transform of binary phase-only patterns which are encoded on a computer-controlled spatial light modulator...

  8. FOAM CONCRETE REINFORCEMENT BY BASALT FIBRES

    Directory of Open Access Journals (Sweden)

    Zhukov Aleksey Dmitrievich

    2012-10-01

    Full Text Available The authors demonstrate that the foam concrete performance can be improved by dispersed reinforcement, including methods that involve basalt fibres. They address the results of the foam concrete modeling technology and assess the importance of technology-related parameters. Reinforcement efficiency criteria are also provided in the article. Dispersed reinforcement improves the plasticity of the concrete mix and reduces the settlement crack formation rate. Conventional reinforcement that involves metal laths and rods demonstrates its limited application in the production of concrete used for thermal insulation and structural purposes. Dispersed reinforcement is preferable. This technology contemplates the infusion of fibres into porous mixes. Metal, polymeric, basalt and glass fibres are used as reinforcing components. It has been identified that products reinforced by polypropylene fibres demonstrate substantial abradability and deformability rates even under the influence of minor tensile stresses due to the low adhesion strength of polypropylene in the cement matrix. The objective of the research was to develop the type of polypropylene of D500 grade that would demonstrate the operating properties similar to those of Hebel and Ytong polypropylenes. Dispersed reinforcement was performed by the basalt fibre. This project contemplates an autoclave-free technology to optimize the consumption of electricity. Dispersed reinforcement is aimed at the reduction of the block settlement in the course of hardening at early stages of their operation, the improvement of their strength and other operating properties. Reduction in the humidity rate of the mix is based on the plasticizing properties of fibres, as well as the application of the dry mineralization method. Selection of optimal parameters of the process-related technology was performed with the help of G-BAT-2011 Software, developed at Moscow State University of Civil Engineering. The authors also

  9. Trace elements in hazardous mineral fibres.

    Science.gov (United States)

    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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Steel fibre corrosion in cracks:durability of sprayed concrete

    OpenAIRE

    Nordström, Erik

    2000-01-01

    Steel fibre reinforced sprayed concrete is common practice for permanent linings in underground construction. Today there is a demand on "expected technical service life" of 120 years. Thin steel fibres could be expected to discontinue carrying load fast with a decrease of fibre diameter caused by corrosion, especially in cracks. The thesis contains results from inspections on existing sprayed concrete structures and a literature review on corrosion of steel fibres in cracked concrete. To stu...

  11. Photonic Crystal Fibres - the State-of-the-Art

    DEFF Research Database (Denmark)

    Bjarklev, Anders Overgaard; Hansen, K. P.; Hansen, Theis Peter

    2002-01-01

    Photonic crystal fibres having microstructured air-silica cross sections offer new optical properties compared to conventional fibres. These include novel guiding mechanisms, unique spectral properties and nonlinear possibilities. Recent results within the field are reviewed.......Photonic crystal fibres having microstructured air-silica cross sections offer new optical properties compared to conventional fibres. These include novel guiding mechanisms, unique spectral properties and nonlinear possibilities. Recent results within the field are reviewed....

  12. Radiotherapy dosimetry based on plastic optical fibre sensors

    Science.gov (United States)

    O'Keeffe, S.; Grattan, M.; Hounsell, A.; McCarthy, D.; Woulfe, P.; Cronin, J.; Lewis, E.

    2013-05-01

    The use of a PMMA based plastic optical fibre in radiotherapy dosimetry is presented. The optical fibre tip is coated with a scintillation material, terbium-doped gadolinium oxysulfide (Gd2O2S:Tb), which fluoresces under ionising radiation. The emitted signal penetrates the fibre and propagates along the fibre where it is remotely monitored using a fluorescence spectrometer. The results demonstrate good repeatability, with a maximum percentage error of 0.59% and the response is independent of dose rate.

