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Sample records for carbon fibre tips

  1. Applications for carbon fibre recovered from composites

    NASA Astrophysics Data System (ADS)

    Pickering; Liu, Z.; Turner, TA; Wong, KH

    2016-07-01

    Commercial operations to recover carbon fibre from waste composites are now developing and as more recovered fibre becomes available new applications for recovered fibre are required. Opportunities to use recovered carbon fibre as a structural reinforcement are considered involving the use of wet lay processes to produce nonwoven mats. Mats with random in-plane fibre orientation can readily be produced using existing commercial processes. However, the fibre volume fraction, and hence the mechanical properties that can be achieved, result in composites with limited mechanical properties. Fibre volume fractions of 40% can be achieved with high moulding pressures of over 100 bar, however, moulding at these pressures results in substantial fibre breakage which reduces the mean fibre length and the properties of the composite manufactured. Nonwoven mats made from aligned, short carbon fibres can achieve higher fibre volume fractions with lower fibre breakage even at high moulding pressure. A process for aligning short fibres is described and a composite of over 60% fibre volume fraction has been manufactured at a pressures up to 100 bar with low fibre breakage. Further developments of the alignment process have been undertaken and a composite of 46% fibre volume fraction has been produced moulded at a pressure of 7 bar in an autoclave, exhibiting good mechanical properties that compete with higher grade materials. This demonstrates the potential for high value applications for recovered carbon fibre by fibre alignment.

  2. Super-tough carbon-nanotube fibres

    NASA Astrophysics Data System (ADS)

    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.

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

    SciTech Connect

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

    2014-01-01

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

  4. Radiation curing of carbon fibre composites

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

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

  5. Carbon fibre slotted waveguide arrays

    NASA Astrophysics Data System (ADS)

    Wagner, R.

    Spaceborne SARs call for antennas of large aperture and high structural performance; attention is accordingly given to the slotted waveguide antenna concept, which yields high aperture efficiency, good beam-shaping, and low losses in conjunction with great compactness and high stiffness. A distinctive technology for the manufacture of such waveguides from metallized carbon fiber-reinforced plastics, as well as for the construction of radiating arrays for such waveguides, is presented.

  6. A Dual Sensor for pH and Hydrogen Peroxide Using Polymer-Coated Optical Fibre Tips

    PubMed Central

    Purdey, Malcolm S.; Thompson, Jeremy G.; Monro, Tanya M.; Abell, Andrew D.; Schartner, Erik P.

    2015-01-01

    This paper demonstrates the first single optical fibre tip probe for concurrent detection of both hydrogen peroxide (H2O2) concentration and pH of a solution. The sensor is constructed by embedding two fluorophores: carboxyperoxyfluor-1 (CPF1) and seminaphtharhodafluor-2 (SNARF2) within a polymer matrix located on the tip of the optical fibre. The functionalised fibre probe reproducibly measures pH, and is able to accurately detect H2O2 over a biologically relevant concentration range. This sensor offers potential for non-invasive detection of pH and H2O2 in biological environments using a single optical fibre. PMID:26694413

  7. Fibre Tip Sensors for Localised Temperature Sensing Based on Rare Earth-Doped Glass Coatings

    PubMed Central

    Schartner, Erik P.; Monro, Tanya M.

    2014-01-01

    We report the development of a point temperature sensor, based on monitoring upconversion emission from erbium:ytterbium-doped tellurite coatings on the tips of optical fibres. The dip coating technique allows multiple sensors to be fabricated simultaneously, while confining the temperature-sensitive region to a localised region on the end-face of the fibre. The strong response of the rare earth ions to changing temperature allows a resolution of 0.1–0.3 °C to be recorded over the biologically relevant range of temperatures from 23–39 °C. PMID:25407907

  8. Torsional moment to failure for carbon fibre polysulphone expandable rivets as compared with stainless steel screws for carbon fibre-reinforced epoxy fracture plate fixation.

    PubMed

    Sell, P J; Prakash, R; Hastings, G W

    1989-04-01

    A method of securing carbon fibre-reinforced epoxy bone plates with carbon fibre polysulphone expanding rivets was investigated. Six carbon fibre-reinforced epoxy bone plates were secured to rods with carbon fibre polysulphone rivets and six were secured with standard cortical stainless steel screws. These constructions were then subjected to pure torsional load to failure. The carbon fibre expandable rivets failed at a greater torsional moment.

  9. The role of carbon fibre as a flexor tendon substitute.

    PubMed

    Rawlins, R

    1983-06-01

    Experiments have been carried out on Rhesus monkeys to determine the effectiveness of carbon fibre as a flexor tendon substitute. Though the strength, flexibility and capacity to induce a neotendon make carbon fibre an ideal flexor tendon substitute, induction of fibrosis and accompanying increase in bulk of the implant resulted in failure.

  10. Multiwalled carbon nanotube reinforced biomimetic bundled gel fibres.

    PubMed

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

    2016-08-19

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

  11. Carbon-fibre reinforced plates for problem fractures.

    PubMed

    Pemberton, D J; McKibbin, B; Savage, R; Tayton, K; Stuart, D

    1992-01-01

    We report our experience with carbon-fibre reinforced plastic (CFRP) plates in the management of 19 problem fractures complicated by either infection, nonunion, comminution or contamination. The combination offers secure fixation without inhibition of callus formation.

  12. Fibre tip pH sensor for tumor detection during surgery

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  13. Dynamic damage in carbon-fibre composites.

    PubMed

    Bourne, N K; Parry, S; Townsend, D; Withers, P J; Soutis, C; Frias, C

    2016-07-13

    The Taylor test is used to determine damage evolution in carbon-fibre composites across a range of strain rates. The hierarchy of damage across the scales is key in determining the suite of operating mechanisms and high-speed diagnostics are used to determine states during dynamic loading. Experiments record the test response as a function of the orientation of the cylinder cut from the engineered multi-ply composite with high-speed photography and post-mortem target examination. The ensuing damage occurs during the shock compression phase but three other tensile loading modes operate during the test and these are explored. Experiment has shown that ply orientations respond to two components of release; longitudinal and radial as well as the hoop stresses generated in inelastic flow at the impact surface. The test is a discriminant not only of damage thresholds but of local failure modes and their kinetics. This article is part of the themed issue 'Multiscale modelling of the structural integrity of composite materials'. PMID:27242311

  14. Dynamic damage in carbon-fibre composites.

    PubMed

    Bourne, N K; Parry, S; Townsend, D; Withers, P J; Soutis, C; Frias, C

    2016-07-13

    The Taylor test is used to determine damage evolution in carbon-fibre composites across a range of strain rates. The hierarchy of damage across the scales is key in determining the suite of operating mechanisms and high-speed diagnostics are used to determine states during dynamic loading. Experiments record the test response as a function of the orientation of the cylinder cut from the engineered multi-ply composite with high-speed photography and post-mortem target examination. The ensuing damage occurs during the shock compression phase but three other tensile loading modes operate during the test and these are explored. Experiment has shown that ply orientations respond to two components of release; longitudinal and radial as well as the hoop stresses generated in inelastic flow at the impact surface. The test is a discriminant not only of damage thresholds but of local failure modes and their kinetics. This article is part of the themed issue 'Multiscale modelling of the structural integrity of composite materials'.

  15. Fatigue properties of unidirectional carbon fibre composites at cryogenic temperatures

    NASA Astrophysics Data System (ADS)

    Pannkoke, K.; Wagner, H.-J.

    Design engineers working with composite materials are still confronted with uncertainties as to their fatigue behaviour, especially for cryogenic applications. In the course of cooling, different thermal contraction of the fibre and matrix gives rise to thermal stresses and strains which influence most of the mechanical properties. In this paper, the fatigue behaviour of unidirectional (UD) composites with different fibres and matrices will be described. A first step in understanding the failure mechanism under cyclic loading will be presented. In earlier tests excellent fatigue properties were found for carbon fibre UD composites made of T300 carbon fibres and an epoxy matrix 1,2. However, the applied epoxy resin was brittle, especially at low temperatures. Therefore the brittle resin was substituted by polycarbonate (PC), a tough thermoplastic polymer 3,4. Nevertheless, for a composite with that matrix the fatigue endurance limit, normalized to the static strength, was found to be much lower (43%). SEM studies illustrated a poor fibre - matrix bond. To determine the bond's influence on fatigue properties, another tough matrix system was tested. The polymer PEEK is known to build a strong bond to carbon fibres, initiated by crystal growth onto the fibre surface 4,5. However, investigations on the fatigue behaviour of this composite at 77 K yielded the same low fatigue endurance limit as was found for the carbon fibre - PC system 4. At this point it can be concluded that the poor fatigue behaviour is not necessarily due to a strong or poor fibre - matrix bond. It is the purpose of this work to examine whether this different fatigue behaviour is due to matrix failure.

  16. Surface characterisation of carbon fibre recycled using fluidised bed

    NASA Astrophysics Data System (ADS)

    Jiang, G.; Pickering, S. J.; Walker, G. S.; Wong, K. H.; Rudd, C. D.

    2008-02-01

    X-ray photoelectron spectroscopy (XPS) was used to investigate the surface of carbon fibres recycled using a high-temperature fluidised bed. The interfacial shear strength of the recycled carbon fibres with epoxy resin was examined using a micro-droplet test. The corresponding as received carbon fibres were used as control samples. It was shown that the recycling process converted some of the surface hydroxyl groups into carbonyl and carboxylic groups due to the effect of heat in atmosphere of air. The overall O/C ratio was not changed significantly. The interfacial shear strength with epoxy resin was not affected by the change of surface oxygen composition. It was also shown that surface texture may play a dominant role in interfacial bonding performance.

  17. Carbon fibre composite for ventilation air methane (VAM) capture.

    PubMed

    Thiruvenkatachari, Ramesh; Su, Shi; Yu, Xin Xiang

    2009-12-30

    Coal mine methane (CMM) is not only a hazardous greenhouse gas but is also a wasted energy resource, if not utilised. This paper evaluates a novel adsorbent material developed for capturing methane from ventilation air methane (VAM) gas in underground coal mines. The adsorbent material is a honeycomb monolithic carbon fibre composite (HMCFC) consisting of multiple parallel flow-through channels and the material exhibits unique features including low pressure drop, good mechanical properties, ability to handle dust-containing gas streams, good thermal and electrical conductivity and selective adsorption of gases. During this study, a series of HMCFC adsorbents (using different types of carbon fibres) were successfully fabricated. Experimental data demonstrated the proof-of-concept of using the HMCFC adsorbent to capture methane from VAM gas. The adsorption capacity of the HMCFC adsorbent was twice that of commercial activated carbon. Methane concentration of 0.56% in the inlet VAM gas stream is reduced to about 0.011% after it passes through the novel carbon fibre composite adsorbent material at ambient temperature and atmospheric pressure. This amounts to a maximum capture efficiency of 98%. These encouraging laboratory scale studies have prompted further large scale trials and economic assessment.

  18. Carbon fibre composite for ventilation air methane (VAM) capture.

    PubMed

    Thiruvenkatachari, Ramesh; Su, Shi; Yu, Xin Xiang

    2009-12-30

    Coal mine methane (CMM) is not only a hazardous greenhouse gas but is also a wasted energy resource, if not utilised. This paper evaluates a novel adsorbent material developed for capturing methane from ventilation air methane (VAM) gas in underground coal mines. The adsorbent material is a honeycomb monolithic carbon fibre composite (HMCFC) consisting of multiple parallel flow-through channels and the material exhibits unique features including low pressure drop, good mechanical properties, ability to handle dust-containing gas streams, good thermal and electrical conductivity and selective adsorption of gases. During this study, a series of HMCFC adsorbents (using different types of carbon fibres) were successfully fabricated. Experimental data demonstrated the proof-of-concept of using the HMCFC adsorbent to capture methane from VAM gas. The adsorption capacity of the HMCFC adsorbent was twice that of commercial activated carbon. Methane concentration of 0.56% in the inlet VAM gas stream is reduced to about 0.011% after it passes through the novel carbon fibre composite adsorbent material at ambient temperature and atmospheric pressure. This amounts to a maximum capture efficiency of 98%. These encouraging laboratory scale studies have prompted further large scale trials and economic assessment. PMID:19733967

  19. Carbon fibre reinforced plastic applied to prosthetics and orthotics.

    PubMed

    Nelham, R L

    1981-10-01

    This paper describes the work carried out at the Rehabilitation Engineering Unit, Chailey Heritage Hospital, in applying carbon fibre reinforced plastic CFRP to prosthetics and orthotics. The prosthetic application relates to the construction of the Chailey Harness which was used to mount externally powered, upper limb prostheses to the torso of limb deficient children damaged by the drug Thalidomide. The application to orthotics was limited to Hip-Knee-Ankle-Orthoses (HKAO) as worn by severely handicapped children with spina bifida and led to the development of a shapable CFRP/aluminium alloy hybrid composite bar. The construction of the composite, its properties and the assembly and performance of the first orthoses are described. Some of the practical problems experienced with the use of carbon fibre reinforced plastic are identified.

  20. Charge effect in point projection images of carbon fibres

    PubMed

    Prigent; Morin

    2000-09-01

    Nanometre-sized carbon fibres across holes have been observed in a lensless point projection field-emission microscope operating between 100 and 300 eV. At sufficiently high magnification fringe patterns appear; with the help of simulations we show that they are strongly dependent on the charge density of the fibres. These patterns are characterized by an odd number of fringes with a central fringe that becomes very bright as the charge increases. Average diameter and linear charge density have been obtained with remarkable precision from analysis of fringes. Charge distribution from the middle to the edge of fibres has been investigated as well as narrowings at localized places on the fringe pattern. From these two examples, the limits of the models used for the simulations and those of the data acquisition system are discussed. Finally, this work emphasizes the fact that the fringe pattern masks the actual form of the fibre and that it is necessary to take account of the charge effect to interpret this diffraction pattern. PMID:10971800

  1. Gbit/s data transmission on carbon fibres

    NASA Astrophysics Data System (ADS)

    Flick, T.; Glitza, K.-W.; Kappen, G. C.; Mättig, P.; Möller, J.; Sanny, B.

    2016-03-01

    Data transmission at the upgraded Large Hadron Collider experiments, foreseen for mid 2020s, will be in the multi Gbit/s range per connection for the innermost detector layers. This paper reports on first tests on the possible use of carbon cables for electrical data transmission close to the interaction point. Carbon cables have the potential advantage of being light, having a low activation and easy integration into the detector components close to the interaction point. In these tests commercially available carbon fibres were used, in which the filaments had a very thin nickel coating. For these cables data rates beyond 1 Gbit/s over more than 1 m with an error rate of less than 10-12 could be reached. The characteristics of the cables have been measured in terms of S-parameters and could be converted to a SPICE model. Some outlook on potential further improvements is presented.

  2. Nanostructuring carbon fibre probes for use in central venous catheters.

    PubMed

    Li, Meixian; Phair, Jolene; Cardosi, Marco F; Davis, James

    2014-02-17

    A carbon fibre probe is described which utilises the oxidation of an endogenous biomarker to provide diagnostic information on the condition of intravascular access lines. The probe surface was modified through anodic oxidation to provide a high selectivity towards urate which was used as a redox probe through which the pH could be determined. A Nernstian response (-60 mV/pH) was obtained which was free from the interference of other redox species common to biofluids. The electroanalytical performance of the probe has been optimised and the applicability of the approach demonstrated through testing the responses in whole blood.

  3. Pulse-Width Increase of Reflex Triode Vircator Using the Carbon Fibre Cathode

    NASA Astrophysics Data System (ADS)

    Liu, Lie; Li, Li-Min; Zhang, Xiao-Ping; Wen, Jian-Chun; Wan, Hong

    2006-04-01

    We present the investigation on the reflex triode virtual cathode oscillator in which performances of carbon-fibre and stainless-steel cathodes are compared with each other. The experimental results and analyses show that surface tracking induces the electron emission of the carbon fibre cathode. There are electron emission phenomena observed not only from the top of the carbon fibre but also from its side surface. Compared with the case of the stainless steel cathode, the plasma expansion velocity for the carbon fibre cathode is slower, and using the carbon fibre cathode can widen the pulse width of output microwave. The output microwave pulse width reaches an increase of about 20%. This mechanism is different from the conventional explosive emission of metal cathodes.

  4. Development of flax/carbon fibre hybrid composites for enhanced properties.

    PubMed

    Dhakal, H N; Zhang, Z Y; Guthrie, R; Macmullen, J; Bennett, N

    2013-07-01

    Uni-directional (UD) and cross-ply (CP) cellulosic flax fibre epoxy composites were produced by hybridising UD carbon fibre prepreg onto flax system. A compression moulding technique was used to produce both flax and carbon/flax hybridised laminates. The effect of carbon fibre hybridisation on the water absorption behaviour, thermal and mechanical properties of both UD and CP flax specimens were investigated by means of water absorption, tensile, thermogravemetric analysis and flexural testing. The results showed that water absorption behaviour of hybrid samples are markedly improved compared to those without hybridisation. Similarly, the thermal stability, tensile and flexural properties of the hybrid composites are significantly improved in comparison with UD and CP flax composites without hybridisation. The experimental results suggest that cellulosic flax fibre reinforcement contributed to improve the toughness properties by promoting crack propagation whereas the carbon fibre contributed in improving thermal stability, water absorption behaviour and the overall strength and the stiffness of the hybrid composites.

  5. High heat flux erosion of carbon fibre composite materials in the TEXTOR tokamak.

    SciTech Connect

    Hassanein, A.

    1998-03-10

    During plasma disruptions, ELMs, or vertical displacement events (VDEs) high transient heat loads to the plasma facing materials an cause damage such as thermal erosion, cracking, or melting. Self shielding processes, which take place when a material surface is exposed to a high heat flux from an incident plasma, can lead to a reduction of the deposited energy. Experiments using the fast pneumatic probe of the TEXTOR tokamak were carried out to investigate these effects. The materials tested were carbon fibre reinforced materials with and without Si-addition. The probe with the material specimens was introduced into the edge plasma up to a depth of 9 cm in front of the ALT41 main limiter with a residence time of 80 ms. After the repeated exposure to the TEXTOR-plasma, the material specimens were examined by profilometry and electron microscopy to determine the damage and erosion. It was found that only a very limited zone of the probe tip of about 2.5 mm extension in radial direction showed erosion. The maximum erosion was observed at the very tip of the probe with approx. 30 {micro}m per exposure. The results of the erosion quantification are compared with the results from numerical simulations and from plasma diagnostic measurements during the exposure of the specimens.

  6. Multimode fibre: Light-sheet microscopy at the tip of a needle.

    PubMed

    Plöschner, Martin; Kollárová, Věra; Dostál, Zbyněk; Nylk, Jonathan; Barton-Owen, Thomas; Ferrier, David E K; Chmelík, Radim; Dholakia, Kishan; Čižmár, Tomáš

    2015-12-14

    Light-sheet fluorescence microscopy has emerged as a powerful platform for 3-D volumetric imaging in the life sciences. Here, we introduce an important step towards its use deep inside biological tissue. Our new technique, based on digital holography, enables delivery of the light-sheet through a multimode optical fibre--an optical element with extremely small footprint, yet permitting complex control of light transport processes within. We show that this approach supports some of the most advanced methods in light-sheet microscopy: by taking advantage of the cylindrical symmetry of the fibre, we facilitate the wavefront engineering methods for generation of both Bessel and structured Bessel beam plane illumination. Finally, we assess the quality of imaging on a sample of fluorescent beads fixed in agarose gel and we conclude with a proof-of-principle imaging of a biological sample, namely the regenerating operculum prongs of Spirobranchus lamarcki.

  7. Multimode fibre: Light-sheet microscopy at the tip of a needle

    PubMed Central

    Plöschner, Martin; Kollárová, Věra; Dostál, Zbyněk; Nylk, Jonathan; Barton-Owen, Thomas; Ferrier, David E. K.; Chmelík, Radim; Dholakia, Kishan; Čižmár, Tomáš

    2015-01-01

    Light-sheet fluorescence microscopy has emerged as a powerful platform for 3-D volumetric imaging in the life sciences. Here, we introduce an important step towards its use deep inside biological tissue. Our new technique, based on digital holography, enables delivery of the light-sheet through a multimode optical fibre – an optical element with extremely small footprint, yet permitting complex control of light transport processes within. We show that this approach supports some of the most advanced methods in light-sheet microscopy: by taking advantage of the cylindrical symmetry of the fibre, we facilitate the wavefront engineering methods for generation of both Bessel and structured Bessel beam plane illumination. Finally, we assess the quality of imaging on a sample of fluorescent beads fixed in agarose gel and we conclude with a proof-of-principle imaging of a biological sample, namely the regenerating operculum prongs of Spirobranchus lamarcki. PMID:26657400

  8. Multimode fibre: Light-sheet microscopy at the tip of a needle

    NASA Astrophysics Data System (ADS)

    Plöschner, Martin; Kollárová, Věra; Dostál, Zbyněk; Nylk, Jonathan; Barton-Owen, Thomas; Ferrier, David E. K.; Chmelík, Radim; Dholakia, Kishan; Čižmár, Tomáš

    2015-12-01

    Light-sheet fluorescence microscopy has emerged as a powerful platform for 3-D volumetric imaging in the life sciences. Here, we introduce an important step towards its use deep inside biological tissue. Our new technique, based on digital holography, enables delivery of the light-sheet through a multimode optical fibre - an optical element with extremely small footprint, yet permitting complex control of light transport processes within. We show that this approach supports some of the most advanced methods in light-sheet microscopy: by taking advantage of the cylindrical symmetry of the fibre, we facilitate the wavefront engineering methods for generation of both Bessel and structured Bessel beam plane illumination. Finally, we assess the quality of imaging on a sample of fluorescent beads fixed in agarose gel and we conclude with a proof-of-principle imaging of a biological sample, namely the regenerating operculum prongs of Spirobranchus lamarcki.

  9. Carbon fibre composite deformable mirrors: developments at UCL

    NASA Astrophysics Data System (ADS)

    Kendrew, Sarah; Doel, Peter; Brooks, David; King, Andrew M.; Dorn, Chris; Dwan, Richard M.; Yates, Chris; Dando, Glyn; Richardson, Ian; Evans, Glynn

    2006-06-01

    Adaptive optics performance is essential for achieving the demanding science goals set for the ground-based optical telescopes of the future - the so-called extremely large telescopes (ELTs). Research into novel technologies for lightweight and robust active and adaptive mirrors is crucial for ensuring this capability. Surface quality, form, and a high level of stability during operation are very important criteria for such mirrors. In 2004 we reported initial results from a project into the design and manufacture of a prototype carbon fibre reinforced polymer (CFRP) deformable mirror. This system has now been extensively characterised and tested, and results of dynamical testing and influence function measurements are discussed here. Manual grinding and polishing resulted in a residual form error of the order of 10 μm P-V and a surface roughness of approximately 5 nm rms. A good agreement was observed between the modeling data and experimental results.

  10. Carbon fibre reinforced epoxy implants for bridging large osteoperiosteal gaps.

    PubMed

    Prakash, R; Marwah, S; Goel, S C; Tuli, S M

    1988-03-01

    An experimental study was undertaken to evaluate the suitability or otherwise of carbon fibre reinforced epoxy (CFRE) implants for bridging large osteoperiosteal gaps, devoid of periosteum. Using the basic principles of composite mechanics and simple design criteria, CFRE implants were designed and developed. These implants were put in simulated osteoperiosteal gaps in the ulna of healthy mature rabbits. Ten wk postoperative results clearly demonstrated that implants made of CFRE induced callus bone formation (in the form of woven bone) which totally encapsulated the implant thereby providing reunion of the two bone segments. Further follow-up showed formation of lamellar bones and formation in the pores of the implant. Radiological and scanning electron microscopical evidence is presented.

  11. A chemically reactive spinning dope for significant improvements in wet spun carbon nanotube fibres.

    PubMed

    González-Domínguez, Jose M; Neri, Wilfrid; Maugey, Maryse; Poulin, Philippe; Ansón-Casaos, Alejandro; Martínez, M Teresa

    2013-05-11

    Single-walled carbon nanotubes can be spun in a polyvinyl alcohol stream to produce nanocomposite fibres. We use a facile ester linking between both elements to create improved fibres which exhibit outstanding enhancements in the absence of post-processing stages, providing a promising alternative based on a chemical method. PMID:23471091

  12. High-strength carbon nanotube fibre-like ribbon with high ductility and high electrical conductivity.

    PubMed

    Wang, J N; Luo, X G; Wu, T; Chen, Y

    2014-01-01

    Macroscopic fibres made up of carbon nanotubes exhibit properties far below theoretical predictions and even much lower than those for conventional carbon fibres. Here we report improvements of mechanical and electrical properties by more than one order of magnitude by pressurized rolling. Our carbon nanotubes self-assemble to a hollow macroscopic cylinder in a tube reactor operated at high temperature and then condense in water or ethanol to form a fibre, which is continually spooled in an open-air environment. This initial fibre is densified by rolling under pressure, leading to a combination of high tensile strength (3.76-5.53 GPa), high tensile ductility (8-13%) and high electrical conductivity ((1.82-2.24) × 10(4) S cm(-1)). Our study therefore demonstrates strategies for future performance maximization and the very considerable potential of carbon nanotube assemblies for high-end uses.

  13. Modelling and simulation of randomly oriented carbon fibre-reinforced composites under thermal load

    NASA Astrophysics Data System (ADS)

    Treffler, R.; Fröschl, J.; Drechsler, K.; Ladstätter, E.

    2016-03-01

    Carbon fibre-reinforced sheet moulding compounds (CF-SMC) already exhibit a complex material behaviour under uniaxial loads due to the random orientation of the fibres in the matrix resin. Mature material models for metallic materials are generally not transferable. This paper proposes an approach for modelling the fatigue behaviour of CF-SMC based on extensive static and cyclic tests using low cost secondary carbon fibres (SCF). The main focus is on describing the stiffness degradation considering the dynamic modulus of the material. Influence factors such as temperature, orientation, rate dependence and specimen thickness were additionally considered.

  14. Bond strength of fibre glass and carbon fibre posts to the root canal walls using different resin cements.

    PubMed

    Farina, Ana Paula; Cecchin, Doglas; Garcia, Lucas da Fonseca Roberti; Naves, Lucas Zago; Pires-de-Souza, Fernanda de Carvalho Panzeri

    2011-08-01

    The aim of the study was to evaluate the bond strength of fibre glass and carbon fibre posts in the root canal walls cemented with self-adhesive (RelyX-Unicem) and chemical (Cement-Post) resin cements. Forty maxillary canines were divided into four groups according to the cement and post used and submitted to the push-out test (0.5 mm min(-1)). The data were submitted to statistical analysis (2-way ANOVA, Bonferroni--P<0.05) and fracture analysis by Scanning Electronic Microscopy. Fibre glass presented the best results when cemented with RelyX-Unicem and Cement-Post (P<0.05). RelyX-Unicem presented the highest bond strength values for both posts (P<0.05). Fracture analysis showed predominance of cohesive fracture of post for RelyX-Unicem and adhesive fracture between dentin/cement and mixed for Cement-Post. The bond strength values were significantly affected by the type of post and cement used and the highest values were found for fibre glass posts and RelyX-Unicem.

  15. Recycling of woven carbon-fibre-reinforced polymer composites using supercritical water.

    PubMed

    Knight, Chase C; Zeng, Changchun; Zhang, Chuck; Wang, Ben

    2012-01-01

    Over the past few years, there has been great deal of interest in recycling carbon-fibre-reinforced polymer composites. One method that has shown promising results involves the use of supercritical fluids to achieve separation between matrix and fibres by effectively degrading the resin into lower molecular weight compounds. In addition, the solvents used are environmentally benign and can also be recovered and reused. In this study, supercritical water with 0.05 M KOH as the catalyst was used for the recycling of an aerospace-grade high-performance epoxy carbon fibre composite (Hexcel 8552/IM7). The morphology of the reclaimed fibres was observed by scanning electron microscopy, and the tensile properties of the fibres were measured by single filament testing. The effects of processing time on the resin elimination efficiency and fibre property retention were investigated. With the process developed in this research, as much as 99.2 wt% resin elimination was achieved, resulting in the recovery of clean, undamaged fibres. The reclaimed fibres retained the original tensile strength. The feasibility of recycling multiple layer composites was also explored.

  16. N-type thermoelectric recycled carbon fibre sheet with electrochemically deposited Bi2Te3

    NASA Astrophysics Data System (ADS)

    Pang, E. J. X.; Pickering, S. J.; Chan, A.; Wong, K. H.

    2012-06-01

    An N-type thermoelectric recycled carbon fibre sheet with bismuth telluride coating has been successfully synthesised through an electrodeposition technique. The Seebeck coefficient and electrical properties of the combined recycled carbon fibre sheet and bismuth telluride films are reported. Classification of the crystal structure, surface morphology and the elemental composition of the resulting deposits are methodically characterised by XRD, SEM and EDX correspondingly. Cyclic voltammetry is also carried out in nitric acid solutions to investigate the right range of deposition potential. An N-type thermoelectric sheet was successfully synthesised with the highest attainable Seebeck coefficient of -54 μV/k with an electrical resistivity of 8.9 × 10-5 ohm m. The results shows slight differences in morphologies and thermoelectric properties for the films deposited at varying deposition potential. The increase in thermoelectrical properties of the recycled carbon fibre is in line with the development of using coated recycled fibre for thermoelectrical applications.

  17. N-type thermoelectric recycled carbon fibre sheet with electrochemically deposited Bi2Te3

    NASA Astrophysics Data System (ADS)

    Pang, E. J. X.; Pickering, S. J.; Chan, A.; Wong, K. H.; Lau, P. L.

    2012-09-01

    An N-type thermoelectric recycled carbon fibre sheet with bismuth telluride coating has been successfully synthesised through an electro-deposition technique. The Seebeck coefficient and electrical properties of the combined recycled carbon fibre sheet and bismuth telluride films are reported. Classification of the crystal structure, surface morphology and the elemental composition of the resulting deposits are methodically characterised by XRD, SEM and EDX. Cyclic voltammetry is also carried out in nitric acid solutions to investigate the right range of deposition potential. The synthesis N-type thermoelectric sheet has a highest attainable Seebeck coefficient of -54 μV K-1 and an electrical resistivity of 8.9×10-5 Ω m. The results show slight differences in morphologies and thermoelectric properties for the films deposited at varying deposition potential. The increase in thermoelectrical properties of the recycled carbon fibre is in line with the development of using coated recycled fibre for thermoelectrical applications.

  18. Self-tapping ability of carbon fibre reinforced polyetheretherketone suture anchors.

    PubMed

    Feerick, Emer M; Wilson, Joanne; Jarman-Smith, Marcus; Ó'Brádaigh, Conchur M; McGarry, J Patrick

    2014-10-01

    An experimental and computational investigation of the self-tapping ability of carbon fibre reinforced polyetheretherketone (CFR-PEEK) has been conducted. Six CFR-PEEK suture anchor designs were investigated using PEEK-OPTIMA® Reinforced, a medical grade of CFR-PEEK. Experimental tests were conducted to investigate the maximum axial force and torque required for self-taping insertion of each anchor design. Additional experimental tests were conducted for some anchor designs using pilot holes. Computational simulations were conducted to determine the maximum stress in each anchor design at various stages of insertion. Simulations also were performed to investigate the effect of wall thickness in the anchor head. The maximum axial force required to insert a self-tapping CFR-PEEK suture anchor did not exceed 150 N for any anchor design. The maximum torque required to insert a self-tapping CFR-PEEK suture anchor did not exceed 0.8 Nm. Computational simulations reveal significant stress concentrations in the region of the anchor tip, demonstrating that a re-design of the tip geometry should be performed to avoid fracture during self-tapping, as observed in the experimental component of this study. This study demonstrates the ability of PEEK-OPTIMA Reinforced suture anchors to self-tap polyurethane foam bone analogue. This provides motivation to further investigate the self-tapping ability of CFR-PEEK suture anchors in animal/cadaveric bone. An optimised design for CFR-PEEK suture anchors offers the advantages of radiolucency, and mechanical properties similar to bone with the ability to self-tap. This may have positive implications for reducing surgery times and the associated costs with the procedure.

  19. Radiation processing of carbon fibre-reinforced advanced composites

    NASA Astrophysics Data System (ADS)

    Singh, Ajit

    2001-12-01

    Carbon fibre-reinforced advanced composites are being used for a variety of structural applications, because of their useful mechanical properties, including high strength-to-weight ratio and corrosion resistance. Thermal curing of composite products results in internal stresses, due to the mismatch of the coefficients of expansion of the tools and the composite products. Because radiation curing can be done at ambient temperatures, the possibility that the residual stresses might be absent, or much lower in the radiation-cured products, originally led to the start of work on radiation curing of advanced composites at AECL's Whiteshell Laboratories in Pinawa, Canada, in 1985. Research work during the last two decades has shown that advanced composites can be radiation-cured with electron beams or γ radiation. Many of the advantages of radiation curing, as compared to thermal curing, which include curing at ambient temperature, reduced curing time, improved resin stability and reduced volatile emissions, have now been demonstrated. The initial work focussed on electron curing of acrylated epoxy matrices. Since then, procedures have been developed to radiation cure conventional aerospace epoxies, as well. Electron beam cured advanced composites are now being developed for use in the aircraft and aerospace industry. Repair of advanced composite structures is also possible using radiation curing technology. Radiation curing work is continuing at Pinawa and has also been done by Aerospatiale, who have facilities for electron curing composite rocket motor casings and by Chappas and co-workers who have electron cured part of a boat hull. In this paper, the work done on this emerging new technology by the various groups is briefly reviewed.

  20. High Power Q-Switched Thulium Doped Fibre Laser using Carbon Nanotube Polymer Composite Saturable Absorber.

    PubMed

    Chernysheva, Maria; Mou, Chengbo; Arif, Raz; AlAraimi, Mohammed; Rümmeli, Mark; Turitsyn, Sergei; Rozhin, Aleksey

    2016-01-01

    We have proposed and demonstrated a Q-switched Thulium doped fibre laser (TDFL) with a 'Yin-Yang' all-fibre cavity scheme based on a combination of nonlinear optical loop mirror (NOLM) and nonlinear amplified loop mirror (NALM). Unidirectional lasing operation has been achieved without any intracavity isolator. By using a carbon nanotube polymer composite based saturable absorber (SA), we demonstrated the laser output power of ~197 mW and pulse energy of 1.7 μJ. To the best of our knowledge, this is the highest output power from a nanotube polymer composite SA based Q-switched Thulium doped fibre laser. PMID:27063511

  1. High Power Q-Switched Thulium Doped Fibre Laser using Carbon Nanotube Polymer Composite Saturable Absorber

    PubMed Central

    Chernysheva, Maria; Mou, Chengbo; Arif, Raz; AlAraimi, Mohammed; Rümmeli, Mark; Turitsyn, Sergei; Rozhin, Aleksey

    2016-01-01

    We have proposed and demonstrated a Q-switched Thulium doped fibre laser (TDFL) with a ‘Yin-Yang’ all-fibre cavity scheme based on a combination of nonlinear optical loop mirror (NOLM) and nonlinear amplified loop mirror (NALM). Unidirectional lasing operation has been achieved without any intracavity isolator. By using a carbon nanotube polymer composite based saturable absorber (SA), we demonstrated the laser output power of ~197 mW and pulse energy of 1.7 μJ. To the best of our knowledge, this is the highest output power from a nanotube polymer composite SA based Q-switched Thulium doped fibre laser. PMID:27063511

  2. High Power Q-Switched Thulium Doped Fibre Laser using Carbon Nanotube Polymer Composite Saturable Absorber.

    PubMed

    Chernysheva, Maria; Mou, Chengbo; Arif, Raz; AlAraimi, Mohammed; Rümmeli, Mark; Turitsyn, Sergei; Rozhin, Aleksey

    2016-01-01

    We have proposed and demonstrated a Q-switched Thulium doped fibre laser (TDFL) with a 'Yin-Yang' all-fibre cavity scheme based on a combination of nonlinear optical loop mirror (NOLM) and nonlinear amplified loop mirror (NALM). Unidirectional lasing operation has been achieved without any intracavity isolator. By using a carbon nanotube polymer composite based saturable absorber (SA), we demonstrated the laser output power of ~197 mW and pulse energy of 1.7 μJ. To the best of our knowledge, this is the highest output power from a nanotube polymer composite SA based Q-switched Thulium doped fibre laser.

  3. High Power Q-Switched Thulium Doped Fibre Laser using Carbon Nanotube Polymer Composite Saturable Absorber

    NASA Astrophysics Data System (ADS)

    Chernysheva, Maria; Mou, Chengbo; Arif, Raz; Alaraimi, Mohammed; Rümmeli, Mark; Turitsyn, Sergei; Rozhin, Aleksey

    2016-04-01

    We have proposed and demonstrated a Q-switched Thulium doped fibre laser (TDFL) with a ‘Yin-Yang’ all-fibre cavity scheme based on a combination of nonlinear optical loop mirror (NOLM) and nonlinear amplified loop mirror (NALM). Unidirectional lasing operation has been achieved without any intracavity isolator. By using a carbon nanotube polymer composite based saturable absorber (SA), we demonstrated the laser output power of ~197 mW and pulse energy of 1.7 μJ. To the best of our knowledge, this is the highest output power from a nanotube polymer composite SA based Q-switched Thulium doped fibre laser.

  4. Low Cost Carbon Fibre: Applications, Performance and Cost Models - Chapter 17

    SciTech Connect

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

    2014-01-01

    Weight saving in automotive applications has a major bearing on fuel economy. It is generally accepted that, typically, a 10% weight reduction in an automobile will lead to a 6-8% improvement in fuel economy. In this respect, carbon fibre composites are extremely attractive in their ability to provide superlative mechanical performance per unit weight. That is why they are specified for high-end uses such as Formula 1 racing cars and the latest aircraft (e.g. Boeing 787, Airbus A350 and A380), where they comprise over 50% by weight of the structure However, carbon fibres are expensive and this renders their composites similarly expensive. Research has been carried out at Oak Ridge National Laboratories (ORNL), Tennessee, USA for over a decade with the aim of reducing the cost of carbon fibre such that it becomes a cost-effective option for the automotive industry. Aspects of this research relating to the development of low cost carbon fibre have been reported in Chapter 3 of this publication. In this chapter, the practical industrial applications of low-cost carbon fibre are presented, together with considerations of the performance and cost models which underpin the work.

  5. Biological and physicochemical properties of carbon-graphite fibre-reinforced polymers intended for implant suprastructures.

    PubMed

    Segerström, Susanna; Sandborgh-Englund, Gunilla; Ruyter, Eystein I

    2011-06-01

    The aim of this study was to determine water sorption, water solubility, dimensional change caused by water storage, residual monomers, and possible cytotoxic effects of heat-polymerized carbon-graphite fibre-reinforced composites with different fibre loadings based on methyl methacrylate/poly(methyl methacrylate) (MMA/PMMA) and the copolymer poly (vinyl chloride-co-vinyl acetate). Two different resin systems were used. Resin A contained ethylene glycol dimethacrylate (EGDMA) and 1,4-butanediol dimethacrylate (1,4-BDMA); the cross-linker in Resin B was diethylene glycol dimethacrylate (DEGDMA). The resin mixtures were reinforced with 24, 36 and 47 wt% surface-treated carbon-graphite fibres. In addition, polymer B was reinforced with 58 wt% fibres. Water sorption was equal to or below 3.34±1.18 wt%, except for the 58 wt% fibre loading of polymer B (5.27±1.22 wt%). Water solubility was below 0.36±0.015 wt%, except for polymer B with 47 and 58 wt% fibres. For all composites, the volumetric increase was below 0.01±0.005 vol%. Residual MMA monomer was equal to or below 0.68±0.05 wt% for the fibre composites. The filter diffusion test and the (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) (MTT) assay demonstrated no cytotoxicity for the carbon-graphite fibre-reinforced composites, and residual cross-linking agents and vinyl chloride were not detectable by high-performance liquid chromatography (HPLC) analysis.

  6. FTIR study of degradation products of aliphatic polyesters carbon fibres composites

    NASA Astrophysics Data System (ADS)

    Pamuła, Elżbieta; Błażewicz, Marta; Paluszkiewicz, Czesława; Dobrzyński, Piotr

    2001-09-01

    Biodegradable polymer composites based on polylactides and polyglycolides constitute a group of materials characterised by good biocompatibility. They are considered in tissue engineering as scaffolds for cells proliferation and controlled tissue regeneration. Two types of biodegradable polymers possessing different chemical structure, molecular weights and crystallinity degrees and two composite materials made up of them and carbon fibres were analysed in this study. The samples were incubated in aqueous media for 8 weeks and analysed by means of Fourier transform infrared spectroscopy in the attenuated total reflection mode (FTIR-ATR). Infrared spectroscopy enabled identification of degradation products and estimation of the influence of carbon fibres on hydrolytic degradation of analysed polymers. Analysis of the infrared spectra showed that hydrolytic degradation process depends on chemical structure, molecular weight and crystallinity of polymers. Catalytic effect of carbon fibres at the initial stage of polymer degradation was observed. Further degradation is dependent on the properties of polymer.

  7. The oxidative stability of carbon fibre reinforced glass-matrix composites

    NASA Technical Reports Server (NTRS)

    Prewo, K. M.; Batt, J. A.

    1988-01-01

    The environmental stability of carbon fibre reinforced glass-matrix composites is assessed. Loss of composite strength due to oxidative exposure at elevated temperatures under no load, static load and cyclic fatigue as well as due to thermal cycling are all examined. It is determined that strength loss is gradual and predictable based on the oxidation of carbon fibres. The glass matrix was not found to prevent this degradation but simply to limit it to a gradual process progressing from the composite surfaces inward.

  8. A Spray Pyrolysis Method to Grow Carbon Nanotubes on Carbon Fibres, Steel and Ceramic Bricks.

    PubMed

    Vilatela, Juan J; Rabanal, M E; Cervantes-Sodi, Felipe; García-Ruiz, Máximo; Jiménez-Rodríguez, José A; Reiband, Gerd; Terrones, Mauricio

    2015-04-01

    We demonstrate a spray pyrolysis method to grow carbon nanotubes (CNTs) with high degree of crystallinity, aspect ratio and degree of alignment on a variety of different substrates, such as conventional steel, carbon fibres (CF) and ceramics. The process consists in the chemical vapour deposition of both a thin SiO2 layer and CNTs that subsequently grow on this thin layer. After CNT growth, increases in specific surface by factors of 1000 and 30 for the steel and CF samples, respectively, are observed. CNTs growth on ceramic surfaces results in a surface resistance of 37.5 Ohm/sq. When using conventional steel as a rector tube, we observed CNTs growth rates of 0.6 g/min. Details of nanotube morphology and the growth mechanism are discussed. Since the method discussed here is highly versatile, it opens up a wide variety of applications in which specific substrates could be used in combination with CNTs.

  9. Catalyst-induced growth of carbon nanotubes on tips of cantilevers and nanowires

    DOEpatents

    Lee, James Weifu; Lowndes, Douglas H.; Merkulov, Vladimir I.; Eres, Gyula; Wei, Yayi; Greenbaum, Elias; Lee, Ida

    2004-06-29

    A method is described for catalyst-induced growth of carbon nanotubes, nanofibers, and other nanostructures on the tips of nanowires, cantilevers, conductive micro/nanometer structures, wafers and the like. The method can be used for production of carbon nanotube-anchored cantilevers that can significantly improve the performance of scaning probe microscopy (AFM, EFM etc). The invention can also be used in many other processes of micro and/or nanofabrication with carbon nanotubes/fibers. Key elements of this invention include: (1) Proper selection of a metal catalyst and programmable pulsed electrolytic deposition of the desired specific catalyst precisely at the tip of a substrate, (2) Catalyst-induced growth of carbon nanotubes/fibers at the catalyst-deposited tips, (3) Control of carbon nanotube/fiber growth pattern by manipulation of tip shape and growth conditions, and (4) Automation for mass production.

  10. Synergistic toughening of composite fibres by self-alignment of reduced graphene oxide and carbon nanotubes.

    PubMed

    Shin, Min Kyoon; Lee, Bommy; Kim, Shi Hyeong; Lee, Jae Ah; Spinks, Geoffrey M; Gambhir, Sanjeev; Wallace, Gordon G; Kozlov, Mikhail E; Baughman, Ray H; Kim, Seon Jeong

    2012-01-01

    The extraordinary properties of graphene and carbon nanotubes motivate the development of methods for their use in producing continuous, strong, tough fibres. Previous work has shown that the toughness of the carbon nanotube-reinforced polymer fibres exceeds that of previously known materials. Here we show that further increased toughness results from combining carbon nanotubes and reduced graphene oxide flakes in solution-spun polymer fibres. The gravimetric toughness approaches 1,000 J g(-1), far exceeding spider dragline silk (165 J g(-1)) and Kevlar (78 J g(-1)). This toughness enhancement is consistent with the observed formation of an interconnected network of partially aligned reduced graphene oxide flakes and carbon nanotubes during solution spinning, which act to deflect cracks and allow energy-consuming polymer deformation. Toughness is sensitive to the volume ratio of the reduced graphene oxide flakes to the carbon nanotubes in the spinning solution and the degree of graphene oxidation. The hybrid fibres were sewable and weavable, and could be shaped into high-modulus helical springs. PMID:22337128

  11. Synergistic toughening of composite fibres by self-alignment of reduced graphene oxide and carbon nanotubes

    PubMed Central

    Shin, Min Kyoon; Lee, Bommy; Kim, Shi Hyeong; Lee, Jae Ah; Spinks, Geoffrey M.; Gambhir, Sanjeev; Wallace, Gordon G.; Kozlov, Mikhail E.; Baughman, Ray H.; Kim, Seon Jeong

    2012-01-01

    The extraordinary properties of graphene and carbon nanotubes motivate the development of methods for their use in producing continuous, strong, tough fibres. Previous work has shown that the toughness of the carbon nanotube-reinforced polymer fibres exceeds that of previously known materials. Here we show that further increased toughness results from combining carbon nanotubes and reduced graphene oxide flakes in solution-spun polymer fibres. The gravimetric toughness approaches 1,000 J g−1, far exceeding spider dragline silk (165 J g−1) and Kevlar (78 J g−1). This toughness enhancement is consistent with the observed formation of an interconnected network of partially aligned reduced graphene oxide flakes and carbon nanotubes during solution spinning, which act to deflect cracks and allow energy-consuming polymer deformation. Toughness is sensitive to the volume ratio of the reduced graphene oxide flakes to the carbon nanotubes in the spinning solution and the degree of graphene oxidation. The hybrid fibres were sewable and weavable, and could be shaped into high-modulus helical springs. PMID:22337128

  12. Synergistic toughening of composite fibres by self-alignment of reduced graphene oxide and carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Shin, Min Kyoon; Lee, Bommy; Kim, Shi Hyeong; Lee, Jae Ah; Spinks, Geoffrey M.; Gambhir, Sanjeev; Wallace, Gordon G.; Kozlov, Mikhail E.; Baughman, Ray H.; Kim, Seon Jeong

    2012-01-01

    The extraordinary properties of graphene and carbon nanotubes motivate the development of methods for their use in producing continuous, strong, tough fibres. Previous work has shown that the toughness of the carbon nanotube-reinforced polymer fibres exceeds that of previously known materials. Here we show that further increased toughness results from combining carbon nanotubes and reduced graphene oxide flakes in solution-spun polymer fibres. The gravimetric toughness approaches 1,000 J g-1, far exceeding spider dragline silk (165 J g-1) and Kevlar (78 J g-1). This toughness enhancement is consistent with the observed formation of an interconnected network of partially aligned reduced graphene oxide flakes and carbon nanotubes during solution spinning, which act to deflect cracks and allow energy-consuming polymer deformation. Toughness is sensitive to the volume ratio of the reduced graphene oxide flakes to the carbon nanotubes in the spinning solution and the degree of graphene oxidation. The hybrid fibres were sewable and weavable, and could be shaped into high-modulus helical springs.

  13. Synergistic toughening of composite fibres by self-alignment of reduced graphene oxide and carbon nanotubes.

    PubMed

    Shin, Min Kyoon; Lee, Bommy; Kim, Shi Hyeong; Lee, Jae Ah; Spinks, Geoffrey M; Gambhir, Sanjeev; Wallace, Gordon G; Kozlov, Mikhail E; Baughman, Ray H; Kim, Seon Jeong

    2012-01-31

    The extraordinary properties of graphene and carbon nanotubes motivate the development of methods for their use in producing continuous, strong, tough fibres. Previous work has shown that the toughness of the carbon nanotube-reinforced polymer fibres exceeds that of previously known materials. Here we show that further increased toughness results from combining carbon nanotubes and reduced graphene oxide flakes in solution-spun polymer fibres. The gravimetric toughness approaches 1,000 J g(-1), far exceeding spider dragline silk (165 J g(-1)) and Kevlar (78 J g(-1)). This toughness enhancement is consistent with the observed formation of an interconnected network of partially aligned reduced graphene oxide flakes and carbon nanotubes during solution spinning, which act to deflect cracks and allow energy-consuming polymer deformation. Toughness is sensitive to the volume ratio of the reduced graphene oxide flakes to the carbon nanotubes in the spinning solution and the degree of graphene oxidation. The hybrid fibres were sewable and weavable, and could be shaped into high-modulus helical springs.

  14. The electro-structural behaviour of yarn-like carbon nanotube fibres immersed in organic liquids

    NASA Astrophysics Data System (ADS)

    Terrones, Jeronimo; Windle, Alan H.; Elliott, James A.

    2014-10-01

    Yarn-like carbon nanotube (CNT) fibres are a hierarchically-structured material with a variety of promising applications such as high performance composites, sensors and actuators, smart textiles, and energy storage and transmission. However, in order to fully realize these possibilities, a more detailed understanding of their interactions with the environment is required. In this work, we describe a simplified representation of the hierarchical structure of the fibres from which several mathematical models are constructed to explain electro-structural interactions of fibres with organic liquids. A balance between the elastic and surface energies of the CNT bundle network in different media allows the determination of the maximum lengths that open junctions can sustain before collapsing to minimize the surface energy. This characteristic length correlates well with the increase of fibre resistance upon immersion in organic liquids. We also study the effect of charge accumulation in open interbundle junctions and derive expressions to describe experimental data on the non-ohmic electrical behaviour of fibres immersed in polar liquids. Our analyses suggest that the non-ohmic behaviour is caused by progressively shorter junctions collapsing as the voltage is increased. Since our models are not based on any property unique to carbon nanotubes, they should also be useful to describe other hierarchical structures.

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

    PubMed

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

    2016-07-13

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

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

    PubMed

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

    2016-07-13

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

  17. Theoretical study of carbon-based tips for scanning tunnelling microscopy

    NASA Astrophysics Data System (ADS)

    González, C.; Abad, E.; Dappe, Y. J.; Cuevas, J. C.

    2016-03-01

    Motivated by recent experiments, we present here a detailed theoretical analysis of the use of carbon-based conductive tips in scanning tunnelling microscopy. In particular, we employ ab initio methods based on density functional theory to explore a graphitic, an amorphous carbon and two diamond-like tips for imaging with a scanning tunnelling microscope (STM), and we compare them with standard metallic tips made of gold and tungsten. We investigate the performance of these tips in terms of the corrugation of the STM images acquired when scanning a single graphene sheet. Moreover, we analyse the impact of the tip-sample distance and show that it plays a fundamental role in the resolution and symmetry of the STM images. We also explore in depth how the adsorption of single atoms and molecules in the tip apexes modifies the STM images and demonstrate that, in general, it leads to an improved image resolution. The ensemble of our results provides strong evidence that carbon-based tips can significantly improve the resolution of STM images, as compared to more standard metallic tips, which may open a new line of research in scanning tunnelling microscopy.

  18. Theoretical study of carbon-based tips for scanning tunnelling microscopy.

    PubMed

    González, C; Abad, E; Dappe, Y J; Cuevas, J C

    2016-03-11

    Motivated by recent experiments, we present here a detailed theoretical analysis of the use of carbon-based conductive tips in scanning tunnelling microscopy. In particular, we employ ab initio methods based on density functional theory to explore a graphitic, an amorphous carbon and two diamond-like tips for imaging with a scanning tunnelling microscope (STM), and we compare them with standard metallic tips made of gold and tungsten. We investigate the performance of these tips in terms of the corrugation of the STM images acquired when scanning a single graphene sheet. Moreover, we analyse the impact of the tip-sample distance and show that it plays a fundamental role in the resolution and symmetry of the STM images. We also explore in depth how the adsorption of single atoms and molecules in the tip apexes modifies the STM images and demonstrate that, in general, it leads to an improved image resolution. The ensemble of our results provides strong evidence that carbon-based tips can significantly improve the resolution of STM images, as compared to more standard metallic tips, which may open a new line of research in scanning tunnelling microscopy. PMID:26861537

  19. Theoretical study of carbon-based tips for scanning tunnelling microscopy.

    PubMed

    González, C; Abad, E; Dappe, Y J; Cuevas, J C

    2016-03-11

    Motivated by recent experiments, we present here a detailed theoretical analysis of the use of carbon-based conductive tips in scanning tunnelling microscopy. In particular, we employ ab initio methods based on density functional theory to explore a graphitic, an amorphous carbon and two diamond-like tips for imaging with a scanning tunnelling microscope (STM), and we compare them with standard metallic tips made of gold and tungsten. We investigate the performance of these tips in terms of the corrugation of the STM images acquired when scanning a single graphene sheet. Moreover, we analyse the impact of the tip-sample distance and show that it plays a fundamental role in the resolution and symmetry of the STM images. We also explore in depth how the adsorption of single atoms and molecules in the tip apexes modifies the STM images and demonstrate that, in general, it leads to an improved image resolution. The ensemble of our results provides strong evidence that carbon-based tips can significantly improve the resolution of STM images, as compared to more standard metallic tips, which may open a new line of research in scanning tunnelling microscopy.

  20. Efficient fabrication of carbon nanotube micro tip arrays by tailoring cross-stacked carbon nanotube sheets.

    PubMed

    Wei, Yang; Liu, Peng; Zhu, Feng; Jiang, Kaili; Li, Qunqing; Fan, Shoushan

    2012-04-11

    Carbon nanotube (CNT) micro tip arrays with hairpin structures on patterned silicon wafers were efficiently fabricated by tailoring the cross-stacked CNT sheet with laser. A blade-like structure was formed at the laser-cut edges of the CNT sheet. CNT field emitters, pulled out from the end of the hairpin by an adhesive tape, can provide 150 μA intrinsic emission currents with low beam noise. The nice field emission is ascribed to the Joule-heating-induced desorption of the emitter surface by the hairpin structure, the high temperature annealing effect, and the surface morphology. The CNT emitters with hairpin structures will greatly promote the applications of CNTs in vacuum electronic devices and hold the promises to be used as the hot tips for thermochemical nanolithography. More CNT-based structures and devices can be fabricated on a large scale by this versatile method. PMID:22433000

  1. Carbon-fiber tips for scanning probe microscopes and molecular electronics experiments.

    PubMed

    Rubio-Bollinger, Gabino; Castellanos-Gomez, Andres; Bilan, Stefan; Zotti, Linda A; Arroyo, Carlos R; Agraït, Nicolás; Cuevas, Juan Carlos

    2012-01-01

    We fabricate and characterize carbon-fiber tips for their use in combined scanning tunneling and force microscopy based on piezoelectric quartz tuning fork force sensors. An electrochemical fabrication procedure to etch the tips is used to yield reproducible sub-100-nm apex. We also study electron transport through single-molecule junctions formed by a single octanethiol molecule bonded by the thiol anchoring group to a gold electrode and linked to a carbon tip by the methyl group. We observe the presence of conductance plateaus during the stretching of the molecular bridge, which is the signature of the formation of a molecular junction.