  13. Zeonex Microstructured Polymer Optical Fibre Bragg Grating Sensor

    DEFF Research Database (Denmark)

    Woyessa, Getinet; Fasano, Andrea; Markos, Christos

    2016-01-01

    We fabricated an endlessly single mode and humidity insensitive Zeonex microstructured polymer optical fibre (mPOF) for fibre Bragg grating (FBG) temperature and strain sensors. We inscribed and characterise FBGs in Zeonex mPOF for the first time.......We fabricated an endlessly single mode and humidity insensitive Zeonex microstructured polymer optical fibre (mPOF) for fibre Bragg grating (FBG) temperature and strain sensors. We inscribed and characterise FBGs in Zeonex mPOF for the first time....

  14. Review on hygroscopic aging of cellulose fibres and their biocomposites

    CSIR Research Space (South Africa)

    Mokhothu, Thabang h

    2015-06-01

    Full Text Available . Emphasis is placed on possible solutions to bridge the gap between chemical 130 treatments, bio-based coatings and developing superhydrophobic materials using 131 nanoparticles to improve the long-term utilization of fibre reinforced composites... into the microcracks and other forms of micro damages. Moisture absorption behaviour 321 is observed when the fibre-polymer composite is exposed to moisture, the polar nature of 322 fibres, causes the fibre to absorb water and swell. As a result, the dilapidation...

  15. Multifunctional non-woven fabrics of interfused graphene fibres

    OpenAIRE

    Li, Zheng; Xu, Zhen; Liu, Yingjun; Wang, Ran; Gao, Chao

    2016-01-01

    Carbon-based fibres hold promise for preparing multifunctional fabrics with electrical conductivity, thermal conductivity, permeability, flexibility and lightweight. However, these fabrics are of limited performance mainly because of the weak interaction between fibres. Here we report non-woven graphene fibre fabrics composed of randomly oriented and interfused graphene fibres with strong interfibre bonding. The all-graphene fabrics obtained through a wet-fusing assembly approach are porous a...

  16. A Fibre Bragg Grating Interrogation Technique Based on High Birefringence Fibre Loop Mirror and WDM

    Directory of Open Access Journals (Sweden)

    Zhang Xun

    2016-01-01

    Full Text Available In this paper, a fibre Bragg grating (FBG interrogation technique based on high Birefringence fibre loop mirror (Hi-Bi FLM and wavelength division multiplexer (WDM is proposed and demonstrated. The approximate linear edge of the transmittance of the Hi-Bi FLM, which is a sinusoidal function of wavelength, is used to interrogate the sensing FBGs and WDMs is used to realize wavelength discrimination .Suitable for both static and dynamic sensing, this interrogation method has the advantages of all fibre design and high stability.

  17. Laser-plasma-based linear collider using hollow plasma channels

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, C.B., E-mail: CBSchroeder@lbl.gov; Benedetti, C.; Esarey, E.; Leemans, W.P.

    2016-09-01

    A linear electron–positron collider based on laser-plasma accelerators using hollow plasma channels is considered. Laser propagation and energy depletion in the hollow channel is discussed, as well as the overall efficiency of the laser-plasma accelerator. Example parameters are presented for a 1-TeV and 3-TeV center-of-mass collider based on laser-plasma accelerators.

  18. Thin-walled reinforcement lattice structure for hollow CMC buckets

    Energy Technology Data Exchange (ETDEWEB)

    de Diego, Peter

    2017-06-27

    A hollow ceramic matrix composite (CMC) turbine bucket with an internal reinforcement lattice structure has improved vibration properties and stiffness. The lattice structure is formed of thin-walled plies made of CMC. The wall structures are arranged and located according to high stress areas within the hollow bucket. After the melt infiltration process, the mandrels melt away, leaving the wall structure to become the internal lattice reinforcement structure of the bucket.

  19. Flat Bunches with a Hollow Distribution for Space Charge Mitigation

    CERN Document Server

    Oeftiger, Adrian; Findlay, Alan James; Hancock, Steven; Rumolo, Giovanni

    2016-01-01

    Longitudinally hollow bunches provide one means to mitigate the impact of transverse space charge. The hollow distributions are created via dipolar parametric excitation during acceleration in CERN's Proton Synchrotron Booster. We present simulation work and beam measurements. Particular emphasis is given to the alleviation of space charge effects on the long injection plateau of the downstream Proton Synchrotron machine, which is the main goal of this study.

  20. Highly efficient fluorescence sensing with hollow core photonic crystal fibers

    DEFF Research Database (Denmark)

    Smolka, Stephan; Barth, Michael; Benson, Oliver

    2008-01-01

    We investigate hollow core photonic crystal fibers for ultra-sensitive fluorescence detection by selectively infiltrating the central hole with fluorophores. Dye concentrations down to 10(-9) M can be detected using only nanoliter sample volumes.......We investigate hollow core photonic crystal fibers for ultra-sensitive fluorescence detection by selectively infiltrating the central hole with fluorophores. Dye concentrations down to 10(-9) M can be detected using only nanoliter sample volumes....

  1. Liquid Temperature Measurements Using Two Different Tunable Hollow Prisms.

    Science.gov (United States)

    Calixto, Sergio; Rosete-Aguilar, Martha; Torres-Gomez, Ismael

    2017-01-29

    This paper describes the design, fabrication, and testing of two hollow prisms. One is a prism with a grating glued to its hypotenuse. This ensemble, prism + grating, is called a grism. It can be applied as an on-axis tunable spectrometer. The other hollow prism is a constant deviation one called a Pellin-Broca. It can be used as a tunable dispersive element in a spectrometer with no moving parts. The application of prisms as temperature sensors is shown.

  2. 3D hollow nanostructures as building blocks for multifunctional plasmonics

    KAUST Repository

    De Angelis, Francesco De

    2013-08-14

    We present an advanced and robust technology to realize 3D hollow plasmonic nanostructures which are tunable in size, shape, and layout. The presented architectures offer new and unconventional properties such as the realization of 3D plasmonic hollow nanocavities with high electric field confinement and enhancement, finely structured extinction profiles, and broad band optical absorption. The 3D nature of the devices can overcome intrinsic difficulties related to conventional architectures in a wide range of multidisciplinary applications. © 2013 American Chemical Society.

  3. Benign Fibröz Histiositoma

    OpenAIRE

    ÖĞÜTCEN TOLLER, Melahat; ÖZKAN, Nilüfer; YILDIZ, Levent

    2015-01-01

    Benign fibröz histiositoma (BFH), ağız kavitesinde nadir görülen, klinik ve histopatolojik olarak teşhiste karışıklığa yol açan bir tümördür. Bu makalede, sağ mandibular bukkal bölgede görülen bir benign fibröz histiositoma vakası sunularak, klinik ve histopatolojik özellikleri tartışıldı.

  4. Photonic crystal fibres with large nonlinear coefficients

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper; Bjarklev, Anders Overgaard

    2004-01-01

    We investigate the upper limits on the nonlinear coefficients obtainable in various silica-based photonic crystal fibre designs. For a fixed wavelength, the highest nonlinearities are found to occur when a substantial part of the field energy resides in air. The case of a silica strand in air...... is found to constitute an upper bound on the nonlinear coefficients obtained; however, all the designs investigated allow nonlinear coefficients larger than 50% of this limiting value. On the other hand, the choice of fibre design is found to have a significant influence on the dispersion properties....

  5. Work on optical fibres in Russia

    Science.gov (United States)

    Semjonov, S. L.

    2017-12-01

    The Sixth All-Russia Conference on Fibre Optics (ARCFO-2017) was held in Perm on 3–6 October 2017. The previous conferences were held in 2007, 2009, 2011, 2013 and 2015, also in Perm. Organised by the Fiber Optics Research Center (FORC), Russian Academy of Sciences, and the Perm Research and Production Instrument Company (PRPIC) and supported by the Perm National Research Polytechnic University (PNRPU) and Perm State University (PSU), ARCFO-2017 was a key scientific and technological event in the field of photonics, stimulating the development of fibre optics and adjacent areas of research in Russia.