  2. Detection of bioavailable heavy metals in EILATox-Oregon samples using whole-cell luminescent bacterial sensors in suspension or immobilized onto fibre-optic tips.

    PubMed

    Hakkila, Kaisa; Green, Tal; Leskinen, Piia; Ivask, Angela; Marks, Robert; Virta, Marko

    2004-01-01

    At the EILATox-Oregon Workshop, nine luminescent whole-cell bacterial sensors were used for the determination of bioavailable metals in blind samples (17 synthetic and 3 environmental). A non-inducible luminescent control strain was used to determine sample matrix effects and bacterial toxicity. Whole-cell bacterial sensors capable of determining arsenic, inorganic mercury and its organic derivatives, cadmium, lead or copper were used in suspensions and a bacterial sensor for the detection of inorganic mercury was immobilized onto fibre-optic tips using calcium alginate. Bioavailable amounts of metals were estimated using calibration plots, that were constructed to determine the range of metals giving rise to a linear relationship between luminescence and the amount of metals present in the standard solutions. EILATox-Oregon sample 5, which contained 74 mg l(-1) of Hg, gave a significant response with both formats of the mercury sensor. The bioavailable amounts of mercury according to the measurement of bacterial sensor in suspension and immobilized onto a fibre-optic tip were 76 and 93 mg l(-1), respectively. The bacterial sensor for arsenic and copper showed a response with sample 6 (58 mg l(-1) of As) and sample 8 (400 mg l(-1) of metham sodium), respectively. This study showed that the bacterial sensors in suspension or immobilized onto optical fibres are capable of quantifying bioavailable metals from unknown samples. The measurement protocol of bacterial sensors is simple and possible to perform in the field. Moreover, the samples do not need any pretreatment before analysis. Construction and characterization of the strain for the detection of bioavailable copper are described.

  3. Fluoro-edenite and carbon nanotubes: The health impact of ‘asbestos-like’ fibres

    PubMed Central

    MIOZZI, EDOARDO; RAPISARDA, VENERANDO; MARCONI, ANDREA; COSTA, CHIARA; POLITO, IRENE; SPANDIDOS, DEMETRIOS A.; LIBRA, MASSIMO; FENGA, CONCETTINA

    2016-01-01

    Several decades have passed since Wagner et al demonstrated a causal link between asbestos fibre inhalation and the development of pleural mesothelioma in 1960. It was later suggested that pleural plaques are a benign consequence of exposure to these fibres. Most recently, a significant association between exposure to asbestos and cancer diagnosed at various sites, such as the peritoneum, stomach, pharynx, colon and ovaries has been demonstrated. The great concerns about public health that arose from the scientific evidence presented above have led to the banning of asbestos in several countries. Over the years, the suspicion that particles with a high aspect ratio may have asbestos-like pathogenicity has been supported by increasing evidence. Natural occurring minerals, as well as man-made fibres, have proven capable of inducing either chronic inflammation of serous membranes, or, in some cases, the development of peritoneal and pleural mesothelioma. The pathogenic role of both fluoro-edenite and carbon nanotubes, two ‘asbestos-like’ fibres is summarized and discussed in this review. The data presented herein support the notion that occupational exposure to these two types of fibre contributes to the development of different types of cancer. PMID:26889212

  4. Ultrasound detection of damage in complex carbon fibre/metal structures

    NASA Astrophysics Data System (ADS)

    Thursby, G. J.; MacLean, A.; Hogg, H.; Culshaw, B.

    2006-03-01

    We describe work carried out to monitor the structural health of a complex structure comprising both carbon fibre and metal components using ultrasound techniques. The work is designed to be used in a high performance car, but could find applications in other areas such as the aerospace industry. There are two different types of potential problem that need to be examined; the first is damage (e.g. holes, delaminations) to carbon fibre structure, and the second is damage to joints either between two carbon fibre components or between a carbon fibre component and a metallic one. The techniques used are based around the use of PZT transducers for both the generation and detection of ultrasonic Lamb waves. To date we have been carrying out experiments on mock-up samples, but are due to conduct tests on an actual vehicle. Lamb waves propagate in modes whose order is determined by the frequency thickness product. Their properties, such as phase and amplitude can be modified by the presence of damage, such as holes and delaminations. If we record the response of a healthy structure, we can then compare it with signals obtained on subsequent occasions to determine if any significant change has taken place. It is essential, however, to be able to differentiate between the effects of damage and those of environmental changes such as temperature. For this reason we have monitored the response of a sample at different temperatures both before and after drilling a hole in it to simulate damage. Depending on the positions of the transducers with respect to the damaged area, it is possible to detect either attenuation of the entire signal or changes in a specific portion of the signal produced by reflections. Results from these experiments will be presented at the conference. Signal processing techniques for separating damage from the effects of temperature will also be discussed. We also look at the deterioration of joints, which can either be epoxy bonded (carbon fibre to

  5. Accuracy improvement of protrusion angle of carbon nanotube tips by precision multiaxis nanomanipulator

    SciTech Connect

    Young Song, Won; Young Jung, Ki; O, Beom-Hoan; Park, Byong Chon

    2005-02-01

    In order to manufacture a carbon nanotube (CNT) tip in which the attachment angle and position of CNT were precisely adjusted, a nanomanipulator was installed inside a scanning electron microscope (SEM). A CNT tip, atomic force microscopy (AFM) probe to which a nanotube is attached, is known to be the most appropriate probe for measuring the shape of high aspect ratio. The developed nanomanipulator has two sets of modules with the degree of freedom of three-directional rectilinear motion and one-directional rotational motion at an accuracy of tens of nanometers, so it enables the manufacturing of more accurate CNT tips. The present study developed a CNT tip with the error of attachment angle less then 10 deg. through three-dimensional operation of a multiwalled carbon nanotube and an AFM probe inside a SEM.

  6. Nanoscale Etching and Indentation of Silicon(001) Surface with Carbon Nanotube Tips

    NASA Technical Reports Server (NTRS)

    Dzegilenko, Fendor N.; Srivastava, Deepak; Saini, Subhash

    1998-01-01

    The possibility of nanoscale etching and indentation of Si(001)(2x1) surface by (8,0) and (10,10) carbon nanotube tips is demonstrated, for the first time, by classical molecular dynamics simulations employing Tersoff's many-body potential for a mixed C/Si/Ge system. In the nanotube tip barely touching the surface scenario atomistic etching is observed, where as in the nanoindentation scenario nanotube tip penetrates the surface without much hindrance. The results are explained in terms of the relative strength of C-C, C-Si, and Si-Si bonds.

  7. Ultra-pure single wall carbon nanotube fibres continuously spun without promoter.

    PubMed

    Paukner, Catharina; Koziol, Krzysztof K K

    2014-01-01

    We report a new strategy towards the control of carbon nanotube (CNT) structure and continuous fibre formation using a floating catalyst direct spinning CVD process. In the procedures used to date, a sulphur promoter precursor is added to significantly enhance the rate of CNT formation in the floating catalyst synthesis. Within the reaction zone, the rapidly grown nanotubes self-assemble into bundles, followed by their continuous spinning into fibres, yarns, films or tapes. In this paper we demonstrate a catalyst control strategy in the floating catalyst system, where the CNT formation process is independent of the presence of a promoter but leads to successful spinning of the macroscopic carbon nanotube assemblies with specific morphology, high purity (Raman D/G 0.03) and very narrow diameter range (0.8-2.5 nm). This can be achieved by the control of catalyst precursor decomposition and subsequent formation of homogeneous nano-sized catalyst particles. PMID:24492677

  8. Application Of High Conductivity Carbon Fibre Materials For Flexible Thermal Straps

    NASA Astrophysics Data System (ADS)

    Usinger, R.; Delouard, P.; Miller, G.

    2012-07-01

    In a recently completed ESA GSTP project RUAG Space successfully demonstrated that thermal straps made from high conductivity carbon fibres can provide larger heat transport capability than conventional metallic designs at reduced mass. To prove the feasibility of the concept, breadboard models of flexible carbon fibre straps were manufactured and tested in laboratory environment. The end- to-end conductance measured in a thermal vacuum test correlated well with the prediction made with a simple thermal mathematical model. Mechanical tests were performed on the straps to check whether and to which extent the thermal performance is degraded by mechanical loads. The results from these tests indicate that the selected strap design is surprisingly tolerant against mechanical damage.

  9. Ultra-pure single wall carbon nanotube fibres continuously spun without promoter

    PubMed Central

    Paukner, Catharina; Koziol, Krzysztof K. K.

    2014-01-01

    We report a new strategy towards the control of carbon nanotube (CNT) structure and continuous fibre formation using a floating catalyst direct spinning CVD process. In the procedures used to date, a sulphur promoter precursor is added to significantly enhance the rate of CNT formation in the floating catalyst synthesis. Within the reaction zone, the rapidly grown nanotubes self-assemble into bundles, followed by their continuous spinning into fibres, yarns, films or tapes. In this paper we demonstrate a catalyst control strategy in the floating catalyst system, where the CNT formation process is independent of the presence of a promoter but leads to successful spinning of the macroscopic carbon nanotube assemblies with specific morphology, high purity (Raman D/G 0.03) and very narrow diameter range (0.8–2.5 nm). This can be achieved by the control of catalyst precursor decomposition and subsequent formation of homogeneous nano-sized catalyst particles. PMID:24492677

  10. Influence of bulk fibre properties of PAN-based carbon felts on their performance in vanadium redox flow batteries

    NASA Astrophysics Data System (ADS)

    Schweiss, Rüdiger

    2015-03-01

    Polyacrylonitrile (PAN)-based carbon felts with different fibre properties were studied in terms of their suitability as porous flow-through electrode materials in all vanadium redox flow batteries. The crystallinity and their bulk hetero element content (in particular nitrogen) of the carbon fibres was shown to produce a significant effect on the electrocatalytical properties of the electrodes towards vanadium species. Similar effects were seen on the capacity losses associated with concomitant hydrogen evolution. Adjustments of fibre properties offer the potential of manufacturing improved electrode materials, potentially without additional steps such as surface activation or decoration with catalytically active species.

  11. Reconstruction of the anterior cruciate ligament with carbon fibres: unsatisfactory results after 8 years.

    PubMed

    Mäkisalo, S E; Visuri, T; Viljanen, A; Jokio, P

    1996-01-01

    A total of 37 patients were operated on for anterior cruciate ligament (ACL) insufficiency between 1980 and 1989 using two types of carbon fibre ligament substitutes. The average age of the population was 23.6 years. The carbon fibre prostheses were covered with either a strip of medial joint capsule or lyophilized dura. Follow-up averaged 8.1 years (range 4-13 years), most of the operations being done from 1983 to 1985. Evaluation included a questionnaire, physical examination, Lysholm scoring, radiographs and cruciometer testing. The operated ACLs were looser than those in the contralateral healthy knees. The Lysholm scoring system gave acceptable results (excellent and good) in 43.5%, fair in 31.4% and poor in 24.1% of cases. Acceptable results provided better stability and muscle strength. During the follow-up there was an evident deterioration in stability as well as in Lysholm score. The results between the two types of ligaments did not become statistically different. Osteoarthrosis increased in all the knees examined radiographically (28/37). The results indicate that the ACL reconstructions using these types of carbon fibre prostheses lead to unacceptable results in the long-term follow-up.

  12. Study on residual stress in carbon fibres by Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Liu, Hanchen; Wang, Qiuping; Wu, Junfang; Zhang, Chonghui; Wang, Jing; Tang, Yuanhe

    2008-12-01

    Based on the principle that residual stress in crystal lattice leads to change of distance among atoms, an approximate linear relationship between Raman shift and suffered strain of fibers is deduced. According to the stress-strain curve, a linear relationship between the stress and Raman shift is also deduced, and the ratio coefficient of the stress and Raman frequency shift is given. In high intensity carbon fibers, different spectra of the carbon fibers are obtained by Raman spectroscopy. The approximate linear relationship between the carbon fiber tensile strain and Raman shift is validated and the stress factor is given as well. Both the theoretic and experimental results show that the stress factor is -486.7GPa.mm. The experiment results also show that the Raman spectroscopy is a very effective method for the microstructure residual stress measurement. This method for residual stress measurement by Raman shift is able to be used in textile, biology, materials etc..

  13. Effect of plasma parameters on growth and field emission properties of spherical carbon nanotube tip

    SciTech Connect

    Sharma, Suresh C.; Tewari, Aarti

    2011-06-15

    The effect of plasma parameters (e.g., electron density and temperature, ion density and temperature, neutral atom density and temperature) on the growth (without a catalyst), structure, and field emission properties of a spherical carbon nanotube (CNT) tip has been theoretically investigated. A theoretical model of charge neutrality, including the kinetics of electrons, positively charged ions, and neutral atoms and the energy balance of the various species in plasma, has been developed. Numerical calculations of the radius of the spherical CNT tip for different CNT number densities and plasma parameters have been carried out for the typical glow discharge plasma parameters. It is found that upon an increase in the CNT number density and plasma parameters, the radius of the spherical CNT tip decreases, and consequently the field emission factor for the spherical CNT tip increases.

  14. The use of rivets for electrical resistance measurement on carbon fibre-reinforced thermoplastics

    NASA Astrophysics Data System (ADS)

    DeBaere, I.; Van Paepegem, W.; Degrieck, J.

    2007-10-01

    The use of fibre-reinforced thermoplastics, for example in the aeronautical industry, is increasing rapidly. Therefore, there is an increasing need for in situ monitoring tools, which preferably have limited influence on the behaviour of the material and which are easy to use. Furthermore, in the aeronautical industry composites are very often attached with rivets. In this study, the possibility of the use of rivets as contact electrodes for electrical resistance measurement is explored. The material used is a carbon fibre-reinforced polyphenylene sulphide. First, the set-up used is discussed. Then, static tensile tests on the laminate are performed. The possible influence of an extensometer on the measurements is examined. Furthermore, failure predictability is assessed. It may be concluded that the proposed set-up with the rivets can be used for electrical resistance measurement, with the ability to predict failure, and that the extensometer has a negative influence on the resistance measurement.

  15. Recycling carbon fibre reinforced polymers for structural applications: technology review and market outlook.

    PubMed

    Pimenta, Soraia; Pinho, Silvestre T

    2011-02-01

    Both environmental and economic factors have driven the development of recycling routes for the increasing amount of carbon fibre reinforced polymer (CFRP) waste generated. This paper presents a review of the current status and outlook of CFRP recycling operations, focusing on state-of-the-art fibre reclamation and re-manufacturing processes, and on the commercialisation and potential applications of recycled products. It is shown that several recycling and re-manufacturing processes are reaching a mature stage, with implementations at commercial scales in operation, production of recycled CFRPs having competitive structural performances, and demonstrator components having been manufactured. The major challenges for the sound establishment of a CFRP recycling industry and the development of markets for the recyclates are summarised; the potential for introducing recycled CFRPs in structural components is discussed, and likely promising applications are investigated.

  16. Computational local stiffness analysis of biological cell: High aspect ratio single wall carbon nanotube tip.

    PubMed

    TermehYousefi, Amin; Bagheri, Samira; Shahnazar, Sheida; Rahman, Md Habibur; Kadri, Nahrizul Adib

    2016-02-01

    Carbon nanotubes (CNTs) are potentially ideal tips for atomic force microscopy (AFM) due to the robust mechanical properties, nanoscale diameter and also their ability to be functionalized by chemical and biological components at the tip ends. This contribution develops the idea of using CNTs as an AFM tip in computational analysis of the biological cells. The proposed software was ABAQUS 6.13 CAE/CEL provided by Dassault Systems, which is a powerful finite element (FE) tool to perform the numerical analysis and visualize the interactions between proposed tip and membrane of the cell. Finite element analysis employed for each section and displacement of the nodes located in the contact area was monitored by using an output database (ODB). Mooney-Rivlin hyperelastic model of the cell allows the simulation to obtain a new method for estimating the stiffness and spring constant of the cell. Stress and strain curve indicates the yield stress point which defines as a vertical stress and plan stress. Spring constant of the cell and the local stiffness was measured as well as the applied force of CNT-AFM tip on the contact area of the cell. This reliable integration of CNT-AFM tip process provides a new class of high performance nanoprobes for single biological cell analysis. PMID:26652417

  17. In-situ monitoring of carbon dioxide emissions from a diesel engine using a mid-infrared optical fibre sensor

    NASA Astrophysics Data System (ADS)

    Lewis, Elfed; Clifford, John; Fitzpatrick, Colin; Dooly, Gerard; Zhao, Weizhong; Sun, Tong; Grattan, Ken; Lucas, James; Degner, Martin; Ewald, Hartmut; Lochmann, Steffan; Bramann, Gero; Merlone-Borla, Edoardo; Gili, Flavio

    2011-05-01

    A robust optical fibre based CO2 exhaust gas sensor operating in the mid infrared spectral range is described. It is capable of detecting on board carbon dioxide (CO2) emissions from both diesel and petrol engines. The optical fibre sensor is not cross sensitive to other gaseous species in the exhaust such as water vapour (H2O), carbon monoxide (CO), oxides of nitrogen (NOx) or oxides of sulphur (SOx).The response of the sensor to carbon dioxide present in the exhaust of Fiat Croma diesel engine are presented.

  18. Prediction of failure in notched carbon-fibre-reinforced-polymer laminates under multi-axial loading.

    PubMed

    Tan, J L Y; Deshpande, V S; Fleck, N A

    2016-07-13

    A damage-based finite-element model is used to predict the fracture behaviour of centre-notched quasi-isotropic carbon-fibre-reinforced-polymer laminates under multi-axial loading. Damage within each ply is associated with fibre tension, fibre compression, matrix tension and matrix compression. Inter-ply delamination is modelled by cohesive interfaces using a traction-separation law. Failure envelopes for a notch and a circular hole are predicted for in-plane multi-axial loading and are in good agreement with the observed failure envelopes from a parallel experimental study. The ply-by-ply (and inter-ply) damage evolution and the critical mechanisms of ultimate failure also agree with the observed damage evolution. It is demonstrated that accurate predictions of notched compressive strength are obtained upon employing the band broadening stress for microbuckling, highlighting the importance of this damage mode in compression. This article is part of the themed issue 'Multiscale modelling of the structural integrity of composite materials'. PMID:27242302

  19. Prediction of failure in notched carbon-fibre-reinforced-polymer laminates under multi-axial loading.

    PubMed

    Tan, J L Y; Deshpande, V S; Fleck, N A

    2016-07-13

    A damage-based finite-element model is used to predict the fracture behaviour of centre-notched quasi-isotropic carbon-fibre-reinforced-polymer laminates under multi-axial loading. Damage within each ply is associated with fibre tension, fibre compression, matrix tension and matrix compression. Inter-ply delamination is modelled by cohesive interfaces using a traction-separation law. Failure envelopes for a notch and a circular hole are predicted for in-plane multi-axial loading and are in good agreement with the observed failure envelopes from a parallel experimental study. The ply-by-ply (and inter-ply) damage evolution and the critical mechanisms of ultimate failure also agree with the observed damage evolution. It is demonstrated that accurate predictions of notched compressive strength are obtained upon employing the band broadening stress for microbuckling, highlighting the importance of this damage mode in compression. This article is part of the themed issue 'Multiscale modelling of the structural integrity of composite materials'.

  20. Large-Scale Fabrication of Carbon Nanotube Probe Tips For Atomic Force Microscopy Critical Dimension Imaging Applications

    NASA Technical Reports Server (NTRS)

    Ye, Qi Laura; Cassell, Alan M.; Stevens, Ramsey M.; Meyyappan, Meyya; Li, Jun; Han, Jie; Liu, Hongbing; Chao, Gordon

    2004-01-01

    Carbon nanotube (CNT) probe tips for atomic force microscopy (AFM) offer several advantages over Si/Si3N4 probe tips, including improved resolution, shape, and mechanical properties. This viewgraph presentation discusses these advantages, and the drawbacks of existing methods for fabricating CNT probe tips for AFM. The presentation introduces a bottom up wafer scale fabrication method for CNT probe tips which integrates catalyst nanopatterning and nanomaterials synthesis with traditional silicon cantilever microfabrication technology. This method makes mass production of CNT AFM probe tips feasible, and can be applied to the fabrication of other nanodevices with CNT elements.

  1. Effect of ultrasonically-assisted drilling on carbon-fibre-reinforced plastics

    NASA Astrophysics Data System (ADS)

    Makhdum, Farrukh; Phadnis, Vaibhav A.; Roy, Anish; Silberschmidt, Vadim V.

    2014-11-01

    This research focuses on the effect of ultrasonically-assisted drilling (UAD) on carbon fibre-reinforced plastics. High-frequency vibration was used to excite a drill bit during its standard operation. An extensive experimental study of drilling forces, temperature, chip formation, surface finish, circularity, delamination and tool wear was conducted using ∅3 mm drill and presented here. UAD showed a significant improvement in drill quality when compared to conventional drilling processes. A finite-element study was also conducted to understand the nature of drilling-force reduction in UAD.

  2. The use of short carbon fibre reinforced thermoplastic plates for fracture fixation.

    PubMed

    Gillett, N; Brown, S A; Dumbleton, J H; Pool, R P

    1985-03-01

    Thermoplastic plates of Nylon 6-10 and Polybutylene terephthalate reinforced with 30% short randomly oriented carbon fibres were tested for internal fixation of canine femoral transverse midshaft fractures. The elastic modulus of the plates was one-half that of bone: however, ultimate strength and strain in bending were comparable to bone. The fractures healed with moderate callus formation which was completely remodelled by 8 to 12 wk post surgery. Although a moderate inflammatory reaction to occasional particulate debris was noted, the materials appeared to possess the proper elastic moduli to allow sufficient support for the healing fracture without protecting the remodelling process.

  3. CARBON FIBRE COMPOSITE MATERIALS PRODUCED BY GAMMA RADIATION INDUCED CURING OF EPOXY RESINS

    SciTech Connect

    Dispenza, C.; Spadaro, G.; Alessi, S.

    2008-08-28

    It is well known that ionizing radiation can initiate polymerization of suitable monomers for many applications. In this work an epoxy difunctional monomer has been used as matrix of a carbon fibre composite in order to produce materials through gamma radiation, for aerospace and advanced automotive applications. Radiation curing has been performed at different absorbed doses and, as comparison, also thermal curing of the same monomer formulations has been done. Furthermore some irradiated samples have been also subjected to a post irradiation thermal curing in order to complete the polymerization reactions. The properties of the cured materials have been studied by moisture absorption isotherms, dynamic mechanical thermal analysis and mechanical flexural tests.

  4. A Lamb waves based statistical approach to structural health monitoring of carbon fibre reinforced polymer composites.

    PubMed

    Carboni, Michele; Gianneo, Andrea; Giglio, Marco

    2015-07-01

    This research investigates a Lamb-wave based structural health monitoring approach matching an out-of-phase actuation of a pair of piezoceramic transducers at low frequency. The target is a typical quasi-isotropic carbon fibre reinforced polymer aeronautical laminate subjected to artificial, via Teflon patches, and natural, via suitable low velocity drop weight impact tests, delaminations. The performance and main influencing factors of such an approach are studied through a Design of Experiment statistical method, considering both Pulse Echo and Pitch Catch configurations of PZT sensors. Results show that some factors and their interactions can effectively influence the detection of a delamination-like damage.

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

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

    PubMed

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

    2014-07-01

    Micro-supercapacitors are promising energy storage devices that can complement or even replace batteries in miniaturized portable electronics and microelectromechanical systems. Their main limitation, however, is the low volumetric energy density when compared with batteries. Here, we describe a hierarchically structured carbon microfibre made of an interconnected network of aligned single-walled carbon nanotubes with interposed nitrogen-doped reduced graphene oxide sheets. The nanomaterials form mesoporous structures of large specific surface area (396 m(2) g(-1)) and high electrical conductivity (102 S cm(-1)). We develop a scalable method to continuously produce the fibres using a silica capillary column functioning as a hydrothermal microreactor. The resultant fibres show a specific volumetric capacity as high as 305 F cm(-3) in sulphuric acid (measured at 73.5 mA cm(-3) in a three-electrode cell) or 300 F cm(-3) in polyvinyl alcohol (PVA)/H(3)PO(4) electrolyte (measured at 26.7 mA cm(-3) in a two-electrode cell). A full micro-supercapacitor with PVA/H(3)PO(4) gel electrolyte, free from binder, current collector and separator, has a volumetric energy density of ∼6.3 mWh cm(-3) (a value comparable to that of 4 V-500 µAh thin-film lithium batteries) while maintaining a power density more than two orders of magnitude higher than that of batteries, as well as a long cycle life. To demonstrate that our fibre-based, all-solid-state micro-supercapacitors can be easily integrated into miniaturized flexible devices, we use them to power an ultraviolet photodetector and a light-emitting diode.

  7. Low Velocity Impacts of Variable Tip Radius on Carbon/Epoxy Plates

    NASA Astrophysics Data System (ADS)

    Delaney, Mac P.

    With a growing use of composite materials in aircraft structures, there is a greater need to understand the response of these materials to low velocity impacts. Low velocity impacts from tool drops or ground equipment collisions can be of varying bluntness and can leave little or no visible evidence of damage. Therefore, a need exists to investigate the initiation of internal damage and the relationship between this internal damage and the external visible damage with respect to the bluntness of the impactor. A pendulum impactor was used to impact 76.2 x 127 mm carbon/epoxy panels that were 8, 16, and 24 plies thick. The panels were impacted by hardened steel tips with radii of 12.7 to 76.2 mm. The experimental results show that the failure threshold energies for each panel thickness and tip radius combination occur at a distinct and consistent energy. This threshold increases with impactor bluntness, and this effect is greater for the 8 ply panel than it is for the 16 or 24 ply panels. To describe the visibility of impact damage, the area of delamination was compared to the depth of the dents resulting from the impacts. For the sharper impact tips, there is a clear relationship between the delamination area and the depth of the dents. However, these relationships are dependent on the radius of the impact tip, and for the blunter impact tips no strong correlation could be determined between the delamination area and the depth of the dents.

  8. Mechanical and thermo-physical characterization of the carbon fibre composite NB31

    NASA Astrophysics Data System (ADS)

    Pintsuk, G.; Compan, J.; Linke, J.; Majerus, P.; Peacock, A.; Pitzer, D.; Rödig, M.

    2007-03-01

    The use of carbon-based materials, i.e. graphite and carbon fibre composites (CFCs), as plasma facing materials in experimental nuclear fusion devices is widely spread. For the strike point area of the ITER divertor, a European candidate material was NB31, a three directional (3D) CFC material consisting of ex-pitch, ex-PAN and needled ex-PAN fibres, which will be replaced in the future by the newly developed material NB41. This composite material is used for the fabrication of divertor components for Wendelstein 7-X. In the frame of an extensive characterization on three different material batches of NB31 called 'pilot', 'serial' and 'additional' productions for W7-X and ITER, thermo-physical measurements and tensile tests were performed. The results were correlated to density and microstructure. The latter varied due to difficulties in the manufacturing process, in particular in the needling process. Therefore the specification of a minimum density and unit cell width (combined thickness of an ex-pitch and ex-PAN layer) is necessary to meet the ITER specifications for tensile strength and for thermal conductivity in the ex-pitch direction.

  9. Modelling The Bending Test Behaviour Of Carbon Fibre Reinforced SiC By Finite Element Method

    NASA Astrophysics Data System (ADS)

    Hofmann, S.; Koch, D.; Voggenreiter, H.

    2012-07-01

    Liquid silicon infiltrated carbon fibre reinforced SiC, has shown to be a high-potential material for thermal protection systems. The tensile and bending behaviour of the ceramic-matrix composite, C/C-SiC, were investigated in varying orientations relative to the 0/90° woven carbon fibres. The ratio of bending to tensile strength was about 1.7 to 2 depending on the loading direction. With the goal to understand this large difference finite element analyses (FEA) of the bending tests were performed. The different stress-strain behaviour of C/C-SiC under tensile and compression load were included in the FEA. Additionally the bending failure of the CMC-material was modelled by Cohesive Zone Elements (CZE) accounting for the directional tensile strength and Work of Fracture (WOF). The WOF was determined by Single Edge Notched Bending (SENB) tests. Comparable results from FEA and bending test were achieved. The presented approach could also be adapted for the design of C/C-SiC-components and structures.

  10. Microstructural Characterization of Nanocrystalline Sn-Coated Carbon Fibre Electrodes Cycled in Li-Ion Cells

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Sandeep; Shafiei, Mehdi; Alpas, Ahmet T.

    2015-12-01

    The mechanisms of electrochemical capacity retention and eventual degradation in composite anodes prepared by electrodepositing nanocrystalline Sn coating on carbon fibres (CF), Sn-CF, were studied using in situ optical microscopy, high-resolution scanning and transmission electron microscopy. Specific capacity changes of Sn-CF anodes ( vs Li/Li+) were observed to take place in three stages: during the first two galvanostatic cycles, a rapid capacity decrease (from 1045 to 930 mAh g-1) occurred, which was followed by a steady-state stage where the capacity remained constant at 922 ± 22 mAh g-1. The fast capacity drop of Sn-CF in the first cycle was attributed to the partial decohesion of Sn from CFs although the carbon substrate remained unaffected due to formation of a layer from the solid electrolyte reduction products. The pure Sn electrode with a higher initial specific capacity than the Sn-CF displayed a rapid decrease in the same range, whereas the specific capacity of the uncoated CF was already much lower as the fibres were severely damaged in the first cycle.

  11. Scanning tunneling microscopy of chromium-filled carbon nanotubes: Tip effects and related topographic features

    NASA Astrophysics Data System (ADS)

    Zha, F.-X.; Czerw, R.; Carroll, D. L.; Kohler-Redlich, Ph.; Wei, B.-Q.; Loiseau, A.; Roth, S.

    2000-02-01

    We have used ultrahigh vacuum scanning tunneling microscopy (STM) to study chromium (Cr)-filled carbon nanotubes. STM micrographs show filled tubes to be less than 1 nm in height, while transmission electron microscopy indicates that Cr-filled naotubes are multiwalled with diameters generally over 10 nm. In this paper, we demonstrate that the small apparent heights are due to the STM tip status, which also accounts for the topographic anomalies observed.

  12. In-vitro MRI detectability of interbody test spacers made of carbon fibre-reinforced polymers, titanium and titanium-coated carbon fibre-reinforced polymers.

    PubMed

    Ernstberger, Thorsten; Buchhorn, Gottfried; Baums, Mike Herbert; Heidrich, Gabert

    2007-04-01

    The purpose of this study was to investigate how different materials affect the magnetic resonance imaging (MRI) detectability of interbody test spacers (ITS). We evaluated the post-implantation MRI scans with T1 TSE sequences for three different ITS made of titanium, carbon fibre-reinforced polymers (CFRP) and titanium-coated CFRP, respectively. The main target variables were total artefact volume (TAV) and median artefact area (MAA). Additionally, implant volume (IV)/TAV and cross section (CS)/MAA ratio were determined. The t test and Newman-Keuls test for multiple comparisons were used for statistical analysis. TAV and MAA did not differ significantly between CFRP and titanium-coated CFRP, but were approximately twice as high for the titanium ITS (p < 0.001). MRI detectability was optimum for CFRP and titanium-coated CFRP, but was limited at the implant-bone interface of the titanium ITS. The material's susceptibility and the implant's dimensions affected MRI artefacting. Based on TAV, the volume of titanium surface coating in the ITS studied has no influence on susceptibility in MRI scans with T1 TSE sequences.

  13. Analytical solutions to the free vibration of a double-walled carbon nanotube carrying a bacterium at its tip

    SciTech Connect

    Storch, Joel A.; Elishakoff, Isaac

    2013-11-07

    We calculate the natural frequencies and mode shapes of a cantilevered double-walled carbon nanotube carrying a rigid body—representative of a bacterium or virus—at the tip of the outer nanotube. By idealizing the nanotubes as Bernoulli-Euler beams, we are able to obtain exact expressions for both the mode shapes and characteristic frequency equation. Separate analyses are performed for the special case of a concentrated tip mass and the more complicated situation where the tip body also exhibits inertia and mass center offset from the beam tip.

  14. Sugar-Starvation-Induced Changes of Carbon Metabolism in Excised Maize Root Tips.

    PubMed Central

    Dieuaide-Noubhani, M.; Canioni, P.; Raymond, P.

    1997-01-01

    Excised maize (Zea mays L.) root tips were used to study the early metabolic effects of glucose (Glc) starvation. Root tips were prelabeled with [1-13C]Glc so that carbohydrates and metabolic intermediates were close to steady-state labeling, but lipids and proteins were scarcely labeled. They were then incubated in a sugar-deprived medium for carbon starvation. Changes in the level of soluble sugars, the respiratory quotient, and the 13C enrichment of intermediates, as measured by 13C and 1H nuclear magnetic resonance, were studied to detect changes in carbon fluxes through glycolysis and the tricarboxylic acid cycle. Labeling of glutamate carbons revealed two major changes in carbon input into the tricarboxylic acid cycle: (a) the phosphoenolpyruvate carboxylase flux stopped early after the start of Glc starvation, and (b) the contribution of glycolysis as the source of acetyl-coenzyme A for respiration decreased progressively, indicating an increasing contribution of the catabolism of protein amino acids, fatty acids, or both. The enrichment of glutamate carbons gave no evidence for proteolysis in the early steps of starvation, indicating that the catabolism of proteins was delayed compared with that of fatty acids. Labeling of carbohydrates showed that sucrose turnover continues during sugar starvation, but gave no indication for any significant flux through gluconeogenesis. PMID:12223877

  15. Modeling of Electronic Transport in Scanning Tunneling Microscope Tip-Carbon Nanotube Systems

    NASA Technical Reports Server (NTRS)

    Yamada, Toshishige; Kwak, Dochan (Technical Monitor)

    2000-01-01

    A model is proposed for two observed current-voltage (I-V) patterns in a recent experiment with a scanning tunneling microscope tip and a carbon nanotube. We claim that there are two mechanical contact modes for a tip (metal) -nanotube (semiconductor) junction (1) with or (2) without a tiny vacuum gap (0.1 - 0.2 nm). With the tip grounded, the tunneling case in (1) would produce large dI/dV with V > 0, small dI/dV with V < 0, and I = 0 near V = 0 for an either n- or p-nanotube; the Schottky mechanism in (2) would result in I does not equal 0 only with V < 0 for an n-nanotube, and the bias polarities would be reversed for a p-nanotube. The two observed I-V patterns are thus entirely explained by a tip-nanotube contact of the two types, where the nanotube must be n-type.

  16. Can carbon fibres work as tool electrodes in micro electrical discharge machining?

    NASA Astrophysics Data System (ADS)

    Trych-Wildner, Anna; Kudla, Leszek

    2016-07-01

    This paper presents a basic study of the possible application of carbon fibres as tool electrodes in micro electrical discharge machining. The purpose of the experiments with this novel material was to gain knowledge about the operation of the new tool electrode. In the paper, the procedure for adapting a single fibre to such a function is described, with detailed steps on preparing the shanks essential for the mounting operation in the experimental setup. The design setup is also presented and the experimental conditions of each test are shown. Furthermore, tests with the prepared electrodes concerning the general observations of the process and the results on the machined surface and on the tool are presented. The shape cavity fabrication and tests with the reverse polarity of the electrodes are also introduced. Next, the influence of single discharge energy is considered and the geometry of the obtained microholes is discussed. Detailed data about the wear of the tool, which can be up to 90% of the entire eroded material, in comparison with the material removal rate from the workpiece, which can be at a level of 10%, is gathered. Then, the geometrical analysis of the cavities is described showing that their depths are in the range of a few micrometres.

  17. Long-term compressive property durability of carbon fibre-reinforced polyetheretherketone composite in physiological saline.

    PubMed

    Zhang, G; Latour, R A; Kennedy, J M; Del Schutte, H; Friedman, R J

    1996-04-01

    In total hip arthroplasty, concerns such as corrosion and stress shielding associated with stiff metallic femoral components have led to the development of low stiffness advanced fibre-reinforced polymer (FRP) composite femoral components. Carbon fibre-reinforced polyetheretherketone (CF/PEEK) composite material is now one of the primary material systems being considered for composite hip stem development. As a hip stem, a composite material must be able to support a complex state of stress in the in vivo environment without failure. Considering the loading conditions of a hip stem (superimposed compression and bending), and the fact that FRP composites typically possess lower compressive than tensile strength, the compressive behaviour of FRP composites becomes very important for femoral component design. This paper presents an investigation of the long-term durability of 0 degree and 90 degrees compressive strengths of CF/PEEK composite following physiological saline saturation. 0 degree and 90 degrees compressive moduli and Poisson ratio (v12) properties are also reported. Samples were tested following conditioning in physiological saline at 37, 65 and 95 degrees C for time periods from 0 to 5000 h. Dry samples were tested as controls. Results show no significant loss in compressive property values of the saline-saturated or the dry control samples as a function of conditioning time or temperature. PMID:8730962

  18. Spinning of carbon nanotube fibres using the floating catalyst high temperature route: purity issues and the critical role of sulphur.

    PubMed

    Gspann, T S; Smail, F R; Windle, A H

    2014-01-01

    The CVD process for the spinning of carbon nanotube (CNT) fibres combines the nucleation, growth and aggregation of CNTs in the form of an aerogel with fibre spinning into a single process step. The optimisation of the process requires agility in multi-dimensional parameter space, so one tends to find parameter 'islands' where spinning is possible, while exploration tends to follow 'routes' through this space. Here, we follow two such routes, one of which drastically improves fibre purity, the other changes the nature of the nanotubes comprising the fibres from multiwall to single wall. In the first case there is only a modest enhancement of the mechanical properties, but in the second a very considerable improvement is seen. In terms of the conditions required to make fibres comprising predominately single wall CNTs, the key factor appears to be the rigorous control of the sulphur addition, in trace quantities, coupled with the availability of carbon atoms at the earliest stage after injection, typically in the range 400-500 °C. A model is presented for the role of sulphur in floating catalysts CNT synthesis. PMID:25341017

  19. Spinning of carbon nanotube fibres using the floating catalyst high temperature route: purity issues and the critical role of sulphur.

    PubMed

    Gspann, T S; Smail, F R; Windle, A H

    2014-01-01

    The CVD process for the spinning of carbon nanotube (CNT) fibres combines the nucleation, growth and aggregation of CNTs in the form of an aerogel with fibre spinning into a single process step. The optimisation of the process requires agility in multi-dimensional parameter space, so one tends to find parameter 'islands' where spinning is possible, while exploration tends to follow 'routes' through this space. Here, we follow two such routes, one of which drastically improves fibre purity, the other changes the nature of the nanotubes comprising the fibres from multiwall to single wall. In the first case there is only a modest enhancement of the mechanical properties, but in the second a very considerable improvement is seen. In terms of the conditions required to make fibres comprising predominately single wall CNTs, the key factor appears to be the rigorous control of the sulphur addition, in trace quantities, coupled with the availability of carbon atoms at the earliest stage after injection, typically in the range 400-500 °C. A model is presented for the role of sulphur in floating catalysts CNT synthesis.

  20. Cutting forces in ultrasonically assisted drilling of carbon fibre-reinforced plastics

    NASA Astrophysics Data System (ADS)

    Makhdum, Farrukh; Jennings, Luke T.; Roy, Anish; Silberschmidt, Vadim V.

    2012-08-01

    Ultrasonically assisted drilling (UAD) is a non-traditional hybrid machining process, which combines features of conventional drilling and vibratory machining techniques to obtain remarkable improvements in machinability of advanced materials. The experiments are conducted on commercially available samples of a carbon fibre-reinforced plastic (CFRP) at a feed rate of 16 mm/min. In this study, a thrust force reduction in excess of 60% is observed in UAD when compared to conventional drilling (CD). Lower delamination was observed when compared to CD techniques. Optical microscopy revealed that the material is removed as a continuous chip in UAD whereas in case of CD we observe powdered dust. Light and scanning electron microscopy of CFRP chips obtained in drilling elucidate fundamental differences in the underlying machining processes in UAD of CFRP.

  1. High-power picosecond laser drilling/machining of carbon fibre-reinforced polymer (CFRP) composites

    NASA Astrophysics Data System (ADS)

    Salama, A.; Li, L.; Mativenga, P.; Sabli, A.

    2016-02-01

    The large differences in physical and thermal properties of the carbon fibre-reinforced polymer (CFRP) composite constituents make laser machining of this material challenging. An extended heat-affected zone (HAZ) often occurs. The availability of ultrashort laser pulse sources such as picosecond lasers makes it possible to improve the laser machining quality of these materials. This paper reports an investigation on the drilling and machining of CFRP composites using a state-of-the-art 400 W picosecond laser system. Small HAZs (<25 µm) were obtained on the entry side of 6-mm-diameter hole drilled on sample of 6 mm thickness, whereas no HAZ was seen below the top surface on the cut surfaces. Multiple ring material removal strategy was used. Furthermore, the effect of laser processing parameters such as laser power, scanning speed and repetition rate on HAZ sizes and ablation depth was investigated.

  2. Numerical modelling of thermal decomposition processes and associated damage in carbon fibre composites

    NASA Astrophysics Data System (ADS)

    Chippendale, R. D.; Golosnoy, I. O.; Lewin, P. L.

    2014-09-01

    Thermo-chemical degradation of carbon fibre composite (CFC) materials under intensive heat fluxes are modelled. The model couples together heat diffusion, polymer pyrolysis with associated gas production and convection through partially decomposed CFCs, and changes in transport properties of the material due to the damage. The model is verified by laser ablation experiments with controlled heat input. The numerical predictions indicate that the thermal gas transport has a minimal effect on the decomposition extent. On the other hand, the model shows that the internal gas pressure is large enough to cause fracture and delamination, and the damage extent may go far beyond the decomposition region as witnessed from experimental verification of the model.

  3. Rigidity and retention of carbon fibre versus stainless steel root canal posts.

    PubMed

    Purton, D G; Love, R M

    1996-07-01

    Two of the main requirements of a root canal post are that it is rigid so as to resist flexing under functional load, and that it is well retained in the root. This study compared these properties in two different 1-mm diameter root canal posts--smooth carbon fibre posts (Endopost) and serrated stainless steel posts (Parapost). Ten posts of each type were tested for rigidity in a three-point bend test. Ten posts of each type were cemented with resin cement into the roots of endodontically treated, extracted teeth. The tensile force required to remove the posts was recorded. The Paraposts proved to be significantly more rigid under load (P < 0.001) and significantly more strongly retained in the tooth roots (P < 0.005). The Parapost appears to be a mechanically superior post for the restoration of root-filled teeth with narrow diameter root canals. PMID:9206443

  4. Milling damage on Carbon Fibre Reinforced Polymer using TiAlN coated End mills

    NASA Astrophysics Data System (ADS)

    Konneh, Mohamed; Izman, Sudin; Rahman Kassim, Abdullah Abdul

    2015-07-01

    This paper reports on the damage caused by milling Carbon Fibre Reinforced Composite (CFRP) with 2-flute 4 mm-diameter solid carbide end mills, coated with titanium aluminium nitride. The machining parameters considered in work are, rotation speed, feed rate and depth of cut. Experiments were designed based on Box-Behnken design and the experiments conducted on a Mikrotool DT-110 CNC micro machine. A laser tachometer was used to ascertain a rotational speed for conducting any machining trial. Optical microscopy examination reveals minimum delamination value of 4.05 mm at the spindle speed of 25,000 rpm, depth of cut of 50μm and feed rate of 3 mm/min and the maximum delamination value of 5.04 mm at the spindle speed of 35000 rpm, depth of cut of 150μm and feed rate of 9 mm/min A mathematical model relating the milling parameters and delamination has been established.

  5. Flexural testing on carbon fibre laminates taking into account their different behaviour under tension and compression

    NASA Astrophysics Data System (ADS)

    Serna Moreno, M. C.; Romero Gutierrez, A.; Martínez Vicente, J. L.

    2016-07-01

    An analytical model has been derived for describing the results of three-point-bending tests in materials with different behaviour under tension and compression. The shift of the neutral plane and the damage initiation mode and its location have been defined. The validity of the equations has been reviewed by testing carbon fibre-reinforced polymers (CFRP), typically employed in different weight-critical applications. Both unidirectional and cross-ply laminates have been studied. The initial failure mode produced depends directly on the beam span- thickness relation. Therefore, specimens with different thicknesses have been analysed for examining the damage initiation due to either the bending moment or the out-of-plane shear load. The experimental description of the damage initiation and evolution has been shown by means of optical microscopy. The good agreement between the analytical estimations and the experimental results shows the validity of the analytical model exposed.

  6. Repeated self-healing of microvascular carbon fibre reinforced polymer composites

    NASA Astrophysics Data System (ADS)

    Coope, T. S.; Wass, D. F.; Trask, R. S.; Bond, I. P.

    2014-11-01

    A self-healing, high performance, carbon fibre reinforced polymer (CFRP) composite is demonstrated by embedding a Lewis-acid catalytic curing agent within a laminate, manufactured using out of autoclave (OOA) composite manufacturing methods. Two configurations of healing agent delivery, pre-mixed and autonomous mixing, are investigated via injection of a healing agent through bio-inspired microvascular channels exposed on Mode I fractured crack planes. Healing is effected when an epoxy resin-solvent healing agent mixture reaches the boundary of embedded solid-state scandium(III) triflate (Sc(OTf)3) catalyst, located on the crack plane, to initiate the ring-opening polymerisation (ROP) of epoxides. Tailored self-healing agents confer high healing efficiency values after multiple healing cycles (69-108%) to successfully mitigate against crack propagation within the composite microstructure.

  7. Characterization of field emission from carbon nanofibers on a metal tip

    NASA Astrophysics Data System (ADS)

    Sakai, Y.; Tone, D.; Nagatsu, S.; Endo, T.; Kita, S.; Okuyama, F.

    2009-08-01

    Field electron emission from carbon nanofibers (CNFs) grown on a tungsten tip has been characterized by measuring emission current-voltage (I-V) curves and observing emission patterns on a phosphor screen. CNFs were vertically grown on the tip by plasma-enhanced chemical vapor deposition. Field emission from the CNFs over 100 μA was strongly dependent on emitter-anode distance, and the dominant field electrons were emitted within an angular spread of Δθ ˜25°, indicating the electron emission took place mainly from the emitter's apex area. By analyzing the I-V curves with the aid of the Fowler-Nordheim theory, the maximum current density was estimated to be about J =2×109 A/m2.

  8. Tip-Enhanced Raman Spectroscopic Imaging of Individual Carbon Nanotubes with Subnanometer Resolution.

    PubMed

    Liao, Menghan; Jiang, Song; Hu, Chunrui; Zhang, Rui; Kuang, Yanmin; Zhu, Jiazhe; Zhang, Yang; Dong, Zhenchao

    2016-07-13

    Individual carbon nanotubes (CNTs) have been investigated by tip-enhanced Raman spectroscopy (TERS) using silver tips on the Ag(111) substrate with a low-temperature ultrahigh-vacuum scanning tunneling microscope. Thanks to the strong and highly localized plasmonic field offered by the silver nanogap, the spatial resolution of TERS on CNTs is driven down to about 0.7 nm. Such a high spatial resolution allows to visualize in real space the spatial extent of the defect-induced D-band scattering, to track the strain-induced spectral evolution, and to resolve the spectral differences between the inner and the outer sides of a bent CNT, all at the nanometer scale. PMID:27348072

  9. CRACK TIP OPENING DISPLACEMENT AND ANGLE FOR A GROWING CRACK IN CARBON STEEL

    SciTech Connect

    LAM, POH-SANG

    2005-01-18

    The crack tip opening displacements and angles (CTOD/CTOA) are calculated with finite element method based on the test data of a set of constraint-dependent J-R curves for A285 carbon steel. The values of the CTOD/CTOA are initially high at initiation, but rapidly decrease to a nearly constant value. When the common practice is adopted by using only the constant part of CTOD/CTOA as the fracture criterion, the crack growth behavior is shown to be severely underestimated. However, with a bilinear form of CTOD/CTOA fracture criterion which approximates the initial non-constant portion, the experimental load vs. crack extension curves can be closely predicted. Furthermore, it is demonstrated that the CTOD/CTOA is crack tip constraint dependent. The values of CTOD/CTOA for specimens with various ratios of crack length to specimen width (a/W) are reflected by the J-R curves and their slopes.

  10. An estimation of fatigue life for a carbon fibre/poly ether ether ketone hip joint prosthesis.

    PubMed

    Akay, M; Aslan, N

    1995-01-01

    A fracture mechanics approach was applied to estimate the life of a prosthesis injection moulded from short carbon fibre reinforced poly ether ether ketone. Flexural modulus and strength, fracture toughness, fatigue endurance limit, fatigue crack growth rate and threshold stress intensity factor were determined. The dimensions of the test pieces were selected to yield fibre orientation and fibre length distributions similar to those obtained in the prosthesis. Stress levels generated in the prosthesis under different activities were estimated by conducting three-dimensional finite element analysis. It was shown by a fracture mechanics approach that a fatigue failure due to the propagation of an embedded elliptical slit, under these stresses, would be unlikely for a crack length smaller than 1.85 mm. However, the cement would fail under the same conditions, irrespective of the type of the prosthesis employed.

  11. Optimization of basic dye removal by oil palm fibre-based activated carbon using response surface methodology.

    PubMed

    Hameed, B H; Tan, I A W; Ahmad, A L

    2008-10-30

    Oil palm fibre was used to prepare activated carbon using physiochemical activation method which consisted of potassium hydroxide (KOH) treatment and carbon dioxide (CO(2)) gasification. The effects of three preparation variables: the activation temperature, activation time and chemical impregnation (KOH:char) ratio on methylene blue (MB) uptake from aqueous solutions and activated carbon yield were investigated. Based on the central composite design (CCD), a quadratic model and a two factor interaction (2FI) model were respectively developed to correlate the preparation variables to the MB uptake and carbon yield. From the analysis of variance (ANOVA), the significant factors on each experimental design response were identified. The optimum activated carbon prepared from oil palm fibre was obtained by using activation temperature of 862 degrees C, activation time of 1h and chemical impregnation ratio of 3.1. The optimum activated carbon showed MB uptake of 203.83 mg/g and activated carbon yield of 16.50%. The equilibrium data for adsorption of MB on the optimum activated carbon were well represented by the Langmuir isotherm, giving maximum monolayer adsorption capacity as high as 400mg/g at 30 degrees C. PMID:18329169

  12. Investigating of the Field Emission Performance on Nano-Apex Carbon Fiber and Tungsten Tips

    NASA Astrophysics Data System (ADS)

    Mousa, Marwan S.; Alnawasreh, Shadi; Madanat, Mazen A.; Al-Rabadi, Anas N.

    2015-10-01

    Field electron emission measurements have been performed on carbon-based and tungsten microemitters. Several samples of both types of emitters with different apex radii have been obtained employing electrolytic etching techniques using sodium hydroxide (NaOH) solution with different molarities depending on the material used. A suitable, home-built, field electron microscope (FEM) with 10 mm tip to screen separation distance was used to electrically characterize the electron emitters. Measurements were carried out under ultra high vacuum (UHV) conditions with base pressure of 10-9 mbar. The current-voltage characteristics (I-V) presented as Fowler-Nordheim (FN) type plots, and field electron emission images have been recorded. In this work, initial comparison of the field electron emission performance of these micro and nanoemitters has been carried out, with the aim of obtaining a reliable, stable and long life powerful electron source. We compare the apex radii measured from the micrographs obtained from the SEM images to those extracted from the FN-type _I-V_plots for carbon fibers and tungsten tips.

  13. The influence of compliant chassis components on motorcycle dynamics: an historical overview and the potential future impact of carbon fibre

    NASA Astrophysics Data System (ADS)

    Lake, Kelvin; Thomas, Richard; Williams, Owen

    2012-07-01

    This paper details the influence of compliant chassis components on motorcycle dynamics. Initially, research which has previously been carried out in terms of motorcycle dynamics and in particular the impact of compliant chassis components on motorcycle dynamics is discussed. This paper then considers the consequences of these findings with regard to the use of modern materials such as carbon fibre reinforced plastics and the impact they will potentially have on motorcycle dynamics and its simulation.

  14. Non-destructive testing of satellite nozzles made of carbon fibre ceramic matrix composite, C/SiC

    SciTech Connect

    Rebelo Kornmeier, J. Hofmann, M.; Schmidt, S.

    2007-10-15

    Carbon fibre ceramic matrix composite materials, C/SiC, are excellent candidates as lightweight structural materials for high performance hot structures such as in aerospace applications. Satellite nozzles are manufactured from C/SiC, using, for instance, the Liquid Polymer Infiltration (LPI) process. In this article the applicability of different non-destructive analysis methods for the characterisation of C/SiC components will be discussed. By using synchrotron and neutron tomography it is possible to characterise the C/SiC material in each desired location or orientation. Synchrotron radiation using tomography on small samples with a resolution of 1.4 {mu}m, i.e. the fibre scale, was used to characterise three dimensionally fibre orientation and integrity, matrix homogeneity and dimensions and distributions of micro pores. Neutron radiation tomography with a resolution of about 300 {mu}m was used to analyse the over-all C/SiC satellite nozzle component with respect to the fibre content. The special solder connection of a C/SiC satellite nozzle to a metallic ring was also successfully analysed by neutron tomography. In addition, the residual stress state of a temperature tested satellite nozzle was analysed non-destructively in depth by neutron diffraction. The results revealed almost zero stress for the principal directions, radial, axial and tangential, which can be considered to be the principal directions.

  15. On longitudinal compressive failure of carbon-fibre-reinforced polymer: from unidirectional to woven, and from virgin to recycled.

    PubMed

    Pinho, S T; Gutkin, R; Pimenta, S; De Carvalho, N V; Robinson, P

    2012-04-28

    Modelling the longitudinal compressive failure of carbon-fibre-reinforced composites has been attempted for decades. Despite many developments, no single model has surfaced to provide simultaneously a definitive explanation for the micromechanics of failure as well as validated predictions for a generic stress state. This paper explores the reasons for this, by presenting experimental data (including scanning electron microscopic observations of loaded kink bands during propagation, and brittle shear fracture at 45° to the fibres) and reviewing previously proposed micromechanical analytical and numerical models. The paper focuses mainly on virgin unidirectional (UD) composites, but studies for woven and recycled composites are also presented, highlighting similarities and differences between these cases. It is found that, while kink-band formation (also referred to in the literature as microbuckling) is predominant in UD composites under longitudinal compression, another failure mode related to the failure of the fibres can be observed experimentally. It is also shown that the micromechanics of the failure process observed in UD composites is similar to that in other fibre architectures, hence encouraging the adaptation and application of models developed for the former to the latter.

  16. Cryogenic performances of T700 and T800 carbon fibre- epoxy laminates

    NASA Astrophysics Data System (ADS)

    Wei, Wang; Rongjin, Huang; Chuanjun, Huang; Zhao, Yuqiang; Li, Shaopeng; Laifeng, Li

    2015-12-01

    The temperature dependence of thermal expansion, thermal conductivity and mechanical properties of T700 carbon fibre (T700 CFs) /epoxy composite and T800 CF/epoxy composite were investigated. The mechanical and thermal properties of the unidirectional composite material laminates (0°/90°) at low temperature were studied. The results show that comparing the composite material T700 CFs with T800 CFs, the thermal expansion and thermal conductivity performances of T800 CFs (0°/90°) are all smaller than those of T700 CFs. Typically, the coefficient of thermal expansion (CTE) of T800 CFs in 0° is very low in the temperature range of 120-300K, which reaches as low as -0.4×10-6 K-1. The value of thermal conductivity of this material at 0° is about 3.2 W.(m.K)-1 at room temperature. Tensile and compression tests indicate that the tensile strength of T800 CFs in 0° direction at 77K reaches 2310 MPa, while the compressive strength is about 852 MPa. This composite material may possibly be exploited to design the critical components for practical applications such as hydrogen storage tanks.

  17. Assessment of carbon fibre composite fracture fixation plate using finite element analysis.

    PubMed

    Saidpour, Seyed H

    2006-07-01

    In the internal fixation of fractured bone by means of bone-plates fastened to the bone on its tensile surface, an on-going concern has been the excessive stress shielding of the bone by the excessively-stiff stainless-steel plate. The compressive stress shielding at the fracture-interface immediately after fracture-fixation delays callus formation and bone healing. Likewise, the tensile stress shielding in the layer of bone underneath the plate can cause osteoporosis and decrease in tensile strength of this layer. In this study a novel forearm internal fracture fixation plate made from short carbon fibre reinforced plastic (CFRP) was used in an attempt to address the problem. Accordingly, it has been possible to analyse the stress distribution in the composite plates using finite-element modelling. A three-dimensional, quarter-symmetric finite element model was generated for the plate system. The stress state in the underlying bone was examined for several loading conditions. Based on the analytical results the composite plate system is likely to reduce stress-shielding effects at the fracture site when subjected to bending and torsional loads. The design of the plate was further optimised by reducing the width around the innermost holes.

  18. Hidden defect identification in carbon fibre reinforced polymer plates using magnetic induction tomography

    NASA Astrophysics Data System (ADS)

    Ma, Lu; Soleimani, Manuchehr

    2014-05-01

    Carbon fibre reinforced polymer (CFRP) materials pose new challenges to the non-destructive evaluation (NDE) techniques. This study addresses the issue of large defect identification in CFRP plates using electromagnetic measurements. A dual plane magnetic induction tomography (MIT) technique is proposed as a method for damage localization in composite parts, where two arrays of planar sensors are utilized to measure the changes in induced voltages due to the changes in electrical conductivity properties. This geometry meets the requirements of damage inspection in plate structures and thus makes the imaging process feasible. The electrical voltage measurements are used as input to inversely map the spatial resolution of the samples in the region of interest. The stability and detectability of the dual plane system is examined using small metallic cubes. Both individual and multiple instances of damage embedded in CFRP samples are created as a representation of the possible manufacturing defects. Experimental study shows that the presence of damage can be identified in both cases using the dual plane MIT system. With advanced sensing design, rapid data collection unit and improvement in resolution, MIT could become a rapid NDE technique for the integrity inspection of composite structures.

  19. Effects of activated carbon fibre-supported metal oxide characteristics on toluene removal.

    PubMed

    Liu, Zhen-Shu; Peng, Yu-Hui; Li, Wen-Kai

    2014-01-01

    Few studies have investigated the use of activated carbon fibres (ACFs) impregnated with metal oxides for the catalytic oxidation of volatile organic compounds (VOCs). Thus, the effects of the ACF-supported metal oxides on toluene removal are determined in this study. Three catalysts, namely, Ce, Mn, and Cu, two pretreatment solutions NaOH and H2O2, and three reaction temperatures of 250 degrees C, 300 degrees C, and 350 degrees C, were employed to determine toluene removal. The composition and morphology of the catalysts were analysed using Brunauer-Emmett-Teller (BET), transmission electron microscope (TEM), inductively coupled plasma (ICP), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectrometer (FTIR), and thermo-gravimetric analyser (TGA) to study the effects of the catalyst's characteristics on toluene removal. The results demonstrated that the metal catalysts supported on the ACFs could significantly increase toluene removal. The Mn/ACFs and Cu/ACFs were observed to be most active in toluene removal at a reaction temperature of 250 degrees C with 10% oxygen content. Moreover, the data also indicated that toluene removal was slightly improved after pretreating the ACFs with NaOH and H2O2. The results suggested that surface-metal loading and the surface characteristics of the ACFs were the determinant parameters for toluene removal. Furthermore, the removal of toluene over Mn/ACFs-H202 decreased when the reaction temperature considered was > 300 degrees C.

  20. Universal field-emission model for carbon nanotubes on a metal tip

    NASA Astrophysics Data System (ADS)

    Zhong, D. Y.; Zhang, G. Y.; Liu, S.; Sakurai, T.; Wang, E. G.

    2002-01-01

    Electron-field-emission properties have been investigated systematically for carbon nanotubes (CNTs) fabricated on a metal tip. With a vacuum gap of 0.7 mm, the threshold field is as low as 0.7 V/μm and the current density approaches 10 mA/cm2 at an electronic field of 1.0 V/μm. The emission current is quite stable with very low fluctuation. The emission behavior is in excellent agreement with Fowler-Nordheim theory and no current saturation is found even with an emission current reaching 1 A/cm2. A universal relationship 1/β=d2/d+1/β0 between the field amplification factor β and the vacuum gap d is developed within a two-region field-emission model. This relationship provides the basis for a microscopic understanding of CNT emitters and is applicable to other systems as well.

  1. Biomechanical analysis using infrared thermography of a traditional metal plate versus a carbon fibre/epoxy plate for Vancouver B1 femur fractures.

    PubMed

    Siddiqui, Faisal S; Shah, Suraj; Nicayenzi, Bruce; Schemitsch, Emil H; Zdero, Radovan; Bougherara, Habiba

    2014-01-01

    Traditional high-stiffness metal plates for Vancouver B1 femur shaft fractures below the tip of a hip implant can cause stress shielding, bone resorption, and implant loosening. This is the first study to compare the biomechanics of a traditional metal plate versus a low-stiffness carbon fibre/epoxy composite plate for this injury. A total hip replacement was implanted in two previously validated intact artificial femurs. Femurs were fitted with either a metal or composite plate and had a 5 mm fracture gap created to simulate a Vancouver B1 shaft fracture. Femurs were cyclically loaded using 5 Hz at 7° of adduction with an average axial load of 800 N (range = 400-1200 N). Overall mechanical stiffnesses and femur and plate thermographic stresses were obtained. Femur/metal plate stiffness (698 N/mm) was only 12% higher than femur/composite plate stiffness (625 N/mm). The femur with the composite plate had 22.7% higher combined average stress compared to the femur with the metal plate, having specific differences of 29.5% (anterior view), 33.9% (posterior view), 1.0% (medial view), and 26.4% (lateral view). The composite plate itself had an average 21.1% reduction in stress compared to the metal plate. The composite plate reduced stress shielding, yet provided adequate stiffness.

  2. Nanoscale Analysis of Interwall Interaction in a Multiwalled Carbon Nanotube by Tip-Enhanced Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

    Chaunchaiyakul, Songpol; Yano, Takeshi; Khoklang, Kamonchanok; Krukowski, Pawel; Akai-Kasaya, Megumi; Saito, Akira; Kuwahara, Yuji

    Raman spectroscopy is a useful tool for the study of carbon materials, but its spatial resolution is limited by the optical diffraction limit. Recently, we constructed a scanning tunneling microscope-based tip-enhanced Raman spectroscopy (STM-TERS) system in ultrahigh vacuum, which overcomes the optical diffraction limit, and enables the investigation of single-molecular Raman spectra simultaneously with topographic imaging. We have investigated position-sensitive Raman spectra along the tube axis of an isolated multiwalled carbon nanotube, which is a result of the different number of nanotube walls at each location. We found that the intensity ratio between the 2D to the G band increases with the number of walls. This indicates that the quantum interference between Raman scattering pathways affects each Raman mode differently. The interaction between nanotube walls induces splitting of the π and π* bands which increases the number of the 2D band scattering pathways owing to double resonance, eventually increasing the probability of scattering for the 2D band relative to the G band. These results provide a deeper understanding of the single-molecule interaction of carbon materials in the nanoscale.

  3. Development of a novel test-setup for identifying the frictional characteristics of carbon fibre reinforced polymer composites at high surface pressure

    NASA Astrophysics Data System (ADS)

    Saxena, Prateek; Schinzel, Marie; Andrich, Manuela; Modler, Niels

    2016-09-01

    Carbon fibre reinforced polymer composites are extensively used in industrial applications. They are light in weight and have excellent load bearing properties. To understand this material's behaviour when carrying loads at high pressure, a tensile-friction test device was developed that can apply a contact surface pressure between composite and counterpart of 50–300 MPa. A tribological investigation of carbon fibre reinforced epoxy composites was carried out, in which the influence of the surface morphology was investigated by using grinding and sandblasting techniques. The friction coefficient of the polymer composite was measured at 100 MPa surface pressure against uncoated and Diamond-Like Carbon coated stainless steel counterparts.

  4. Carbon/Carbon Nanotubes (CNTs) Composites from Green Pellets Contain CNTs and Self-adhesive Carbon Grains from Fibres of Oil Palm Empty Fruit Bunch

    NASA Astrophysics Data System (ADS)

    Deraman, Mohamad; Saad, Siti Khatijah Md.; Ishak, Maria M.; Awitdrus, Taer, Erman; Talib, Ibrahim; Omar, Ramli; Jumali, Mohammad Hafizuddin Hj.

    2010-10-01

    Nano composites green pellets (GPs) were prepared from the mixtures of carbon nanotubes (CNTs) at varying percentage (0, 2, 4, 6, 8 and 10%) and self-adhesive carbon grains (SACG) from fibres of oil palm empty fruit bunch. These GPs were carbonized and CO2 activated to produce activated carbon/CNTs composites in the form of pellets (ACPs). It was found that the density (ρ) and electrical conductivity (σ) of the ACPs varied nonlinearly with CNTs content; as for the CNTs content of 3-5%, we observed the peak values of ρ and σ at 1.3781 gcm-3 and 3.4146 (Ωcm)-1 respectively. The presence of the agglomerated and individual particles of CNTs in the pores of the ACPs was clearly shown by the micrograph of the Field Emission Scanning Electron Microscope (FESEM). The nitrogen adsorption isotherm data showed the decrease in surface area, volume and diameter of pores due to the effect of CNTs. The effect of CNTs on the electrochemical behavior of the ACPs were investigated from the supercapacitor cells fabricated using the ACPs as composite electrodes. It was found that the specific capacitance, energy density and power density of the supercapacitor with electrodes containing 10% CNTs were lower than that with electrodes without CNTs. This result is consistent with the change of pores characteristic due to the presence of CNTs in the ACPs, suggesting the need to optimize the pore characteristic for improving the supercapacitor performance.

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

    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, three-phase boundary for gas-liquid reactions. The performance of the copper electrode is significantly enhanced; at overpotentials between 200 and 400 mV, faradaic efficiencies for carbon dioxide reduction up to 85% are obtained. Moreover, the carbon monoxide formation rate is at least one order of magnitude larger when compared with state-of-the-art nanocrystalline copper electrodes. Copper hollow fibre electrodes can be prepared via a facile method that is compatible with existing large-scale production processes. The results of this study may inspire the development of new types of microtubular electrodes for electrochemical processes in which at least one gas-phase reactant is involved, such as in fuel cell technology.

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

    PubMed Central

    Kas, Recep; Hummadi, Khalid Khazzal; Kortlever, Ruud; de Wit, Patrick; Milbrat, Alexander; Luiten-Olieman, Mieke W. J.; Benes, Nieck E.; 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, three-phase boundary for gas–liquid reactions. The performance of the copper electrode is significantly enhanced; at overpotentials between 200 and 400 mV, faradaic efficiencies for carbon dioxide reduction up to 85% are obtained. Moreover, the carbon monoxide formation rate is at least one order of magnitude larger when compared with state-of-the-art nanocrystalline copper electrodes. Copper hollow fibre electrodes can be prepared via a facile method that is compatible with existing large-scale production processes. The results of this study may inspire the development of new types of microtubular electrodes for electrochemical processes in which at least one gas-phase reactant is involved, such as in fuel cell technology. PMID:26888578

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

    PubMed

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

    2016-02-18

    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, three-phase boundary for gas-liquid reactions. The performance of the copper electrode is significantly enhanced; at overpotentials between 200 and 400 mV, faradaic efficiencies for carbon dioxide reduction up to 85% are obtained. Moreover, the carbon monoxide formation rate is at least one order of magnitude larger when compared with state-of-the-art nanocrystalline copper electrodes. Copper hollow fibre electrodes can be prepared via a facile method that is compatible with existing large-scale production processes. The results of this study may inspire the development of new types of microtubular electrodes for electrochemical processes in which at least one gas-phase reactant is involved, such as in fuel cell technology.

  8. Analysis, design and development of a carbon fibre reinforced plastic knee-ankle-foot orthosis prototype for myopathic patients.

    PubMed

    Granata, C; De Lollis, A; Campo, G; Piancastelli, L; Merlini, L

    1990-01-01

    A traditional knee-ankle-foot orthosis (KAFO) for myopathic patients has been studied for the assessment of loads and fatigue resistance. Starting from this basis a thermoplastic matrix carbon fibre reinforced plastic composite (CFRP) KAFO has been developed in order to reduce the weight. A finite-element simulation programme for deformation analysis was used to compare the behaviour of conventional and CFRP orthosis. There were no breakages either of the prototype or of its parts. The CFRP orthosis allows a weight reduction of more than 40 per cent.

  9. Theoretical investigation of nonlinear resonances in a carbon nanotube cantilever with a tip-mass under electrostatic excitation

    NASA Astrophysics Data System (ADS)

    Kim, I. K.; Lee, S. I.

    2013-09-01

    The nonlinear dynamics of a resonating carbon nanotube (CNT) cantilever having an attached mass at the tip ("tip mass") were investigated by incorporating electrostatic forces and intermolecular interactions between the CNT and a conducting plane surface. This work enables applications of CNT resonating sensors for tiny mass detection and provides a better understanding of the dynamics of CNT cantilevers. The effect of tip mass on a resonating CNT cantilever is normally characterized by the fundamental frequency shift in the linear resonance regime. However, there are more complex dynamics in the nonlinear resonance regime, such as secondary resonances with parametric excitation. The latter have been limited to nano-cantilevers without tip mass or to axially excited micro-beams. To analyze the nonlinear dynamics, we developed a differential equation model that includes both geometric and inertial nonlinear terms for the large vibration amplitudes at increasing drive forces. In our approach, we used Galerkin discretization techniques and numerical integration methods. The CNT cantilever exhibited complex nonlinear responses due to the applied AC and DC voltages and various tip masses. The nonlinear model had a softer response for increasing tip mass than those of the linear model with the same driving conditions. At low applied voltages, the cantilever had linear amplitude and phase responses at primary and secondary superharmonic resonance frequencies. The response branches were softened at the primary resonance through saddle-node (SN) bifurcation from harmonic electrostatic excitation at higher applied voltages. After SN bifurcation, the lower branch of the solution near resonance became unstable. In addition, theoretical analyses were performed on more complex nonlinear responses and stability changes with tip mass variations, such as period-doubling (PD) bifurcation at subharmonic resonance frequencies.

  10. Phase-Imaging with a Sharpened Multi-Walled Carbon Nanotube AFM Tip: Investigation of Low-k Dielectric Polymer Hybrids

    NASA Technical Reports Server (NTRS)

    Nguyen, Cattien V.; Stevens, Ramsey M.; Meyyappan, M.; Volksen, Willi; Miller, Robert D.

    2005-01-01

    Phase shift tapping mode scanning force microscopy (TMSFM) has evolved into a very powerful technique for the nanoscale surface characterization of compositional variations in heterogeneous samples. Phase shift signal measures the difference between the phase angle of the excitation signal and the phase angle of the cantilever response. The signal correlates to the tip-sample inelastic interactions, identifying the different chemical and/or physical property of surfaces. In general, the resolution and quality of scanning probe microscopic images are highly dependent on the size of the scanning probe tip. In improving AFM tip technology, we recently developed a technique for sharpening the tip of a multi-walled carbon nanotube (CNT) AFM tip, reducing the radius of curvature of the CNT tip to less than 5 nm while still maintaining the inherent stability of multi-walled CNT tips. Herein we report the use of sharpened (CNT) AFM tips for phase-imaging of polymer hybrids, a precursor for generating nanoporous low-k dielectrics for on-chip interconnect applications. Using sharpened CNT tips, we obtained phase-contrast images having domains less than 10 nm. In contrast, conventional Si tips and unsharpened CNT tips (radius greater than 15 nm) were not able to resolve the nanoscale domains in the polymer hybrid films. C1early, the size of the CNT tip contributes significantly to the resolution of phase-contrast imaging. In addition, a study on the nonlinear tapping dynamics of the multi-walled CNT tip indicates that the multi-walled CNT tip is immune to conventional imaging instabilities related to the coexistence of attractive and repulsive tapping regimes. This factor may also contribute to the phase-contrast image quality of multi-walled CNT AFM tips. This presentation will also offer data in support of the stability of the CNT tip for phase shift TMSFM.

  11. Experimental and theoretical study of the heating dynamics of carbon-containing optothermal fibre converters for laser surgery

    NASA Astrophysics Data System (ADS)

    Belikov, A. V.; Skrypnik, A. V.; Kurnyshev, V. Yu; Shatilova, K. V.

    2016-06-01

    We have studied carbon-containing optothermal fibre converters (COTFCs) that are located on the distal end of a quartz – quartz optical fibre for delivering laser radiation in medical laser surgery systems and differ in the thickness and structure of the layer of a material converting laser radiation into heat. The heating dynamics of 'thin-film' and '3D' converters have been investigated at average incident 980-nm semiconductor laser beam powers of 0.3, 1.0 and 4.0 W, with the converters placed freely in air. The results demonstrate that, before the instant of disintegration, the efficiency of laser heating of the converter surface can reach 3000 °C W-1 for thin-film converters, 1000 °C W-1 for spherical 3D converters and 55 °C W-1 for planar 3D converters. The thin-film converter breaks down at an average laser beam power as low as 0.30 +/- 0.05 W, which is accompanied by a considerable reduction in heating efficiency and is caused by the disintegration of the carbon film on its surface. The spherical 3D converter breaks down at an average power of 4.0 +/- 0.1 W, as a result of the disintegration of the carbon film on its surface and partial melting of a modified layer containing microbubbles. The carbon film on the surface of the planar 3D converter also disintegrates at an average power of 4.0 +/- 0.1 W, but the structure of the modified layer remains unchanged. We have constructed structural and optophysical models of the converters by simulating light absorption in carbon films on the surface of the COTFC and inside the microbubbles present in the modified layer of the converters. The proposed models of the COTFCs have been shown to adequately describe real converters.

  12. Experimental and theoretical study of the heating dynamics of carbon-containing optothermal fibre converters for laser surgery

    NASA Astrophysics Data System (ADS)

    Belikov, A. V.; Skrypnik, A. V.; Kurnyshev, V. Yu; Shatilova, K. V.

    2016-06-01

    We have studied carbon-containing optothermal fibre converters (COTFCs) that are located on the distal end of a quartz - quartz optical fibre for delivering laser radiation in medical laser surgery systems and differ in the thickness and structure of the layer of a material converting laser radiation into heat. The heating dynamics of 'thin-film' and '3D' converters have been investigated at average incident 980-nm semiconductor laser beam powers of 0.3, 1.0 and 4.0 W, with the converters placed freely in air. The results demonstrate that, before the instant of disintegration, the efficiency of laser heating of the converter surface can reach 3000 °C W-1 for thin-film converters, 1000 °C W-1 for spherical 3D converters and 55 °C W-1 for planar 3D converters. The thin-film converter breaks down at an average laser beam power as low as 0.30 +/- 0.05 W, which is accompanied by a considerable reduction in heating efficiency and is caused by the disintegration of the carbon film on its surface. The spherical 3D converter breaks down at an average power of 4.0 +/- 0.1 W, as a result of the disintegration of the carbon film on its surface and partial melting of a modified layer containing microbubbles. The carbon film on the surface of the planar 3D converter also disintegrates at an average power of 4.0 +/- 0.1 W, but the structure of the modified layer remains unchanged. We have constructed structural and optophysical models of the converters by simulating light absorption in carbon films on the surface of the COTFC and inside the microbubbles present in the modified layer of the converters. The proposed models of the COTFCs have been shown to adequately describe real converters.

  13. Role of negatively charged ions in plasma on the growth and field emission properties of spherical carbon nanotube tip

    SciTech Connect

    Tewari, Aarti; Walia, Ritu; Sharma, Suresh C.

    2012-01-15

    The role of negatively charged ions in plasma on growth (without catalyst) and field emission properties of spherical carbon nanotube (CNT) tip has been theoretically investigated. A theoretical model of charge neutrality, including the kinetics of electrons, negatively and positively charged ions, neutral atoms, and the energy balance of various species has been developed. Numerical calculations of the spherical CNT tip radius for different relative density of negatively charged ions {epsilon}{sub r}(=n{sub SF{sub 6{sup -}}}/n{sub C{sup +}}, where n{sub SF{sub 6{sup -}}} and n{sub C}{sup +} are the equilibrium densities of sulphur hexafluoride and carbon ions, respectively) have been carried out for the typical glow discharge plasma parameters. It is found that the spherical CNT tip radius decreases with {epsilon}{sub r} and hence the field emission of electrons from the spherical CNT tip increases. Some of our theoretical results are in accordance with the existing experimental observations.

  14. Fracture characteristics of carbon fibre, ceramic and non-palladium endodontic post systems at monotonously increasing loads.

    PubMed

    Ottl, P; Hahn, L; Lauer, H Ch; Fay, M

    2002-02-01

    A carbon fibre post system, three non-palladium and one palladium metal post systems, two ceramic post systems, and a metal post system with a ceramic core were studied in vitro. The control group consisted of root-filled test teeth without posts. The test teeth were identical artificial roots of an upper central incisor made from a posterior composite whose module of elasticity was similar to that of natural dentine. All posts were cemented in the roots using Panavia 21 TC. Subsequently, standardized full crowns were cemented onto all roots. On a universal testing machine, the test teeth were loaded palatally at monotonously increasing loads until root fracture. The highest mean fracture loads were found for the carbon fibre post system (312.5 +/- 58.8 N). The fracture load of non-palladium metal posts (242.3-300.4 N) did not differ significantly from that of the Perma-dor post (265.9 N), which does contain palladium. Values of 300.3 +/- 89.3 N (aluminium oxide ceramics) and 193.5 +/-57.0 N (zirconia ceramics) were found for the ceramic posts. The control group exhibited a fracture load of 228.8 +/- 35.7 N. The mean distance between the vestibular end of the fracture gap and the point of force application was between 10.1 +/- 2.3 and 14.7 +/- 1.2 mm.

  15. Acoustic Emission Source Location in Unidirectional Carbon-Fibre-Reinforced Plastic Plates Using Virtually Trained Artificial Neural Networks

    SciTech Connect

    Caprino, G.; Lopresto, V.; Leone, C.; Papa, I.

    2010-06-02

    Acoustic emission source location in a unidirectional carbon-fibre-reinforced plastic plate was attempted employing Artificial Neural Network (ANN) technology. The acoustic emission events were produced by a lead break, and the response wave received by piezoelectric sensors, type VS150-M resonant at 150 kHz. The waves were detected by a Vallen AMSY4 eight-channel instrumentation. The time of arrival, determined through the conventional threshold crossing technique, was used to measure the dependence of wave velocity on fibre orientation. A simple empirical formula, relying on classical lamination and suggested by wave propagation theory, was able to accurately model the experimental trend. Based on the formula, virtual training and testing data sets were generated for the case of a plate monitored by three transducers, and adopted to select two potentially effective ANN architectures. For final validation, experimental tests were carried out, positioning the source at predetermined points evenly distributed within the plate area. A very satisfactory correlation was found between the actual source locations and the ANN predictions.

  16. Acoustic Emission Source Location in Unidirectional Carbon-Fibre-Reinforced Plastic Plates Using Virtually Trained Artificial Neural Networks

    NASA Astrophysics Data System (ADS)

    Caprino, G.; Lopresto, V.; Leone, C.; Papa, I.

    2010-06-01

    Acoustic emission source location in a unidirectional carbon-fibre-reinforced plastic plate was attempted employing Artificial Neural Network (ANN) technology. The acoustic emission events were produced by a lead break, and the response wave received by piezoelectric sensors, type VS150-M resonant at 150 kHz. The waves were detected by a Vallen AMSY4 eight-channel instrumentation. The time of arrival, determined through the conventional threshold crossing technique, was used to measure the dependence of wave velocity on fibre orientation. A simple empirical formula, relying on classical lamination and suggested by wave propagation theory, was able to accurately model the experimental trend. Based on the formula, virtual training and testing data sets were generated for the case of a plate monitored by three transducers, and adopted to select two potentially effective ANN architectures. For final validation, experimental tests were carried out, positioning the source at predetermined points evenly distributed within the plate area. A very satisfactory correlation was found between the actual source locations and the ANN predictions.

  17. Effect of UV and electrochemical surface treatments on the adsorption and reaction of linear alcohols on non-porous carbon fibre

    NASA Astrophysics Data System (ADS)

    Osbeck, S.; Ward, S.; Idriss, H.

    2013-04-01

    The adsorption properties of untreated, electrochemically treated and ultra-violet/ozone treated polyacrylonitrile based carbon fibres were investigated using temperature programmed desorption (TPD) on a series of linear alcohols as probes in order to understand its surface properties. Surface uptake was found to be sensitive to both the surface treatment and the nature of the adsorbates. Surface coverage increased with increasing alcohol chain due to the increase in their polarizability. It also increased with the level of surface oxygen of the fibres most likely because it facilitates the Osbnd H bond dissociation of the alcohol functional group. In addition, the desorption temperature (during TPD) tracked the surface oxygen levels (as determined from XPS O1s signal) suggesting increasing in the adsorption energy. The reactions of C1-C4 linear alcohols were also investigated on the surface of the fibre carbon. The main reaction was dehydrogenation to the corresponding aldehydes; the dehydration reaction to olefins was not observed. The dehydrogenation reaction was sensitive to the length of the alky chain. It was highest for methanol (to formaldehyde) and decreased with increasing the carbon number. Overall TPD of linear alcohols was shown to be a promising method for quantifying the level and strength of bonding occurring on carbon fibre surfaces.

  18. Selective functionalization of carbon nanotube tips allowing fabrication of new classes of nanoscale sensing and manipulation tools

    NASA Technical Reports Server (NTRS)

    Wade, Lawrence A. (Inventor); Shapiro, Ian R. (Inventor); Collier, Charles Patrick (Inventor); Esplandiu, Maria J. (Inventor); Bittner, Jr., Vern Garrett (Inventor); Giapis, Konstantinos P. (Inventor)

    2009-01-01

    Embodiments in accordance with the present invention relate to techniques for the growth and attachment of single wall carbon nanotubes (SWNT), facilitating their use as robust and well-characterized tools for AFM imaging and other applications. In accordance with one embodiment, SWNTs attached to an AFM tip can function as a structural scaffold for nanoscale device fabrication on a scanning probe. Such a probe can trigger, with nanometer precision, specific biochemical reactions or conformational changes in biological systems. The consequences of such triggering can be observed in real time by single-molecule fluorescence, electrical, and/or AFM sensing. Specific embodiments in accordance with the present invention utilize sensing and manipulation of individual molecules with carbon nanotubes, coupled with single-molecule fluorescence imaging, to allow observation of spectroscopic signals in response to mechanically induced molecular changes. Biological macromolecules such as proteins or DNA can be attached to nanotubes to create highly specific single-molecule probes for investigations of intermolecular dynamics, for assembling hybrid biological and nanoscale materials, or for developing molecular electronics. In one example, electrical wiring of single redox enzymes to carbon nanotube scanning probes allows observation and electrochemical control over single enzymatic reactions by monitoring fluorescence from a redox-active cofactor or the formation of fluorescent products. Enzymes ''nanowired'' to the tips of carbon nanotubes in accordance with embodiments of the present invention, may enable extremely sensitive probing of biological stimulus-response with high spatial resolution, including product-induced signal transduction.

  19. Effect of doping on growth and field emission properties of spherical carbon nanotube tip placed over cylindrical surface

    NASA Astrophysics Data System (ADS)

    Santolia, Isha; Tewari, Aarti; Sharma, Suresh C.; Sharma, Rinku

    2014-06-01

    Theoretical investigations to study the effect of doping of hetero-atoms on the growth and field emission properties of Carbon Nanotubes (CNTs) tip placed over a cylindrical surface in complex plasma have been carried out. A theoretical model incorporating kinetics of plasma species such as electron, ions, and neutral atoms including doping elements like nitrogen (N) and boron (B) and energy balance of CNTs in a complex plasma has been developed. The effect of doping elements of N and B on the growth of CNTs, namely, the tip radius has been carried out for typical glow discharge plasma parameters. It is found that N and B as doping elements affect the radius of CNTs extensively. We obtain small radii of CNT doped with N and large radius of CNT doped with B. The field emission characteristics from CNTs have therefore been suggested on the basis of results obtained. Some of theoretical results are in compliance with the existing experimental observations.

  20. Effect of doping on growth and field emission properties of spherical carbon nanotube tip placed over cylindrical surface

    SciTech Connect

    Santolia, Isha; Tewari, Aarti; Sharma, Suresh C.; Sharma, Rinku

    2014-06-15

    Theoretical investigations to study the effect of doping of hetero-atoms on the growth and field emission properties of Carbon Nanotubes (CNTs) tip placed over a cylindrical surface in complex plasma have been carried out. A theoretical model incorporating kinetics of plasma species such as electron, ions, and neutral atoms including doping elements like nitrogen (N) and boron (B) and energy balance of CNTs in a complex plasma has been developed. The effect of doping elements of N and B on the growth of CNTs, namely, the tip radius has been carried out for typical glow discharge plasma parameters. It is found that N and B as doping elements affect the radius of CNTs extensively. We obtain small radii of CNT doped with N and large radius of CNT doped with B. The field emission characteristics from CNTs have therefore been suggested on the basis of results obtained. Some of theoretical results are in compliance with the existing experimental observations.

  1. High throughput nanofabrication of silicon nanowire and carbon nanotube tips on AFM probes by stencil-deposited catalysts.

    PubMed

    Engstrom, Daniel S; Savu, Veronica; Zhu, Xueni; Bu, Ian Y Y; Milne, William I; Brugger, Juergen; Boggild, Peter

    2011-04-13

    A new and versatile technique for the wafer scale nanofabrication of silicon nanowire (SiNW) and multiwalled carbon nanotube (MWNT) tips on atomic force microscope (AFM) probes is presented. Catalyst material for the SiNW and MWNT growth was deposited on prefabricated AFM probes using aligned wafer scale nanostencil lithography. Individual vertical SiNWs were grown epitaxially by a catalytic vapor-liquid-solid (VLS) process and MWNTs were grown by a plasma-enhanced chemical vapor (PECVD) process on the AFM probes. The AFM probes were tested for imaging micrometers-deep trenches, where they demonstrated a significantly better performance than commercial high aspect ratio tips. Our method demonstrates a reliable and cost-efficient route toward wafer scale manufacturing of SiNW and MWNT AFM probes. PMID:21446752

  2. Laser treatment of carbon fibre reinforced thermoplastic matrix for adhesive bonding

    NASA Astrophysics Data System (ADS)

    Genna, S.; Leone, C.; Ucciardello, N.; Giuliani, M.

    2016-05-01

    In the present study, laser surface treatment of CFRP made of PPS thermoplastic matrix by means of a 30 W Q-Switched Yb:YAG fiber laser, is investigated with the aim to improve adhesive bonding. The process parameters pulse power, scanning speed, hatch distance and scanning strategy, were varied to the aim to study the influence of the process condition on the first top resin layer removal and fibre damage. The operating window was experimentally determined. The effectiveness of laser treatment was verified by single lap shear test.

  3. Hydrofluoric-nitric-sulphuric-acid surface treatment of tungsten for carbon fibre-reinforced composite hybrids in space applications

    NASA Astrophysics Data System (ADS)

    Kanerva, M.; Johansson, L.-S.; Campbell, J. M.; Revitzer, H.; Sarlin, E.; Brander, T.; Saarela, O.

    2015-02-01

    Hybrid material systems, such as combinations of tungsten foils and carbon fibre-reinforced plastic (CFRP), are replacing metal alloy concepts in spacecraft enclosures. However, a good adhesion between the tungsten oxide scale and the epoxy resin used is required. Here, the effects of a hydrofluoric-nitric-sulphuric-acid (HFNS) treatment on tungsten oxides and subsequent adhesion to CFRP are analysed using atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and fracture testing. The work shows that HFNS treatment results in decreased oxygen content, over 50% thinner tungsten trioxide (WO3) layer and increased nano-roughness on thin tungsten foils. Fracture testing established a 39% increase in the average critical strain for tungsten-CFRP specimens after HFNS treatment was carried out on tungsten. The effect of the oxide scale modification regarding the critical strain energy release rate was ΔGc≈ 8.4 J/m2.

  4. Reactor irradiation effects on the ultimate tensile and the interlaminar shear strength of carbon fibre reinforced epoxies at 77 K

    NASA Astrophysics Data System (ADS)

    Spießberger, S. M.; Humer, K.; Tschegg, E. K.; Weber, H. W.; Gerstenberg, H.

    A carbon fibre reinforced plastics material (CFRP) `TORAYCA T300 3K', which was developed for various applications, including cryogenics, was irradiated at 5 K and 340 K with different reactor spectra up to a fast neutron fluence of 5×10 22 m -2 ( E>0.1 MeV). All investigations in the interlaminar shear mode as well as the tensile tests were made at 77 K, the samples subjected to 5 K irradiation were measured before and after an annealing cycle (of about one day) to room temperature. Fractographic examinations of the tensile samples were used to examine the complicated fracture process. Both the interlaminar shear strength and the ultimate tensile strength show good radiation resistance at the lowest total absorbed dose (˜5×10 6 Gy), but fail at higher dose levels (˜10 8 Gy).

  5. Corrosive effect of carbon-fibre reinforced plastic on stainless-steel screws during implantation into man.

    PubMed

    Tayton, K

    1983-01-01

    The corrosion of stainless-steel screws used to fix carbon-fibre reinforced plastic (CFRP) plates to human fractures was compared with the corrosion on similar screws used to fix stainless-steel AO plates. Corrosive changes were noted in both sets of screws with similar frequency and severity; however, the stainless-steel plates were 'in situ' almost twice as long as the CFRP ones, showing that the corrosive changes occurred more rapidly on screws in contact with CFRP. Nevertheless, over the implantation time necessary for bone healing, corrosion was very mild and there is no clinical contra-indication to the use of stainless-steel and CFRP together in this particular application.

  6. Investigating the use of endogenous quinoid moieties on carbon fibre as means of developing micro pH sensors.

    PubMed

    Anderson, Ashleigh; Phair, Jolene; Benson, John; Meenan, Brian; Davis, James

    2014-10-01

    The redox profile obtained from electrochemically oxidised carbon fibre was exploited as a foundation from which to design a reusable pH probe. X-ray photoelectron spectroscopy of the surface after anodisation revealed an increase in the population of endogenous quinone moieties. Square wave voltammograms recorded in various buffer solutions (pH3-9) yielded a distinct and unambiguous oxidation process through which to ascribe the peak potential - with the latter found to shift in a sub-Nernstian (-0.052 V/pH) manner. The design of a discrete 2-electrode reusable probe which provides a rapid assessment of pH is described and a preliminary characterisation of the electrochemical performance is critically assessed.

  7. A preliminary biomechanical study of a novel carbon-fibre hip implant versus standard metallic hip implants.

    PubMed

    Bougherara, Habiba; Zdero, Rad; Dubov, Anton; Shah, Suraj; Khurshid, Shaheen; Schemitsch, Emil H

    2011-01-01

    Total hip arthroplasty is a widespread surgical approach for treating severe osteoarthritis of the human hip. Aseptic loosening of standard metallic hip implants due to stress shielding and bone loss has motivated the development of new materials for hip prostheses. Numerically, a three-dimensional finite element (FE) model that mimicked hip implants was used to compare a new hip stem to two commercially available implants. The hip implants simulated were a novel CF/PA12 carbon-fibre polyamide-based composite hip stem, the Exeter hip stem (Stryker, Mahwah, NJ, USA), and the Omnifit Eon (Stryker, Mahwah, NJ, USA). A virtual axial load of 3 kN was applied to the FE model. Strain and stress distributions were computed. Experimentally, the three hip stems had their distal portions rigidly mounted and had strain gauges placed along the surface at 3 medial and 3 lateral locations. Axial loads of 3 kN were applied. Measurements of axial stiffness and strain were taken and compared to FE analysis. The overall linear correlation between FE model versus experimental strains showed reasonable results for the lines-of-best-fit for the Composite (Pearson R(2)=0.69, slope=0.82), Exeter (Pearson R(2)=0.78, slope=0.59), and Omnifit (Pearson R(2)=0.66, slope=0.45), with some divergence for the most distal strain locations. From FE analysis, the von Mises stress range for the Composite stem was much lower than that in the Omnifit and Exeter implants by 200% and 45%, respectively. The preliminary experiments showed that the Composite stem stiffness (1982 N/mm) was lower than the metallic hip stem stiffnesses (Exeter, 2460 N/mm; Omnifit, 2543 N/mm). This is the first assessment of stress, strain, and stiffness of the CF/PA12 carbon-fibre hip stem compared to standard commercially-available devices.

  8. Characterization and analysis of carbon fibre-reinforced polymer composite laminates with embedded circular vasculature

    PubMed Central

    Huang, C.-Y.; Trask, R. S.; Bond, I. P.

    2010-01-01

    A study of the influence of embedded circular hollow vascules on structural performance of a fibre-reinforced polymer (FRP) composite laminate is presented. Incorporating such vascules will lead to multi-functional composites by bestowing functions such as self-healing and active thermal management. However, the presence of off-axis vascules leads to localized disruption to the fibre architecture, i.e. resin-rich pockets, which are regarded as internal defects and may cause stress concentrations within the structure. Engineering approaches for creating these simple vascule geometries in conventional FRP laminates are proposed and demonstrated. This study includes development of a manufacturing method for forming vascules, microscopic characterization of their effect on the laminate, finite element (FE) analysis of crack initiation and failure under load, and validation of the FE results via mechanical testing observed using high-speed photography. The failure behaviour predicted by FE modelling is in good agreement with experimental results. The reduction in compressive strength owing to the embedding of circular vascules ranges from 13 to 70 per cent, which correlates with vascule dimension. PMID:20150337

  9. Characterization and analysis of carbon fibre-reinforced polymer composite laminates with embedded circular vasculature.

    PubMed

    Huang, C-Y; Trask, R S; Bond, I P

    2010-08-01

    A study of the influence of embedded circular hollow vascules on structural performance of a fibre-reinforced polymer (FRP) composite laminate is presented. Incorporating such vascules will lead to multi-functional composites by bestowing functions such as self-healing and active thermal management. However, the presence of off-axis vascules leads to localized disruption to the fibre architecture, i.e. resin-rich pockets, which are regarded as internal defects and may cause stress concentrations within the structure. Engineering approaches for creating these simple vascule geometries in conventional FRP laminates are proposed and demonstrated. This study includes development of a manufacturing method for forming vascules, microscopic characterization of their effect on the laminate, finite element (FE) analysis of crack initiation and failure under load, and validation of the FE results via mechanical testing observed using high-speed photography. The failure behaviour predicted by FE modelling is in good agreement with experimental results. The reduction in compressive strength owing to the embedding of circular vascules ranges from 13 to 70 per cent, which correlates with vascule dimension.

  10. Carbon Nanotube Tip Probes: Stability and Lateral Resolution in Scanning Probe Microscopy and Application to Surface Science to Semiconductors

    NASA Technical Reports Server (NTRS)

    Nguyen, Cattien V.; Chao, Kuo-Jen; Stevens, Ramsey M. D.; Delzeit, Lance; Cassell, Alan; Han, Jie; Meyyappan, M.; Arnold, James (Technical Monitor)

    2001-01-01

    In this paper we present results on the stability and lateral resolution capability of carbon nanotube (CNT) scanning probes as applied to atomic force microscopy (AFM). Surface topography images of ultra-thin films (2-5 nm thickness) obtained with AFM are used to illustrate the lateral resolution capability of single-walled carbon nanotube probes. Images of metal films prepared by ion beam sputtering exhibit grain sizes ranging from greater than 10 nm to as small as approximately 2 nm for gold and iridium respectively. In addition, imaging stability and lifetime of multi-walled carbon nanotube scanning probes are studied on a relatively hard surface of silicon nitride (Si3N4). AFM images Of Si3N4 surface collected after more than 15 hrs of continuous scanning show no detectable degradation in lateral resolution. These results indicate the general feasibility of CNT tips and scanning probe microscopy for examining nanometer-scale surface features of deposited metals as well as non-conductive thin films. AFM coupled with CNT tips offers a simple and nondestructive technique for probing a variety of surfaces, and has immense potential as a surface characterization tool in integrated circuit manufacturing.

  11. Fibre laser machining for glassy carbon master mould and soft lithography based two-step printing for Ag nanoparticle structures

    NASA Astrophysics Data System (ADS)

    Hu, Qin; Chopra, Pranav

    2011-04-01

    Traditional manufacturing techniques widely used in semiconductor industries involve many processing steps that consume both time and material and lead to high cost. Soft Lithography (SL) offers a new way to print micro/nano structures, which is a fast and low cost alternative to the conventional route, although the high processing temperature of metals, semiconductors and ceramics limits the application SL techniques. In this paper we report the use of Ag nanoparticles as building blocks to make structures by combing the merits of SL, nanotechnology and laser engineering, which provide a simple additive route with low capital investment. Glassy carbon (GC) was chosen as the material for the rigid master mould, as no release coating is needed for replicating the polydimethylsiloxane (PDMS) mould. GC moulds were machined by a nanosecond-pulsed Yb fibre laser. The machined GC moulds were further cleaned by PDMS and the same fibre laser system to remove the process debris. The master mould was further replicated by PDMS. PDMS replicas with either positive or negative features from the master mould were attainable. A two-step strategy was used to print patterns using PDMS mould and Ag nanoparticle paste. Metal patterns were formed on various substrates, and the PDMS mould was left clean and ready for reuse. The resultant printed patterns were found to be uniform over millimetre range, with negligible residual layer, and the thickness of up to several micrometres. The thermal responses of Ag nanoparticles at various sintering temperatures were investigated. The factors affecting the resolution of printed structures were discussed.

  12. Preparation of highly porous binderless activated carbon electrodes from fibres of oil palm empty fruit bunches for application in supercapacitors.

    PubMed

    Farma, R; Deraman, M; Awitdrus, A; Talib, I A; Taer, E; Basri, N H; Manjunatha, J G; Ishak, M M; Dollah, B N M; Hashmi, S A

    2013-03-01

    Fibres from oil palm empty fruit bunches, generated in large quantities by palm oil mills, were processed into self-adhesive carbon grains (SACG). Untreated and KOH-treated SACG were converted without binder into green monolith prior to N2-carbonisation and CO2-activation to produce highly porous binderless carbon monolith electrodes for supercapacitor applications. Characterisation of the pore structure of the electrodes revealed a significant advantage from combining the chemical and physical activation processes. The electrochemical measurements of the supercapacitor cells fabricated using these electrodes, using cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge-discharge techniques consistently found that approximately 3h of activation time, achieved via a multi-step heating profile, produced electrodes with a high surface area of 1704m(2)g(-1) and a total pore volume of 0.889cm(3)g(-1), corresponding to high values for the specific capacitance, specific energy and specific power of 150Fg(-1), 4.297Whkg(-1) and 173Wkg(-1), respectively.

  13. Biomechanical properties of a structurally optimized carbon-fibre/epoxy intramedullary nail for femoral shaft fracture fixation.

    PubMed

    Samiezadeh, Saeid; Fawaz, Zouheir; Bougherara, Habiba

    2016-03-01

    Intramedullary nails are the golden treatment option for diaphyseal fractures. However, their high stiffness can shield the surrounding bone from the natural physiologic load resulting in subsequent bone loss. Their stiff structure can also delay union by reducing compressive loads at the fracture site, thereby inhibiting secondary bone healing. Composite intramedullary nails have recently been introduced to address these drawbacks. The purpose of this study is to evaluate the mechanical properties of a previously developed composite IM nail made of carbon-fibre/epoxy whose structure was optimized based on fracture healing requirements using the selective stress shielding approach. Following manufacturing, the cross-section of the composite nail was examined under an optical microscope to find the porosity of the structure. Mechanical properties of the proposed composite intramedullary nail were determined using standard tension, compression, bending, and torsion tests. The failed specimens were then examined to obtain the modes of failure. The material showed high strength in tension (403.9±7.8MPa), compression (316.9±10.9MPa), bending (405.3±8.1MPa), and torsion (328.5±7.3MPa). Comparing the flexural modulus (41.1±0.9GPa) with the compressive modulus (10.0±0.2GPa) yielded that the material was significantly more flexible in compression than in bending. This customized flexibility along with the high torsional stiffness of the nail (70.7±2.0Nm(2)) has made it ideal as a fracture fixation device since this unique structure can stabilize the fracture while allowing for compression of fracture ends. Negligible moisture absorption (~0.5%) and low porosity of the laminate structure (< 3%) are other advantages of the proposed structure. The findings suggested that the carbon-fibre/epoxy intramedullary nail is flexible axially while being relatively rigid in bending and torsion and is strong enough in all types of physiologic loading, making it a potential

  14. Biomechanical properties of a structurally optimized carbon-fibre/epoxy intramedullary nail for femoral shaft fracture fixation.

    PubMed

    Samiezadeh, Saeid; Fawaz, Zouheir; Bougherara, Habiba

    2016-03-01

    Intramedullary nails are the golden treatment option for diaphyseal fractures. However, their high stiffness can shield the surrounding bone from the natural physiologic load resulting in subsequent bone loss. Their stiff structure can also delay union by reducing compressive loads at the fracture site, thereby inhibiting secondary bone healing. Composite intramedullary nails have recently been introduced to address these drawbacks. The purpose of this study is to evaluate the mechanical properties of a previously developed composite IM nail made of carbon-fibre/epoxy whose structure was optimized based on fracture healing requirements using the selective stress shielding approach. Following manufacturing, the cross-section of the composite nail was examined under an optical microscope to find the porosity of the structure. Mechanical properties of the proposed composite intramedullary nail were determined using standard tension, compression, bending, and torsion tests. The failed specimens were then examined to obtain the modes of failure. The material showed high strength in tension (403.9±7.8MPa), compression (316.9±10.9MPa), bending (405.3±8.1MPa), and torsion (328.5±7.3MPa). Comparing the flexural modulus (41.1±0.9GPa) with the compressive modulus (10.0±0.2GPa) yielded that the material was significantly more flexible in compression than in bending. This customized flexibility along with the high torsional stiffness of the nail (70.7±2.0Nm(2)) has made it ideal as a fracture fixation device since this unique structure can stabilize the fracture while allowing for compression of fracture ends. Negligible moisture absorption (~0.5%) and low porosity of the laminate structure (< 3%) are other advantages of the proposed structure. The findings suggested that the carbon-fibre/epoxy intramedullary nail is flexible axially while being relatively rigid in bending and torsion and is strong enough in all types of physiologic loading, making it a potential

  15. The influence of nominal stress on wear factors of carbon fibre-reinforced polyetheretherketone (PEEK-OPTIMA® Wear Performance) against zirconia toughened alumina (Biolox® delta ceramic).

    PubMed

    Evans, Andrew; Horton, Henrietta; Unsworth, Anthony; Briscoe, Adam

    2014-06-01

    Carbon fibre-reinforced polyetheretherketone is an attractive alternative to ultra-high-molecular-weight polyethylene in artificial joints, but little has been published on the influence of stress on the wear factor. We know that in ultra-high-molecular-weight polyethylene, the wear factor reduces as the normal stress increases, which is counter-intuitive but very helpful in the case of non-conforming contacts. In this study, carbon fibre-reinforced polyetheretherketone (PEEK-OPTIMA(®) Wear Performance) has been investigated in a pin-on-plate machine under steady loads and under stresses typical of hip and knee joints. At stresses below about 6 MPa, wear factors are between 10 and a 100 times lower than for ultra-high-molecular-weight polyethylene but at higher stresses the wear factors increase substantially.

  16. Simultaneous Determination of Parathion, Malathion, Diazinon, and Pirimiphos Methyl in Dried Medicinal Plants Using Solid-Phase Microextraction Fibre Coated with Single-Walled Carbon Nanotubes

    PubMed Central

    Ahmadkhaniha, Reza; Samadi, Nasrin; Salimi, Mona; Sarkhail, Parisa; Rastkari, Noushin

    2012-01-01

    A reliable and sensitive headspace solid-phase microextraction gas chromatography-mass spectrometry method for simultaneous determination of different organophosphorus pesticides in dried medicinal plant samples is described. The analytes were extracted by single-walled carbon nanotubes as a new solid-phase microextraction adsorbent. The developed method showed good performance. For diazinon and pirimiphos methyl calibration, curves were linear (r2 ≥ 0.993) over the concentration ranges from 1.5 to 300 ng g−1, and the limit of detection at signal-to-noise ratio of 3 was 0.3 ng g−1. For parathion and malathion, the linear range and limit of detection were 2.5–300 (r2 ≥ 0.991) and 0.5 ng g−1, respectively. In addition, a comparative study between the single-walled carbon nanotubes and a commercial polydimethylsiloxane fibre for the determination of target analytes was carried out. Single-walled carbon nanotubes fibre showed higher extraction capacity, better thermal stability (over 350°C), and longer lifespan (over 250 times) than the commercial polydimethylsiloxane fibre. The developed method was successfully applied to determine target organophosphorus pesticides in real samples. PMID:22645439

  17. Simultaneous determination of parathion, malathion, diazinon, and pirimiphos methyl in dried medicinal plants using solid-phase microextraction fibre coated with single-walled carbon nanotubes.

    PubMed

    Ahmadkhaniha, Reza; Samadi, Nasrin; Salimi, Mona; Sarkhail, Parisa; Rastkari, Noushin

    2012-01-01

    A reliable and sensitive headspace solid-phase microextraction gas chromatography-mass spectrometry method for simultaneous determination of different organophosphorus pesticides in dried medicinal plant samples is described. The analytes were extracted by single-walled carbon nanotubes as a new solid-phase microextraction adsorbent. The developed method showed good performance. For diazinon and pirimiphos methyl calibration, curves were linear (r(2) ≥ 0.993) over the concentration ranges from 1.5 to 300 ng g(-1), and the limit of detection at signal-to-noise ratio of 3 was 0.3 ng g(-1). For parathion and malathion, the linear range and limit of detection were 2.5-300 (r(2) ≥ 0.991) and 0.5 ng g(-1), respectively. In addition, a comparative study between the single-walled carbon nanotubes and a commercial polydimethylsiloxane fibre for the determination of target analytes was carried out. Single-walled carbon nanotubes fibre showed higher extraction capacity, better thermal stability (over 350 °C), and longer lifespan (over 250 times) than the commercial polydimethylsiloxane fibre. The developed method was successfully applied to determine target organophosphorus pesticides in real samples.

  18. Sewage sludge pretreatment by microwave irradiation combined with activated carbon fibre at alkaline pH for anaerobic digestion.

    PubMed

    Sun, Dedong; Guo, Sixiao; Ma, Nina; Wang, Guowen; Ma, Chun; Hao, Jun; Xue, Mang; Zhang, Xinxin

    2016-01-01

    This research focuses on the effects of microwave-assisted activated carbon fibre (ACF) (MW-ACF) treatment on sewage sludge at alkaline pH. The disintegration and biodegradability of sewage sludge were studied. It was found that the MW-ACF process at alkaline pH provided a rapid and efficient process to disrupt the microbial cells in the sludge. The results suggested that when irradiated at 800 W MW for 110 s with a dose of 1.0 g ACF/g solid concentration (SS) at pH 10.5, the MW-ACF pretreatment achieved 55% SS disintegration, 23% greater than the value of MW alone (32%). The concentration of total nitrogen, total phosphorus, supernatant soluble chemical oxygen demand, protein, and polysaccharide increased by 60%, 144%, 145%, 74%, and 77%, respectively. An increase in biogas production by 63.7% was achieved after 20 days of anaerobic digestion (AD), compared to the control. The results indicated that the MW-ACF pretreatment process at alkaline pH provides novel sludge management options in disintegration of sewage sludge for further AD.

  19. Contrast Enhancement of MicroCT Scans to Aid 3D Modelling of Carbon Fibre Fabric Composites

    NASA Astrophysics Data System (ADS)

    Djukic, Luke P.; Pearce, Garth M.; Herszberg, Israel; Bannister, Michael K.; Mollenhauer, David H.

    2013-12-01

    This paper presents a methodology for volume capture and rendering of plain weave and multi-layer fabric meso-architectures within a consolidated, cured laminate. Micro X-ray Computed Tomography (MicroCT) is an excellent tool for the non-destructive visualisation of material microstructures however the contrast between tows and resin is poor for carbon fibre composites. Firstly, this paper demonstrates techniques to improve the contrast of the microCT images by introducing higher density materials such as gold, iodine and glass into the fabric. Two approaches were demonstrated to be effective for enhancing the differentiation between the tows in the reconstructed microCT visualisations. Secondly, a method of generating three-dimensional volume models of woven composites using microCT scan data is discussed. The process of generating a model is explained from initial manufacture with the aid of an example plain weave fabric. These methods are to be used in the finite element modelling of three-dimensional fabric preforms in future work.