  6. Sources laser femtoseconde à fibre optique

    OpenAIRE

    Hanna, Marc

    2013-01-01

    Les sources laser à fibre sont de plus en plus utilisées dans des domaines très divers car elles possèdent des avantages majeurs : qualité de faisceau, intégration, possibilité d'émettre une puissance moyenne élevée, efficacité, robustesse. Nous présentons des travaux de recherche visant à étendre les performances des sources ultrarapides basées sur les fibres en utilisant des effets d'optique non linéaire et en proposant de nouvelles architectures laser.

  7. A statistical analysis of fibre size and shape distribution after compounding in composites reinforced by natural fibres

    NARCIS (Netherlands)

    Moigne, Le N.; Oever, van den M.J.A.; Budtova, T.

    2011-01-01

    Using high resolution optical microscopy coupled with image analysis software and statistical methods, fibre length and aspect ratio distributions in polypropylene composites were characterized. Three types of fibres, flax, sisal and wheat straw, were studied. Number and surface weighted

  8. A textile fibre survey as an aid to the interpretation of fibre evidence in the Sydney region.

    Science.gov (United States)

    Cantrell, S; Roux, C; Maynard, P; Robertson, J

    2001-11-15

    Frequency figures of the fibre population on textile cinema seats were measured in Sydney, Australia, in winter. Sixteen seats were analysed from a very popular cinema complex, with 3025 fibres classified according to colour, generic class and fluorescence properties (100 grey-black cotton fibres only). The recovered fibres were mostly natural fibres (84%) with cotton the most common generic type (70%). On the contrary, man made fibres were relatively rare (15%) with rayon constituting the majority of these (51%). The most common colour/generic class combinations were grey-black cotton (33%) and blue cotton (30%) accounting for 63% of the total population. All other frequencies were below 5%, most below 1% using only the two properties of colour and generic class. Fluorescence properties were found to be very discriminating as far as grey-black cotton fibres were concerned. These features are considered and discussed and in particular, to emphasise the significance of fibres as evidence of contact.

  9. Systems with Higher-Order Modulation

    Science.gov (United States)

    Seimetz, Matthias

    With the objective of reducing costs per information bit in optical communication networks, per fibre capacities and optical transparent transmission lengths have been stepped up by the introduction of new technology in recent years. The innovation of the erbium-doped fibre amplifier (EDFA) at the beginning of the nineties facilitated long distances to be bridged without electro-optical conversion. Wavelength division multiplexing (WDM) technology allowed a lot of wavelength channels to be simultaneously transmitted over one fibre and to be amplified by one EDFA with high bandwidth, offering a huge network capacity. At this time, the modulation format of choice was the simple "on-off keying" (OOK), and there was no need for increasing spectral efficiency. The internet traffic growth during the nineties required increasing transmission rates. In that context, the transmission impairments of the optical fibre had to be counteracted and the application of differential binary phased shift keying (DBPSK) became an issue, providing for a higher robustness against nonlinear effects [1]. Moreover, the transmission behaviour of binary intensity modulation was optimized by using alternative optical pulse shapes such as return to zero (RZ) and by employing schemes with auxiliary phase coding, such as optical duobinary, which exhibits a higher tolerance against chromatic dispersion (CD). The capacity-distance product was further enhanced by applying optical dispersion compensation, Raman amplification and advanced optical fibres, as well as through electronic means, such as forward error correction (FEC) and the adaptive compensation of CD and polarization mode dispersion (PMD).

  10. Interaction of solitary pulses in single mode optical fibres | Usman ...

    African Journals Online (AJOL)

    Interaction of solitary pulses in single mode optical fibres. A Usman, J Osman, DR Tilley. Abstract. We attempt to classify interaction of nonlinear optical pulses that propagate in form of solitary waves in single made optical fibres. Two solitary waves launched, by way of incidence, into an optical fibre from a single pulse if the ...