  20. The effect of serrations on carbon fibre posts-retention within the root canal, core retention, and post rigidity.

    PubMed

    Love, R M; Purton, D G

    1996-01-01

    The retention in root canals of serrated carbon fibre Composiposts and stainless steel Paraposts was tested under tensile load. Twenty unrestored human roots were endodontically prepared and root filled. Two groups of 10 roots received 1.4-mm Composiposts or 1.25-mm Paraposts luted with a resin cement. The specimens were then embedded in acrylic resin and mounted in an Instron machine. The tensile force (kg) required to dislodge the posts was recorded and analysed with Student's test. The results revealed that there was no significant difference in the retention of either post (P > .05). The rigidty of 10 1.4-mm serrated Composiposts was tested in a three-point bend test in an Instron machine, and the retention of composite cores to 10 of these posts under tensile force was also tested. The results from these tests were compared to previous data from the authors' laboratory and revealed that the serrations significantly reduced the rigidity of the post (P < .001) and increased the retention of a core material (P < .001). PMID:9108751

  1. Reliability of stable carbon and oxygen isotope compositions of pedogenic needle fibre calcite as environmental indicators: examples from Western Europe.

    PubMed

    Millière, Laure; Spangenberg, Jorge E; Bindschedler, Saskia; Cailleau, Guillaume; Verrecchia, Eric P

    2011-09-01

    Stable carbon and oxygen isotope analyses were conducted on pedogenic needle fibre calcite (NFC) from seven sites in areas with roughly similar temperate climates in Western Europe, including the Swiss Jura Mountains, eastern and southern France, northern Wales, and north-eastern Spain. The δ(13)C values (-12.5 to-6.8 ‰ Vienna Pee Dee Belemnite (VPDB)) record the predominant C(3) vegetation cover at the sites. A good correlation was found between mean monthly climatic parameters (air temperature, number of frost days, humidity, and precipitation) and δ(18)O values (-7.8 to-3.4‰ VPDB) of all the NFC. Similar seasonal variations of δ(18)O values for monthly NFC samples from the Swiss sites and those of mean monthly δ(18)O values of local precipitation and meteorological data point out precipitation and preferential growth/or recrystallisation of the pedogenic needle calcite during dry seasons. These covariations indicate the potential of stable isotope compositions of preserved NFC in fossil soil horizons as a promising tool for palaeoenvironmental reconstructions.

  2. Investigation of metallic and carbon fibre PEEK fracture fixation devices for three-part proximal humeral fractures.

    PubMed

    Feerick, Emer M; Kennedy, Jim; Mullett, Hannan; FitzPatrick, David; McGarry, Patrick

    2013-06-01

    A computational investigation of proximal humeral fracture fixation has been conducted. Four devices were selected for the study; a locking plate, intramedullary nail (IM Nail), K-wires and a Bilboquet device. A 3D model of a humerus was created using a process of thresholding based on the grayscale values of a CT scan of an intact humerus. An idealised three part fracture was created in addition to removing a standard volume from the humeral head as a representation of bone voids that occur as a result of the injury. All finite element simulations conducted represent 90° arm abduction. Simulations were conducted to investigate the effect of filling this bone void with calcium phosphate cement for each device. The effect of constructing devices from carbon fibre polyetheretherketone (CFPEEK) was investigated. Simulations of cement reinforced devices predict greater stability for each device. The average unreinforced fracture line opening (FLO) is reduced by 48.5% for metallic devices with a lesser effect on composite devices with FLO reduced by 23.6%. Relative sliding (shear displacement) is also reduced between fracture fragments by an average of 58.34%. CFPEEK device simulations predict reduced stresses at the device-bone interface.

  3. Reduced stress shielding with limited micromotions using a carbon fibre composite biomimetic hip stem: a finite element model.

    PubMed

    Caouette, C; Yahia, L H; Bureau, M N

    2011-09-01

    Total hip arthroplasty (THA) enjoys excellent rates of success in older patients, but younger patients are still at risk of aseptic loosening and bone resorption from stress shielding. One solution to the stress shielding problem is to use a hip stem with mechanical properties matching those of cortical bone. The objective of the present study was to investigate numerically the biomechanical performance of such a biomimetic hip stem based on a hydroxyapatite (HA)-coated carbon fibre composite. A finite element model (FEM) of the biomimetic stem was constructed. Contact elements were studied to model the bone-implant interface in a non-osseointegrated and osseointegrated state in the best way. Three static load cases representing slow walking, stair climbing, and gait in a healthy individual were considered. Stress shielding and bone-implant interface micromotions were evaluated and compared with the results of a similar FEM based on titanium alloy (Ti-6Al-4V). The composite stems allowed for reduced stress shielding when compared with a traditional Ti-6Al-4V stem. Micromotions were slightly higher with the composite stem, but remained below 40 microm on most of the HA-coated surface. It is concluded that a biomimetic composite stem might offer a better compromise between stress shielding and micromotions than the Ti-6Al-4V stem with the same external geometry.

  4. Sewage sludge pretreatment by microwave irradiation combined with activated carbon fibre at alkaline pH for anaerobic digestion.

    PubMed

    Sun, Dedong; Guo, Sixiao; Ma, Nina; Wang, Guowen; Ma, Chun; Hao, Jun; Xue, Mang; Zhang, Xinxin

    2016-01-01

    This research focuses on the effects of microwave-assisted activated carbon fibre (ACF) (MW-ACF) treatment on sewage sludge at alkaline pH. The disintegration and biodegradability of sewage sludge were studied. It was found that the MW-ACF process at alkaline pH provided a rapid and efficient process to disrupt the microbial cells in the sludge. The results suggested that when irradiated at 800 W MW for 110 s with a dose of 1.0 g ACF/g solid concentration (SS) at pH 10.5, the MW-ACF pretreatment achieved 55% SS disintegration, 23% greater than the value of MW alone (32%). The concentration of total nitrogen, total phosphorus, supernatant soluble chemical oxygen demand, protein, and polysaccharide increased by 60%, 144%, 145%, 74%, and 77%, respectively. An increase in biogas production by 63.7% was achieved after 20 days of anaerobic digestion (AD), compared to the control. The results indicated that the MW-ACF pretreatment process at alkaline pH provides novel sludge management options in disintegration of sewage sludge for further AD. PMID:27332832

  5. The Surface Finish of Thermally Aged Carbon Fibre Reinforced Composites Using E-glass as a Surface Barrier

    NASA Astrophysics Data System (ADS)

    de Souza, M. L.; Fox, B. L.

    2015-10-01

    This work investigated the effect of woven E-glass mass (25 g/m2, 50 g/m2, 85 g/m2, 135 g/m2) on the painted surface finish of various thermoset (EPIKOTETM RIM935, EPIKOTETM 04434, Ultratec LpTM ES300, Ultratec LpTM SPV6035) carbon fibre composite laminates, before and after aging at 95 °C for 168 h. The as-moulded laminate surfaces were evaluated using surface profilometry techniques and the painted and aged surfaces were evaluated using a wave-scan distinctness of image (DOI) instrument. It was found that the 25 g/m2 E-glass surface layer assisted with reducing the roughness of the as-moulded surfaces and the long-term waviness of the painted surfaces due to the increase in resin-richness at the surface. The EPIKOTETM 04434 resin system that contained diglycidyl ether of bisphenol F (DGEBF) epoxy had the least change in long-term waviness with thermal aging due to the rigid fluorene-based backbone in comparison to the diglycidyl ether of bisphenol A (DGEBA) systems.

  6. Factors determining properties of multi-walled carbon nanotubes/fibres deposited by PECVD

    NASA Astrophysics Data System (ADS)

    Bell, M. S.; Teo, K. B. K.; Milne, W. I.

    2007-04-01

    This paper presents a number of factors which have been found to be important to the growth of carbon nanotubes and nanofibres by plasma enhanced chemical vapour deposition. The effect of the electric field in a plasma discharge on nanotube growth is investigated and shown to be important in achieving nanotube alignment. The use of a plasma discharge also enables deposition to take place at lower temperatures, facilitating the use of substrates which would otherwise be damaged. The effect of varying the ratio of carbon feedstock gas to etchant gas is investigated and the ratio is shown to be important for controlling the shape of deposited nanostructures. The effects of varying plasma power are investigated, showing that greater plasma power results in a lower growth rate. Higher levels of plasma power are also shown to cause the sidewalls of deposited carbon nanotubes to be etched. Finally, the growth rate of carbon nanotubes and nanofibres is shown to depend upon the strength of the local electric field. It is proposed that a higher field causes greater ionization within the plasma, which results in a higher growth rate. This is borne out by comparing simulation results with experimental observations.

  7. High energy flux thermo-mechanical test of 1D-carbon-carbon fibre composite prototypes for the SPIDER diagnostic calorimeter

    SciTech Connect

    De Muri, M. Pasqualotto, R.; Dalla Palma, M.; Cervaro, V.; Fasolo, D.; Franchin, L.; Tollin, M.; Serianni, G.; Cavallin, T.; Greuner, H.; Böswirth, B.

    2014-02-15

    Operation of the thermonuclear fusion experiment ITER requires additional heating via injection of neutral beams from accelerated negative ions. In the SPIDER test facility, under construction in Padova, the production of negative ions will be studied and optimised. STRIKE (Short-Time Retractable Instrumented Kalorimeter Experiment) is a diagnostic used to characterise the SPIDER beam during short pulse operation (several seconds) to verify if the beam meets the ITER requirements about the maximum allowed beam non-uniformity (below ±10%). The major components of STRIKE are 16 1D-CFC (Carbon-Carbon Fibre Composite) tiles, observed at the rear side by a thermal camera. This contribution gives an overview of some tests under high energy particle flux, aimed at verifying the thermo-mechanical behaviour of several CFC prototype tiles. The tests were performed in the GLADIS facility at IPP (Max-Plank-Institut für Plasmaphysik), Garching. Dedicated linear and nonlinear simulations were carried out to interpret the experiments and a comparison of the experimental data with the simulation results is presented. The results of some morphological and structural studies on the material after exposure to the GLADIS beam are also given.

  8. High energy flux thermo-mechanical test of 1D-carbon-carbon fibre composite prototypes for the SPIDER diagnostic calorimeter.

    PubMed

    De Muri, M; Cavallin, T; Pasqualotto, R; Dalla Palma, M; Cervaro, V; Fasolo, D; Franchin, L; Tollin, M; Greuner, H; Böswirth, B; Serianni, G

    2014-02-01

    Operation of the thermonuclear fusion experiment ITER requires additional heating via injection of neutral beams from accelerated negative ions. In the SPIDER test facility, under construction in Padova, the production of negative ions will be studied and optimised. STRIKE (Short-Time Retractable Instrumented Kalorimeter Experiment) is a diagnostic used to characterise the SPIDER beam during short pulse operation (several seconds) to verify if the beam meets the ITER requirements about the maximum allowed beam non-uniformity (below ±10%). The major components of STRIKE are 16 1D-CFC (Carbon-Carbon Fibre Composite) tiles, observed at the rear side by a thermal camera. This contribution gives an overview of some tests under high energy particle flux, aimed at verifying the thermo-mechanical behaviour of several CFC prototype tiles. The tests were performed in the GLADIS facility at IPP (Max-Plank-Institut für Plasmaphysik), Garching. Dedicated linear and nonlinear simulations were carried out to interpret the experiments and a comparison of the experimental data with the simulation results is presented. The results of some morphological and structural studies on the material after exposure to the GLADIS beam are also given.

  9. Fibre typing of intrafusal fibres

    PubMed Central

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

    2015-01-01

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

  10. Stimulated supercontinuum-radiation generation of carbon disulfide by all-trans-β-carotene fluorescence enhancement effect in liquid core optical fibre

    NASA Astrophysics Data System (ADS)

    Men, Zhi-Wei; Fang, Wen-Hui; Li, Zuo-Wei; Qu, Guan-Nan; Gao, Shu-Qin; Lu, Guo-Hui; Yang, Jian-Ge; Sun, Cheng-Lin

    2010-08-01

    We demonstrate stimulated supercontinuum-radiation of carbon disulfide (CS2) influenced by biological molecules all-trans-β-carotene in liquid core optical fibre (LCOF). By virtue of the broad fluorescence characteristics and large third-order optical nonlinearities of all-trans-β-carotene, the high-order Stokes lines of stimulated Raman scattering (SRS) and the multi-order Stokes lines of stimulated Brillouin scattering (SBS) excitated by SRS are observed at low input-laser energies. The results indicate that the fluorescence not only enhances the SRS, but also the SBS. These Stokes lines generate the SRS-SBS supercontinuum radiation (RBSR). A flat-amplitude bandwidth of 110 nm from 515 nm to 625 nm is observed when a frequency-doubled Nd:YAG laser at 532 nm with an energy of 0.86 mJ is used. This result is expected to be useful for the multi-wavelength fibre laser.

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

    PubMed

    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.

  12. Characterisation of the mechanical and fracture properties of a uni-weave carbon fibre/epoxy non-crimp fabric composite.

    PubMed

    Bru, Thomas; Hellström, Peter; Gutkin, Renaud; Ramantani, Dimitra; Peterson, Göran

    2016-03-01

    A complete database of the mechanical properties of an epoxy polymer reinforced with uni-weave carbon fibre non-crimp fabric (NCF) is established. In-plane and through-the-thickness tests were performed on unidirectional laminates under normal loading and shear loading. The response under cyclic shear loading was also measured. The material has been characterised in terms of stiffness, strength, and failure features for the different loading cases. The critical energy release rates associated with different failure modes in the material were measured from interlaminar and translaminar fracture toughness tests. The stress-strain data of the tensile, compressive, and shear test specimens are included. The load-deflection data for all fracture toughness tests are also included. The database can be used in the development and validation of analytical and numerical models of fibre reinforced plastics (FRPs), in particular FRPs with NCF reinforcements. PMID:26958626

  13. Characterisation of the mechanical and fracture properties of a uni-weave carbon fibre/epoxy non-crimp fabric composite.

    PubMed

    Bru, Thomas; Hellström, Peter; Gutkin, Renaud; Ramantani, Dimitra; Peterson, Göran

    2016-03-01

    A complete database of the mechanical properties of an epoxy polymer reinforced with uni-weave carbon fibre non-crimp fabric (NCF) is established. In-plane and through-the-thickness tests were performed on unidirectional laminates under normal loading and shear loading. The response under cyclic shear loading was also measured. The material has been characterised in terms of stiffness, strength, and failure features for the different loading cases. The critical energy release rates associated with different failure modes in the material were measured from interlaminar and translaminar fracture toughness tests. The stress-strain data of the tensile, compressive, and shear test specimens are included. The load-deflection data for all fracture toughness tests are also included. The database can be used in the development and validation of analytical and numerical models of fibre reinforced plastics (FRPs), in particular FRPs with NCF reinforcements.

  14. Characterisation of the mechanical and fracture properties of a uni-weave carbon fibre/epoxy non-crimp fabric composite

    PubMed Central

    Bru, Thomas; Hellström, Peter; Gutkin, Renaud; Ramantani, Dimitra; Peterson, Göran

    2016-01-01

    A complete database of the mechanical properties of an epoxy polymer reinforced with uni-weave carbon fibre non-crimp fabric (NCF) is established. In-plane and through-the-thickness tests were performed on unidirectional laminates under normal loading and shear loading. The response under cyclic shear loading was also measured. The material has been characterised in terms of stiffness, strength, and failure features for the different loading cases. The critical energy release rates associated with different failure modes in the material were measured from interlaminar and translaminar fracture toughness tests. The stress–strain data of the tensile, compressive, and shear test specimens are included. The load–deflection data for all fracture toughness tests are also included. The database can be used in the development and validation of analytical and numerical models of fibre reinforced plastics (FRPs), in particular FRPs with NCF reinforcements. PMID:26958626

  15. On the Motion of Carbon Nanotube Clusters near Optical Fiber Tips: Thermophoresis, Radiative Pressure, and Convection Effects.

    PubMed

    Vélez-Cordero, J Rodrigo; Hernández-Cordero, J

    2015-09-15

    We analyze the motion of multiwalled carbon nanotubes clusters in water or ethanol upon irradiation with a 975 and 1550 nm laser beam guided by an optical fiber. Upon measuring the velocities of the nanotube clusters in and out of the laser beam cone, we were able to identify thermophoresis, convection and radiation pressure as the main driving forces that determine the equilibrium position of the dispersion at low optical powers: while thermophoresis and convection pull the clusters toward the laser beam axis (negative Soret coefficient), radiation pressure pushes the clusters away from the fiber tip. A theoretical solution for the thermophoretic velocity, which considers interfacial motion and a repulsive potential interaction between the nanotubes and the solvent (hydrophobic interaction), shows that the main mechanism implicated in this type of thermophoresis is the thermal expansion of the fluid, and that the clusters migrate to hotter regions with a characteristic thermal diffusion coefficient D(T) of 9 × 10(-7) cm(2) K(-1) s(-1). We further show that the characteristic length associated with thermophoresis is not that of the nanotube clusters size, O(1) μm, but that corresponding to the microstructure of the clusters, O(1) nm. We finally discuss the role of the formation of gas-liquid interfaces (microbubbles) at high optical powers on the deposition of carbon nanotubes on the optical fiber end faces. PMID:26309145

  16. Tip Growth Of Carbon Nanotubes Obtained By Pyrolyzation Of Camphor Oil With Zeolite Embedded With Fe/Ni/Mn Catalyst

    NASA Astrophysics Data System (ADS)

    Azira, A. A.; Zainal, N. F. A.; Nik, S. F.; Rusop, M.

    2009-06-01

    Highly efficient synthesis of carbon nanotubes (CNTs) have been synthesized by thermal decomposition of camphor oil, on a zeolite support impregnated with Fe/Ni/Mn (molar ratio of Fe:Ni:Mn = 1:1:1) catalyst in the temperature range from 550-950° C by the thermal CVD method. Besides the surface fluidization of the catalyst nanoparticles themselves, assistance of the metal oxides embedded in zeolite supports is supposed to be responsible for high activity and selectivity of the Fe/Ni/Mn catalyst over which carbon source (camphor oil) successfully decomposes. The CNT yield was higher at 850° C and can be considered as the optimum deposition temperature. This result demonstrates that zeolite impregnated with the catalyst Fe/Ni/Mn is a suitable support for effective formation of CNTs. The morphological studies support `tip growth mechanism' for the growth of the CNT's in our case. The as-grown CNTs were characterized by FESEM and FTIR spectroscopy.

  17. Simulation study of structural, transport, and thermodynamic properties of TIP4P/2005 water in single-walled carbon nanotubes.

    PubMed

    Guse, Christa; Hentschke, Reinhard

    2012-01-19

    Because carbon nanotubes lack a strong interaction with water, its hydrogen bond network is altered mainly by the confining geometry alone, allowing one to study its influence on the structure of water. Here structural, transport, and thermodynamic properties are investigated for TIP4P/2005 water confined in single-walled carbon nanotubes, possessing diameters from 11 to 50 Å. Temperatures range from 220 to 600 K for the two pressures studied, 1 and 1000 atm. The results, based on grand canonical Monte Carlo techniques, include heats of adsorption, temperature and diameter dependent densities, density profiles, diffusion constants, and pressure tensor components. The main findings comprise the suppression of the density maximum in tubes with diameters below 50-25 Å, indicating that structures responsible for this anomaly are of comparable size. Furthermore the axial pressure can be described within the continuum limit with deviations only appearing for diameters below 20 Å. The diffusion constants are similar to that of bulk water, demonstrating that the agility of the hydrogen bond network is preserved in the confining geometries considered here.

  18. Defect Detection on Carbon Fibre Reinforced Plastics (cfrp) with Laser Generated Lamb Waves

    NASA Astrophysics Data System (ADS)

    Focke, O.; Huke, P.; Hildebrandt, A.

    2011-06-01

    Standard ultrasound methods using a phased-array or a single transducer are commonly used for non-destructive evaluation (NDE) during manufacturing of carbon fiber reinforced plastics (CFRP) parts and certificated testing schemes were developed for individual parts and geometries. However, most testing methods need direct contact, matching gels and remain therefore time consuming. Laser-Ultrasonics is advantageous due to the contactless measurement technology and high accessibility even on complex parts. Despite the non-destructive testing with body waves, we show that the NDE can be expanded using two-dimensional surface (Lamb) waves for detection of delaminations close to the surface or small deteriorations caused by e.g. impacts. Lamb waves have been excited with a single transducer and with a short-pulse Laser with additionally producing A0-and S0-Lamb waves. The waves were detected with a shearography setup that allows for measuring two-dimensionally the displacement of a surface. Short integration times of the camera were realized using a pulsed ruby laser for illumination. As a consequence to the anisotropy the propagation in different directions exhibits individual characteristics like amplitude, damping and velocity. This has motivated to build up models for the propagation of Lamb waves and to compare them with experimental results.

  19. Adsorption of toluene onto activated carbon fibre cloths and felts: application to indoor air treatment.

    PubMed

    Lorimier, C; Subrenat, A; Le Coq, L; Le Cloirec, P

    2005-11-01

    Due to their bad effects on human health, removing Volatile Organic Compounds from indoor air has become an issue of major interest. In this study, the potential use of six commercial activated carbon felts and cloths for indoor toluene removal was investigated. Both batch and dynamic adsorption studies were performed, at toluene concentrations ranging from 21 to 18160 mg m(-3), for an air velocity representative of indoor air treatment (0.37 m s(-1)). Batch measurements showed that felts exhibited higher adsorption capacities at equilibrium than cloths at high toluene concentrations, whereas this trend may be inverted at low concentrations. Experimental isotherms and kinetics were satisfactorily fitted by the Langmuir-Freundlich model and the Linear Driving Force model respectively. No main differences between the adsorption kinetics of felts and cloths were reported. Dynamic adsorption capacities at saturation appeared to be higher than 120 mg g(-1) for both cloths and felts, irrespective of relative humidity levels and toluene concentrations. The influence of relative humidity on the adsorption capacity of felts was not significant for the higher toluene concentration studied in dynamics (307 mg m(-3)), whereas an increase in relative humidity induced a decrease in adsorption capacity at the lower toluene concentration (38 mg m(-3)). Moreover, experimental curves of breakthrough time versus thickness of medium were satisfactorily fitted by the Adams-Bohart model, and the critical thickness determined by this model appeared to be below 1.3 mm, regardless of the medium or toluene concentration.

  20. DFT studies of COOH tip-functionalized zigzag and armchair single wall carbon nanotubes.

    PubMed

    Chełmecka, Elżbieta; Pasterny, Karol; Kupka, Teobald; Stobiński, Leszek

    2012-05-01

    Structure and energy calculations of pristine and COOH-modified model single wall carbon nanotubes (SWCNTs) of different length were performed at B3LYP/6-31G* level of theory. From 1 to 9 COOH groups were added at the end of the nanotube. The differences in structure and energetics of partially and fully functionalized SWCNTs at one end of the nanotube are observed. Up to nine COOH groups could be added at one end of (9,0) zigzag SWCNT in case of full functionalization. However, for (5,5) armchair SWCNT, the full functionalization was impossible due to steric crowding and rim deformation. The dependence of substituent attachment energy on the number of substituents at the carbon nanotube rim was observed.

  1. Theoretical modeling of temperature dependent catalyst-assisted growth of conical carbon nanotube tip by plasma enhanced chemical vapor deposition process

    SciTech Connect

    Tewari, Aarti; Sharma, Suresh C.

    2015-02-15

    A theoretical model has been developed to examine the effect of substrate temperature on the growth of the conical carbon nanotube (CNT) tip assisted by the catalyst in a reactive plasma. The growth rate of the CNT with conical tip because of diffusion and accretion of ions on catalyst nanoparticle including the charging rate of the CNT, kinetics of plasma species, and the evolution of the substrate temperature in reactive plasma has been taken into account. The effect of substrate temperature for different ion densities and temperatures on the growth of the conical CNT tip has been investigated for typical glow discharge plasma parameters. The results of the present model can serve as a major tool in better understanding of plasma heating effects on the growth of CNTs.

  2. Anterior cervical corpectomy: review and comparison of results using titanium mesh cages and carbon fibre reinforced polymer cages.

    PubMed

    Kabir, Syed M R; Alabi, J; Rezajooi, Kia; Casey, Adrian T H

    2010-10-01

    Different types of cages have recently become available for reconstruction following anterior cervical corpectomy. We review the results using titanium mesh cages (TMC) and stackable CFRP (carbon fibre reinforced polymer) cages. Forty-two patients who underwent anterior cervical corpectomy between November 2001 and September 2008 were retrospectively reviewed. Pathologies included cervical spondylotic myelopathy (CSM), cervical radiculopathy, OPLL (ossified posterior longitudinal ligament), metastasis/primary bone tumour, rheumatoid arthritis and deformity correction. All patients were evaluated clinically and radiologically. Outcome was assessed on the basis of the Odom's criteria, neck disability index (NDI) and myelopathy disability index (MDI). Mean age was 60 years and mean follow-up was 1½ years. Majority of the patients had single-level corpectomy. Twenty-three patients had TMC cages while 19 patients had CFRP cages. The mean subsidence noted with TMC cage was 1.91 mm, while with the stackable CFRP cage it was 0.5 mm. This difference was statistically significant (p < 0.05). However, there was no statistically significant correlation noted between subsidence and clinical outcome (p > 0.05) or between subsidence and post-operative sagittal alignment (p > 0.05) in either of the groups. Three patients had significant subsidence (> 3 mm), one of whom was symptomatic. There were no hardware-related complications. On the basis of the Odom's criterion, 9 patients (21.4%) had an excellent outcome, 14 patients (33.3%) had a good outcome, 9 patients (21.4%) had a fair outcome and 5 patients (11.9%) had a poor outcome, i.e. symptoms and signs unchanged or exacerbated. Mean post-operative NDI was 26.27% and mean post-operative MDI was 19.31%. Fusion was noted in all 42 cases. Both TMC and stackable CFRP cages provide solid anterior column reconstruction with good outcome following anterior cervical corpectomy. However, more subsidence is noted with TMC cages though

  3. Design and characterisation of a real time proton and carbon ion radiography system based on scintillating optical fibres.

    PubMed

    Lo Presti, D; Bonanno, D L; Longhitano, F; Bongiovanni, D G; Russo, G V; Leonora, E; Randazzo, N; Reito, S; Sipala, V; Gallo, G

    2016-09-01

    This paper describes the design and characterization of a charged particle imaging system composed of a position sensitive detector and residual range detector. The position detector consists of two identical overlying and orthogonal planes each of which consists of two layers of pre-aligned and juxtaposed scintillating fibres. The 500μm square section fibres are optically coupled to two Silicon Photomultiplier arrays using a channel reduction system patented by the Istituto Nazionale di Fisica Nucleare. The residual range detector consists of sixty parallel layers of the same fibres used in the position detector each of which is optically coupled to a Silicon Photomultiplier array by wavelength shifting fibres. The sensitive area of the two detectors is 9×9cm(2). Characterising the position sensitive and the residual range detectors to reconstruct the radiography, is fundamental to validating the detectors' designs. The proton radiography of a calibrated target in imaging conditions is presented. The spatial resolution of the position sensitive detector is about 150μm and the range resolution is about 170μm. The performance of the prototypes were tested at CATANA proton therapy facility (Laboratori Nazionali del Sud, INFN, Catania) with energy up to 58MeV and rate of about 10(6) particles per second. The comparison between the simulations and measurements confirms the validity of this system. PMID:27575280

  4. Design and characterisation of a real time proton and carbon ion radiography system based on scintillating optical fibres.

    PubMed

    Lo Presti, D; Bonanno, D L; Longhitano, F; Bongiovanni, D G; Russo, G V; Leonora, E; Randazzo, N; Reito, S; Sipala, V; Gallo, G

    2016-09-01

    This paper describes the design and characterization of a charged particle imaging system composed of a position sensitive detector and residual range detector. The position detector consists of two identical overlying and orthogonal planes each of which consists of two layers of pre-aligned and juxtaposed scintillating fibres. The 500μm square section fibres are optically coupled to two Silicon Photomultiplier arrays using a channel reduction system patented by the Istituto Nazionale di Fisica Nucleare. The residual range detector consists of sixty parallel layers of the same fibres used in the position detector each of which is optically coupled to a Silicon Photomultiplier array by wavelength shifting fibres. The sensitive area of the two detectors is 9×9cm(2). Characterising the position sensitive and the residual range detectors to reconstruct the radiography, is fundamental to validating the detectors' designs. The proton radiography of a calibrated target in imaging conditions is presented. The spatial resolution of the position sensitive detector is about 150μm and the range resolution is about 170μm. The performance of the prototypes were tested at CATANA proton therapy facility (Laboratori Nazionali del Sud, INFN, Catania) with energy up to 58MeV and rate of about 10(6) particles per second. The comparison between the simulations and measurements confirms the validity of this system.

  5. A novel method based on selective laser sintering for preparing high-performance carbon fibres/polyamide12/epoxy ternary composites.

    PubMed

    Zhu, Wei; Yan, Chunze; Shi, Yunsong; Wen, Shifeng; Liu, Jie; Wei, Qingsong; Shi, Yusheng

    2016-09-21

    A novel method based on selective laser sintering (SLS) process is proposed for the first time to prepare complex and high-performance carbon fibres/polyamide12/epoxy (CF/PA12/EP) ternary composites. The procedures are briefly described as follows: prepare polyamide12 (PA12) coated carbon fibre (CF) composite powder; build porous green parts by SLS; infiltrate the green parts with high-performance thermosetting epoxy (EP) resin; and finally cure the resin at high temperature. The obtained composites are a ternary composite system consisting of the matrix of novolac EP resin, the reinforcement of CFs and the transition thin layer of PA12 with a thickness of 595 nm. The SEM images and micro-CT analysis prove that the ternary system is a three-dimensional co-continuous structure and the reinforcement of CFs are well dispersed in the matrix of EP with the volume fraction of 31%. Mechanical tests show that the composites fabricated by this method yield an ultimate tensile strength of 101.03 MPa and a flexural strength of 153.43 MPa, which are higher than those of most of the previously reported SLS materials. Therefore, the process proposed in this paper shows great potential for manufacturing complex, lightweight and high-performance CF reinforced composite components in aerospace, automotive industries and other areas.

  6. A novel method based on selective laser sintering for preparing high-performance carbon fibres/polyamide12/epoxy ternary composites

    PubMed Central

    Zhu, Wei; Yan, Chunze; Shi, Yunsong; Wen, Shifeng; Liu, Jie; Wei, Qingsong; Shi, Yusheng

    2016-01-01

    A novel method based on selective laser sintering (SLS) process is proposed for the first time to prepare complex and high-performance carbon fibres/polyamide12/epoxy (CF/PA12/EP) ternary composites. The procedures are briefly described as follows: prepare polyamide12 (PA12) coated carbon fibre (CF) composite powder; build porous green parts by SLS; infiltrate the green parts with high-performance thermosetting epoxy (EP) resin; and finally cure the resin at high temperature. The obtained composites are a ternary composite system consisting of the matrix of novolac EP resin, the reinforcement of CFs and the transition thin layer of PA12 with a thickness of 595 nm. The SEM images and micro-CT analysis prove that the ternary system is a three-dimensional co-continuous structure and the reinforcement of CFs are well dispersed in the matrix of EP with the volume fraction of 31%. Mechanical tests show that the composites fabricated by this method yield an ultimate tensile strength of 101.03 MPa and a flexural strength of 153.43 MPa, which are higher than those of most of the previously reported SLS materials. Therefore, the process proposed in this paper shows great potential for manufacturing complex, lightweight and high-performance CF reinforced composite components in aerospace, automotive industries and other areas. PMID:27650254

  7. A novel method based on selective laser sintering for preparing high-performance carbon fibres/polyamide12/epoxy ternary composites.

    PubMed

    Zhu, Wei; Yan, Chunze; Shi, Yunsong; Wen, Shifeng; Liu, Jie; Wei, Qingsong; Shi, Yusheng

    2016-01-01

    A novel method based on selective laser sintering (SLS) process is proposed for the first time to prepare complex and high-performance carbon fibres/polyamide12/epoxy (CF/PA12/EP) ternary composites. The procedures are briefly described as follows: prepare polyamide12 (PA12) coated carbon fibre (CF) composite powder; build porous green parts by SLS; infiltrate the green parts with high-performance thermosetting epoxy (EP) resin; and finally cure the resin at high temperature. The obtained composites are a ternary composite system consisting of the matrix of novolac EP resin, the reinforcement of CFs and the transition thin layer of PA12 with a thickness of 595 nm. The SEM images and micro-CT analysis prove that the ternary system is a three-dimensional co-continuous structure and the reinforcement of CFs are well dispersed in the matrix of EP with the volume fraction of 31%. Mechanical tests show that the composites fabricated by this method yield an ultimate tensile strength of 101.03 MPa and a flexural strength of 153.43 MPa, which are higher than those of most of the previously reported SLS materials. Therefore, the process proposed in this paper shows great potential for manufacturing complex, lightweight and high-performance CF reinforced composite components in aerospace, automotive industries and other areas. PMID:27650254

  8. A novel method based on selective laser sintering for preparing high-performance carbon fibres/polyamide12/epoxy ternary composites

    NASA Astrophysics Data System (ADS)

    Zhu, Wei; Yan, Chunze; Shi, Yunsong; Wen, Shifeng; Liu, Jie; Wei, Qingsong; Shi, Yusheng

    2016-09-01

    A novel method based on selective laser sintering (SLS) process is proposed for the first time to prepare complex and high-performance carbon fibres/polyamide12/epoxy (CF/PA12/EP) ternary composites. The procedures are briefly described as follows: prepare polyamide12 (PA12) coated carbon fibre (CF) composite powder; build porous green parts by SLS; infiltrate the green parts with high-performance thermosetting epoxy (EP) resin; and finally cure the resin at high temperature. The obtained composites are a ternary composite system consisting of the matrix of novolac EP resin, the reinforcement of CFs and the transition thin layer of PA12 with a thickness of 595 nm. The SEM images and micro-CT analysis prove that the ternary system is a three-dimensional co-continuous structure and the reinforcement of CFs are well dispersed in the matrix of EP with the volume fraction of 31%. Mechanical tests show that the composites fabricated by this method yield an ultimate tensile strength of 101.03 MPa and a flexural strength of 153.43 MPa, which are higher than those of most of the previously reported SLS materials. Therefore, the process proposed in this paper shows great potential for manufacturing complex, lightweight and high-performance CF reinforced composite components in aerospace, automotive industries and other areas.

  9. Changing snow cover in tundra ecosystems tips the Arctic carbon balance

    NASA Astrophysics Data System (ADS)

    Zona, D.; Hufkens, K.; Gioli, B.; Kalhori, A. A. M.; Oechel, W. C.

    2014-12-01

    The Arctic environment has witnessed important changes due to global warming, resulting in increased surface air temperatures and rain events which both exacerbate snow cover deterioration (Semmens et al, 2013; Rennert et al, 2009; White et al, 2007; Min et al, 2008; Sharp et al, 2013; Schaeffer et al, 2013). Snow cover duration is declining by almost 20% per decade, a far higher rate than model estimates (Derksen and Brown, 2012). Concomitant with increasing temperatures and decreasing snow cover duration, the length of the arctic growing season is reported to have increased by 1.1 - 4.9 days per decade since 1951 (Menzel et al, 2006), and, plant productivity and CO2 uptake from arctic vegetation are strongly influenced by changes in growing season length (Myneni et al., 1997; Schaefer et al., 2005; Euskirchen et al., 2006). Based on more than a decade of eddy flux measurements in Arctic tundra ecosystems across the North slope of Alaska, and remotely sensed snow cover data, we show that earlier snow melt in the spring increase C uptake while an extended snow free period in autumn is associated with a higher C loss. Here we present the impacts of changes in snow cover dynamics between spring and autumn in arctic tundra ecosystems on the carbon dynamics and net C balance of the Alaskan Arctic. ReferencesDerksen, C., Brown R. (2012) Geophys. Res. Lett., doi:10.1029/2012GL053387 Euskirchen, E.S., et al. (2006) Glob. Change Biol., 12, 731-750. Menzel, A., et al. 2006. Glob. Change Biol., 12, 1969-1976. Min SK, Zhang X, Zweirs F (2008) Science 320: 518-520. Rennert K J, Roe G, Putkonen J and Bitz C M (2009) J. Clim. 22 2302-15. Schaefer, K., Denning A.S., Leonard O. (2005) Global Biogeochem. Cycles, 19, GB3017. Schaeffer, S. M., Sharp, E., Schimel, J. P. & Welker, J. M. (2013). Soil- plant N processes in a High Arctic ecosystem, NW Greenland are altered by long-term experimental warming and higher rainfall. Glob. Change Biol., 11, 3529-39. doi: 10.1111/gcb.12318

  10. Cell entry of one-dimensional nanomaterials occurs by tip recognition and rotation

    PubMed Central

    Shi, Xinghua; von dem Bussche, Annette; Hurt, Robert H.; Kane, Agnes B.; Gao, Huajian

    2011-01-01

    Materials with high aspect ratio, such as carbon nanotubes and asbestos fibres, have been shown to cause length-dependent toxicity in certain cells because these long materials prevent complete ingestion and this frustrates the cell1–3. Biophysical models have been proposed to explain how spheres and elliptical nanostructures enter cells4–8, but one-dimensional nanomaterials have not been examined. Here, we show experimentally and theoretically that cylindrical one-dimensional nanomaterials such as carbon nanotubes enter cells through the tip first. For nanotubes with end caps or carbon shells at their tips, uptake involves tip recognition through receptor binding, rotation that is driven by asymmetric elastic strain at the tube–bilayer interface, and near-vertical entry. The precise angle of entry is governed by the relative timescales for tube rotation and receptor diffusion. Nanotubes without caps or shells on their tips show a different mode of membrane interaction, posing an interesting question as to whether modifying the tips of tubes may help avoid frustrated uptake by cells. PMID:21926979

  11. Forest dynamics and tip-up pools drive pulses of high carbon accumulation rates in a tropical peat dome in Borneo (Southeast Asia)

    NASA Astrophysics Data System (ADS)

    Dommain, René; Cobb, Alexander R.; Joosten, Hans; Glaser, Paul H.; Chua, Amy F. L.; Gandois, Laure; Kai, Fuu-Ming; Noren, Anders; Salim, Kamariah A.; Su'ut, N. Salihah H.; Harvey, Charles F.

    2015-04-01

    Peatlands of Southeast Asia store large pools of carbon but the mechanisms of peat accumulation in tropical forests remain to be resolved. Patch dynamics and forest disturbance have seldom been considered as drivers that can amplify or dampen rates of peat accumulation. Here we used a modified piston corer, noninvasive geophysical measurements, and geochemical and paleobotanical techniques to establish the effect of tree fall on carbon accumulation rates in a peat swamp forest dominated by Shorea albida in Brunei (Borneo). Carbon initially accumulated in a mangrove forest at over 300 g C m-2 yr-1 but declined to less than 50 g C m-2 yr-1 with the establishment of a peat swamp forest. A rapid accumulation pulse of 720-960 g C m-2 yr-1 occurred around 1080 years ago as a tip-up pool infilled. Tip-up pools are common in the peatlands of northwest Borneo where windthrow and lightning strikes produce tree falls at a rate of 4 trees ha-1 every decade. A simulation model indicates that tip-up pools, which are formed across the entire forested peat dome, produce local discontinuities in the peat deposit, when peat is removed to create a pool that is rapidly filled with younger material. The resulting discontinuities in peat age at the base and sides of pool deposits obscure linkages between carbon accumulation rates and climate and require new approaches for paleoenvironmental reconstructions. Our results suggest that carbon accumulation in tropical peat swamps may be based on fundamentally different peat-forming processes than those of northern peatlands.

  12. Technology Tips

    ERIC Educational Resources Information Center

    Mathematics Teacher, 2004

    2004-01-01

    Some inexpensive or free ways that enable to capture and use images in work are mentioned. The first tip demonstrates the methods of using some of the built-in capabilities of the Macintosh and Windows-based PC operating systems, and the second tip describes methods to capture and create images using SnagIt.

  13. In-syringe dispersive micro-solid phase extraction using carbon fibres for the determination of chlorophenols in human urine by gas chromatography/mass spectrometry.

    PubMed

    García-Valverde, M T; Lucena, R; Cárdenas, S; Valcárcel, M

    2016-09-16

    In this article, carbon fibres (CFs) are presented as sorbent material for the dispersive micro-solid phase extraction of twelve chlorophenols from urine samples. CFs are synthesized by a reagentless and green procedure consisting of heating raw cotton, a natural precursor, at high temperature (400°C) in an inert atmosphere (Ar) during 2h. The resulting fibres, which present good water dispersibility, are finally loaded on an in-syringe device. This device, which integrates the extraction and final elution of the analytes, is disposable and it is adapted to process low sample volumes. Working at the optimum conditions, the extraction procedure in combination with gas chromatography/mass spectrometry allows the determination of the analytes in urine at the low μg/L range. In fact, the limits of quantification (LOQs) of the analytes were in the interval from 1μg/L to 2.5μg/L with precision values, expressed as relative standard deviations (RSD), better than 13%. Relative recovery values, ranging from 74.5% to 113%, demonstrate the applicability of the proposed method. PMID:27558356

  14. Carbon nanotubes-reinforced hollow fibre solid-phase microextraction coupled with high performance liquid chromatography for the determination of carbamate pesticides in apples.

    PubMed

    Song, Xin-Yue; Shi, Yan-Ping; Chen, Juan

    2013-08-15

    An effective and sensitive method to determinate five carbamate pesticides in apples was developed by using carbon nanotubes-reinforced hollow fibre solid-phase microextraction (CNTs-HF-SPME) combined with high performance liquid chromatography-photodiode array detection (HPLC-DAD). The CNTs were dispersed in water via adding surfactant, and then were held in the pores of HF supported by capillary forces and sonification. The SPME device, which was wetted with 1-octanol, was placed in a stirred apple samples to extract target analytes. After extraction, analytes were desorbed and analyzed using HPLC-DAD. Under the optimized extraction conditions, the enrichment factors were achieved in the range from 49 to 308 with good inter-fibre repeatability and batch-to-batch reproducibility, while good linearity ranges and recoveries were obtained. The limits of detection ranged from 0.09 to 6.00 ng/g. Therefore, the results demonstrated that this novel method was an efficient pretreatment and enrichment procedure for the determination of trace carbamate pesticides in apples.

  15. Experimental study of laser-oxygen cutting of low-carbon steel using fibre and CO{sub 2} lasers under conditions of minimal roughness

    SciTech Connect

    Golyshev, A A; Malikov, A G; Orishich, A M; Shulyatyev, V B

    2014-10-31

    The results of an experimental study of laser-oxygen cutting of low-carbon steel using fibre and CO{sub 2} lasers are generalised. The dependence of roughness of the cut surface on the cutting parameters is investigated, and the conditions under which the surface roughness is minimal are formulated. It is shown that for both types of lasers these conditions can be expressed in the same way in terms of the dimensionless variables – the Péclet number Pe and the output power Q of laser radiation per unit thickness of the cut sheet – and take the form of the similarity laws: Pe = const, Q = const. The optimal values of Pe and Q are found. We have derived empirical expressions that relate the laser power and cutting speed with the thickness of the cut sheet under the condition of minimal roughness in the case of cutting by means of radiation from fibre and CO{sub 2} lasers. (laser technologies)

  16. Stress-strain behaviour of IM7/977-2 and IM7/APC2 carbon fibre composites at low and high strain rates

    NASA Astrophysics Data System (ADS)

    Parry, D. J.; Al-Hazmi, F. S.

    2003-09-01

    The dynamic compressive behaviour of two IM7 carbon fibre composite systems has been studied at room temperature at strain rates from about 10^{-3} s^{-1} to 10^3 s^{-1}. A Hopkinson bar method was used for high rates and a conventional screw machine for low rates. One composite system (IM7/977-2) has a thermoset epoxy resin matrix toughened with thermoplastic material; the other system (IM7/APC2) has a thermoplastic PEEK matrix. Three types of fibre configuration were used for each system: (a) longitudinal unidirectional, 0° (LU), (b) transverse unidirectional, 90° (TU), and (c) transverse isotropic, (0°/90°/±45°)s (TI). At low rates, both systems showed similar stress-strain behaviour. For the LU types, the fracture stresses were about 790 MPa, while for the TU types the values were about 235 MPa. For the Tl specimens, the maximum available stress of 950 MPa was insufficient for fracture. At high rates, the fracture stress was about 25% greater than the quasistatic values for both LU types, and about 30% higher for both TU types. The major difference between the two systems was with the TI types: the energy density to fracture was about 65 MJ m^{-3} for the epoxy composite, while it was about 40 MJ m^{-3} for the PEEK composite.

  17. Simulator trials to determine the wear of the combination aluminium oxide ceramic-carbon fibre reinforced plastic (CFRP) used as an insert in a hip socket.

    PubMed

    Scheller, G; Schwarz, M; Früh, H J; Jani, L

    1999-01-01

    Hip simulator trials were conducted to determine the initial wear between alumina femoral heads and carbon fibre reinforced plastic (CFRP, CAPROMAN) insert in a titanium socket. A force of 2500 N and a frequency of 0.857 H were applied. Using surface and sphericity measurement techniques, the amount of wear was determined. After 500,000 cycles, the centre of the head had moved by 10 microm into the insert, and the average radius increased by 2 microm. After 1 million cycles, the additional changes were less than 1 microm. Based on an examination of retrieved implants (wear rate: 6.1 microm/year) and based on the simulator results, the combination alumina-CFRP inserts could be approved for total hip replacement.

  18. Lung counting: comparison of detector performance with a four detector array that has either metal or carbon fibre end caps, and the effect on mda calculation.

    PubMed

    Ahmed, Asm Sabbir; Hauck, Barry; Kramer, Gary H

    2012-08-01

    This study described the performance of an array of high-purity Germanium detectors, designed with two different end cap materials-steel and carbon fibre. The advantages and disadvantages of using this detector type in the estimation of the minimum detectable activity (MDA) for different energy peaks of isotope (152)Eu were illustrated. A Monte Carlo model was developed to study the detection efficiency for the detector array. A voxelised Lawrence Livermore torso phantom, equipped with lung, chest plates and overlay plates, was used to mimic a typical lung counting protocol with the array of detectors. The lung of the phantom simulated the volumetric source organ. A significantly low MDA was estimated for energy peaks at 40 keV and at a chest wall thickness of 6.64 cm.

  19. Tipping Points

    NASA Astrophysics Data System (ADS)

    Hansen, J.

    2007-12-01

    A climate tipping point, at least as I have used the phrase, refers to a situation in which a changing climate forcing has reached a point such that little additional forcing (or global temperature change) is needed to cause large, relatively rapid, climate change. Present examples include potential loss of all Arctic sea ice and instability of the West Antarctic and Greenland ice sheets. Tipping points are characterized by ready feedbacks that amplify the effect of forcings. The notion that these may be runaway feedbacks is a misconception. However, present "unrealized" global warming, due to the climate system's thermal inertia, exacerbates the difficulty of avoiding global warming tipping points. I argue that prompt efforts to slow CO2 emissions and absolutely reduce non-CO2 forcings are both essential if we are to avoid tipping points that would be disastrous for humanity and creation, the planet as civilization knows it.

  20. Tipping Point

    MedlinePlus

    ... Tipping Point by CPSC Blogger September 22 appliance child Childproofing CPSC danger death electrical fall furniture head injury product safety television tipover tv Watch the video in Adobe Flash format. Almost weekly, we see ...

  1. Microstructure characterization of advanced protective Cr/CrN+a-C:H/a-C:H:Cr multilayer coatings on carbon fibre composite (CFC).

    PubMed

    Major, L; Janusz, M; Lackner, J M; Kot, M; Major, B

    2016-06-01

    Studies of advanced protective chromium-based coatings on the carbon fibre composite (CFC) were performed. Multidisciplinary examinations were carried out comprising: microstructure transmission electron microscopy (TEM, HREM) studies, micromechanical analysis and wear resistance. Coatings were prepared using a magnetron sputtering technique with application of high-purity chromium and carbon (graphite) targets deposited on the CFC substrate. Selection of the CFC for surface modification in respect to irregularities on the surface making the CFC surface more smooth was performed. Deposited coatings consisted of two parts. The inner part was responsible for the residual stress compensation and cracking initiation as well as resistance at elevated temperatures occurring namely during surgical tools sterilization process. The outer part was responsible for wear resistance properties and biocompatibility. Experimental studies revealed that irregularities on the substrate surface had a negative influence on the crystallites growth direction. Chromium implanted into the a-C:H structure reacted with carbon forming the cubic nanocrystal chromium carbides of the Cr23 C6 type. The cracking was initiated at the coating/substrate interface and the energy of brittle cracking was reduced because of the plastic deformation at each Cr interlayer interface. The wear mechanism and cracking process was described in micro- and nanoscale by means of transmission electron microscope studies. Examined materials of coated CFC type would find applications in advanced surgical tools.

  2. Microstructure characterization of advanced protective Cr/CrN+a-C:H/a-C:H:Cr multilayer coatings on carbon fibre composite (CFC).

    PubMed

    Major, L; Janusz, M; Lackner, J M; Kot, M; Major, B

    2016-06-01

    Studies of advanced protective chromium-based coatings on the carbon fibre composite (CFC) were performed. Multidisciplinary examinations were carried out comprising: microstructure transmission electron microscopy (TEM, HREM) studies, micromechanical analysis and wear resistance. Coatings were prepared using a magnetron sputtering technique with application of high-purity chromium and carbon (graphite) targets deposited on the CFC substrate. Selection of the CFC for surface modification in respect to irregularities on the surface making the CFC surface more smooth was performed. Deposited coatings consisted of two parts. The inner part was responsible for the residual stress compensation and cracking initiation as well as resistance at elevated temperatures occurring namely during surgical tools sterilization process. The outer part was responsible for wear resistance properties and biocompatibility. Experimental studies revealed that irregularities on the substrate surface had a negative influence on the crystallites growth direction. Chromium implanted into the a-C:H structure reacted with carbon forming the cubic nanocrystal chromium carbides of the Cr23 C6 type. The cracking was initiated at the coating/substrate interface and the energy of brittle cracking was reduced because of the plastic deformation at each Cr interlayer interface. The wear mechanism and cracking process was described in micro- and nanoscale by means of transmission electron microscope studies. Examined materials of coated CFC type would find applications in advanced surgical tools. PMID:26788794

  3. Carbon nanotubes fibres/aluminium-NiZnFe2O4 based electromagnetic transmitter for improved magnitude versus offset (MVO) in a scaled marine environment.

    PubMed

    Yahya, Noorhana; Akhtar, Majid Niaz; Nasir, Nadeem; Shafie, Afza; Jabeli, Maryam Sharifi; Koziol, Krzysztof

    2012-10-01

    In seabed logging the magnitude of electromagnetic (EM) waves for the detection of a hydrocarbon reservoir in the marine environment is very important. Having a strong EM source for exploration target 4000 m below the sea floor is a very challenging task. A new carbon nanotubes (CNT) fibres/aluminium based EM transmitter is developed and NiZn ferrite as magnetic feeders was used in a scaled tank to evaluate the presence of oil. Resistive scaled tank experiments with a scale factor of 2000 were carried out. X-ray Diffraction (XRD), Raman Spectroscopy and Field Emission Scanning Electron Microscope (FESEM) were done to characterize the synthesized magnetic feeders. Single phase Ni0.76Mg0.04Zn0.2Fe2O4, obtained by the sol-gel method and sintered at 700 degrees C in air, has a [311] major peak. FESEM results show nanoparticles with average diameters of 17-45 nm. Samples which have a high Q-factor (approximately 50) was used as magnetic feeders for the EM transmitter. The magnitude of the EM waves of this new EM transmitter increases up to 400%. A curve fitting method using MATLAB software was done to evaluate the performance of the new EM transmitter. The correlation value with CNT fibres/aluminium-NiZnFe2O4 base transmitter shows a 152.5% increase of the magnetic field strength in the presence of oil. Modelling of the scale tank which replicates the marine environment was done using the Finite Element Method (FEM). In conclusion, FEM was able to delineate the presence of oil with greater magnitude of E-field (16.89%) and the B field (4.20%) due to the new EM transmitter. PMID:23421185

  4. Carbon nanotubes fibres/aluminium-NiZnFe2O4 based electromagnetic transmitter for improved magnitude versus offset (MVO) in a scaled marine environment.

    PubMed

    Yahya, Noorhana; Akhtar, Majid Niaz; Nasir, Nadeem; Shafie, Afza; Jabeli, Maryam Sharifi; Koziol, Krzysztof

    2012-10-01

    In seabed logging the magnitude of electromagnetic (EM) waves for the detection of a hydrocarbon reservoir in the marine environment is very important. Having a strong EM source for exploration target 4000 m below the sea floor is a very challenging task. A new carbon nanotubes (CNT) fibres/aluminium based EM transmitter is developed and NiZn ferrite as magnetic feeders was used in a scaled tank to evaluate the presence of oil. Resistive scaled tank experiments with a scale factor of 2000 were carried out. X-ray Diffraction (XRD), Raman Spectroscopy and Field Emission Scanning Electron Microscope (FESEM) were done to characterize the synthesized magnetic feeders. Single phase Ni0.76Mg0.04Zn0.2Fe2O4, obtained by the sol-gel method and sintered at 700 degrees C in air, has a [311] major peak. FESEM results show nanoparticles with average diameters of 17-45 nm. Samples which have a high Q-factor (approximately 50) was used as magnetic feeders for the EM transmitter. The magnitude of the EM waves of this new EM transmitter increases up to 400%. A curve fitting method using MATLAB software was done to evaluate the performance of the new EM transmitter. The correlation value with CNT fibres/aluminium-NiZnFe2O4 base transmitter shows a 152.5% increase of the magnetic field strength in the presence of oil. Modelling of the scale tank which replicates the marine environment was done using the Finite Element Method (FEM). In conclusion, FEM was able to delineate the presence of oil with greater magnitude of E-field (16.89%) and the B field (4.20%) due to the new EM transmitter.

  5. TIP list

    SciTech Connect

    Ludwig, M E

    2006-06-22

    Subcontractors and vendors providing services, including the installation of purchased goods, are required to complete a TIP List. This list does not include every Environment, Safety, and Health (ES&H) related concern at LLNL. It is intended to highlight major concerns common to most on-site service activities.

  6. Technology Tips

    ERIC Educational Resources Information Center

    Santos-Trigo, Manuel

    2004-01-01

    A dynamic program for geometry called Cabri Geometry II is used to examine properties of figures like triangles and make connections with other mathematical ideas like ellipse. The technology tip includes directions for creating such a problem with technology and suggestions for exploring it.

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

    PubMed

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

    2015-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

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

    PubMed

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

    2015-12-01

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

  10. Pitch-based carbon-fibre-reinforced poly (ether-ether-ketone) OPTIMA assessed as a bearing material in a mobile bearing unicondylar knee joint.

    PubMed

    Scholes, S C; Unsworth, A

    2009-01-01

    The introduction of unicondylar knee prostheses has allowed the preservation of the non-diseased compartment of the knee while replacing the diseased or damaged compartment. In an attempt to reduce the likelihood of aseptic loosening, new material combinations have been investigated within the laboratory. Tribological tests (friction, lubrication, and wear) were performed on metal-on-carbon-fibre-reinforced (CFR) poly (ether-ether-ketone) (PEEK) (pitch-based) mobile unicondylar knee prostheses up to 5 x 10(6) cycles. Both a loaded soak control and an unloaded soak control (both medial and lateral components) were used to compensate for weight change due to lubricant absorption. For this material combination the loaded soak control gave slightly lower wear for both the medial and the lateral components than did the unloaded soak control. The medial components gave higher steady state wear than the lateral components (1.70 mm3 per 10(6) cycles compared with 1.02 mm3 per 10(6) cycles with the loaded soak control). The results show that the CFR PEEK unicondylar knee joints performed well in these wear tests. They gave lower volumetric wear rates than conventional metal-on-ultra-high-molecular-weight polyethylene prostheses have given in the past when tested under similar conditions. The friction tests showed that, at physiological viscosities, these joints operated in the boundary-mixed-lubrication regime. The low wear produced by these joints seems to be a function of the material combination and not of the lubrication regime.

  11. Self-mode-locking in erbium-doped fibre lasers with saturable polymer film absorbers containing single-wall carbon nanotubes synthesised by the arc discharge method

    SciTech Connect

    Tausenev, Anton V; Konyashchenko, Aleksandr V; Obraztsova, Elena D; Konov, Vitalii I; Lobach, A S; Chernov, A I; Kryukov, P G; Dianov, Evgenii M

    2007-03-31

    We studied the ring and linear schemes of erbium-doped fibre lasers in which passive mode locking was achieved with the help of saturable absorbers made of high-optical quality films based on cellulose derivatives with dispersed single-wall carbon nanotubes. The films were prepared by the original method with the use of nanotubes synthesised by the arc discharge method. The films exhibit nonlinear absorption at a wavelength of 1.5 {mu}m. Pulses in the form of optical solitons of duration 1.17 ps at a wavelength of 1.56 {mu}m were generated in the ring scheme of the erbium laser. The average output power was 1.1 mW at a pulse repetition rate of 20.5 MHz upon pumping by the 980-nm, 25-mW radiation from a laser diode. The pulse duration in the linear scheme was reduced to 466 fs for the output power up to 4 mW and a pulse repetition rate of 28.5 MHz. The specific feature of these lasers is a low pump threshold in the regime of generation of ultrashort pulses. (letters)

  12. Preparation & characterization of SiO{sub 2} interface layer by dip coating technique on carbon fibre for C{sub f}/SiC composites

    SciTech Connect

    Kumar, Kundan; Jariwala, C. Pillai, R.; Chauhan, N.; Raole, P. M.

    2015-08-28

    Carbon fibres (C{sub f}) are one of the most important reinforced materials for ceramic matrix composites such as C{sub f} - SiC composites and they are generally sought for high temperature applications in as space application, nuclear reactor and automobile industries. But the major problem arise when C{sub f} reinforced composites exposed to high temperature in an oxidizing environment, C{sub f} react with oxygen and burnt away. In present work, we have studied the effect of silica (SiO{sub 2}) coating as a protective coating on C{sub f} for the C{sub f} / SiC composites. The silica solution prepared by the sol-gel process and coating on C{sub f} is done by dip coating technique with varying the withdrawing speed i.e. 2, 5, 8 mm/s with fixed dipping cycle (3 Nos.). The uniform silica coating on the C{sub f} is shown by the Scanning Electron Microscope (SEM) analysis. The tensile test shows the increase in tensile strength with respect to increase in withdrawing speed. The isothermal oxidation analysis confirmed enhancement of oxidation resistance of silica coated C{sub f} as compared tothe uncoated C{sub f}.

  13. Preparation & characterization of SiO2 interface layer by dip coating technique on carbon fibre for Cf/SiC composites

    NASA Astrophysics Data System (ADS)

    Kumar, Kundan; Jariwala, C.; Pillai, R.; Chauhan, N.; Raole, P. M.

    2015-08-01

    Carbon fibres (Cf) are one of the most important reinforced materials for ceramic matrix composites such as Cf - SiC composites and they are generally sought for high temperature applications in as space application, nuclear reactor and automobile industries. But the major problem arise when Cf reinforced composites exposed to high temperature in an oxidizing environment, Cf react with oxygen and burnt away. In present work, we have studied the effect of silica (SiO2) coating as a protective coating on Cf for the Cf / SiC composites. The silica solution prepared by the sol-gel process and coating on Cf is done by dip coating technique with varying the withdrawing speed i.e. 2, 5, 8 mm/s with fixed dipping cycle (3 Nos.). The uniform silica coating on the Cf is shown by the Scanning Electron Microscope (SEM) analysis. The tensile test shows the increase in tensile strength with respect to increase in withdrawing speed. The isothermal oxidation analysis confirmed enhancement of oxidation resistance of silica coated Cf as compared tothe uncoated Cf.

  14. Selective catalytic reduction (SCR) of NO by urea loaded on activated carbon fibre (ACF) and CeO2/ACF at 30 degrees C: the SCR mechanism.

    PubMed

    Zeng, Zheng; Lu, Pei; Li, Caiting; Zeng, Guangming; Jiang, Xiao; Zhai, Yunbo; Fan, Xiaopeng

    2012-06-01

    Selective catalytic reduction (SCR) of NO by urea loaded on rayon-based activated carbon fibre (ACF) and CeO2/ACF (CA) was studied at ambient temperature (30 degrees C) to establish a basic scheme for its reduction. Nitric oxide was found to be reduced to N2 with urea deposited on the ACF and CA. When oxygen was present, the greater the amount of loaded urea (20-60%), the greater the NO(x) conversions, which were between 72.03% and 77.30%, whereas the NO(x) conversions were about 50% when oxygen was absent. Moreover, when the urea was loaded on CA, a catalyst containing 40% urea/ACF loaded with 10% CeO2 (UCA4) could yield a NO(x) conversion of about 80% for 24.5 h. Based on the experimental results, the catalytic mechanisms of SCR with and without oxygen are discussed. The enhancing effect of oxygen resulted from the oxidation of NO to NO2, and urea was the main reducing agent in the SCR of loaded catalysts. ACF-C was the catalytic centre in the SCR of NO of ACF, while CeO2 of urea-loaded CA was the catalytic centre.

  15. Mechanical properties and strength retention of carbon fibre-reinforced liquid crystalline polymer (LCP/CF) composite: an experimental study on rabbits.

    PubMed

    Kettunen, J; Mäkelä, E A; Miettinen, H; Nevalainen, T; Heikkilä, M; Pohjonen, T; Törmälä, P; Rokkanen, P

    1998-07-01

    A novel composite material with ultra-high flexural strength and cortical-bone-matched elastic modulus made of liquid crystalline polymer reinforced with carbon fibres (LCP/CF) is described. Cylindrical rods of 3.2 mm diameter and 50 mm length were fabricated by a preimpregnation/pultrusion method. The initial mechanical properties of the LCP/CF rods were as follows: flexural strength 448 MPa, flexural modulus 43 GPa, shear strength 164 MPa, and interlaminar shear strength 15.3 MPa. In the in vitro study the LCP/CF rods were immersed in phosphate-buffered saline of 37 degrees C for 12, 24, and 52 weeks. In the in vivo study the LCP/CF rods were implanted into the medullary cavity of both femora and subcutaneous tissue of the New Zealand White rabbits for 12, 24, and 52 weeks. The flexural strength of the LCP/CF rods at 52 weeks was 463 MPa in saline, 467 MPa in the subcutaneous tissue and 466 MPa in the medullary cavity of the femur. The flexural modulus was 44.6, 48.9 and 46.2 GPa, respectively. The corresponding shear strength values were 160, 178 and 181 MPa. We conclude that the LCP/CF is a promising material for high-load applications and the LCP/CF rods retain their initial mechanical properties in one-year follow-up in vivo and in vitro.

  16. Mode I fatigue delamination onset of carbon fibre reinforced polymer with novel post-cure through-thickness reinforcement

    NASA Astrophysics Data System (ADS)

    Kourloufas, Christopher J.

    A novel trough thickness reinforcement (TTR) technique, proposed by Kravchenko et al., has been tested under mode I fatigue loading conditions in order to investigate characterisation of the onset of delamination growth in unidirectional 8552/IM7. The experimental results, following standard test method ASTM D6115-13, indicate that the mode I fatigue delamination onset behaviour can be altered by the inclusion of TTR both ahead and behind the crack tip. Tests have been conducted at a wide range of maximum displacement values, corresponding to percentages of the critical fracture toughness value determined for the maternal, GIC. The results were found to contain a high degree of scatter, that is thought to be a result of pin installation quality. The results of these experiments show that the cycles to delamination onset for a wide range of the critical value of strain energy release rate, G, can be increased with the inclusion of this novel TTR technique. Further research is required before the TTR technique properties are fully characterised. Research into understanding of the pin failure mechanisms in fatigue is highly recommended.

  17. Method for Measuring the Distribution of Adhesion Forces on Continuous Nanoscale Protrusions Using Carbon Nanofiber Tip on a Scanning Probe Microscope Cantilever.

    PubMed

    Shimoi, Norihiro; Abe, Daisuke

    2015-07-01

    The adhesion force on surfaces has received attention in numerous scientific and technological fields, including catalysis, thin-film growth, and tribology. Many applications require knowledge of the strength of these forces as a function of position in three dimensions, but until now such information has only been theoretically proposed. Here, we demonstrate an approach based on scanning probe microscopy that can obtain such data and be used to image the three-dimensional surface force field of continuous nanoscale protrusions. We present adhesion force maps with nanometer and nanonewton resolution that allow detailed characterization of the interaction between a surface and a thin carbon nanofiber (CNF) rod synthesized by plasma-enhanced chemical vapor deposition (PECVD) at the end of a tip on a scanning probe microscope cantilever in three dimensions. In these maps, the positions of all continuous nanoscale protrusions are identified and the differences in the adhesive forces among limited areas at inequivalent sites are quantified.

  18. Atomic force microscopy characterization of the surface wettability of natural fibres

    NASA Astrophysics Data System (ADS)

    Pietak, Alexis; Korte, Sandra; Tan, Emelyn; Downard, Alison; Staiger, Mark P.

    2007-01-01

    Natural fibres represent a readily available source of ecologically friendly and inexpensive reinforcement in composites with degradable thermoplastics, however chemical treatments of fibres are required to prepare feasible composites. It is desirable to characterize the surface wettability of fibres after chemical treatment as the polarity of cellulose-based fibres influences compatibility with a polymer matrix. Assessment of the surface wettability of natural fibres using conventional methods presents a challenge as the surfaces are morphologically and chemically heterogeneous, rough, and can be strongly wicking. In this work it is shown that under atmospheric conditions the adhesion force between an atomic force microscopy (AFM) tip and the fibre surface can estimate the water contact angle and surface wettability of the fibre. AFM adhesion force measurements are suitable for the more difficult surfaces of natural fibres and in addition allow for correlations between microstructural features and surface wettability characteristics.

  19. Restorative Case Report: Flexibility of Fibre-Posts.

    PubMed

    Lancaster, Paula E

    2015-06-01

    Restoration of an anterior root-filled tooth with little remaining coronal tooth-tissue can utilise a post to retain a core, enabling definitive restoration. Post material was, until recently, primarily metal--be it cast or prefabricated. Currently, fibre-posts are promoted as being advantageous due to a favourable failure mechanism which may protect the root from fracture. This Case Report demonstrates failure of the structural integrity of a fibre-post in a maxillary lateral incisor, with a proposed explanation. Retreatment employed a diamond-coated ultrasonic tip for removal of the residual fibre-post and restoration with a cast-post and metal ceramic crown.

  20. Investigations into the damage for various types of unprotected carbon fibre composites with a variety of lightning arc attachments

    NASA Technical Reports Server (NTRS)

    Reid, G. W.

    1991-01-01

    Very little quantitative information exists on the extent and nature of damage caused to unprotected carbon fiber composites (CFC's) due to lightning arc attachment. An initial investigation into the arc damage to three different types and various thickness of CFC's from A and C component type lightning discharges is described. The difference in damage which the two types of waveform produced and the way the area of damage varies with different levels of action integral and charge transfer is compared. In some cases, the temperature rise at the rear of the panels was recorded for various levels of action integral and charge transfer. A comparison was made of the area of damage from visual inspection and soft x ray photography, using a suitable penetrant in the damage area. It is concluded there is a need for a more detailed analysis of the damage.

  1. Molecularly imprinted polymer solid-phase extraction coupled to square wave voltammetry at carbon fibre microelectrodes for the determination of fenbendazole in beef liver.

    PubMed

    Guzmán-Vázquez de Prada, A; Loaiza, Oscar A; Serra, B; Morales, D; Martínez-Ruiz, P; Reviejo, A J; Pingarrón, J M

    2007-05-01

    A molecularly imprinted polymer was developed and used for solid-phase extraction (MISPE) of the antihelmintic fenbendazole in beef liver samples. Detection of the analyte was accomplished using square wave voltammetry (SWV) at a cylindrical carbon fibre microelectrode (CFME). A mixture of MeOH/HAc (9:1) was employed both as eluent in the MISPE system and as working medium for electrochemical detection of fenbendazole. The limit of detection was 1.9x10(-7) mol L-1 (57 microg L-1), which was appropriate for the determination of fenbendazole at the maximum residue level permitted by the European Commission (500 microg kg-1 in liver). Given that the SW voltammetric analysis could not be directly performed in the sample extract as a consequence of interference from some sample components, a sample clean-up with a MIP for selectively retaining fenbendazole was performed. The MIP was synthesized using a 1:8:22 template/methacrylic acid/ethylene glycol dimethacrylate ratio. A Britton-Robinson Buffer of pH 9.0 was selected for retaining fenbendazole in the MIP cartridges, and an eluent volume of 5.0 mL at a flow rate of 2.0 mL min-1 was chosen in the elution step. Cross-reactivity with the MIP was observed for other benzimidazoles. The synthesized MIP exhibited a good selectivity for benzimidazoles with respect to other veterinary drugs. The applicability of the MISPE-SWV method was tested with beef liver samples, spiked with fenbendazole at 5,000 and 500 microg kg-1. Results obtained for ten different liver samples yielded mean recoveries of (95+/-12)% and (96+/-11)% for the upper and lower concentration level, respectively.

  2. Use of a novel carbon fibre composite material for the femoral stem component of a THR system: in vitro biological assessment.

    PubMed

    Scotchford, Colin A; Garle, Michael J; Batchelor, J; Bradley, John; Grant, David M

    2003-11-01

    A novel, low elastic modulus femoral component for THR has been developed using a composite of polyetheretherketone and carbon fibre. The objectives of this study were to investigate human osteoblast-like cell and macrophage responses to this material in vitro. Cells were grown on composite discs and controls. Osteoblast attachment and proliferation was not significantly different to that on Ti6Al4V. The levels of alkaline phosphatase activity, Type I collagen production and osteocalcin production were not significantly different to that on Ti6Al4V by the end of the experimental period. Hydrogen peroxide production by macrophages was significantly less than that detected for cells cultured on copper, but was still greater than that detected for cells cultured on tissue culture plastic and Ti6Al4V. Beta-glucoronidase activity was not significantly different to that detected for cells cultured on tissue culture plastic. The in vitro biocompatibility assessment of this composite undertaken in this study showed initial osteoblast attachment at least comparable to that of the tissue culture plastic and Ti6Al4V controls, with proliferation similar to the controls at all time points up to 11 days. Alkaline phosphatase activity was similar to that of Ti6Al4V but reduced compared to tissue culture plastic controls. Whilst hydrogen peroxide production by macrophages was raised on composite surfaces compared to controls, beta-glucoronidase activity and osteoblastic production of Type I collagen and osteocalcin were similar to levels detected on Ti6Al4V.

  3. Multimaterial piezoelectric fibres

    NASA Astrophysics Data System (ADS)

    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.

  4. Nanoscale PtSi Tips for Conducting Probe Technologies

    NASA Astrophysics Data System (ADS)

    Bhaskaran, Harish; Sebastian, Abu; Despont, Michel

    2009-01-01

    A method to improve the conduction and wear properties of nanometric conducting tips by forming silicides of Pt at the tip apex is presented. Tips with PtSi apexes are fabricated in conjunction with standard Si tips. Wear measurements are carried out on both tip types of similar geometries, and a one-on-one comparison between Si and PtSi at the nanoscale is shown for the first time. Both the wear properties on tetrahedral amorphous carbon and the conduction on Au of the PtSi tip apexes are shown to be superior to the Si tips.

  5. Droplet climbing on a pre-wetted conical fibre

    NASA Astrophysics Data System (ADS)

    Jian, Zhen; Li, Erqiang; Thoroddsen, S. T.

    We study the motion of a droplet on a wet conical fibre. The conical fibres are fabricated with a glass-puller, with tip diameters of several μm. With liquid is fed through the hollow fibre and travels up the outside of the cone, forming a droplet, which is initially attached near the tip. This drop grows in size and then detaches and moves on the fibre, at velocities up to 0.25 m/s. We focus on the regime with small Bond number Bo = ρgR2 / σ and capillary number Ca = μU / σ , where the droplet motion is driven by the pressure gradient due to the continuous curvature change along the conical fibre. High-speed imaging and numerical simulations via the Gerris code are employed to investigate the dynamics of the droplet detachment and climbing. Our focus is on the interface profile near the tip, the mechanism of droplet formation and climbing, and the velocity field in the thin liquid layer on the cone.

  6. Therapeutic role of dietary fibre.

    PubMed Central

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

    1993-01-01

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

  7. Fibre optics: Forty years later

    SciTech Connect

    Dianov, Evgenii M

    2010-01-31

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

  8. HIPPI and Fibre Channel

    SciTech Connect

    Tolmie, D.E.

    1992-01-01

    The High-Performance Parallel Interface (HIPPI) and Fibre Channel are near-gigabit per second data communications interfaces being developed in ANSI standards Task Group X3T9.3. HIPPI is the current interface of choice in the high-end and supercomputer arena, and Fibre Channel is a follow-on effort. HIPPI came from a local area network background, and Fibre Channel came from a mainframe to peripheral interface background.

  9. Development of novel composites through fibre and interface/interphase modification

    NASA Astrophysics Data System (ADS)

    Bismarck, A.; Blaker, JJ; Anthony, DB; Qian, H.; Maples, HA; Robinson, P.; Shaffer, MSP; Greenhalgh, ES

    2016-07-01

    We show how fibre/matrix interface (or interphase) modification can be used to develop a range of novel carbon fibre reinforced polymer (CFRP) composites that open up new applications far beyond those of standard CFRPs. For example, composites that undergo pseudo-ductile failure have been created through laser treatment of carbon fibres. Composites manufactured with thermo-responsive interphases can undergo significant reductions in stiffness at elevated temperatures. Additionally, structural supercapacitors have been developed through a process that involves encapsulating carbon fibres in carbon aerogel.

  10. Prom Health and Safety Tips

    MedlinePlus

    ... Healthy Occasions Autumn Tips Camping Tips Family Reunions Gardening Tips Halloween Tips Healthy Halloween Prom Tips Spring ... ways to stay active, such as walking, dancing, gardening, swimming, and more. Be active for 60 minutes ...

  11. Dietary fibre analysis.

    PubMed

    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. PMID:12740050

  12. Sensitive determination of bisphenol A and bisphenol F in canned food using a solid-phase microextraction fibre coated with single-walled carbon nanotubes before GC/MS.

    PubMed

    Rastkari, N; Ahmadkhaniha, R; Yunesian, M; Baleh, L J; Mesdaghinia, A

    2010-10-01

    A reliable and sensitive method for simultaneous determination of bisphenol A (BPA) and bisphenol F (BPF) in canned food by gas chromatography-mass spectrometry (GC/MS) is described after extraction and pre-concentration by a new solid-phase microextraction (SPME) adsorbent. The potential of single-walled carbon nanotubes (SWCNTs) as SPME adsorbent for the pre-concentration of environmental contaminants has been investigated in recent years. This work was carried out to investigate the feasibility of SWCNTs as a headspace SPME adsorbent for the determination of bisphenol derivatives in canned food. Potential factors affecting the extraction efficiency, including extraction time, extraction temperature, desorption time, desorption temperature, and salinity were optimized. Calibration curves were linear (r(2)> or = 0.994) over the concentration range from 0.30 to 60 microg kg(-1). For both target analytes, the limit of detection (LOD) at signal-to-noise (S/N) ratio of 3 was 0.10 microg kg(-1). In addition, a comparative study between the SWCNT and a commercial polydimethylsiloxane (PDMS) SPME fibre for the determination of bisphenol derivatives in canned food was conducted. SWCNT fibre showed higher extraction capacity, better thermal stability (over 350 degrees C) and longer life span (over 150 times) than the commercial PDMS fibre. The method was successfully applied to determine BPA in canned food samples which were purchased from local markets. BPA was found in some of the samples within the concentration range from 0.5 to 5.2 microg kg(-1).

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

    NASA Astrophysics Data System (ADS)

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

    2006-05-01

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

  14. Optical Fibre Switch

    NASA Astrophysics Data System (ADS)

    Markatos, S.; Ayres, S.; Kreit, D.; Kerr, A.; Youngquist, R. C.; Giles, I. P.

    1987-10-01

    The design construction and operation of a thermally controlled optical fibre switch, based upon the lap/polish technique, is described in this paper. The lap/polish method allows access to the evanescent field in an optical fibre and coupling between two fibres can be controlled from zero to total power transfer by changing the refractive index of the oil in the coupling region. Such refractive index changes can be induced thermally by directly heating the matching oil at the interaction area, with forming heating elements close to the fibre core. Power coupling is then proportional to the current supplied to the electrodes. Results are presented showing the frequency response of tlio device.

  15. Fibres get functional

    NASA Astrophysics Data System (ADS)

    Graham-Rowe, Duncan

    2011-02-01

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

  16. Tip-enhanced Raman spectroscopic measurement of stress change in the local domain of epitaxial graphene on the carbon face of 4H-SiC(000-1).

    PubMed

    Suzuki, Toshiaki; Itoh, Tamitake; Vantasin, Sanpon; Minami, Satoshi; Kutsuma, Yasunori; Ashida, Koji; Kaneko, Tada-aki; Morisawa, Yusuke; Miura, Takeshi; Ozaki, Yukihiro

    2014-10-01

    We develop a bulk silver tip for tip-enhanced Raman scattering (TERS) and obtain TERS spectra of epitaxial graphene on the carbon face of 4H-SiC(000-1) with a high signal-to-noise ratio. Thanks to the high quality of TERS spectra we firstly find that the G band in the TERS spectra exhibits position-by-position variations in both lower wavenumber shifts and spectral broadening. The analysis of the variations reveals that the shifts and broadenings have a linear correlation between each other, indicating that the variations are induced by the position dependent local stress on graphene based on a uniaxial strain model. PMID:25140359

  17. Characterization of chemically and enzymatically treated hemp fibres using atomic force microscopy and spectroscopy

    NASA Astrophysics Data System (ADS)

    George, Michael; Mussone, Paolo G.; Abboud, Zeinab; Bressler, David C.

    2014-09-01

    The mechanical and moisture resistance properties of natural fibre reinforced composites are dependent on the adhesion between the matrix of choice and the fibre. The main goal of this study was to investigate the effect of NaOH swelling of hemp fibres prior to enzymatic treatment and a novel chemical sulfonic acid method on the physical properties of hemp fibres. The colloidal properties of treated hemp fibres were studied exclusively using an atomic force microscope. AFM imaging in tapping mode revealed that each treatment rendered the surface topography of the hemp fibres clean and exposed the individual fibre bundles. Hemp fibres treated with laccase had no effect on the surface adhesion forces measured. Interestingly, mercerization prior to xylanase + cellulase and laccase treatments resulted in greater enzyme access evident in the increased adhesion force measurements. Hemp fibres treated with sulfonic acid showed an increase in surface de-fibrillation and smoothness. A decrease in adhesion forces for 4-aminotoulene-3-sulfonic acid (AT3S) treated fibres suggested a reduction in surface polarity. This work demonstrated that AFM can be used as a tool to estimate the surface forces and roughness for modified fibres and that enzymatic coupled with chemical methods can be used to improve the surface properties of natural fibres for composite applications. Further, this work is one of the first that offers some insight into the effect of mercerization prior to enzymes and the effect on the surface topography. AFM will be used to selectively screen treated fibres for composite applications based on the adhesion forces associated with the colloidal interface between the AFM tip and the fibre surfaces.

  18. Diet and Exercise Tips

    MedlinePlus

    ... Health News & Publications Annual Meeting Calendar Diet and Exercise Tips Diet and Exercise Tips News media interested in covering the latest ... Health Statistics concludes that 35 percent of adults exercise regularly (more than 6 of 10 don’t), ...

  19. Child Transportation Safety Tips.

    ERIC Educational Resources Information Center

    National Highway Traffic Safety Administration (DOT), Washington, DC.

    This document presents nine tips regarding safe infant and child transportation, each tip explained in one to two pages. The tips are as follows: (1) quick safety seat checkup; (2) where should your child ride? (3) how to protect your new baby in the car; (4) what safety seat to use for a big baby or toddler? (5) how should preschool and school…

  20. Benefits of crimped and prestressed CFRP's over noncrimped fibres as reinforcement in machine elements

    NASA Astrophysics Data System (ADS)

    Kanellopoulos, Ioannis; Vasileiou, Ioannis; Kitsos, Ioannis

    2014-10-01

    In this paper, a representative volume element consisted of a single wavy carbon fibre engulfed in a thermoplastic rectangular matrix is studied in order to examine the effect ofnon-crimped carbon fibre, and specifically its waviness, at the mechanical behavior. In order to quantify these influences and their nonlinear elastic behavior, a plane strain analysis of this model was simulated with finite elements.

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

    SciTech Connect

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

    1999-06-30

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

  2. Chronological ageing of human hair keratin fibres.

    PubMed

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

    2010-12-01

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

  3. A Fibre Optic Sensor Of Physiological Parameters

    NASA Astrophysics Data System (ADS)

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

    1986-11-01

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

  4. Tie-fibre structure and organization in the knee menisci.

    PubMed

    Andrews, Stephen H J; Rattner, Jerome B; Abusara, Ziad; Adesida, Adetola; Shrive, Nigel G; Ronsky, Janet L

    2014-05-01

    The collagenous structure of the knee menisci is integral to the mechanical integrity of the tissue and the knee joint. The tie-fibre structure of the tissue has largely been neglected, despite previous studies demonstrating its correlation with radial stiffness. This study has evaluated the structure of the tie-fibres of bovine menisci using 2D and 3D microscopy techniques. Standard collagen and proteoglycan (PG) staining and 2D light microscopy techniques were conducted. For the first time, the collagenous structure of the menisci was evaluated using 3D, second harmonic generation (SHG) microscopy. This technique facilitated the imaging of collagen structure in thick sections (50-100 μm). Imaging identified that tie-fibres of the menisci arborize from the outer margin of the meniscus toward the inner tip. This arborization is associated with the structural arrangement of the circumferential fibres. SHG microscopy has definitively demonstrated the 3D organization of tie-fibres in both sheets and bundles. The hierarchy of the structure is related to the organization of circumferential fascicles. Large tie-fibre sheets bifurcate into smaller sheets to surround circumferential fascicles of decreasing size. The tie-fibres emanate from the lamellar layer that appears to surround the entire meniscus. At the tibial and femoral surfaces these tie-fibre sheets branch perpendicularly into the meniscal body. The relationship between tie-fibres and blood vessels in the menisci was also observed in this study. Tie-fibre sheets surround the blood vessels and an associated PG-rich region. This subunit of the menisci has not previously been described. The size of tie-fibre sheets surrounding the vessels appeared to be associated with the size of blood vessel. These structural findings have implications in understanding the mechanics of the menisci. Further, refinement of the complex structure of the tie-fibres is important in understanding the consequences of injury and disease

  5. Arctic climate tipping points.

    PubMed

    Lenton, Timothy M

    2012-02-01

    There is widespread concern that anthropogenic global warming will trigger Arctic climate tipping points. The Arctic has a long history of natural, abrupt climate changes, which together with current observations and model projections, can help us to identify which parts of the Arctic climate system might pass future tipping points. Here the climate tipping points are defined, noting that not all of them involve bifurcations leading to irreversible change. Past abrupt climate changes in the Arctic are briefly reviewed. Then, the current behaviour of a range of Arctic systems is summarised. Looking ahead, a range of potential tipping phenomena are described. This leads to a revised and expanded list of potential Arctic climate tipping elements, whose likelihood is assessed, in terms of how much warming will be required to tip them. Finally, the available responses are considered, especially the prospects for avoiding Arctic climate tipping points.

  6. Economics of tipping the climate dominoes

    NASA Astrophysics Data System (ADS)

    Lemoine, Derek; Traeger, Christian P.

    2016-05-01

    Greenhouse gas emissions can trigger irreversible regime shifts in the climate system, known as tipping points. Multiple tipping points affect each other’s probability of occurrence, potentially causing a `domino effect’. We analyse climate policy in the presence of a potential domino effect. We incorporate three different tipping points occurring at unknown thresholds into an integrated climate-economy model. The optimal emission policy considers all possible thresholds and the resulting interactions between tipping points, economic activity, and policy responses into the indefinite future. We quantify the cost of delaying optimal emission controls in the presence of uncertain tipping points and also the benefit of detecting when individual tipping points have been triggered. We show that the presence of these tipping points nearly doubles today’s optimal carbon tax and reduces peak warming along the optimal path by approximately 1 °C. The presence of these tipping points increases the cost of delaying optimal policy until mid-century by nearly 150%.

  7. Nanomechanical measurements of hair as an example of micro-fibre analysis using atomic force microscopy nanoindentation.

    PubMed

    Clifford, Charles A; Sano, Naoko; Doyle, Peter; Seah, Martin P

    2012-03-01

    The characterisation of nanoscale surface properties of textile and hair fibres is key to developing new effective laundry and hair care products. Here, we develop nanomechanical methods to characterise fibres using an atomic force microscope (AFM) to give their nanoscale modulus. Good mounting methods for the fibre that are chemically inert, clean and give strong mechanical coupling to a substrate are important and here we detail two methods to do this. We show, for elastic nanoindentation measurements, the situation when the tip radius significantly affects the result via a function of the ratio of the radii of the tip and fibre and indicate the importance of using an AFM for such work. A valid method to measure the nanoscale modulus of fibres using AFM is thus detailed and exampled on hair to show that bleaching changes the nanoscale reduced modulus at the outer surface.

  8. Myocardial fibre calcification.

    PubMed Central

    McClure, J; Pieterse, A S; Pounder, D J; Smith, P S

    1981-01-01

    Three cases of myocardial fibre calcification found at post-mortem examination are described. In one case there was antemortem hypercalcaemia and hyperphosphataemia and the case was clearly an example of metastatic calcification. In the other two cases there was ischaemic myocardial necrosis and calcification was seen in fibres which were not overtly necrotic, but which were both in proximity to (the majority) and remote from the necrotic zones. Since renal failure with hyperphosphataemia was present in both cases, these were considered to be examples of augmented (by the hyperphosphataemia) dystrophic calcification. The histological, histochemical and ultrastructural features were identical in the three cases. Hydroxyapatite formation was observed initially in mitochondria, followed by spillage of crystals into the cytosol and ultimately into the interstitium. It is suggested that the fundamental lesion is a dysfunction of the fibre membrane; the similarity of this reaction with the calcification seen in skeletal muscle fibres in various myopathies is noted and a unifying hypothesis of the mechanism of skeletal and cardiac muscle fibre calcification is thereby suggested. Images PMID:7309897

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

    NASA Astrophysics Data System (ADS)

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

    2009-11-01

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

  10. Investigating the particle to fibre transition threshold during electrohydrodynamic atomization of a polymer solution.

    PubMed

    Husain, O; Lau, W; Edirisinghe, M; Parhizkar, M

    2016-08-01

    Electrohydrodynamic atomization (EHDA) is a key research area for producing micro and nano-sized structures. This process can be categorized into two main operating regimes: electrospraying for particle generation and electrospinning for fibre production. Producing particles/fibres of the desired size or morphology depends on two main factors; properties of the polymeric solution used and the processing conditions including flow rate, applied voltage and collection distance. In this work the particle-fibre transition region was analyzed by changing the polymer concentration of PLGA poly (lactic-co-glycolic acid) in acetone between 2 and 25wt%. Subsequently the processing conditions were adjusted to study the optimum transition parameters. Additionally the EHDA configuration was also modified by adding a metallic plate to observe the deposition area. The diameter and the distance of the plate from the capillary tip were adjusted to investigate variations in particle and fibre morphologies as well. It was found that complete transition from particles to fibres occurs at 20wt% indicating concentration to be the dominant criterion. Low flow rates yielded fibres without beads. However the applied voltage and distance between the tip of the nozzle jetting the polymer solution and collector (working distance) did not yield definitive results. Reducing the collector distance and increasing applied voltages produces smooth as well as beaded fibres. Addition of a metal plate reduces particle size by ~1μm; the fibre size increases especially with increasing plate diameter while bead density and size reduces when the disc is fixed closer to the capillary tip. Additionally, the deposition area is reduced by 70% and 57% with the addition of metal plates of 30mm and 60mm, respectively. The results indicate that a metal plate can be utilized further to tune the particle/fibre size and morphology and this also significantly increases the yield of EHDA process which is currently a

  11. Laser Cutting of CFRP with a Fibre Guided High Power Nanosecond Laser Source - Influence of the Optical Fibre Diameter on Quality and Efficiency

    NASA Astrophysics Data System (ADS)

    Bluemel, S.; Bastick, S.; Staehr, R.; Jaeschke, P.; Suttmann, O.; Overmeyer, L.

    For the development of a robot based laser cutting process of automotive 3D parts consisting of carbon fibre reinforced plastics (CFRP), investigations with a newly developed fibre guided nanosecond pulsed laser with an average power of PL = 1.5 kW were conducted. In order to investigate the best combination of quality and process time 2 different optical fibres were used, with diameters of df = 400 μm and df = 600 μm. The main differences between the two setups are the resulting focal diameter and the maximum available pulse energy up to EP = 80 mJ. In a first instance, a comparable investigation was performed with both fibres for a constant pulse overlap. For each fibre the minimum required line energy was investigated and cuts were performed, distributed over the complete parameter range of the laser source. The influences of the fibre diameter on the quality and efficiency of the cutting process are summarized and discussed.

  12. Comportement en compression d'une fibre de carbone dans un composite modèle monofilamentaire : simulation des images observées en photoélasticité

    NASA Astrophysics Data System (ADS)

    Vigouroux, A.; Andrieux, M.; Sixou, P.

    1996-05-01

    Nous calculons les images observables en photoélasticité pour un composite monofilamentaire, constitué par une fibre de carbone de 7 ou 49 μm de diamètre dans une matrice époxyde, soumis à un effort de compression. Le modèle de microflambage initialement développé par Lee et Harris [21] et repris à l'O.N.E.R.A. par Grandsire-Vinçon [14] est utilisé. Il est possible d'obtenir les déformations principales, leur différence ainsi que les directions principales. En dehors de la couche qui contient le plan de microflambage de la fibre, il est pris en compte des couches supplémentaires qui correspondent aux couches de matières situées au-dessus et au-dessous du plan de microflambage de la fibre. Dans le cas de la fibre T300 (diamètre 7 μm), et pour une ondulation initiale de 0,5 μm, une période d'oscillation de 50 ou 100 μm et une compression globale comprise entre 1 et 3 %, les calculs réalisés avec ou sans couches supplémentaires et avec ou sans lames quart-d'onde montrent des images assez sombres : le contraste est faible et les déformations sont presque du même ordre de grandeur pour une image donnée. Dans le cas de la fibre C49 (diamètre 49 μm), le contraste est bien plus important. Les images colorimétriques présentent des modifications notables en fonction des différents paramètres que l'on peut faire varier et sont très voisines de l'expérience. Une discussion détaillée de ce cas a été réalisée. En particulier, la différence des déformations principales diminue sur à-peu-près une épaisseur de fibre autour de cette dernière ; on constate de plus une alternance des couleurs lorsque l'on fait varier l'angle entre polariseur et axe neutre de la fibre, et enfin les déformations sont plus importantes au niveau des parties concaves de l'ondulation que des parties convexes. Based on a compressed single embedded fiber composite, constituted with a 7 μm or 49 μm fiber in an epoxy matrix, photoelasticity observables images

  13. ADHD: Tips to Try

    MedlinePlus

    ... How Can I Help a Friend Who Cuts? ADHD: Tips to Try KidsHealth > For Teens > ADHD: Tips to Try Print A A A Text Size en español TDAH: Consejos que puedes probar ADHD , or attention deficit hyperactivity disorder, is a medical ...

  14. Total Telephone Tips.

    ERIC Educational Resources Information Center

    Corder, Lloyd E.; And Others

    This manual of telephone behavior tips for business and sales professionals offers ways to handle the disgruntled caller and makes suggestions on topics relevant to the telephone. The manual is divided into the following sections and subsections: (1) Common Courtesy (staff tips, answering the telephone, screening calls, transferring calls, taking…

  15. Air Travel Health Tips

    MedlinePlus

    MENU Return to Web version Air Travel Health Tips Air Travel Health Tips How can I improve plane travel? Most people don't have any problems when ... and dosages of all of your medicines. The air in airplanes is dry, so drink nonalcoholic, decaffeinated ...

  16. Parameters influencing the thermal expansion of polymers and fibre composites

    NASA Astrophysics Data System (ADS)

    Baschek, G.; Hartwig, G.

    Thermal expansion of polymers and fibre composites is an important design parameter in cryogenics. Measurements have been carried out with a laser interference dilatometer and an inductive dilatometer. Parameters which might influence the thermal expansion have been investigated. For polymers the influence of annealing has been studied. Annealing at a temperature near to the main glass transition yielded deviations of about 5% compared to those of untreated samples. The very large expansion of polymers can be drastically varied by reinforcement with fibres of different fibre arrangements. For carbon fibre angle-plies even negative expansion can be achieved (Humphreys, E.A. and Rosen, B.W., Properties analysis of laminates. In Engineered Materials Handbook, Vol. 1, Composites. ASM International, USA, 1987, p. 226). This behaviour arises from thermally induced shear stresses between the laminates. For carbon fibre reinforced polymers (CRPs) with different fibre angles the influences of thermal cycling, mechanical creep loading and geometrical shape (plates, half-tubes and tubes) on the expansion behaviour has been investigated. The expansion is influenced in a different manner by thermal cycling and mechanical creep loading. The largest effects arise from thermal cycling and mechanical creep loading of CRPs. The geometrical shape of the specimens influences the expansion behaviour remarkably. The expansion of tubes is smaller compared to that of plates. The reason is coupling of radial and azimuthal components existing for cylindrical samples.

  17. [Over projected tip].

    PubMed

    Duron, J-B; Nguyen, P S; Levet, Y; Bardot, J; Aiach, G

    2014-12-01

    Overprojected tip is a pretty usual request not easy to manage. Preop analysis is crucial in order to evaluate tip support and skin thickness and ability to retract. For example, if the skin is very thick and has poor chance to retract, the surgeon should be very careful in the tip projection decreasing to avoid a skin pollybeak deformity. In such cases, he has to analyze the facial proportions, especially other areas projection (radix, dorsum and chin) and think about augmenting them to balance the profile rather than decreasing tip projection. Correction should always be conducted incrementally, starting with weakening the tip support mechanisms and, only if necessary, continue with alar cartilage interruption. This can be performed on many areas (lateral cruras, domes, medial cruras) and with several techniques (resection or interruption+overlapping).

  18. Vertically aligned nanostructure scanning probe microscope tips

    DOEpatents

    Guillorn, Michael A.; Ilic, Bojan; Melechko, Anatoli V.; Merkulov, Vladimir I.; Lowndes, Douglas H.; Simpson, Michael L.

    2006-12-19

    Methods and apparatus are described for cantilever structures that include a vertically aligned nanostructure, especially vertically aligned carbon nanofiber scanning probe microscope tips. An apparatus includes a cantilever structure including a substrate including a cantilever body, that optionally includes a doped layer, and a vertically aligned nanostructure coupled to the cantilever body.

  19. Distributed ultrafast fibre laser

    PubMed Central

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

    2015-01-01

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

  20. Torsion measurement of catheters using polarized light in a single glass fibre.

    PubMed

    Konings, M K; van Leeuwen, T G; Mali, W P; Viergever, M A

    1998-05-01

    Several types of intravascular ultrasound (IVUS) catheters are connected to a motor at their proximal end, in order to let the catheter rotate around its length axis. However, the rotation of the distal axis tip does not follow exactly the rotation of the motor, since the catheter axis is not completely torsion-free and friction forces cause the tip to rotate in a shockwise manner. In the case of the IVUS catheter, continuous information concerning the exact rotation of the crystal is essential for 3D image reconstruction. We developed a simple method of measuring the tip rotation continuously, the TOMCAT method, using only a single optical fibre glued in a fixed position inside the rotating axis of the IVUS catheter, or any rotating axis or catheter in general. Our method does not require external electromagnetic fields or the presence of a non-rotating guiding catheter. The rotation of the distal tip is related to that of the proximal part by transporting polarized light through the fibre. We performed in vitro experiments using various types of optical fibres to test the TOMCAT method, and conclude that using a specific step-index monomode cylinder-symmetrical optical fibre the TOMCAT approach yields accurate results.

  1. Fibre Optic Probes For Ophthalmology

    NASA Astrophysics Data System (ADS)

    Romaniuk, Ryszard S.

    1986-09-01

    One of the most interesting fields of application of optical fibre technology is the medicine. Among other medical disciplines the field of ophthalmology is very interesting for these applications because of optical character of the organ of vision. After some remarks of a general nature, and concerning the needs of modern ophthalmology, we will review here our trials to apply optical fibre devices for the optical surgery, therapy and diagnosis in the ophthalmology. The devices include: optical fibre illuminators for the applications with operational probes (crioprobes, termal probes, a vitrotom etc.) and some of the diagnostic equipment (like Goldman lens etc.), optical fibre gradient microoptics for delivering of a laser beam to the appropriate internal structures of the eyeglobe, optical fibre lacrimaloscope for the screening of the lacrimal ducts and another one for the orbit. A general conception of the multitask fibre optic microprobe fcr ophthalmological applications - operations and diagnosis/1/ - concludes the work.

  2. Tips for labor coaches

    MedlinePlus

    ... some tips for getting prepared. Before the big day arrives Labor coaches should go to childbirth classes ... get through her labor and delivery. When the day arrives You might be at the hospital for ...

  3. Technology Tips: A Potpourri.

    ERIC Educational Resources Information Center

    Cuoco, Albert A.; And Others, Eds.

    1994-01-01

    Contains tips from readers about using technology in the classroom, including notebook computers, classroom sets of calculators, geometry software, LOGO software, publisher discounts, curriculum materials in CD-ROM, and volunteer help in computers and computer networking for schools. (MKR)

  4. Tips for Daily Living

    MedlinePlus

    ... After Stroke Weight Training After Stroke Tips for Improving Fine Motor Skills Functional Tone Management Arm Training Program Constraint-Induced Movement Therapy Emotional & Behavioral Challenges Self-Esteem after Stroke Post-Stroke Mood Disorders One-side ...

  5. Sulphur-doped silica fibres

    SciTech Connect

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

    2003-01-31

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

  6. Ten Tips for Teachers

    ERIC Educational Resources Information Center

    Mahon, Robert Lee

    2005-01-01

    In this article, the author shares some tips for teachers. His tips are as follows: (1) a teacher should forget his or her education; (2) a teacher should forget the theory (3) a teacher should remember that he or she is a translator, not an originator; (4) a teacher should respect his or her students; (5) a teacher should be true to his or her…

  7. Terbium-doped gadolinium oxysulfide (Gd2O2S:Tb) scintillation-based polymer optical fibre sensor for real time monitoring of radiation dose in oncology

    NASA Astrophysics Data System (ADS)

    Lewis, E.; O'Keeffe, S.; Grattan, M.; Hounsell, A.; McCarthy, D.; Woulfe, P.; Cronin, J.; Mihai, L.; Sporea, D.; Santhanam, A.; Agazaryan, N.

    2014-05-01

    A PMMA based plastic optical fibre sensor for use in real time radiotherapy dosimetry is presented. The optical fibre tip is coated with a scintillation material, terbium-doped gadolinium oxysulfide (Gd2O2S:Tb), which fluoresces when exposed to ionising radiation (X-Ray). The emitted visible light signal penetrates the sensor optical fibre and propagates along the transmitting fibre at the end of which it is remotely monitored using a fluorescence spectrometer. The results demonstrate good repeatability, with a maximum percentage error of 0.5% and the response is independent of dose rate.

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  9. Monomode Fibre Optic Interferometric Sensors.

    NASA Astrophysics Data System (ADS)

    Leilabady, P. Akhavan

    Available from UMI in association with The British Library. Optical fibre sensors are playing an increasingly important role in industrial, medical and military application. Not only are conventional electrically based sensors being gradually replaced by their fibre optic analogues, but also fibre optic sensors are being deployed in special applications where electrically based sensors are unsuitable. Their immunity to electromagnetic interference and inherent high measurement resolution give optical fibre sensors an advantage in diverse applications, including the aerospace and power generation industry and in medicine. The theme of this thesis is interferometric techniques for the recovery of measurand induced modulations of the the fibre guided optical beam. Interferometry offers high measurement resolutions, which makes it the preferred choice for optical processing in certain sensor systems. Interferometric techniques developed for the recovery of the optical phase, polarisation ellipticity and polarisation azimuth are described. However, there are a number of problems, such as the very limited operating range and long term stability that hinder practical implementation of interferometric sensors. These problems are addressed and novel optical processing circuitry based on interferometric detection of phase and polarisation state are introduced which facilitates the development of practical all fibre sensors. Our discussions will start by a general overview of the fibre optic sensor technology, Chapter 1, introducing the principle of sensing by light and the three major categories of fibre optic sensors; multimode fibre intensity modulated sensors, monomode fibre phase modulated sensors and birefringent fibre polarisation state modulated sensors. In Chapter 3, the category of sensors based on phase modulation is addressed describing research carried out into developing an all-fibre optic vortex shedding flowmeter, illustrating interferometric techniques for

  10. Speciality optical fibres for astronomy

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  11. Reticulation des fibres lignocellulosiques

    NASA Astrophysics Data System (ADS)

    Landrevy, Christel

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

  12. Evolving Indications for Tips.

    PubMed

    Smith, Mitchell; Durham, Janette

    2016-03-01

    Transjugular intrahepatic portosystemic shunt creation is a well-established therapy for refractory variceal bleeding and refractory ascites in patients who do not tolerate repeated large volume paracentesis. Experience and technical improvements including covered stents have led to improved TIPS outcomes that have encouraged an expanded application. Evidence for other less frequent indications continues to accumulate, including the indications of primary prophylaxis in patients with high-risk acute variceal bleeding, gastric and ectopic variceal bleeding, primary treatment of medically refractory ascites, recurrent refractory ascites following liver transplantation, hepatic hydrothorax, hepatorenal syndrome, Budd-Chiari syndrome, and portal vein thrombosis. Treatment of patients with high-risk acute variceal bleeding with early TIPS and using transjugular intrahepatic portosystemic shunts as a primary therapy rather than large volume paracentesis for refractory ascites would likely be the 2 circumstances that permit expansion in the frequency of TIPS procedures. The remaining populations discussed above are relatively rare. PMID:26997087

  13. Magnet pole tips

    DOEpatents

    Thorn, Craig E.; Chasman, Chellis; Baltz, Anthony J.

    1984-04-24

    An improved magnet which more easily provides a radially increasing magnetic field, as well as reduced fringe field and requires less power for a given field intensity. The subject invention comprises a pair of spaced, opposed magnetic poles which further comprise a pair of pole roots, each having a pole tip attached to its center. The pole tips define the gap between the magnetic poles and at least a portion of each pole tip is separated from its associated pole root. The separation begins at a predetermined distance from the center of the pole root and increases with increasing radial distance while being constant with azimuth within that portion. Magnets in accordance with the subject invention have been found to be particularly advantageous for use in large isochronous cyclotrons.

  14. Magnet pole tips

    DOEpatents

    Thorn, C.E.; Chasman, C.; Baltz, A.J.

    1981-11-19

    An improved magnet more easily provides a radially increasing magnetic field, as well as reduced fringe field and requires less power for a given field intensity. The subject invention comprises a pair of spaced, opposed magnetic poles which further comprise a pair of pole roots, each having a pole tip attached to its center. The pole tips define the gap between the magnetic poles and at least a portion of each pole tip is separated from its associated pole root. The separation begins at a predetermined distance from the center of the pole root and increases with increasing radial distance while being constant with azimuth within that portion. Magnets in accordance with the subject invention have been found to be particularly advantageous for use in large isochronous cyclotrons.

  15. A new solid phase microextraction method using organic ligand in micropipette tip syringe system packed with modified carbon cloth for preconcentration of cadmium in drinking water and blood samples of kidney failure patients.

    PubMed

    Panhwar, Abdul Haleem; Kazi, Tasneem Gul; Afridi, Hassan Imran; Arain, Salma Aslam; Naeemullah; Brahman, Kapil Dev; Arain, Mariam Shahzadi

    2015-03-01

    A simple and efficient miniaturized solid phase microextraction (M-SPμE) in a syringe system was developed for preconcentration of cadmium (Cd) in environmental and biological samples, followed by flame atomic absorption technique. The syringe system contains the micropipette tip packed with activated carbon cloth, coated with modified magnetic nanoparticles of iron oxide Triton X114 (ACC-NPs). Scanning electron microscopy and energy dispersive spectroscopy used for characterization of the size, morphology and elemental composition of ACC-NPs. The sample solution treated with a complexing reagent 8-hydroxyqunilone (8-HQ), and drawn into the syringe, filled with ACC-MNPs and dispensed manually for 2-10 drawing/discharging cycles. The analyte retained on ACC-NPs in micropipette tip-syringe system were then eluted with different volume of 1.5molL(-1) HCl by 1-5 drawing/discharging cycles. The syringe system directly couple with FAAS for analysis. The influence of different variables on the extraction efficiency of Cd, including adsorbent dosage, pH, sample volume, eluent volume and drawing/discharging cycles of syringe system were optimized. At optimized extraction conditions, the method showed good linearity in the range of 5-250μgL(-1), with a limit of detection 0.15μgL(-1). Repeatability of the extraction (%RSD) was <5%, n=5. The validity and accuracy of the method was checked by the certified reference materials. The proposed method was successfully applied for the determination of Cd in different drinking water and biological samples of kidney failure patients and healthy controls. PMID:25498826

  16. A new solid phase microextraction method using organic ligand in micropipette tip syringe system packed with modified carbon cloth for preconcentration of cadmium in drinking water and blood samples of kidney failure patients.

    PubMed

    Panhwar, Abdul Haleem; Kazi, Tasneem Gul; Afridi, Hassan Imran; Arain, Salma Aslam; Naeemullah; Brahman, Kapil Dev; Arain, Mariam Shahzadi

    2015-03-01

    A simple and efficient miniaturized solid phase microextraction (M-SPμE) in a syringe system was developed for preconcentration of cadmium (Cd) in environmental and biological samples, followed by flame atomic absorption technique. The syringe system contains the micropipette tip packed with activated carbon cloth, coated with modified magnetic nanoparticles of iron oxide Triton X114 (ACC-NPs). Scanning electron microscopy and energy dispersive spectroscopy used for characterization of the size, morphology and elemental composition of ACC-NPs. The sample solution treated with a complexing reagent 8-hydroxyqunilone (8-HQ), and drawn into the syringe, filled with ACC-MNPs and dispensed manually for 2-10 drawing/discharging cycles. The analyte retained on ACC-NPs in micropipette tip-syringe system were then eluted with different volume of 1.5molL(-1) HCl by 1-5 drawing/discharging cycles. The syringe system directly couple with FAAS for analysis. The influence of different variables on the extraction efficiency of Cd, including adsorbent dosage, pH, sample volume, eluent volume and drawing/discharging cycles of syringe system were optimized. At optimized extraction conditions, the method showed good linearity in the range of 5-250μgL(-1), with a limit of detection 0.15μgL(-1). Repeatability of the extraction (%RSD) was <5%, n=5. The validity and accuracy of the method was checked by the certified reference materials. The proposed method was successfully applied for the determination of Cd in different drinking water and biological samples of kidney failure patients and healthy controls.

  17. A new solid phase microextraction method using organic ligand in micropipette tip syringe system packed with modified carbon cloth for preconcentration of cadmium in drinking water and blood samples of kidney failure patients

    NASA Astrophysics Data System (ADS)

    Panhwar, Abdul Haleem; Kazi, Tasneem Gul; Afridi, Hassan Imran; Arain, Salma Aslam; Naeemullah; Brahman, Kapil Dev; Arain, Mariam Shahzadi

    2015-03-01

    A simple and efficient miniaturized solid phase microextraction (M-SPμE) in a syringe system was developed for preconcentration of cadmium (Cd) in environmental and biological samples, followed by flame atomic absorption technique. The syringe system contains the micropipette tip packed with activated carbon cloth, coated with modified magnetic nanoparticles of iron oxide Triton X114 (ACC-NPs). Scanning electron microscopy and energy dispersive spectroscopy used for characterization of the size, morphology and elemental composition of ACC-NPs. The sample solution treated with a complexing reagent 8-hydroxyqunilone (8-HQ), and drawn into the syringe, filled with ACC-MNPs and dispensed manually for 2-10 drawing/discharging cycles. The analyte retained on ACC-NPs in micropipette tip-syringe system were then eluted with different volume of 1.5 mol L-1 HCl by 1-5 drawing/discharging cycles. The syringe system directly couple with FAAS for analysis. The influence of different variables on the extraction efficiency of Cd, including adsorbent dosage, pH, sample volume, eluent volume and drawing/discharging cycles of syringe system were optimized. At optimized extraction conditions, the method showed good linearity in the range of 5-250 μg L-1, with a limit of detection 0.15 μg L-1. Repeatability of the extraction (%RSD) was <5%, n = 5. The validity and accuracy of the method was checked by the certified reference materials. The proposed method was successfully applied for the determination of Cd in different drinking water and biological samples of kidney failure patients and healthy controls.

  18. Fibre laser based on tellurium-doped active fibre

    SciTech Connect

    Alyshev, S V; Ryumkin, K E; Shubin, A V; Medvedkov, O I; Dianov, E M; Khopin, V F; Gur'yanov, A N

    2014-02-28

    We have studied the lasing properties of tellurium-doped germanosilicate fibre, identified its gain and excited-state absorption bands, and assessed the effect of cooling to low temperature (77 K) on the bands. The excitation spectrum of the near-IR luminescence in the fibre has been measured. Lasing at 1.55 mm has been demonstrated for the first time in this gain medium at liquidnitrogen temperature and pump wavelengths of 1.064 and 1.085 mm. The measured Raman spectrum of the fibre provides some insight into the structure of the near-IR luminescence centre. (letters)

  19. A facile approach to spinning multifunctional conductive elastomer fibres with nanocarbon fillers

    NASA Astrophysics Data System (ADS)

    Seyedin, Shayan; Razal, Joselito M.; Innis, Peter C.; Wallace, Gordon G.