  11. Surface charges in blending short fibres with polyethylene powder

    NARCIS (Netherlands)

    Hofste, JM; Kersten, MJE; van Turnhout, J; Pennings, AJ

    1998-01-01

    Short fibres and ultra-high molecular weight polyethylene (UHMWPE) powder were mixed by swirling in a glass jar with compressed nitrogen. It was found that a kind of attraction between the fibres and UHMWPE particles is crucial for making a composite with a proper fibre distribution. If aramid and

  12. Environmental impact assessment of man-made cellulose fibres

    NARCIS (Netherlands)

    Shen, L.; Worrell, E.; Patel, M.K.

    2010-01-01

    Man-made cellulose fibres have played an important role in the production of textile products for more than 70 years. The purpose of this study is to assess the environmental impact of man-made cellulose fibres. Life cycle assessment (LCA) was conducted for three types of fibres (i.e. Viscose, Modal

  13. Distribution of Elastic Fibres in the Human Abdominal Linea Alba ...

    African Journals Online (AJOL)

    The linea alba (LA) supports biomechanical stress generated by intra-abdominal pressure. It is believed to contain connective tissue fibres, which provide tensile strength and pliancy. Previous studies have dwelt on collagen fibres with scarce reports on elastic fibres. Biomechanical studies have shown that the LA has ...

  14. Effects of dietary fibre on behaviour and satiety in pigs

    NARCIS (Netherlands)

    Leeuw, de J.A.; Bolhuis, J.E.; Bosch, G.; Gerrits, W.J.J.

    2008-01-01

    During the past decades there has been considerable interest in the use of dietary fibre in both animal and human nutrition. In human subjects dietary fibre has been studied intensively for possible effects on body-weight management and health. In animal nutrition the interest in dietary fibre has

  15. Femtosecond pulse generation and amplification in Yb-doped fibre ...

    Indian Academy of Sciences (India)

    mode-locking regimes are reviewed and the details of development and characterization of an all-fibre, high-power, ... components. Keywords. All-fibre amplifier; femtosecond pulse; chirped pulse amplification; mode- ... emerging as a promising candidate for high-power all-fibre integrated oscillator– amplifier system which ...

  16. Mechanical properties of short-flax-fibre reinforced compounds

    NARCIS (Netherlands)

    Bos, H.L.; Müssig, J.; Oever, van den M.J.A.

    2006-01-01

    The mechanical properties of flax/polypropylene compounds, manufactured both with a batch kneading and an extrusion process were determined and compared with the properties of Natural fibre Mat Thermoplastic (NMT) composites. The fibre length and width distributions of the fibres from the compounds

  17. 214 VARIATIONS IN THE FIBRE LENGTH OF RUBBER WOOD ...

    African Journals Online (AJOL)

    2010-09-02

    Sep 2, 2010 ... Makurdi Benue State. Correspondence: greenwatchinitiative@yahoo.com. ABSTRACT. Variations in the fibre length of rubber wood were investigated to determine suitability of the wood fibres for some industrial utilization. The fibre lengths were sampled according to main effects such as plantations effects ...

  18. GLASS-FIBRE REINFORCED COMPOSITES: THE EFFECT OF ...

    African Journals Online (AJOL)

    HOD

    tensile strength when compared with the neat resin and other oriented (G10E30) fibre reinforced composite. Similar observations were also noticed on the impact strength of these composites which signify the improved mechanical properties of oriented reinforced composite materials. Keywords: glass fibre, orientation, fibre ...

  19. Optical fibre Bragg grating recorded in TOPAS cyclic olefin copolymer

    DEFF Research Database (Denmark)

    Johnson, I.P.; Yuan, Scott Wu; Stefani, Alessio

    2011-01-01

    A report is presented on the inscription of a fibre Bragg grating into a microstructured polymer optical fibre fabricated from TOPAS cyclic olefin copolymer. This material offers two important advantages over poly (methyl methacrylate), which up to now has formed the basis for polymer fibre Bragg...

  20. Fabrication of silicon based glass fibres for optical communication

    Indian Academy of Sciences (India)

    Silicon based glass fibres are fabricated by conventional fibre drawing process. First, preform fabrication is carried out by means of conventional MCVD technique by using various dopants such as SiCl4, GeCl4, POCl3, and FeCl3. The chemicals are used in such a way that step index single mode fibre can be drawn.