    2016-03-01

    Electrically conductive elastomeric fibres prepared using a wet-spinning process are promising materials for intelligent textiles, in particular as a strain sensing component of the fabric. However, these fibres, when reinforced with conducting fillers, typically result in a compromise between mechanical and electrical properties and, ultimately, in the strain sensing functionality. Here we investigate the wet-spinning of polyurethane (PU) fibres with a range of conducting fillers such as carbon black (CB), single-walled carbon nanotubes (SWCNTs), and chemically converted graphene. We show that the electrical and mechanical properties of the composite fibres were strongly dependent on the aspect ratio of the filler and the interaction between the filler and the elastomer. The high aspect ratio SWCNT filler resulted in fibres with the highest electrical properties and reinforcement, while the fibres produced from the low aspect ratio CB had the highest stretchability. Furthermore, PU/SWCNT fibres presented the largest sensing range (up to 60% applied strain) and the most consistent and stable cyclic sensing behaviour. This work provides an understanding of the important factors that influence the production of conductive elastomer fibres by wet-spinning, which can be woven or knitted into textiles for the development of wearable strain sensors.

  20. Multiplexed fibre optic sensors for monitoring resin infusion, flow, and cure in composite material processing

    NASA Astrophysics Data System (ADS)

    Chehura, Edmon; Jarzebinska, Renata; Da Costa, Elisabete F. R.; Skordos, Alexandros A.; James, Stephen W.; Partridge, Ivana K.; Tatam, Ralph P.

    2013-04-01

    The infusion, flow and cure of RTM6 resin in a carbon fibre reinforced composite preform have been monitored using a variety of multiplexed fibre optic sensors. Optical fibre Fresnel sensors and tilted fibre Bragg grating (TFBG) sensors were configured to monitor resin infusion/flow in-plane of the component. The results obtained from the different sensors were in good agreement with visual observations. The degree of cure was monitored by Fresnel sensors via a measurement of the refractive index of the resin which was converted to degree of cure using a calibration determined from Differential Scanning Calorimetry. Fibre Bragg grating sensors fabricated in highly linearly birefringent fibre were used to monitor the development of transverse strain during the cure process, revealing through-thickness material shrinkage of about 712 μɛ and residual strain of 223 μɛ. An alternative approach to infusion monitoring, based on an array of multiplexed tapered optical fibre sensors interrogated using optical frequency domain reflectometry, was also investigated in a separate carbon fibre preform that was infused with RTM6 resin.

  1. Periodic Structures in Optical Fibres.

    NASA Astrophysics Data System (ADS)

    Hand, Duncan Paul

    1990-01-01

    Available from UMI in association with The British Library. The work presented in this thesis concerns techniques for the formation of periodic structures in optical fibres. Two different methods of producing such structures are studied in detail. The first of these involves a breakdown mechanism (known as the 'fibre fuse') that permanently damages the core glass in a periodic manner leaving it unable to guide light. The dynamics of this mechanism are studied, with a view to controlling it for the production of interactive grating structures. It is determined that, due to a sharp rise in fibre absorption with temperature, a thermal shock -wave, with a typical thermal gradient of several hundred degrees Kelvin per micron, forms and travels along the fibre, heating the core glass to such an extent that damage occurs. The periodicity of the resultant damage arises from thermal focusing and defocusing of light in the region of this shock-wave. The second method makes use of the photorefractivity observed in certain germanosilicate fibres on exposure to moderate intensity blue light of wavelength ~480nm or UV light ~240nm. A single-mode fibre transmission filter is demonstrated for the first time, produced by exposing a fibre Sagnac loop mirror to 488nm holographic fringes. Average index changes are shown to occur if such fibres are exposed to spatially uniform blue or UV light, indicating that grating formation is by a different mechanism to the local charge separation which occurs in photorefractive crystals. The various characteristics of these average index changes are measured and analysed, with the conclusion that they result from defect centre formation, driven by two photon absorption with blue light, or single photon absorption with UV light. Associated birefringence changes are also measured and are exploited in a hi-bi fibre to periodically perturb the birefringence axes, producing a narrow-line transmission filter.

  2. Health Tips for Adults

    MedlinePlus

    ... Griffin Rodgers, Director of the NIDDK Clinical Trials Current research studies and how you can volunteer Community Outreach and Health Fairs Science-based information and tips for planning an outreach effort or community event For Health Care Professionals Patient and provider resources ...

  3. TIPs for Technology Integration.

    ERIC Educational Resources Information Center

    Mandell, Susan; Sorge, Dennis H.; Russell, James D.

    2002-01-01

    Discusses the role of the teacher in effectively using technology in education based on the Technology Integration Project (TIP). Topics include why use technology; types of computer software; how to select software; software integration strategies; and effectively planning lessons that integrate the chosen software and integration strategy. (LRW)

  4. Tips for Energy Savers.

    ERIC Educational Resources Information Center

    Department of Energy, Washington, DC.

    According to 1986 U.S. Department of Energy data, 48% of our residential energy is used to heat and cool our homes, 16% goes for heating water, 12% is used to refrigerators and freezers, and the remaining 24% goes into lighting, cooking, and running appliances. This booklet contains tips for saving energy, including sections on: (1) draft-proof…

  5. EcoTipping Points

    ERIC Educational Resources Information Center

    Marten, Gerald G.; Matthews, Catherine E.

    2009-01-01

    Contrary to what we often hear and teach, there is good news to be found on the environmental front. Environmental success stories show us not only that sustainability is possible, but also how people have made it happen. We can make these stories and their lessons accessible to students with help from the EcoTipping Points Project, which has…

  6. Kegel Exercise Tips

    MedlinePlus

    ... PDF, 345 KB) Alternate Language URL Español Kegel Exercise Tips Page Content What are Kegel exercises? To do Kegel exercises, you just squeeze your ... help with your bladder control. How do you exercise your pelvic muscles? Find the right muscles. Try ...

  7. Whispering-gallery waves in optical fibres

    SciTech Connect

    Sychugov, V A; Torchigin, V P; Tsvetkov, M Yu

    2002-08-31

    The process of excitation of whispering-gallery waves (WGWs) in optical fibres (microcavities) with the help of a bitapered fibre is analysed. It is shown that useful information on the WGW modes can be obtained from the spectrograms recorded by scanning the exciting-radiation frequency. Based on the geometrical-optic approximation, the longitudinal sizes of the WGW modes are estimated and it is shown that the ultimate diameter of the fibre exists for optical fibres (microcavities) where a mode can be still excited with the help of a bitapered fibre. (fibre optics. optical fibres)

  8. Optical fibre gas detections systems

    NASA Astrophysics Data System (ADS)

    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. Fibers comprised of epitaxially grown single-wall carbon nanotubes, and a method for added catalyst and continuous growth at the tip

    DOEpatents

    Kittrell, W. Carter; Wang, Yuhuang; Kim, Myung Jong; Hauge, Robert H.; Smalley, Richard E.; Marek leg, Irene Morin

    2010-06-01

    The present invention is directed to fibers of epitaxially grown single-wall carbon nanotubes (SWNTs) and methods of making same. Such methods generally comprise the steps of: (a) providing a spun SWNT fiber; (b) cutting the fiber substantially perpendicular to the fiber axis to yield a cut fiber; (c) etching the cut fiber at its end with a plasma to yield an etched cut fiber; (d) depositing metal catalyst on the etched cut fiber end to form a continuous SWNT fiber precursor; and (e) introducing feedstock gases under SWNT growth conditions to grow the continuous SWNT fiber precursor into a continuous SWNT fiber.

  10. Polarisation reflectometry of anisotropic optical fibres

    SciTech Connect

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

    2009-11-30

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

  11. 14. TIP TOP MINE. TAILINGS LOCATED DIRECTLY WEST FROM TIP ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. TIP TOP MINE. TAILINGS LOCATED DIRECTLY WEST FROM TIP TOP HOUSE. ID-31-C-12 WOODEN STRUCTURE IS VISIBLE IN TOP LEFT. CABLES VISIBLE LEFT AND CENTER OF TAILINGS. HOUSE IS JUST OVER APEX OF TAILINGS. CAMERA POINTED EAST. - Florida Mountain Mining Sites, Tip Top Mine, West face Florida Mountain, approximately 150 feet below summit, Silver City, Owyhee County, ID

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

    NASA Astrophysics Data System (ADS)

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

    2012-01-01

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

  13. Determination of fluoroquinolones in bovine milk samples using a pipette-tip SPE step based on multiwalled carbon nanotubes prior to CE separation.

    PubMed

    Springer, Valeria; Jacksén, Johan; Ek, Patrik; Lista, Adriana G; Emmer, Asa

    2014-01-01

    A simple CE-UV method was developed for the simultaneous determination of ciprofloxacin, norfloxacin, and ofloxacin in milk samples. The optimum separation was obtained using a 20 mM ammonium dihydrogenphosphate solution with 2 mM cetyltrimethylammonium bromide at pH 3.0 as the BGE. Satisfactory resolution for structurally very similar analytes, like norfloxacin and ciprofloxacin, was achieved without including any organic solvent. Milk samples were prepared using a simple/extraction procedure based on acidic protein precipitation followed by an SPE step using only 5 mg of multiwalled carbon nanotubes as the sorbent material. The LODs for the three compounds were between 7.5 and 11.6 μg/L and the RSDs for the peak areas were between 2.6 and 4.9%. The complete method was applied to spiked real milk samples with satisfactory recoveries for all analytes (84-106%).

  14. [Carbonization in endovasal laser obliteration by radial light guide with wavelength of 1470 and 970 nm].

    PubMed

    Shaidakov, E V; Ilyukhin, E A; Grigoryan, A G; Bulatov, V L; Rosukhovsky, D A; Shonov, O A

    2015-01-01

    The authors assessed the effect of carbonization and its influence on the parameters of endovasal laser obliteration (EVLO) depending on wavelength of laser radiation (970 and 1470 nm) using a light guide with radial emission. They also analysed the value of drop of radiation power of the light guide after performing EVLO and visually assessed the degree of damage of the glass tip of the radial fibre by means of ultra-close-up photography. The study comprised a total of 20 patients with varicose disease. A total of ten procedures of EVLO were performed in two modes: mode one - W-laser 1470 nm, mode two - H-laser 970 nm, using fibre with radial emission, an automatic retractor of the light guide. It was determined that the median of power loss after EVLO with W-laser amounted to 0.6 W, and that for H-laser - 3.15 W (p=0.002). Ultra-close-up photography showed pronounced damage of the glass tip of the radial light guide while using H-laser and no damages while using the W-laser. It was proved that using laser radiation with wavelength of 970 nm using the light guide with radial emission leads to pronounced carbonization on the surface of the glass tip of the light guide, its damage, a decrease in radiation power and risk of mechanical destruction of the flask. Using the laser with wavelength of 1470 nm with the use of radial light guide did not result in the development of such negative effects, which increases the service life of laser fibre and makes it possible to use it for obliteration of several segments in one patient. PMID:26355929

  15. Phosphate glass fibre scaffolds: Tailoring of the properties and enhancement of the bioactivity through mesoporous glass particles.

    PubMed

    Novajra, G; Boetti, N G; Lousteau, J; Fiorilli, S; Milanese, D; Vitale-Brovarone, C

    2016-10-01

    Novel bone glass fibre scaffolds were developed by thermally bonding phosphate glass fibres belonging to the P2O5-CaO-Na2O-SiO2-MgO-K2O-TiO2 system (TiPS2.5 glass). Scaffolds with fibres of 85 or 110μm diameter were fabricated, showing compressive strength in the range of 2-3.5MPa, comparable to that of the trabecular bone. The effect of different thermal treatments and fibre diameters and length on the final scaffold structure was investigated by means of micro-CT analysis. The change of the sintering time from 30 to 60min led to a decrease in the scaffold overall porosity from 58 to 21vol.% for the 85μm fibre scaffold and from 50 to 40vol.% when increasing the sintering temperature from 490 to 500°C for the 110μm fibre scaffold. The 85μm fibres resulted in an increase of the scaffold overall porosity, increased pore size and lower trabecular thickness; the use of different fibre diameters allowed the fabrication of a scaffold showing a porosity gradient. In order to impart bioactive properties to the scaffold, for the first time in the literature the introduction in these fibre scaffolds of a bioactive phase, a melt-derived bioactive glass (CEL2) powder or spray-dried mesoporous bioactive glass particles (SD-MBG) was investigated. The scaffold bioactivity was assessed through soaking in simulated body fluid. CEL2/glass fibre scaffold did not show promising results due to particle detachment from the fibres during soaking in simulated body fluid. Instead the use of mesoporous bioactive powders showed to be an effective way to impart bioactivity to the scaffold and could be further exploited in the future through the ability of mesoporous particles to act as systems for the controlled release of drugs.

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

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

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

  17. Smoking - tips on how to quit

    MedlinePlus

    ... Smoking cessation - tips on how to quit; Smokeless tobacco - tips on how to quit; Tobacco cessation - tips; Nicotine cessation - tips ... is hard to stop smoking or using smokeless tobacco, but anyone can do it. Know what symptoms ...

  18. Surface chemical changes of atmospheric pressure plasma treated rabbit fibres important for felting process

    NASA Astrophysics Data System (ADS)

    Štěpánová, Vlasta; Slavíček, Pavel; Stupavská, Monika; Jurmanová, Jana; Černák, Mirko

    2015-11-01

    We introduce the atmospheric pressure plasma treatment as a suitable procedure for in-line industrial application of rabbit fibres pre-treatment. Changes of rabbit fibre properties due to the plasma treatment were studied in order to develop new technology of plasma-based treatment before felting. Diffuse Coplanar Surface Barrier Discharge (DCSBD) in ambient air at atmospheric pressure was used for plasma treatment. Scanning electron microscopy was used for determination of the fibres morphology before and after plasma treatment. X-ray photoelectron spectroscopy and attenuated total reflectance-Fourier transform infrared spectroscopy were used for evaluation of reactive groups. The concentration of carbon decreased and conversely the concentration of nitrogen and oxygen increased after plasma treatment. Aging effect of plasma treated fibres was also investigated. Using Washburn method the significant increase of fibres wettability was observed after plasma treatment. New approach of pre-treatment of fibres before felting using plasma was developed. Plasma treatment of fibres at atmospheric pressure can replace the chemical method which consists of application of strong acids on fibres.

  19. Fibre reinforced composites in aircraft construction

    NASA Astrophysics Data System (ADS)

    Soutis, C.

    2005-02-01

    Fibrous composites have found applications in aircraft from the first flight of the Wright Brothers’ Flyer 1, in North Carolina on December 17, 1903, to the plethora of uses now enjoyed by them on both military and civil aircrafts, in addition to more exotic applications on unmanned aerial vehicles (UAVs), space launchers and satellites. Their growing use has risen from their high specific strength and stiffness, when compared to the more conventional materials, and the ability to shape and tailor their structure to produce more aerodynamically efficient structural configurations. In this paper, a review of recent advances using composites in modern aircraft construction is presented and it is argued that fibre reinforced polymers, especially carbon fibre reinforced plastics (CFRP) can and will in the future contribute more than 50% of the structural mass of an aircraft. However, affordability is the key to survival in aerospace manufacturing, whether civil or military, and therefore effort should be devoted to analysis and computational simulation of the manufacturing and assembly process as well as the simulation of the performance of the structure, since they are intimately connected.

  20. Tipping point leadership.

    PubMed

    Kim, W Chan; Mauborgne, Renée

    2003-04-01

    When William Bratton was appointed police commissioner of New York City in 1994, turf wars over jurisdiction and funding were rife and crime was out of control. Yet in less than two years, and without an increase in his budget, Bratton turned New York into the safest large city in the nation. And the NYPD was only the latest of five law-enforcement agencies Bratton had turned around. In each case, he succeeded in record time despite limited resources, a demotivated staff, opposition from powerful vested interests, and an organization wedded to the status quo. Bratton's turnarounds demonstrate what the authors call tipping point leadership. The theory of tipping points hinges on the insight that in any organization, fundamental changes can occur quickly when the beliefs and energies of a critical mass of people create an epidemic movement toward an idea. Bratton begins by overcoming the cognitive hurdles that block organizations from recognizing the need for change. He does this by putting managers face-to-face with operational problems. Next, he manages around limitations on funds, staff, or equipment by concentrating resources on the areas that are most in need of change and that have the biggest payoffs. He meanwhile solves the motivation problem by singling out key influencers--people with disproportionate power due to their connections or persuasive abilities. Finally, he closes off resistance from powerful opponents. Not every CEO has the personality to be a Bill Bratton, but his successes are due to much more than his personality. He relies on a remarkably consistent method that any manager looking to turn around an organization can use to overcome the forces of inertia and reach the tipping point. PMID:12687920

  1. Fibre prestressed composites: A study of the influences of fibre prestressing on the mechanical properties of polymer matrix composites

    NASA Astrophysics Data System (ADS)

    Motahhari, Siamak

    1998-12-01

    Fibre prestressing during the curing of the polymeric resin is applied in some fabrication processes of composite materials such as filament winding and pultrusion processes. The influences of fibre prestressing on certain mechanical properties have been investigated and justified in the present thesis. Epoxy resin with E-glass fibre and carbon fibre were used to manufacture the samples. The samples were made by applying and holding the tension on the fibres on a horizontal tensiometer machine while the resin was being cured. For glass-epoxy and carbon-epoxy samples different prestressing levels from 10 to 100 MPa and 20 to 140 MPa were applied respectively during the curing of the resin. The samples were made at three different curing temperatures. Flexural strength, flexural modulus, and impact strength of the composites were chosen and measured as representative of the mechanical properties. It was shown that in all cases the studied mechanical properties significantly increased when fibre prestressing increased. The increase of the mechanical properties continued up to a certain fibre prestressing level. Beyond that level, however, the mechanical properties declined. The best fibre prestressing level at which the highest mechanical properties were obtained, was shown to be a function of the curing temperature and the constituent materials of the composites. In the second part of this thesis, the effort has been taken to explain the changes of the mechanical properties caused by fibre prestressing. The residual stresses resulting from the fibre prestressing and resin shrinkage were responsible for the changes of the mechanical properties. A new method was developed to measure the residual stresses which were formed in the composite during the curing process. This method was based of the evaluation of the residual strain in the fibres right after the curing process and removal of applied prestress. Using this method, it was indicated that the residual stresses in

  2. Optofluidic realization and retaining of cell–cell contact using an abrupt tapered optical fibre

    PubMed Central

    Xin, Hongbao; Zhang, Yao; Lei, Hongxiang; Li, Yayi; Zhang, Huixian; Li, Baojun

    2013-01-01

    Studies reveal that there exists much interaction and communication between bacterial cells, with parts of these social behaviors depending on cell–cell contacts. The cell–cell contact has proved to be crucial for determining various biochemical processes. However, for cell culture with relatively low cell concentration, it is difficult to precisely control and retain the contact of a small group of cells. Particularly, the retaining of cell–cell contact is difficult when flows occur in the medium. Here, we report an optofluidic method for realization and retaining of Escherichia coli cell–cell contact in a microfluidic channel using an abrupt tapered optical fibre. The contact process is based on launching a 980-nm wavelength laser into the fibre, E. coli cells were trapped onto the fibre tip one after another, retaining cell–cell contact and forming a highly organized cell chain. The formed chains further show the ability as bio-optical waveguides. PMID:23771190

  3. A Micro-Computed Tomography Technique to Study the Quality of Fibre Optics Embedded in Composite Materials

    PubMed Central

    Chiesura, Gabriele; Luyckx, Geert; Voet, Eli; Lammens, Nicolas; Van Paepegem, Wim; Degrieck, Joris; Dierick, Manuel; Van Hoorebeke, Luc; Vanderniepen, Pieter; Sulejmani, Sanne; Sonnenfeld, Camille; Geernaert, Thomas; Berghmans, Francis

    2015-01-01

    Quality of embedment of optical fibre sensors in carbon fibre-reinforced polymers plays an important role in the resultant properties of the composite, as well as for the correct monitoring of the structure. Therefore, availability of a tool able to check the optical fibre sensor-composite interaction becomes essential. High-resolution 3D X-ray Micro-Computed Tomography, or Micro-CT, is a relatively new non-destructive inspection technique which enables investigations of the internal structure of a sample without actually compromising its integrity. In this work the feasibility of inspecting the position, the orientation and, more generally, the quality of the embedment of an optical fibre sensor in a carbon fibre reinforced laminate at unit cell level have been proven. PMID:25961383

  4. A micro-computed tomography technique to study the quality of fibre optics embedded in composite materials.

    PubMed

    Chiesura, Gabriele; Luyckx, Geert; Voet, Eli; Lammens, Nicolas; Van Paepegem, Wim; Degrieck, Joris; Dierick, Manuel; Van Hoorebeke, Luc; Vanderniepen, Pieter; Sulejmani, Sanne; Sonnenfeld, Camille; Geernaert, Thomas; Berghmans, Francis

    2015-01-01

    Quality of embedment of optical fibre sensors in carbon fibre-reinforced polymers plays an important role in the resultant properties of the composite, as well as for the correct monitoring of the structure. Therefore, availability of a tool able to check the optical fibre sensor-composite interaction becomes essential. High-resolution 3D X-ray Micro-Computed Tomography, or Micro-CT, is a relatively new non-destructive inspection technique which enables investigations of the internal structure of a sample without actually compromising its integrity. In this work the feasibility of inspecting the position, the orientation and, more generally, the quality of the embedment of an optical fibre sensor in a carbon fibre reinforced laminate at unit cell level have been proven.

  5. The effect of fibre orientation on a TWCP composite

    NASA Astrophysics Data System (ADS)

    Barnes, Nicholas; Wood, David; Appleby-Thomas, Gareth; Leighs, James; Roberts, Andrew; Hazell, Paul

    2013-06-01

    Multiple authors have shown that orientation can greatly affect the shock profiles seen in composites. Carbon fibre composites are employed in multiple sectors, with their use in the aerospace industry becoming more prevalent. An angle of 20° between the outer surface and the weave direction provides a good compromise between strength and ablation. Using a single stage gas gun with manganin pressure gauges the shock response of both a 90° and 45° layup TWCP composite were investigated up to a particle velocity of c.a. 1 mm μs-1, in both the US-up and pressure-volume plane. Comparisons in terms of shock propagation were also made with previously investigated TWCP orientations of 0° and 20° as well as other carbon fibre based composites from the literature. This allowed a detailed interrogation of the effects of weave orientation in this important TWCP composite to be made.

  6. Moderate-power cw fibre lasers

    SciTech Connect

    Kurkov, Andrei S; Dianov, Evgenii M

    2004-10-31

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

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

  8. LHCb Upgrade: Scintillating Fibre Tracker

    NASA Astrophysics Data System (ADS)

    Tobin, Mark

    2016-07-01

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

  9. Dietary fibre and cardiovascular health.

    PubMed

    Sánchez-Muniz, F J

    2012-01-01

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

  10. Preliminary study: fibre content in pet rabbit diets, crude fibre versus total dietary fibre.

    PubMed

    Molina, J; Martorell, J; Hervera, M; Pérez-Accino, J; Fragua, V; Villaverde, C

    2015-04-01

    Fibre is an important nutrient for rabbit health, and, on commercial pet rabbit packaging, it is labelled as crude fibre (CF). In several species, it is considered that CF is not an accurate representation of the fibre content in feedstuffs. The objective of this study was to compare the CF stated on the label (CFL) with laboratory analysis of CF (CFA) and the analysed content of total dietary fibre (TDF) in different commercial pet rabbit feeds. We selected 15 commercial diets and analysed CF and TDF. A mixed model was used to evaluate differences between CFL, CFA and TDF, and linear regression was performed to study the correlation between CFL and CFA with TDF. CFA and CFL were not significantly different (p = 0.836) in the feeds studied, and both were lower than TDF (p < 0.001). The correlations between TDF and both CFA and CFL were significant (p < 0.001 and p = 0.02, respectively), but the correlation was better with CFA (R = 0.86) than with CFL (R = 0.53). As expected, TDF content was higher than CF content, an average of two times. These results suggest that the CF content in rabbit diets reported on the label is not an appropriate indicator of their total fibre content, although further work with a larger sample size is required to confirm these results.

  11. Portable smartphone optical fibre spectrometer

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

  12. Skeletal muscle fibre types in the dog.

    PubMed Central

    Latorre, R; Gil, F; Vázquez, J M; Moreno, F; Mascarello, F; Ramirez, G

    1993-01-01

    Using a variety of histochemical methods we have investigated the mATPase reaction of skeletal muscle fibres in the dog. Types I, IIA, IIDog (peculiar to the dog) and IIC fibres were identified. The results reveal that the interpretation of the fibre type composition depends on the methods used. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:8226288

  13. Friction and wear of human hair fibres

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  14. Friction and wear of human hair fibres

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  15. Gas only nozzle fuel tip

    DOEpatents

    Bechtel, William Theodore; Fitts, David Orus; DeLeonardo, Guy Wayne

    2002-01-01

    A diffusion flame nozzle gas tip is provided to convert a dual fuel nozzle to a gas only nozzle. The nozzle tip diverts compressor discharge air from the passage feeding the diffusion nozzle air swirl vanes to a region vacated by removal of the dual fuel components, so that the diverted compressor discharge air can flow to and through effusion holes in the end cap plate of the nozzle tip. In a preferred embodiment, the nozzle gas tip defines a cavity for receiving the compressor discharge air from a peripheral passage of the nozzle for flow through the effusion openings defined in the end cap plate.

  16. Gardening Health and Safety Tips

    MedlinePlus

    ... Health History Parent Information Vaccines & Immunizations Healthy Living Gardening Health and Safety Tips Recommend on Facebook Tweet Share Compartir Gardening can be a great way to enjoy the ...

  17. Wideband-tuneable, nanotube mode-locked, fibre laser

    NASA Astrophysics Data System (ADS)

    Wang, F.; Rozhin, A. G.; Scardaci, V.; Sun, Z.; Hennrich, F.; White, I. H.; Milne, W. I.; Ferrari, A. C.

    2008-12-01

    Ultrashort-pulse lasers with spectral tuning capability have widespread applications in fields such as spectroscopy, biomedical research and telecommunications. Mode-locked fibre lasers are convenient and powerful sources of ultrashort pulses, and the inclusion of a broadband saturable absorber as a passive optical switch inside the laser cavity may offer tuneability over a range of wavelengths. Semiconductor saturable absorber mirrors are widely used in fibre lasers, but their operating range is typically limited to a few tens of nanometres, and their fabrication can be challenging in the 1.3-1.5 µm wavelength region used for optical communications. Single-walled carbon nanotubes are excellent saturable absorbers because of their subpicosecond recovery time, low saturation intensity, polarization insensitivity, and mechanical and environmental robustness. Here, we engineer a nanotube-polycarbonate film with a wide bandwidth (>300 nm) around 1.55 µm, and then use it to demonstrate a 2.4 ps Er3+-doped fibre laser that is tuneable from 1,518 to 1,558 nm. In principle, different diameters and chiralities of nanotubes could be combined to enable compact, mode-locked fibre lasers that are tuneable over a much broader range of wavelengths than other systems.

  18. Fibre ring cavity semiconductor laser

    SciTech Connect

    Duraev, V P; Medvedev, S V

    2013-10-31

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

  19. Tips to Prevent Poisonings

    MedlinePlus

    ... local take back programs in your community . Household Chemicals and Carbon Monoxide Always read the label before using a product that may be poisonous. Keep chemical products in their original bottles or containers. Do ...

  20. Stochastic integrated assessment of climate tipping points indicates the need for strict climate policy

    NASA Astrophysics Data System (ADS)

    Lontzek, Thomas S.; Cai, Yongyang; Judd, Kenneth L.; Lenton, Timothy M.

    2015-05-01

    Perhaps the most `dangerous’ aspect of future climate change is the possibility that human activities will push parts of the climate system past tipping points, leading to irreversible impacts. The likelihood of such large-scale singular events is expected to increase with global warming, but is fundamentally uncertain. A key question is how should the uncertainty surrounding tipping events affect climate policy? We address this using a stochastic integrated assessment model, based on the widely used deterministic DICE model. The temperature-dependent likelihood of tipping is calibrated using expert opinions, which we find to be internally consistent. The irreversible impacts of tipping events are assumed to accumulate steadily over time (rather than instantaneously), consistent with scientific understanding. Even with conservative assumptions about the rate and impacts of a stochastic tipping event, today’s optimal carbon tax is increased by ~50%. For a plausibly rapid, high-impact tipping event, today’s optimal carbon tax is increased by >200%. The additional carbon tax to delay climate tipping grows at only about half the rate of the baseline carbon tax. This implies that the effective discount rate for the costs of stochastic climate tipping is much lower than the discount rate for deterministic climate damages. Our results support recent suggestions that the costs of carbon emission used to inform policy are being underestimated, and that uncertain future climate damages should be discounted at a low rate.

  1. The Macro - TIPS Course Package.

    ERIC Educational Resources Information Center

    Heriot-Watt Univ., Edinburgh (Scotland). Esmee Fairbairn Economics Research Centre.

    The TIPS (Teaching Information Processing System) Course Package was designed to be used with the Macro-Games Course Package (SO 011 930) in order to train college students to apply the tools of economic analysis to current problems. TIPS is used to provide feedback and individualized assignments to students, as well as information about the…

  2. Brilliant Writing Tips for Students

    ERIC Educational Resources Information Center

    Copus, Julia

    2010-01-01

    With tips on punctuation, style, grammar and essay structure, this handy guide provides succinct and practical guidance on students most common areas of concern in their written work. Each tip is supplemented by authentic examples of student writing, suggested re-writes, and appropriate self-help exercises. This book contains four parts. Part I:…

  3. Elastic fibres in health and disease.

    PubMed

    Baldwin, Andrew K; Simpson, Andreja; Steer, Ruth; Cain, Stuart A; Kielty, Cay M

    2013-08-20

    Elastic fibres are insoluble components of the extracellular matrix of dynamic connective tissues such as skin, arteries, lungs and ligaments. They are laid down during development, and comprise a cross-linked elastin core within a template of fibrillin-based microfibrils. Their function is to endow tissues with the property of elastic recoil, and they also regulate the bioavailability of transforming growth factor β. Severe heritable elastic fibre diseases are caused by mutations in elastic fibre components; for example, mutations in elastin cause supravalvular aortic stenosis and autosomal dominant cutis laxa, mutations in fibrillin-1 cause Marfan syndrome and Weill-Marchesani syndrome, and mutations in fibulins-4 and -5 cause autosomal recessive cutis laxa. Acquired elastic fibre defects include dermal elastosis, whereas inflammatory damage to fibres contributes to pathologies such as pulmonary emphysema and vascular disease. This review outlines the latest understanding of the composition and assembly of elastic fibres, and describes elastic fibre diseases and current therapeutic approaches.

  4. Rearrangement of 1D conducting nanomaterials towards highly electrically conducting nanocomposite fibres for electronic textiles.

    PubMed

    Han, Joong Tark; Choi, Sua; Jang, Jeong In; Seol, Seung Kwon; Woo, Jong Seok; Jeong, Hee Jin; Jeong, Seung Yol; Baeg, Kang-Jun; Lee, Geon-Woong

    2015-01-01

    Nanocarbon-based conducting fibres have been produced using solution- or dry-spinning techniques. Highly conductive polymer-composite fibres containing large amounts of conducting nanomaterials have not been produced without dispersants, however, because of the severe aggregation of conducting materials in high-concentration colloidal solutions. Here we show that highly conductive (electrical conductivity ~1.5 × 10(5) S m(-1)) polymer-composite fibres containing carbon nanotubes and silver nanowires can be fabricated via a conventional solution-spinning process without any other treatment. Spinning dopes were fabricated by a simple mixing of a polyvinyl alcohol solution in dimethylsulfoxide with a paste of long multi-walled carbon nanotubes dispersed in organic solvents, assisted by quadruple hydrogen-bonding networks and an aqueous silver nanowire dispersion. The high electrical conductivity of the fibre was achieved by rearrangement of silver nanowires towards the fibre skin during coagulation because of the selective favourable interaction between the silver nanowires and coagulation solvents. The prepared conducting fibres provide applications in electronic textiles such as a textile interconnector of light emitting diodes, flexible textile heaters, and touch gloves for capacitive touch sensors. PMID:25792333

  5. Rearrangement of 1D Conducting Nanomaterials towards Highly Electrically Conducting Nanocomposite Fibres for Electronic Textiles

    NASA Astrophysics Data System (ADS)

    Han, Joong Tark; Choi, Sua; Jang, Jeong In; Seol, Seung Kwon; Woo, Jong Seok; Jeong, Hee Jin; Jeong, Seung Yol; Baeg, Kang-Jun; Lee, Geon-Woong

    2015-03-01

    Nanocarbon-based conducting fibres have been produced using solution- or dry-spinning techniques. Highly conductive polymer-composite fibres containing large amounts of conducting nanomaterials have not been produced without dispersants, however, because of the severe aggregation of conducting materials in high-concentration colloidal solutions. Here we show that highly conductive (electrical conductivity ~1.5 × 105 S m-1) polymer-composite fibres containing carbon nanotubes and silver nanowires can be fabricated via a conventional solution-spinning process without any other treatment. Spinning dopes were fabricated by a simple mixing of a polyvinyl alcohol solution in dimethylsulfoxide with a paste of long multi-walled carbon nanotubes dispersed in organic solvents, assisted by quadruple hydrogen-bonding networks and an aqueous silver nanowire dispersion. The high electrical conductivity of the fibre was achieved by rearrangement of silver nanowires towards the fibre skin during coagulation because of the selective favourable interaction between the silver nanowires and coagulation solvents. The prepared conducting fibres provide applications in electronic textiles such as a textile interconnector of light emitting diodes, flexible textile heaters, and touch gloves for capacitive touch sensors.

  6. Rearrangement of 1D Conducting Nanomaterials towards Highly Electrically Conducting Nanocomposite Fibres for Electronic Textiles

    PubMed Central

    Han, Joong Tark; Choi, Sua; Jang, Jeong In; Seol, Seung Kwon; Woo, Jong Seok; Jeong, Hee Jin; Jeong, Seung Yol; Baeg, Kang-Jun; Lee, Geon-Woong

    2015-01-01

    Nanocarbon-based conducting fibres have been produced using solution- or dry-spinning techniques. Highly conductive polymer-composite fibres containing large amounts of conducting nanomaterials have not been produced without dispersants, however, because of the severe aggregation of conducting materials in high-concentration colloidal solutions. Here we show that highly conductive (electrical conductivity ~1.5 × 105 S m−1) polymer-composite fibres containing carbon nanotubes and silver nanowires can be fabricated via a conventional solution-spinning process without any other treatment. Spinning dopes were fabricated by a simple mixing of a polyvinyl alcohol solution in dimethylsulfoxide with a paste of long multi-walled carbon nanotubes dispersed in organic solvents, assisted by quadruple hydrogen-bonding networks and an aqueous silver nanowire dispersion. The high electrical conductivity of the fibre was achieved by rearrangement of silver nanowires towards the fibre skin during coagulation because of the selective favourable interaction between the silver nanowires and coagulation solvents. The prepared conducting fibres provide applications in electronic textiles such as a textile interconnector of light emitting diodes, flexible textile heaters, and touch gloves for capacitive touch sensors. PMID:25792333

  7. A colour-tunable, weavable fibre-shaped polymer light-emitting electrochemical cell

    NASA Astrophysics Data System (ADS)

    Zhang, Zhitao; Guo, Kunping; Li, Yiming; Li, Xueyi; Guan, Guozhen; Li, Houpu; Luo, Yongfeng; Zhao, Fangyuan; Zhang, Qi; Wei, Bin; Pei, Qibing; Peng, Huisheng

    2015-04-01

    The emergence of wearable electronics and optoelectronics requires the development of devices that are not only highly flexible but can also be woven into textiles to offer a truly integrated solution. Here, we report a colour-tunable, weavable fibre-shaped polymer light-emitting electrochemical cell (PLEC). The fibre-shaped PLEC is fabricated using all-solution-based processes that can be scaled up for practical applications. The design has a coaxial structure comprising a modified metal wire cathode and a conducting aligned carbon nanotube sheet anode, with an electroluminescent polymer layer sandwiched between them. The fibre shape offers unique and promising advantages. For example, the luminance is independent of viewing angle, the fibre-shaped PLEC can provide a variety of different and tunable colours, it is lightweight, flexible and wearable, and it can potentially be woven into light-emitting clothes for the creation of smart fabrics.

  8. Advanced Laser Transmission Welding Strategies for Fibre Reinforced Thermoplastics

    NASA Astrophysics Data System (ADS)

    Wippo, V.; Jaeschke, P.; Brueggmann, M.; Suttmann, O.; Overmeyer, L.

    Laser transmission welding can be used to join endless fibre reinforced thermoplastics. The welding temperature is affected by the heat conduction along carbon fibresand depends on the local orientation of the fibres in the weld seam and the laser welding technique itself. In these investigations the heat development during the welding with quasi-static temperature fields, which is a combination of two laser welding techniques, is evaluated and compared to welding with a homogenized intensity distribution. In order to optimize the temperature distribution over the weld seam width for both linear and curved weld seams, different scanning structures have beenadapted. The experiments were conducted with a diode laser emitting at a wavelength of 940 nm and the process was monitored by aninfrared camera. The used thermoplastics consist of laminates based on unidirectional carbon fibre reinforced polyphenylenesulfide. With the developed scanning structures, a near-homogeneous temperature distribution was generated over the width of the weld seam for curved weld seams, which is not possible by welding with a homogenized laser radiation intensity distribution.

  9. Tipping the scales.

    PubMed

    1998-12-01

    In the US, the October 1998 murder of a physician who performed abortions was an outward manifestation of the insidious battle against legal abortion being waged by radical Christian social conservatives seeking to transform the US democracy into a theocracy. This movement has been documented in a publication entitled, "Tipping the Scales: The Christian Right's Legal Crusade Against Choice" produced as a result of a 4-year investigation conducted by The Center for Reproductive Law and Policy. This publication describes how these fundamentalists have used sophisticated legal, lobbying, and communication strategies to further their goals of challenging the separation of church and state, opposing family planning and sexuality education that is not based solely on abstinence, promoting school prayer, and restricting homosexual rights. The movement has resulted in the introduction of more than 300 anti-abortion bills in states, 50 of which have passed in 23 states. Most Christian fundamentalist groups provide free legal representation to abortion clinic terrorists, and some groups solicit women to bring specious malpractice claims against providers. Sophisticated legal tactics are used by these groups to remove the taint of extremism and mask the danger posed to US constitutional principles being posed by "a well-financed and zealous brand of radical lawyers and their supporters." PMID:12294553

  10. At the Tipping Point

    SciTech Connect

    Wiley, H. S.

    2011-02-28

    There comes a time in every field of science when things suddenly change. While it might not be immediately apparent that things are different, a tipping point has occurred. Biology is now at such a point. The reason is the introduction of high-throughput genomics-based technologies. I am not talking about the consequences of the sequencing of the human genome (and every other genome within reach). The change is due to new technologies that generate an enormous amount of data about the molecular composition of cells. These include proteomics, transcriptional profiling by sequencing, and the ability to globally measure microRNAs and post-translational modifications of proteins. These mountains of digital data can be mapped to a common frame of reference: the organism’s genome. With the new high-throughput technologies, we can generate tens of thousands of data points from each sample. Data are now measured in terabytes and the time necessary to analyze data can now require years. Obviously, we can’t wait to interpret the data fully before the next experiment. In fact, we might never be able to even look at all of it, much less understand it. This volume of data requires sophisticated computational and statistical methods for its analysis and is forcing biologists to approach data interpretation as a collaborative venture.

  11. The Study of a Fibre Z-Pinch

    NASA Astrophysics Data System (ADS)

    Klir, Daniel

    2007-03-01

    This thesis presents the results of fibre Z-pinch experiments carried out on the Z-150 device at the CTU in Prague. The generator that was used to drive the experiments consisted of one capacitor of 3e-6 F capacitance. In the case of 20 kV charging voltage, the current was peaking at 80 kA with a 850 ns quarter period. The Z-pinch was formed from carbon fibres of 15 micrometer diameter and 1 cm length. The discharge was observed by a large number of diagnostic tools. This comprehensive set of diagnostics enabled us to describe the gross dynamics of the Z-pinch. It was found out that after the breakdown a low density coronal plasma was formed while the fibre diameter remained almost unchanged. This low density corona was carrying almost all the current of the order of 10 kA. When the current had built up, the implosion of the corona onto the central fibre occurred. The implosion velocity approached the value of 2e5 m/s. When the imploded corona had reached the fibre, the dip in dI/dt, voltage peak up to 10 kV, and XUV pulse of a 10-30 ns width were observed. XUV radiation was emitted from several bright spots which corresponded to the interaction of m=0 instability necks with the dense core. The electron temperature and density were approximately 80 eV and 10e25 per cubic meter, respectively. Although the presence of a fibre did not significantly suppress MHD instabilities, they were not disruptive. After the fibre ablation, i.e. after 500 ns, material evaporated from electrodes started to play a dominant role. The observed plasma column seemed to be MHD unstable and when m=0 instabilities had developed, X-ray pulses were emitted from several hot spots, particularly near the anode. At that time the voltage peak of up to 30 kV was detected.

  12. Electron processing of fibre-reinforced advanced composites

    NASA Astrophysics Data System (ADS)

    Singh, Ajit; Saunders, Chris B.; Barnard, John W.; Lopata, Vince J.; Kremers, Walter; McDougall, Tom E.; Chung, Minda; Tateishi, Miyoko

    1996-08-01

    Advanced composites, such as carbon-fibre-reinforced epoxies, are used in the aircraft, aerospace, sporting goods, and transportation industries. Though thermal curing is the dominant industrial process for advanced composites, electron curing of similar composites containing acrylated epoxy matrices has been demonstrated by our work. The main attraction of electron processing technology over thermal technology is the advantages it offers which include ambient temperature curing, reduced curing times, reduced volatile emissions, better material handling, and reduced costs. Electron curing technology allows for the curing of many types of products, such as complex shaped, those containing different types of fibres, and up to 15 cm thick. Our work has been done principally with the AECL's 10 MeV, 1 kW electron accelerator; we have also done some comparative work with an AECL Gammacell 220. In this paper we briefly review our work on the various aspects of electron curing of advanced composites and their properties.

  13. A photon-driven micromotor can direct nerve fibre growth

    NASA Astrophysics Data System (ADS)

    Wu, Tao; Nieminen, Timo A.; Mohanty, Samarendra; Miotke, Jill; Meyer, Ronald L.; Rubinsztein-Dunlop, Halina; Berns, Michael W.

    2012-01-01

    Axonal path-finding is important in the development of the nervous system, nerve repair and nerve regeneration. The behaviour of the growth cone at the tip of the growing axon determines the direction of axonal growth and migration. We have developed an optical-based system to control the direction of growth of individual axons (nerve fibres) using laser-driven spinning birefringent spheres. One or two optical traps position birefringent beads adjacent to growth cones of cultured goldfish retinal ganglion cell axons. Circularly polarized light with angular momentum causes the trapped bead to spin. This creates a localized microfluidic flow generating an estimated 0.17 pN shear force against the growth cone that turns in response to the shear. The direction of axonal growth can be precisely manipulated by changing the rotation direction and position of this optically driven micromotor. A physical model estimating the shear force density on the axon is described.

  14. Elastic fibres in health and disease.

    PubMed

    Kielty, Cay M

    2006-08-08

    Elastic fibres are a major class of extracellular matrix fibres that are abundant in dynamic connective tissues such as arteries, lungs, skin and ligaments. Their structural role is to endow tissues with elastic recoil and resilience. They also act as an important adhesion template for cells, and they regulate growth factor availability. Mutations in major structural components of elastic fibres, especially elastin, fibrillins and fibulin-5, cause severe, often life-threatening, heritable connective tissue diseases such as Marfan syndrome, supravalvular aortic stenosis and cutis laxa. Elastic-fibre function is also frequently compromised in damaged or aged elastic tissues. The ability to regenerate or engineer elastic fibres and tissues remains a significant challenge, requiring improved understanding of the molecular and cellular basis of elastic-fibre biology and pathology, and ability to regulate the spatiotemporal expression and assembly of its molecular components.

  15. Transjugular Intrahepatic Portosystemic Shunt (TIPS)

    MedlinePlus

    ... ray or ultrasound equipment, a stent, and a balloon-tipped catheter are used. The equipment typically used ... the stent is in the correct position, the balloon is inflated, expanding the stent into place. The ...

  16. Sports Injury Prevention Tip Sheet

    MedlinePlus

    ... Finance Human Resources and Administrative Services Information Technology Marketing and Sales Membership Practice Public Affairs Quality Publishing ... Feedback Recent a a a print email share Facebook Twitter 2016 Sports Injury Prevention Tip Sheet 3/ ...

  17. Search Tips: MedlinePlus

    MedlinePlus

    ... of this page: https://medlineplus.gov/searchtips.html Search Tips To use the sharing features on this page, please enable JavaScript. How do I search MedlinePlus? The search box appears at the top ...

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

    SciTech Connect

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

    2005-04-30

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

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

    NASA Astrophysics Data System (ADS)

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

    2009-11-01

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

  20. Large-scale fibre-array multiplexing

    SciTech Connect

    Cheremiskin, I V; Chekhlova, T K

    2001-05-31

    The possibility of creating a fibre multiplexer/demultiplexer with large-scale multiplexing without any basic restrictions on the number of channels and the spectral spacing between them is shown. The operating capacity of a fibre multiplexer based on a four-fibre array ensuring a spectral spacing of 0.7 pm ({approx} 10 GHz) between channels is demonstrated. (laser applications and other topics in quantum electronics)

  1. A microfiber coupler tip thermometer.

    PubMed

    Ding, Ming; Wang, Pengfei; Brambilla, Gilberto

    2012-02-27

    A compact thermometer based on a broadband microfiber coupler tip is demonstrated. This sensor can measure a broad temperature interval ranging from room temperature to 1283 °C with sub-200 µm spatial resolution. An average sensitivity of 11.96 pm/°C was achieved for a coupler tip with ~2.5 µm diameter. This is the highest temperature measured with a silica optical fiber device.

  2. Early results of pulsed dye laser angioplasty with integral ball-tips in long femoral occlusions

    NASA Astrophysics Data System (ADS)

    Murray, Alan; Mitchell, David C.; Wood, Richard F. M.

    1990-07-01

    A Pulsed Dye laser together with specifically designed integral ball-tipped optical fibres have been used for the primary recanalisation of femoropopliteal vascular disease in 25 limbs of 23 patients. All patients had complete occlusions of the vessels ranging from 8-49cms in length (mean 22cms), having presented with critical ischaemia (18) or severe claudication warranting operative intervention (5). Pedal ulceration was present in 8 limbs and digital gangrene in 4. The laser produced visible light at 480nm in lOOmJ/lus pulses, at a frequency of 10-20Hz. The energy delivery device comprised a smooth atraumatic ball-tip constructed from the glass of the optical fibre, which was loaded retrogradely into a standard balloon angioplasty catheter. The device was introduced through a common femoral artery cutdown. Angiographic recanalisation was achieved in 22 of the 25 limbs with a mean energy of 280J(range 68-727J) and in each case the channel created by the laser fibre was augmented by balloon angioplasty. Technical failure occurred in three cases, caused by a wall dissection, persistent side-branch entry and incomplete lesion penetration respectively. Eighteen of procedures (72%) were clinically successful with marked symptomatic improvement. Of the four angiographic successful but clinical failures, acute occlusion within 48 hours occurred in 2 diabetic patients with very poor run-off and distal gangrene. The third case failed acutely due to a technically inadequate balloon dilatation and the fourth patient failed to improve symptomatically due to widespread with segmental tibial vessel disease below a successful recanalisation. Over a mean follow-up period of 7 months, three patients died of myocardial infarction. Twelve of the 23 patients (52%) remain well with patent vessels. These early results demonstrate the efficacy of pulsed dye laser angioplasty using ball-tipped optical fibres.

  3. Towards the Knittability of Graphene Oxide Fibres.

    PubMed

    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.

  4. Towards the Knittability of Graphene Oxide Fibres

    PubMed Central

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

    2015-01-01

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

  5. Local dynamics for fibred holomorphic transformations

    NASA Astrophysics Data System (ADS)

    Ponce, Mario

    2007-12-01

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

  6. Thermal response of tellurite glass optical fibre

    NASA Astrophysics Data System (ADS)

    Li, Hongxia; Lousteau, Joris; Bookey, Henry T.; MacPherson, William N.; Barton, James S.; Kar, Ajoy K.; Jha, Animesh

    2007-07-01

    We have measured the phase sensitivity to temperature of a fibre Fabry-Perot (FFP) formed by splicing multimode tellurite (TeO II) glass fibre to singlemode silica fibre. The free spectral ranges of two FFPs of different lengths were consistent with the values expected from independent determinations of the core refractive indices. The phase sensitivity was 89.3 +/- 0.3rad m -1 K -1 at a central wavelength of 1536 nm, compared with 99.8 rad m -1 K -1 for silica fibre.

  7. Towards the Knittability of Graphene Oxide Fibres

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  8. A compact polymer optical fibre ultrasound detector

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

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

    SciTech Connect

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

    2015-05-22

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  11. Characterisation of a fibre optic Raman probe within a hypodermic needle.

    PubMed

    Iping Petterson, Ingeborg E; Day, John C C; Fullwood, Leanne M; Gardner, Benjamin; Stone, Nick

    2015-11-01

    We demonstrate the first use of a multifibre Raman probe that fits inside the bore of a hypodermic needle. A Raman probe containing multiple collection fibres provides improved signal collection efficiency in biological samples compared with a previous two-fibre design. Furthermore, probe performance (signal-to-noise ratios) compared favourably with the performance achieved in previous Raman microscope experiments able to distinguish between benign lymph nodes, primary malignancies in lymph nodes and secondary malignancies in lymph nodes. The experimental measurements presented here give an indication of the sampling volume of the Raman needle probe in lymphoid tissues. Liquid tissue phantoms were used that contained scattering medium encompassing a range of scattering properties similar to those of a variety of tissue types, including lymph node tissues. To validate the appropriateness of the phantoms, the sampling depth of the probe was also measured in excised lymph node tissue. More than 50 % of Raman photons collected were found to originate from between the tip of the needle and a depth of 500 μm into the tissue. The needle probe presented here achieves spectral quality comparable to that in numerous studies previously demonstrating Raman disease discrimination. It is expected that this approach could achieve targeted subcutaneous tissue measurements and be viable for use for the in vivo Raman diagnostics of solid organs located within a few centimetres below the skin's surface. Graphical Abstract Schematic of multi-fibre Raman needle probe with disposible tips and proximal optical filtration. PMID:26416020

  12. Why intra-epidermal electrical stimulation achieves stimulation of small fibres selectively: a simulation study

    NASA Astrophysics Data System (ADS)

    Motogi, Jun; Sugiyama, Yukiya; Laakso, Ilkka; Hirata, Akimasa; Inui, Koji; Tamura, Manabu; Muragaki, Yoshihiro

    2016-06-01

    The in situ electric field in the peripheral nerve of the skin is investigated to discuss the selective stimulation of nerve fibres. Coaxial planar electrodes with and without intra-epidermal needle tip were considered as electrodes of a stimulator. From electromagnetic analysis, the tip depth of the intra-epidermal electrode should be larger than the thickness of the stratum corneum, the electrical conductivity of which is much lower than the remaining tissue. The effect of different radii of the outer ring electrode on the in situ electric field is marginal. The minimum threshold in situ electric field (rheobase) for free nerve endings is estimated to be 6.3 kV m-1. The possible volume for electrostimulation, which can be obtained from the in situ electric field distribution, becomes deeper and narrower with increasing needle depth, suggesting that possible stimulation sites may be controlled by changing the needle depth. The injection current amplitude should be adjusted when changing the needle depth because the peak field strength also changes. This study shows that intra-epidermal electrical stimulation can achieve stimulation of small fibres selectively, because Aβ-, Aδ-, and C-fibre terminals are located at different depths in the skin.

  13. Loss of power output and laser fibre degradation during 120 watt lithium-triborate HPS laser vaporisation of the prostate

    NASA Astrophysics Data System (ADS)

    Hermanns, Thomas; Sulser, Tullio; Hefermehl, Lukas J.; Strebel, Daniel; Michel, Maurice-Stephan; Müntener, Michael; Meier, Alexander H.; Seifert, Hans-Helge

    2009-02-01

    It has recently been shown that laser fibre deterioration leads to a significant decrease of power output during 80 W potassium titanyl phosphate (KTP) laser vaporisation (LV) of the prostate. This decrease results in inefficient vaporisation especially towards the end of the procedure. For the new 120 W lithium-triborate (LBO) High Performance System (HPS) laser not only higher power but also changes in beam characteristics and improved fibre quality have been advertised. However, high laser power has been identified as a risk factor for laser fibre degradation. Between July and September 2008 25 laser fibres were investigated during routine 120 W LBO-LV in 20 consecutive patients. Laser beam power was measured at baseline and after the application of every 25 kJ during the LV procedure. Postoperatively, the surgeon subjectively rated the performance of the respective fibre on a scale from 1 to 4 (1 indicating perfect and 4 insufficient performance). Additionally, microscopic examination of the fibre tip was performed. Median energy applied was 212 kJ. Changes of power output were similar for all fibres. Typically, a steep decrease of power output within the first 50 kJ was followed by a continuous mild decrease until the end of the procedure. After the application of 50 kJ the median power output was 63% (58-73% interquartile range) of the baseline value. The median power output at the end of the 275 kJ-lifespan of the fibres was 42% (40-47%). The median surgeons' rating of the overall performance of the laser fibres was 2 and the median estimated final decrease of power output 60%. Some degree of degradation at the emission window was microscopically detectable in all cases after the procedure. However, even after the application of 275 kJ, these structural changes were only moderate. Minor degradation of the laser fibre was associated with a significant decrease of power output during 120 W LBO-LV. However, following an early, steep decrease, power output

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

    SciTech Connect

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

    2013-12-15

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

  15. Control of interfaces in Al-C fibre composites

    NASA Technical Reports Server (NTRS)

    Warrier, S. G.; Blue, C. A.; Lin, R. Y.

    1993-01-01

    The interface of Al-C fiber composite was modified by coating a silver layer on the surface of carbon fibres prior to making composites, in an attempt to improve the wettability between molten aluminum and carbon fibers during infiltration. An electroless plating technique was adopted and perfected to provide a homogeneous silver coating on the carbon fiber surface. Al-C fiber composites were prepared using a liquid infiltration technique in a vacuum. It was found that silver coating promoted the wetting between aluminum and carbon fibers, particularly with polyacrylonitrile-base carbon fibers. However, due to rapid dissolution of silver in molten aluminum, it was believed that the improved infiltration was not due to the wetting behavior between molten aluminum and silver. The cleaning of the fiber surface and the preservation of the cleaned carbon surface with silver coating was considered to be the prime reason for the improved wettability. Interfacial reactions between aluminum and carbon fibers were observed. Amorphous carbon was found to react more with aluminum than graphitic carbon. This is believed to be because of the inertness of the graphitic basal planes.

  16. Large-sized tubular graphite cones with nanotube tips

    SciTech Connect

    Shang, N.G.; Jiang, X.

    2005-10-17

    Tubular graphite cones (TGCs) have been grown on planar steel substrates by microwave plasma-assisted chemical vapor deposition with a high concentration of methane and at a high substrate temperature. The largest TGCs can reach 110 {mu}m in length and 10 {mu}m in diameter at the root. Unique TGCs terminated in long extruding carbon nanotube tips are realized. Scanning micro-Raman spectroscopy of individual TGCs shows a high crystallinity of the tips and more disordered structure of the roots. A possible growth mechanism of TGCs is presented.

  17. Shape memory polymeric composites sensing by optic fibre Bragg gratings: A very first approach

    NASA Astrophysics Data System (ADS)

    Quadrini, Fabrizio; Santo, Loredana; Ciminello, Monica; Concilio, Antonio; Volponi, Ruggero; Spena, Paola

    2016-05-01

    Shape memory polymer composites (SMPCs) have the potential for many applications in aerospace, spanning from self-repairing of structures to self-deploying of antennas, solar sails, or functional devices (e.g. for grabbing small space debris). In all these cases, it may be essential to have information about their configuration at different stages of shape recovery. In this study, the strain history of a prepreg carbon fibre system, cured with a shape memory polymer (SMP) interlayer, is monitored through a Fibre Bragg Grating (FBG), a fibre optic sensor device. SMPC has been manufactured by using traditional technologies for aerospace. After manufacturing cylindrical shape samples, an external fibre optic system is added to the composite structure; this system is especially suited for high temperatures which are necessary for SMP recovery and composite softening. Sensor functionality is checked before and after each strain history path. Optic fibre arrangement is optimized to avoid unwanted breakings whereas strains are limited by fibre collapsing, i.e. within nominal 2% of deformation. Dynamic information about shape recovery gives fundamental insights about strain evolution during time as well as its spatial distribution.

  18. Investigating the ablation efficiency of a 1940-nm thulium fibre laser for intraoral surgery.

    PubMed

    Guney, M; Tunc, B; Gulsoy, M

    2014-08-01

    The use of a laser in surgical procedures involving the soft tissues is advantageous due to its sterile and hemostatic nature. Several different lasers are in use for intraoral soft tissue surgery; however, small, efficient, and fibre-coupled lasers are favoured due to the tightly confined nature of the intraoral environment. This study proposes the use of a 1940-nm thulium fibre laser (Tm:fibre laser) for intraoral soft tissue procedures. Its thermal effects when used to make incisions were investigated. This laser was chosen due to its output wavelength, which is absorbed well by water in biological tissues. Lamb tongues were used in the experiments. The laser was coupled to a 600-μm silica fibre and incisions were made in contact mode with a continuous wave. The extent of ablation and coagulation produced were measured at three different speeds, powers, and numbers of passes. The thermal effects of laser power, movement speed, and number of passes on incision depth and ablation efficiency were determined. The Tm:fibre laser is a promising tool for intraoral surgery, with excellent absorption by tissue, good coagulative qualities, and easy to manipulate fibre output. Its use as an incisional tool with very little to no carbonization is shown in this study.

  19. Laser fabrication of gold nanoparticle clustered tips for use in apertureless near-field scanning optical microscopy.

    PubMed

    Park, Kyoung-Duck; Park, Jung Su; Park, Jin-Ho; Ahn, Tae Kyu; Lee, Young Hee; Jeong, Mun Seok

    2014-08-01

    A laser fabrication method was developed to make gold nanoparticle clustered (GNC) tips for apertureless near-field scanning optical microscopes (ANSOMs) and tip-enhanced Raman spectroscopy (TERS). The near-field Rayleigh and Raman scattering of samples are highly enhanced when a gold nanoparticle cluster is synthesized on the end of the tip. This is due to the lightning rod effect in the sharp tips. The localized electromagnetic field enhancement and the spatial resolution (~30 nm) of the fabricated GNC tip were verified by TERS and ANSOM measurements of carbon nanotubes. PMID:25936036

  20. Adsorption of dyes by ACs prepared from waste tyre reinforcing fibre. Effect of texture, surface chemistry and pH.

    PubMed

    Acevedo, Beatriz; Rocha, Raquel P; Pereira, Manuel F R; Figueiredo, José L; Barriocanal, Carmen

    2015-12-01

    This paper compares the importance of the texture and surface chemistry of waste tyre activated carbons in the adsorption of commercial dyes. The adsorption of two commercial dyes, Basic Astrazon Yellow 7GLL and Reactive Rifafix Red 3BN on activated carbons made up of reinforcing fibres from tyre waste and low-rank bituminous coal was studied. The surface chemistry of activated carbons was modified by means of HCl-HNO3 treatment in order to increase the number of functional groups. Moreover, the influence of the pH on the process was also studied, this factor being of great importance due to the amphoteric characteristics of activated carbons. The activated carbons made with reinforcing fibre and coal had the highest SBET, but the reinforcing fibre activated carbon samples had the highest mesopore volume. The texture of the activated carbons was not modified upon acid oxidation treatment, unlike their surface chemistry which underwent considerable modification. The activated carbons made with a mixture of reinforcing fibre and coal experienced the largest degree of oxidation, and so had more acid surface groups. The adsorption of reactive dye was governed by the mesoporous volume, whilst surface chemistry played only a secondary role. However, the surface chemistry of the activated carbons and dispersive interactions played a key role in the adsorption of the basic dye. The adsorption of the reactive dye was more favored in a solution of pH 2, whereas the basic dye was adsorbed more easily in a solution of pH 12.

  1. Simulation of complex phenomena in optical fibres

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

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

    SciTech Connect

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

    2012-09-30

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

  3. Turbine blade with contoured chamfered squealer tip

    DOEpatents

    Lee, Ching-Pang

    2014-12-30

    A squealer tip formed from a pressure side tip wall and a suction side tip wall extending radially outward from a tip of the turbine blade is disclosed. The pressure and suction side tip walls may be positioned along the pressure sidewall and the suction sidewall of the turbine blade, respectively. The pressure side tip wall may include a chamfered leading edge with film cooling holes having exhaust outlets positioned therein. An axially extending tip wall may be formed from at least two outer linear surfaces joined together at an intersection forming a concave axially extending tip wall. The axially extending tip wall may include a convex inner surface forming a radially outer end to an inner cavity forming a cooling system. The cooling system may include one or more film cooling holes in the axially extending tip wall proximate to the suction sidewall, which promotes increased cooling at the pressure and suction sidewalls.

  4. Miniature fibre optic probe for minimally invasive photoacoustic sensing

    NASA Astrophysics Data System (ADS)

    Mathews, Sunish J.; Zhang, Edward Z.; Desjardins, Adrien E.; Beard, Paul C.

    2016-03-01

    A miniature (175 μm) all-optical photoacoustic probe has been developed for minimally invasive sensing and imaging applications. The probe comprises a single optical fibre which delivers the excitation light and a broadband 50 MHz Fabry-Pérot (F-P) ultrasound sensor at the distal end for detecting the photoacoustic waves. A graded index lens proximal to the F-P sensor is used to reduce beam walk-off and thus increase sensitivity as well as confine the excitation beam in order to increase lateral spatial resolution. The probe was evaluated in non-scattering media and found to provide lateral and axial resolutions of < 100 μm and < 150 μm respectively for distances up to 1 cm from the tip of the probe. The ability of the probe to detect a blood vessel mimicking phantom at distances up to 7 mm from the tip was demonstrated in order to illustrate its potential suitability for needle guidance applications.

  5. Optical Fibre Technology In Poland

    NASA Astrophysics Data System (ADS)

    Szustakowski, MieczysIaw; Romaniuk, Ryszard S.

    1990-02-01

    The academic and industrial community active in the field of optoelectronics in this country is organizing now every two years a major international meeting on Optical Fibres and their Applications. The first meeting was held in 1976 and the fifth in the series during February 1989. The next meeting is scheduled for February 1991. It used to gather 150 contributed and invited papers and a few hundreds of participants both domestic and international. The proceedings of this meeting are now issued by SPIE-The International Society for Optical Engineering (vols. no 670 and 1085).

  6. Continuum theory of contractile fibres

    NASA Astrophysics Data System (ADS)

    Kruse, K.; Zumdieck, A.; Jülicher, F.

    2003-12-01

    The generation of contractile forces by living cells often involves linear arrangements of actively interacting polar filaments. We develop a physical description of the dynamics of active fibers based on a general expression for the tension in terms of the filament density and the bundle polarisation. We discuss the long-time behaviour of oriented and of nonpolar fibres, discuss effects of polymerization and depolymerization, and relate this continuum theory to nonlocal descriptions of filament-motor systems. We show that a nonpolar arrangement of filaments suppresses oscillatory instabilities which could be relevant for muscle fibers.

  7. Dietary fibre in type II diabetes.

    PubMed

    Asp, N G; Agardh, C D; Ahrén, B; Dencker, I; Johansson, C G; Lundquist, I; Nyman, M; Sartor, G; Scherstén, B

    1981-01-01

    Recent studies have indicated that diets rich in digestible carbohydrates and dietary fibre might be beneficial in the regulation of type II non insulin dependent diabetes (NIDD). Addition of the gel forming type of dietary fibre such as pectin and guar gum to meals or glucose solutions reduces post-prandial glucose and insulin response. Addition of cereal fibres in the form of bran seems to have long term beneficial effect improving glucose tolerance. Little is known, however, concerning effects of dietary fibre naturally occurring in food on postprandial glucose and hormone response. In the present study we prepared two breakfast meals which were similar regarding digestible carbohydrates but differed in their dietary fibre content. One of the meals, including whole grain bread and whole apples, contained 8.4 g of dietary fibre, and the other one, containing white bread and apple juice, 3.1 g. When given to eight NIDD, the fibre rich breakfast gave significantly lower blood glucose increment during the three hours following ingestion. The results indicate that foods rich in dietary fibre might be useful in the regulation of type II diabetes.

  8. SpaceFibre Implementation, Test and Validation

    NASA Astrophysics Data System (ADS)

    Parkes, Steve; McClements, Chris; Ferrer, Albert; Gonzalez Villafranca, Alberto

    2014-08-01

    SpaceFibre is a very high-speed serial data-link being developed by the University of Dundee for the European Space Agency (ESA) which is intended for use in data-handling networks for high data-rate payloads. SpaceFibre is able to operate over fibre-optic and electrical cable and supports data rates of 2 Gbit/s in the near future and up to 5 Gbit/s long-term. It aims to complement the capabilities of the widely used SpaceWire onboard networking standard: improving the data rate by a factor of 12.5, reducing the cable mass and providing galvanic isolation. Multi-laning improves the data-rate further to well over 20 Gbits/s. This paper provides an introduction to SpaceFibre and then describes the work being done by various organisations to simulate, implement, test and validate SpaceFibre.

  9. Self-sensing E-glass fibres

    NASA Astrophysics Data System (ADS)

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

    2003-02-01

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

  10. Erbium-doped aluminophosphosilicate optical fibres

    SciTech Connect

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

    2010-09-10

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

  11. Supercontinuum generation in thulium-doped fibres

    SciTech Connect

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

    2012-09-30

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

  12. Optical cavity fibre sensor for detection of microcystin-LR in water

    NASA Astrophysics Data System (ADS)

    Queirós, Raquel B.; Silva, S. O.; Sales, M. G. F.; Noronha, J. P.; Frazão, O.; Jorge, P. A. S.; Aguilar, G. G.

    2010-09-01

    The deterioration of water quality by Cyanobacteria causes outbreaks and epidemics associated with harmful diseases in Humans and animals because of the released toxins. Microcystin-LR (mcyst) is one of the most widely studied hepatotoxin and World Health Organization recommends a maximum value of 1 μg L-1 of mcyst in drinking-water. Therefore, there is a great demand for remote, real-time sensing techniques to detect and quantify the presence of mcyst. In this work a Fabry-Perot sensing probe based on a fibre tip coated with a mcyst sensitive thin film is presented. Highly specific recognition membranes, using sol-gel based Molecular Imprinted Polymers (MIPs), were developed to quantify microcystins in water, showing great potential in the analysis of this kind of samples. The fibre Fabry-Perot MIP sensor shows a linear response to mcyst concentration with a sensitivity of -13.2 +/-} 0.4 nm L μg-1.

  13. Modelling the nonlinear response of fibre-reinforced bending fluidic actuators

    NASA Astrophysics Data System (ADS)

    Cacucciolo, Vito; Renda, Federico; Poccia, Ernesto; Laschi, Cecilia; Cianchetti, Matteo

    2016-10-01

    Soft actuators are receiving increasing attention from the engineering community, not only in research but even for industrial applications. Among soft actuators, fibre-reinforced bending fluidic actuators (BFAs) became very popular thanks to features such as robustness and easy design and fabrication. However, an accurate modelling of these smart structures, taking into account all the nonlinearities involved, is a challenging task. In this effort, we propose an analytical mechanical model to capture the quasi-static response of fibre-reinforced BFAs. The model is fully 3D and for the first time includes the effect of the pressure on the lateral surface of the chamber as well as the non-constant torque produced by the pressure at the tip. The presented model can be used for design and control, while providing information about the mechanics of these complex actuators.

  14. Root tips moving through soil

    PubMed Central

    Curlango-Rivera, Gilberto

    2011-01-01

    Root elongation occurs by the generation of new cells from meristematic tissue within the apical 1–2 mm region of root tips. Therefore penetration of the soil environment is carried out by newly synthesized plant tissue, whose cells are inherently vulnerable to invasion by pathogens. This conundrum, on its face, would seem to reflect an intolerable risk to the successful establishment of root systems needed for plant life. Yet root tip regions housing the meristematic tissues repeatedly have been found to be free of microbial infection and colonization. Even when spore germination, chemotaxis, and/or growth of pathogens are stimulated by signals from the root tip, the underlying root tissue can escape invasion. Recent insights into the functions of root border cells, and the regulation of their production by transient exposure to external signals, may shed light on long-standing observations. PMID:21455030

  15. Optical fiber meta-tips

    NASA Astrophysics Data System (ADS)

    Principe, Maria; Micco, Alberto; Crescitelli, Alessio; Castaldi, Giuseppe; Consales, Marco; Esposito, Emanuela; La Ferrara, Vera; Galdi, Vincenzo; Cusano, Andrea

    2016-04-01

    We report on the first example of a "meta-tip" configuration that integrates a metasurface on the tip of an optical fiber. Our proposed design is based on an inverted-Babinet plasmonic metasurface obtained by patterning (via focused ion beam) a thin gold film deposited on the tip of an optical fiber, so as to realize an array of rectangular aperture nanoantennas with spatially modulated sizes. By properly tuning the resonances of the aperture nanoantennas, abrupt variations can be impressed in the field wavefront and polarization. We fabricated and characterized several proof-of-principle prototypes operating an near-infrared wavelengths, and implementing the beam-steering (with various angles) of the cross-polarized component, as well as the excitation of surface waves. Our results pave the way to the integration of the exceptional field-manipulation capabilities enabled by metasurfaces with the versatility and ubiquity of fiber-optics technological platforms.

  16. Tipping Points in Texas Rivers

    NASA Astrophysics Data System (ADS)

    Phillips, Jonathan

    2016-04-01

    Anticipating geomorphic tipping points requires that we learn from the past. Major geomorphic changes in coastal plain rivers of Texas resulting in river metamorphosis or regime shifts were identified, and the major driving factors determined. Nine fluvial tipping points were identified from contemporary observations, historical records, and Quaternary reconstructions. Two of the tipping points (between general aggrading and degrading valley states) are associated with reversals in a fundamental system control (sea-level). One (stable or aggrading vs. degrading channels) is associated with an abrupt change in sediment supply due to dam construction, and two others (changes from meandering to anastomosing channel patterns, and different anastomosis styles) are similarly related to changes in sediment supply and/or transport capacity, but with additional elements of historical contingency. Three tipping points are related to avulsions. One, from a regime dominated to reoccupation of former channels to one dominated by progradation into flood basins, is driven by progressive long term filling of incised valleys. Another, nodal avulsions, are driven by disturbances associated with tectonics or listric faults. The third, avulsions and related valley metamorphosis in unfilled incised valleys, is due to fundamental dynamical instabilities within the fluvial system. This synthesis and analysis suggests that geomorphic tipping points are sometimes associated with general extrinsic or intrinsic (to the fluvial system) environmental change, independent of any disturbances or instabilities. Others are associated with natural (e.g., tectonic) or human (dams) disturbances, and still others with intrinsic geomorphic instabilities. This suggests that future tipping points will be equally diverse with respect to their drivers.

  17. Fibre-Matrix Interaction in Soft Tissue

    SciTech Connect

    Guo, Zaoyang

    2010-05-21

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

  18. Highly efficient Raman distributed feedback fibre lasers.

    PubMed

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

    2012-02-27

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

  19. Highly efficient Raman distributed feedback fibre lasers.

    PubMed

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

    2012-02-27

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

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

    PubMed

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

    2016-09-01

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

  1. A Fibre Bragg Grating Sensor as a Receiver for Acoustic Communications Signals

    PubMed Central

    Wild, Graham; Hinckley, Steven

    2011-01-01

    A Fibre Bragg Grating (FBG) acoustic sensor is used as a receiver for acoustic communications signals. Acoustic transmissions were generated in aluminium and Carbon Fibre Composite (CFC) panels. The FBG receiver was coupled to the bottom surface opposite a piezoelectric transmitter. For the CFC, a second FBG was embedded within the layup for comparison. We show the transfer function, frequency response, and transient response of the acoustic communications channels. In addition, the FBG receiver was used to detect Phase Shift Keying (PSK) communications signals, which was shown to be the most robust method in a highly resonant communications channel. PMID:22346585

  2. Influence of double-tip scratch and single-tip scratch on nano-scratching process via molecular dynamics simulation

    NASA Astrophysics Data System (ADS)

    Zhang, Peng; Zhao, Hongwei; Shi, Chengli; Zhang, Lin; Huang, Hu; Ren, Luquan

    2013-09-01

    A three-dimensional molecular dynamics model was proposed to study the influences of scratch feed, depth and crystal orientation on the shape and surface quality of the scratched groove during nano-scratching process. In this paper, comparisons were made between the results of double tips simultaneously scratching the surface and those of single tip successively scratching the surface with the same scratch feed, depth and crystal orientation. EAM potential was used to model the interaction of copper atoms, and Morse potential was used to model the interaction between copper and carbon atoms. The residual profiles of scratched grooves and scratching forces were recorded during the simulations. Simulational results show that when single tip scratches the surface at an extremely small feed, the second time scratch significantly influences the previous groove. The second time scratch has a significant influence on the previous groove by increasing scratch depth. Compared with scratching along crystal orientation [1 0 0], scratching along crystal orientation [0 1 1] and [1 1 1] are easy to obtain two parallel grooves. However, when double tips simultaneously scratch the surface regardless of scratch feed, depth and crystal orientation, two parallel grooves are always obtained. Thus, in order to obtain scratched grooves of high quality, it is quite beneficial to design and machine multiple-tip tools.

  3. Scanning tip microwave near field microscope

    DOEpatents

    Xiang, X.D.; Schultz, P.G.; Wei, T.

    1998-10-13

    A microwave near field microscope has a novel microwave probe structure wherein the probing field of evanescent radiation is emitted from a sharpened metal tip instead of an aperture or gap. This sharpened tip, which is electrically and mechanically connected to a central electrode, extends through and beyond an aperture in an end wall of a microwave resonating device such as a microwave cavity resonator or a microwave stripline resonator. Since the field intensity at the tip increases as the tip sharpens, the total energy which is radiated from the tip and absorbed by the sample increases as the tip sharpens. The result is improved spatial resolution without sacrificing sensitivity. 17 figs.

  4. Scanning tip microwave near field microscope

    DOEpatents

    Xiang, Xiao-Dong; Schultz, Peter G.; Wei, Tao

    1998-01-01

    A microwave near field microscope has a novel microwave probe structure wherein the probing field of evanescent radiation is emitted from a sharpened metal tip instead of an aperture or gap. This sharpened tip, which is electrically and mechanically connected to a central electrode, extends through and beyond an aperture in an endwall of a microwave resonating device such as a microwave cavity resonator or a microwave stripline resonator. Since the field intensity at the tip increases as the tip sharpens, the total energy which is radiated from the tip and absorbed by the sample increases as the tip sharpens. The result is improved spatial resolution without sacrificing sensitivity.

  5. Non-destructive testing on aramid fibres for the long-term assessment of interventions on heritage structures

    NASA Astrophysics Data System (ADS)

    Ceravolo, R.; De Marchi, A.; Pinotti, E.; Surace, C.; Zanotti Fragonara, L.

    2015-07-01

    High strength fibre reinforced polymers (FRPs) are composite materials made of fibres such as carbon, aramid and/or glass, and a resin matrix. FRPs are commonly used for structural repair and strengthening interventions and exhibit high potential for applications to existing constructions, including heritage buildings. In regard to aramid fibres, uncertainties about the long-term behaviour of these materials have often made the designers reluctant to use them in structural engineering. The present study describes simple and non-destructive nonlinearity tests for assessing damage or degradation of structural properties in Kevlar fibres. This was obtained by using high precision measurements to detect small deviations in the dynamic response measured on fibres and ropes. The change in dynamic properties was then related to a damage produced by exposure of the sample to UV rays for a defined time period, which simulated long-term sun exposure. In order to investigate the sensitivity of such an approach to damage detection, non-linearity characterisation tests were conducted on aramid fibres in both damaged and undamaged states. With the purpose of carrying out dynamic tests on small fibre specimens, a dedicated instrumentation was designed and built in cooperation with the Metrology Laboratory of the Department of Electronics at the Politecnico di Torino.

  6. Blade tip timing (BTT) uncertainties

    NASA Astrophysics Data System (ADS)

    Russhard, Pete

    2016-06-01

    Blade Tip Timing (BTT) is an alternative technique for characterising blade vibration in which non-contact timing probes (e.g. capacitance or optical probes), typically mounted on the engine casing (figure 1), and are used to measure the time at which a blade passes each probe. This time is compared with the time at which the blade would have passed the probe if it had been undergoing no vibration. For a number of years the aerospace industry has been sponsoring research into Blade Tip Timing technologies that have been developed as tools to obtain rotor blade tip deflections. These have been successful in demonstrating the potential of the technology, but rarely produced quantitative data, along with a demonstration of a traceable value for measurement uncertainty. BTT technologies have been developed under a cloak of secrecy by the gas turbine OEM's due to the competitive advantages it offered if it could be shown to work. BTT measurements are sensitive to many variables and there is a need to quantify the measurement uncertainty of the complete technology and to define a set of guidelines as to how BTT should be applied to different vehicles. The data shown in figure 2 was developed from US government sponsored program that bought together four different tip timing system and a gas turbine engine test. Comparisons showed that they were just capable of obtaining measurement within a +/-25% uncertainty band when compared to strain gauges even when using the same input data sets.

  7. Library Management Tips that Work

    ERIC Educational Resources Information Center

    Smallwood, Carol, Ed.

    2011-01-01

    There's no shortage of library management books out there--but how many of them actually tackle the little details of day-to-day management, the hard-to-categorize things that slip through the cracks of a larger handbook? "Library Management Tips that Work" does exactly that, addressing dozens of such issues facing library managers, including: (1)…

  8. Turbine blade tip flow discouragers

    SciTech Connect

    Bunker, R.S.

    2000-02-22

    A turbine assembly comprises a plurality of rotating blade portions in a spaced relation with a stationery shroud. The rotating blade portions comprise a root section, a tip portion and an airfoil. The tip portion has a pressure side wall and a suction side wall. A number of flow discouragers are disposed on the blade tip portion. In one embodiment, the flow discouragers extend circumferentially from the pressure side wall to the suction side wall so as to be aligned generally parallel to the direction of rotation. In an alternative embodiment, the flow discouragers extend circumferentially from the pressure side wall to the suction side wall so as to be aligned at an angle in the range between about 0{degree} to about 60{degree} with respect to a reference axis aligned generally parallel to the direction of rotation. The flow discouragers increase the flow resistance and thus reduce the flow of hot gas flow leakage for a given pressure differential across the blade tip portion so as to improve overall turbine efficiency.

  9. Assigning Effective Homework. Classroom Tips

    ERIC Educational Resources Information Center

    American Federation of Teachers (NJ), 2010

    2010-01-01

    Each new school year brings high hopes, great expectations and challenges for both new and seasoned educators. The American Federation of Teachers (AFT) has developed a series called "Classroom Tips" to help educators start the year right and anticipate the year ahead. Over the past 40 years, most research studies on homework have found that…

  10. Teaching Tips: Improving College Instruction.

    ERIC Educational Resources Information Center

    McGlynn, Angela Provitera

    Designed to help teachers improve instruction, this handbook provides tips gathered from focus groups of teachers and students at New Jersey's Mercer County Community College, as well as from other teaching resources. The first part focuses on the contribution of faculty-student interaction to student success, listing 21 suggestions for building…

  11. Turbine blade tip flow discouragers

    DOEpatents

    Bunker, Ronald Scott

    2000-01-01

    A turbine assembly comprises a plurality of rotating blade portions in a spaced relation with a stationery shroud. The rotating blade portions comprise a root section, a tip portion and an airfoil. The tip portion has a pressure side wall and a suction side wall. A number of flow discouragers are disposed on the blade tip portion. In one embodiment, the flow discouragers extend circumferentially from the pressure side wall to the suction side wall so as to be aligned generally parallel to the direction of rotation. In an alternative embodiment, the flow discouragers extend circumferentially from the pressure side wall to the suction side wall so as to be aligned at an angle in the range between about 0.degree. to about 60.degree. with respect to a reference axis aligned generally parallel to the direction of rotation. The flow discouragers increase the flow resistance and thus reduce the flow of hot gas flow leakage for a given pressure differential across the blade tip portion so as to improve overall turbine efficiency.

  12. Evaluation of nasal tip surgery.

    PubMed

    Friedman, W H; Biller, H F

    1975-09-01

    Nasal tip surgery has been evaluated with respect to correction of the lower lateral cartilages. Indications, techniques, results, and complications related to three generic approaches to the lower lateral cartilages are described. In 673 consecutive rhinoplasties the commonest type of nasal tip surgery was excisional, utilizing either a marginal or cartilage splitting technique. These techniques were utilized: 1. to accomplish debulking, and 2. to accomplish the installation of facets. The excisional technique found its greatest utility in primary rhinoplasties. The version technique, utilizing a change of direction of the thrust of the lower lateral cartilages was utilized in a variety of situations, particularly for the correction of moderately congenitally hypoplastic tip cartilages. It also found great utility in surgery of the Negro or cleft palate nose, increasing tip projection, correcting unacceptable bifidity, and in revision rhinoplasty. Augmentation rhinoplasty, utilizing conchal cartilage as an elastic strut was particularly useful for severe hypoplastic cartilage deficits, the Negro nose, columellar retraction, and alar rim deficits. The overall complication rate of lower lateral rhinoplasty was 17.4 percent. The rate of unacceptable complications related to lower lateral rhinoplasty was 2.7 percent.

  13. Top 10 Staff Survival Tips.

    ERIC Educational Resources Information Center

    O'Brien, Laurie

    1995-01-01

    Tips for camp staff on how to survive summer camp include not giving campers sugary drinks before bedtime, setting behavior limits with campers, setting an example by following camp rules, getting enough rest, being fair and consistent, controlling anger, being accountable for actions, asking questions, and being flexible. (LP)

  14. Chalcogenide-tellurite composite microstructured optical fibre

    NASA Astrophysics Data System (ADS)

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

    2012-02-01

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

  15. Small fibre function in primary autonomic failure.

    PubMed

    Baron, R; Feldmann, R; Lindner, V

    1993-12-01

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

  16. Fibre-optic-based fluoroimmunosensors

    SciTech Connect

    Sepaniak, M.J. ); Vodinh, T. )

    1990-01-01

    Remote sensing of chemicals can be performed using fibre optic chemical sensors that use immunochemical reagent phases. Exploiting the specificity of antibody-antigen interactions and the sensitivity of laser-excited fluorimetry, highly selective measurements of ultra-trace levels of chemicals can be performed remotely and in situ via fluoroimmunoassay techniques. In this work, heterogeneous assay protocols using immunobeads are implemented. A passive sensor that samples analyte by diffusion through a permeable membrane and is capable of a single analysis is described and used for the measurement of a naturally fluorescent compound. Subsequently, a regenerable sensor that can perform assay procedures in a repetitive fashion is described and characterized. The versatility of this sensor for performing remote measurements using a variety of established fluorimmunoassay methodologies is discussed.

  17. Characterization of short-fibre reinforced thermoplastics for fracture fixation devices.

    PubMed

    Brown, S A; Hastings, R S; Mason, J J; Moet, A

    1990-10-01

    This study focuses on determining the effects of clinically relevant procedures on the flexural and fracture toughness properties of three short-fibre thermoplastic composites for potential application as fracture fixation devices. The procedures included sterilization, heat contouring and saline soaking. The three materials tested were polysulphone, polybutylene terephthalate and polyetheretherketone, all reinforced with 30% short carbon fibres. The polysulphone composite showed significant degradation in mechanical properties due to saline soaking. The polybutylene terephthalate exhibited significant degradation of mechanical properties following both contouring and saline soaking. The polyetheretherketone composite, however, exhibited no degradation in mechanical properties. The results demonstrated that flexion and fracture toughness testing were effective for determining the response of the composites to different applied conditions and demonstrated the stability of polyetheretherketone subjected to these treatments. Scanning electron microscopy demonstrated the most effective fibre-matrix bonding to be in the polyetheretherketone.

  18. The effect of fibre orientation on a TWCP composite

    NASA Astrophysics Data System (ADS)

    Barnes, N. R.; Hughes, A.; Wood, D. C.; Appleby-Thomas, G. J.; Leighs, J. A.; Goff, M.; Hazell, P. J.

    2014-05-01

    Multiple authors have shown that orientation can greatly affect the shock profiles seen in composites. Carbon fibre composites are employed in multiple sectors, with their use in the aerospace industry becoming more prevalent. An angle of 20° between the outer surface and the weave direction has been shown to provide a good compromise between strength and ablation, making orientation an important property. Using a single stage gas gun with manganin pressure gauges the shock response of both a 90° and 45° layup TWCP composite was investigated up to a particle velocity of approximately 1 mm μs-1, in both the Us-up and pressure-volume planes. Comparisons in terms of shock propagation were also made with a previously investigated TWCP orientation of 0° . This allowed a detailed interrogation of the effects of weave orientation in this important TWCP composite to be made. It was found that the shock response was not greatly altered by orientation of the carbon fibre weave above a certain particle velocity. This was due to the 90° behaving elastically until a particle velocity of 0.6 mm μs-1. Above this value the experimental data had very little deviation regardless of the angle.

  19. Multifunctional and dimensionally stable flexible fibre composites for space applications

    NASA Astrophysics Data System (ADS)

    Datashvili, Leri

    2010-04-01

    Large deployable reflectors typically use knitted metal mesh reflecting surfaces. Knitted metal meshes are characterized by excellent stowability properties. For the operation, meshes have to be tensioned, which leads to much lower accuracy. In order to keep the stowability advantages of knitted meshes but enhancing shape accuracy, a flexible reflecting surface material composed of carbon fibre reinforced silicone (CFRS) has been developed and investigated. Due to its low bending stiffness determined by the silicone matrix, the composite material can be manufactured easily with double curvature and nearly ideal parabolic shape. Compared to the conventional stiff matrix composites, which give high accurate double curved reflecting surfaces, an additional functionality is acquired by using a flexible silicone matrix. The use of this material allows for easy stowing and deployment. Because of the carbon fibres, the CFRS is characterized with a very low thermal expansion coefficient (measured and calculated about -0.36e-6/°C) with no moisture absorption or micro-cracking effects even under strong environmental cycles. These points indicate a high dimensional stability of the material. Results obtained from different thermo-mechanical and radio-frequency (RF) characterization tests for such CFRS surfaces confirm the expected behaviour. The measured RF properties, such as insertion loss, cross-polarization, reflectivity, and passive inter-modulation (PIM), show that the created material can be used even up to 15 GHz of RF. Higher frequencies can be achieved in different cases. Several application examples are addressed further in the paper.

  20. The Effect on the Flexural Strength, Flexural Modulus and Compressive Strength of Fibre Reinforced Acrylic with That of Plain Unfilled Acrylic Resin – An in Vitro Study

    PubMed Central

    Thomas, Tony C; K, Aswini Kumar; Krishnan, Vinod; Mathew, Anil; V, Manju

    2015-01-01

    Aim: The aim of this in vitro study was to compare the flexural strength, the flexural modulus and compressive strength of the acrylic polymer reinforced with glass, carbon, polyethylene and Kevlar fibres with that of plain unfilled resin. Materials and Methods: A total of 50 specimens were prepared and divided into 10 specimens each under 5 groups namely group 1- control group without any fibres, group 2 – carbon fibres, group 3- glass fibres, group 4 – polyethylene, group 5- Kevlar. Universal testing machine (Tinius olsen, USA) was used for the testing of these specimens. Out of each group, 5 specimens were randomly selected and testing was done for flexural strength using a three point deflection test and three point bending test for compressive strength and the modulus was plotted using a graphical method. Statistical analysis was done using statistical software. Results: The respective mean values for samples in regard to their flexural strength for PMMA plain, PMMA+ glass fibre, PMMA+ carbon, PMMA+ polyethylene and PMMA+ Kevlar were 90.64, 100.79, 102.58, 94.13 and 96.43 respectively. Scheffes post hoc test clearly indicated that only mean flexural strength values of PMMA + Carbon, has the highest mean value. One-way ANOVA revealed a non-significant difference among the groups in regard to their compressive strength. Conclusion: The study concludes that carbon fibre reinforced samples has the greatest flexural strength and greatest flexural modulus, however the compressive strength remains unchanged. PMID:25954696

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

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

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

  2. Synchronously pumped picosecond all-fibre Raman laser based on phosphorus-doped silica fibre.

    PubMed

    Kobtsev, Sergey; Kukarin, Sergey; Kokhanovskiy, Alexey

    2015-07-13

    Reported for the first time is picosecond-range pulse generation in an all-fibre Raman laser based on P₂O₅-doped silica fibre. Employment of phosphor-silicate fibre made possible single-cascade spectral transformation of pumping pulses at 1084 nm into 270-ps long Raman laser pulses at 1270 nm. The highest observed fraction of the Stokes component radiation at 1270 nm in the total output of the Raman laser amounted to 30%. The identified optimal duration of the input pulses at which the amount of Stokes component radiation in a ~16-m long phosphorus-based Raman fibre converter reaches its maximum was 140-180 ps.

  3. Tip cap for a rotor blade

    NASA Technical Reports Server (NTRS)

    Kofel, W. K.; Tuley, E. N.; Gay, C. H., Jr.; Troeger, R. E.; Sterman, A. P. (Inventor)

    1983-01-01

    A replaceable tip cap for attachment to the end of a rotor blade is described. The tip cap includes a plurality of walls defining a compartment which, if desired, can be divided into a plurality of subcompartments. The tip cap can include inlet and outlet holes in walls thereof to permit fluid communication of a cooling fluid there through. Abrasive material can be attached with the radially outer wall of the tip cap.

  4. Optical Fibre Pressure Sensors in Medical Applications

    PubMed Central

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

    2015-01-01

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

  5. The Toxicology of Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Donaldson, Ken; Poland, Craig; Duffin, Rodger; Bonner, James

    2012-06-01

    1. Carbon nanotube structure, synthesis and applications C. Singh and W. Song; 2. The aerodynamic behaviour and pulmonary deposition of carbon nanotubes A. Buckley, R. Smith and R Maynard; 3. Utilising the concept of the biologically effective dose to define the particle and fibre hazards of carbon nanotubes K. Donaldson, R. Duffin, F. Murphy and C. Poland; 4. CNT, biopersistence and the fibre paradigm D. Warheit and M. DeLorme; 5. Length-dependent retention of fibres in the pleural space C. Poland, F. Murphy and K. Donaldson; 6. Experimental carcinogenicity of carbon nanotubes in the context of other fibres K. Unfried; 7. Fate and effects of carbon nanotubes following inhalation J. Ryman-Rasmussen, M. Andersen and J. Bonner; 8. Responses to pulmonary exposure to carbon nanotubes V. Castranova and R. Mercer; 9. Genotoxicity of carbon nanotubes R. Schins, C. Albrecht, K. Gerloff and D. van Berlo; 10. Carbon nanotube-cellular interactions; macrophages, epithelial and mesothelial cells V. Stone, M. Boyles, A. Kermanizadeh, J. Varet and H. Johnston; 11. Systemic health effects of carbon nanotubes following inhalation J. McDonald; 12. Dosimetry and metrology of carbon nanotubes L. Tran, L. MacCalman and R. Aitken; Index.

  6. Injector tip for an internal combustion engine

    DOEpatents

    Shyu, Tsu Pin; Ye, Wen

    2003-05-20

    This invention relates to a the tip structure of a fuel injector as used in a internal combustion engine. Internal combustion engines using Homogeneous Charge Compression Ignition (HCCI) technology require a tip structure that directs fuel spray in a downward direction. This requirement necessitates a tip design that is capable of withstanding mechanical stresses associated with the design.

  7. 29 CFR 531.54 - Tip pooling.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Relating to Labor (Continued) WAGE AND HOUR DIVISION, DEPARTMENT OF LABOR REGULATIONS WAGE PAYMENTS UNDER THE FAIR LABOR STANDARDS ACT OF 1938 Interpretations Payment of Wages to Tipped Employees § 531.54 Tip... his tips for purposes of the Act....

  8. 29 CFR 531.54 - Tip pooling.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Relating to Labor (Continued) WAGE AND HOUR DIVISION, DEPARTMENT OF LABOR REGULATIONS WAGE PAYMENTS UNDER THE FAIR LABOR STANDARDS ACT OF 1938 Tipped Employees § 531.54 Tip pooling. Where employees practice... received and retained by each individual as his own are counted as his tips for purposes of the...

  9. 29 CFR 531.54 - Tip pooling.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Relating to Labor (Continued) WAGE AND HOUR DIVISION, DEPARTMENT OF LABOR REGULATIONS WAGE PAYMENTS UNDER THE FAIR LABOR STANDARDS ACT OF 1938 Tipped Employees § 531.54 Tip pooling. Where employees practice... received and retained by each individual as his own are counted as his tips for purposes of the...

  10. 29 CFR 531.54 - Tip pooling.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Relating to Labor (Continued) WAGE AND HOUR DIVISION, DEPARTMENT OF LABOR REGULATIONS WAGE PAYMENTS UNDER THE FAIR LABOR STANDARDS ACT OF 1938 Tipped Employees § 531.54 Tip pooling. Where employees practice... received and retained by each individual as his own are counted as his tips for purposes of the...

  11. 29 CFR 531.54 - Tip pooling.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Relating to Labor (Continued) WAGE AND HOUR DIVISION, DEPARTMENT OF LABOR REGULATIONS WAGE PAYMENTS UNDER THE FAIR LABOR STANDARDS ACT OF 1938 Tipped Employees § 531.54 Tip pooling. Where employees practice... received and retained by each individual as his own are counted as his tips for purposes of the...

  12. Fibre based integral field unit constructional techniques

    NASA Astrophysics Data System (ADS)

    Murray, Graham J.

    2006-06-01

    Presented here is a selected overview of constructional techniques and principles that have been developed and implemented at the University of Durham in the manufacture of successful fibre-based integral field units. The information contained herein is specifically intended to highlight the constructional methods that have been devised to assemble an efficient fibre bundle. Potential pitfalls that need to be considered when embarking upon such a deceptively simple instrument are also discussed.

  13. Fibre Bragg grating for flood embankment monitoring

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  14. Fibre-optic sensors in health care

    NASA Astrophysics Data System (ADS)

    Grazia Mignani, Anna; Baldini, Francesco

    1997-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2009-02-01

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

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

    PubMed

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

    2016-09-01

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

  17. Enhancing the radiation dose detection sensitivity of optical fibres.

    PubMed

    Bradley, D A; Mahdiraji, G Amouzad; Ghomeishi, M; Dermosesian, E; Adikan, F R M; Rashid, H A A; Maah, M J

    2015-06-01

    A method for improving the thermoluminescence (TL) yield of silica-based optical fibres is demonstrated. Using silica obtained from a single manufacturer, three forms of pure (undoped) fibre (capillary-, flat-, and photonic crystal fibre (PCF)) and two forms of Ge-doped fibre (capillary- and flat-fibre) were fabricated. The pure fibre samples were exposed to 6 and 21MeV electrons, the doped fibres to 6MV photons. The consistent observation of large TL yield enhancement is strongly suggestive of surface-strain defects generation. For 6MeV irradiations of flat-fibre and PCF, respective TL yields per unit mass of about 12.0 and 17.5 times that of the undoped capillary-fibre have been observed. Similarly, by making a Ge-doped capillary-fibre into flat-fibre, the TL response is found to increase by some 6.0 times. Thus, in addition to TL from the presence of a dopant, the increase in fused surface areas of flat-fibres and PCF is seen to be a further important source of TL. The glow-curves of the undoped fibres have been analysed by computational deconvolution. Trap centre energies have been estimated and compared for the various fibre samples. Two trap centre types observed in capillary-fibre are also observed in flat-fibre and PCF. An additional trap centre in flat-fibre and one further trap centre in PCF are observed when compared to capillary fibre. These elevated-energy trap centres are linked with strain-generated defects in the collapsed regions of the flat fibre and PCF.

  18. Dewatering of fibre suspensions by pressure filtration

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  19. Criticality and isostaticity in fibre networks

    NASA Astrophysics Data System (ADS)

    Broedersz, Chase P.; Mao, Xiaoming; Lubensky, Tom C.; Mackintosh, Frederick C.

    2011-12-01

    Disordered fibre networks are the basis of many man-made and natural materials, including structural components of living cells and tissue. The mechanical stability of such networks relies on the bending resistance of the fibres, in contrast to rubbers, which are governed by entropic stretching of polymer segments. Although it is known that fibre networks exhibit collective bending deformations, a fundamental understanding of such deformations and their effects on network mechanics has remained elusive. Here we introduce a lattice-based model of fibrous networks with variable connectivity to elucidate the roles of single-fibre elasticity and network structure. These networks exhibit both a low-connectivity rigidity threshold governed by fibre-bending elasticity and a high-connectivity threshold governed by fibre-stretching elasticity. Whereas the former determines the true onset of network rigidity, we show that the latter exhibits rich zero-temperature critical behaviour, including a crossover between various mechanical regimes along with diverging strain fluctuations and a concomitant diverging correlation length.

  20. Fibre intake and prostate cancer risk.

    PubMed

    Pelucchi, Claudio; Talamini, Renato; Galeone, Carlotta; Negri, Eva; Franceschi, Silvia; Dal Maso, Luigino; Montella, Maurizio; Conti, Ettore; La Vecchia, Carlo

    2004-03-20

    Dietary fibre has been reported to protect from several neoplasms, but the issue remains controversial. No previous study considered in depth the topic of fibres and prostate cancer. A multicentre case-control study was conducted in Italy from 1991 to 2002, including 1,294 men with incident, histologically confirmed prostate cancer and 1,451 controls admitted to the same network of hospitals as cases with acute nonmalignant conditions. Multivariate odds ratios (OR) and 95% confidence intervals (CI) were obtained after allowance for major identified confounding factors, including total energy intake. Compared to the lowest quintile, the OR of prostate cancer for the highest quintile of total fibre intake was 0.93 (95% CI 0.71-1.22). The risk was inversely related with soluble fibre (OR = 0.89, 95% CI 0.78-1.02, for a difference between 80th and 20th percentile), cellulose (OR = 0.88, 95% CI 0.78-1.01) and vegetable fibre (OR = 0.82, 95% CI 0.73-0.93). These relationships were consistent across strata of age, family history of prostate cancer, body mass index and education. Vegetable fibres appear, therefore, to have a favourable association with prostate cancer risk. PMID:14750181

  1. Economics Of Optical Fibre Transmission Systems

    NASA Astrophysics Data System (ADS)

    Murray, W. J.

    1983-08-01

    Optical fibre as a telecommunication transmission medium has become one of the most significant developments so far of the digital era. A major contributory factor to the availability of optical fibre transmission systems has been the outstanding progress in the technology of manufacturing high quality glass fibre having relatively low attenuation and broad bandwidths. This and other achievements has enabled manufacturers in the United Kingdom to develop a range of optical fibre cables and transmission equipment for operation over short and long distances at the CCITT recommended digital hierarchical rates of 2, 8, 34 and 140Mbit/s which have been adopted by British Telecom (BT) for modernisation to an all digital transmission network. These optical fibre systems are now becoming increasingly price and performance competitive with conventional technology in many parts of telecommunications networks. In the British Telecom (BT) network the 140Mbit/s optical fibre systems are now economically competitive with equivalent systems on coaxial cable and microwave radio. The economics of 8 and 34Mbit/s systems are not yet sufficiently attractive, compared with 2Mbit/s digital line systems on pair type copper cables, for large scale use in rural and local distribution networks and are presently only justified on cost in and around large cities. As system costs decrease large applications are predicted particularly in support of future high speed data, cable television and visual information services.

  2. Inward spread of activation in frog muscle fibres investigated by means of high-speed microcinematography

    PubMed Central

    Sugi, H.

    1974-01-01

    1. Single fast muscle fibres of the frog were locally activated by applying current pulses to a pipette whose tip was in contact with the fibre surface, and the resulting local contractions were recorded with a high-speed ciné-camera at 1000-3000 frames/sec. 2. In some but not all of the fibres examined, a moderate membrane depolarization of 20-30 mV initiated a phasic type of local contraction, which showed a definite threshold and relaxed spontaneously while the depolarization still continued. 3. The phasic contraction was sometimes followed by a smaller steady contraction, which lasted as long as the depolarization went on and was regarded to be indentical with the graded type of local contraction. 4. With pipettes of 20-40 μm diameter, the phasic contraction was first initiated at the depolarized fibre surface, and spread to some extent inwards with a velocity of 0·7-2 cm/sec at 18-26° C. The velocity of inward spread of contraction had a Q10 of about 2·3. 5. With larger pipettes of more than 50-60 μm diameter, the phasic response was first initiated at the inner part definitely distant from the fibre surface, and the extent of contraction was greater at this part than at the superficial part during the course of the response. Furthermore, with depolarizations of nearly the threshold value, the steady contraction following the phasic one was seen only at the inner part, suggesting the reversal of the gradient of depolarization along the T tubules. 6. The phasic contraction spread inwards or transversely with a considerable decrement. The response spreading across the whole diameter of the fibre could be observed only in some cases. 7. The phasic response was not always sensitive to tetrodotoxin or to the removal of external sodium ions. 8. These results not only give information about the nature of the regenerative mechanism within the T system, but also suggest that the organization of the T tubule network is such that the electrotonic depolarization

  3. Alternating tip splitting in directional solidification.

    PubMed

    Utter, B; Ragnarsson, R; Bodenschatz, E

    2001-05-14

    We report experimental results on the tip splitting dynamics of seaweed growth in directional solidification of succinonitrile alloys. Despite the random appearance of the growth, a tip splitting morphology was observed in which the tip alternately splits to the left and to the right. The tip splitting frequency f was found to be related to the growth velocity V as a power law f~V1.5. This finding is consistent with the predictions of a tip splitting model that is also presented. Small anisotropies are shown to lead to different kinds of seaweed morphologies.

  4. Coated fiber tips for optical instrumentation

    NASA Astrophysics Data System (ADS)

    Barton, John B.; Chanda, Sheetal; Locknar, Sarah A.; Carver, Gary E.

    2016-03-01

    Compact optical systems can be fabricated by integrating coatings on fiber tips. Examples include fiber lasers, fiber interferometers, fiber Raman probes, fiber based spectrometers, and anti-reflected endoscopes. These interference filters are applied to exposed tips - either connectorized or cleaved. Coatings can also be immersed within glass by depositing on one tip and connecting to another uncoated tip. This paper addresses a fiber spectrometer for multispectral imaging - useful in several fields including biomedical scanning, flow cytometry, and remote sensing. Our spectrometer integrates serial arrays of reflecting fiber tips, delay lines between these elements, and a single element detector.

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

    PubMed

    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. PMID:19627797

  6. Parametric tip effects for conformable rotor applications

    NASA Technical Reports Server (NTRS)

    Mantay, W. R.; Yeager, W. T., Jr.

    1983-01-01

    A research study was initiated to systematically determine the impact of selected blade tip geometric parameters on aeroelasticity conformable rotor performance and loads characteristics. The model articulated rotors included baseline and torsionally soft blades with interchangeable tips. Seven blade tip designs were evaluated on the baseline rotor and three tip designs were tested on the torsionally soft blades. The designs incorporated a systematic variation in three geometric parameters: sweep, taper, and anhedral. The rotors were evaluated in the NASA Langley Transonic Dynamics Tunnel at several advance ratios, lift and propulsive force values, and tip Mach numbers. Based on the test results, tip parameter variations generated significant rotor performance and loads difference for both baseline and torsionally soft blades. Azimuthal variation of elastic twist generated by the tip parameters strongly correlated with rotor performance and loads, but the magnitude of advancing blade elastic twist did not correlate.

  7. Advanced turbine blade tip seal system

    NASA Technical Reports Server (NTRS)

    Zelahy, J. W.

    1981-01-01

    An advanced blade/shroud system designed to maintain close clearance between blade tips and turbine shrouds and at the same time, be resistant to environmental effects including high temperature oxidation, hot corrosion, and thermal cycling is described. Increased efficiency and increased blade life are attained by using the advanced blade tip seal system. Features of the system include improved clearance control when blade tips preferentially wear the shrouds and a superior single crystal superalloy tip. The tip design, joint location, characterization of the single crystal tip alloy, the abrasive tip treatment, and the component and engine test are among the factors addressed. Results of wear testing, quality control plans, and the total manufacturing cycle required to fully process the blades are also discussed.

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

    PubMed Central

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

    2013-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Butylina, Svetlana; Martikka, Ossi; Kärki, Timo

    2011-04-01

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

  10. Constitutive modelling of arteries considering fibre recruitment and three-dimensional fibre distribution.

    PubMed

    Weisbecker, Hannah; Unterberger, Michael J; Holzapfel, Gerhard A

    2015-04-01

    Structurally motivated material models may provide increased insights into the underlying mechanics and physics of arteries under physiological loading conditions. We propose a multiscale model for arterial tissue capturing three different scales (i) a single collagen fibre; (ii) bundle of collagen fibres; and (iii) collagen network within the tissue. The waviness of collagen fibres is introduced by a probability density function for the recruitment stretch at which the fibre starts to bear load. The three-dimensional distribution of the collagen fibres is described by an orientation distribution function using the bivariate von Mises distribution, and fitted to experimental data. The strain energy for the tissue is decomposed additively into a part related to the matrix material and a part for the collagen fibres. Volume fractions account for the matrix/fibre constituents. The proposed model only uses two parameters namely a shear modulus of the matrix material and a (stiffness) parameter related to a single collagen fibre. A fit of the multiscale model to representative experimental data obtained from the individual layers of a human thoracic aorta shows that the proposed model is able to adequately capture the nonlinear and anisotropic behaviour of the aortic layers.

  11. Simulation of CNT-AFM tip based on finite element analysis for targeted probe of the biological cell

    NASA Astrophysics Data System (ADS)

    Yousefi, Amin Termeh; Mahmood, Mohamad Rusop; Miyake, Mikio; Ikeda, Shoichiro

    2016-07-01

    Carbon nanotubes (CNTs) are potentially ideal tips for atomic force microscopy (AFM) due to the robust mechanical properties, nano scale diameter and also their ability to be functionalized by chemical and biological components at the tip ends. This contribution develops the idea of using CNTs as an AFM tip in computational analysis of the biological cell's. Finite element analysis employed for each section and displacement of the nodes located in the contact area was monitored by using an output database (ODB). This reliable integration of CNT-AFM tip process provides a new class of high performance nanoprobes for single biological cell analysis.

  12. DC-pulsed voltage electrochemical method based on duty cycle self-control for producing TERS gold tips

    NASA Astrophysics Data System (ADS)

    Vasilchenko, V. E.; Kharintsev, S. S.; Salakhov, M. Kh

    2013-12-01

    This paper presents a modified dc-pulsed low voltage electrochemical method in which a duty cycle is self tuned while etching. A higher yield of gold tips suitable for performing tip-enhanced Raman scattering (TERS) measurements is demonstrated. The improvement is caused by the self-control of the etching rate along the full surface of the tip. A capability of the gold tips to enhance a Raman signal is exemplified by TERS spectroscopy of single walled carbon nanotubes bundle, sulfur and vanadium oxide.

  13. Trends and Tipping Points of Drought-induced Tree Mortality

    NASA Astrophysics Data System (ADS)

    Huang, K.; Yi, C.; Wu, D.; Zhou, T.; Zhao, X.; Blanford, W. J.; Wei, S.; Wu, H.; Du, L.

    2014-12-01

    Drought-induced tree mortality worldwide has been recently reported in a review of the literature by Allen et al. (2010). However, a quantitative relationship between widespread loss of forest from mortality and drought is still a key knowledge gap. Specifically, the field lacks quantitative knowledge of tipping point in trees when coping with water stress, which inhibits the assessments of how climate change affects the forest ecosystem. We investigate the statistical relationships for different (seven) conifer species between Ring Width Index (RWI) and Standardized Precipitation Evapotranspiration Index (SPEI), based on 411 chronologies from the International Tree-Ring Data Bank across 11 states of the western United States. We found robust species-specific relationships between RWI and SPEI for all seven conifer species at dry condition. The regression models show that the RWI decreases with SPEI decreasing (drying) and more than 76% variation of tree growth (RWI) can be explained by the drought index (SPEI). However, when soil water is sufficient (i.e., SPEI>SPEIu), soil water is no longer a restrictive factor for tree growth and, therefore, the RWI shows a weak correlation with SPEI. Based on the statistical models, we derived the tipping point of SPEI (SPEItp) where the RWI equals 0, which means the carbon efflux by tree respiration equals carbon influx by tree photosynthesis. When the severity of drought exceeds this tipping point(i.e. SPEIcarbon assimilated by photosynthesis could not suffice the lowest need of trees maintain respiration. The ranges of the tipping points for seven species-specific trees vary between -2.45 and -1.40. The lower value of a tipping point represents the stronger ability to endure drought. The predicted tipping points can be used as reference of tree mortality for assessment of forest mortality risk under climate change.This work was supported by the Fund for

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

    SciTech Connect

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

    2003-08-31

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

  15. Underwater pressure measurement using fibre optic extrinsic Fabry-Perot interferometric (EFPI) sensors

    NASA Astrophysics Data System (ADS)

    Duraibabu, Dinesh Babu; Poeggel, Sven; Lewis, Elfed; Newe, Thomas

    2014-05-01

    A fibre optic extrinsic Fabry Perot Interferometer (EFPI) sensor is developed for monitoring pressure in the underwater and sub-seabed under simulated conditions. The sensor is robust in design and is fabricated entirely from Silica glass. The EFPI is formed at the tip of the fibre, where the single mode is spliced to a 200μm capillary, sealed by a 200μm Multimode, which forms the diaphragm. The diaphragm thickness is reduced by polishing and etching with hydrofluoric (HF) acid to about 2-3μm for a high sensitivity. The thickness of the diaphragm is monitored online during polishing and HF etching. The spectrum of the fibre optic sensor (FOS) is interrogated using a broad band optical light source and an optical spectrometer. The sensitivity of the sensor achieved is 0.6cmH2O, excellent for small depth-changes. Experimental measurements with saturated salt water and chlorophyll pigmentation of different standards were tested, to simulate the sub-sea conditions where a stability of 0.7cmH2O was reached with a drift of less than 10% under the simulated conditions.

  16. Disinfection of the Optical Fibre of a Nd-YAP Laser Used in Dental Care.

    PubMed

    Rochd, T; Calas, P; Laffitte, F

    1999-03-01

    In order to set up a disinfection protocol, the tip of the optical fibre of an Nd-YAP laser, λ=1.34 μm, was contaminated in vitro with: Mycobacterium smegmatis (CIP 7326), Candida albicans (ATCC 2091), Bacillus stearothermophilus (ATCC 7953) or Streptococcus sanguis (ATCC 10556). It was then treated with various biocidal solutions, Septinol(®) V, glutaraldehyde 2%, ethanol 95° and NaOCl 6%, using one of two protocols: 10 s of contact, or 5 s of contact followed by 5 s of wiping. The latter technique proved to be the most effective. Whatever the biocidal solution used, all the bacteria adhering to the fibre were eliminated. The protocol was checked in vivo in the canals of 10 teeth presenting root canal infections. No bacteria withstood the treatment with Septinol(®) V. This treatment does not alter the qualities and performance of the fibre as far as light transmission is concerned. PMID:24584815

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

    PubMed Central

    Ishizuka, Hisao

    2012-01-01

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

  18. Comparison of Various Supersonic Turbine Tip Designs to Minimize Aerodynamic Loss and Tip Heating

    NASA Technical Reports Server (NTRS)

    Shyam, Vikram; Ameri, Ali

    2012-01-01

    The rotor tips of axial turbines experience high heat flux and are the cause of aerodynamic losses due to tip clearance flows, and in the case of supersonic tips, shocks. As stage loadings increase, the flow in the tip gap approaches and exceeds sonic conditions. This introduces effects such as shock-boundary layer interactions and choked flow that are not observed for subsonic tip flows that have been studied extensively in literature. This work simulates the tip clearance flow for a flat tip, a diverging tip gap and several contoured tips to assess the possibility of minimizing tip heat flux while maintaining a constant massflow from the pressure side to the suction side of the rotor, through the tip clearance. The Computational Fluid Dynamics (CFD) code GlennHT was used for the simulations. Due to the strong favorable pressure gradients the simulations assumed laminar conditions in the tip gap. The nominal tip gap width to height ratio for this study is 6.0. The Reynolds number of the flow is 2.4 x 10(exp 5) based on nominal tip width and exit velocity. A wavy wall design was found to reduce heat flux by 5 percent but suffered from an additional 6 percent in aerodynamic loss coefficient. Conventional tip recesses are found to perform far worse than a flat tip due to severe shock heating. Overall, the baseline flat tip was the second best performer. A diverging converging tip gap with a hole was found to be the best choice. Average tip heat flux was reduced by 37 percent and aerodynamic losses were cut by over 6 percent.

  19. Spun microstructured optical fibres for Faraday effect current sensors

    SciTech Connect

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

    2009-11-30

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

  20. Effect of different lay-ups on the microstructure, mechanical properties and neutron transmission of neutron shielding fibre metal laminates

    NASA Astrophysics Data System (ADS)

    Fu, Xuelong; Tang, Xiaobin; Hu, Yubing; Li, Huaguan; Tao, Jie

    2016-07-01

    A novel neutron shielding fibre metal laminates (NSFMLs) with different lay-ups, composed of stacking layers of AA6061 plates, neutron shielding composite and carbon fibre reinforced polyimide (CFRP), were fabricated using hot molding process in atmospheric environments. The microstructure, mechanical properties and neutron transmission of the NSFMLs were evaluated, respectively. The results indicated that the NSFMLs possessed good mechanical properties owing to the good interfacial adhesion of the components. Tensile strength and elastic modulus of the NSFMLs increased with the numbers of lay-ups, while the elongation to fracture exhibited obvious declining tendency. Flexural strength and modulus of the NSFMLs were improved obviously with the increasing of stacking layers. Neutron transmission of the NSFMLs decreased obviously with increasing the number of lay-ups, owing to the increase of 10B areal density. Besides, the effect of carbon fibres on the neutron shielding performance of the NSFMLs was also taken into consideration.

  1. Automated QuEChERS tips for analysis of pesticide residues in fruits and vegetables by GC-MS.

    PubMed

    Kaewsuya, Pakritsadang; Brewer, William E; Wong, Jon; Morgan, Stephen L

    2013-03-13

    This paper reports the development of an automated method of QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) using pipet tips fitted with filtration screens and containing primary-secondary amine, magnesium sulfate, and graphitized carbon black. These tips are referred to as "QuEChERS Tips". Using loosely contained sorbent, dispersive solid phase extraction (dSPE) cleanup was performed with the QuEChERS Tips and automation. The main advantage of the QuEChERS Tips is that they are readily automated because this dSPE method does not require centrifugation. High recoveries (70-117%) and good reproducibilities (<12%) are shown for over 200 pesticides using automated QuEChERS Tips and GC-MS in various sample matrices.

  2. Force field analysis suggests a lowering of diffusion barriers in atomic manipulation due to presence of STM tip.

    PubMed

    Emmrich, Matthias; Schneiderbauer, Maximilian; Huber, Ferdinand; Weymouth, Alfred J; Okabayashi, Norio; Giessibl, Franz J

    2015-04-10

    We study the physics of atomic manipulation of CO on a Cu(111) surface by combined scanning tunneling microscopy and atomic force microscopy at liquid helium temperatures. In atomic manipulation, an adsorbed atom or molecule is arranged on the surface using the interaction of the adsorbate with substrate and tip. While previous experiments are consistent with a linear superposition model of tip and substrate forces, we find that the force threshold depends on the force field of the tip. Here, we use carbon monoxide front atom identification (COFI) to characterize the tip's force field. Tips that show COFI profiles with an attractive center can manipulate CO in any direction while tips with a repulsive center can only manipulate in certain directions. The force thresholds are independent of bias voltage in a range from 1 to 10 mV and independent of temperature in a range of 4.5 to 7.5 K. PMID:25910137

  3. Force Field Analysis Suggests a Lowering of Diffusion Barriers in Atomic Manipulation Due to Presence of STM Tip

    NASA Astrophysics Data System (ADS)

    Emmrich, Matthias; Schneiderbauer, Maximilian; Huber, Ferdinand; Weymouth, Alfred J.; Okabayashi, Norio; Giessibl, Franz J.

    2015-04-01

    We study the physics of atomic manipulation of CO on a Cu(111) surface by combined scanning tunneling microscopy and atomic force microscopy at liquid helium temperatures. In atomic manipulation, an adsorbed atom or molecule is arranged on the surface using the interaction of the adsorbate with substrate and tip. While previous experiments are consistent with a linear superposition model of tip and substrate forces, we find that the force threshold depends on the force field of the tip. Here, we use carbon monoxide front atom identification (COFI) to characterize the tip's force field. Tips that show COFI profiles with an attractive center can manipulate CO in any direction while tips with a repulsive center can only manipulate in certain directions. The force thresholds are independent of bias voltage in a range from 1 to 10 mV and independent of temperature in a range of 4.5 to 7.5 K.

  4. Endoscopic septoplasty: Tips and pearls.

    PubMed

    Pons, Y; Champagne, C; Genestier, L; Ballivet de Régloix, S

    2015-12-01

    This article is designed to provide a step-by-step description of our endoscopic septoplasty technique and discuss its difficulties and technical tips. Endoscopic septoplasty comprises 10 steps: diagnostic endoscopy, subperichondral infiltration, left mucosal incision, dissection of the left subperichondral flap, cartilage incision (0.5 centimetre posterior to the mucosal incision), dissection of the right subperichondral flap, anterior cartilage resection, perpendicular plate dissection, dissection and resection of the maxillary crest, endoscopic revision, mucosal suture and Silastic stents. A satisfactory postoperative result was observed at 3 months in 97% of cases in this series. The main contraindication to endoscopic septoplasty is anterior columellar deviation of the nasal septum requiring a conventional procedure.

  5. Multiple gamma radiation sterilization of polyester fibres.

    PubMed

    Nair, P D; Sreenivasan, K; Jayabalan, M

    1988-07-01

    Gamma radiation with a dose of 2.5 Mrad has been found to be suitable to sterilize polyethylene terephthalate (PET) bulk materials intended for biomedical applications. The radiation stability of PET bulk materials and fibre may not however be taken as identical due to the changes in the polymer structure during the processing of bulk materials for fibre. The chemical changes occurring in PET fibres during single and multiple (prolonged) sterilization in air were investigated. It was found that single sterilization (2.5 Mrad) itself affected the PET yarn and fibre. This was exhibited by the increase of crystallinity from 30.5 to 37% in the case of yarn and from 40 to 44% in the case of fibre. The breaking load of the yarn also increased from 441 g to 451 g. These changes were attributed to the degradation of PET in the amorphous region and the recombination of degraded aliphatic segments. Sterilization at higher doses affected the crystalline region which decreased the crystallinity, breaking load and molecular weight. For samples irradiated at 2.5 Mrad, the breaking load increased, though the dispersity increased. This was attributed to cross-linking by recombination. The increase in crystallinity also enhanced the breaking load of the samples. Higher doses of sterilization led to drastic microstructural and macrostructural changes as seen from the molecular weight. It was inferred that the changes in crystallinity and microstructure that occurred during multiple sterilization might affect the biocompatibility of the material. PMID:2975186

  6. On singular fibres in F-theory

    NASA Astrophysics Data System (ADS)

    Braun, Andreas P.; Watari, Taizan

    2013-07-01

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

  7. Effectiveness of cigarette filter tips for reducing cadmium in relation to other mainstream smoke constituents

    SciTech Connect

    Bache, C.A.; Lisk, D.J.; Shane, B.S.; Hoffmann, D.; Adams, J.D.

    1987-01-01

    The effectiveness of filter tips for reducing cadmium, tar, nicotine, carbon monoxide and carbon dioxide in cigarettes was studied. The cigarettes were made from tobacco grown on municipal sewage sludge-amended soil and were therefore high in cadmium. When machine-smoked, filter tips did not result in a significant reduction of cadmium deposited on Cambridge filters. This may indicate that a considerable fraction of cadmium is present in the vapor phase of the smoke and therefore not reduced to the same extent as the tar by certain filters. Nicotine and carbon monoxide were reduced to a lesser extent than tar. This indicates that the filter tip has influenced the combustion of the tobacco column during smoking.

  8. Blade Tip Rubbing Stress Prediction

    NASA Technical Reports Server (NTRS)

    Davis, Gary A.; Clough, Ray C.

    1991-01-01

    An analytical model was constructed to predict the magnitude of stresses produced by rubbing a turbine blade against its tip seal. This model used a linearized approach to the problem, after a parametric study, found that the nonlinear effects were of insignificant magnitude. The important input parameters to the model were: the arc through which rubbing occurs, the turbine rotor speed, normal force exerted on the blade, and the rubbing coefficient of friction. Since it is not possible to exactly specify some of these parameters, values were entered into the model which bracket likely values. The form of the forcing function was another variable which was impossible to specify precisely, but the assumption of a half-sine wave with a period equal to the duration of the rub was taken as a realistic assumption. The analytical model predicted resonances between harmonics of the forcing function decomposition and known harmonics of the blade. Thus, it seemed probable that blade tip rubbing could be at least a contributor to the blade-cracking phenomenon. A full-scale, full-speed test conducted on the space shuttle main engine high pressure fuel turbopump Whirligig tester was conducted at speeds between 33,000 and 28,000 RPM to confirm analytical predictions.

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

    NASA Astrophysics Data System (ADS)

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

    2007-10-01

    The International Conference on Optical Fibre Sensors (OFS-18) was held in October 2006 in Cancún, Mexico, under the general chairmanship of Dr Alexis Mendez (MCH Engineering LLC, USA) and Dr Fernando Mendoza (Centro de Investigaciones en Optica, Mexico). 'OFS', as it has become known, is firmly established as the leading international conference for the optical fibre sensor community. Since its inception, in London in 1983, and under the leadership of an international steering committee independent of any learned society or professional institution, it has been held approximately every eighteen months. The venue nominally rotates from Europe, to the Americas, and thence to Asia and the Pacific. OFS-18 demonstrated the continuing vigour of the community, with some 250 papers presented, plus two workshops, with attendance as international as ever. In recent years, it has become a tradition to publish a post-conference special issue in the journal Measurement Science and Technology, and these special issues offer a representative sample of the current status of the field. In the nearly 25 years since OFS began, many of the early ideas and laboratory-based proof-of-principle experiments have led to highly developed instrumentation systems, and to successful commercial products. Perhaps the most mature of all of these technologies is the optical fibre gyroscope, with the fibre hydrophone a close second—originally developed for defence applications for which it is now established, but with increasing relevance to the oil and gas industry; electromagnetic sensors based on the Faraday and electro-optic effects are of growing significance in the power generation and distribution industry; whilst in-fibre grating-based sensors occupy an expanding niche in structural monitoring, especially in civil engineering. It is therefore appropriate that the first day of OFS was devoted to workshops on structural health monitoring, and to commemorate the 30th anniversary of the

  10. Tipping elements in the Earth's climate system

    SciTech Connect

    Lenton, T.M.; Held, H.; Lucht, W.; Rahmstorf, S.; Kriegler, E. |; Hall, J.W.; Schellnhuber, H.J. |

    2008-02-12

    The term 'tipping point' commonly refers to a critical threshold at which a tiny perturbation can qualitatively alter the state or development of a system. Here the authors introduce the term 'tipping element' to describe large-scale components of the Earth system that may pass a tipping point. They critically evaluate potential policy-relevant tipping elements in the climate system under anthropogenic forcing, drawing on the pertinent literature and a recent international workshop to compile a short list, and they assess where their tipping points lie. An expert elicitation is used to help rank their sensitivity to global warming and the uncertainty about the underlying physical mechanisms. Then the authors explain how, in principle, early warning systems could be established to detect the proximity of some tipping points.

  11. On-line monitoring of biofilm formation in a brewery water pipeline system with a fibre optical device.

    PubMed

    Tamachkiarow, L; Flemming, H C

    2003-01-01

    Any advanced anti-fouling strategy must be based on early warning systems which allow for timely, precisely directed and optimized countermeasures. Such systems must be able to detect biofilm growth on representative surfaces. In order to meet this requirement, a fibre optical device (FOS) has been developed. It is based on light which is scattered by objects deposited on the tip of an optical fibre. A receiving fibre collects the signal and forwards it to a detection and quantification unit. Both the sending and the receiving fibre are mounted in a measuring head which is integrated evenly on the inner surface of a water pipeline at representative sites. This device was applied to a water system of a brewery in order toput its reliability to test under practical conditions. The FOS detected the build-up of a deposit which was identified independently as consisting of microorganisms, i.e., a biofilm. A stable, well detectable and reproducible signal could be obtained above a colonization of 10(5) cells cm-2. Adjustment of the sensitivity of the amplifier allowed for detection of biofilms up to 10(10) cells cm-2. Cleaning countermeasures could be detected clearly by a decrease of backscattered light intensity. The system proved to be suitable for on-line, non-destructive, real-time and automatic monitoring for a period of almost two years, and thus, provides an important constituent for an advanced anti-fouling strategy.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  13. Optical fibre cantilever sensor for biological application

    NASA Astrophysics Data System (ADS)

    Li, J.; Zhou, Y. X.; Patterson, G.; Shu, W. M.; Maier, R. R. J.; Fowler, R.; Hand, D. P.; MacPherson, W. N.

    2014-05-01

    Micro-cantilever sensors have shown great promise in a wide range of application are as including chemical and biological sensing. However, many of these devices are based upon a sensor `chip' that requires careful alignment between the cantilever and the read-out system, which can be challenging. Furthermore, optical interrogation typically involves a bulky free-space system. Optical fibre addressed cantilevers have been reported previously in the literature and in this paper we propose techniques to design and fabricate polymer micro-cantilevers for attachment onto the end of standard single mode fibres using laser machining. Low-cost optical sources and a fibre coupled spectrometer are employed to monitor the cantilever deflection and therefore observe biological binding between a species of interest and an activated cantilever. Proof-of-concept experiments show that the sensor is capable of detecting pathogen concentration with down to a level of 105cfu/ml.

  14. Capillary droplet propulsion on a fibre.

    PubMed

    Haefner, Sabrina; Bäumchen, Oliver; Jacobs, Karin

    2015-09-21

    A viscous liquid film coating a fibre becomes unstable and decays into droplets due to the Rayleigh-Plateau instability (RPI). Here, we report on the generation of uniform droplets on a hydrophobized fibre by taking advantage of this effect. In the late stages of liquid column breakup, a three-phase contact line can be formed at one side of the droplet by spontaneous rupture of the thinning film. The resulting capillary imbalance leads to droplet propulsion along the fibre. We study the dynamics and the dewetting speed of the droplet as a function of molecular weight as well as temperature and compare to a force balance model based on purely viscous dissipation.

  15. Multimode fibres for micro-endoscopy

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  16. Porous Materials Reinforced by Statistically Oriented Fibres

    NASA Astrophysics Data System (ADS)

    Federico, Salvatore; Grillo, Alfio

    2010-09-01

    Hydrated soft biological tissues, such as articular cartilage, are well represented by a porous matrix saturated by a fluid and reinforced by a network of statistically oriented, impermeable collagen fibres. A previously developed homogenisation method for porous fibre-reinforced materials with an isotropic matrix, under small deformations, was capable of correctly predicting some specific aspects of the anisotropy and inhomogeneity of the permeability in the tissue. The aim of this work is to generalise this model to the case of large deformations. This is achieved by means of a rescaled pull-back of the structure tensor describing fibre orientation, and directional averaging methods allowing to account for the statistical distribution of the orientation. The resulting permeability tensor contains an integral term that must be implemented numerically, because of the explicit presence of the deformation in the integrand function.

  17. An investigation of counterrotating tip vortex interaction

    NASA Technical Reports Server (NTRS)

    Majjigi, R. K.; Uenishi, K.; Gliebe, P. R.

    1989-01-01

    A tip vortex interaction model originally developed for compressors has been extended and adapted for use with counterrotating open rotors. Comparison of available acoustic data with predictions (made with and without the tip vortex model included) illustrate the importance of this interaction effect. This report documents the analytical modeling, a limited experimental verification, and certain key parametric studies pertaining to the tip vortex as a noise source mechanism for the unsteady loading noise of counterrotating properllers.

  18. Trace elements in hazardous mineral fibres.

    PubMed

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

    2016-09-01

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

  19. Trace elements in hazardous mineral fibres.

    PubMed

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

    2016-09-01

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

  20. Presynaptic Calcium Signalling in Cerebellar Mossy Fibres

    PubMed Central

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

    2009-01-01

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

  1. Monitoring of harmful gaseous emissions from land transport vehicles using a mid-infrared optical fibre sensor

    NASA Astrophysics Data System (ADS)

    Mulrooney, Jim; Clifford, John; Fitzpatrick, Colin; Lewis, Elfed

    2006-04-01

    This paper discusses the development of an optical fibre sensor suitable for the detection of gas emissions from motor vehicles based on mid-infrared spectroscopy. Initial measurements are presented for carbon dioxide emissions from a petrol engine using low-cost mid-infrared components, and a practical detection system, which could be fitted to a vehicle, is outlined.

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

    SciTech Connect

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

    2005-09-30

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

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

    NASA Astrophysics Data System (ADS)

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

    2009-11-01

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

  4. Advanced optical blade tip clearance measurement system

    NASA Technical Reports Server (NTRS)

    Ford, M. J.; Honeycutt, R. E.; Nordlund, R. E.; Robinson, W. W.

    1978-01-01

    An advanced electro-optical system was developed to measure single blade tip clearances and average blade tip clearances between a rotor and its gas path seal in an operating gas turbine engine. This system is applicable to fan, compressor, and turbine blade tip clearance measurement requirements, and the system probe is particularly suitable for operation in the extreme turbine environment. A study of optical properties of blade tips was conducted to establish measurement system application limitations. A series of laboratory tests was conducted to determine the measurement system's operational performance characteristics and to demonstrate system capability under simulated operating gas turbine environmental conditions. Operational and environmental performance test data are presented.

  5. Is there a magnitude effect in tipping?

    PubMed

    Green, Leonard; Myerson, Joel; Schneider, Rachel

    2003-06-01

    The present study examined nearly 1,000 tips recorded for two taxicabs, two hair salons, and two restaurants. In each of the six cases, amount of tip increased linearly as a function of the amount of the bill. Contrary to standard microeconomic theory, there was a magnitude effect in that as the amount of the bill increased, the percent tip tended to decrease. The present results extend the findings of Chapman and Winquist (1998), obtained using hypothetical scenarios, to real-world tipping behavior. Chapman and Winquist argued that a magnitude effect in tipping reflects the shape of the utility function for money. We suggest, however, that the magnitude effect may be the mathematical consequence of replotting the fundamental relationship between tip and bill amounts in terms of percent tip, given that the observed linear relation between tip and bill amounts has a positive intercept. We suggest further that the positive intercept arises because a tip represents a judgment as to what constitutes a fair or equitable wage, and part of what constitutes a fair wage is independent of the amount of the bill, reflecting compensation for simply being there when needed. The present account implies that different explanations may be needed for magnitude effects observed in different domains.

  6. RANS computations of tip vortex cavitation

    NASA Astrophysics Data System (ADS)

    Decaix, Jean; Balarac, Guillaume; Dreyer, Matthieu; Farhat, Mohamed; Münch, Cécile

    2015-12-01

    The present study is related to the development of the tip vortex cavitation in Kaplan turbines. The investigation is carried out on a simplified test case consisting of a NACA0009 blade with a gap between the blade tip and the side wall. Computations with and without cavitation are performed using a R ANS modelling and a transport equation for the liquid volume fraction. Compared with experimental data, the R ANS computations turn out to be able to capture accurately the development of the tip vortex. The simulations have also highlighted the influence of cavitation on the tip vortex trajectory.

  7. Turbine blade tip with offset squealer

    DOEpatents

    Bunker, Ronald Scott

    2001-01-01

    An industrial turbine assembly comprises a plurality of rotating blade portions in a spaced relation with a stationary shroud. The rotating blade includes a root section, an airfoil having a pressure sidewall and a suction sidewall defining an outer periphery and a tip portion having a tip cap. An offset squealer is disposed on the tip cap. The offset squealer is positioned inward from the outer periphery of the rotating blade. The offset squealer increases the flow resistance and reduces the flow of hot gas flow leakage for a given pressure differential across the blade tip portion so as to improve overall turbine efficiency.

  8. Tip-enhanced THz Raman spectroscopy for local temperature determination at the nanoscale.

    PubMed

    Balois, Maria Vanessa; Hayazawa, Norihiko; Catalan, Francesca Celine; Kawata, Satoshi; Yano, Taka-Aki; Hayashi, Tomohiro

    2015-11-01

    Local temperature of a nanoscale volume is precisely determined by tip-enhanced terahertz Raman spectroscopy in the low temperature range of several tens of degrees. Heat generated by the tip-enhanced electric field is directly transferred to single-walled carbon nanotubes by heat conduction and radiation at the nanoscale. This heating modulates the intensity ratio of anti-Stokes/Stokes Raman scattering of the radial breathing mode of the carbon nanotube based on the Boltzmann distribution at elevated temperatures. Owing to the low-energy feature of the radial breathing mode, the local temperature of the probing volume has been successfully extracted with high sensitivity. The dependence of the temperature rise underneath the tip apex on the incident power coincides with the analytical results calculated by finite element method based on the tip enhancement effect and the consequent steady-state temperature via Joule heat generation. The results show that the local temperature at the nanoscale can be controlled in the low temperature range simply by the incident laser power while exhibiting a sufficiently high tip enhancement effect as an analytical tool for thermally sensitive materials (e.g., proteins, DNA). Graphical Abstract Tip-enhanced THz Raman spectroscopy detects the low frequency Raman mode both in Stokes and anti-Stokes shifts, which precisely reflects the local temperature of the sample volume. PMID:26164304

  9. Tip-enhanced THz Raman spectroscopy for local temperature determination at the nanoscale.

    PubMed

    Balois, Maria Vanessa; Hayazawa, Norihiko; Catalan, Francesca Celine; Kawata, Satoshi; Yano, Taka-Aki; Hayashi, Tomohiro

    2015-11-01

    Local temperature of a nanoscale volume is precisely determined by tip-enhanced terahertz Raman spectroscopy in the low temperature range of several tens of degrees. Heat generated by the tip-enhanced electric field is directly transferred to single-walled carbon nanotubes by heat conduction and radiation at the nanoscale. This heating modulates the intensity ratio of anti-Stokes/Stokes Raman scattering of the radial breathing mode of the carbon nanotube based on the Boltzmann distribution at elevated temperatures. Owing to the low-energy feature of the radial breathing mode, the local temperature of the probing volume has been successfully extracted with high sensitivity. The dependence of the temperature rise underneath the tip apex on the incident power coincides with the analytical results calculated by finite element method based on the tip enhancement effect and the consequent steady-state temperature via Joule heat generation. The results show that the local temperature at the nanoscale can be controlled in the low temperature range simply by the incident laser power while exhibiting a sufficiently high tip enhancement effect as an analytical tool for thermally sensitive materials (e.g., proteins, DNA). Graphical Abstract Tip-enhanced THz Raman spectroscopy detects the low frequency Raman mode both in Stokes and anti-Stokes shifts, which precisely reflects the local temperature of the sample volume.

  10. Nanostar probes for tip-enhanced spectroscopy

    NASA Astrophysics Data System (ADS)

    Kim, Woong; Kim, Nara; Park, Joon Won; Kim, Zee Hwan

    2015-12-01

    To overcome the current limit of tip-enhanced spectroscopy that is based on metallic nano-probes, we developed a new scanning probe with a metallic nanostar, a nanoparticle with sharp spikes. A Au nanoparticle of 5 nm was first attached to the end of a tip through DNA-DNA hybridization and mechanical pick-up. The nanoparticle was converted to a nanostar with a core diameter of ~70 nm and spike lengths between 50 nm and 80 nm through the reduction of Au3+ with ascorbic acid in the presence of Ag+. Fabrication yields of such tips exceeded 60%, and more than 80% of such tips showed a mechanical durability sufficient for use in scanning microscopy. Effectiveness of the new probes for tip-enhanced Raman scattering (TERS) and tip-enhanced fluorescence (TEF) was confirmed. The probes exhibited the necessary enhancement for TEF, and the tip-on and tip-off ratios varied between 5 and 100. This large tip-to-tip variability may arise from the uncontrolled orientation of the apexes of the spike with respect to the sample surface, which calls for further fabrication improvement. The result overall supports a new fabrication approach for the probe that is effective for tip-enhanced spectroscopy.To overcome the current limit of tip-enhanced spectroscopy that is based on metallic nano-probes, we developed a new scanning probe with a metallic nanostar, a nanoparticle with sharp spikes. A Au nanoparticle of 5 nm was first attached to the end of a tip through DNA-DNA hybridization and mechanical pick-up. The nanoparticle was converted to a nanostar with a core diameter of ~70 nm and spike lengths between 50 nm and 80 nm through the reduction of Au3+ with ascorbic acid in the presence of Ag+. Fabrication yields of such tips exceeded 60%, and more than 80% of such tips showed a mechanical durability sufficient for use in scanning microscopy. Effectiveness of the new probes for tip-enhanced Raman scattering (TERS) and tip-enhanced fluorescence (TEF) was confirmed. The probes exhibited

  11. A Pr 3+-doped ZBLAN fibre upconversion laser pumped by an Yb 3+-doped silica fibre laser

    NASA Astrophysics Data System (ADS)

    Pask, H. M.; Tropper, A. C.; Hanna, D. C.

    1997-02-01

    An Yb 3+-doped silica fibre laser pumped at 840 nm has been used to provide the two pump wavelengths, 840 nm and 1020 nm, required for pumping a Pr 3+-doped ZBLAN fibre upconversion laser. The performance of the upconversion laser at 491, 520 and 635 nm is presented, with measurements of fibre loss at 635 nm and 520 nm which indicate that fibre losses are an important factor limiting the performance of the upconversion laser.

  12. Texas Intense Positron Source (TIPS)

    NASA Astrophysics Data System (ADS)

    O'Kelly, D.

    2003-03-01

    The Texas Intense Positron Source (TIPS) is a state of the art variable energy positron beam under construction at the Nuclear Engineering Teaching Laboratory (NETL). Projected intensities on the order of the order of 10^7 e+/second using ^64Cu as the positron source are expected. Owing to is short half-life (t1/2 12.8 hrs), plans are to produce the ^64Cu isotope on-site using beam port 1 of NETL TRIGA Mark II reactor. Following tungsten moderation, the positrons will be electrostatically focused and accelerated from few 10's of eV up to 30 keV. This intensity and energy range should allow routine performance of several analytical techniques of interest to surface scientists (PALS, PADB and perhaps PAES and LEPD.) The TIPS project is being developed in parallel phases. Phase I of the project entails construction of the vacuum system, source chamber, main beam line, electrostatic/magnetic focusing and transport system as well as moderator design. Initial construction, testing and characterization of moderator and beam transport elements are underway and will use a commercially available 10 mCi ^22Na radioisotope as a source of positrons. Phase II of the project is concerned primarily with the Cu source geometry and thermal properties as well as production and physical handling of the radioisotope. Additional instrument optimizing based upon experience gained during Phase I will be incorporated in the final design. Current progress of both phases will be presented along with motivations and future directions.

  13. Smart helicopter rotor with active blade tips

    NASA Astrophysics Data System (ADS)

    Bernhard, Andreas Paul Friedrich

    2000-10-01

    The smart active blade tip (SABT) rotor is an on-blade rotor vibration reduction system, incorporating active blade tips that can be independently pitched with respect to the main blade. The active blade tip rotor development included an experimental test program culminating in a Mach scale hover test, and a parallel development of a coupled, elastic actuator and rotor blade analysis for preliminary design studies and hover performance prediction. The experimental testing focussed on a small scale rotor on a bearingless Bell-412 hub. The fabricated Mach-scale active-tip rotor has a diameter of 1.524 m, a blade chord of 76.2 mm and incorporated a 10% span active tip. The nominal operating speed is 2000 rpm, giving a tip Mach number of 0.47. The blade tips are driven by a novel piezo-induced bending-torsion coupled actuator beam, located spanwise in the hollow mid-cell of the main rotor blade. In hover at 2000 rpm, at 2 deg collective, and for an actuation of 125 Vrms, the measured blade tip deflection at the first four rotor harmonics is between +/-1.7 and +/-2.8 deg, increasing to +/-5.3 deg at 5/rev with resonant amplification. The corresponding oscillatory amplitude of the rotor thrust coefficient is between 0.7 · 10-3 and 1.3 · 10-1 at the first four rotor harmonics, increasing to 2.1 · 10-3 at 5/rev. In general, the experimental blade tip frequency response and corresponding rotor thrust response are well captured by the analysis. The flexbeam root flap bending moment is predicted in trend, but is significantly over-estimated. The blade tips did not deflect as expected at high collective settings, because of the blade tip shaft locking up in the bearing. This is caused by the high flap bending moment on the blade tip shaft. Redesign of the blade tip shaft assembly and bearing support is identified as the primary design improvement for future research. The active blade tip rotor was also used as a testbed for the evaluation of an adaptive neural-network based

  14. Tunable diode and fibre laser spectroscopy in the near-IR for measurement of gas parameters

    NASA Astrophysics Data System (ADS)

    Stewart, George; Johnstone, Walter; Arsad, Norhana; Duffin, Kevin

    2008-04-01

    There has been much research performed in recent years on tunable diode laser spectroscopy for detection of gases such as methane, carbon dioxide, acetylene, etc., which possess near-IR absorption lines. To attain adequate sensitivity with weak near-IR lines, wavelength modulation spectroscopy with phase-sensitive detection is normally employed. However injection current modulation of diode lasers produces both wavelength and amplitude modulation, with a phase shift dependent on the modulation frequency. This results in residual amplitude modulation on the output and in distortion of the harmonic signals derived from the absorption line. These are important issues for calibration and where it is desired to accurately recover the line-shape function in order to make simultaneous measurements of gas concentration, pressure or temperature in industrial applications. Here we discuss how calibration-free measurements may be obtained with diode lasers and explore the implications for fibre laser based systems for spectroscopy which conventionally employ thermal or piezoelectric tuning of the wavelength. In particular, we consider modulation techniques which may be applied to ring fibre lasers which use un-pumped erbium fibre as a saturable absorber to prevent mode-hopping or to DFB fibre lasers which use a short cavity with a Bragg grating to ensure single mode operation.

  15. Fibre Break Failure Processes in Unidirectional Composites. Part 3: Unidirectional Plies Included in Laminates

    NASA Astrophysics Data System (ADS)

    Thionnet, A.; Chou, H. Y.; Bunsell, A.

    2015-04-01

    The purpose of these three papers is not to just revisit the modelling of unidirectional composites. It is to provide a robust framework based on physical processes that can be used to optimise the design and long term reliability of internally pressurised filament wound structures. The results given in paper Parts 1 and 2 concerning the behaviour of unidirectional composites, such as carbon fibre reinforced epoxy resin, are, here, extended to the behaviour of cross-plied composites consisting of unidirectional plies orientated at different angles with respect to the loading direction. In these laminates the plies orientated parallel to the loading direction (at 0∘) control the ultimate failure of the composite. This paper shows that the development of fibre breaks in analogous to that seen in the studies described in Part 1 and 2. Clustering of fibre breaks, shown by the development of 32-plets, preceedes failure just before specimen loaded monotonically break but develop in a more stable manner when subjected to steady high level loads. The effect of separating the 0∘ plies into thinner layers impedes the development of fibre breaks clusters and increases ultimate lifetimes.

  16. Macroscopic CNT fibres inducing non-epitaxial nucleation and orientation of semicrystalline polymers

    PubMed Central

    Yue, Hangbo; Monreal-Bernal, Alfonso; Fernández-Blázquez, Juan P.; Llorca, Javier; Vilatela, Juan J.

    2015-01-01

    In the presence of macroscopic fibres of carbon nanotubes (CNT), various semicrystalline polymers are shown to present accelerated crystallisation through the formation of a transcrystalline (TC) layer perpendicular to the fibre axis. From differential scanning calorimetry, polarized optical microscopy and X-ray diffraction we establish this to be due to much faster nucleation rates at the fibre surface. The formation of a TC layers is demonstrated for polyvinyldene fluoride, isotactic polypropylene and poly(lactic acid) in spite of the large differences in their chemistry and structure unit cells, suggesting that epitaxy in terms of lattice type or size matching is not a prerequisite. For the three polymers as well as poly(ether ether ketone), the TC layer is identically oriented with the chain axis in the lamella parallel to the CNTs, as observed by wide and small angle X-ray scattering. These results point to polymer chain orientation at the point of adsorption and the formation of a mesomorphic layer as possible steps in the fast nucleation of oriented lamella, with wetting of the CNT fibre surface by the molten semi-crystalline polymer a key condition for heterogeneous nucleation to take place. PMID:26578104

  17. Macroscopic CNT fibres inducing non-epitaxial nucleation and orientation of semicrystalline polymers.

    PubMed

    Yue, Hangbo; Monreal-Bernal, Alfonso; Fernández-Blázquez, Juan P; Llorca, Javier; Vilatela, Juan J

    2015-01-01

    In the presence of macroscopic fibres of carbon nanotubes (CNT), various semicrystalline polymers are shown to present accelerated crystallisation through the formation of a transcrystalline (TC) layer perpendicular to the fibre axis. From differential scanning calorimetry, polarized optical microscopy and X-ray diffraction we establish this to be due to much faster nucleation rates at the fibre surface. The formation of a TC layers is demonstrated for polyvinyldene fluoride, isotactic polypropylene and poly(lactic acid) in spite of the large differences in their chemistry and structure unit cells, suggesting that epitaxy in terms of lattice type or size matching is not a prerequisite. For the three polymers as well as poly(ether ether ketone), the TC layer is identically oriented with the chain axis in the lamella parallel to the CNTs, as observed by wide and small angle X-ray scattering. These results point to polymer chain orientation at the point of adsorption and the formation of a mesomorphic layer as possible steps in the fast nucleation of oriented lamella, with wetting of the CNT fibre surface by the molten semi-crystalline polymer a key condition for heterogeneous nucleation to take place. PMID:26578104

  18. FASEP ultra-automated analysis of fibre length distribution in glass-fibre-reinforced products

    NASA Astrophysics Data System (ADS)

    Hartwich, Mark R.; Höhn, Norbert; Mayr, Helga; Sandau, Konrad; Stengler, Ralph

    2009-06-01

    Reinforced plastic materials are widely used in high sophisticated applications. The length distribution of the fibres influences the mechanical properties of the final product. A method for automatic determination of this length distribution was developed. After separating the fibres out of the composite material without any damage, and preparing them for microscopical analysis, a mosaic of microscope pictures is taken. After image processing and analysis with mathematical methods, a complete statistic of the fibre length distribution could be determined. A correlation between fibre length distribution and mechanical properties, measured e.g. with material test methods, like tensile and impact tests, was found. This is a method to optimize the process and selection of material for the plastic parts. In result this enhances customer satisfaction and, maybe much more important, reduces costs for the manufacturer.

  19. Design of Tip Loss Profile on Support Rod for a Helix TWT

    NASA Astrophysics Data System (ADS)

    Alaria, Mukesh Kumar; Sinha, A. K.; Srivastava, V.

    2009-07-01

    This paper describes the design of tip loss profile on support rod for a high gain, high efficiency helix TWT. The tip loss profile at sever ends for the input and the output section of the helix slow wave structure has been designed for return loss at severs ends better than -20 dB. The experimental results have been carried out in the input and the output section of the helix assemblies for the high gain helix TWT to find the return loss in the region of carbon coated tip loss on the support rods. The experimental result has been compared with the simulated performance for the return loss at the sever ends. The design of tip loss profile on the support rod for helix TWT has been carried out in real situation using Ansoft HFSS. A good agreement has been found in the simulated and experimental results.

  20. Elemental Analysis of Glass Optical Fibres with High Spatial Resolution.

    NASA Astrophysics Data System (ADS)

    Pugh, Andrew

    Available from UMI in association with The British Library. The properties of glass optical fibres are very strongly dependent on the elemental concentration profiles of the fibre cores. Core dopants such as germanium define the core refractive index, which in turn defines the manner in which the light is transmitted through the fibre. Erbium in fibre cores can facilitate the operation of fibre lasers and aluminium in turn can control the erbium distribution. The aim of the project described in this thesis was to measure the elemental concentration profiles in a variety of fibre cores using X-ray microanalysis in an electron microscope. Conventional X-ray microanalysis of bulk samples has an analytical resolution in the order of a micron. With monomode optical fibre cores having cores typically three microns in diameter the resolution of the conventional technique is plainly inadequate. An experimental technique has been developed for the preparation of thin cross-sectional samples of glass optical fibres. Application of this technique has facilitated the preparation and analysis of thin film specimens with an average thickness of 400 microns. This approach has allowed analysis to be performed with an effective spatial resolution of 100-300 nm. The technique has been applied to the determination of germanium concentration in Raman fibres, to the investigation of erbium confinement in erbium doped fibres and to the investigation of inter-ionic diffusion in semiconductor doped fibres. It has been shown that the germanium, and hence refractive index, profile of germanium doped fibres is not changed by the process of fibre drawing. Evidence has been gathered supporting the theory of erbium confinement by aluminium and an important degree of elemental diffusion has been shown to take place during the drawing of semiconductor doped fibres. In addition an experimental technique has been developed for the preparation of thin cross-sectional samples of glass optical fibres.

  1. Lateral Tip Control Effects in CD-AFM Metrology: The Large Tip Limit

    PubMed Central

    Dixson, Ronald G.; Orji, Ndubuisi G.; Goldband, Ryan S.

    2016-01-01

    Sidewall sensing in critical dimension atomic force microscopes (CD-AFMs) usually involves continuous lateral dithering of the tip or the use of a control algorithm and fast response piezo actuator to position the tip in a manner that resembles touch-triggering of coordinate measuring machine (CMM) probes. All methods of tip position control, however, induce an effective tip width that may deviate from the actual geometrical tip width. Understanding the influence and dependence of the effective tip width on the dither settings and lateral stiffness of the tip can improve the measurement accuracy and uncertainty estimation for CD-AFM measurements. Since CD-AFM typically uses tips that range from 15 nm to 850 nm in geometrical width, the behavior of effective tip width throughout this range should be understood. The National Institute of Standards and Technology (NIST) has been investigating the dependence of effective tip width on the dither settings and lateral stiffness of the tip, as well as the possibility of material effects due to sample composition. For tip widths of 130 nm and lower, which also have lower lateral stiffness, the response of the effective tip width to lateral dither is greater than for larger tips. However, we have concluded that these effects will not generally result in a residual bias, provided that the tip calibration and sample measurement are performed under the same conditions. To validate that our prior conclusions about the dependence of effective tip width on lateral stiffness are valid for large CD-tips, we recently performed experiments using a very large non-CD tip with an etched plateau of approximately 2 μm width. The effective lateral stiffness of these tips is at least 20 times greater than typical CD-AFM tips, and these results supported our prior conclusions about the expected behavior for larger tips. The bottom-line importance of these latest observations is that we can now reasonably conclude that a dither slope of 3 nm

  2. Photoacoustic endoscopy probe using a coherent fibre-optic bundle and Fabry-Pérot ultrasound sensor (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Ansari, Rehman; Beard, Paul C.; Zhang, Edward Z.; Desjardins, Adrien E.

    2016-03-01

    There is considerable interest in the development of photoacoustic endoscopy (PAE) probes for the clinical assessment of pathologies in the gastrointestinal (GI) tract, guiding minimally invasive laparoscopic surgeries and applications in foetal medicine. However, most previous PAE probes integrate mechanical scanners and piezoelectric transducers at the distal end which can be technically complex, expensive and pose challenges in achieving the necessary level of miniaturisation. We present two novel all-optical forward-viewing endoscopic probes operating in widefield tomography mode that have the potential to overcome these limitations. In one configuration, the probe comprises a transparent 40 MHz Fabry-Pérot ultrasound sensor deposited at the tip of a rigid, 3 mm diameter coherent fibre-optic bundle. In this way, the distal end of coherent fibre bundle acts as a 2D array of wideband ultrasound detectors. In another configuration, an optical relay is used between the distal end face of flexible fibre bundle and the Fabry-Pérot sensor to enlarge the lateral field of view to 6 mm x 6 mm. In both configurations, the pulsed excitation laser beam is full-field coupled into the fibre bundle at the proximal end for uniform backward-mode illumination of the tissue at the probe tip. In order to record the photoacoustic waves arriving at the probe tip, the proximal end of the fibre bundle is optically scanned in 2D with a CW wavelength-tunable interrogation laser beam thereby interrogating different spatial points on the sensor. A time-reversal image reconstruction algorithm was used to reconstruct a 3D image from the detected signals. The 3D field of view of the flexible PAE probe is 6 mm x 6 mm x 6 mm and the axial and lateral spatial resolution is 30 µm and 90 µm, respectively. 3D imaging capability is demonstrated using tissue phantoms, ex vivo tissues and in vivo. To the best of our knowledge, this is the first forward-viewing implementation of a photoacoustic

  3. Two-frequency fibre Raman laser

    SciTech Connect

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

    2004-03-31

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

  4. Applications of magnetically active fibre reinforced composites

    NASA Astrophysics Data System (ADS)

    Etches, Julie; Bond, Ian; Mellor, Philip

    2005-05-01

    As the application of fibre reinforced polymer composites (FRP) becomes more widespread there is a desire to add functionality beyond that of simple mechanical properties in order to facilitate the development of 'smart' materials. For example, the functionality being discussed in this paper is the imparting of significant magnetic properties to a FRP. This can take the form of soft magnetic performance for use in electrical machines or hard magnetic performance for novel forms of sensing or power generation. It has been demonstrated that by using hollow glass fibres as a reinforcement, magnetic material can be introduced into these fibres without significant effects on the structural behaviour of the FRP. The current studies have included the assessment of such a magnetic FRP in a variety of applications. The addition of hard magnetic materials, e.g. magnetite and barium ferrite, has been achieved through the use of nanopowders and the resulting FRP has been assessed for morphing structures applications. The magnitude of magnetic performance that can be currently achieved is controlled by the availability of suitable magnetic materials in fine powder form and the volume of magnetic material which can be incorporated within the fibres.

  5. The structure of boron in boron fibres

    NASA Technical Reports Server (NTRS)

    Bhardwaj, J.; Krawitz, A. D.

    1983-01-01

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

  6. Mersilene tip implants in rhinoplasty: a review of 98 cases.

    PubMed

    Fanous, N

    1991-04-01

    Reshaping the nasal tip is the most difficult part of a rhinoplasty, particularly in certain types of nasal tip deformities, such as the recessed tip, the thick-skin tip, the boxy tip, the asymmetrical tip, the thin-skin tip, the bifid tip, the turned-up tip, and the turned-down tip. A new approach is introduced regarding the use of Mersilene tip implants. Guidelines for preoperative evaluation and surgical technique are outlined. The so-called "PEPSI" rule (pocket, experience, positioning, shape and size, and incision) is emphasized. The advantages and disadvantages of the Mersilene tip implant are discussed. The Mersilene implant was used in the tip region in a total of 98 patients, and the results are satisfactory.

  7. Ten Fire Safety Tips for Schools.

    ERIC Educational Resources Information Center

    Lake, James D.

    1999-01-01

    Provides 10 basic tips, compiled from the National Fire Protection Association's Life Safety Code 101, to ensure that educational facilities are fire safe. Tips include use of frequent and unexpected fire drills, limiting wall space of student artwork and teaching materials, being alert to preventing arson, planning speedy and safe emergency…

  8. Medical Errors: Tips to Help Prevent Them

    MedlinePlus

    ... to Web version Medical Errors: Tips to Help Prevent Them Medical Errors: Tips to Help Prevent Them Medical errors are one of the nation's ... single most important way you can help to prevent errors is to be an active member of ...

  9. The Tipping Point in School Culture

    ERIC Educational Resources Information Center

    Nelsen, Jeff; Hill, Bob

    2009-01-01

    Once changes or innovations reach the tipping point, they spread throughout an organization and become entrenched as part of the culture, becoming "just the way we do things around here." These authors see the tipping point at play with systemic improvement in two urban school districts with which they have worked. Here, they describe the lessons…

  10. Managing Tips for Teachers of the Gifted.

    ERIC Educational Resources Information Center

    Hays, Betsy Bauer; Conley, Jane Bauer

    1993-01-01

    Ten tips are provided to help teachers of gifted students cope with the unique stressors that they face. Tips include making parents allies, putting grades in perspective, and setting realistic goals. Activities are presented for use as introductory "ice-breakers" or concluding activities for workshops for teachers and parents of gifted students.…

  11. News: Tripping over tipping points/elements

    EPA Science Inventory

    The term “tipping point” has been used to identify a critical threshold susceptible to a tiny perturbation that can qualitatively alter the state or development of a system. “Tipping element” has been introduced to describe large-scale components of the Earth system that may pass...

  12. 'Oxide-free' tip for scanning tunneling microscopy

    NASA Technical Reports Server (NTRS)

    Colton, R. J.; Baker, S. M.; Baldeschwieler, J. D.; Kaiser, W. J.

    1987-01-01

    A new tip for scanning tunneling microscopy and a tip repair procedure that allows one to reproducibly obtain atomic images of highly oriented pyrolytic graphite with previously inoperable tips are reported. The tips are shown to be relatively oxide-free and highly resistant to oxidation. The tips are fabricated with graphite by two distinct methods.

  13. Tip cap for a turbine rotor blade

    DOEpatents

    Kimmel, Keith D

    2014-03-25

    A turbine rotor blade with a spar and shell construction, and a tip cap that includes a row of lugs extending from a bottom side that form dovetail grooves that engage with similar shaped lugs and grooves on a tip end of the spar to secure the tip cap to the spar against radial displacement. The lug on the trailing edge end of the tip cap is aligned perpendicular to a chordwise line of the blade in the trailing edge region in order to minimize stress due to the lugs wanting to bend under high centrifugal loads. A two piece tip cap with lugs at different angles will reduce the bending stress even more.

  14. Molecular Mechanics of Tip-Link Cadherins

    NASA Astrophysics Data System (ADS)

    Sotomayor, Marcos; Weihofen, Wilhelm A.; Gaudet, Rachelle; Corey, David P.

    2011-11-01

    The hair-cell tip link, a fine filament directly conveying force to mechanosensitive transduction channels, is likely composed of two proteins, protocadherin-15 and cadherin-23, whose mutation causes deafness. However, their complete molecular structure, elasticity, and deafness-related structural defects remain largely unknown. We present crystal structures of extracellular (EC) tip-link cadherin repeats involved in hereditary deafness and tip link formation. In addition, we show that the deafness mutation D101G, in the linker region between the repeats EC1 and EC2 of cadherin-23, causes a slight bend between repeats and decreases Ca2+ affinity. Molecular dynamics simulations suggest that tip-link cadherin repeats are stiff and that either removing Ca2+ or mutating Ca2+-binding residues reduces rigidity and unfolding strength. The structures and simulations also suggest mechanisms underlying inherited deafness and how cadherin-23 may bind with protocadherin-15 to form the tip link.

  15. Surface Treated Natural Fibres as Filler in Biocomposites

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  16. Self-assembled fibre optoelectronics with discrete translational symmetry

    NASA Astrophysics Data System (ADS)

    Rein, Michael; Levy, Etgar; Gumennik, Alexander; Abouraddy, Ayman F.; Joannopoulos, John; Fink, Yoel

    2016-10-01

    Fibres with electronic and photonic properties are essential building blocks for functional fabrics with system level attributes. The scalability of thermal fibre drawing approach offers access to large device quantities, while constraining the devices to be translational symmetric. Lifting this symmetry to create discrete devices in fibres will increase their utility. Here, we draw, from a macroscopic preform, fibres that have three parallel internal non-contacting continuous domains; a semiconducting glass between two conductors. We then heat the fibre and generate a capillary fluid instability, resulting in the selective transformation of the cylindrical semiconducting domain into discrete spheres while keeping the conductive domains unchanged. The cylindrical-to-spherical expansion bridges the continuous conducting domains to create ~104 self-assembled, electrically contacted and entirely packaged discrete spherical devices per metre of fibre. The photodetection and Mie resonance dependent response are measured by illuminating the fibre while connecting its ends to an electrical readout.

  17. Self-assembled fibre optoelectronics with discrete translational symmetry

    PubMed Central

    Rein, Michael; Levy, Etgar; Gumennik, Alexander; Abouraddy, Ayman F.; Joannopoulos, John; Fink, Yoel

    2016-01-01

    Fibres with electronic and photonic properties are essential building blocks for functional fabrics with system level attributes. The scalability of thermal fibre drawing approach offers access to large device quantities, while constraining the devices to be translational symmetric. Lifting this symmetry to create discrete devices in fibres will increase their utility. Here, we draw, from a macroscopic preform, fibres that have three parallel internal non-contacting continuous domains; a semiconducting glass between two conductors. We then heat the fibre and generate a capillary fluid instability, resulting in the selective transformation of the cylindrical semiconducting domain into discrete spheres while keeping the conductive domains unchanged. The cylindrical-to-spherical expansion bridges the continuous conducting domains to create ∼104 self-assembled, electrically contacted and entirely packaged discrete spherical devices per metre of fibre. The photodetection and Mie resonance dependent response are measured by illuminating the fibre while connecting its ends to an electrical readout. PMID:27698454

  18. Sensing properties of germanate and tellurite glass optical fibres

    NASA Astrophysics Data System (ADS)

    Li, Hongxia; Lousteau, Joris; Suo, Rui; Jiang, Xin; MacPherson, William N.; Bookey, Henry T.; Barton, James S.; Kar, Ajoy K.; Zhang, Lin; Jha, Animesh; Bennion, Ian

    2009-10-01

    Strain and thermal sensitivities of germanate and tellurite glass fibres were measured using a fibre Fabry-Perot (FFP) interferometer and fibre Bragg gratings (FBG). The strain phase sensitivity for germanate and tellurite fibre were 5900×103 rad/m and 5600×103 rad/m respectively at a central wavelength of 1540nm using FFP interferometer, which is consistent with the value of 1.22pm/μɛ obtained for a germanate fibre FBG. The Young's modulus for germanate and tellurite fibre were also measured to be 58GPa and 37GPa. The thermal responses of germanate fibre were examined as 24.71 and 16.80 pm/°C at 1540nm and 1033nm wavelength using the FBG.

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

    PubMed Central

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

    1973-01-01

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

  20. Transcaval TIPS in Patients with Failed Revision of Occluded Previous TIPS

    PubMed Central

    Kim, Yong Joo; Shin, Tae Beom; Park, Hyo Yong; Kim, Tae Hun; Kang, Duk Sik

    2001-01-01

    Objective To determine the feasibility of transcaval transjugular intrahepatic portosystemic shunt (TIPS) in patients with occluded previous TIPS. Materials and Methods Between February 1996 and December 2000 we performed five transcaval TIPS procedures in four patients with recurrent gastric cardiac variceal bleeding. All four had occluded TIPS, which was between the hepatic and portal vein. The interval between initial TIPS placement and revisional procedures with transcaval TIPS varied between three and 31 months; one patient underwent transcaval TIPS twice, with a 31-month interval. After revision of the occluded shunt failed, direct cavoportal puncture at the retrohepatic segment of the IVC was attempted. Results Transcaval TIPS placement was technically successful in all cases. In three, tractography revealed slight leakage of contrast materials into hepatic subcapsular or subdiaphragmatic pericaval space. There was no evidence of propagation of extravasated contrast materials through the retroperitoneal space or spillage into the peritoneal space. After the tract was dilated by a bare stent, no patient experienced trans-stent bleeding and no serious procedure-related complications occurred. After successful shunt creation, variceal bleeding ceased in all patients. Conclusion Transcaval TIPS placement is an effective and safe alternative treatment in patients with occluded previous TIPS and no hepatic veins suitable for new TIPS. PMID:11754327